Method for producing a columnar honeycomb structure filter and device for attaching particles for columnar honeycomb structure

Abstract

Method for producing a columnar honeycomb structure filter (100, 500), comprising: a step of producing a columnar honeycomb structure comprising: several first cells (108) extending from an inlet-side end face (104, 504) to an outlet-side end face (106, 506), each opening at the inlet-side end face (104, 504) and having a closed section (109) at the outlet-side end face (106, 506), and several second cells (110) extending from the inlet-side end face (104, 504) to the outlet-side end face (106, 506), each having a closed section (109) at the inlet-side end face (104, 504) and opening at the outlet-side end face (106, 506), the several first cells (108) and the several second cells (110) being alternately adjacent to each other with a porous partition (112) between them, and a step of attaching ceramic particles (412, 422, 432) to a surface of the first cells (108) by ejecting an aerosol containing the ceramic particles (412, 422, 432) in the direction of the inlet-side end face (104, 504) from a direction perpendicular to the inlet-side end face (104, 504), while a suction force is exerted on the outlet-side end face (106, 506) to draw the ejected aerosol away from the inlet-side end face (104, 504); wherein the emission of the aerosol is carried out using an aerosol generator (410, 420, 430, 511, 610) which has a drive gas flow path (417, 427, 437) for guiding a pressurized drive gas, a feed port (417i, 427i, 437i) provided on the drive gas flow path (417, 427, 437) which can draw the ceramic particles (412, 422, 432) from an outer circumferential side of the drive gas flow path (417, 427, 437) to an inner side of the drive gas flow path (417, 427, 437), and a nozzle (411, 421, 431, 511q) located at a tip of the drive gas flow path (417, 427, 437) is attached and can emit the aerosol, includes, where The aerosol (411, 421, 431, 511a) ejected from the nozzle flows through a chamber (513) provided between the nozzle (411, 421, 431, 511a) and the inlet-side end face (104, 504) and is drawn in by the inlet-side end face (104, 504). the chamber (513) has a surface (513a) opposite the inlet-side end face (104, 504), the opposite surface (513a) has an insertion port for the nozzle (411, 421, 431, 511a) and one or more openings (513c) for letting ambient gas into the chamber (513), and the chamber (513) has no openings for letting in ambient gas other than those on the opposite surface (513a).

Description

Field of invention

[0001] The present invention relates to a method for producing a columnar honeycomb filter. The present invention also relates to a device for attaching particles to a columnar honeycomb structure. Background of the invention

[0002] Fine particulate matter (hereinafter referred to as PM), such as soot, is contained in the exhaust gas emitted from internal combustion engines, such as diesel and gasoline engines. Soot is harmful to the human body, and its emission is regulated. Currently, to comply with emissions regulations, filters such as diesel particulate filters (DPF) and gasoline particulate filters (GPF) are widely used. These filters direct exhaust gas through permeable baffles with small pores, filtering out PM such as soot.

[0003] A columnar honeycomb structure filter of the wall flow type is known as a filter for collecting PM, comprising: several first cells extending vertically from an inlet-side end face to an outlet-side end face, opening on the inlet-side end face and having closed sections on the outlet-side end face, and several second cells arranged adjacent to the first cells with partitions inserted between them, extending vertically from the inlet-side end face to the outlet-side end face, having blocked sections on the inlet-side end face and opening on the outlet-side end face.

[0004] In recent years, stricter PM emission standards (PM number regulations) have been introduced with the tightening of exhaust emission regulations, requiring filters to have high PM collection performance (high PM collection efficiency). Therefore, it has been proposed to form a PM collection layer (hereinafter also referred to as a "porous film" or "collection layer") on the surface of the cells (Patent Documents 1 to 7). According to these patent documents, forming the porous film makes it possible to collect PM while simultaneously reducing pressure drop. The process for forming the porous film involves feeding particles smaller than the average diameter of the particles forming the partitions to the inlet-side face of the filter via a solid-gas two-phase flow. These particles are then deposited on the surface of the first cells and subsequently undergo heat treatment.Further relevant prior art is disclosed in the following documents: DE 10 2020 007 934 A1, DE 10 2018 127 957 A1, DE 10 2018 111 246 A1 and US 2011 / 0 229 634 A1. List of prior art patent document(s) [Patent Document 1] WO 2010 / 110010 A1 [Patent document 2] WO 2011 / 125768 A1 [Patent document 3] WO 2011 / 125769 A1 [Patent Document 4] JP 5863951 B2 [Patent Document 5] JP 2011-147931 A [Patent Document 6] JP ​​5863950 B2 [Patent Document 7] JP 5597148 B2 Summary of the invention

[0005] Forming a porous film on the surface of the cells is considered effective in improving the PM collection performance of the columnar honeycomb filter. However, according to the results of the present inventors' study, it was found that with conventional porous film formation techniques, the particles contained in the solid-gas two-phase flow fed to the inlet-side face of the filter are likely to aggregate. When the particles aggregate, it becomes difficult to attach them to the surface of the first cells with the desired particle diameter distribution, and the PM collection performance can be adversely affected by the porous film.Therefore, when the step of attaching the particles to the surface of the first cells is carried out, from the point of view of quality control it is desirable that the particles are fed to the inlet-side end surface with suppressed aggregation.

[0006] Accordingly, in one embodiment, it is an object of the present invention to provide a method for producing a columnar honeycomb filter, comprising a step of feeding particles with suppressed aggregation to the inlet-side end face of a columnar honeycomb structure and attaching the particles to the surface of the first cells. Furthermore, in another embodiment, it is an object of the present invention to provide a device for attaching particles to a columnar honeycomb structure, which is advantageous for carrying out a step of feeding particles with suppressed aggregation to the inlet-side end face of the columnar honeycomb structure and attaching the particles to the surface of the first cells.

[0007] As a result of careful studies aimed at solving the aforementioned problems, the inventors of the present invention have found that it is effective to suppress particle aggregation by emitting an aerosol containing ceramic particles towards the inlet-side end face of the columnar honeycomb structure using an aerosol generator with a predetermined configuration. The present invention was conceived based on the foregoing findings and is explained below by way of example.

[0008] [1] Method for producing a columnar honeycomb structure filter comprising: one step in creating a columnar honeycomb structure, which includes: several first cells extending from an inlet-side end face to an outlet-side end face, each opening at the inlet-side end face and having a closed section at the outlet-side end face, and several second cells extending from the inlet-side end face to the outlet-side end face, each having a closed section at the inlet-side end face and opening at the outlet-side end face, the several first cells and the several second cells being arranged alternately adjacent to each other with a porous partition between them, and a step of attaching ceramic particles to a surface of the first cells by ejecting an aerosol containing the ceramic particles in the direction of the inlet-side end face from a direction perpendicular to the inlet-side end face, while a suction force is exerted on the outlet-side end face to draw the ejected aerosol away from the inlet-side end face; wherein the ejection of the aerosol is carried out using an aerosol generator comprising a drive gas flow path for guiding a pressurized drive gas, a feed port provided along the drive gas flow path and capable of drawing the ceramic particles from an outer circumferential side of the drive gas flow path to an inner side of the drive gas flow path, and a nozzle located at a tip of the drive gas flow path and capable of ejecting the aerosol, wherein the aerosol ejected from the nozzle flows through a chamber provided between the nozzle and the inlet-side end face and is drawn from the inlet-side end face, the chamber having a surface opposite the inlet-side end face, the opposite surface having an insertion port for the nozzle and one or more openings for admitting ambient gas into the chamber,and the chamber has no openings for letting in ambient gas other than those on the opposite surface.

[0009] [2] Method according to [1], wherein the ceramic particles in the aerosol have a median diameter (D50) of 1.0 to 6.0 µm in a volume-based cumulative particle diameter distribution measured by a laser diffraction / laser scattering method.

[0010] [3] Manufacturing process according to [1] or [2], wherein, for the ceramic particles in the aerosol, in a volume-based particle diameter frequency distribution measured by the laser diffraction / laser scattering method, the ceramic particles of 10 µm or more constitute 20 vol.-% or less.

[0011] [4] Method according to [3], wherein the surface of the chamber facing the inlet-side end face has a concentric closure section centered on the insertion port and one or more openings are provided on an outer circumferential side of the closure section.

[0012] [5] Method according to any of points [1] to [4], wherein the aerosol generator further comprises: a cylinder for receiving the ceramic particles, a piston or a screw for expelling the ceramic particles contained in the cylinder from a cylinder outlet, and a loosening chamber comprising an inlet connected to the cylinder outlet, a rotating body for loosening the ceramic particles discharged from the cylinder outlet and an outlet connected to the supply port.

[0013] [6] Method according to any of points [1] to [4], wherein the aerosol generator further comprises: a flow path for drawing in and transporting the ceramic particles, which includes an outlet connected to the feed port, and a receiving unit for receiving the ceramic particles and for feeding the ceramic particles to the flow path for suction and transport; wherein the propulsion gas flow path includes a Venturi section in which the flow path is narrowed, and the supply port is provided on the downstream side of the narrowest point of the flow path in the Venturi section.

[0014] [7] Method according to any of points [1] to [4], wherein the aerosol generator further comprises: a flow path for drawing in and transporting the ceramic particles, which includes an outlet that is connected to the supply port, a belt conveyor for transporting the ceramic particles and a loosening chamber comprising an inlet for receiving the ceramic particles transported by the belt conveyor, a rotating body for loosening the received ceramic particles and an outlet connected to the flow path for suction and transport.

[0015] [8] Method according to one of points [1] to [7], wherein an endpoint of the step of attaching the ceramic particles to the surface of the first cells is determined based on a value of a differential pressure gauge installed to measure the pressure loss between the inlet-side end face and the outlet-side end face of the columnar honeycomb structure.

[0016] [9] Method according to one of points [1] to [7], wherein in the step of applying the ceramic particles to the surface of the first cells the average flow velocity of the aerosol flowing within the columnar honeycomb structure is 5 m / s or more.

[0017]

[10] Method according to one of points [1] to [9], wherein a major component of the ceramic particles is silicon carbide, aluminium oxide, silicon dioxide, cordierite or mullite.

[0018]

[11] Device for attaching particles for a columnar honeycomb structure, comprising: a holder for holding the columnar honeycomb structure comprising: several first cells extending from an inlet-side end face to an outlet-side end face, each opening at the inlet-side end face and having a closed section at the outlet-side end face, and several second cells extending from the inlet-side end face to the outlet-side end face, each having a closed section at the inlet-side end face and opening at the outlet-side end face, the several first cells and the several second cells being arranged alternately adjacent to each other with a porous partition between them, a blower for applying a suction force to the outlet-side end face of the columnar honeycomb structure, and an aerosol generator for emitting an aerosol containing ceramic particles in the direction of the inlet-side end face from a direction perpendicular to the inlet-side end face and attaching the ceramic particles to a surface of the first cells; wherein the aerosol generator comprises: a drive gas flow path for guiding a pressurized drive gas, a supply port which is located on the path the drive gas flow path is provided and can draw the ceramic particles from an outer circumferential side of the drive gas flow path towards an inner side of the drive gas flow path, and a nozzle is attached to a tip of the drive gas flow path and can expel the aerosol, the device further comprising a chamber provided between the nozzle and the inlet-side end face to guide the aerosol through its interior, the chamber having a surface opposite the inlet-side end face, the opposite surface having an insertion port for the nozzle and one or more openings for admitting ambient gas into the chamber, and the chamber having no other openings for admitting ambient gas than those on the opposite surface.

[0019]

[12] Device for attaching particles for a columnar honeycomb structure according to

[11] , wherein the opposite surface has a concentric closure section centered on the insertion port and one or more openings are provided on an outer circumferential side of the closure section.

[0020]

[13] Device for attaching particles for a columnar honeycomb structure according to any one of points

[11] to

[12] , the aerosol generator further comprising: a cylinder for receiving the ceramic particles, a piston or a screw for expelling the ceramic particles contained in the cylinder from a cylinder outlet, and a loosening chamber comprising an inlet connected to the cylinder outlet, a rotating body for loosening the ceramic particles discharged from the cylinder outlet and an outlet connected to the supply port.

[0021]

[14] Device for attaching particles for a columnar honeycomb structure according to any one of points

[11] to

[12] , wherein the aerosol generator further comprises: a flow path for drawing in and transporting the ceramic particles, which has an outlet that is connected to the supply port, and a receiving unit for receiving the ceramic particles and for feeding the ceramic particles to the flow path for suction and transport; wherein the propulsion gas flow path has a Venturi section along its route in which the flow path is narrowed, and the supply port is provided on the downstream side of the narrowest point of the flow path in the Venturi section.

[0022]

[15] Device for attaching particles for a columnar honeycomb structure according to any of points

[11] to

[12] , wherein the aerosol generator further comprises: a flow path for drawing in and transporting the ceramic particles, which includes an outlet that is connected to the supply port, a belt conveyor for transporting the ceramic particles and a loosening chamber which has an inlet for receiving the ceramic particles transported by the belt conveyor, a rotating body for loosening the received ceramic particles and an outlet connected to the flow path for suction and transport.

[0023] According to the method for manufacturing a columnar honeycomb filter and the device for attaching particles in an embodiment of the present invention, particles with suppressed aggregation can be introduced onto the inlet-side end face of the columnar honeycomb structure. Therefore, it is possible to attach particles with a targeted particle diameter distribution to the surface of the first cells. Furthermore, it is expected that the quality stability of the porous film formed by the heat treatment after the particle attachment step will be improved. Brief description of the drawings Fig. Figure 1 is a perspective view that schematically shows an example of a columnar honeycomb structure filter. Fig.Figure 2 is a schematic cross-sectional view showing an example of a columnar honeycomb structure filter from a cross-section parallel to the direction in which the cells extend. Fig. Figure 3 is a schematic, partially enlarged view of a columnar honeycomb structure filter as viewed from a cross-section perpendicular to the direction in which the cells extend. Fig. Figure 4A is a representation that schematically shows a first embodiment of an aerosol generator suitable for ejecting ceramic particles, wherein aggregation is suppressed. Fig. Figure 4B is a representation schematically showing a second embodiment of an aerosol generator suitable for ejecting ceramic particles, wherein aggregation is suppressed. Fig.Figure 4C is a representation that schematically shows a third embodiment of an aerosol generator suitable for ejecting ceramic particles, wherein aggregation is suppressed. Fig. 4D is a representation that schematically shows an aerosol generator according to a comparative example. Fig. Figure 5A is a schematic representation to illustrate a device configuration of a first embodiment of the device for attaching particles according to an embodiment of the present invention. Fig. Figure 5B is a schematic representation to illustrate a device configuration of a second embodiment of the device for attaching particles according to an embodiment of the present invention. Fig.Figure 5C is a schematic representation to illustrate a device configuration of a third embodiment of the device for attaching particles according to an embodiment of the present invention. Detailed description of the invention

[0024] The following sections describe in detail embodiments of the present invention with reference to the drawings. It is understood that the present invention is not limited to the following embodiments and that any modifications, improvements, or the like may be appropriately added to the design based on the common knowledge of those skilled in the art, without departing from the concept of the present invention. <1. Columnar honeycomb structure filter>

[0025] A columnar honeycomb filter according to an embodiment of the present invention is described. A columnar honeycomb filter can be used as a DPF (diesel particulate filter) or a GPF (gasoline particulate filter) that collects soot and is mounted on an exhaust pipe from a combustion device, typically an engine mounted on a vehicle. The columnar honeycomb filter according to the present invention can, for example, be installed in an exhaust pipe.

[0026] Fig. 1 and Fig.Figure 2 shows a schematic perspective view or a cross-sectional view of a columnar honeycomb structure filter (100).This columnar honeycomb filter (100) comprises an outer circumferential sidewall (102) and several first cells (108) provided on the inner circumferential side of the outer circumferential sidewall (102), wherein the several first cells (108) extend from an inlet-side end face (104) to an outlet-side end face (106), each opening at the inlet-side end face (104) and having a closed section (109) at the outlet-side end face (106), and several second cells (110) provided on the inner circumferential side of the outer circumferential sidewall (102), wherein the several second cells (110) extend from the inlet-side end face (104) to the outlet-side end face (106), each having a closed section (109) at the inlet-side end face (104) and opening at the outlet-side end face (106). (106) opens.Since in this columnar honeycomb structure (100) the first cells (108) and the second cells (110) are arranged alternately adjacent to each other with a porous partition (112) in between, the inlet-side end face (104) and the outlet-side end face (106) each have a honeycomb shape.

[0027] When exhaust gas containing particulate matter (PM) such as soot is fed to the inlet-side end face (104), located on the upstream side of the columnar honeycomb filter (100), the exhaust gas is introduced into the first cells (108) and travels downstream within them. Because the first cells (108) have blocked sections (109) on the outlet-side end face (106), located on the downstream side, the exhaust gas passes through the porous partitions (112) that separate the first cells (108) and the second cells (110) and flows into the second cells (110). Since particulate matter cannot pass through the partitions (112), it is collected and deposited in the first cells (108). After the particles are removed, the clean exhaust gas that flowed into the second cells (110) flows downstream into the second cells (110) and flows out of the outlet-side end face (106), which is located on the downstream side.

[0028] Fig. Figure 3 shows a schematic, partially enlarged view of the columnar honeycomb filter (100) in a cross-section perpendicular to the direction in which the cells (108, 110) extend. Porous films (114) are formed on the surface of each of the first cells (108) (equivalent to the surfaces of the partitions (112) separating the first cells (108)) of the columnar honeycomb filter (100).

[0029] In one embodiment, the porosity of the porous films (114) is higher than the porosity of the partitions (112). If the porosity of the porous films (114) is higher than the porosity of the partitions (112), the advantage is that an increase in pressure drop can be suppressed. In this case, the difference between the porosity of the porous films (114) and the porosity (%) of the partitions (112) is preferably 5% or more, and more preferably 10% or more. However, if the porosity difference is too large, the PM collection efficiency decreases, so the difference between the porosity (%) of the porous films (114) and the porosity (%) of the partitions (112) is preferably 30% or less, and more preferably 25% or less.

[0030] The lower limit of the porosity of the porous films is preferably 60% or more, and more preferably 65% ​​or more, with a view to suppressing an increase in pressure drop. Furthermore, the upper limit of the porosity of the porous film is preferably 85% or less, and more preferably 80% or less, with a view to suppressing a decrease in the collection efficiency for PM.

[0031] The lower limit of the porosity of the partition walls, with regard to suppressing the pressure drop of the exhaust gas, is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. Furthermore, the upper limit of the porosity of the partition wall, with regard to ensuring the strength of the columnar honeycomb filter, is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.

[0032] The porosity of the porous films and partitions is measured as follows. A scanning electron microscope (SEM) image (dimensions per field of view: 150 µm × 150 µm) of a cross-section of the porous films (or partitions) is photographed at a magnification of 1000x or higher, and image processing software is used to perform binarization of the empty and solid sections. Next, the area fraction occupied by the empty sections in the field of view is determined in five or more arbitrary fields of view, and the mean of these fractions is defined as the porosity (%) of the porous films (or partitions).

[0033] In one embodiment, the average pore diameter of the porous films is 1.0 to 6.0 µm. The partitions are also porous, but the average pore diameter of the partitions is typically larger than 6.0 µm to prevent excessive pressure drop. Therefore, by reducing the average pore diameter of the porous films formed on the surface of the partitions to 1.0 to 6.0 µm, it is possible to improve the PM collection efficiency while simultaneously suppressing an increase in pressure drop as the exhaust gas passes through the partitions. The average pore diameter of the porous films is preferably 2.0 to 5.0 µm, more preferably 3.0 to 4.0 µm.

[0034] The average pore diameter in the porous films and partitions is measured using the following procedure. A scanning electron microscope (SEM) image (dimensions per field of view: 150 µm × 150 µm) of a cross-section of the porous films (or partitions) is photographed at a magnification of 1000x or higher, and image processing software is used to perform binarization of the empty and solid sections. Within the SEM image, a circular equivalent diameter of each cavity forming the cavity sections is measured using image processing software and averaged to obtain the average pore diameter per field of view. The measurement of the average pore diameter is obtained from any five or more fields of view, and the average of these measurements is defined as the measured value of the average pore diameter.

[0035] The porous film can be made of ceramics. For example, the porous film can contain one or more ceramics selected from cordierite, silicon carbide (SiC), talc, mica, mullite, clay shards, aluminum titanate, aluminum oxide, silicon nitride, sialon, zirconium phosphate, zirconium dioxide, titanium dioxide, and silicon dioxide. The main component of the porous film is preferably silicon carbide, aluminum oxide, silicon dioxide, cordierite, or mullite. Among these, silicon carbide is preferred as the main component because the presence of the surface oxide film (Si₂O) allows the porous film to be tightly bonded and difficult to detach. The main component of the porous film refers to a component that constitutes 50% or more by weight of the porous film. SiC preferably makes up 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more of the porous film.The shape of the ceramic forming the porous film is not particularly limited, and examples include granular and fibrous forms.

[0036] Examples of the material forming the porous partitions and the outer circumferential sidewall of the columnar honeycomb filter according to the present embodiment include, but are not limited to, porous ceramics. Examples of ceramics include cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, indialite, sapphire, corundum, titanium dioxide, silicon nitride, and the like. The ceramic may be a single type or may be two or more types.

[0037] The columnar honeycomb filter can carry a PM combustion catalyst that supports PM combustion, such as soot; an oxidation catalyst (DOC); an SCR catalyst; an NSR catalyst for removing nitrogen oxides (NOx); and a three-way catalyst that can simultaneously remove hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Various catalysts can also be carried on the columnar honeycomb filter according to the present embodiment.

[0038] The shape of the end faces of the columnar honeycomb filter is not restricted and can, for example, be a round shape such as a circle, an ellipse, a racetrack shape, or an oval shape, or a polygon such as a triangle or a quadrilateral. The columnar honeycomb structure (100) of Fig. 1 has a circular end face and is cylindrical overall.

[0039] The height of the columnar honeycomb filter (the length from the inlet end face to the outlet end face) is not particularly limited and can be adjusted as needed, depending on the application and required performance. There is no particular restriction on the relationship between the height of the columnar honeycomb filter and the maximum diameter of each end face (referring to the maximum length of the diameters passing through the center of gravity of each end face of the columnar honeycomb filter). Therefore, the height of the columnar honeycomb filter can be longer than the maximum diameter of each end face, or the height of the columnar honeycomb filter can be shorter than the maximum diameter of each end face.

[0040] The shape of the cells in the cross-section perpendicular to the flow path direction of the cells is not restricted, but is preferably a quadrilateral, a hexagon, an octagon, or a combination thereof. Squares and hexagons are particularly preferred. By designing the cells in this way, it is possible to reduce the pressure loss when a fluid flows through the columnar honeycomb structure.

[0041] The upper limit of the average thickness of the partitions in the columnar honeycomb filter is, with regard to suppressing pressure loss, preferably 0.238 mm or less, more preferably 0.228 mm or less, and even more preferably 0.220 mm or less. However, with regard to ensuring the strength of the columnar honeycomb filter, the lower limit of the average thickness of the partitions is preferably 0.194 mm or more, more preferably 0.204 mm or more, and even more preferably 0.212 mm or more. In this description, the partition thickness refers to the length of a line segment passing through the partition when the centroids of adjacent cells are connected by this line segment in a cross-section perpendicular to the direction in which the cells extend. The average partition thickness refers to the mean thickness of all partitions.

[0042] The cell density (number of cells per unit cross-sectional area perpendicular to the direction in which the cells extend) is not particularly limited, but can range, for example, from 6 to 2000 cells / square inch (0.9 to 311 cells / cm²). 2 ), more preferably 50 to 1000 cells / square inch (7.8 to 155 cells / cm²) 2 ), particularly preferably 100 to 400 cells / square inch (15.5 to 62.0 cells / cm²). 2 ).

[0043] The columnar honeycomb filter can be supplied as a single-piece product. Alternatively, it can be supplied as a segmented assembly by connecting and integrating multiple columnar honeycomb filter segments at their side faces, each segment having an outer circumferential side wall. Supplying the columnar honeycomb filter as a segmented assembly improves its thermal shock resistance. <2. Method for producing a columnar honeycomb structure filter>

[0044] A process for manufacturing a columnar honeycomb filter is described below by way of example. First, a green body is formed by kneading a raw material composition comprising a ceramic raw material, a dispersion medium, a pore-forming material, and a binder. Next, the green body is subjected to extrusion to produce a columnar honeycomb filter body as desired. Additives such as a dispersant can be added to the raw material composition as needed. For extrusion, a die with a desired overall shape, cell shape, partition thickness, cell density, and the like can be used.

[0045] After the columnar honeycomb mold has dried, plugged sections are formed at predetermined positions on both end faces of the columnar honeycomb mold. These plugged sections are then dried to create a columnar honeycomb mold with plugged sections. A columnar honeycomb structure is then obtained by degreasing and firing the columnar honeycomb mold. Finally, a columnar honeycomb filter is obtained by forming porous films on the surface of the first cells of the columnar honeycomb structure.

[0046] A ceramic raw material is a residue that remains after firing and forms part of the framework of the honeycomb structure. Any material capable of forming the aforementioned ceramics after firing can be used as a ceramic raw material. The ceramic raw material may be provided in powder form, for example. Examples of ceramic raw materials include cordierite, mullite, zirconium, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, indialite, sapphire, corundum, titanium oxide, and the like. Specific examples include, but are not limited to, silicon dioxide, talc, aluminum oxide, kaolin, serpentine, pyrophyllite, brucite, boehmite, mullite, magnesite, aluminum hydroxide, and the like. A single type of ceramic raw material can be used alone, or two or more types can be used in combination.

[0047] For filter applications such as DPFs and GPFs, cordierite can be a preferred ceramic material. In this case, a cordierite-forming raw material can be used. A cordierite-forming raw material is a material that transforms into cordierite through firing. It is desirable that the cordierite-forming raw material has a chemical composition of aluminum oxide (Al₂O₃) (including the amount of aluminum hydroxide that is converted to aluminum oxide): 30 to 45 wt%, magnesium oxide (MgO): 11 to 17 wt%, and silicon dioxide (SiO₂): 42 to 57 wt%.

[0048] Examples of the dispersion medium include water or a mixed solvent of water with an organic solvent such as alcohol, and water may be particularly preferred.

[0049] The pore-forming material is not particularly restricted, as long as it becomes pores after firing, and examples include wheat flour, starch, foamed resin, water-absorbing resin, porous silicon dioxide, carbon (e.g., graphite), ceramic balloon, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic, phenol, and the like. One type of pore-forming material may be used alone, or two or more types may be used in combination. With a view to increasing the porosity of the fired body, the amount of pore-forming material is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the ceramic raw material.With regard to ensuring the strength of the fired body, the amount of pore-forming material is preferably 10 parts by mass or less, more preferably 7 parts by mass or less and even more preferably 4 parts by mass or less in relation to 100 parts by mass of the ceramic raw material.

[0050] Examples of the binder include organic binders such as methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. It is particularly preferred to use methylcellulose and hydroxypropylmethylcellulose in combination. Furthermore, to increase the strength of the honeycomb-shaped body, the amount of binder is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 6 parts by mass or more, based on 100 parts by mass of the ceramic raw material. To suppress the occurrence of cracks due to abnormal heat generation during the firing step, the amount of binder is preferably 9 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, based on 100 parts by mass of the ceramic raw material.One type of binder can be used alone, or two or more types can be used in combination.

[0051] Suitable dispersants include ethylene glycol, dextrin, fatty acid soap, polyether polyol, and the like. A single dispersant may be used alone, or two or more types may be used in combination. The dispersant content is preferably 0 to 2 parts by weight per 100 parts by weight of the ceramic raw material.

[0052] The method for plugging the end faces of the columnar honeycomb mold is not particularly restricted, and a known method may be used. The material of the plugged section is not particularly restricted; however, ceramics are preferred with regard to strength and heat resistance. The ceramic material is preferably one containing at least one material selected from the following group: cordierite, mullite, zirconium, aluminum titanate, silicon carbide, silicon nitride, zirconium oxide, spinel, indialite, sapphire, corundum, and titanium oxide. It is even more preferred that the plugged section have the same material composition as the main body section of the honeycomb mold, since the coefficient of thermal expansion during firing can be the same, thus improving durability.

[0053] After drying the honeycomb mold, a columnar honeycomb structure can be produced by degreasing and firing. Regarding the drying, degreasing, and firing processes, known conditions based on the material composition of the honeycomb mold can be used, requiring no further explanation. However, specific examples of these conditions are given below.

[0054] Conventional drying processes such as hot gas drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze-drying can be used in the drying process. Among these, a drying process that combines hot gas drying with microwave drying or dielectric drying is preferred because the entire molded body can be dried quickly and uniformly.

[0055] When forming the plugged sections, it is preferred to form the plugged sections on both end faces of the dried honeycomb mold and then dry the plugged sections. The plugged sections are formed at predetermined positions such that several first cells, extending from the inlet-side end face to the outlet-side end face, each having an opening on the inlet-side end face and a closed section on the outlet-side end face, and several second cells, extending from the inlet-side end face to the outlet-side end face, each having a blocked section on the inlet-side end face and an opening on the outlet-side end face, are arranged alternately adjacent to each other with a porous partition between them.

[0056] Next, the degreasing process is described. The combustion temperature of the binder is approximately 200 °C, and the combustion temperature of the pore-forming material is approximately 300 to 1000 °C. Therefore, the degreasing process can be carried out by heating the honeycomb mold body to a temperature in the range of approximately 200 to 1000 °C. The heating time is not particularly limited but is typically about 10 to 100 hours. The honeycomb mold body after the degreasing step is called a calcined body.

[0057] The firing process depends on the material composition of the honeycomb body, but can, for example, be carried out by heating the calcined body to 1350 to 1600 °C and holding it at that temperature for 3 to 10 hours. In this way, a columnar honeycomb structure can be produced, comprising several first cells extending from the inlet-side end face to the outlet-side end face, each opening at the inlet-side end face and having a closed section at the outlet-side end face, and several second cells extending from the inlet-side end face to the outlet-side end face, each having a closed section at the inlet-side end face and opening at the outlet-side end face, wherein the several first cells and the several second cells are arranged alternately adjacent to each other with a porous partition between them.

[0058] Next, a porous film is formed on the surface of the first cells of the columnar honeycomb structure that has undergone the firing process. This is achieved by first applying ceramic particles to a surface of the first cells. An aerosol containing the ceramic particles is then ejected towards the inlet-side end face, preferably towards the center of the inlet-side end face, from a direction perpendicular to the inlet-side end face, while a suction force is applied to the outlet-side end face to draw the ejected aerosol away. For example, the distance between the aerosol ejection nozzle and the inlet-side end face can be from 500 mm to 2000 mm, and the aerosol ejection velocity can be from 2 to 80 m / s.

[0059] It is desirable for the ceramic particles in the aerosol to exhibit low aggregation. Regarding the ceramic particles in the aerosol, those of 10 µm or larger preferably constitute 20 vol% or less, more preferably 18 vol% or less, and even more preferably 15 vol% or less, in a volume-based particle diameter frequency distribution measured by a laser diffraction / laser scattering method. By suppressing the aggregation of the ceramic particles in the aerosol, it becomes possible to deposit the ceramic particles with a desired particle diameter distribution on the surface of the first cells, and the quality stability can be improved. Furthermore, since aggregation is suppressed, it becomes easier to deposit fine ceramic particles, thus making it possible to reduce the average pore diameter of the porous films.

[0060] Regarding the ceramic particles in the aerosol, the median diameter (D50) in a volume-based cumulative particle diameter distribution, measured by a laser diffraction / laser scattering method, is preferably 1.0 to 6.0 µm, more preferably 2.0 to 5.0 µm. By ejecting extremely fine ceramic particles, it is possible to increase the porosity while simultaneously reducing the average pore diameter of the resulting porous films.

[0061] The ceramic particles used are those mentioned above, which form the porous film. For example, ceramic particles comprising one, two, or more materials selected from the following group can be used: cordierite, silicon carbide (SiC), talc, mica, mullite, clay shards, aluminum titanate, aluminum oxide, silicon nitride, sialon, zirconium phosphate, zirconium dioxide, titanium dioxide, and silicon dioxide. The main component of the ceramic particles is preferably silicon carbide, aluminum oxide, silicon dioxide, cordierite, or mullite. The main component of the ceramic particles refers to a component that comprises 50 wt% or more of the ceramic particles. The ceramic particles preferably comprise 50 wt% or more, more preferably 70 wt% or more, and even more preferably 90 wt% or more SiC.

[0062] To suppress the aggregation of ceramic particles, it is advantageous to carry out the aerosol emission using an aerosol generator comprising a drive gas flow path for guiding a pressurized drive gas, a feed port provided along the drive gas flow path that can draw the ceramic particles from an outer circumferential side of the drive gas flow path to an inner side of the drive gas flow path, and a nozzle located at a tip of the drive gas flow path that can eject the aerosol. In one embodiment, the feed port can be configured such that the ceramic particles are introduced into the drive gas flow path from a direction that is substantially perpendicular to the flow direction of the drive gas flowing through the drive gas flow path.

[0063] As the ceramic particles are introduced into the propellant gas flow path, they can aggregate. Fine ceramic particles, in particular, tend to aggregate. However, if the ceramic particles are fed from the outer circumferential side of the propellant gas flow path to the inner side, the propellant gas exerts a strong loosening effect on the ceramic particles, so that it is assumed the ceramic particles can be ejected from the aerosol generator nozzle with suppressed aggregation. Some examples are described below with reference to the figures. Fig. 5a and Fig. 5c as well Fig. 4b falls under the wording of the independent claims. The other variants are helpful for understanding the invention. (First embodiment of the aerosol generator)

[0064] Fig.Figure 4A schematically shows a first embodiment of an aerosol generator (410) suitable for emitting ceramic particles in which aggregation is suppressed.

[0065] The aerosol generator (410) includes: a propellant gas flow path (417) for guiding a pressurized propellant gas, a supply port (417i) which is provided along the path of the drive gas flow path (417) and which can draw the ceramic particles (412) from an outer circumferential side of the drive gas flow path (417) to an inner side of the drive gas flow path (417), a nozzle (411) which is attached to a tip of the propulsion gas flow path (417) and can eject the aerosol, a cylinder (413) for receiving the ceramic particles (412), a piston or screw (414) for expelling the ceramic particles (412) received in the cylinder (413) from a cylinder outlet (413e), and a loosening chamber (415) comprising an inlet (415i) connected to the cylinder outlet (413e), a rotating body (416) for loosening the ceramic particles (412) discharged from the cylinder outlet (413e) and an outlet (415e) connected to the feed port (417i).

[0066] The aerosol generator (410) can emit aerosol from the nozzle (411). Ceramic particles (412), which are set to a predetermined particle diameter distribution, are contained in the cylinder (413). The ceramic particles (412) contained in the cylinder (413) are forced out of the cylinder outlet (413e) by a piston or a screw (414). The piston or screw (414) can be designed to adjust the release rate of the ceramic particles (412). The ceramic particles (412) ejected from the cylinder outlet (413e) enter the aeration chamber (415) via the inlet (415i). In this embodiment, the cylinder outlet (413e) and the inlet (415i) are common.

[0067] The ceramic particles (412) introduced into the loosening chamber (415) move within the chamber while being loosened by the rotating body (416) and are discharged from the loosening chamber outlet (415e). The rotating body (416) can be, for example, a rotating brush. The rotating body (416) can be driven by a motor and can be designed to control its rotational speed.

[0068] The ceramic particles (412) discharged from the loosening chamber outlet (415e) are drawn into the drive gas flow path (417) from the outer circumferential side of the drive gas flow path (417) via the supply port (417i). In the present embodiment, the loosening chamber outlet (415e) and the supply port (417i) are common. Furthermore, in the present embodiment, the ceramic particles (412) are introduced into the drive gas flow path (417) from a direction that is substantially perpendicular to the flow direction of the drive gas flowing through the drive gas flow path (417). The ceramic particles (412) introduced into the propulsion gas flow path (417) collide with the propulsion gas flowing through the propulsion gas flow path (417) and are mixed as they are loosened to form an aerosol and are ejected from the nozzle (411).In the present embodiment, the ceramic particles (412) loosened by passing through the loosening chamber (415) are introduced from the supply port (417i) into the drive gas flow path (417). Therefore, in addition to the loosening effect of the ceramic particles (412) due to the impacts with the drive gas, the loosening effect of the ceramic particles (412) in the loosening chamber (415) can also be achieved, resulting in a strong aggregation suppression effect. The nozzle (411) is preferably installed in a position and orientation in which the aerosol is ejected in a direction perpendicular to the inlet-side end face of the columnar honeycomb structure. More preferably, the nozzle (411) is installed in a position and orientation in which the aerosol is ejected in a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face.

[0069] By using a compressed gas, such as compressed air with a controlled pressure, as the propellant gas, the discharge rate of the aerosol from the nozzle (411) can be controlled. Dry air (e.g., with a dew point of 10 °C or less) is preferably used as the propellant gas to suppress the aggregation of the ceramic particles. In this description, "dew point" refers to a value measured by a polymer-type capacitive dew point meter according to JIS Z8806:2001.

[0070] The lower limit of the flow velocity of the driving gas immediately before it flows through the supply port (417i) of the driving gas flow path (417) is preferably 9 m / s or more, more preferably 10 m / s or more, and even more preferably 11 m / s or more, with a view to increasing the loosening force of the ceramic particles. The upper limit of the flow velocity of the driving gas immediately before it flows through the supply port (417i) of the driving gas flow path (417) is not specifically defined, but is usually 15 m / s or less, and typically 13 m / s or less. If necessary, the driving gas flow path (417) can be provided with a Venturi section, which will be described later, on the upstream side of the supply port (417i).

[0071] Fine ceramic particles have the property of aggregating easily. However, by using the aerosol generator (410) according to the present embodiment, it is possible to emit ceramic particles with a target particle diameter distribution in which aggregation is suppressed. (Second embodiment of the aerosol generator)

[0072] Fig. Figure 4B schematically shows a second embodiment of an aerosol generator (420) suitable for emitting ceramic particles in which aggregation is suppressed.

[0073] The aerosol generator (420) includes: a propulsion gas flow path (427) for guiding a pressurized propulsion gas, a supply port (427i) which is provided along the path of the drive gas flow path (427) and which can draw the ceramic particles (422) from an outer circumferential side of the drive gas flow path (427) to an inner side of the drive gas flow path (427), a nozzle (421) which is attached to a tip of the propulsion gas flow path (427) and can eject the aerosol, a flow path (423) for drawing in and transporting the ceramic particles (422), which includes an outlet (423e) that is connected to the feed port (427i), and a receiving unit (429) for receiving the ceramic particles (422) and for supplying the ceramic particles (422) to the flow path (423) for suction and transport.

[0074] For example, a funnel can be used for the receiving unit (429). Ceramic particles, configured with a predetermined particle diameter distribution, are contained in the receiving unit (429). The ceramic particles (422) contained in the receiving unit (429) receive suction from the drive gas flow path (427) and flow through the outlet (429e) provided at the bottom of the receiving unit (429). After being transported through the flow path (423) to the outlet (423e), they are introduced from the feed port (427i) into the drive gas flow path (427). At this point, the ambient gas (typically air), which is drawn from the inlet (429i) of the receiving unit inlet, is introduced into the drive gas flow path (427) along with the ceramic particles (422) through the flow path (423). In the present embodiment, the outlet (423e) and the supply port (427i) are common.Furthermore, in the present embodiment, the ceramic particles (422) are introduced into the drive gas flow path (427) from a direction that is essentially perpendicular to the flow direction of the drive gas flowing through the drive gas flow path (427).

[0075] The ceramic particles (422) introduced into the drive gas flow path (427) collide with the drive gas flowing through the drive gas flow path (427) and are mixed as they are loosened to form an aerosol, and are then ejected from the nozzle (421). The nozzle (421) is preferably installed in a position and orientation such that the aerosol is ejected in a direction perpendicular to the inlet-side end face of the columnar honeycomb structure. More preferably, the nozzle (421) is installed in a position and orientation such that the aerosol is ejected in a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face.

[0076] The feed of the ceramic particles (422) into the receiving unit (429) is not restricted, but is preferably carried out using, for example, a powder metering conveyor (4211) such as a screw conveyor and a belt conveyor. The ceramic particles (422) discharged from the powder metering conveyor (4211) can fall into the receiving unit (429) by gravity.

[0077] In a preferred embodiment, the drive gas flow path (427) includes a Venturi section (427v) in which the flow path is constricted, and the supply port (427i) is provided on the downstream side of the narrowest point of the flow path in the Venturi section (427v). When the drive gas flow path (427) has a Venturi section (427v), the velocity of the drive gas flowing through the Venturi section (427v) increases. Therefore, the drive gas can be made to collide with the ceramic particles (422) supplied downstream of the Venturi section (427v) at a higher velocity, thus improving the loosening force. To increase the loosening force of the propellant gas, it is more preferred that the supply port (427i) is provided on the downstream side of the narrowest flow path point in the Venturi section (427v) and adjacent to this point.The configuration can be realized, for example, by connecting the drive gas flow path (427) and the flow path (423) for intake and transport using a Venturi ejector (4210).

[0078] The lower limit of the flow velocity of the driving gas immediately before passing through the Venturi section (427v) is preferably 13 m / s or more, more preferably 20 m / s or more, and even more preferably 26 m / s or more, with a view to increasing the loosening force on the ceramic particles. The upper limit of the flow velocity of the driving gas immediately before passing through the Venturi section (427v) is not specifically defined, but is normally 50 m / s or less, and typically 40 m / s or less.

[0079] The lower limit of the ratio of the flow path cross-sectional area immediately upstream of the Venturi section to the flow path cross-sectional area of ​​the Venturi section is preferably 8 or more, and more preferably 16 or more, with a view to increasing the loosening force. The upper limit of the ratio of the flow path cross-sectional area immediately upstream of the Venturi section to the flow path cross-sectional area of ​​the Venturi section is not particularly restricted, but if it is too large, the pressure drop across the Venturi section increases, so that it is preferably 64 or less, and more preferably 32 or less. Here, the flow path cross-sectional area of ​​the Venturi section means the flow path cross-sectional area of ​​the narrowest point in the Venturi section.Furthermore, the flow path cross-sectional area immediately before the Venturi section means the flow path cross-sectional area on the upstream side of the Venturi section, immediately before the flow path narrows.

[0080] For example, by using the Venturi ejector (4210), when the propellant gas flows through the propellant gas flow path (427), a strong suction force can be exerted on the intake and transport flow path (423), thus preventing the intake and transport flow path (423) from becoming clogged by the ceramic particles (422). The Venturi ejector (4210) is also effective in removing the ceramic particles (422) if the intake and transport flow path (423) becomes clogged with them.

[0081] By using a compressed gas, such as compressed air with a controlled pressure, as the propellant gas, the discharge rate of the aerosol from the nozzle (421) can be controlled. Dry air (e.g., with a dew point of 10 °C or less) is preferably used as the propellant gas to suppress the aggregation of the ceramic particles.

[0082] Fine ceramic particles have the property of aggregating easily. However, by using the aerosol generator (420) according to the present embodiment, it is possible to emit ceramic particles with a target particle diameter distribution with suppressed aggregation. (Third embodiment of the aerosol generator)

[0083] Fig. Figure 4C schematically shows a third embodiment of an aerosol generator (430) suitable for emitting ceramic particles in which aggregation is suppressed.

[0084] The aerosol generator (430) includes: a propulsion gas flow path (437) for guiding a pressurized propulsion gas, a supply port (437i) which is provided along the path of the drive gas flow path (437) and which can draw the ceramic particles (432) from an outer circumferential side of the drive gas flow path (437) to an inner side of the drive gas flow path (437), a nozzle (431) which is attached to a tip of the propulsion gas flow path (437) and can eject the aerosol, a flow path (433) for drawing in and transporting the ceramic particles (432), which has an outlet (433e) that is connected to the supply port (437i), a belt conveyor (434) for transporting the ceramic particles (432), and a loosening chamber (435) comprising an inlet (435in) for receiving the ceramic particles (432) transported by the belt conveyor (434), a rotating body (436) for loosening the received ceramic particles (432) and an outlet (435e) connected to the flow path (433) for suction and transport.

[0085] The aerosol generator (430) can include a receiving unit (439), such as a container for receiving the ceramic particles (432). The receiving unit (439) contains ceramic particles that are configured with a predetermined particle diameter distribution. The ceramic particles (432) in the receiving unit (439) are stirred by the stirrer (438). As a result, the ceramic particles, which are prone to bridging, can be dispensed stably from the discharge port (439e). A discharge port (439e) for ceramic particles (432) is provided at the bottom of the receiving unit (439). The ceramic particles (432) discharged from the discharge port (439e) are transported by the belt conveyor (434) to the inlet (435in) of the aeration chamber (435). The transport speed of the ceramic particles (432) can be adjusted by controlling the belt speed of the belt conveyor (434).

[0086] The ceramic particles (432) introduced into the loosening chamber (435) move within the loosening chamber (435) while being loosened by the rotating body (436) and are discharged from the loosening chamber outlet (435e). A rotating brush, for example, can be used as the rotating body (436). The rotating body (436) can be driven by a motor and can be designed to control its rotational speed.

[0087] In response to the suction force from the drive gas flow path (437), the transport gas for the ceramic particles (432) is drawn in from the inlet (433i) of the flow path (433) for suction and transport. Ambient gas such as air can be used as the transport gas, but it is preferred to use dry air (for example, with a dew point of 10 °C or less) to suppress the aggregation of the ceramic particles. Furthermore, the transport gas can be transported solely by suction from the drive gas flow path (437) or it can be conveyed using a compressor or the like. The ceramic particles (432) discharged from the loosening chamber outlet (435e) are entrained by the transport gas flowing through the flow path (433) and transported to the outlet (433e) and then introduced into the drive gas flow path (437) via the feed port (437i).In the present embodiment, the outlet (433e) and the supply port (437i) are common. Furthermore, in the present embodiment, the ceramic particles (432) are introduced into the drive gas flow path (437) from a direction that is substantially perpendicular to the flow direction of the drive gas flowing through the drive gas flow path (437).

[0088] The ceramic particles (432) supplied to the drive gas flow path (437) along with the transport gas collide with the drive gas flowing through the drive gas flow path (437) and are mixed as they are loosened to form an aerosol, and are then ejected from the nozzle (431). In the present embodiment, the ceramic particles (432) loosened by passing through the loosening chamber (435) are introduced into the drive gas flow path (437) via the supply port (437i). Therefore, in addition to the effect of the drive gas loosening the ceramic particles (432), the loosening effect of the loosening chamber (435) can also be achieved, resulting in a strong aggregation suppression effect.The nozzle (431) is preferably installed in a position and orientation in which the aerosol is ejected in a direction perpendicular to the inlet-side end face of the columnar honeycomb structure. More preferably, the nozzle (431) is installed in a position and orientation in which the aerosol is ejected in a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face.

[0089] In a preferred embodiment, the drive gas flow path (437) includes a Venturi section (437v) in which the flow path is constricted, and the supply port (437i) is provided on the downstream side of the narrowest point of the flow path in the Venturi section (437v). To increase the loosening force of the drive gas, it is more preferred that the supply port (437i) be provided on the downstream side of the narrowest point of the flow path in the Venturi section (437v) and adjacent to this point. When the drive gas flow path (437) has a Venturi section (437v), the velocity of the drive gas flowing through the Venturi section (437v) increases. Therefore, propellant gas can be made to collide with the ceramic particles (432) supplied downstream of the Venturi section (437v) at a higher speed, thus improving the loosening force.The configuration can be realized, for example, by connecting the drive gas flow path (437) and the flow path (433) for intake and transport using a Venturi ejector (4310).

[0090] The lower limit of the flow velocity of the driving gas immediately before passing through the Venturi section (437v) is preferably 13 m / s or more, more preferably 20 m / s or more, and even more preferably 26 m / s or more, with a view to increasing the loosening force on the ceramic particles. The upper limit of the flow velocity of the driving gas immediately before passing through the Venturi section (437v) is not specifically defined, but is normally 50 m / s or less, and typically 40 m / s or less.

[0091] The lower limit of the ratio of the flow path cross-sectional area immediately upstream of the Venturi section to the flow path cross-sectional area of ​​the Venturi section is preferably 8 or more, and more preferably 16 or more, with a view to increasing the loosening force. The upper limit of the ratio of the flow path cross-sectional area immediately upstream of the Venturi section to the flow path cross-sectional area of ​​the Venturi section is not particularly restricted, but if it is too large, the pressure drop across the Venturi section increases, so that it is preferably 64 or less, and more preferably 32 or less. Here, the flow path cross-sectional area of ​​the Venturi section means the flow path cross-sectional area of ​​the narrowest point in the Venturi section.Furthermore, the flow path cross-sectional area immediately before the Venturi section means the flow path cross-sectional area on the upstream side of the Venturi section, immediately before the flow path narrows.

[0092] For example, by using the Venturi ejector (4310), when the propellant gas flows through the propellant gas flow path (437), a strong suction force can be exerted on the intake and transport flow path (433), thus preventing the intake and transport flow path (433) from becoming clogged by the ceramic particles (432). The Venturi ejector (4310) is also effective in removing the ceramic particles (432) if the intake and transport flow path (433) becomes clogged with them.

[0093] By using a compressed gas, such as compressed air with a controlled pressure, as the propellant gas, the discharge rate of the aerosol from the nozzle (431) can be controlled. As with the transport gas, dry air is preferably used as the propellant gas.

[0094] Fine ceramic particles have the property of aggregating easily. However, by using the aerosol generator (420) according to the present embodiment, it is possible to emit ceramic particles with a target particle diameter distribution with suppressed aggregation. (Aerosol generator according to comparison example)

[0095] Fig. Figure 4D schematically shows an aerosol generator (610) according to a comparative example.

[0096] The in Fig. The aerosol generator shown in 4D (610) includes: a nozzle (614) for ejecting an aerosol containing a propellant gas and ceramic particles from an ejection port (614e), a tube (615) for drawing in and transporting ceramic particles (622), which has an outlet (615e) for the ceramic particles at one end, wherein the outlet (615e) is connected to an inlet (614in) of the nozzle (614), a gas flow path (616) for guiding propellant gas, which is formed coaxially on an outer circumference of the tube (615), such that an outlet (616e) of the propellant gas is connected to an inlet (614in) of the nozzle (614), and a receiving unit (629) for receiving the ceramic particles (622) and feeding the ceramic particles (622) to the tube (615) for suction and transport.

[0097] The gas flow path (616) is formed between the outer circumferential surface (619) of the tube (615) and the coaxial inner wall surface (617), which has a larger diameter than the outer circumferential surface (619) of the tube (615). The upstream side of the gas flow path (616) is connected to an inlet tube (618), and the motive gas can flow through the inlet tube (618) into the gas flow path (616). The motive gas flowing into the gas flow path (616) changes its flow direction by 90° and moves towards a motive gas outlet (616e). The inner wall surface (617) has a cylindrical section (617a) with a constant diameter and a tapered section (617b) which is connected to the downstream side of the cylindrical section (617a) and whose diameter gradually decreases towards the outlet (616e).The outer circumferential surface (619) of the tube (615) has a cylindrical section (619a) with a constant outer diameter, a diameter-expanded section (619b) with an expanded outer diameter, which is connected to the downstream side of the cylindrical section (619a), and a tapered section (619c) whose outer diameter gradually decreases towards the outlet (615e) and which is connected to the downstream side of the diameter-expanded section (619b).

[0098] Near the propulsion gas outlet (616e), the space between the tapered section (617b) of the inner wall surface (617) and the tapered section (619c) of the outer circumferential surface (619) of the tube (615) is reduced, thus narrowing the gas flow path (616). In this configuration, the accelerated propulsion gas flows from the outlet (616e) of the gas flow path (616) towards the nozzle (614).

[0099] Upstream of the tube (615), ceramic particles, configured with a predetermined particle diameter distribution, are collected in the receiving unit (629). For example, a funnel can be used for the receiving unit (629). The ceramic particles (622) in the receiving unit (629) are drawn into the tube (615) from an outlet (629e) provided at the bottom of the receiving unit (629) by the suction force generated by the driving gas, which flows forcefully from the outlet (616e) of the gas flow path (616) to the inlet (614in) of the nozzle (614). At the same time, the ambient gas (typically air) is also drawn in along with the ceramic particles (622) from the inlet (629i) of the receiving unit and flows through the tube (615). Afterwards, the ceramic particles (622) are released together with the ambient gas from the outlet (615e) of the tube (615) and mixed with the propellant gas.The ceramic particles (622) are then carried along by the propellant gas, pass through the interior of the nozzle (614) and are ejected as an aerosol from the ejection port (614e).

[0100] The supply of the ceramic particles (622) to the receiving unit (629) is not restricted, but can be carried out, for example, using a powder metering conveyor (6211) such as a screw conveyor or a belt conveyor. The ceramic particles (622) dispensed from the powder metering conveyor (6211) can fall into the receiving unit (629) by gravity.

[0101] The nozzle (614) has a constriction section (614b) with a constant inner diameter and a diffuser section (614a) connected to the downstream side of the constriction section (614b), the inner diameter of which gradually increases towards the discharge port (614e). Mixing of the ceramic particles and the propellant gas is promoted at the constriction section (614b), and the pressure is increased at the diffuser section (614a). The aerosol containing the propellant gas and the ceramic particles is then discharged from the discharge port (614e).

[0102] The aerosol generator (610) according to the comparative example uses a Coanda-type ejector. In the aerosol generator (610) according to the comparative example, unlike the aerosol generator according to the embodiments of the present invention, the flow direction of the ceramic particles when the ceramic particles collide with the driving gas is substantially parallel to the flow direction of the driving gas. Furthermore, unlike the aerosol generator according to the embodiments of the present invention, the aerosol generator (610) according to the comparative example is designed such that the driving gas collides with the ceramic particles from the outer circumferential side of the flow of the ceramic particles. As a result, it is assumed that the impact energy becomes small when the driving gas collides with the ceramic particles, so that the loosening force becomes weak and the ceramic particles are likely to be ejected from the nozzle (614) in an aggregated state. (First embodiment of the device for attaching particles)

[0103] Fig. Figure 5A schematically shows a device configuration of a first embodiment of the device for attaching particles (510) which is suitable for carrying out the step of attaching ceramic particles to the surface of the first cells of the columnar honeycomb structure.

[0104] The device for attaching particles (510) comprises: a holder (514) for holding a columnar honeycomb structure (500), a blower (512) for applying a suction force to the outlet-side end face (506) of the columnar honeycomb structure (500), an aerosol generator (511) for ejecting an aerosol containing ceramic particles in the direction of the inlet-side end face (504) from a direction perpendicular to the inlet-side end face (504) and for attaching the ceramic particles to a surface of the first cells, and a chamber (513) which is provided between a nozzle (511a) of the aerosol generator (511) and the inlet-side end face (504) to guide the aerosol through its interior.

[0105] The holder (514) is designed to hold the columnar honeycomb structure (500) in a position where the inlet-side end face (504) of the nozzle (511a) of the aerosol generator (511) faces the nozzle (511a), with the inlet-side end face (504) exposed. For example, the holder (514) can have a clamping mechanism (514b) for gripping the outer circumferential side wall (502). The clamping mechanism is not particularly limited and a balloon clamping chuck can be cited as an example. The holder (514) has a housing (514a) for straightening the aerosol that has passed through the columnar honeycomb structure (500) in one direction without diffusion.

[0106] The side wall (513d) of the chamber (513) can be in a tubular shape, such as a cylindrical or polygonal tube. The chamber (513) has a surface (513a) opposite the inlet-side end face (504). This surface (513a) opposite the inlet-side end face (504) has an inlet port (513b) for the nozzle (511a) of the aerosol generator (511). With this configuration, the aerosol emitted from the aerosol generator (511) can be introduced directly into the chamber (513). Typically, the downstream end (513e) of the side wall (513d) of the chamber (513) is connected to the holder (514) and the opposite surface (513a) to the inlet-side end face (504) is provided at the upstream end (513f) opposite the downstream end (513e) of the side wall (513d) of the chamber (513).

[0107] An opening (513c) for the introduction of ambient gas can be provided on the side wall (513d) and / or the surface opposite (513a) to the inlet-side end face (504). This allows the flow rate of the gas flowing into the chamber (513) to be adjusted according to the suction force from the blower (512). However, as described in Fig.Figure 5A shows, preferably, that the side wall (513d) of the chamber (513) is not provided with an opening (513c) for admitting ambient gas and that the ambient gas flowing into the chamber (513) is received only from the opening (513c) provided on the surface (513a) opposite the inlet-side end face (504). In one embodiment, a die-cut plate and / or a nonwoven fabric can be used for the surface (513a) opposite the inlet-side end face (504). Furthermore, a filter (513g) can be installed in the opening (513c) to entrain aggregated powder, honeycomb fragments, and dust.

[0108] If the cross-sectional area of ​​the aerosol flow path through the chamber (513) is larger than the size of the inlet-side end face (504), a tapered section (513h) can be provided at the downstream end (513e) of the side wall (513d) so that the cross-sectional area of ​​the flow path gradually decreases towards the inlet-side end face (504). It is preferred that the contour of the cross-sectional area of ​​the flow path formed by the tapered section (513h) at the downstream end section (513e) of the side wall (513d) coincides with the outer circumferential contour of the inlet-side end face (504). By providing the tapered section (513h), the ceramic particles are easily drawn into the inlet-side end face (504).

[0109] The distance L from the outlet of the nozzle (511a) to the inlet-side end face (504) of the columnar honeycomb structure (500) is preferably designed to correspond to the area A of the inlet-side end face (504) of the columnar honeycomb structure (500). In particular, it is preferred to increase the distance L (mm) as the area A (mm²) increases, so that the aerosol tends to spread uniformly in the direction perpendicular to the flow direction of the aerosol.

[0110] By directing the ambient gas only from the opposite surface (513a) to the inlet-side end face (504), the ambient gas flows in the same direction as the flow direction of the sprayed aerosol. Therefore, the advantage is achieved that the aerosol is stable without disturbance. If, however, an opening (513c) is present in the side wall (513d) of the chamber (513), the ambient gas flowing in from the opening (513c) tends to be disruptive, which is disadvantageous because the aerosol flow becomes unstable. Therefore, in a preferred embodiment, the surface (513a) opposite the inlet-side end face (504) includes one or more openings (513c) for admitting ambient gas into the chamber (513) and includes no openings for admitting ambient gas into the chamber (513) other than those on the surface (513a) opposite the inlet-side end face.

[0111] The aerosol emitted from the aerosol generator (511) passes through the interior of the chamber (513) due to the suction force of the blower (512) and is then drawn into the first cells of the columnar honeycomb structure (500) by the inlet-side end face (504), which is held on the holder (514). The ceramic particles of the aerosol drawn into the first cells are deposited on the surface of the first cells.

[0112] The housing (514a) of the holder (514) has an outlet port (514e) on the downstream side of the outlet-side end face (506) of the columnar honeycomb structure (500). The outlet port (514e) is connected to an outlet tube (515), and a blower (512) is provided on the downstream side of this tube. As soon as the aerosol, from which the ceramic particles have been removed, is expelled from the outlet-side end face (506) of the columnar honeycomb structure (500), it flows through the exhaust tube (515) and is then expelled by the blower (512). A flow meter (516) is installed in the exhaust pipe (515) so that the gas flow rate measured by the flow meter (516) can be monitored and the power of the blower (512) can be controlled according to the gas flow rate.

[0113] As the process of depositing ceramic particles onto the surface of the first cells continues, the pressure drop between the inlet-side and outlet-side end faces of the columnar honeycomb structure increases with the increasing quantity of deposited ceramic particles. Therefore, by establishing a relationship between the quantity of deposited ceramic particles and the pressure drop in advance, it is possible to determine the endpoint of the depositing step based on the pressure drop. Thus, the particle depositing device (510) can be equipped with a differential pressure gauge (550) for measuring the pressure drop between the inlet-side end face (504) and the outlet-side end face (506) of the columnar honeycomb structure (500), and the endpoint of the step can be determined based on the differential pressure gauge reading.

[0114] When the step of applying the ceramic particles to the surface of the first cells is carried out, the ceramic particles are also applied to the inlet-side end face (504) of the columnar honeycomb structure (500). Therefore, it is preferred to remove the ceramic particles by suction with a vacuum or the like, while the inlet-side end face is leveled with a device such as a scraper.

[0115] The columnar honeycomb filter, in which the ceramic particles are attached to the surface of the first cells, is then heat-treated, for example, under conditions where it is held at a maximum temperature of 1000 °C or higher for 1 hour or more, typically between 1 hour and 6 hours, to complete the columnar honeycomb filter. The heat treatment can be carried out, for example, by placing a columnar honeycomb structure in an electric or gas furnace. The heat treatment bonds the ceramic particles together and fuses them to the partitions of the first cells, forming porous films on their surface.When heat treatment is carried out under oxygen-containing conditions such as air, a surface oxide film forms on the surface of the ceramic particles to promote bonding between them. This can result in porous films that are difficult to remove.

[0116] A laser diffraction-type particle diameter distribution measuring device (519) can be installed in the chamber (513). By installing a laser diffraction-type particle diameter distribution measuring device (519), the particle diameter distribution of the ceramic particles in the aerosol emitted by the aerosol generator (511) can be measured in real time. This makes it possible to monitor whether ceramic particles with a desired particle diameter distribution are being supplied to the columnar honeycomb structure.

[0117] With regard to improving the film thickness stability of the ceramic particles attached to the surface of the first cells, the average flow velocity of the aerosol flowing in the chamber (513) during the step of attaching the ceramic particles to the surface of the first cells is preferably 0.5 m / s to 3.0 m / s and more preferably 1.0 to 2.0 m / s.

[0118] From the perspective of improving the film thickness stability of the ceramic particles attached to the surface of the first cells, the lower limit of the average flow velocity of the aerosol flowing in the columnar honeycomb structure during the step of attaching the ceramic particles to the surface of the first cells is preferably 5 m / s or more, and more preferably 8 m / s or more. To further maintain high porosity of the porous films, the upper limit of the average flow velocity of the aerosol flowing in the columnar honeycomb structure is preferably 20 m / s or less, and more preferably 15 m / s or less. (Second embodiment of the device for attaching particles)

[0119] Fig.Figure 5B schematically shows a device configuration of a second embodiment of the particle application device (520), which is suitable for performing the step of applying ceramic particles to the surface of the first cells of a columnar honeycomb structure. The particle application device (520) according to the second embodiment differs from the particle application device (510) according to the first embodiment in that the openings (513c) for admitting ambient gas are provided on the side wall (513d) of the chamber (513), but not on the surface (513a) opposite the inlet-side end face (504).In the present embodiment, the openings (513c) are provided on the upstream side of the midpoint of a line segment m that connects the center of the outlet of the nozzle (511a) of the aerosol generator (511) with the center of the inlet-side end face (504) of the columnar honeycomb structure (500). For example, they are provided on the side wall (513d) near the upstream end (513f). The openings (513c) can be provided on the downstream side of the midpoint of the line segment m, but with a view to reducing the influence of the ambient gas introduced by the side wall on the dispersion of the sprayed aerosol, it is desirable to provide them on the upstream side as in this embodiment. Furthermore, in the present embodiment, several openings (513c) are provided at equal intervals along the circumferential direction of the side wall (513d).In the present embodiment, the device configuration is the same as in the first embodiment, except for the installation location of the openings (513c), and therefore the duplicate description is omitted. (Third embodiment of the device for attaching particles)

[0120] Fig.Figure 5C schematically shows a device configuration of a third embodiment of the particle application device (530), which is suitable for performing the step of applying ceramic particles to the surface of the first cells of a columnar honeycomb structure. In the particle application device (530) according to the third embodiment, the opposite surface (513a) of the chamber (513) has a concentric closure section (518) centered on the insertion port (513b). Furthermore, one or more openings (513c) for admitting ambient gas into the chamber (513) are provided on the outer circumferential side of the closure section (518). The method for forming the closure section (518) is not particularly restricted, but in one embodiment, a disk-shaped plate with an insertion port (513b) for the nozzle (511a) can be used.

[0121] By providing the closure section (518), the inflow of ambient gas from the vicinity of the nozzle (511a) of the aerosol generator (511) is prevented. On the other hand, ambient gas flows in from the vicinity of the side wall (513d) of the chamber (513). As a result, the aerosol ejected from the nozzle (511a) is drawn into the ambient gas flowing in from the opening (513c) and near the side wall (513d), thus providing the advantage that the aerosol tends to spread uniformly in the direction perpendicular to the aerosol flow direction. The closure section (518) can, for example, close off 50 to 87%, typically 70 to 80%, of the area of ​​the opposite surface (inner surface) (513a) of the chamber (513). Here, the area of ​​the opposite surface (inner surface) (513a) is the area that includes the insertion port (513b) and the openings (513c) in addition to the non-opening section.In the present embodiment, the device configuration is the same as that of the first embodiment, with the exception of the closure section (518), and thus the duplicate description is omitted. Examples

[0122] Examples are illustrated below to better understand the present invention and its advantages, but the present invention is not limited to these examples. <Beispiel 1> (1) Production of a columnar honeycomb structure

[0123] To 100 parts by mass of cordierite-forming raw material, 3 parts by mass of pore-forming material, 55 parts by mass of dispersion medium, 6 parts by mass of organic binder, and 1 part by mass of dispersant were added, mixed, and kneaded to produce a green body. The cordierite-forming raw material used was aluminum oxide, aluminum hydroxide, kaolin, talc, and silicon dioxide. Water was used as the dispersion medium, a water-absorbing polymer as the pore-forming material, hydroxypropyl methylcellulose as the organic binder, and fatty acid soap as the dispersant.

[0124] The green body was placed in an extrusion molding machine and extruded through a die with a predetermined shape to obtain a cylindrical honeycomb-shaped body. The resulting honeycomb body underwent dielectric drying and hot air drying, and then both end faces were trimmed to predetermined dimensions to produce a dried honeycomb body.

[0125] After being plugged with cordierite as material, so that the first and second cells were arranged alternately adjacent to each other, the resulting dried honeycomb body was degreased by heating to about 200 °C in an air atmosphere and further fired at 1420 °C for 5 hours in an air atmosphere, resulting in a columnar honeycomb structure. The specifications of the columnar honeycomb structure are as follows.

[0126] Overall shape: cylindrical shape with a diameter of 132 mm and a height of 120 mm

[0127] Cell shape in cross-section perpendicular to the cell flow path direction: square

[0128] Cell density (number of cells per unit cross-sectional area): 200 cpsi

[0129] Partition wall thickness: 0.2 mm (nominal value according to nozzle specification) (2) Attaching ceramic particles to a columnar honeycomb structure

[0130] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig.In the configuration shown in Figure 5A, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows. -Chamber Shape: cylindrical Inner diameter: 300 mm Length: 600 mm Ambient gas: Air Opening position for the introduction of ambient gas: only on the surface opposite the inlet-side end face of the columnar honeycomb structure. Structure of the opposite surface: punched plate Filter installation in the openings: Yes Position of the aerosol generator nozzle: center of the opposite surface Distance L from the nozzle outlet of the aerosol generator to the inlet-side end face of the columnar honeycomb structure: 600 mm -Aerosol generator Product name: RBG2000, manufactured by PALAS (with the in Fig. (4A structure shown) Type: Batch aerosol generator Rotating body: rotating brush Type of ceramic particles contained in the cylinder: SiC particles Volume-related particle diameter distribution of the ceramic particles contained in the cylinder (measured using laser diffraction / laser scattering methods): Median diameter (D50) = 3 µm, SiC particles with particle diameters from 10 µm: ≤ 20 vol.% Propellant gas: compressed dry air (dew point 10 °C or less) Presence / absence of the Venturi section: Absence Flow velocity of the propellant gas immediately before the propellant gas flows through the supply port of the propellant gas flow path: 15 m / s (measured with Anemomaster (manufacturer: KANOMAX model: 6162)) (all Anemomasters described below used this device.) Average flow velocity of the aerosol ejected from the nozzle: 20 m / s (measured with an Anemomaster at a position 10 to 20 mm downstream of the nozzle) Average flow rate of the aerosol ejected from the nozzle: 35 l / min (measured with a flow meter) Mass flow rate of ceramic particles in the aerosol ejected from the nozzle: 0.1 g / s (measured with a flow meter) Inner diameter of the aerosol generator nozzle: 8 mm -Laser diffraction-type measuring device for particle diameter distribution. Product name: Insitec Spray, manufactured by Malvern Installation location: inside the chamber -Operating conditions Suction flow rate of the blower: 4000 l / min Average flow velocity of the aerosol flowing in the chamber: 2 m / s (measured with Anemomaster) Average flow velocity of the aerosol flowing in the columnar honeycomb structure: approx. 10 m / s (calculated from flow rate / cell opening area) End point of the step to attach the ceramic particles: when the differential pressure reading reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies because the film mass is adjusted depending on the product volume). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0131] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0132] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0133] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter, obtained by the manufacturing process described above, were measured by SEM cross-sectional observation based on the procedure described above. The instrument used for the measurement was an FE-SEM (model: ULTRA55 (manufactured by ZEISS)) and the observation magnification was 1000x. Additionally, the measurement was performed in five or more arbitrary fields of view, and the average value was used as the measured value. HALCON version 11.0.5 from Lynx Co., Ltd. was used as the image analysis software. The results are shown in Table 1. (6) Quality stability

[0134] With regard to ten columnar honeycomb filters obtained by the above manufacturing process, the thickness of the porous films was investigated at a position 95 mm longitudinally from the centroid of the inlet-side end face of the columnar honeycomb filter, a section where the thickness of the porous films was likely to vary. The thickness was measured using a 3D measuring machine (model VR-3200 or VR-5200) manufactured by Keyence, and the coefficient of variation (= standard deviation / arithmetic mean) was determined. The results were evaluated as follows.

[0135] The results are shown in Table 1. A: The coefficient of variation was less than 0.20 B: The coefficient of variation was 0.21 or more and 0.40 or less C: The coefficient of variation exceeded 0.41 <Beispiel 2> (1) Production of a columnar honeycomb structure

[0136] Under the same manufacturing conditions as in Example 1, a columnar honeycomb structure was obtained.

[0137] (2) Attaching ceramic particles to the columnar honeycomb structure. The columnar honeycomb structure produced above was coated using the device for attaching particles with the Fig. In the configuration shown in Figure 5B, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows. -Chamber Shape: cylindrical Inner diameter: 300 mm Length: 600 mm Ambient gas: Air Opening position for letting in ambient gas: A stamped metal plate with an opening area of ​​50% was installed along the circumferential direction of the chamber side wall at a position (the position of the center of each opening) approximately 100 mm downstream from the upstream end of the chamber side wall. Filter installation in the openings: Yes Nozzle position of the aerosol generator: Center of the surface opposite the inlet-side front surface Distance L from the nozzle outlet of the aerosol generator to the inlet-side end face of the columnar honeycomb structure: 600 mm -Aerosol generator Product name: BEG1000, manufactured by PALAS (with the in Fig. (4C shown structure) Type: Continuous-type aerosol generator Connection method of the drive gas flow path and the flow path for intake and transport: Venturi ejector Location where the feed port for ceramic particles was installed: on the downstream side of the narrowest point of the Venturi section and adjacent to this point Transport speed of the ceramic particles through the belt conveyor: 1.0 g / s Rotating body: rotating brush Type of ceramic particles captured in the capture unit: SiC particles Volume-related particle diameter distribution of the ceramic particles captured in the capture unit (measured using laser diffraction / laser scattering methods): Median diameter (D50) = 3 µm, SiC particles with a particle diameter of 10 µm or more: ≤ 20 vol.% Propellant gas: compressed dry air (dew point 10 °C or less) Transport gas: compressed dry air (dew point 10 °C or less) Average flow rate of the transport gas before meeting the propulsion gas: 50 l / min (measured with a flow meter) Average flow rate of the propellant gas before meeting the transport gas: 100 l / min (measured with a flow meter) Flow velocity of the propellant gas immediately before the propellant gas flows through the Venturi section: 26 m / s (measured with Anemomaster) Ratio of the flow path cross-sectional area immediately before the Venturi section to the flow path cross-sectional area of ​​the Venturi section = 1:0.028 Average flow velocity of the aerosol ejected from the nozzle: 50 m / s (measured with an Anemomaster at a position 10 to 20 mm downstream of the nozzle) Average flow rate of the aerosol ejected from the nozzle: 150 l / min (measured with a flow meter) Mass flow rate of ceramic particles in the aerosol ejected from the nozzle: 0.5 g / s (measured with a flow meter) Inner diameter of the aerosol generator nozzle: 8 mm -Laser diffraction-type measuring device for particle diameter distribution. Product name: Insitec Spray, manufactured by Malvern -Operating conditions Suction flow rate of the blower: 4000 l / min Average flow velocity of the aerosol flowing in the chamber: 2 m / s (measured with Anemomaster) Average flow velocity of the aerosol flowing in the columnar honeycomb structure: approx. 10 m / s (calculated from flow rate / cell opening area) End point of the step to attach the ceramic particles: when the differential pressure reading reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies because the film mass is adjusted depending on the product volume). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0138] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0139] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0140] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0141] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <Beispiel 3> (1) Production of a columnar honeycomb structure

[0142] A columnar honeycomb structure was obtained under the same manufacturing conditions as in Example 1, except that the overall shape was changed to an elliptical cylindrical shape with a major axis of 231 mm, a minor axis of 106 mm and a height of 120 mm. (2) Attaching ceramic particles to a columnar honeycomb structure

[0143] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig. In the configuration shown in Figure 5A, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows. -Chamber Shape: cylindrical Inner diameter: 300 mm Length: 600 mm Ambient gas: Air Opening position for the introduction of ambient gas: only on the surface opposite the inlet-side end face of the columnar honeycomb structure. Structure of the opposite surface: punched plate Filter installation in the openings: Yes Position of the aerosol generator nozzle: center of the opposite surface Distance L from the nozzle outlet of the aerosol generator to the inlet-side end face of the columnar honeycomb structure: 600 mm -Aerosol generator Product name: BEG1000, manufactured by PALAS (with the in Fig. (4C shown structure) Type: Continuous-type aerosol generator Connection method of the drive gas flow path and the flow path for intake and transport: Venturi ejector Location where the feed port for ceramic particles was installed: on the downstream side of the narrowest point of the Venturi section and adjacent to this point Transport speed of the ceramic particles through the belt conveyor: 0.5 g / s Rotating body: rotating brush Type of ceramic particles captured in the capture unit: SiC particles Volume-related particle diameter distribution of the ceramic particles captured in the capture unit (measured using laser diffraction / laser scattering methods): Median diameter (D50) = 3 µm, SiC particles with a particle diameter of 10 µm or more: ≤ 20 vol.% Propellant gas: compressed dry air (dew point 10 °C or less) Transport gas: compressed dry air (dew point 10 °C or less) Average flow rate of the transport gas before meeting the propulsion gas: 80 l / min (measured with a flow meter) Average flow rate of the propellant gas before meeting the transport gas: 80 l / min (measured with a flow meter) Flow velocity of the propellant gas immediately before the propellant gas flows through the Venturi section: 26 m / s (measured with Anemomaster) Ratio of the flow path cross-sectional area immediately before the Venturi section to the flow path cross-sectional area of ​​the Venturi section = 1:0.05 Average flow velocity of the aerosol ejected from the nozzle: 18 m / s (measured with an Anemomaster at a position 10 to 20 mm downstream of the nozzle) Average flow rate of the aerosol ejected from the nozzle: 160 l / min (measured with a flow meter) Mass flow rate of ceramic particles in the aerosol ejected from the nozzle: 0.5 g / s (measured with a flow meter) Inner diameter of the aerosol generator nozzle: 12 mm -Operating conditions Suction flow rate of the blower: 4000 l / min Average flow velocity of the aerosol flowing in the chamber: 1 m / s (measured with Anemomaster) Average flow velocity of the aerosol flowing in the columnar honeycomb structure: approx. 7 m / s (calculated from flow rate / cell opening area) End point of the step to attach the ceramic particles: when the differential pressure reading reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies because the film mass is adjusted depending on the product volume). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0144] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0145] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0146] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0147] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <Beispiel 4> (1) Production of a columnar honeycomb structure

[0148] A columnar honeycomb structure was obtained under the same manufacturing conditions as in Example 1, except that the overall shape was changed to an elliptical cylindrical shape with a major axis of 235 mm, a minor axis of 146 mm and a height of 120 mm. (2) Attaching ceramic particles to a columnar honeycomb structure

[0149] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig.In the configuration shown in 5A, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, causing the ceramic particles to adhere to the surface of the first cells. The specifications and operating conditions of the particle attachment device were the same as in Example 3, except that the chamber length was set to 1600 mm. Since the cell opening area of ​​the columnar honeycomb structure in Example 4 differed from that in Example 3, the average flow velocity of the aerosol flowing in the columnar honeycomb structure was approximately 5 m / s (calculated by flow rate / cell opening area). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0150] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0151] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0152] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0153] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <Beispiel 5> (1) Production of a columnar honeycomb structure

[0154] Under the same manufacturing conditions as in Example 3, a columnar honeycomb structure was obtained. (2) Attaching ceramic particles to a columnar honeycomb structure

[0155] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig. In the configuration shown in Figure 5A, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows.

[0156] The specifications and operating conditions of the particle application device were the same as in Example 3, except that a disc-shaped plate with a diameter of 150 mm and an insertion port for the nozzle of the aerosol generator, with the insertion port in the center, was fixed on the surface opposite the inlet-side end face of the columnar honeycomb structure. The disc-shaped plate covered 20% of the area of ​​the opposite surface (inner surface). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0157] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0158] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles adhering to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200°C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure ranged from 2 g / L to 10 g / L relative to the product volume. Furthermore, a sufficient number of columnar honeycomb filters were produced to perform the subsequent property evaluation. (5) Porosity and average pore diameter

[0159] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0160] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <Beispiel 6> (1) Production of a columnar honeycomb structure

[0161] Under the same manufacturing conditions as in Example 3, a columnar honeycomb structure was obtained. (2) Attaching ceramic particles to a columnar honeycomb structure

[0162] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig. In the configuration shown in Figure 5A, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows. -Chamber Shape: cylindrical Inner diameter: 300 mm Length: 600 mm Ambient gas: Air Opening position for the introduction of ambient gas: only on the surface opposite the inlet-side end face of the columnar honeycomb structure. Structure of the opposite surface: punched plate Filter installation in the openings: Yes Position of the aerosol generator nozzle: center of the opposite surface Distance L from the nozzle outlet of the aerosol generator to the inlet-side end face of the columnar honeycomb structure: 600 mm -Aerosol generator Product name: none, manufactured in-house (with the in Fig. (Structure shown in 4B) Type: Continuous-type aerosol generator Connection method of the drive gas flow path and the flow path for intake and transport: Venturi ejector Location where the feed port for ceramic particles was installed: on the downstream side of the narrowest point of the Venturi section and adjacent to this point Type of feed of ceramic particles into the receiving unit: screw conveyor Type of intake unit: Funnel Type of ceramic particles captured in the capture unit: SiC particles Volume-related particle diameter distribution of the ceramic particles captured in the capture unit (measured using laser diffraction / laser scattering methods): Median diameter (D50) = 3 µm, SiC particles with a particle diameter of 10 µm or more: ≤ 20 vol.% Propellant gas: compressed dry air (dew point 10 °C or less) Ambient gas drawn in: Air Average flow rate of the ambient gas through the drive gas flow path: 40 l / min (measured with a flow meter) Average flow rate of the propellant gas before it meets the aspirated ambient gas: 80 l / min Flow velocity of the propellant gas immediately before the propellant gas flows through the Venturi section: 26 m / s (measured with Anemomaster) Ratio of the flow path cross-sectional area immediately before the Venturi section to the flow path cross-sectional area of ​​the Venturi section = 1:0.028 Average flow velocity of the aerosol ejected from the nozzle: 26 m / s (measured with an Anemomaster at a position 10 to 20 mm downstream of the nozzle) Average flow rate of the aerosol ejected from the nozzle: 120 l / min (measured with a flow meter) Mass flow rate of ceramic particles in the aerosol ejected from the nozzle: 0.5 g / s (measured with a flow meter) Inner diameter of the aerosol generator nozzle: 12 mm -Laser diffraction-type measuring device for particle diameter distribution. Product name: Insitec Spray, manufactured by Malvern -Operating conditions Suction flow rate of the blower: 4000 l / min Average flow velocity of the aerosol flowing in the chamber: 1 m / s (measured with Anemomaster) Average flow velocity of the aerosol flowing in the columnar honeycomb structure: approx. 7 m / s (calculated from flow rate / cell opening area) End point of the step to attach the ceramic particles: when the differential pressure reading reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies because the film mass is adjusted depending on the product volume). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0163] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0164] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0165] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0166] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <Vergleichsbeispiel 1> (1) Production of a columnar honeycomb structure

[0167] Under the same manufacturing conditions as in Example 1, a columnar honeycomb structure was obtained. (2) Attaching ceramic particles to a columnar honeycomb structure

[0168] The columnar honeycomb structure produced above was then treated using the particle attachment device with the [unclear text] Fig. In the configuration shown in Figure 5B, an aerosol containing ceramic particles was ejected from a direction perpendicular to the inlet-side end face towards the center of the inlet-side end face of the columnar honeycomb structure, so that the ceramic particles adhered to the surface of the first cells. The specifications and operating conditions of the particle attachment device were as follows. -Chamber Shape: cylindrical Inner diameter: 300 mm Length: 600 mm Ambient gas: Air Opening position for the introduction of ambient gas: only on the surface opposite the inlet-side end face of the columnar honeycomb structure. Structure of the opposite surface: punched plate Filter installation in the openings: Yes Position of the aerosol generator nozzle: center of the opposite surface Distance L from the nozzle outlet of the aerosol generator to the inlet-side end face of the columnar honeycomb structure: 600 mm -Aerosol generator Product name: Model VRL50-080608, manufactured by PISCO (with the in Fig. (4D shown structure) Type: Continuous-type aerosol generator Connection method of the drive gas flow path and the flow path for suction and transport: Coanda-type ejector Type of feed of ceramic particles into the receiving unit: screw conveyor Type of intake unit: Funnel Type of ceramic particles captured in the capture unit: SiC particles Volume-related particle diameter distribution of the ceramic particles captured in the recording unit (measured using laser diffraction / laser scattering methods): Median diameter (D50) = 50 µm (aggregation of 100 µm or more is common) Propellant gas: compressed dry air (dew point 10 °C or less) Ambient gas drawn in: Air Average flow rate of the ambient gas through the intake and transport pipe: 4000 l / min (measured with a flow meter) Average flow rate of the propellant gas before it meets the aspirated ambient gas: 35 l / min Flow velocity of the propellant gas immediately before the propellant gas flows through the Venturi section: 20 m / s (measured with Anemomaster) Average flow velocity of the aerosol ejected from the nozzle: 26 m / s (measured with an Anemomaster at a position 10 to 20 mm downstream of the nozzle) Average flow rate of the aerosol ejected from the nozzle: 35 l / min (measured with a flow meter) Mass flow rate of ceramic particles in the aerosol ejected from the nozzle: 0.1 g / s (measured with a flow meter) Inner diameter of the aerosol generator nozzle: 8 mm -Laser diffraction-type measuring device for particle diameter distribution. Product name: Insitec Spray, manufactured by Malvern -Operating conditions Suction flow rate of the blower: 4000 l / min Average flow velocity of the aerosol flowing in the chamber: 1 m / s (measured with Anemomaster) Average flow velocity of the aerosol flowing in the columnar honeycomb structure: approx. 10 m / s (calculated from flow rate / cell opening area) End point of the step to attach the ceramic particles: when the differential pressure reading reaches +0.1 kPa to +0.4 kPa (the differential pressure value varies because the film mass is adjusted depending on the product volume). (3) Measurement of the particle diameter distribution of ceramic particles in aerosol

[0169] While the particle attachment device was in operation, a laser diffraction-type particle diameter distribution measuring device measured the volume-based particle diameter distribution of the ceramic particles in the aerosol emitted from the aerosol generator. The median diameter (D50) and the proportion of ceramic particles with a particle diameter of 10 µm or more were determined. The results are shown in Table 1. (4) Formation of porous films

[0170] Regarding the resulting columnar honeycomb structure to which the ceramic particles were attached, the ceramic particles attached to the inlet-side end face were suctioned off and removed by vacuum, while the inlet-side end face was leveled with a scraper. The columnar honeycomb structure was then placed in an electric furnace and heat-treated in an air atmosphere, being held at a maximum temperature of 1200 °C for 2 hours to form porous films on the surface of the first cells, thus obtaining a columnar honeycomb filter. From the mass change before and after the application of the ceramic particles, it was confirmed that the mass of the porous films formed on the columnar honeycomb structure was 2 to 10 g / l relative to the product volume. Furthermore, a necessary number of columnar honeycomb filters were produced to carry out the subsequent property evaluation. (5) Porosity and average pore diameter

[0171] The porosity and average pore diameter of the porous films and partitions of the columnar honeycomb filter obtained by the above manufacturing process were measured using the same method as in Example 1. The results are shown in Table 1. (6) Quality stability

[0172] For ten columnar honeycomb filters obtained by the above manufacturing process, the coefficient of variation of the porous film thickness was determined in the same way as in Example 1. The results are shown in Table 1. <diskussion>

[0173] In comparative example 1, where the aerosol generator structure was unsuitable, the ceramic particles in the aerosol were coarse. Conversely, in examples 1 to 6, where the aerosol generator structure was suitable, the ceramic particles in the aerosol were fine. This is because the aerosol generators in examples 1 to 6 were able to suppress the aggregation of ceramic particles.

[0174] Furthermore, in Examples 1, 3 to 6 of the device for attaching particles, the quality stability was improved compared to Example 2, in which the openings for admitting the ambient gas were provided on the side wall, since the openings for admitting the ambient gas were provided in such a way that they faced the inlet-side end face. Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 1. Device configuration Aerosol generator Fig. 4A Fig. 4C Fig. 4C Fig. 4C Fig. 4C Fig. 4B Fig. 4D Device for attaching particles Fig. 5A Fig. 5B Fig. 5A Fig. 5A Fig. 5C Fig. 5A Fig. 5A 2. Ceramic particles in aerosol Material of ceramic particles silicon carbide silicon carbide silicon carbide silicon carbide silicon carbide silicon carbide silicon dioxide Median diameter (D50) (µm) 3,1 3,2 3,2 3,2 3,0 3,0 50,0 Volume fraction (%) of particles of 10 µm or larger 10 10 10 10 10 10 70 3. Properties of the columnar honeycomb structure filter <Trennwände> Porosity (%) 55,0 55,0 55,0 55,0 55,0 55,0 55,0 Average pore diameter (µm) 8,8 8,8 8,8 8,8 8,8 8,8 8,8 (Porous films> Porosity (%) 70 70 70 70 70 70 70 Average pore diameter (µm) 3,5 3,5 3,5 3,5 3,5 3,5 3 to 5 4. Quality stability 0,24 0,38 0,29 0,29 0,29 0,27 0,27 Reference symbol list 100 Columnar honeycomb structure filters 102 Outer perimeter side wall 104 Inlet-side front surface 106 Outlet-side front surface 108 First cell 109 Blocked section 110 Second cell 112 Partition wall 114 Porous film 410 Aerosol generator 411 Nozzle 412 ceramic particles 413 cylinders 413e Cylinder exhaust 414 Piston or screw 415 Loosening chamber 415i Inlet 415e outlet 416 Rotating bodies 417 Drive gas flow path 417i Supply connection 420 Aerosol generator 421 Nozzle 422 ceramic particles 423 Flow path 423e Outlet 427 Drive gas flow path 427i Supply connection 427v Venturi section 429 recording unit 429i Inlet 429e Outlet 4210 Venturi ejector 4211 Powder dosing conveyor 430 Aerosol generator 431 Nozzle 432 ceramic particles 433 Flow path 433i Inlet 433e Outlet 434 belt conveyors 435 Loosening chamber 435in entrance 435e outlet 436 Rotating Bodies 437 Drive gas flow path 437i Supply connection 437v Venturi section 438 stirrers 439 Recording unit 439e Delivery point 4310 Venturi ejector 500 Columnar honeycomb structure 502 Outer perimeter side wall 504 Inlet-side end face 506 Outlet-side front surface 510 Device for attaching particles 511 Aerosol generator 511a nozzle 512 blowers 513 Chamber 513a Surface opposite the inlet-side end face 513b Insertion port 513c opening 513d side panel 513e Downstream end 513f Upstream end 513g filters 513h Reduced Section 514 holders 514a Housing 514b Clamping mechanism 514e Outlet connection 515 Outlet pipe 516 Flow meter 518 Closure section 519 Laser diffraction type measuring device for particle diameter distribution 520 Device for attaching particles 530 Device for attaching particles 550 Differential pressure gauge 610 Aerosol generator 614 Nozzle 614a Diffuser section 614b Narrowing section 614 in entrance 614e Ejection port 615 pipe 615e outlet 616 Gas flow path 616e outlet 617 Interior wall area 617a Cylindrical section 617b Tapered Section 618 Inlet pipe 619 External perimeter area 619a Cylindrical section 619b Section with increased diameter 619c Tapered Section 622 ceramic particles 629 recording unit 629i Inlet 629e Outlet< / diskussion>

Claims

[1] Method for producing a columnar honeycomb structure filter (100, 500) comprising: a step of producing a columnar honeycomb structure comprising: several first cells (108) extending from an inlet-side end face (104, 504) to an outlet-side end face (106, 506), each opening at the inlet-side end face (104, 504) and having a closed section (109) at the outlet-side end face (106, 506), and several second cells (110) extending from the inlet-side end face (104, 504) to the outlet-side end face (106, 506), each having a closed section (109) at the inlet-side end face (104, 504) and opening at the outlet-side end face (106, 506), the several first cells (108) and the several second cells (110) being alternately adjacent to each other with a porous partition (112) between them, and a step of attaching ceramic particles (412, 422, 432) to a surface of the first cells (108) by ejecting an aerosol containing the ceramic particles (412, 422, 432) in the direction of the inlet-side end face (104, 504) from a direction perpendicular to the inlet-side end face (104, 504), while a suction force is exerted on the outlet-side end face (106, 506) to draw the ejected aerosol away from the inlet-side end face (104, 504); wherein the emission of the aerosol is carried out using an aerosol generator (410, 420, 430, 511, 610) which has a drive gas flow path (417, 427, 437) for guiding a pressurized drive gas, a feed port (417i, 427i, 437i) provided on the drive gas flow path (417, 427, 437) which can draw the ceramic particles (412, 422, 432) from an outer circumferential side of the drive gas flow path (417, 427, 437) to an inner side of the drive gas flow path (417, 427, 437), and a nozzle (411, 421, 431, 511q) located at a tip of the drive gas flow path (417, 427, 437) is attached and can emit the aerosol, includes, where The aerosol (411, 421, 431, 511a) ejected from the nozzle flows through a chamber (513) provided between the nozzle (411, 421, 431, 511a) and the inlet-side end face (104, 504) and is drawn in by the inlet-side end face (104, 504). the chamber (513) has a surface (513a) opposite the inlet-side end face (104, 504), the opposite surface (513a) has an insertion port for the nozzle (411, 421, 431, 511a) and one or more openings (513c) for letting ambient gas into the chamber (513), and the chamber (513) has no openings for letting in ambient gas other than those on the opposite surface (513a). [2] Method according to claim 1, wherein the ceramic particles (412, 422, 432) in the aerosol have a median diameter (D50) of 1.0 to 6.0 µm in a volume-based cumulative particle diameter distribution measured by a laser diffraction / laser scattering method. [3] Method according to claim 1 or 2, wherein, for the ceramic particles (412, 422, 432) in the aerosol, in a volume-based particle diameter frequency distribution measured by laser diffraction / laser scattering methods, the ceramic particles of 10 µm or more constitute 20 vol.-% or less. [4] Method according to any one of claims 1 to 3, wherein the opposite surface (513a) of the chamber (513) has a concentric closure section (518) centered on the insertion port, and one or more openings (518) are provided on an outer circumferential side of the closure section. [5] Method according to any one of claims 1 to 4, wherein the average flow velocity of the aerosol in the chamber (513) during the step of applying ceramic particles (412, 422, 432) to the surface of the first cells is 0.5 m / s to 3.0 m / s. [6] Method according to any one of claims 1 to 5, wherein the aerosol generator further comprises: a cylinder (413) for receiving the ceramic particles (412), a piston (414) or a screw for ejecting the ceramic particles (412) received in the cylinder (413) from a cylinder outlet (413e), and a loosening chamber (415) comprising an inlet (415i) connected to the cylinder outlet (415e), a rotating body (416) for loosening the ceramic particles (412) discharged from the cylinder outlet (413e) and an outlet connected to the feed port (417i). [7] Method according to any one of claims 1 to 5, wherein the aerosol generator further comprises: a flow path (423) for drawing in and transporting the ceramic particles (422), which includes an outlet (423e) that is connected to the feed port (427i), and a receiving unit (429) for receiving the ceramic particles (422) and for supplying the ceramic particles (422) to the flow path (423) for suction and transport; wherein the propulsion gas flow path (427) includes a Venturi section (427v) in which the flow path is narrowed, and the supply port (427i) is provided on the downstream side of the narrowest flow path point in the Venturi section (427v). [8] Method according to any one of claims 1 to 5, wherein the aerosol generator further comprises: a flow path (433) for drawing in and transporting the ceramic particles (432), which includes an outlet (433e) that is connected to the feed port (437i), a belt conveyor (434) for transporting the ceramic particles (432) and a loosening chamber (435) comprising an inlet (435in) for receiving the ceramic particles (432) transported by the belt conveyor (435), a rotating body (436) for loosening the received ceramic particles (432) and an outlet connected to the flow path for suction and transport. [9] Method according to any one of claims 1 to 8, wherein an endpoint of the step of applying the ceramic particles (412, 422, 432) to the surface of the first cells (108) is determined based on a value of a differential pressure gauge installed to measure the pressure loss between the inlet-side end face (104, 504) and the outlet-side end face (106, 506) of the columnar honeycomb structure. [10] Method according to any one of claims 1 to 8, wherein in the step of applying the ceramic particles (412, 422, 432) to the surface of the first cells (108) the average flow velocity of the aerosol flowing within the columnar honeycomb structure is 5 m / s or more. [11] Method according to any one of claims 1 to 10, wherein a major component of the ceramic particles (412, 422, 432) is silicon carbide, aluminium oxide, silicon dioxide, cordierite or mullite. [12] Device for attaching particles for a columnar honeycomb structure, comprising: a holder (514) for holding the columnar honeycomb structure, comprising: several first cells (108) extending from an inlet-side end face (104, 504) to an outlet-side end face (106, 506), each opening at the inlet-side end face (104, 504) and having a closed section (109) at the outlet-side end face (106, 506), and several second cells (110) extending from the inlet-side end face (104, 504) to the outlet-side end face (106, 506), each having a closed section at the inlet-side end face (104, 504) and opening at the outlet-side end face (106, 506), the several first cells (108) and the several second cells (110) being alternately adjacent to each other with are arranged between a porous partition (112), a blower (512) for applying a suction force to the outlet-side end face (106, 506) of the columnar honeycomb structure, and an aerosol generator (410, 420, 430, 511, 610) for emitting an aerosol containing ceramic particles in the direction of the inlet-side end face (104, 504) from a direction perpendicular to the inlet-side end face (104, 504) and attaching the ceramic particles (412, 422, 432) to a surface of the first cells (108); and a chamber (513) provided between the nozzle (411, 421, 431, 511q) and the inlet-side face (104, 504) to guide the aerosol through its interior wherein the aerosol generator (410, 420, 430, 511, 610) comprises: a propulsion gas flow path (417, 427, 437) for guiding a pressurized propulsion gas, a feed port (417i, 427i, 437i) provided along the path of the propulsion gas flow path (417, 427, 437) which can draw the ceramic particles (412, 422, 432) from an outer circumferential side of the propulsion gas flow path (417, 427, 437) towards an inner side of the propulsion gas flow path (417, 427, 437), and a nozzle (411, 421, 432, 511q) attached at a tip of the propulsion gas flow path (417, 427, 437) and which can emit aerosol the chamber (513) has a surface (513a) opposite the inlet-side end face (104, 504), the opposite surface (513a) has an insertion port for the nozzle (411, 421, 431, 511q) and one or more openings (513c) for letting ambient gas into the chamber (513), and the chamber (513) has no openings for letting in ambient gas other than those on the opposite surface (513a). [13] Device for attaching particles for a columnar honeycomb structure according to claim 12, wherein the opposite surface (513a) has a concentric closure section (518) centered on the insertion port, and one or more openings (513a) are provided on an outer circumferential side of the closure section (518). [14] Device for attaching particles for a columnar honeycomb structure according to one of claims 12 or 13, wherein the aerosol generator (410) further comprises: a cylinder (413) for receiving the ceramic particles (412), a piston (414) or a screw for ejecting the ceramic particles (412) received in the cylinder (413) from a cylinder outlet (413e), and a loosening chamber (415) which has an inlet (415i) connected to the cylinder outlet (413e), a rotating body (416) for loosening the ceramic particles (412) discharged from the cylinder outlet (413e) and an outlet (415e) connected to the feed port (417i). [15] Device for attaching particles for a columnar honeycomb structure according to one of claims 12 or 13, wherein the aerosol generator (420) further comprises: a flow path z(423) for drawing in and transporting the ceramic particles (422), which has an outlet (423e) that is connected to the supply port (427i), and a receiving unit (429) for receiving the ceramic particles (422) and for supplying the ceramic particles (422) to the flow path (424) for suction and transport; wherein the propulsion gas flow path (427) has a Venturi section (427v) along its path in which the flow path (427i) is narrowed, and the supply port is provided on the downstream side of the narrowest flow path point in the Venturi section (427v). [16] Device for attaching particles for a columnar honeycomb structure according to one of claims 12 or 13, wherein the aerosol generator (430) further comprises: a flow path (433) for drawing in and transporting the ceramic particles (432), which has an outlet (433e) that is connected to the supply port (437i), a belt conveyor (434) for transporting the ceramic particles (432) and a loosening chamber (435) which has an inlet (433i) for receiving the ceramic particles (432) transported by the belt conveyor (434), a rotating body (436) for loosening the received ceramic particles (432) and an outlet (435e) connected to the flow path (433) for suction and transport.

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