Honeycomb filter

Abstract

The utility model provides a honeycomb filter which is excellent in trapping performance. A honeycomb filter is characterized by being provided with: a columnar honeycomb structure section having porous partition walls arranged so as to surround a plurality of cells that serve as flow paths for a fluid extending from a first end surface to a second end surface; and a sealing part that is disposed at the opening of each of the cells on the first end surface side or the second end surface side, and in the pore diameter distribution of the partition walls obtained by structural analysis, D90 is the pore diameter at which the cumulative pore volume is 90% of the total pore volume, and D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter at which D90 is the pore diameter. In the porous structure of the partition wall as determined by structural analysis, the product of the D90 and the average neck diameter is 1.0 * 10-10 m2 or more and 9.0 * 10-10 m2 or less, where the average neck diameter is the average equivalent circle diameter of the neck at which the flow path area of the communicating pores in the porous structure is minimum. Wherein the unit of the pore diameter, D90, the average value and the average neck diameter is m.

Description

Technical Field

[0001] This utility model relates to a honeycomb filter. More specifically, it relates to a honeycomb filter with excellent capture performance. Background Technology

[0002] Conventionally, honeycomb filters (see Patent Documents 1-5) have been known as devices for capturing particulate matter in exhaust gases from internal combustion engines such as automobile engines and for purifying toxic gases such as CO, HC, and NOx. These honeycomb structures have partitions made of porous ceramics such as cordierite, which divide the exhaust gases into multiple compartments. In contrast to the aforementioned honeycomb structure, the honeycomb filter is configured with alternating sealing portions on the inflow and outflow sides of the multiple compartments. That is, the honeycomb filter has an inflow compartment with an open inflow side and a sealed outflow side, and an outflow compartment with a sealed inflow side and an open outflow side, separated by partitions. Furthermore, in the honeycomb filter, the porous partitions function as a filter to capture particulate matter in the exhaust gases. Hereinafter, particulate matter contained in the exhaust gases will sometimes be referred to as "PM." "PM" is an abbreviation for "particulate matter."

[0003] The purification of exhaust gas using a honeycomb filter is as follows. First, the honeycomb filter is configured such that its inlet end face is upstream of the exhaust system from which the exhaust gas is discharged. Exhaust gas flows into the inlet compartment from the inlet end face of the honeycomb filter. Then, the exhaust gas flowing into the inlet compartment passes through a porous partition wall to the outlet compartment and is discharged from the outlet end face of the honeycomb filter. During passage through the porous partition wall, particulate matter (PM) and other contaminants in the exhaust gas are captured and removed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5507575

[0007] Patent Document 2: Japanese Patent No. 5469335

[0008] Patent Document 3: Japanese Patent No. 5518327

[0009] Patent Document 4: Japanese Patent No. 5372494

[0010] Patent Document 5: Japanese Patent No. 6004150 Utility Model Content

[0011] The problem to be solved by the utility model

[0012] Honeycomb filters used to purify exhaust gases from automobile engines employ highly porous materials as porous partitions. In recent years, due to stricter regulations on automobile exhaust emissions, there is a need to further improve the collection performance of honeycomb filters.

[0013] In the past, in order to improve the collection performance of honeycomb filters, for example, the average pore size and pore size distribution of the porous septum have been controlled. For example, as a method to control the pore size distribution, attempts have been made to adjust the average pore size or to adjust the value of the pore size D90, which is 90% of the total pore volume, thereby improving the collection performance of the honeycomb filter.

[0014] PM such as soot in exhaust gases is captured by the pores of the porous partitions that make up a honeycomb filter. However, the neck portion of the pores in the partitions, where the flow path area narrows, can sometimes affect the capture performance. Previously, the average pore size and pore size distribution of the partitions were measured using the mercury method, such as a mercury porosimeter. However, in conventional measurements using mercury porosimeters, information about the diameter of the neck portion (hereinafter also referred to as "neck diameter") within the pores of the partitions cannot be obtained. Therefore, simply controlling parameters such as the average pore size and pore size distribution specified in existing technologies may not achieve a sufficient improvement in capture performance. There is a need to develop new technologies to improve the capture performance of honeycomb filters.

[0015] This invention was made in view of the problems existing in the prior art. According to this invention, a honeycomb filter with excellent trapping performance is provided.

[0016] Solution for solving the problem

[0017] According to this utility model, a honeycomb filter as shown below is provided.

[0018] [1] A honeycomb filter, characterized in that it comprises: a columnar honeycomb structure having porous partitions arranged to surround a plurality of compartments, the plurality of compartments forming a flow path for fluid extending from a first end face to a second end face; and a sealing portion having an opening disposed on the first end face side or the second end face side of each of the compartments, wherein in the pore size distribution of the partitions determined by structural analysis, the pore size that accumulates to 90% of the total pore volume is defined as D90; in the porous structure of the partitions determined by the structural analysis, the average value of the equivalent circle diameter of the neck that minimizes the flow path area of ​​the communicating pores in the porous structure is defined as the average neck diameter; and the product of D90 and the average neck diameter is 1.0 × 10⁻⁶. -10 m 2 Above and 9.0×10 -10 m 2In the following, the units for fine pore diameter, D90, average value, and average neck diameter are in meters (m).

[0019] [2] The cellular filter according to [1] above is characterized in that the D90 is 1.0 × 10⁻⁶. -5 m or more and 8.0 × 10 -5 Below m.

[0020] [3] The honeycomb filter according to [1] or [2] above is characterized in that the average neck diameter is 5.0 × 10⁻⁶. -6 m or more and 1.7 × 10 -5 Below m.

[0021] [4] According to the honeycomb filter described in [1] or [2] above, the characteristic is that, in the pore size distribution of the partition wall obtained by the structural analysis, the pore size that accumulates to 10% of the total pore volume is set as D10, where D10 is 5.0 × 10⁻⁶. -6 m or more and 2.5 × 10 -5 Below m, where D10 is in meters.

[0022] [5] According to the honeycomb filter described in [1] or [2] above, the characteristic is that, in the pore size distribution of the partition wall obtained by the structural analysis, the pore size that accumulates to 50% of the total pore volume is set as D50, and D50 is 1.7 × 10⁻⁶. -5 m or more and 4.1 × 10 -5 Below m, where D50 is in meters.

[0023] [6] The honeycomb filter according to [1] or [2] above is characterized in that the percentage of porosity of the partition wall determined by the structural analysis is more than 33% and less than 65%.

[0024] Utility Model Effect

[0025] This invention relates to a honeycomb filter that achieves excellent trapping performance. Specifically, the honeycomb filter combines the D90 value of the pore size distribution of the partition walls, obtained through structural analysis, with the average neck diameter of the porous structure of the partition walls. Based on parameters highly correlated with trapping performance, it achieves a porous structure extremely suitable for trapping performance. The neck diameter of the porous structure of the partition walls is an effective parameter for improving trapping performance. In this invention, a structural analysis-based method is used to directly measure such a neck diameter. Attached Figure Description

[0026] Figure 1This is a perspective view schematically illustrating one embodiment of the honeycomb filter of the present invention, as seen from the inflow end face.

[0027] Figure 2 From Figure 1 A top view of the inflow end face of the shown cellular filter.

[0028] Figure 3 It is a schematic representation Figure 2 A sectional view of section A-A'.

[0029] Figure 4 This is an example of a grayscale image used to determine the pore size distribution of the partition wall. Detailed Implementation

[0030] The following describes the embodiments of this utility model, but this utility model is not limited to the following embodiments. Therefore, it should be understood that appropriate changes or improvements made to the following embodiments based on common knowledge of those skilled in the art, without departing from the spirit of this utility model, also fall within the scope of this utility model.

[0031] (1) Honeycomb filter:

[0032] like Figures 1-3 As shown, the first embodiment of the honeycomb filter of this utility model is a honeycomb filter 100 having a honeycomb structure portion 4 and a sealing portion 5. The honeycomb structure portion 4 is a columnar honeycomb structure portion having porous partitions 1, which are arranged to surround a plurality of compartments 2 that form a flow path for fluid extending from a first end face 11 to a second end face 12. In the honeycomb filter 100, the honeycomb structure portion 4 is columnar, and its outer peripheral side also has an outer peripheral wall 3. That is, the outer peripheral wall 3 is arranged to surround the partitions 1 arranged in a grid pattern.

[0033] The sealing portion 5 is provided at the opening on the first end face 11 or the second end face 12 of each compartment 2. Figures 1-3 In the shown honeycomb filter 100, sealing portions 5 are respectively provided at the openings on the first end face 11 side of the predetermined compartment 2 and at the openings on the second end face 12 side of the remaining compartment 2. Here, when the first end face 11 is designated as the inflow end face and the second end face 12 as the outflow end face, the compartment 2 with the sealing portion 5 provided at the opening on the outflow end face side and the opening on the inflow end face side is designated as the inflow compartment 2a. In addition, the compartment 2 with the sealing portion 5 provided at the opening on the inflow end face side and the opening on the outflow end face side is designated as the outflow compartment 2b. Preferably, the inflow compartment 2a and the outflow compartment 2b are alternately arranged with the partition wall 1 in between. Moreover, it is preferable that a grid pattern is formed on both ends of the honeycomb filter 100 using the sealing portions 5 and the "openings of the compartment 2".

[0034] Figure 1 This is a perspective view schematically illustrating one embodiment of the honeycomb filter of the present invention, as seen from the inflow end face. Figure 2 From Figure 1 A top view of the inflow end face of the shown cellular filter. Figure 3 It is a schematic representation Figure 2 A sectional view of section A-A'.

[0035] The honeycomb filter 100 has a characteristic structure regarding the porous structure of the partitions 1 constituting the honeycomb structure 4. Here, in the pore size distribution of the partitions 1 obtained through structural analysis of the honeycomb filter 100, the pore size (m) that accumulates to 90% of the total pore volume is defined as D90 (m). Furthermore, in the porous structure of the partitions 1 obtained through the above structural analysis, the average value (m) of the equivalent circle diameter of the neck that minimizes the flow path area of ​​the communicating pores in the porous structure is defined as the average neck diameter (m). The honeycomb filter 100 is mainly configured such that the product of D90 (m) and the average neck diameter (m) is 1.0 × 10⁻⁶. -10 m 2 Above and 9.0×10 -10 m 2 In this specification, unless otherwise specified, "pore size distribution of partition 1" refers to the pore size distribution of partition 1 obtained through structural analysis of the honeycomb filter 100 described above. Similarly, unless otherwise specified, "porous structure of partition 1" refers to the porous structure of partition 1 obtained through structural analysis of the honeycomb filter 100 described above. Furthermore, the equivalent circle diameter of the neck, which minimizes the flow path area of ​​the connecting pores in the porous structure of partition 1, is sometimes referred to as the "neck diameter (m)". In this specification, the fine pores in the porous structure are referred to as "pores" or "air pores", and in particular, the pores (air pores) that connect two adjacent compartments 2, 2 separated by partition 1 are referred to as "connecting air pores".

[0036] The honeycomb filter 100 is a honeycomb filter that achieves excellent collection performance. Specifically, the honeycomb filter 100 combines the value of D90(m) in the pore size distribution of the partition wall 1 with the value of the average neck diameter (m) in the porous structure of the partition wall 1, achieving a porous structure highly suitable for collection performance based on parameters highly correlated with collection performance. The neck diameter (m) of the porous structure of the partition wall 1 is an effective parameter for improving collection performance. In the honeycomb filter 100 of this embodiment, a method based on specific structure analysis is used to directly measure such a neck diameter. Furthermore, in the honeycomb filter 100 of this embodiment, as described above, the product of D90(m) and the average neck diameter (m) is used as a parameter highly correlated with collection performance. For example, particulate matter (PM) contained in exhaust gases is not entirely collected by the neck; therefore, the narrower the space after the neck, the easier it is to collect PM. Therefore, a high correlation between the average neck diameter and collection performance is not found solely through the value of the average neck diameter.

[0037] If the product of the above D90 (m) and the average neck diameter (m) is less than 1.0 × 10 -10 m 2 If the pressure drop performance deteriorates and the catalyst is prone to clogging at the neck, it is not preferred. On the other hand, if the product of D90 (m) and the average neck diameter (m) exceeds 9.0 × 10⁻⁶, it is also undesirable. -10 m 2 If this happens, the trapping performance deteriorates. The product of D90 (m) and the average neck diameter (m) only needs to be 1.0 × 10⁻⁶. -10 m 2 Above and 9.0×10 -10 m 2 The following is acceptable, for example, 3.0 × 10 is preferred. -10 m 2 Above and 7.0×10 -10 m 2 the following.

[0038] The value of D90(m) is not particularly limited, but is preferably 1.0 × 10⁻⁶. -5 m or more and 8.0 × 10 -5 Below m, more preferably 3.0 × 10 m. -5 m or more and 7.0 × 10 -5 Below m. With this configuration, the collection performance of the honeycomb filter 100 can be further improved. For example, by setting the D90(m) in the pore size distribution to a lower value and reducing the number of large pores, it is possible to suppress the local increase in the flow velocity of the fluid passing through the partition wall 1, thereby significantly improving the collection efficiency of the honeycomb filter 100.

[0039] Furthermore, the average neck diameter (m) of the porous structure of partition 1 is not particularly limited, but is preferably 5.0 × 10⁻⁶.-6 m or more and 1.7 × 10 -5 For m or less, 1.0 × 10 is more preferred. -5 m or more and 1.6 × 10 -5 Below m. This configuration further improves the collection performance of the cellular filter 100. It should be noted that if the average neck diameter (m) is also smaller than D90 (m), the improvement in collection performance is effective.

[0040] In this invention, "the pore size distribution of the partition 1 obtained through structural analysis" refers to the pore size distribution obtained through structural analysis based on the following analytical method. Specifically, it refers to the pore size distribution obtained by using the "Identify Pores function," one of the interface modules of "GeoDict" (trade name, hereinafter the same)), a microstructure simulation software developed by Math2Market GmbH of Germany. Hereinafter, "the analytical method using the Identify Pores function" is sometimes referred to as the "Identify Pores analytical method." Therefore, the "pore size distribution of the partition 1" of the honeycomb filter 100 of this embodiment refers to the pore size distribution of the partition 1 obtained by the Identify Pores analytical method. The pore size distribution of the partition 1 obtained by the Identify Pores analytical method can more accurately analyze the pore size inside the partition 1. That is, even in the case where there are parts of the pores that expand in diameter and parts that contract in diameter (i.e., necks) inside the partition wall 1, their pore diameters can be properly determined. Therefore, the pore diameters inside the partition wall 1, especially those inside the neck of the pores, which are difficult to accurately measure in the conventional mercury osmosis method, can be obtained more accurately.

[0041] Here, the "Identify Pores analytical method" used to determine the pore size distribution of the partition 1 will be explained. Hereinafter, the "Identify Pores analytical method" will sometimes be referred to simply as "this analytical method". In this analytical method, for the partition 1 of the cellular filter 100, tomographic images are obtained using an X-ray CT device, and the pore size distribution of the partition 1 is determined from the partition structure model formed by three-dimensionalizing the obtained tomographic images.

[0042] Specifically, firstly, a portion of the partition wall 1 is cut from the honeycomb filter 100 to prepare a partition wall sample for analysis. However, the portion containing the sealing pores 5 is removed from the partition wall sample. It should be noted that the partition wall sample is collected at the central position in both the direction extending from the first end face 11 to the second end face 12 of the honeycomb filter 100 (hereinafter also referred to as "axial X") and in the direction orthogonal to the axial X. The partition wall sample is formed as a cuboid with a length of approximately 1 cm in the axial X direction, a width of approximately 0.5 cm in the direction of the surface of the partition wall 1 orthogonal to the axial X direction, and a thickness equal to the thickness of the partition wall 1 in both the length and width directions.

[0043] Next, the prepared septum sample is used as an X-ray CT imaging sample. Here, "CT" is short for Computed Tomography. For this sample, continuous tomographic images are obtained using an X-ray CT apparatus under the following imaging conditions: voltage: 60kV, lens: 4x, filter: LE1, resolution: 1.2μm / pixel. For example, the Zeiss Xradia520 Versa (trade name) can be used as the X-ray CT apparatus. There are no particular restrictions on the image file format of the continuous tomographic images, as long as it is an image file format that can be used in this analytical method. For example, the obtained continuous tomographic images can be in TIFF (Tagged Image File Format) format or BMP (Bitmap) format. An example of obtaining TIFF format continuous tomographic images will be described below. The obtained TIFF continuous tomographic images were read using the "ImportGeo function," a module of "GeoDict," a microstructure simulation software developed by Math2Market GmbH, at a resolution of 1.2 μm / voxel.

[0044] Next, in order to separate the skeleton and spatial parts of the read image, Figure 4 The intersection of the two peaks in the grayscale image is used as the threshold to model the partition wall sample in three dimensions.

[0045] Next, noise from the 3D model is removed by eliminating unwanted portions in a format of 400 voxels × 400 voxels × septum thickness voxels. Then, the "IdentifyPores" function within the "PoroDict" function (a module of GeoDict) is used to derive the pore sizes in the 3D septum structure model M. The calculation method based on the IdentifyPores function in GeoDict involves watershed segmentation of the pores.

[0046] By analyzing the septum structure model M using the Identify Pores function described above, the fine pore size distribution and the values ​​of D10(m), D50(m), and D90(m) can be determined. It should be noted that the "Identify Pores function" used is the "Identify Pores function (2020 version)" from the aforementioned module of "GeoDict". "Identify Pores function (2020 version)" indicates the year (Gregorian calendar) in which this Identify Pores function is provided. Therefore, this analytical method is based on the analysis results using the Identify Pores function provided in 2020 (Gregorian calendar). Here, "2020 version" refers to the year (Gregorian calendar) provided within Japan, but it is not limited to this if the same analytical results are clearly obtained. Furthermore, if it is clear that the Identify Pores function provided in years other than 2020 (e.g., before or after 2020) can obtain the same analytical results as the aforementioned Identify Pores function (2020 version), then those functions can also be used for analysis.

[0047] In this embodiment, the cellular filter 100, based on the pore size distribution of the partition wall 1 obtained by the analytical method described above, defines the pore size (m) that accumulates to 90% of the total pore volume as D90 (m). Furthermore, in the following, in the pore size distribution of the partition wall 1 obtained by the analytical method, the pore size (m) that accumulates to 10% of the total pore volume is defined as D10 (m), and the pore size (m) that accumulates to 50% of the total pore volume is defined as D50 (m).

[0048] The average neck diameter (m) of the porous structure of partition 1 can be obtained using the analytical method described earlier. First, the partition structure model M is analyzed using the Identify Pores function, thereby dividing the pores in the partition structure model M into watershed sections. At this point, pores at the region ends are deleted, and the smallest detected pore diameter is 2 voxels. Furthermore, when the ratio of the interface between two contacting pores is greater than 30% of the pore's surface area, the two pores are merged into one pore. Then, according to the ascending order of the divided pore IDs, the Dilate function of the Process Geo module (2020 version) is used to replace the surrounding 2 voxels of the pores with other materials, thus obtaining the contact surfaces of the divided pore portions. Watershed division is then performed again on the contact surfaces of the divided pores, and the number of divisions is averaged to obtain the average neck diameter (average neck diameter). It should be noted that watershed segmentation refers to the segmentation of regions using the watershed algorithm.

[0049] In the pore size distribution of partition wall 1 obtained by this analytical method, there are no particular limitations, but D10(m) is preferably 5.0 × 10⁻⁶. -6 m or more and 2.5 × 10 -5 For m or less, 1.0 × 10 is more preferred. -5 m or more and 2.3 × 10 -5 Below m. By setting D10(m) to the numerical range mentioned above, there are advantages in improving capture efficiency, catalyst coating properties, and suppressing pressure loss increases. For example, by setting D10(m) to 5.0 × 10 -6 A value of m or higher is preferred for improved pressure loss performance and easier catalyst entry into the partition wall. On the other hand, setting D10(m) to 2.5 × 10⁻⁶ is also advantageous. -5 For samples with a depth of m or less, the preferred option is one that offers better capture performance.

[0050] Furthermore, in the pore size distribution of partition wall 1 obtained by this analytical method, D50(m) is preferably 1.7 × 10⁻⁶. -5 m or more and 4.1 × 10 -5 For m or less, 1.9 × 10 m is more preferred. -5 m or more and 3.9 × 10 -5 Below m. Setting D50(m) to the above-mentioned numerical range has advantages in improving collection efficiency and suppressing pressure loss increase. For example, setting D50(m) to 1.7 × 10 -5 For values ​​above m, better pressure loss performance is preferred. On the other hand, by setting D50(m) to 4.1 × 10-5 For samples with a depth of m or less, the preferred option is one that offers better capture performance.

[0051] The porosity of the septum 1 of the honeycomb filter 100 is preferably 33% or more and 65% or less. In this invention, the porosity of the septum 1 is a value obtained through structural analysis. Specifically, the porosity of the septum 1 is measured using the Open and Closed Porosity method in the "PoroDict function" of one of the modules of "GeoDict" described above. By making the porosity of the septum 1 33% or more and 65% or less, pressure loss can be reduced. By making the porosity of the septum 1 33% or more, the effect of reducing the pressure loss of the honeycomb filter 100 can be sufficiently obtained. On the other hand, by making the porosity of the septum 1 65% or less, the mechanical strength of the honeycomb filter 100 can be sufficiently maintained. The porosity of the septum 1 is further preferably 35% or more and 60% or less. It should be noted that the septum structure model M for determining the porosity of the septum 1 can be obtained using the same method as the "Identify Pores analytical method" used to determine the pore size distribution of the septum 1 described above.

[0052] There are no particular limitations on the thickness of the partition wall 1, but it is preferably 178 μm or more and 254 μm or less, and particularly preferably 191 μm or more and 241 μm or less. The thickness of the partition wall 1 can be measured, for example, using a scanning electron microscope or a microscope. If the thickness of the partition wall 1 is too thin, the collection performance may be reduced, which is not preferable. On the other hand, if the thickness of the partition wall 1 is too thick, it is not preferable in terms of increased pressure loss.

[0053] The compartment density of the compartments 2 formed by the partition 1 is preferably 43 compartments / cm³. 2 Above and 57 per cm 2 The following is more preferred: 47 per cm 2 Above and 54 per cm 2 The following is an explanation of how the honeycomb filter 100 can be suitably used as a filter for purifying exhaust gases emitted from the engine of a car.

[0054] There are no particular limitations on the shape of the compartments 2 formed in the honeycomb structure section 4. For example, the shape of the compartment 2 in a cross-section orthogonal to the direction in which the compartment 2 extends can be polygonal, circular, elliptical, etc. As a polygon, examples include triangle, quadrilateral, pentagon, hexagon, octagon, etc. It should be noted that the shape of the compartment 2 is preferably triangular, quadrilateral, pentagonal, hexagonal, or octagonal. In addition, in this utility model, the compartment 2 refers to the space surrounded by the partition wall 1.

[0055] Regarding the shape of the compartments 2 formed in the honeycomb structure portion 4, all compartments 2 can have the same shape or different shapes. For example, although not shown in the figure, quadrilateral and octagonal compartments may coexist. For example, it may be configured such that in a cross section of the honeycomb structure portion orthogonal to the direction in which the compartments extend, the shape of the outflowing compartment is different from the shape of the inflowing compartment. In such an arrangement, for example, it is preferable that the shape of the outflowing compartment is either quadrilateral or octagonal, and the shape of the inflowing compartment is either quadrilateral or octagonal.

[0056] Furthermore, regarding the size of the compartments 2 formed in the honeycomb structure section 4, all compartments 2 can be the same size or different sizes. For example, although the illustration is omitted, it is possible to increase the size of some of the multiple compartments while relatively decreasing the size of the other compartments.

[0057] The outer peripheral wall 3 of the honeycomb structure 4 can be integrally formed with the partition wall 1, or it can be an outer peripheral coating formed by applying an outer peripheral coating material to the outer peripheral side of the partition wall 1. For example, although the figure is omitted, during manufacturing, after the partition wall and the outer peripheral wall are integrally formed, the outer peripheral wall formed can be removed by known methods such as grinding, and then the outer peripheral coating can be applied to the outer peripheral side of the partition wall.

[0058] There are no particular limitations on the shape of the honeycomb structure section 4. Examples of the shape of the honeycomb structure section 4 include the first end face 11 (e.g., the inflow end face) and the second end face 12 (e.g., the outflow end face) being cylindrical, elliptical, polygonal, or similar shapes.

[0059] There are no particular limitations on the size of the honeycomb structure section 4, such as its length from the first end face 11 to the second end face 12, or the size of the cross section of the honeycomb structure section 4 that is orthogonal to the direction in which the compartment 2 extends. When using the honeycomb filter 100 as a filter for exhaust gas purification, each size can be appropriately selected in a way that obtains the best purification performance.

[0060] The material of partition 1 is not particularly limited, as long as it is a porous material that satisfies the porous structure of partition 1 described above. For example, as the material of partition 1, it is preferable to include at least one selected from the group consisting of silicon carbide, cordierite, silicon-silicon carbide composite material, cordierite-silicon carbide composite material, silicon nitride, mullite, alumina, and aluminum titanate. The material constituting partition 1 preferably contains 90% by mass or more of the materials listed in the above group, more preferably 92% by mass or more, and particularly preferably 95% by mass or more. It should be noted that silicon-silicon carbide composite material refers to a composite material formed with silicon carbide as aggregate and silicon as binder. In addition, cordierite-silicon carbide composite material refers to a composite material formed with silicon carbide as aggregate and cordierite as binder. In the honeycomb filter 100 of this embodiment, cordierite is particularly preferred as the material constituting partition 1.

[0061] The material of the sealing portion 5 is preferably the same as the material of the partition wall 1. The material of the sealing portion 5 and the material of the partition wall 1 can be the same or different.

[0062] The honeycomb filter 100 preferably has a catalyst for purifying exhaust gas supported on the partition walls 1 that divide the spacer into multiple compartments 2. Supporting the catalyst on the partition wall 1 means coating the surface of the partition wall 1 and the inner walls of the pores formed in the partition wall 1 with the catalyst. With this configuration, CO, NOx, HC, etc., in the exhaust gas can be converted into harmless substances through a catalytic reaction. Furthermore, it can promote the oxidation of PM such as coal particles captured. In the honeycomb filter 100 of this embodiment, it is particularly preferable to support the catalyst inside the pores of the porous partition wall 1. With this configuration, both improved capture performance and reduced pressure loss can be achieved simultaneously after catalyst loading at a low catalyst amount. Moreover, after catalyst loading, the gas flow becomes more uniform, thereby also promising improved purification performance.

[0063] There are no particular limitations on the catalyst supported on partition 1. For example, catalysts containing oxides of at least one of the elements selected from aluminum, zirconium, and cerium can be cited as examples of catalysts containing platinum group elements.

[0064] (2) Manufacturing method of honeycomb filter:

[0065] Next, the manufacturing method of the honeycomb filter according to this embodiment will be described. The honeycomb filter of this embodiment can be manufactured, for example, by the following method. First, a plastic clay for forming the honeycomb structure is prepared. The clay for forming the honeycomb structure can be prepared, for example, as follows: Talc, kaolin, alumina, aluminum hydroxide, and porous silica are prepared as raw material powders, and a water-absorbing polymer, binder, surfactant, and water are added as organic pore-forming materials to prepare the plastic clay. In particular, in the preparation of the clay, by adjusting the mixing ratio of the raw material powders and the organic pore-forming materials, the resulting partition wall can achieve a fine pore size distribution that satisfies the previously described porous structure's D90 (m) and average neck diameter (m).

[0066] Next, by extruding the resulting clay into shape, a honeycomb molded body is produced, which has partitions that divide into multiple compartments and an outer wall arranged around the partitions.

[0067] For example, the obtained honeycomb shaped body is dried using microwaves and hot air, and the openings of the compartments are sealed using the same material used to make the honeycomb shaped body, thereby creating the sealed sections. After creating the sealed sections, the honeycomb shaped body can be further dried.

[0068] Next, the honeycomb molded body with sealed pores is fired to manufacture a honeycomb filter. The firing temperature and firing atmosphere vary depending on the raw materials, and those skilled in the art can select the firing temperature and firing atmosphere most suitable for the selected materials.

[0069] Using the manufacturing method described above, it is possible to manufacture a honeycomb filter with a septum that achieves the previously described porous structure (i.e., D90 and average neck diameter).

[0070] Example

[0071] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments in any way.

[0072] (Example 1)

[0073] As forming raw materials for preparing blanks, talc, kaolin, alumina, aluminum hydroxide, a water-absorbing polymer, and porous silica were prepared. In Example 1, the forming raw materials were prepared by setting the proportions of each raw material in a chemical composition ranging from 42 to 56% by mass of silica, 30 to 45% by mass of alumina, and 12 to 16% by mass of magnesium oxide.

[0074] Next, relative to 100 parts by weight of the molding raw material from which the water-absorbing polymer has been removed, 2 parts by weight of the water-absorbing polymer as a pore-forming material, 6 parts by weight of the binder, and 1 part by weight of the dispersant were added to prepare a blank. The water-absorbing polymer with an average particle size of 20 μm was used as the pore-forming material. Methylcellulose was used as the binder. Potassium lauryl soap was used as the dispersant.

[0075] Next, the obtained clay is shaped using an extrusion molding machine to create a honeycomb molded body. Then, the honeycomb molded body is dried using high-frequency induction heating, followed by further drying using a hot air dryer. The cells in the honeycomb molded body are shaped as quadrilaterals.

[0076] Next, sealing portions are formed on the dried honeycomb molded body. First, a mask is applied to the inflow end face of the honeycomb molded body. Then, the masked end (the end on the inflow end face side) is immersed in sealing slurry, and the openings of the unmasked compartments (outflow compartments) are filled with sealing slurry. In this way, sealing portions are formed on the inflow end face side of the honeycomb molded body. Then, the same operation is performed on the outflow end face of the dried honeycomb molded body to form sealing portions in the inflow compartments as well.

[0077] Next, the honeycomb molded body with sealed pores is dried using a microwave dryer, and then further dried completely using a hot air dryer. The two ends of the honeycomb molded body are then cut off and adjusted to a predetermined size. Next, the dried honeycomb molded body is degreased and fired to manufacture the honeycomb filter of Example 1.

[0078] The honeycomb filter in Example 1 has an end face diameter of 304 mm and a cell length of 100 mm. Additionally, the cell wall thickness is 243 μm, and the cell density is 54 cells / cm³. 2 .

[0079] For the honeycomb filter of Example 1, the porosity of the partition walls was determined using the following method. The porosity of the partition walls was 53.2%.

[0080] (porosity)

[0081] The porosity of the partition wall was measured using the Open and Closed Porosity function within the PoroDict module, which is part of GeoDict. The specific analytical method is as described in this embodiment. Furthermore, the three-dimensional model and the partition wall structure model M were obtained using the same method as the "Identify Pores analytical method" described in this embodiment for determining the fine pore size distribution.

[0082] Furthermore, the pore size distribution of the septum of the honeycomb filter in Example 1 was determined using the Identify Pores analytical method. Based on the obtained pore size distribution (analytical values), the values ​​of D10 (m), D50 (m), and D90 (m) were calculated. It should be noted that D10 (m) represents the pore size (m) that accumulates to 10% of the total pore volume. D50 (m) represents the pore size (m) that accumulates to 50% of the total pore volume. D90 (m) represents the pore size (m) that accumulates to 90% of the total pore volume. A series of analyses based on the Identify Pores analytical method were performed using the previously described method, employing "GeoDict" (trade name), a microstructure simulation software developed by Math2Market GmbH. Additionally, the average neck diameter of the septum was determined using the aforementioned analytical method. The calculated values ​​of D10 (m), D50 (m), D90 (m), and average neck diameter (m) are shown in Table 1. Furthermore, the product of D90 (m) and average neck diameter (m) is calculated based on the values ​​of D90 (m) and average neck diameter (m). The result is shown in Table 1 as "D90 × Average Neck Diameter (m)". 2 )" column.

[0083] Table 1

[0084]

[0085] The cellular filter of Example 1 was evaluated for its capture performance using the following method. The results are shown in Table 1.

[0086] (Capture performance)

[0087] Calculate soot emission (kg / m³) using "FilterDict," which functions as GeoDict. 3 The three-dimensional data of the porous material were obtained using the "Identify Pores analytical method" described in this embodiment for determining the pore size distribution.

[0088] (Examples 2-9)

[0089] In Examples 2-9, the proportions (parts by mass) of the raw materials used for cordierite petrochemical were changed as follows. For the resulting honeycomb filters, the average neck diameter (m) and D90 (m) were determined using the same method as in Example 1. The results are shown in Table 1. In Examples 2-9, the average particle size, proportions, and amount of added water of the water-absorbing polymer or porous silica in the raw materials were changed.

[0090] (Comparative Examples 1-5)

[0091] In Comparative Examples 1-5, the proportions (parts by mass) of the raw materials used for cordierite petrochemical were changed as shown below. For the resulting honeycomb filters, the average neck diameter (m) and D90 (m) were determined using the same method as in Example 1. The results are shown in Table 1. In Comparative Examples 1-3, the average particle size, proportions, and amount of added water of the water-absorbing polymer or porous silica in the raw materials were changed. Furthermore, in some comparative examples, a pore-forming resin was added to the pore-forming material.

[0092] For the honeycomb filters of Examples 2-9 and Comparative Examples 1-5, the porosity of the partition walls was measured using the same method as in Example 1. Furthermore, for the honeycomb filters of Examples 2-9 and Comparative Examples 1-5, the pore size distribution of the partition walls was determined using the Identify Pores analytical method, and the values ​​of D10 (m) and D50 (m) were calculated based on the obtained pore size distribution (analytical values). The results are shown in Table 1.

[0093] The capture performance of the cellular filters of Examples 2-9 and Comparative Examples 1-5 was evaluated using the same method as in Example 1. The results are shown in Table 1.

[0094] (result)

[0095] The cellular filters of Examples 1-9 showed excellent results in the evaluation of their collection performance. In particular, the cellular filter of Example 1 had a smaller D90 (m) and a smaller average neck diameter (m), which resulted in high collection performance.

[0096] On the other hand, the collection performance of the cellular filters in Comparative Examples 1-5 was worse than that of the cellular filters in Examples 1-9. For example, compared with the cellular filter of Example 3, the cellular filters in Comparative Examples 1-3 had smaller D90 values ​​but poorer collection performance.

[0097] Industrial utilization potential

[0098] The honeycomb filter of this invention can be used as a trapping filter to remove particles and other contaminants contained in exhaust gas.

[0099] Symbol Explanation

[0100] 1—Block; 2—Compartment; 2a—Inflow compartment; 2b—Outflow compartment; 3—Outer peripheral wall; 4—Honeycomb structure section; 5—Sealing section; 11—First end face; 12—Second end face; 100—Honeycomb filter.

Claims

1. A honeycomb filter, characterized in that, have: The columnar honeycomb structure has porous partitions arranged to surround multiple compartments, which form a flow path for fluid extending from a first end face to a second end face. as well as A sealing portion, which is provided on the first end face side or the second end face side of each of the compartments. In the pore size distribution of the partition wall obtained through structural analysis, the pore size that accounts for 90% of the total pore volume is defined as D90. In the porous structure of the partition wall obtained through structural analysis, the average neck diameter is defined as the average value of the equivalent circle diameter of the neck that minimizes the flow path area of ​​the interconnecting pores in the porous structure. The product of D90 and the average neck diameter is 1.0 × 10⁻⁶. -10 m 2 Above and 9.0×10 -10 m 2 the following, The units for fine pore diameter, D90, average value, and average neck diameter are in meters (m).

2. The honeycomb filter according to claim 1, characterized in that, The D90 is 1.0 × 10 -5 m or more and 8.0 × 10 -5 Below m.

3. The honeycomb filter according to claim 1 or 2, characterized in that, The average neck diameter is 5.0 × 10⁻⁶. -6 m or more and 1.7 × 10 -5 Below m.

4. The honeycomb filter according to claim 1 or 2, characterized in that, In the pore size distribution of the partition wall obtained through the structural analysis, the pore size that accounts for 10% of the total pore volume is defined as D10. The D10 is 5.0 × 10 -6 m or more and 2.5 × 10 -5 Below m The unit of D10 is meters.

5. The honeycomb filter according to claim 1 or 2, characterized in that, In the pore size distribution of the partition wall obtained through the structural analysis, the pore size that accounts for 50% of the total pore volume is defined as D50. The D50 is 1.7 × 10⁻⁶. -5 m or more and 4.1 × 10 -5 Below m The unit of D50 is meters (m).

6. The honeycomb filter according to claim 1 or 2, characterized in that, The percentage of porosity of the partition wall, determined by the structural analysis, is above 33% and below 65%.

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