Plugged honeycomb structure

Abstract

To provide a plugged honeycomb structure capable of preventing a soot adhesion pressure loss from increasing due to PM deposition on a surface of a barrier.SOLUTION: The honeycomb structure includes: a honeycomb structural part 4 in a columnar shape having a porous barrier 1 arranged to surround a plurality of cells 2; and plugged parts 5 arranged on any one side of open end parts of the cells 2. In a cross section orthogonal to an extension direction of the cells 2, a gross area of inflow cells 2a is larger than a gross area of outflow cells 2b. A porosity of the barrier 1 is 38% or more. A thickness of the barrier 1 is 125 to 280 μm. A cell density of the honeycomb structural part 4 is 31.0 pcs. / cm2 or more. A permeation resistance of the barrier 1 is 4.5×107 Pa s / m2 or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a plugged honeycomb structure, and more particularly to a plugged honeycomb structure capable of realizing low pressure loss during use. [Background technology]

[0002] Internal combustion engines are used as a power source in various industries. On the other hand, the exhaust gas discharged from an internal combustion engine when burning fuel contains particulate matter such as soot and ash as well as toxic gases such as nitrogen oxides. Hereinafter, particulate matter may be referred to as "PM." "PM" is an abbreviation for "Particulate Matter." In recent years, regulations regarding the removal of PM emitted from diesel engines have become stricter worldwide, and as a filter for removing PM, for example, a wall flow type filter having a honeycomb structure is used.

[0003] As a wall-flow type filter, various plugged honeycomb structures have been proposed, each of which includes a honeycomb structure part in which a plurality of cells serving as a fluid flow path are partitioned by a porous partition wall, and a plugging part disposed at one of the openings of the plurality of cells (see, for example, Patent Documents 1 to 6). In such a plugged honeycomb structure, for example, inlet cells having plugging parts disposed at the outflow end face side and outlet cells having plugging parts disposed at the inflow end face side are alternately arranged with a partition wall between them, and the porous partition wall serves as a filter body for removing PM. In particular, a plugged honeycomb structure serving as a filter for removing PM discharged from a diesel engine is sometimes called a diesel particulate filter. Also, a plugged honeycomb structure serving as a filter for removing PM discharged from a gasoline engine is sometimes called a gasoline particulate filter. Hereinafter, the diesel particulate filter may be referred to as a "DPF" and the gasoline particulate filter may be referred to as a "GPF". [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 58-196820 [Patent Document 2] Patent No. 6068067 [Patent Document 3] JP 2015-29936 A [Patent Document 4] JP 2018-58761 A [Patent Document 5] JP 2018-143956 A [Patent Document 6] JP 2013-680 A Summary of the Invention [Problem to be solved by the invention]

[0005] DPFs require periodic cleaning maintenance because inorganic ash accumulates in engine oil during long-term operation. For this reason, it is expected that the inorganic ash accumulation capacity (hereinafter also referred to as "ash capacity") of DPFs will increase in order to reduce maintenance costs.

[0006] In order to increase the ash capacity, for example, it is possible to increase the ratio of inflow cells in the DPF, but in such a case, a cell arrangement in which the inflow cells are adjacent to each other is required, unlike a conventional DPF. Note that the above-mentioned conventional DPF refers to a DPF having a cell structure in which the inflow cells and the outflow cells are alternately arranged with partitions between them.

[0007] However, a DPF having a cell arrangement in which inlet cells are adjacent to each other may experience increased pressure loss when particulate matter such as soot is attached to the DPF (hereinafter also referred to as "soot-attached pressure loss") and increased pressure loss when no soot is attached (initial pressure loss). In other words, in a cell arrangement in which inlet cells are adjacent to each other, there is a partition wall (hereinafter also referred to as "in-in partition wall") that separates the inlet cells. A DPF having such an in-in partition wall has increased soot-attached pressure loss compared to a conventional DPF.

[0008] In this way, when the ash capacity is increased in order to reduce the pressure loss caused by the accumulation of inorganic ash (hereinafter also referred to as "pressure loss caused by ash accumulation"), the pressure loss caused by soot in the DPF increases, and there is a trade-off between the pressure loss caused by ash accumulation and the pressure loss caused by soot. For this reason, there is a demand for the development of a plugged honeycomb structure that can increase the ash capacity while reducing the pressure loss caused by soot.

[0009] The present invention has been made in consideration of the problems of the conventional techniques. The present invention provides a plugged honeycomb structure capable of realizing low pressure loss during use. In particular, the present invention provides a plugged honeycomb structure capable of realizing low pressure loss by increasing ash capacity and suppressing an increase in soot-related pressure loss caused by accumulation of PM on the partition wall surface. [Means for solving the problem]

[0010] According to the present invention, there is provided a plugged honeycomb structure as described below.

[0011] [1] A honeycomb structure having porous partition walls arranged to surround a plurality of cells that serve as fluid flow paths extending from an inflow end face to an outflow end face; and a plugging portion arranged to plug either one of the inlet end face side or the outlet end face side of the cell, the plugging portion is disposed at an end portion on the outflow end face side, and the cell having an opening on the inflow end face side is defined as an inflow cell, and the plugging portion is disposed at an end portion on the inflow end face side, and the cell having an opening on the outflow end face side is defined as an outflow cell, In a cross section of the honeycomb structure section perpendicular to the cell extension direction, the shape of the cells is polygonal, and one of the inlet cells and another of the inlet cells are adjacent to each other with the partition wall therebetween, and In the cross section perpendicular to the extension direction of the cells, the total area of ​​the inflow cells is larger than the total area of ​​the outflow cells, The porosity of the partition walls is 38% or more, the thickness of the partition walls is 125 μm or more and 280 μm or less, and the cell density of the honeycomb structure portion is 31.0 cells / cm 2 That's all. The air permeability resistance of the partition is 4.5×10 7 Pa·s / m 2 The plugged honeycomb structure is shown below.

[0012] [2] The air permeability resistance of the partition is 4.0×10 7 Pa·s / m 2 The plugged honeycomb structure according to the above [1],

[0013] [3] In the cross section perpendicular to the extension direction of the cells, the shape of one of the inlet cells and the shape of one of the outlet cells are congruent or similar, and The plugged honeycomb structure according to the above [1] or [2], wherein a ratio of a total number Na of the inflow cells to a total number Nb of the outflow cells is 2 or more.

[0014] [4] The plugged honeycomb structure according to any one of the above [1] to [3], wherein the inlet cells have one type of shape in the cross section perpendicular to the cell extension direction.

[0015] [5] The plugged honeycomb structure according to any one of [1] to [4], wherein in the cross section perpendicular to the cell extension direction, the inlet cells and the outlet cells each have a hexagonal shape.

[0016] [6] The plugged honeycomb structure according to any one of the above [1] to [5], wherein at least one of the cells has a shape of a regular hexagon in the cross section perpendicular to the extension direction of the cells.

[0017] [7] The plugged honeycomb structure according to any one of [1] to [6], wherein the partition walls support at least one catalyst selected from the group consisting of an oxidation catalyst, a selective catalytic reduction catalyst, and a three-way catalyst.

[0018] [8] The plugged honeycomb structure according to the above [7], wherein the oxidation catalyst is supported on the partition walls in an amount of 0.1 to 30 g / L.

[0019] [9] The plugged honeycomb structure according to the above [7], wherein the selective catalytic reduction catalyst is supported on the partition walls, and the supported amount of the selective catalytic reduction catalyst is 50 to 130 g / L.

[0020]

[10] The plugged honeycomb structure according to the above [7] or [9], wherein the selective catalytic reduction catalyst is a zeolite-type selective catalytic reduction catalyst or a vanadium-type selective catalytic reduction catalyst.

[0021]

[11] The plugged honeycomb structure according to the above [7], wherein the partition walls support the three-way catalyst in an amount of 40 to 130 g / L. Effect of the Invention

[0022] The plugged honeycomb structure of the present invention has a cell structure in which the cells have a polygonal shape in a cross section perpendicular to the cell extension direction of the honeycomb structure part, and one inflow cell is adjacent to another inflow cell with a partition wall sandwiched therebetween. The plugged honeycomb structure of the present invention is configured such that the total area of ​​the inflow cells is larger than the total area of ​​the outflow cells in the cross section of the honeycomb structure part, while the porosity, thickness and air permeation resistance of the partition wall, and the cell density of the honeycomb structure part are set to predetermined values.

[0023] The plugged honeycomb structure of the present invention configured as described above has an effect of realizing a lower pressure loss when used as a filter for collecting PM in exhaust gas, compared with a conventional plugged honeycomb structure. In particular, the plugged honeycomb structure of the present invention has a remarkable effect of suppressing an increase in soot-related pressure loss caused by accumulation of PM on the partition wall surface while increasing the ash capacity, thereby realizing a lower pressure loss. [Brief description of the drawings]

[0024] [Figure 1] 1 is a perspective view seen from an inflow end face side, which diagrammatically shows a first embodiment of a plugged honeycomb structure of the present invention. FIG. [Diagram 2] FIG. 2 is a plan view diagrammatically showing an inflow end face of the plugged honeycomb structure shown in FIG. [Diagram 3] 3 is an enlarged plan view of a portion of the inlet end face shown in FIG. 2. [Figure 4] FIG. 2 is a plan view diagrammatically showing the outflow end face of the plugged honeycomb structure shown in FIG. [Diagram 5] FIG. 3 is a cross-sectional view that diagrammatically shows the AA′ cross section of FIG. [Figure 6] FIG. 4 is a plan view illustrating an inflow end face of a plugged honeycomb structure according to a second embodiment of the present invention. [Figure 7] 7 is an enlarged plan view of a portion of the inlet end face shown in FIG. 6. FIG. [Figure 8] FIG. 7 is a plan view diagrammatically showing the outflow end face of the plugged honeycomb structure shown in FIG. [Figure 9] FIG. 7 is a cross-sectional view that diagrammatically shows the cross section BB' of FIG. [Figure 10] FIG. 11 is an enlarged plan view showing a part of an inflow end face of a plugged honeycomb structure according to a third embodiment of the present invention. [Figure 11] FIG. 11 is an enlarged plan view showing a part of the outflow end face of the plugged honeycomb structure shown in FIG. [Figure 12] FIG. 13 is an enlarged plan view showing a part of an inflow end face of a plugged honeycomb structure according to a fourth embodiment of the present invention. [Figure 13] FIG. 13 is an enlarged plan view showing a part of the outflow end face of the plugged honeycomb structure shown in FIG. [Figure 14] FIG. 13 is a perspective view seen from the inflow end face side, which diagrammatically shows a fifth embodiment of a plugged honeycomb structure of the present invention. [Figure 15] FIG. 15 is a perspective view, seen from the inflow end face side, that typically shows a honeycomb segment used in the plugged honeycomb structure shown in FIG. [Figure 16] FIG. 2 is an enlarged plan view showing a part of an inflow end face of a plugged honeycomb structure of Comparative Example 1. [Figure 17] FIG. 13 is an enlarged plan view showing a part of an inflow end face of a plugged honeycomb structure of Comparative Example 16. [Figure 18] 1 is a graph showing the relationship between permeation resistance (Pa·s / m2) and pressure drop increase ΔP (kPa) in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described. However, the present invention is not limited to the following embodiment. Therefore, it should be understood that appropriate changes, improvements, etc. can be made to the following embodiment based on the ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention.

[0026] (1) Plugged honeycomb structure (first embodiment): A plugged honeycomb structure 100 of a first embodiment will be described with reference to Figs. 1 to 5. Fig. 1 is a perspective view seen from the inflow end face side, which typically shows a plugged honeycomb structure according to a first embodiment of the present invention. Fig. 2 is a plan view typically showing the inflow end face of the plugged honeycomb structure shown in Fig. 1. Fig. 3 is an enlarged plan view in which a part of the inflow end face shown in Fig. 2 is enlarged. Fig. 4 is a plan view typically showing the outflow end face of the plugged honeycomb structure shown in Fig. 1. Fig. 5 is a cross-sectional view typically showing the A-A' cross section of Fig. 2.

[0027] The plugged honeycomb structure 100 includes a honeycomb structure portion 4 and plugging portions 5. The honeycomb structure portion 4 is columnar having an inflow end face 11 and an outflow end face 12. The honeycomb structure portion 4 has porous partition walls 1 arranged so as to surround a plurality of cells 2 extending from the inflow end face 11 to the outflow end face 12. The honeycomb structure portion 4 shown in FIG. 1 etc. further has an outer peripheral wall 3 arranged so as to surround the partition wall 1. In the present invention, the cell 2 means a space surrounded by the partition wall 1. The plurality of cells 2 serve as flow paths for a fluid.

[0028] The plugging portion 5 is disposed at either the inflow end face 11 side or the outflow end face 12 side of the cells 2 formed in the honeycomb structure portion 4, and serves to plug the openings of the cells 2. Hereinafter, the cell 2 having the plugging portion 5 disposed at the end on the outflow end face 12 side is referred to as the "inflow cell 2a." The cell 2 having the plugging portion 5 disposed at the end on the inflow end face 11 side is referred to as the "outflow cell 2b."

[0029] The plugged honeycomb structure 100 has a cell structure in which the shape of the cells 2 is polygonal in a cross section perpendicular to the extension direction of the cells 2 of the honeycomb structure portion 4, and one inflow cell 2a and another inflow cell 2a are adjacent to each other with a partition wall 1 sandwiched therebetween. Here, the cell structure means an arrangement pattern of a plurality of cells 2 formed by partitioning by the porous partition walls 1. That is, the plugged honeycomb structure 100 has an arrangement pattern in which two inflow cells 2a are adjacent to each other with a partition wall 1 sandwiched therebetween in the arrangement pattern of the cells 2 in the above cross section of the honeycomb structure portion 4. By having the above-mentioned cell structure in which one inflow cell 2a and another inflow cell 2a are adjacent to each other with a partition wall 1 sandwiched therebetween, the ash capacity of the plugged honeycomb structure 100 can be increased extremely effectively.

[0030] Moreover, the plugged honeycomb structure 100 is configured so that the total area of ​​the inflow cells 2a is larger than the total area of ​​the outflow cells 2b in a cross section perpendicular to the extension direction of the cells 2 of the honeycomb structure section 4. The total area of ​​the inflow cells 2a means the area of ​​each inflow cell 2a in the cross section of the honeycomb structure section 4 (in other words, the area of ​​each inflow cell2a The total area of ​​the outflow cells 2b refers to the sum of the areas of the outflow cells 2b (the opening areas of the outflow cells 2b) in the cross section of the honeycomb structure section 4. Hereinafter, when the "cross section" of the honeycomb structure section 4 is simply referred to, it refers to the "cross section perpendicular to the extension direction of the cells 2" of the honeycomb structure section 4. Furthermore, when the "area" and "total area" of the inflow cells 2a and the outflow cells 2b are simply referred to, it refers to the areas of the respective cells in the cross section of the honeycomb structure section 4.

[0031] In the embodiment in which the total area of ​​the inflow cells 2a is larger than the total area of ​​the outflow cells 2b, there is no particular restriction on the size relationship between the area of ​​each of the inflow cells 2a and the area of ​​each of the outflow cells 2b. That is, the area of ​​each of the inflow cells 2a and the area of ​​each of the outflow cells 2b may be the same or different. For example, when the area of ​​each of the inflow cells 2a and the area of ​​each of the outflow cells 2b are the same, the total area of ​​the inflow cells 2a may be configured to be larger by making the total number Na of the inflow cells 2a relatively larger than the total number Nb of the outflow cells 2b. Also, even if the area of ​​each of the inflow cells 2a is smaller than the area of ​​each of the outflow cells 2b, the total area of ​​the inflow cells 2a may be configured to be larger by making the total number Na of the inflow cells 2a relatively larger. On the other hand, when the area of ​​each of the inflow cells 2a is larger than the area of ​​each of the outflow cells 2b, the total number Na of the inflow cells 2a and the total number Nb of the outflow cells 2b may be appropriately set so that the total area of ​​the inflow cells 2a is larger.

[0032] In the plugged honeycomb structure 100, it is preferable that in the cross section of the honeycomb structure portion 4, the shape of one inflow cell 2a and the shape of one outflow cell 2b are congruent or similar, and the ratio of the total number Na of the inflow cells 2a to the total number Nb of the outflow cells 2b is 2 or more. Hereinafter, the "ratio of the total number Na of the inflow cells 2a to the total number Nb of the outflow cells 2b" may be referred to as the cell number ratio (Na / Nb). For example, the plugged honeycomb structure 100 shown in Figs. 1 to 5 satisfies the relationship of "total number Na of the inflow cells 2a:total number Nb of the outflow cells 2b=2:1", and the cell number ratio (Na / Nb) is 2.

[0033] In the plugged honeycomb structure 100 shown in Figs. 1 to 5, the shapes of the inflow cells 2a and the outflow cells 2b are both hexagonal in the cross section of the honeycomb structure section 4. The shapes of the inflow cells 2a and the outflow cells 2b in the cross section of the honeycomb structure section 4 are not limited to hexagonal, and may be other polygonal shapes such as triangles, rectangles, pentagons, and octagons. Hereinafter, the "shape of the cells 2" in the cross section perpendicular to the extension direction of the cells 2 of the honeycomb structure section 4 may be referred to as the "cross-sectional shape of the cells 2" or simply as the "shape of the cells 2". In this specification, the term "polygonal" includes various polygonal shapes, shapes in which at least one corner of the polygon is curved, and shapes in which at least one corner of the polygon is chamfered linearly. For example, the term "hexagonal" includes a hexagon, a shape in which at least one corner of the hexagon is curved, and a shape in which at least one corner of the hexagon is chamfered linearly.

[0034] In the cross section of the honeycomb structure portion 4, the inflow cells 2a may have one type of shape or two or more types. Similarly, the outflow cells 2b may have one type of shape or two or more types. In the plugged honeycomb structure 100, the inflow cells 2a preferably have one type of shape.

[0035] In the plugged honeycomb structure 100, it is preferable that the shape of one inflow cell 2a and the shape of one outflow cell 2b are congruent or similar in the cross section of the honeycomb structure portion 4. For example, when the shape of one of the plurality of inflow cells 2a is a hexagon, at least one of the plurality of outflow cells 2b is a hexagon. Shape of effusion cell 2b It is preferable that the shape of the inlet cells 2a and the outflow cells 2b is a regular hexagon. In the plugged honeycomb structure 100 shown in Figs. 1 to 5, the shape of each of the inlet cells 2a and the outflow cells 2b is a regular hexagon. It is preferable that the shape of at least one of the cells 2 is a regular hexagon.

[0036] In the plugged honeycomb structure 100, the porosity of the partition walls 1 of the honeycomb structure portion 4 is 38% or more. If the porosity of the partition walls 1 is less than 38%, the pressure loss may increase. The porosity of the partition walls 1 is preferably 38 to 75%, and more preferably 38 to 65%. For example, if the porosity of the partition walls 1 is too high, the strength of the honeycomb structure portion 4 becomes insufficient, and when the plugged honeycomb structure 100 is housed in a can body used in an exhaust gas purification device, it may become difficult to hold the plugged honeycomb structure 100 with sufficient gripping force. The porosity of the partition walls 1 is a value measured by a mercury porosimeter. As the mercury porosimeter, for example, Autopore 9500 (product name) manufactured by Micromeritics can be mentioned.

[0037] In the plugged honeycomb structure 100, the thickness T of the partition wall 1 is 125 μm or more and 280 μm or less. By configuring in this way, it is possible to obtain a plugged honeycomb structure 100 with low pressure loss while maintaining isostatic strength. The thickness T of the partition wall 1 is preferably 125 μm or more and 254 μm or less, and more preferably 125 μm or more and 228 μm or less. The thickness T of the partition wall 1 is the length in the direction perpendicular to the surface of the partition wall 1 that divides two cells 2 in the cross section of the honeycomb structure section 4. Here, as shown in FIG. 3, the partition wall 1 disposed between the inlet cell 2a and the outlet cell 2b is referred to as the "first partition wall 1a", and the partition wall 1 disposed between the inlet cells 2a is referred to as the "second partition wall 1b". In the plugged honeycomb structure 100, the thickness T1 of the first partition wall 1a and the thickness T2 of the second partition wall 1b are both 125 μm or more and 280 μm or less. The thickness T1 of the first partition wall 1a and the thickness T2 of the second partition wall 1b may be the same or different. It is preferable that the thickness T1 of the first partition wall 1a and the thickness T2 of the second partition wall 1b are the same. The thickness T of the partition wall 1 can be measured using, for example, a microscope. As the microscope, for example, VHX-1000 (product name) manufactured by Keyence Corporation can be used.

[0038] The plugged honeycomb structure 100 has a honeycomb structure portion 4 with a cell density of 31.0 cells / cm 2 This is the end of the description. With this configuration, the honeycomb structure portion 4 can be suitably used as a filter for collecting PM in exhaust gas discharged from the engine of an automobile, etc. The cell density of the honeycomb structure portion 4 is 31 cells / cm 2 More than 70 pieces / cm 2 Preferably, 31 pieces / cm or less. 2 More than 62 pieces / cm 2 It is even more preferable that:

[0039] In a cell arrangement in which the inflow cells 2a are adjacent to each other, there is a partition wall 1 (hereinafter also referred to as "IN-IN partition wall") that separates the inflow cells 2a. In a DPF having such an IN-IN partition wall, the initial pressure loss and the pressure loss due to soot increase compared to a conventional DPF due to the way the gas flows. For example, although not shown, in a conventional DPF, when gas flows through the partition wall "IN-OUT partition wall" between the inflow cell and the outflow cell, the gas permeates through the thickness of the soot and the partition wall thickness. In comparison, in a DPF having both the IN-IN partition wall and the IN-OUT partition wall as in this embodiment, when there is no soot, the gas flow concentrates on the IN-OUT partition wall, and a higher pressure loss occurs than in the conventional type. In addition, as soot accumulates, the gas begins to flow in a dispersed manner in the IN-IN wall, and as the accumulation of soot and ash progresses and the deposit resistance increases, the pressure loss is reduced compared to the conventional type. Therefore, the DPF having the IN-IN wall has a greater effect of lowering the permeation resistance of the partition wall 1 than the conventional type.

[0040] In the plugged honeycomb structure 100, the air permeation resistance of the partition wall 1 is 4.5×10 7 Pa·s / m 2 The air permeability resistance of the partition wall 1 is 4.5×10 7 Pa·s / m 2If the upper limit of the air permeation resistance of the partition wall 1 exceeds 1.0×10, for example, in a plugged honeycomb structure 100 having a cell structure in which two inlet cells 2a are adjacent to each other with a partition wall 1 therebetween, the pressure loss due to soot caused by accumulation of PM on the surface of the partition wall 1 increases. 5 Pa·s / m 2 Therefore, the air permeability resistance of the partition 1 is 1.0×10 5 Pa·s / m 2 That's it, 4.5 x 10 7 Pa·s / m 2 It is preferable that the value is less than 1.0×10 6 Pa·s / m 2 That's it, 4.0 x 10 7 Pa·s / m 2 It is even more preferable that:

[0041] The air permeation resistance of the partition walls 1 can be measured by the following method. First, some partition walls 1 are cut out from the honeycomb structure portion 4 of the plugged honeycomb structure 100. There are no particular limitations on the location (position) from which the partition walls 1 are cut out, but for example, in the case of a plugged honeycomb structure having a segment structure described later, the partition walls 1 can be cut out from a portion of the segment outer wall formed of the same material, but it is preferable to process the portion constituting the partition walls 1 into a flat plate. Then, air at 25°C is passed through the cut out partition wall 1 while changing the flow rate using a mass flow meter, and the differential pressure of the air before and after passing through the partition wall 1 at this time is measured using a pressure gauge. Then, the unit area (mm 2 ) air permeability resistance (Pa s / m 2 More specifically, the flow rate (L / min) is converted to flow velocity (m / s) by dividing the flow rate of the mass flow meter by the area of ​​the partition wall 1. of Divide by the thickness (m) to get the unit area (mm 2 ) is measured. The slope of the X-axis flow velocity (m / s) and the Y-axis pressure difference (Pa / m) is used to calculate the unit area (mm 2 ) air permeability resistance (Pa s / m 2 The flow rate is measured in the range of 0.1 to 1 m / s.

[0042] The plugged honeycomb structure 100 configured as above can be suitably used as, for example, a filter for collecting PM in exhaust gas. The plugged honeycomb structure 100 can realize a low pressure loss when used as a filter for collecting PM in exhaust gas, compared with a conventional plugged honeycomb structure. In particular, the plugged honeycomb structure 100 of the present embodiment has a cell structure in which one inlet cell 2a and another inlet cell 2a are adjacent to each other with the partition wall 1 therebetween, and is configured so that the total area of ​​the inlet cells 2a is larger than the total area of ​​the outflow cells 2b, so that the ash capacity can be effectively increased. Furthermore, with the above-mentioned configuration, while increasing the ash capacity, an increase in soot-attached pressure loss due to accumulation of PM on the surface of the partition wall 1 can be suppressed, and a lower pressure loss can be realized.

[0043] Furthermore, in the plugged honeycomb structure 100, the total opening ratio of the honeycomb structure portion 4 is preferably greater than 35% and equal to or less than 95%. Here, the "total opening ratio" of the honeycomb structure portion 4 means the percentage of the ratio of the total opening area of ​​the cells 2 formed in the honeycomb structure portion 4 to the cross-sectional area perpendicular to the extension direction of the cells 2 of the honeycomb structure portion 4. Note that the cross-sectional area perpendicular to the extension direction of the cells 2 of the honeycomb structure portion 4 does not include the area of ​​the peripheral wall 3 arranged on the outermost periphery of the honeycomb structure portion 4.

[0044] The average pore diameter of the partition walls 1 is not particularly limited, but is preferably 7 to 25 μm, and more preferably 9 to 20 μm. The average pore diameter of the partition walls 1 is a value measured with a mercury porosimeter. An example of the mercury porosimeter is Autopore 9500 (product name) manufactured by Micromeritics.

[0045] In the plugged honeycomb structure 100, the partition walls 1 disposed so as to surround the inlet cells 2a have a geometric surface area of ​​1.00 to 1.40 cm 2 / cm 3It is preferable that the thickness is 1.10 to 1.40 cm. 2 / cm 3 It is more preferable that the geometric surface area is 100 mm or less. Here, the above-mentioned "geometric surface area" refers to the value (S / V) obtained by dividing the total inner surface area (S) of the inlet cells 2a by the total volume (V) of the honeycomb structure portion. In general, the larger the filtration area of ​​the filter, the more the thickness of PM deposition on the partition wall 1 arranged to surround the inlet cells 2a can be reduced, so that the pressure loss of the plugged honeycomb structure can be suppressed low by setting the geometric surface area within the above-mentioned numerical range. Therefore, if the geometric surface area of ​​the inlet cells 2a is too small, it is not preferable because it may lead to an increase in pressure loss due to soot during PM deposition. In addition, if the geometric surface area of ​​the inlet cells 2a is too large, it is not preferable because it may increase initial pressure loss. Hereinafter, the above-mentioned geometric surface area may be referred to as "GSA" or "geometric surface area GSA". GSA is an abbreviation for "Geometric Surface Area".

[0046] There is no particular limitation on the material of the partition wall 1. For example, ceramics can be used as the material of the partition wall 1. In particular, it is preferable that the partition wall 1 contains silicon carbide, silicon-bonded silicon carbide, a binder sintered ceramic material, mullite, cordierite, or aluminum titanate. The term "silicon-bonded silicon carbide" refers to a material in which silicon carbide particles as an aggregate are bonded by metallic silicon, as shown in Japanese Patent Publication No. 4136319. The term "binder sintered ceramic material" refers to a ceramic material produced by sintering, in which aggregates such as silicon carbide or mullite are bonded by a binder such as cordierite, as shown in Japanese Patent Publication No. 2015-67473.

[0047] The material of the plugging portion 5 is not particularly limited, but the materials exemplified above as the materials of the partition wall 1 can be suitably used.

[0048] There is no particular limitation on the overall shape of the plugged honeycomb structure 100. The overall shape of the plugged honeycomb structure 100 is preferably such that the inflow end face 11 and the outflow end face 12 are circular or elliptical, and particularly preferably circular. There is no particular limitation on the size of the plugged honeycomb structure 100, for example, the length from the inflow end face 11 to the outflow end face 12 of the honeycomb structure part 4, or the size of the cross section perpendicular to the extension direction of the cells 2 of the honeycomb structure part 4. Each size may be appropriately selected so as to obtain optimal purification performance when the plugged honeycomb structure 100 is used as a filter for purifying exhaust gas.

[0049] The plugged honeycomb structure 100 can be suitably used as a member for purifying exhaust gas from an internal combustion engine. The plugged honeycomb structure 100 may be one in which a catalyst for purifying exhaust gas is supported on at least one of the surfaces of the partition walls 1 of the honeycomb structure portion 4 and the pores of the partition walls 1. For example, examples of the catalyst for purifying exhaust gas include an oxidation catalyst, a selective catalytic reduction catalyst, and a three-way catalyst.

[0050] The oxidation catalyst may be a catalyst containing a precious metal. Specific examples of the oxidation catalyst include those containing at least one selected from the group consisting of platinum (Pt), palladium (Pd) and rhodium (Rh). When the oxidation catalyst is supported on the partition wall 1, the amount of the oxidation catalyst supported is preferably 0.1 to 30 g / L. Here, the amount of the catalyst supported (g / L) refers to the amount (g) of the catalyst supported per unit volume (1 L) of the honeycomb structure portion 4.

[0051] A selective catalytic reduction catalyst is a catalyst that selectively reduces components to be purified. Hereinafter, the selective catalytic reduction catalyst is also referred to as an "SCR catalyst." "SCR" is an abbreviation for "Selective Catalytic Reduction." The selective catalytic reduction catalyst is preferably a zeolite-type selective catalytic reduction catalyst or a vanadium-type selective catalytic reduction catalyst. The zeolite-type selective catalytic reduction catalyst refers to a catalyst that contains a catalytically active component that contains zeolite. As the zeolite-type selective catalytic reduction catalyst, for example, a selective catalytic reduction catalyst that contains a metal-substituted zeolite can be mentioned. As the metal that substitutes the zeolite, iron (Fe) and copper (Cu) can be mentioned. As the zeolite, A-type, X-type, CHA-type, LTA-type, MFI-type, FER-type, FAU-type, DDR-type, and beta zeolite can be mentioned as suitable examples. The vanadium-type selective catalytic reduction catalyst refers to a catalyst that contains a catalytically active component that contains vanadium. Examples of vanadium-type selective catalytic reduction catalysts include catalysts containing vanadium or tungsten as the main component. The amount of the selective catalytic reduction catalyst supported is preferably 50 to 130 g / L.

[0052] A three-way catalyst is a catalytic converter that mainly converts hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO X The term "three-way catalyst" refers to a catalyst that purifies the above-mentioned substances. Examples of three-way catalysts include catalysts containing platinum (Pt), palladium (Pd), and rhodium (Rh). The amount of the three-way catalyst supported is preferably 40 to 130 g / L.

[0053] Next, a method for manufacturing the plugged honeycomb structure of the present embodiment will be described, although the method for manufacturing the plugged honeycomb structure is not limited to the manufacturing method described below.

[0054] First, a plastic clay for producing the honeycomb structure is prepared. The clay for producing the honeycomb structure can be prepared by adding additives such as a binder and water as appropriate to a material selected from the above-mentioned group of suitable materials for the partition walls as a raw material powder.

[0055] Next, the produced clay is extrusion molded to obtain a columnar honeycomb molded body having partition walls that divide a plurality of cells and an outer peripheral wall disposed on the outermost periphery. In the extrusion molding, a die for extrusion molding can be used that has slits formed on the extrusion surface of the clay to form an inverted shape of the honeycomb molded body to be molded. The obtained honeycomb molded body may be dried, for example, by microwaves and hot air.

[0056] Next, the openings of the cells are plugged with the same material as that used in the production of the honeycomb formed body to form plugged portions. The method for forming the plugged portions can be performed according to a conventional method for producing a plugged honeycomb structure.

[0057] Next, the honeycomb formed body thus obtained is fired to obtain a plugged honeycomb structure. The firing temperature and firing atmosphere vary depending on the raw materials, and a person skilled in the art can select the optimum firing temperature and firing atmosphere for the selected materials.

[0058] (2) Plugged honeycomb structure (second embodiment): Next, a plugged honeycomb structure 200 of a second embodiment will be described with reference to Fig. 6 to Fig. 9. Fig. 6 is a plan view typically showing an inflow end face of a plugged honeycomb structure of a second embodiment of the present invention. Fig. 7 is an enlarged plan view of a part of the inflow end face shown in Fig. 6. Fig. 8 is a plan view typically showing an outflow end face of the plugged honeycomb structure shown in Fig. 6. Fig. 9 is a cross-sectional view typically showing the B-B' cross section of Fig. 6.

[0059] The plugged honeycomb structure 200 includes a honeycomb structure portion 4 and plugging portions 5. The honeycomb structure portion 4 is columnar having an inflow end face 11 and an outflow end face 12. The honeycomb structure portion 4 has porous partition walls 1 arranged so as to surround a plurality of cells 2 extending from the inflow end face 11 to the outflow end face 12. The plugging portions 5 are arranged at either one of the ends on the inflow end face 11 side or the outflow end face 12 side of the cells 2 formed in the honeycomb structure portion 4, and plug the openings of the cells 2.

[0060] The plugged honeycomb structure 200 has a cell structure in which the cells 2 have a polygonal shape in a cross section perpendicular to the extension direction of the cells 2 of the honeycomb structure portion 4, and one inlet cell 2a is adjacent to another inlet cell 2a with a partition wall 1 sandwiched therebetween.

[0061] In the plugged honeycomb structure 200, the shapes of the inflow cells 2a and the outflow cells 2b are both hexagonal in the cross section of the honeycomb structure portion 4. However, the plugged honeycomb structure 200 is different from the plugged honeycomb structure 100 (see Figs. 1 to 5) of the first embodiment described above in the numbers and arrangements of the inflow cells 2a and the outflow cells 2b. Specifically, the plugged honeycomb structure 200 shown in Figs. 6 to 9 satisfies the relationship "total number Na of inflow cells 2a:total number Nb of outflow cells 2b=3:1", and the cell number ratio (Na / Nb) is 3. The plugged honeycomb structure 200 is configured such that the total area of ​​the inflow cells 2a is larger than the total area of ​​the outflow cells 2b in the cross section of the honeycomb structure portion 4.

[0062] In the plugged honeycomb structure 200, the porosity of the partition walls 1 is 38% or more, and the thickness of the partition walls 1 is 125 μm or more and 280 μm or less. In addition, in the plugged honeycomb structure 200, the cell density of the honeycomb structure portion 4 is 31.0 cells / cm 2 Furthermore, in the plugged honeycomb structure 200, the air permeation resistance of the partition wall 1 is 4.5×10 7 Pa·s / m 2 The porosity, thickness and air permeation resistance of the partition walls 1, and the cell density of the honeycomb structure portion 4 are preferably configured similarly to the plugged honeycomb structure 100 of the first embodiment (see Figs. 1 to 5).

[0063] The plugged honeycomb structure 200 is preferably configured similarly to the plugged honeycomb structure 100 of the first embodiment (see Figs. 1 to 5) except that the numbers and arrangements of the inlet cells 2a and the outflow cells 2b are different as described above. In Figs. 6 to 9, the same components as those of the plugged honeycomb structure 100 shown in Figs. 1 to 5 are denoted by the same reference numerals, and the description thereof may be omitted.

[0064] The plugged honeycomb structure 200 configured as above can also realize a low pressure loss when used as a filter for collecting PM in exhaust gas, compared with a conventional plugged honeycomb structure. Like the plugged honeycomb structure 100 of the first embodiment described above (see Figs. 1 to 5), an increase in the ash capacity is increased while suppressing an increase in soot-related pressure loss due to accumulation of PM on the surfaces of the partition walls 1, thereby realizing a lower pressure loss.

[0065] (3) Plugged honeycomb structure (third embodiment): Next, a plugged honeycomb structure 300 of a third embodiment will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is an enlarged plan view of a part of an inflow end face of a plugged honeycomb structure of a third embodiment of the present invention. Fig. 11 is an enlarged plan view of a part of an outflow end face of the plugged honeycomb structure shown in Fig. 10.

[0066] The plugged honeycomb structure 300 includes a honeycomb structure portion 24 having a columnar shape with an inflow end face 31 and an outflow end face 32, and plugging portions 25. The honeycomb structure portion 24 is configured to have, for example, a cylindrical shape with an inflow end face 31 and an outflow end face 32, similar to the plugged honeycomb structure 100 of the first embodiment described above (see Figs. 1 to 5). The honeycomb structure portion 24 has porous partition walls 21 disposed so as to surround a plurality of cells 22 extending from the inflow end face 31 to the outflow end face 32. The plugging portions 25 are disposed at either one end of the inflow end face 31 side or the outflow end face 32 side of the cells 22 formed in the honeycomb structure portion 24, and plug the openings of the cells 22.

[0067] The plugged honeycomb structure 300 has a cell structure in which the shape of the cells 22 is polygonal in a cross section perpendicular to the extending direction of the cells 22 of the honeycomb structure portion 24, and one inflow cell 22a is adjacent to another inflow cell 22a with a partition wall 21 sandwiched therebetween. Specifically, the shape of the cells 22 is rectangular and octagonal, and the rectangular cells 22 and the octagonal cells 22 are alternately arranged with the partition wall 21 sandwiched therebetween in the vertical and horizontal directions of the paper plane of Figs. 10 and 11. In the plugged honeycomb structure 300, when the areas of the rectangular cells 22 and the octagonal cells 22 are compared, the octagonal cells 22 are configured so that their areas are larger. The octagonal cells 22 are inflow cells 22a with plugging portions 25 disposed at the end portions on the outflow end face 32 side. On the other hand, the rectangular cells 22 are outflow cells with plugging portions 25 disposed at the end portions on the inflow end face 31 side. 22b Therefore, the plugged honeycomb structure 300 is configured so that the total area of ​​the inflow cells 22a is larger than the total area of ​​the outflow cells 22b in the cross section of the honeycomb structure portion 24. The octagonal inflow cells 22a having a relatively large area are arranged adjacent to each other with the partition wall 21 interposed therebetween in the diagonal direction of the paper of Figs. 10 and 11. Therefore, the plugged honeycomb structure 300 has a cell structure in which one inflow cell 22a and another inflow cell 22a are adjacent to each other with the partition wall 21 interposed therebetween in the diagonal direction of the paper of Figs. 10 and 11.

[0068] In the plugged honeycomb structure 300, the partition walls 21 have a porosity of 38% or more and a thickness of 125 μm or more and 280 μm or less. In addition, in the plugged honeycomb structure 300, the honeycomb structure portion 24 has a cell density of 31.0 cells / cm 2 Furthermore, in the plugged honeycomb structure 300, the air permeation resistance of the partition walls 21 is 4.5×10 7 Pa·s / m 2 The porosity, thickness and air permeation resistance of the partition walls 21, and the cell density of the honeycomb structure portion 24 are preferably configured similarly to the plugged honeycomb structure 100 of the first embodiment (see Figs. 1 to 5).

[0069] The plugged honeycomb structure 300 configured as described above, when used as a filter for capturing PM in exhaust gas, can increase the ash capacity while suppressing an increase in soot-related pressure loss caused by accumulation of PM on the surfaces of the partition walls 21, thereby achieving lower pressure loss, compared to conventional plugged honeycomb structures.

[0070] (4) Plugged honeycomb structure (fourth embodiment): Next, a plugged honeycomb structure 400 of a fourth embodiment will be described with reference to Fig. 12 and Fig. 13. Fig. 12 is an enlarged plan view of a part of an inflow end face of a plugged honeycomb structure of a fourth embodiment of the present invention. Fig. 13 is an enlarged plan view of a part of an outflow end face of the plugged honeycomb structure shown in Fig. 12.

[0071] The plugged honeycomb structure 400 includes a honeycomb structure portion 24 having a columnar shape with an inflow end face 31 and an outflow end face 32, and plugging portions 25. The honeycomb structure portion 24 is configured to have, for example, a cylindrical shape with an inflow end face 31 and an outflow end face 32, similar to the plugged honeycomb structure 100 of the first embodiment described above (see Figs. 1 to 5). The honeycomb structure portion 24 has porous partition walls 21 disposed so as to surround a plurality of cells 22 extending from the inflow end face 31 to the outflow end face 32. The plugging portions 25 are disposed at either one end of the inflow end face 31 side or the outflow end face 32 side of the cells 22 formed in the honeycomb structure portion 24, and plug the openings of the cells 22.

[0072] In the plugged honeycomb structure 400, the shape of the cells 22 is a rectangle and an octagon in the cross section of the honeycomb structure portion 24, similarly to the plugged honeycomb structure 300 of the third embodiment described so far (see Figs. 10 and 11). The rectangular cells 22 and the octagonal cells 22 are alternately arranged with the partition walls 21 interposed therebetween in the vertical and horizontal directions of the paper plane of Figs. 12 and 13. However, the plugged honeycomb structure 400 is different from the plugged honeycomb structure 300 of the third embodiment (see Figs. 10 and 11) in the number and arrangement of the inflow cells 22a and the outflow cells 22b. Specifically, in the plugged honeycomb structure 400, the inflow cells 22a and the outflow cells 22b are arranged such that, when one octagonal cell 22 is defined as an outflow cell 22b, the eight cells 22 arranged around the outflow cell 22b are defined as the inflow cell 22a. The eight inflow cells 22a arranged around the octagonal outflow cell 22b are composed of four octagonal cells 22 and four quadrangular cells 22, and the octagonal cells 22 and the quadrangular cells 22 are arranged so as to alternately surround the octagonal outflow cell 22b. Therefore, the plugged honeycomb structure 400 has a cell structure in which the octagonal inflow cells 22a and the quadrangular inflow cells 22a are adjacent to each other with the partition wall 21 interposed therebetween. Furthermore, the plugged honeycomb structure 400 is configured so that the total area of ​​the inflow cells 22a is larger than the total area of ​​the outflow cells 22b in the cross section of the honeycomb structure portion 24.

[0073] Plugged honeycomb structure 400 In the plugged honeycomb structure 400, the porosity of the partition walls 21 is 38% or more, and the thickness of the partition walls 21 is 125 μm or more and 280 μm or less. In addition, in the plugged honeycomb structure 400, the cell density of the honeycomb structure portion 24 is 31.0 cells / cm 2 The above is the result. 400 The air permeability resistance of the partition 21 is 4.5×10 7 Pa·s / m 2 The porosity, thickness and air permeation resistance of the partition walls 21, and the cell density of the honeycomb structure portion 24 are preferably configured similarly to the plugged honeycomb structure 300 of the third embodiment (see Figs. 10 and 11).

[0074] Note that the plugged honeycomb structure 400 is preferably configured similarly to the plugged honeycomb structure 300 of the third embodiment (see Figs. 10 and 11) except for the different arrangement of the inlet cells 22a and the outlet cells 22b as described above. In Figs. 12 and 13, the same components as those of the plugged honeycomb structure 300 shown in Figs. 10 and 11 are denoted by the same reference numerals, and the description thereof may be omitted. Note that the area surrounded by the dotted line in Fig. 12 indicates the minimum repeating unit (one unit) in the cell structure of the plugged honeycomb structure 400.

[0075] The plugged honeycomb structure 400 configured as described above, when used as a filter for capturing PM in exhaust gas, can increase the ash capacity while suppressing an increase in soot-related pressure loss caused by accumulation of PM on the surfaces of the partition walls 21, thereby achieving lower pressure loss, compared to conventional plugged honeycomb structures.

[0076] (5) Plugged honeycomb structure (fifth embodiment): Next, a plugged honeycomb structure 700 of a fifth embodiment will be described with reference to Fig. 14 and Fig. 15. Fig. 14 is a perspective view seen from the inflow end face side, which typically shows the fifth embodiment of the plugged honeycomb structure of the present invention. Fig. 15 is a perspective view seen from the inflow end face side, which typically shows a honeycomb segment used in the plugged honeycomb structure shown in Fig. 14.

[0077] As shown in Fig. 14, a plugged honeycomb structure 700 of the fifth embodiment is a plugged honeycomb structure 700 including a honeycomb structure portion 84 having a segment structure. That is, in the plugged honeycomb structure 700, the honeycomb structure portion 84 is constituted by a plurality of columnar honeycomb segments 86, and the side surfaces of the plurality of honeycomb segments 86 are bonded to each other by a bonding layer 87. Here, the "segmented honeycomb structure portion 84" refers to a honeycomb structure portion 84 in which a plurality of honeycomb segments 86, which are individually manufactured, are bonded to each other by a bonding layer 87. Note that a honeycomb structure portion 4 in which the partition walls 1 are all integrally formed as shown in Figs. 1 to 5, may be referred to as an "integral honeycomb structure portion 4". The honeycomb structure part in the plugged honeycomb structure of the present invention may be a "segment-structured honeycomb structure part 84" as shown in Fig. 14, or may be, for example, an "integral honeycomb structure part 4" as shown in Fig. 1. Note that Fig. 14 is drawn in such a manner that the partition walls and cells on the inflow end face 91 of each honeycomb segment 86 are omitted.

[0078] As shown in Fig. 14, a plugged honeycomb structure 700 includes a columnar honeycomb structure portion 84 having an inflow end face 91 and an outflow end face 92. As shown in Fig. 15, a honeycomb segment 86 constituting the honeycomb structure portion 84 includes porous partition walls 81 arranged so as to surround a plurality of cells 82 extending from the inflow end face 91 to the outflow end face 92. The honeycomb segment 86 further includes a segment outer wall 88 arranged so as to surround the partition wall 81.

[0079] A plugging portion 85 is disposed at either one of the ends on the inflow end face 91 side or the outflow end face 92 side of the cells 82 formed in the honeycomb segment 86. As a result, the cells 82 having the plugging portion 85 disposed at the end on the outflow end face 92 side become "inflow cells 82a," and the cells 82 having the plugging portion 85 disposed at the end on the inflow end face 91 side become "outflow cells 82b." Here, the honeycomb segment 86 shown in FIG. 15 has a cell structure similar to that of the plugged honeycomb structure 300 of the third embodiment shown in FIGS. 10 and 11, although it is not particularly limited thereto.

[0080] The honeycomb structure section 84 shown in Fig. 14 is preferably configured similarly to the honeycomb structure sections of the plugged honeycomb structures of the first to fourth embodiments described above. That is, in the honeycomb structure section 84, the total area of ​​the inflow cells 82a is larger than the total area of ​​the outflow cells 82b in a cross section perpendicular to the extension direction of the cells 82. The porosity of the partition walls 81 is 38% or more, and the thickness of the partition walls 81 is 125 µm or more and 280 µm or less. In addition, the honeycomb structure section 84 has a cell density of 31.0 cells / cm. 2 Furthermore, the air permeation resistance of the partition 81 is 4.5×10 7 Pa·s / m 2 For example, the porosity, thickness and air permeation resistance of the partition walls 81, and the cell density of the honeycomb structure portion 84 are preferably configured similarly to the plugged honeycomb structure 300 of the third embodiment (see Figs. 10 and 11).

[0081] The honeycomb segments 86 constituting the honeycomb structure section 84 shown in FIG. 14 may each have the same cell structure, or may each have a different cell structure.

[0082] The peripheral wall 83 in the plugged honeycomb structure 700 is preferably a peripheral coating layer formed by a peripheral coating material. The peripheral coating material is a coating material for forming a peripheral coating layer by applying it to the periphery of a joined body in which a plurality of honeycomb segments 86 are joined. In addition, it is preferable that the joined body in which a plurality of honeycomb segments 86 are joined is one in which the peripheral portion of the joined body is ground and the above-mentioned peripheral coating layer is provided.

[0083] The plugged honeycomb structure 700 configured as described above, when used as a filter for capturing PM in exhaust gas, can increase the ash capacity while suppressing an increase in soot-related pressure loss due to accumulation of PM on the surfaces of the partition walls 81, thereby achieving lower pressure loss, compared to conventional plugged honeycomb structures. EXAMPLES

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0085] Example 1 First, a clay for producing a honeycomb structure was prepared. In Example 1, a mixed powder was prepared by mixing silicon carbide (SiC) powder and metal silicon (Si) powder in a mass ratio of 80:20 as a raw material powder for preparing the clay. A binder, a pore former, and water were added to this mixed powder to prepare a molding raw material. Next, the molding raw material was kneaded to prepare a cylindrical clay. In addition, when a honeycomb structure was produced from a clay prepared using the above-mentioned materials, "SiC" is written in the "Material" column of Tables 2, 4, 6, and 8.

[0086] Next, the clay was extrusion molded using a die for producing a honeycomb molded body, to obtain a honeycomb molded body having an overall cylindrical shape.

[0087] Next, the honeycomb formed body was dried in a microwave dryer and further completely dried in a hot air dryer, after which both end faces of the honeycomb formed body were cut and adjusted to a predetermined size.

[0088] Next, plugging portions were formed on the dried honeycomb formed body. Specifically, first, a mask was applied to the inflow end face of the honeycomb formed body so that the inflow cells were covered. Then, the end of the masked honeycomb formed body was immersed in plugging slurry, and the openings of the outflow cells that were not masked were filled with the plugging slurry. Then, the openings of the inflow cells were filled with the plugging slurry on the outflow end face of the honeycomb formed body in the same manner as above. Then, the honeycomb formed body with the plugging portions formed thereon was further dried with a hot air dryer.

[0089] Next, the honeycomb formed body with the plugged portions formed thereon was degreased and fired to obtain a plugged honeycomb structure.

[0090] In the plugged honeycomb structure of Example 1, as shown in a plugged honeycomb structure 300 in Fig. 10 and Fig. 11, the shape of the cells 22 was rectangular and octagonal, and in the cross section of the honeycomb structure portion 24, the rectangular cells 22 and the octagonal cells 22 were alternately arranged with the partition wall 21 therebetween. The octagonal cells 22 were inflow cells 22a, and the rectangular cells 22 were outflow cells. 22b The column "Cell Shape" in Table 1 shows the cell shapes in the plugged honeycomb structure of Example 1. The column "Reference Figure" in Table 1 shows the numbers of drawings for referring to the cell structure (in other words, the arrangement of the inlet cells and the outlet cells) in each Example.

[0091] The plugged honeycomb structure of Example 1 had an end face diameter of 267 mm and a length in the cell extension direction of 203 mm. The partition wall had a thickness of 152 μm and a porosity of 38 %, and the cell density was 46.5 cells / cm 2 The porosity of the partition walls was a value measured by a mercury porosimeter. Moreover, the plugged honeycomb structure of Example 1 satisfied the relationship of "total number of inflow cells Na:total number of outflow cells Nb=1:1", and the cell number ratio (Na / Nb) was 1. Moreover, the average pore diameter of the partition walls was 8 μm, and the geometric surface area (GSA) of the inflow cells was 1.30 mm 2 / mm3 The results are shown in Table 1 or Table 2.

[0092] In the plugged honeycomb structure of Example 1, the total opening ratio of all cells was 81%, the total opening ratio of inflow cells was 49%, and the total opening ratio of outflow cells was 32%. "Total opening ratio of all cells" indicates the percentage of the ratio of the total opening area of ​​all cells to the cross-sectional area of ​​the honeycomb structure portion constituting the plugged honeycomb structure. Similarly, "total opening ratio of inflow cells" and "total opening ratio of outflow cells" indicate the percentage of the ratio of the total opening area of ​​inflow cells and the total opening area of ​​outflow cells to the cross-sectional area of ​​the honeycomb structure portion. The results are shown in Table 1.

[0093] For the plugged honeycomb structure of Example 1, "air permeation resistance of partition walls" was measured by the following method. The results are shown in Table 2. Furthermore, for the plugged honeycomb structure of Example 1, "pressure loss increase ΔP" was evaluated by the following method. The results are shown in Table 2.

[0094] [Air permeability resistance of partition (Pa s / m 2 )] A part of the partition wall was cut out from the honeycomb structure part of the plugged honeycomb structure. Then, air at 25°C was passed through the cut out partition wall while changing the flow rate by a mass flow meter, and the differential pressure of the air before and after passing through the partition wall was measured by a pressure gauge. Then, the unit area (mm 2 ) air permeability resistance (Pa s / m 2 ) was calculated.

[0095] [Pressure loss increase ΔP] First, the pressure loss of the plugged honeycomb structure was measured, and the measured pressure loss was defined as "initial pressure loss (kPa)". Next, the pressure loss was measured in a state where a predetermined amount of soot and ash was deposited on the partition walls of the plugged honeycomb structure, and the measured pressure loss was defined as "soot-attached pressure loss (kPa)". When measuring the soot-attached pressure loss, the amount of soot deposition was 6 g / L, and the amount of ash deposition was 30 g / L. Here, the amount of soot and ash deposition refers to the amount of soot or ash deposition (g) per unit volume (1 L) of the honeycomb structure part. Then, the value obtained by subtracting the "initial pressure loss (kPa)" from the "soot-attached pressure loss (kPa)" was defined as the "pressure loss increase ΔP (kPa)".

[0096] [Table 1]

[0097] [Table 2]

[0098] (Examples 2 to 40, Comparative Examples 1 to 22) Except for changing the configuration of each plugged honeycomb structure as shown in Tables 1 to 10, plugged honeycomb structures were produced in the same manner as in Example 1. For the plugged honeycomb structures of Examples 2 to 40 and Comparative Examples 1 to 22, "air permeation resistance of partition walls" was measured in the same manner as in Example 1. In addition, for the plugged honeycomb structures of Examples 2 to 40 and Comparative Examples 1 to 22, evaluation of "pressure loss increase ΔP" was performed in the same manner as in Example 1. The results are shown in Tables 2, 4, 6, 8 and 10.

[0099] The plugged honeycomb structure of Comparative Example 1 had a cell structure as shown in FIG. 16. FIG. 16 is an enlarged plan view of a part of the inflow end face of the plugged honeycomb structure of Comparative Example 1. As shown in FIG. 16, in the plugged honeycomb structure 500 of Comparative Example 1, the shape of the cells 42 was rectangular in the cross section of the honeycomb structure portion 44. In the plugged honeycomb structure 500 of Comparative Example 1, the inflow cells 42a and the outflow cells 42b were alternately arranged with the porous partition wall 41 between them in the cross section of the honeycomb structure portion 44. Therefore, the plugged honeycomb structure 500 of Comparative Example 1 did not have a cell structure in which one inflow cell 42a and another inflow cell 42a were adjacent to each other with the partition wall 41 between them. In FIG. 16, reference numeral 45 denotes a plugging portion, and reference numeral 51 denotes an inflow end face.

[0100] The plugged honeycomb structure of Comparative Example 16 had a cell structure as shown in FIG. 17. FIG. 17 is an enlarged plan view of a part of the inflow end face of the plugged honeycomb structure of Comparative Example 16. As shown in FIG. 17, in the plugged honeycomb structure 600 of Comparative Example 16, the shape of the cells 62 was hexagonal in the cross section of the honeycomb structure portion 64. In the plugged honeycomb structure 600 of Comparative Example 16, all the cells 62 arranged in a direction perpendicular to two opposing sides (one direction) among six sides constituting the hexagonal cells 62 were set as inflow cells 62a. All the cells 62 arranged on both sides of the inflow cells 62a arranged in one direction were set as outflow cells 62b, and further, all the cells 62 arranged on both sides of the outflow cells 62b were set as inflow cells 62a. The plugged honeycomb structure 600 of Comparative Example 16 had a cell structure in which one inflow cell 62a and another inflow cell 62a were adjacent to each other with a partition wall 61 interposed therebetween, but the total area of ​​the inflow cells 62a was the same as the total area of ​​the outflow cells 62b. In Fig. 17, reference numeral 65 denotes a plugging portion, and reference numeral 71 denotes an inflow end face.

[0101] In Examples 29 to 32, 37 to 40 and Comparative Examples 20 and 22, the following clay was prepared as a clay for producing a honeycomb structure part, and a cordierite honeycomb structure part was produced. A mixed powder of cordierite, mullite, alumina, spinel, etc. was prepared as a raw material powder for preparing the clay. A binder, a pore former, and water were added to this mixed powder to prepare a forming raw material. Next, the forming raw material was kneaded to produce a cylindrical clay. When a honeycomb structure part was produced from a clay prepared using the above-mentioned materials, "Cd" is written in the "Material" column of Table 8.

[0102] [Table 3]

[0103] [Table 4]

[0104] [Table 5]

[0105] [Table 6]

[0106] [Table 7]

[0107] [Table 8]

[0108] [Table 9]

[0109] [Table 10]

[0110] (result) The plugged honeycomb structures of Examples 1 to 3 had a significantly smaller pressure drop increase ΔP than the plugged honeycomb structure of Comparative Example 1. Moreover, the plugged honeycomb structures of Examples 1 to 3 had a smaller pressure drop increase ΔP than the plugged honeycomb structure of Comparative Example 16 in which the total opening ratio (in other words, the total area) of the inflow cells and the outflow cells was the same. Thus, the plugged honeycomb structures of Examples 1 to 3, which have a cell structure in which one inflow cell and another inflow cell are adjacent to each other with a partition wall therebetween and in which the total area of ​​the inflow cells is larger than the total area of ​​the outflow cells, had a smaller pressure drop increase ΔP.

[0111] Moreover, the plugged honeycomb structures of Examples 1 to 3 had a smaller pressure drop increase ΔP than the plugged honeycomb structure of Comparative Example 7 having the same porosity. Furthermore, the plugged honeycomb structures of Examples 1 to 3 had a smaller pressure drop increase ΔP than the plugged honeycomb structures of Comparative Examples 2 to 5 having the same partition wall thicknesses.

[0112] Similarly to the cases of Examples 1 to 3, the plugged honeycomb structures of Examples 4 to 40 also had a smaller pressure loss increase ΔP than the plugged honeycomb structures of the respective Comparative Examples for comparison.

[0113] In addition, the permeation resistance (Pa s / m 2 In order to compare the effect of "air permeation resistance of partition walls (Pa s / m"), examples and comparative examples in which the partition wall thickness is 203 μm are extracted, and the results are shown in Tables 9 and 10. Tables 9 and 10 show the results of Examples 9, 18, 23, 27, 31, 35 and 39, and Comparative Examples 11 and 23. In addition, the "air permeation resistance of partition walls (Pa s / m") in Table 10 2 The relationship between the permeation resistance (Pa s / m 218 is a graph showing the relationship between the pressure drop increase ΔP (kPa) and the permeation resistance (Pa s / m 2 ) and the vertical axis indicates the pressure drop increase ΔP (kPa). As shown in Table 10 and Figure 18, the air permeation resistance of the partition is 4.5×10 7 Pa·s / m 2 It was found that the rate of change in pressure drop increase ΔP (kPa) was large within the following range, and the plugged honeycomb structures of Examples 9, 18, 23, 27, 31, 35 and 39 were expected to further suppress the pressure drop increase ΔP. [Industrial Applicability]

[0114] The plugged honeycomb structure of the present invention can be used as a filter for purifying exhaust gas. [Explanation of symbols]

[0115] 1, 21, 41, 61, 81: partition wall, 2, 22, 42, 62, 82: cell, 2a, 22a, 42a, 62a, 82a: inlet cell, 2b, 22b, 42b, 62b, 82b: outlet cell, 3, 83: outer peripheral wall, 4, 24, 44, 64, 84: honeycomb structure portion, 5, 25, 45, 65, 85: plugging portion, 11, 31, 51, 71, 91: inlet end face, 12, 32, 92: outlet end face, 86: honeycomb segment, 87: bonding layer, 88: segment outer wall, 100, 200, 300, 400, 500, 600, 700: plugged honeycomb structure, T, T1, T2: thickness of partition wall.

Claims

1. a honeycomb structure having porous partition walls arranged to surround a plurality of cells that serve as fluid flow paths extending from an inflow end face to an outflow end face; and a plugging portion arranged to plug either one of the inlet end face side or the outlet end face side of the cell, the plugging portion is disposed at an end portion on the outflow end face side, and the cell having an opening on the inflow end face side is defined as an inflow cell, and the plugging portion is disposed at an end portion on the inflow end face side, and the cell having an opening on the outflow end face side is defined as an outflow cell, In a cross section of the honeycomb structure section perpendicular to the cell extension direction, the shape of the cells is polygonal, and one of the inlet cells and another of the inlet cells are adjacent to each other with the partition wall therebetween, and In the cross section perpendicular to the extension direction of the cells, the total area of ​​the inflow cells is larger than the total area of ​​the outflow cells, The porosity of the partition wall is 38% or more, the thickness of the partition wall is 125 μm or more and 280 μm or less, and the cell density of the honeycomb structure portion is 31.0 cells / cm or more, The air permeation resistance of the partition is 4.5 × 10 Pa s / m or less, when the partition wall disposed between the inflow cell and the outflow cell is defined as a first partition wall and the partition wall disposed between the inflow cells is defined as a second partition wall, a thickness of the first partition wall and a thickness of the second partition wall are the same, A plugged honeycomb structure, wherein at least one catalyst selected from the group consisting of an oxidation catalyst, a selective catalytic reduction catalyst, and a three-way catalyst is supported on the partition walls.

2. The plugged honeycomb structure according to claim 1, wherein the partition walls have an air permeation resistance of 4.0×10 7 Pa·s / m 2 or less.

3. In the cross section perpendicular to the extension direction of the cells, the shape of one of the inlet cells and the shape of one of the outlet cells are congruent or similar, and 3. The plugged honeycomb structure according to claim 1, wherein a ratio of a total number Na of said inlet cells to a total number Nb of said outlet cells is 2 or more.

4. The plugged honeycomb structure according to any one of claims 1 to 3, wherein the inlet cells have one type of shape in the cross section perpendicular to the cell extension direction.

5. The plugged honeycomb structure according to any one of claims 1 to 4, wherein in the cross section perpendicular to the cell extension direction, the inlet cells and the outlet cells each have a hexagonal shape.

6. The plugged honeycomb structure according to any one of claims 1 to 5, wherein at least one of the cells has a shape of a regular hexagon in the cross section perpendicular to the extending direction of the cells.

7. 2. The plugged honeycomb structure according to claim 1, wherein the oxidation catalyst is supported on the partition walls in an amount of 0.1 to 30 g / L.

8. 2. The plugged honeycomb structure according to claim 1, wherein the selective catalytic reduction catalyst is supported on the partition walls, and the supported amount of the selective catalytic reduction catalyst is 50 to 130 g / L.

9. 9. The plugged honeycomb structure according to claim 1, wherein the selective catalytic reduction catalyst is a zeolite type selective catalytic reduction catalyst or a vanadium type selective catalytic reduction catalyst.

10. The plugged honeycomb structure according to claim 1, wherein the partition walls support the three-way catalyst, and the supported amount of the three-way catalyst is 40 to 130 g / L.

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