Honeycomb structure

Abstract

The utility model provides a honeycomb structural body which can meet all the following required characteristics: the honeycomb structural body has practical heat capacity, can maintain the maintenance cost to be low, and is easy to detect the maintenance time based on the PM accumulation amount by using a pressure sensor. A columnar honeycomb structure provided with an outer peripheral side wall, a plurality of introduction cells, and a plurality of discharge cells, characterized in that: at least some of the plurality of introduction cells are adjacent to at least some of the plurality of discharge cells with a partition wall therebetween; the cell density based on the total number of the plurality of introduction cells and the plurality of discharge cells is 29-43 cells / cm2, the average thickness of the partition walls is 0.173 mm or more and 0.236 mm or less, and Dout represents the average value of the opening diameters of the discharge cells other than the discharge cells adjacent to the outer peripheral side wall among the plurality of discharge cells, and Dout represents the average value of the opening diameters of the discharge cells other than the discharge cells adjacent to the outer peripheral side wall. When Din is the average value of the opening diameters of the plurality of introduction cells other than the introduction cells adjacent to the outer peripheral side wall, 1.20 < = Din / Dout < = 1.38 is satisfied.

Description

Technical Field

[0001] This utility model relates to a honeycomb structure. Background Technology

[0002] Diesel engines offer better thermal efficiency than gasoline engines, but they produce particulate matter (PM) such as soot and ash due to diffusion combustion. These particulate matter are confirmed to be carcinogenic, therefore their release into the atmosphere must be prevented. Consequently, in addition to the previous weight-based quantitative limits centered in Europe, strict limits on PM number are now imposed.

[0003] However, there are limits to reducing PM emissions by improving combustion; therefore, installing a filter called a DPF (Diesel Particulate Filter) in the exhaust gas is currently the only effective means. As such, wall-flow filters, designed so that exhaust gas passes through porous partitions, are effective. Specifically, wall-flow filters have multiple inlet compartments and multiple outlet compartments adjacent to each other separated by porous partitions, and are constructed from a honeycomb structure capable of capturing PM during the passage of exhaust gas through the partitions.

[0004] Wall-flow filters with honeycomb structures suffer from increased pressure loss due to PM accumulation within the filter over time. Therefore, such filters inject additional fuel to raise the exhaust gas temperature and ignite the soot (filter regeneration) for each constant PM accumulation, thereby reducing pressure loss. Furthermore, since ash does not burn at high temperatures, trucks and off-road vehicles, which travel longer distances than passenger cars (i.e., longer filter operating times), require periodic cleaning of the honeycomb structure to remove accumulated ash and reduce pressure loss. If the pressure loss immediately increases upon PM accumulation, the frequency of filter regeneration and cleaning increases, leading to higher fuel consumption and maintenance costs. Therefore, research has been conducted on reducing pressure loss during PM accumulation by studying the arrangement and size of the inlet and outlet compartments (Patent Document 1, Patent Document 2).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2019 / 104057

[0008] Patent Document 2: International Publication No. 2013 / 187444 Utility Model Content

[0009] The problem to be solved by the utility model

[0010] Traditionally, the timing of filter regeneration and cleaning was determined by measuring the pressure loss between the filter inlet and outlet using pressure sensors. However, if a large amount of PM accumulates after the filter and the pressure loss remains low, predicting the amount of PM buildup based on pressure loss becomes difficult when using pressure sensors for filter regeneration control, leading to PM over-accumulation and potential filter damage. Therefore, it is desirable to reduce the frequency of filter regeneration and cleaning by preventing the pressure loss after PM accumulation from becoming excessively high, thereby reducing maintenance costs. Simultaneously, by increasing the change in pressure loss based on the amount of accumulated PM (pressure loss tilt), it is easier to use pressure sensors to detect the appropriate amount of PM buildup for filter regeneration and cleaning. Furthermore, for cellular structures, it is also necessary to ensure sufficient heat capacity to prevent excessive temperature rise and damage during filter regeneration.

[0011] This invention was made in view of the above circumstances. In one embodiment, the objective is to provide a honeycomb structure that can meet all of the following requirements: having practical heat capacity, being able to keep maintenance costs low, and being able to easily detect the period requiring maintenance based on PM accumulation using a pressure sensor.

[0012] Solution for solving the problem

[0013] In order to solve the above-mentioned problems, the inventors of this utility model conducted in-depth research and found that appropriately combining parameters related to honeycomb structures, such as cell density, average thickness of partition walls, opening diameter ratio, and average porosity of partition walls, is effective in solving the problems, thus completing the utility model illustrated below.

[0014] [Option 1]

[0015] A columnar honeycomb structure comprising: an outer peripheral sidewall; a plurality of inlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having an opening at the inlet end face and a sealing portion at the outlet end face; and a plurality of outlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having a sealing portion at the inlet end face and an opening at the outlet end face, characterized in that...

[0016] At least a portion of the inlet compartments and at least a portion of the outlet compartments are adjacent to each other across a partition wall.

[0017] The compartment density, based on the total number of the plurality of inlet compartments and the plurality of outlet compartments, is 29–43 compartments / cm². 2 ,

[0018] The average thickness of the partition wall is greater than 0.173 mm and less than 0.236 mm.

[0019] Let D be the average opening diameter of the discharge compartments excluding those adjacent to the outer peripheral sidewall. out Let D be the average opening diameter of the multiple inlet compartments excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then 1.20 ≤ D is satisfied. in / D out ≤1.38.

[0020] [Option 2]

[0021] The honeycomb structure according to Scheme 1 is characterized in that,

[0022] Apart from the inlet compartments adjacent to the outer peripheral sidewalls, the average opening diameter D of each of the plurality of inlet compartments is... in For thicknesses between 1.48mm and 1.80mm,

[0023] Except for the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out It is between 1.16mm and 1.48mm.

[0024] [Option 3]

[0025] The honeycomb structure according to scheme 1 or 2 is characterized in that,

[0026] The average porosity of the partition wall is 52-60%.

[0027] [Option 4]

[0028] The honeycomb structure according to scheme 1 or 2 is characterized in that,

[0029] The density, measured based on the external dimensions, is 0.288–0.410 g / cm³. 3 .

[0030] [Option 5]

[0031] The honeycomb structure according to scheme 1 or 2 is characterized in that,

[0032] The ratio of the number of inlet compartments (excluding those adjacent to the outer peripheral sidewall) to the number of outlet compartments (excluding those adjacent to the outer peripheral sidewall) is 0.9 to 1.1.

[0033] [Option 6]

[0034] The honeycomb structure according to scheme 1 or 2 is characterized in that,

[0035] If the mass of particulate matter containing soot per unit volume of the honeycomb structure is 1 g / L, then the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P1.

[0036] When the mass of particulate matter containing soot per unit volume of the honeycomb structure is 3 g / L, the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P2.

[0037] Then it satisfies 45% ≤ (P2-P1) / P1.

[0038] [Option 7]

[0039] The honeycomb structure according to scheme 1 or 2 is characterized in that,

[0040] The partition wall contains cordierite.

[0041] [Option 8]

[0042] A columnar honeycomb structure comprising: an outer peripheral sidewall; a plurality of inlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having an opening at the inlet end face and a sealing portion at the outlet end face; and a plurality of outlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having a sealing portion at the inlet end face and an opening at the outlet end face, characterized in that...

[0043] At least a portion of the inlet compartments and at least a portion of the outlet compartments are adjacent to each other across a partition wall.

[0044] The compartment density, based on the total number of the plurality of inlet compartments and the plurality of outlet compartments, is 29–36 compartments / cm². 2 ,

[0045] The average thickness of the partition wall is greater than 0.231 mm and less than 0.312 mm.

[0046] Let D be the average opening diameter of the discharge compartments excluding those adjacent to the outer peripheral sidewall. out Let D be the average opening diameter of the multiple inlet compartments excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then 1.14 ≤ D in / D out ≤1.37,

[0047] The average porosity of the partition wall is 57-63%.

[0048] [Option 9]

[0049] The honeycomb structure according to Scheme 8 is characterized in that,

[0050] Apart from the inlet compartments adjacent to the outer peripheral sidewalls, the average opening diameter D of each of the plurality of inlet compartments is... in For thicknesses between 1.52mm and 1.76mm,

[0051] Except for the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out It is between 1.20mm and 1.44mm.

[0052] [Option 10]

[0053] The honeycomb structure according to scheme 8 or 9 is characterized in that,

[0054] The average pore size of the partition wall is 7–13 μm.

[0055] [Option 11]

[0056] The honeycomb structure according to scheme 8 or 9 is characterized in that,

[0057] The density, measured based on the external dimensions, is 0.288–0.410 g / cm³. 3 .

[0058] [Option 12]

[0059] The honeycomb structure according to scheme 8 or 9 is characterized in that,

[0060] The ratio of the number of inlet compartments (excluding those adjacent to the outer peripheral sidewall) to the number of outlet compartments (excluding those adjacent to the outer peripheral sidewall) is 0.9 to 1.1.

[0061] [Option 13]

[0062] The honeycomb structure according to scheme 8 or 9 is characterized in that,

[0063] If the mass of particulate matter containing soot per unit volume of the honeycomb structure is 1 g / L, then the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P1.

[0064] When the mass of particulate matter containing soot per unit volume of the honeycomb structure is 3 g / L, the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P2.

[0065] Then it satisfies 45% ≤ (P2-P1) / P1.

[0066] [Option 14]

[0067] The honeycomb structure according to scheme 8 or 9 is characterized in that,

[0068] The partition wall contains cordierite.

[0069] Utility Model Effect

[0070] By using the honeycomb structure according to one embodiment of this invention as an exhaust gas filter, the pressure loss after PM accumulation is prevented from becoming excessively large, thereby reducing the frequency of filter regeneration and cleaning. Simultaneously, by increasing the change in pressure loss based on the amount of accumulated PM (pressure loss tilt), the amount of PM accumulation suitable for filter regeneration and cleaning can be easily detected using a pressure sensor. Thus, a filter can be obtained that maintains low maintenance costs and allows for easy detection of maintenance needs based on PM accumulation using a pressure sensor. Therefore, the possibility of filter damage due to excessive PM accumulation can be reduced. Furthermore, the honeycomb structure according to one embodiment of this invention has a practical heat capacity, thus reducing the risk of damage due to excessive temperature rise during filter regeneration. Therefore, according to one embodiment of this invention, a honeycomb structure with extremely superior practicality can be provided. Attached Figure Description

[0071] Figure 1 It is a schematic three-dimensional representation of a wall-flow honeycomb structure.

[0072] Figure 2 This is a schematic cross-sectional view of the honeycomb structure with wall flow pattern when viewed from a section parallel to the direction of the compartment extension.

[0073] Figure 3 This is a schematic, enlarged view of the partition wall of a honeycomb structure when viewed from a cross-section orthogonal to the direction in which the compartment extends.

[0074] Figure 4 This is an illustrative diagram schematically illustrating an example of a method for forming a sealing section based on a scraper. Detailed Implementation

[0075] Next, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the present invention is not limited to the following embodiments, and design changes and improvements may be appropriately made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0076] (1. Honeycomb structure)

[0077] (1-1) Basic Structure

[0078] exist Figure 1 as well as Figure 2 The diagram illustrates a schematic perspective view and a cross-sectional view of a cylindrical honeycomb structure 100 that can be used as a wall-flow type automotive exhaust filter. The honeycomb structure 100 includes: an outer peripheral sidewall 102; a plurality of inlet chambers 108 disposed on the inner peripheral side of the outer peripheral sidewall 102, extending parallel to an inlet end face 104 to an outlet end face 106, having an opening 107 on the inlet end face 104 and a sealing portion 109 on the outlet end face 106; and a plurality of outlet chambers 110 disposed on the inner peripheral side of the outer peripheral sidewall 102, extending parallel to an inlet end face 104 to an outlet end face 106, having a sealing portion 109 on the inlet end face 104 and an opening 107 on the outlet end face 106.

[0079] In this honeycomb structure 100, at least a portion of the inlet chambers 108 and at least a portion of the outlet chambers 110 are adjacent to each other across a partition wall 112. When the inlet chambers 108 and outlet chambers 110 are adjacent across the partition wall 112, the surface of the partition wall 112 facilitates filtration. For example, if exhaust gas containing particulate matter such as soot is supplied to the upstream inlet end face 104 of the honeycomb structure 100, the exhaust gas is introduced into the inlet chamber 108 and proceeds downstream within the inlet chamber 108. The downstream outlet end face 106 of the inlet chamber 108 is sealed, so the exhaust gas flows into the outlet chamber 110 through the partition wall located between the adjacent inlet chambers 108 and outlet chambers 110. Particulate matter cannot pass through the partition wall 112 and is therefore captured and accumulated within the inlet chamber 108. After the particulate matter is removed, the clean exhaust gas flowing into the discharge compartment 110 moves downstream within the discharge compartment 110 and flows out from the outlet end face 106 on the downstream side.

[0080] In a preferred embodiment, at least one of the plurality of discharge compartments 110 is adjacent only to the inlet compartment 108 (i.e., not adjacent to either the discharge compartment 110 or the outer peripheral sidewall 102). This is because the discharge compartment 110 performs a filtering function by being adjacent to the inlet compartment 108. Furthermore, it is preferable that none of the plurality of discharge compartments 110 are adjacent to each other.

[0081] There is no limitation on the end face shape of the honeycomb structure 100. For example, it can be a circular shape such as a circular, elliptical, racetrack, or oblong shape, a polygonal shape such as a triangular or quadrilateral shape, or other irregular shapes. The end face shape of the illustrated honeycomb structure 100 is circular, and the whole is cylindrical.

[0082] There is no particular limitation on the height of the honeycomb structure (the length from the inlet end face to the outlet end face), and it can be appropriately set according to the use and required performance. The height of the honeycomb structure can be set, for example, to 40 to 450 mm, preferably 60 to 400 mm, and more preferably 100 to 330 mm. There is no particular limitation on the relationship between the height of the honeycomb structure and the maximum diameter of each end face (which refers to the maximum length among the diameters passing through the centers of gravity of each end face of the honeycomb structure). Therefore, the height of the honeycomb structure can be longer than the maximum diameter of each end face, and the height of the honeycomb structure can also be shorter than the maximum diameter of each end face.

[0083] There is no particular limitation on the opening shape of the introduction compartment. For example, in a cross-section orthogonal to the direction in which the compartment extends in the honeycomb structure, it can be a polygon (quadrilateral (rectangle, square), pentagon, hexagon, heptagon, octagon, etc.), a circular shape (circle, ellipse, long ellipse, oval, oblong, etc.), or the like. These shapes can be single, or two or more can be combined. Among them, for the reason of reducing pressure loss, except for the compartments adjacent to the outer peripheral side wall, the opening shapes of the plurality of introduction compartments are preferably all hexagons or octagons, and more preferably octagons. When the opening shapes of the introduction compartment and the discharge compartment are polygons, the corners can be chamfered with an R. In addition, in this specification, even if chamfered with an R, it is treated as a polygon.

[0084] There is no particular limitation on the opening shape of the discharge compartment, and it can be set according to the opening shape of the introduction compartment. For example, when the opening shape of the introduction compartment is an octagon, it is preferably a quadrilateral.

[0085] (1-2) Specific structure

[0086] The present inventor has found appropriate combinations of parameters related to the specific structure of the honeycomb structure, such as the density of the two compartments, the average thickness of the partition walls, the opening diameter ratio, and the average porosity of the partition walls. Therefore, they are separately described as the first embodiment and the second embodiment.

[0087] The present inventor has found appropriate combinations of parameters related to the specific structure of the honeycomb structure, such as the density of the two compartments, the average thickness of the partition walls, the opening diameter ratio, and the average porosity of the partition walls. Therefore, they are separately described as the first embodiment and the second embodiment. <A. First embodiment>

[0088] (A1) Compartment density

[0089] The compartment density is an indicator of the number of compartments per unit area when viewed from the inlet or outlet end face of the honeycomb structure. From the perspective of improving pressure loss gradient, a compartment density lower than that conventionally used for DPF is preferred. However, simply reducing the compartment density decreases the heat capacity of the honeycomb structure, making it prone to high temperatures during filter regeneration, potentially leading to damage. Therefore, the soot accumulation limit decreases, and excessive reduction in compartment density is undesirable. Therefore, the compartment density, based on the total number of inlet compartments 108 and outlet compartments 110, is preferably 29 to 43 compartments / cm². 2 More preferably, it is 30-40 compartments / cm². 2 More preferably, it is 31–39 compartments / cm 2 The compartment density is calculated by dividing the total number of multiple inlet compartments 108 and multiple outlet compartments 110 (including the compartments with sealed openings, the outlet compartments 110 adjacent to the outer peripheral sidewall 102, and the inlet compartments 108 adjacent to the outer peripheral sidewall 102) by the area of ​​one end face of the honeycomb structure 100 other than the outer peripheral sidewall 102.

[0090] (A2) Average thickness of the partition wall

[0091] From the viewpoint of satisfying the above-mentioned compartment density, ensuring the strength of the honeycomb structure, and ensuring the heat capacity of the honeycomb structure to increase the limit of soot accumulation, the average thickness of the partition 112 is preferably 0.173 mm or more and 0.236 mm or less, more preferably 0.198 mm or more and 0.229 mm or less, and even more preferably 0.203 mm or more and 0.216 mm or less. Figure 3 The diagram shows a schematic, partially enlarged view of the partition wall 112 of a honeycomb structure 100, with an octagonal opening for the intake compartment 108 and a quadrilateral opening for the exhaust compartment 110, viewed in a cross-section orthogonal to the direction of compartment extension. The thickness of partition wall 112 refers to the length D of the line segment connecting the centroids O of adjacent compartments in a cross-section orthogonal to the direction of compartment extension (the height direction of the honeycomb structure), which traverses the partition wall. The average thickness of partition wall 112 is calculated based on the thickness of all partition walls 112.

[0092] Furthermore, "two compartments sandwiched by a partition wall and adjacent" means that when the partition wall of the honeycomb structure is viewed from a cross section orthogonal to the direction in which the compartment extends, the two compartments are adjacent by sandwiching the opposite wall surface of one partition wall (the edge of the polygon dividing the compartment), excluding the case where the vertices of the polygon dividing the two compartments are adjacent to each other.

[0093] (A3) Opening diameter ratio (D) in / D out )

[0094] From the perspective of increasing the pressure loss slope and minimizing the pressure loss after PM accumulation, if we define the average opening diameter of the discharge compartments (excluding those adjacent to the outer peripheral sidewalls) as D... out Let D be the average opening diameter of the multiple inlet compartments, excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then, it is preferable to satisfy 1.20≤D in / D out ≤1.38, more preferably satisfying 1.22≤D in / D out ≤1.29, further optimization satisfies 1.25≤D in / D out ≤1.28.

[0095] The opening diameter of each of the multiple inlet compartments is defined as the equivalent circle diameter calculated based on the opening area of ​​that inlet compartment. D is the average value. in It is calculated based on the opening diameter of all inlet compartments except those adjacent to the outer peripheral sidewall.

[0096] The opening diameter of each of the multiple discharge compartments is defined as the equivalent circle diameter calculated based on the opening area of ​​that discharge compartment. Average value D out It is calculated based on the opening diameter of all discharge compartments except those adjacent to the outer peripheral sidewall.

[0097] (A4) Opening diameter

[0098] From the perspective of suppressing initial pressure loss and preventing excessive pressure loss due to PM accumulation, the average opening diameter D of each of the multiple inlet compartments, excluding the inlet compartment adjacent to the outer peripheral sidewall, is... in Preferably, the diameter is 1.48–1.80 mm, more preferably 1.50–1.79 mm, and even more preferably 1.54–1.75 mm. Furthermore, excluding the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out The preferred thickness is 1.16–1.48 mm, more preferably 1.18–1.43 mm, and even more preferably 1.22–1.39 mm.

[0099] (A5) Average porosity of the partition wall

[0100] From the viewpoint of reducing pressure loss, the lower limit of the average porosity of the partition walls is preferably 52% or more, more preferably 53% or more. Further, from the viewpoint of improving the mechanical strength of the honeycomb structure, the upper limit of the average porosity of the partition walls is preferably 60% or less, more preferably 58% or less. Therefore, for example, the average porosity of the partition walls is preferably 52 to 60%, more preferably 53 to 58%. In the present specification, the porosity of the partition walls is measured by the mercury intrusion method defined in JIS R1655:2003 (Japanese Industrial Standards). Further, regarding the average porosity, the average value obtained by collecting samples of the partition walls (0.3 g each) without bias from six locations of the honeycomb structure and determining the porosity of each is used as the measured value.

[0101] (A6) Ratio of the number of inlet compartments to the number of outlet compartments

[0102] From the viewpoint of suppressing an increase in pressure loss and increasing the pressure loss gradient, the ratio of the number of the plurality of inlet compartments to the number of the plurality of outlet compartments is preferably 0.9 to 1.1, more preferably 0.95 to 1.05, still more preferably 0.99 to 1.01, and most preferably 1. Further, when calculating the ratio of the number of inlet compartments to the number of outlet compartments, the outlet compartments adjacent to the outer peripheral side wall and the inlet compartments adjacent to the outer peripheral side wall are not counted.

[0103] <B. Second Embodiment>

[0104] (B1) Compartment density

[0105] The compartment density is an index indicating the number of compartments per unit area when observing the honeycomb structure from the inlet end face or the outlet end face. From the aspect of increasing the pressure loss gradient, it is preferable that the compartment density is smaller than the value conventionally used for DPF. However, when only the compartment density is decreased, the heat capacity of the honeycomb structure is reduced, and it tends to become high temperature during filter regeneration, and the honeycomb structure may be damaged. Therefore, the maximum soot accumulation amount is reduced, and thus it is not desirable to excessively decrease the compartment density. Therefore, the compartment density based on the total number of the plurality of inlet compartments 108 and the plurality of outlet compartments 110 is preferably 29 to 36 compartments / cm 2 , more preferably 30 to 34 compartments / cm 2 , still more preferably 31 to 33 compartments / cm 2 . The compartment density is calculated by dividing the total number of the plurality of inlet compartments 108 and the plurality of outlet compartments 110 (including the sealed compartments, the outlet compartments 110 adjacent to the outer peripheral side wall 102, and the inlet compartments 108 adjacent to the outer peripheral side wall 102) by the area of one end face of the honeycomb structure 100 excluding the outer peripheral side wall 102.

[0106] (B2) Average thickness of partition walls

[0107] From the viewpoint of satisfying the above-mentioned compartment density, ensuring the strength of the honeycomb structure, and ensuring the heat capacity of the honeycomb structure to increase the limit of soot accumulation, the average thickness of the partition 112 is preferably 0.231 mm or more and 0.312 mm or less, more preferably 0.241 mm or more and 0.292 mm or less, and even more preferably 0.254 mm or more and 0.279 mm or less. Figure 3 The diagram shows a schematic, partially enlarged view of the partition wall 112 of a honeycomb structure 100, with an octagonal opening for the intake compartment 108 and a quadrilateral opening for the exhaust compartment 110, viewed in a cross-section orthogonal to the direction of compartment extension. The thickness of partition wall 112 refers to the length D of the line segment connecting the centroids O of adjacent compartments in a cross-section orthogonal to the direction of compartment extension (the height direction of the honeycomb structure), which traverses the partition wall. The average thickness of partition wall 112 is calculated based on the thickness of all partition walls 112.

[0108] Furthermore, "two compartments sandwiched by a partition wall and adjacent" means that when the partition wall of the honeycomb structure is viewed from a cross section orthogonal to the direction in which the compartment extends, the two compartments are adjacent by sandwiching the opposite wall surface of one partition wall (the edge of the polygon dividing the compartment), excluding the case where the vertices of the polygon dividing the two compartments are adjacent to each other.

[0109] (B3) Opening diameter ratio (D) in / D out )

[0110] From the perspective of increasing the pressure loss slope and minimizing the pressure loss after PM accumulation, if we define the average opening diameter of the discharge compartments (excluding those adjacent to the outer peripheral sidewalls) as D... out Let D be the average opening diameter of the multiple inlet compartments, excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then, it is preferable to satisfy 1.14≤D in / D out ≤1.37, more preferably satisfying 1.22≤D in / D out ≤1.27, further optimization satisfies 1.23≤D in / D out ≤1.24.

[0111] The opening diameter of each of the multiple inlet compartments is defined as the equivalent circle diameter calculated based on the opening area of ​​that inlet compartment. D is the average value. in It is calculated based on the opening diameter of all inlet compartments except those adjacent to the outer peripheral sidewall.

[0112] The opening diameter of each of the multiple discharge compartments is defined as the equivalent circle diameter calculated based on the opening area of ​​that discharge compartment. D is the average value. out It is calculated based on the opening diameter of all discharge compartments except those adjacent to the outer peripheral sidewall.

[0113] (B4) Opening diameter

[0114] From the perspective of suppressing initial pressure loss and preventing excessive pressure loss due to PM accumulation, the average opening diameter D of each of the multiple inlet compartments, excluding the inlet compartment adjacent to the outer peripheral sidewall, is... in Preferably, the diameter is 1.52–1.76 mm, more preferably 1.63–1.73 mm, and even more preferably 1.64–1.69 mm. Furthermore, excluding the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out The preferred thickness is 1.20–1.44 mm, more preferably 1.31–1.43 mm, and even more preferably 1.35–1.41 mm.

[0115] (B5) Average porosity of the partition wall

[0116] From the viewpoint of reducing pressure loss, the lower limit of the average porosity of the partition wall is preferably 57% or more, more preferably 58% or more. Furthermore, from the viewpoint of improving the mechanical strength of the honeycomb structure, the upper limit of the average porosity of the partition wall is preferably 63% or less, more preferably 61% or less. Therefore, for example, the average porosity of the partition wall is preferably 57-63%, more preferably 58-61%. In this specification, the porosity of the partition wall is measured by the mercury intrusion porosimetry method as specified in JIS R1655:2003. Furthermore, regarding the average porosity, the average value is obtained by collecting partition wall samples (0.3 g each) from six locations of the honeycomb structure without deviation and calculating the porosity of each sample.

[0117] (B6) Ratio of the number of inlet compartments to the number of outlet compartments

[0118] From the viewpoint of suppressing pressure loss rise and increasing pressure loss tilt, the ratio of the number of multiple inlet compartments to the number of multiple outlet compartments is preferably 0.9 to 1.1, more preferably 0.95 to 1.05, even more preferably 0.99 to 1.01, and most preferably 1. Furthermore, when calculating the ratio of the number of inlet compartments to the number of outlet compartments, outlet compartments adjacent to the outer peripheral sidewall and inlet compartments adjacent to the outer peripheral sidewall are not counted.

[0119] (B7) Average pore size

[0120] From the viewpoint of pressure loss due to soot accumulation, the average pore size of the partition wall 112 is preferably 13 μm or less, more preferably 11 μm or less. Furthermore, from the viewpoint of pressure loss without soot accumulation, the average pore size of the partition wall 112 is preferably 7 μm or more, more preferably 9 μm or more. Therefore, the average pore size of the partition wall 112 is preferably, for example, 7 to 13 μm, more preferably 9 to 11 μm. The average pore size of the partition wall is measured by mercury porosimetry according to JIS R1655:2003. Twenty test pieces of partition walls, including the central and peripheral portions of the honeycomb structure, are uniformly collected, and their average pore size is measured. The average value of these samples is taken as the average pore size of the entire honeycomb structure.

[0121] (1-3) Density

[0122] From the perspective of increasing the limit of soot accumulation by suppressing the temperature rise during filter regeneration, the honeycomb structure preferably has a high mass per unit volume, i.e., a high density. Since a high density results in a higher heat capacity, it can suppress temperature rise. The density mentioned here is a value calculated based on the volume measured from the external dimensions of the honeycomb structure, without considering the internal compartment structure and pores. Specifically, the lower limit of the density of the honeycomb structure is preferably 0.288 g / cm³. 3 The above, more preferably 0.291 g / cm³ 3 The above is further optimized to 0.294 g / cm³. 3 The above describes the upper limit of the density of the honeycomb structure. However, considering the ease of manufacturing the aforementioned compartment structure and materials, a density of 0.410 g / cm³ is preferred. 3 The preferred value is 0.382 g / cm³. 3 The following is a further preferred value: 0.381 g / cm³ 3 Therefore, for example, the density of the honeycomb structure is preferably 0.288 to 0.410 g / cm³. 3 More preferably, it is 0.291–0.382 g / cm³. 3 More preferably, it is 0.294–0.381 g / cm³. 3 .

[0123] (1-4) Pressure loss tilt

[0124] If the pressure loss variation (pressure loss tilt) based on the amount of PM accumulated in the cellular structure is large, it is easy to use a pressure sensor to detect the amount of PM accumulation suitable for filter regeneration and cleaning.

[0125] Specifically, when the mass of particulate matter containing soot per unit volume of the honeycomb structure is 1 g / L, the pressure loss of exhaust gas at a temperature of 250℃ and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P1.

[0126] When the mass of particulate matter containing soot per unit volume of the honeycomb structure is 3 g / L, the pressure loss of exhaust gas at a temperature of 250℃ and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P2.

[0127] Preferably, 45% ≤ (P2-P1) / P1 is satisfied, more preferably 47% ≤ (P2-P1) / P1 is satisfied, and even more preferably 48% ≤ (P2-P1) / P1 is satisfied.

[0128] Furthermore, from the viewpoint of ensuring the practicality of the filter by suppressing excessive pressure loss, it is preferable to satisfy (P2-P1) / P1≤66%, more preferably to satisfy (P2-P1) / P1≤63%, and even more preferably to satisfy (P2-P1) / P1≤61%.

[0129] Therefore, for example, the pressure loss tilt of the cellular structure preferably satisfies 45% ≤ (P2-P1) / P1 ≤ 66%, more preferably 47% ≤ (P2-P1) / P1 ≤ 63%, and even more preferably 48% ≤ (P2-P1) / P1 ≤ 61%.

[0130] From the viewpoint of ensuring the practicality of the filter by suppressing excessive pressure loss rise, the upper limit of P2 is preferably 3.69 kPa or less, more preferably 3.67 kPa or less, and even more preferably 3.65 kPa or less. From the viewpoint of improving the pressure loss slope, the lower limit of P2 is preferably 3.21 kPa or more, more preferably 3.49 kPa or more, and even more preferably 3.57 kPa or more.

[0131] (1-5) Material

[0132] From the viewpoint of obtaining excellent thermal shock resistance, the honeycomb structure contains at least one or more of the following: the partition wall, preferably the outer peripheral sidewall, the partition wall, more preferably the outer peripheral sidewall, the partition wall, and the sealing portion: cordierite, silicon carbide, silicon-silicon carbide composite material, silicon nitride, mullite, alumina, and aluminum titanate.

[0133] The outer peripheral walls, partitions, and sealing portions of the honeycomb structure may also contain ceramics other than those mentioned above. Examples of other ceramics include zirconium phosphate, cordierite-silicon carbide composites, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, titanium dioxide, and cerium oxide. Furthermore, these other ceramics may be contained individually or in combination with more than one type.

[0134] When the honeycomb structure is mainly composed of cordierite, the lower limit of the cordierite content in the septa, preferably the outer peripheral sidewalls, and the septa, more preferably the outer peripheral sidewalls, septa, and sealing portions of the honeycomb structure is preferably 90% by mass or more, more preferably 91% by mass or more, and even more preferably 92% by mass or more. The upper limit is not specifically set, but from the viewpoint of changing the characteristics of the honeycomb structure by adding other ceramics, the upper limit of the cordierite content in the septa, preferably the outer peripheral sidewalls, and the septa, more preferably the outer peripheral sidewalls, septa, and sealing portions of the honeycomb structure is preferably 96% by mass or less, more preferably 95% by mass or less, and even more preferably 94% by mass or less. Therefore, when the honeycomb structure is mainly composed of cordierite, the cordierite content in the septa, preferably the outer peripheral sidewalls, and the septa, more preferably the outer peripheral sidewalls, septa, and sealing portions of the honeycomb structure is preferably 90 to 96% by mass, more preferably 91 to 95% by mass, and even more preferably 92 to 94% by mass.

[0135] The cordierite content can be measured by X-ray diffraction. Specifically, using an X-ray diffraction apparatus that utilizes the Kα rays of Cu (e.g., the X'pert PRO apparatus manufactured by Malvern Panalytical), samples from the outer sidewalls, septa, or sealing portions are analyzed by X-ray diffraction in the range of 2θ = 8–100°. The analysis is performed using the Rietveld analytical program RIETAN, thereby measuring the cordierite crystallization ratio, which is taken as the cordierite content.

[0136] A honeycomb structure can be a honeycomb composite having multiple honeycomb sheets and a bonding layer that joins the outer peripheral surfaces of the honeycomb sheets together. By using a honeycomb composite, the total cross-sectional area of ​​the compartments, which is important for ensuring airflow, can be increased while suppressing crack formation. The bonding layer can be formed using a bonding material. There are no particular limitations on the bonding material; a paste-like material made by adding a solvent such as water to a ceramic material can be used. The bonding material may also contain the same material as the partition walls. In addition to joining the honeycomb sheets together, the bonding material can also be used as a coating material for the outer periphery of the joined honeycomb sheets.

[0137] In one embodiment, the average depth of the sealing portion on both the inlet and outlet end faces is 2 to 8 mm. An average depth of 2 mm or more ensures the strength of the sealing portion. The average depth of the sealing portion is preferably 3 mm or more. Furthermore, by making the average depth of the sealing portion 8 mm or less, it prevents the area of ​​the partition wall trapping particulate matter in the compartment from becoming smaller. The average depth of the sealing portion is preferably 7 mm or less. The depth of the sealing portion in the compartment extension direction is measured at any 20 locations on each end face, and the average value is taken as the average depth of the sealing portion on each end face. The depth of each sealing portion refers to the length in the compartment extension direction from the position of the inlet or outlet end face where the sealing portion is formed to the deepest position where the sealing portion exists.

[0138] Honeycomb structures can also be used as catalyst supports. A catalyst appropriate to the desired effect can be supported on the surface of the partition walls. The catalyst is preferably supported in the inlet chamber. There are no limitations on the catalyst; examples include oxidation catalysts (DOC) used to increase exhaust gas temperature by oxidizing and burning hydrocarbons (HC) and carbon monoxide (CO), PM combustion catalysts to assist in the combustion of PM such as soot, SCR catalysts and NSR catalysts for removing nitrogen oxides (NOx), and three-way catalysts capable of simultaneously removing hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). The catalyst may appropriately contain, for example, noble metals (Pt, Pd, Rh, etc.), alkali metals (Li, Na, K, Cs, etc.), alkaline earth metals (Mg, Ca, Ba, Sr, etc.), rare earth elements (Ce, Sm, Gd, Nd, Y, La, Pr, etc.), and transition metals (Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, Zr, V, Cr, etc.).

[0139] (2. Manufacturing method of honeycomb structure)

[0140] The following describes an illustrative method for manufacturing a columnar honeycomb structure according to one embodiment of the present invention. First, a raw material composition containing cordierite, a pore-forming material, a dispersion medium, and a binder is mixed to form a blank. This blank is then extruded to obtain a columnar honeycomb structure with outer peripheral walls and multiple compartments. These compartments are arranged on the inner peripheral side of the outer peripheral walls, extending from the inlet end face to the outlet end face, and both the inlet and outlet end faces have openings. Dispersants, other ceramic raw materials, and other additives can be added to the raw material composition as needed. During extrusion molding, a mold with the desired overall shape, compartment shape, compartment arrangement, wall thickness, and compartment density can be used.

[0141] Cordierite raw material refers to raw material that has been calcined to become cordierite, for example, it can be provided in powder form. Cordierite raw material preferably has the following chemical composition: alumina (Al2O3) (including aluminum hydroxide components that are converted into alumina): 30-45% by mass, magnesium oxide (MgO): 11-17% by mass, and silicon dioxide (SiO2): 42-57% by mass.

[0142] Examples of dispersion media include water, or mixtures of water and organic solvents such as alcohols, with water being particularly preferred.

[0143] The content of the dispersion medium in the honeycomb molded body before the drying process is preferably 20 to 110 parts by weight relative to 100 parts by weight of cordierite raw material, more preferably 25 to 100 parts by weight, and even more preferably 30 to 90 parts by weight. By making the content of the dispersion medium in the honeycomb molded body 20 parts by weight or more relative to 100 parts by weight of cordierite raw material, it is easy to obtain the advantage of stable quality of the honeycomb structure. By making the content of the dispersion medium in the honeycomb molded body 90 parts by weight or less relative to 100 parts by weight of cordierite raw material, the shrinkage during drying is reduced, and deformation can be suppressed. In this specification, the content of the dispersion medium in the honeycomb molded body refers to the value measured by the drying loss method.

[0144] As a pore-forming material, there are no particular limitations on any material that becomes porous after calcination. Examples include wheat flour, starch, foaming resin, water-absorbing resin, silica gel, carbon (e.g., graphite), ceramic balls, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic resin, and phenol. A single pore-forming material can be used, or two or more can be used in combination. From the viewpoint of improving the porosity of the calcined honeycomb structure, the content of the pore-forming material relative to 100 parts by weight of the cordierite raw material is preferably 3 parts by weight or more, more preferably 6 parts by weight or more, and even more preferably 9 parts by weight or more. From the viewpoint of ensuring the strength of the calcined honeycomb structure, the content of the pore-forming material relative to 100 parts by weight of the cordierite raw material is preferably 30 parts by weight or less, more preferably 27 parts by weight or less, and even more preferably 24 parts by weight or less.

[0145] Examples of adhesives include organic adhesives such as methylcellulose, hydroxypropoxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. Furthermore, from the viewpoint of improving the strength of the honeycomb molded body before calcination, the adhesive content relative to 100 parts by weight of cordierite raw material is preferably 4 parts by weight or more, more preferably 4.5 parts by weight or more, and even more preferably 5 parts by weight or more. From the viewpoint of suppressing cracking caused by abnormal heating during the calcination process, the adhesive content relative to 100 parts by weight of cordierite raw material is preferably 9 parts by weight or less, more preferably 8 parts by weight or less, and even more preferably 7 parts by weight or less. One type of adhesive can be used alone, or two or more can be used in combination.

[0146] Dispersants can include ethylene glycol, dextrin, fatty acid soaps, polyether polyols, etc. A single dispersant can be used, or two or more can be used in combination. The preferred content of the dispersant relative to 100 parts by weight of cordierite petrochemical feedstock is 0 to 2 parts by weight.

[0147] The drying of honeycomb molded bodies can be carried out using conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. Among these methods, a combination of hot air drying and microwave drying or dielectric drying is preferred, considering the ability to dry the honeycomb molded body quickly and uniformly.

[0148] After drying the honeycomb molded body, sealing portions are formed on both end faces of the honeycomb molded body. Each sealing portion can be formed by filling the openings of the inlet and outlet compartments where the sealing portions are to be formed with a sealing portion slurry, and then drying and calcining the filled slurry. The sealing portion forming slurry can be made from the material of the honeycomb molded body. Although not limited, for example, if the honeycomb molded body contains cordierite raw material, pore-forming material, dispersion medium, and binder, the sealing portion forming slurry can contain cordierite raw material, pore-forming material, dispersion medium, and binder.

[0149] Examplely, the slurry for forming the sealing portion contains, relative to 100 parts by weight of cordierite raw material, 30-60 parts by weight of dispersion medium, 5-20 parts by weight of pore-forming material, and 0.2-2.0 parts by weight of binder. In a preferred embodiment, the slurry for forming the sealing portion contains, relative to 100 parts by weight of cordierite raw material, 35-50 parts by weight of dispersion medium, 8-16 parts by weight of pore-forming material, and 0.2-1.5 parts by weight of binder.

[0150] Examples of dispersion media include water, or mixtures of water and organic solvents such as alcohols, with water being particularly preferred.

[0151] As a pore-forming material, there are no particular limitations as long as the material becomes porous after calcination. Examples include wheat flour, starch, foaming resin, water-absorbing resin, silica gel, carbon (e.g., graphite), ceramic balls, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic resin, phenol, etc. A single pore-forming material can be used, or two or more can be used in combination.

[0152] Examples of adhesives include organic adhesives such as methylcellulose, hydroxypropoxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. An adhesive can be used alone or in combination with two or more other types.

[0153] The slurry used to form the sealing portion may contain a dispersant. Examples of dispersants include ethylene glycol, dextrin, fatty acid soaps, and polyols. A single dispersant may be used, or two or more may be used in combination.

[0154] The filling of the opening of the compartment with slurry to form the sealing section can be achieved, for example, by the following "scraper method". Figure 4 As shown, a membrane 121 is attached to the upper end face (exit end face 106 in the figure) of the dried honeycomb molded body 400 fixed by a chuck 120. A laser is irradiated onto the membrane 121 at the position corresponding to the arrangement conditions of the sealing part, and multiple holes 126 are made in the membrane 121.

[0155] Then, a slurry 124 for forming the sealing portion is placed on the membrane 121, and the scraper 122 is moved along the membrane 121 towards... Figure 4 The operation moves in the direction of the arrow in the image. As a result, a constant amount of sealing slurry 124 is filled into the compartment 125, which opens at the position corresponding to the hole 126 in the membrane 121.

[0156] The depth of the sealing section can vary depending on the number of times the scraper 122 moves, the contact angle between the scraper 122 and the membrane 121, the pressing pressure of the scraper 122 on the membrane 121, and the viscosity of the slurry 124 used to form the sealing section.

[0157] After filling the sealing portion forming slurry 124, the membrane 121 is peeled off, and the honeycomb molded body 400 is dried as a whole. Thus, the sealing portion forming slurry 124 filled in the compartment 125 is dried, forming the sealing portion before calcination. Drying can be carried out at a drying temperature of, for example, 100–230°C, for approximately 60–150 seconds. After drying, the sealing portion protrudes from the end face of the honeycomb molded body by an amount corresponding to the thickness of the membrane; therefore, it is trimmed off as needed.

[0158] The material of the film is not particularly limited, but in order to facilitate the thermal processing for forming pores, polypropylene (PP), polyethylene terephthalate (PET), polyimide, or Teflon (registered trademark) is preferred. In addition, the film preferably has an adhesive layer, and the material of the adhesive layer is preferably an acrylic resin, a rubber-based material (for example, a rubber mainly composed of natural rubber or synthetic rubber), or a silicone-based resin. A thin film can be suitably used, for example, an adhesive film with a thickness of 20 to 50 μm.

[0159] In addition to the above-mentioned "doctor blade method", as a method for filling the slurry for forming the sealing portion into the opening portion of the compartment, a "pressing method" can be cited. The "pressing method" is as follows: paste the film, immerse the end face portion of the honeycomb formed body provided with holes in a liquid tank storing the slurry for forming the sealing portion, and fill the slurry for forming the sealing portion into the compartment. In this case, the depth of the sealing portion can be varied according to the depth to which the honeycomb formed body is immersed in the slurry for forming the sealing portion.

[0160] The honeycomb formed body filled with the slurry for forming the sealing portion is then subjected to a degreasing process and a calcination process, thereby manufacturing a honeycomb structure. The combustion temperature of the binder is about 200°C, and the combustion temperature of the pore-forming material is about 300 to 1000°C. Therefore, the degreasing process can be carried out by heating the honeycomb formed body within a range of about 200 to 1000°C. The heating time is not particularly limited and is usually about 10 to 100 hours. The honeycomb formed body after the degreasing process is called a pre-sintered body. The calcination process also depends on the material composition of the honeycomb structure. For example, it can be carried out by heating the pre-sintered body to 1300 to 1450°C and holding it for 3 to 24 hours.

[0161] The catalyst can be supported on the partition walls of the honeycomb structure manufactured in this way. As a method for supporting the catalyst on the partition walls, illustratively, a method can be cited in which the catalyst slurry is introduced into the compartment by a conventionally known suction method or the like, adhered to the surface and pores of the partition walls, and then a high-temperature treatment is carried out to sinter and support the catalyst contained in the catalyst slurry on the partition walls. The types of catalysts are as described above.

[0162] [Examples]

[0163] Hereinafter, examples for better understanding of the present invention and its advantages are illustrated, but the present invention is not limited to the examples.

[0164] <A. First Embodiment>

[0165] (A1. Manufacture of Honeycomb Structure)

[0166] [Honeycomb Structure Made of Cordierite: Examples 1-1 to 1-11, Comparative Examples 1-1 to 1-9]

[0167] To 100 parts by weight of cordierite petrochemical raw material, 0.5 parts by weight of pore-forming material, 1 part by weight of dispersion medium, and 6 parts by weight of organic binder were added, and the mixture was stirred and kneaded to prepare clay bricks. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as the cordierite petrochemical raw material. Water was used as the dispersion medium. Methylcellulose was used as the organic binder. A water-absorbing resin with a median particle size of 20 μm was used as the pore-forming material. The median particle size of the raw material refers to the particle size (D50) at which the cumulative value in the particle size distribution determined by laser diffraction / scattering method reaches 50%.

[0168] Next, the adobe was extruded using a mold with a honeycomb forming mechanism to obtain a honeycomb molded body with an overall cylindrical shape. The structure of the mold varied according to the test number.

[0169] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0170] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined compartments on the inlet end face side and the openings of remaining compartments on the outlet end face side of the dried honeycomb molded body, so that the inlet compartments and outlet compartments are alternately adjacent.

[0171] Next, the honeycomb molded body with each sealing portion was degreased and calcined to manufacture the honeycomb structures involved in each test number. The inlet and outlet end faces of the resulting honeycomb structures were cylindrical with circular shapes. The diameter of the inlet and outlet end faces was 228.6 mm. The length of the cell extension direction of the honeycomb structure was 184.2 mm. Except for the inlet cell adjacent to the outer peripheral sidewall, the opening shape of the inlet cell was octagonal. Except for the outlet cell adjacent to the outer peripheral sidewall, the opening shape of the outlet cell was square. The average depth of the sealing portion of the inlet and outlet end faces was approximately 7 mm. A number of honeycomb structures required to determine the following characteristics were prepared.

[0172] (A2. Structural characteristics of honeycomb structures)

[0173] For the honeycomb structures involved in each of the above-mentioned test numbers, the following structural characteristics are shown in Table 1.

[0174] • Compartment density

[0175] • Average thickness of the partition

[0176] • The average opening diameter D of the multiple inlet compartments, excluding the inlet compartments adjacent to the outer peripheral sidewall.in

[0177] • The average opening diameter D of the multiple discharge compartments, excluding the discharge compartments adjacent to the outer peripheral sidewall. out

[0178] • Opening diameter ratio (D) in / D out )

[0179] • Average porosity of the partition

[0180] • The ratio of the number of inlet compartments to the number of outlet compartments

[0181] • Density (mass of the honeycomb structure ÷ external dimensions)

[0182] The compartment density refers to the total number of inlet and outlet compartments, measured according to the method described above.

[0183] The average thickness of the septum was observed by scanning electron microscopy (SEM) or measured by a microscope.

[0184] The opening diameters of the inlet and outlet compartments were observed using a scanning electron microscope (SEM) or calculated using a microscope.

[0185] The average value D is calculated based on the opening diameter of all discharge compartments except those adjacent to the outer peripheral sidewall. out .

[0186] The average value D is calculated based on the opening diameter of all inlet compartments except those adjacent to the outer peripheral sidewall. in .

[0187] The porosity of the adjacent structures was measured using the mercury intrusion porosimetry method described above with an Autopore 9500 (trade name) manufactured by Micromeritics.

[0188] The ratio of the number of inlet compartments to the number of outlet compartments is calculated by visually counting the number of outlet compartments and the number of inlet compartments.

[0189] (A3. Functional characteristics of honeycomb structures)

[0190] The honeycomb structures involved in each of the above-prepared test numbers were used as exhaust gas filters, and the following characteristics were evaluated.

[0191] [Pressure Loss Characteristics]

[0192] An exhaust gas filter is mounted on the exhaust system of a diesel engine with a displacement of 13 liters, and a test is conducted to accumulate soot on the filter. Further, when soot accumulates, the fuel injection pressure is reduced in a manner that easily generates soot, and the engine is operated under low-temperature conditions where the exhaust gas temperature at the inlet of the filter is less than 280°C so that the soot does not burn. The pressure loss at the start of the test (before soot accumulation) (initial pressure loss), the pressure loss (P1) when the soot accumulation amount per 1 L of filter volume (g) is 1 g / L, and the pressure loss (P2) when the soot accumulation amount per 1 L of filter volume (g) is 3 g / L are measured. When measuring the pressure loss, the engine output is increased, and the pressure loss is measured when exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr at the inlet of the filter passes from the inlet end face to the outlet end face. The results are shown in Table 1.

[0193] Based on Comparative Example 1, which is a representative example of the honeycomb structure related to the prior art, all the pass criteria for the pressure loss characteristics satisfy the following conditions.

[0194] The initial pressure loss is less than 1.17 kPa;

[0195] The pressure loss (P1) when the soot accumulation amount is 1 g / L is 2.61 kPa or less;

[0196] The pressure loss (P2) when the soot accumulation amount is 3 g / L is 3.69 kPa or less;

[0197] (P2 - P1) / P1 as an index of the pressure loss inclination is 45% or more.

[0198] [Table 1]

[0199]

[0200] [Discussion]

[0201] The combinations of the compartment density, the average thickness of the partition wall, and the opening diameter ratio in Comparative Examples 1-1 to 1-9 are inappropriate. As a result, the pressure loss becomes too large, the pressure loss inclination is small, and the density decreases (the heat capacity decreases). In contrast, in Examples 1-1 to 1-11, the combinations of the compartment density, the average thickness of the partition wall, and the opening diameter ratio are appropriate. Therefore, the initial pressure loss and the pressure loss during soot accumulation do not increase excessively. On the other hand, a large pressure loss inclination is obtained. In addition, a practical heat capacity is obtained in view of the density.

[0202] <B. Second Embodiment>

[0203] (B1. Manufacture of Honeycomb Structure)

[0204] [Honeycomb structures made of cordierite: Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-7]

[0205] To 100 parts by weight of cordierite petrochemical raw material, 0.5 parts by weight of pore-forming material, 1 part by weight of dispersion medium, and 6 parts by weight of organic binder were added, and the mixture was stirred and kneaded to prepare clay bricks. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as the cordierite petrochemical raw material. Water was used as the dispersion medium. Methylcellulose was used as the organic binder. A water-absorbing resin with a median particle size of 20 μm was used as the pore-forming material. The median particle size of the raw material refers to the particle size (D50) at which the cumulative value in the particle size distribution determined by laser diffraction / scattering method reaches 50%.

[0206] Next, the adobe was extruded using a mold with a honeycomb forming mechanism to obtain a honeycomb molded body with an overall cylindrical shape. The structure of the mold varied according to the test number.

[0207] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0208] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined compartments on the inlet end face side and the openings of remaining compartments on the outlet end face side of the dried honeycomb molded body, so that the inlet compartments and outlet compartments are alternately adjacent.

[0209] Next, the honeycomb molded body with each sealing portion was degreased and calcined to manufacture the honeycomb structures involved in each test number. The inlet and outlet end faces of the resulting honeycomb structures were cylindrical with circular shapes. The diameter of the inlet and outlet end faces was 228.6 mm. The length of the cell extension direction of the honeycomb structure was 184.2 mm. Except for the inlet cell adjacent to the outer peripheral sidewall, the opening shape of the inlet cell was octagonal. Except for the outlet cell adjacent to the outer peripheral sidewall, the opening shape of the outlet cell was square. The average depth of the sealing portion of the inlet and outlet end faces was approximately 7 mm. A number of honeycomb structures required to determine the following characteristics were prepared.

[0210] (B2. Structural characteristics of honeycomb structures)

[0211] For the honeycomb structures involved in each of the above-mentioned test numbers, the following structural characteristics are shown in Table 2.

[0212] • Compartment density

[0213] • Average thickness of the partition

[0214] • The average opening diameter D of the multiple inlet compartments, excluding the inlet compartments adjacent to the outer peripheral sidewall. in

[0215] • The average opening diameter D of the multiple discharge compartments, excluding the discharge compartments adjacent to the outer peripheral sidewall. out

[0216] • Opening diameter ratio (D) in / D out )

[0217] • Average porosity of the partition

[0218] • The ratio of the number of inlet compartments to the number of outlet compartments

[0219] Average pore size

[0220] • Density (mass of the honeycomb structure ÷ external dimensions)

[0221] The compartment density refers to the total number of inlet and outlet compartments, measured according to the method described above.

[0222] The average thickness of the septum was observed by scanning electron microscopy (SEM) or measured by a microscope.

[0223] The opening diameters of the inlet and outlet compartments were observed using a scanning electron microscope (SEM) or calculated using a microscope.

[0224] The average value D is calculated based on the opening diameter of all discharge compartments except those adjacent to the outer peripheral sidewall. out .

[0225] The average value D is calculated based on the opening diameter of all inlet compartments except those adjacent to the outer peripheral sidewall. in .

[0226] The porosity of the adjacent structures was measured using the mercury intrusion porosimetry method described above with an Autopore 9500 (trade name) manufactured by Micromeritics.

[0227] The ratio of the number of inlet compartments to the number of outlet compartments is calculated by visually counting the number of outlet compartments and the number of inlet compartments.

[0228] The average pore size of the septum was measured using the above-described mercury intrusion porosimetry method with an Autopore 9500 (trade name) manufactured by Micromeritics.

[0229] (B3. Functional characteristics of honeycomb structures)

[0230] The honeycomb structures involved in each of the above-prepared test numbers were used as exhaust gas filters, and the pressure loss characteristics were investigated to be the same as those of the honeycomb structures in Examples 1-1, etc. The results are shown in Table 2.

[0231] [Table 2]

[0232]

[0233] [Inspection]

[0234] The combination of compartment density, average wall thickness, opening diameter ratio, and average porosity of the compartments in Comparative Examples 2-1 to 2-7 was inappropriate. Therefore, the pressure loss became excessive, the pressure loss tilt was small, and the density decreased (heat capacity decreased). In contrast, in Examples 2-1 to 2-10, the compartment density, wall thickness, opening diameter ratio, etc., were appropriate; therefore, the initial pressure loss and the pressure loss during soot accumulation did not increase excessively, and a large pressure loss tilt was obtained. Furthermore, a practical heat capacity was achieved due to the density.

[0235] Symbol Explanation

[0236] 100—Honeycomb structure; 102—Outer peripheral sidewall; 104—Inlet end face; 106—Outlet end face; 107—Opening; 108—Inlet compartment; 109—Sealing section; 110—Discharge compartment; 112—Partition wall; 120—Chuck; 121—Membrane; 122—Scraper; 124—Slurry for forming the sealing section; 125—Compartment; 126—Pore; 400—Honeycomb forming body.

Claims

1. A honeycomb structure, a columnar honeycomb structure, comprising: an outer peripheral sidewall; a plurality of inlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having an opening at the inlet end face and a sealing portion at the outlet end face; and a plurality of outlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having a sealing portion at the inlet end face and an opening at the outlet end face, characterized in that, At least a portion of the inlet compartments and at least a portion of the outlet compartments are adjacent to each other across a partition wall. The compartment density, based on the total number of the plurality of inlet compartments and the plurality of outlet compartments, is 29~43 compartments / cm². 2 , The average thickness of the partition wall is greater than 0.173 mm and less than 0.236 mm. Let D be the average opening diameter of the discharge compartments excluding those adjacent to the outer peripheral sidewall. out Let D be the average opening diameter of the plurality of inlet compartments excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then 1.20 ≤ D is satisfied. in / D out ≤1.

38.

2. The honeycomb structure according to claim 1, characterized in that, Apart from the inlet compartments adjacent to the outer peripheral sidewalls, the average opening diameter D of each of the plurality of inlet compartments is... in For thicknesses between 1.48mm and 1.80mm, Except for the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out It is between 1.16mm and 1.48mm.

3. The honeycomb structure according to claim 1 or 2, characterized in that, The average porosity of the partition wall is 52-60%.

4. The honeycomb structure according to claim 1 or 2, characterized in that, The density, measured based on the external dimensions, is 0.288~0.410 g / cm³. 3 .

5. The honeycomb structure according to claim 1 or 2, characterized in that, The ratio of the number of inlet compartments (excluding those adjacent to the outer peripheral sidewall) to the number of outlet compartments (excluding those adjacent to the outer peripheral sidewall) is 0.9 to 1.

1.

6. The honeycomb structure according to claim 1 or 2, characterized in that, If the mass of particulate matter containing soot per unit volume of the honeycomb structure is 1 g / L, then the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P1. When the mass of particulate matter containing soot per unit volume of the honeycomb structure is 3 g / L, the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P2. Then it satisfies 45%≤(P2-P1) / P1.

7. The honeycomb structure according to claim 1 or 2, characterized in that, The partition wall contains cordierite.

8. A honeycomb structure, a columnar honeycomb structure, comprising: an outer peripheral sidewall; a plurality of inlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having an opening at the inlet end face and a sealing portion at the outlet end face; and a plurality of outlet chambers disposed on the inner peripheral side of the outer peripheral sidewall, extending from an inlet end face to an outlet end face, having a sealing portion at the inlet end face and an opening at the outlet end face, characterized in that... At least a portion of the inlet compartments and at least a portion of the outlet compartments are adjacent to each other across a partition wall. The compartment density, based on the total number of the plurality of inlet compartments and the plurality of outlet compartments, is 29-36 compartments / cm². 2 , The average thickness of the partition wall is greater than 0.231 mm and less than 0.312 mm. Let D be the average opening diameter of the discharge compartments excluding those adjacent to the outer peripheral sidewall. out Let D be the average opening diameter of the plurality of inlet compartments excluding the inlet compartments adjacent to the outer peripheral sidewall. in Then 1.14 ≤ D in / D out ≤1.37, The average porosity of the partition wall is 57-63%.

9. The honeycomb structure according to claim 8, characterized in that, Apart from the inlet compartments adjacent to the outer peripheral sidewalls, the average opening diameter D of each of the plurality of inlet compartments is... in For thicknesses between 1.52mm and 1.76mm, Except for the discharge compartments adjacent to the outer peripheral sidewall, the average value D of the opening diameter of each of the plurality of discharge compartments is... out It is between 1.20mm and 1.44mm.

10. The honeycomb structure according to claim 8 or 9, characterized in that, The average pore size of the partition wall is 7~13μm.

11. The honeycomb structure according to claim 8 or 9, characterized in that, The density, measured based on the external dimensions, is 0.288~0.410 g / cm³. 3 .

12. The honeycomb structure according to claim 8 or 9, characterized in that, The ratio of the number of inlet compartments (excluding those adjacent to the outer peripheral sidewall) to the number of outlet compartments (excluding those adjacent to the outer peripheral sidewall) is 0.9 to 1.

1.

13. The honeycomb structure according to claim 8 or 9, characterized in that, If the mass of particulate matter containing soot per unit volume of the honeycomb structure is 1 g / L, then the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P1. When the mass of particulate matter containing soot per unit volume of the honeycomb structure is 3 g / L, the pressure loss of exhaust gas at a temperature of 250°C and a flow rate of 480 kg / hr passing from the inlet end face to the outlet end face is defined as P2. Then it satisfies 45%≤(P2-P1) / P1.

14. The honeycomb structure according to claim 8 or 9, characterized in that, The partition wall contains cordierite.

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