JP2016150282A - Honeycomb structure, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure which can suitably collect particulate matters contained in exhaust gas, can effectively suppress outflow of the collected particulate matters to an external, and can suppress clog of an end surface of the honeycomb structure by the particulate matters.SOLUTION: A honeycomb structure includes a honeycomb base material 4 having porous barrier walls 1 for partitioning a plurality of cells 2. The cells 2 include through cells 2a and gas inflow end surface sealing cells 2b. As for the respective through cell 2a and two adjacent gas inflow end surface sealing cells 2b, lengths of sealing parts 5 in a direction of the cell 2 extending from an exhaust gas inflow end surface 11 are different in the respective cells 2. As for the two gas inflow end surface sealing cells 2b, the sealing parts 5 are mirror-image asymmetric with the adjacent through cell 2a interposed therebetween.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a honeycomb structure and a manufacturing method thereof. More specifically, the particulate matter contained in the exhaust gas can be suitably collected, the outflow of the collected particulate matter to the outside can be effectively suppressed, and the honeycomb structure made of the particulate matter The present invention relates to a honeycomb structure capable of suppressing end face clogging and a manufacturing method thereof.

  In recent years, collection of particulate matter mainly composed of carbon discharged from an internal combustion engine such as an automobile, particularly a diesel engine, has been demanded along with stricter exhaust gas regulations. These particulate substances are also called “particulate matter” or simply “PM” and are known to cause environmental pollution when released into the atmosphere. Ceramic filters (diesel particulate filters, or simply “DPF”) are widely used in exhaust gas systems of diesel engines for the purpose of collecting these PMs. As the DPF, for example, one end portion of a predetermined cell and the other end portion of the remaining cell are plugged, and both end surface plugging in which the predetermined cell and the remaining cell are alternately arranged A honeycomb structure is known (see, for example, Patent Document 1). In such a DPF, exhaust gas flows into the cell from the exhaust gas inflow end face, and the exhaust gas that has flowed into the cell passes through the partition wall, and exhaust gas purified through the partition wall (also referred to as “purified gas”). The exhaust gas is discharged from the end face of the exhaust gas. Here, when the exhaust gas passes through the partition, PM contained in the exhaust gas is collected by the partition and the exhaust gas is purified.

  However, in the conventional plugged honeycomb structure on both end faces, all of the exhaust gas that has flowed in passes through the partition walls, and most of the PM in the exhaust gas is collected by the partition walls, so that the pressure loss tends to increase. In addition, there is a problem that ash is generated by impurities contained in a trace amount in the engine oil or fuel, and the ash is accumulated in the DPF cell by a long time operation, thereby increasing pressure loss.

  In order to solve such problems, a honeycomb structure in which only the exhaust gas outflow end face is plugged has been proposed (see, for example, Patent Documents 2 to 4). A honeycomb structure in which only the exhaust gas inflow end face is plugged has also been proposed (see, for example, Patent Document 5).

JP 2003-254034 A JP 2002-537965 A Japanese Patent No. 39442086 JP 2004-251137 A International Publication No. 2012/046484

  However, the honeycomb structures described in Patent Documents 2 to 4 have a problem in that pressure loss increases with the use of the honeycomb filter because ash accumulates in the plugged cells. Further, in the honeycomb structure described in Patent Document 5, as shown in FIG. 13A, the particulate matter 813 tends to be easily deposited in the opening on the exhaust gas inflow end face side of the honeycomb structure. Here, FIG. 13A is a schematic view showing a cross section parallel to the cell extending direction of the conventional honeycomb structure. A honeycomb structure 800 shown in FIG. 13A is a honeycomb structure 800 in which plugging portions 805 are provided only on the inflow end surface 811. In such a honeycomb structure 800, a differential pressure is generated between the through-cell 802a and the gas inflow end-face plugged cell 802b from a location where the plugging portion 805 on the inflow end face 811 side is interrupted. In this honeycomb structure 800, a large amount of particulate matter 813 contained in the exhaust gas G is deposited in the vicinity of the portion where the plugging portion 805 on the inflow end face 811 side is interrupted. Therefore, when the deposition of the particulate matter 813 described above exceeds a certain amount, the particulate matter 813 locally deposited on the inflow end face 811 side is peeled off from the partition wall 801 as shown in FIG. 13B. There is. Even when the flow rate of the exhaust gas G flowing from the inflow end surface 811 increases, the particulate matter 813 locally deposited on the inflow end surface 811 side may be peeled off from the partition wall 801. Further, since the flow path of the through-cell 802a is easily blocked by the particulate matter 813, the flow rate of the exhaust gas G is increased at the closed portion, and the above-described separation of the particulate matter 813 may be more likely to occur. Then, the particulate matter 813 peeled off from the partition wall 801 passes through the through-cell 802 a and flows out from the outflow end surface 812 of the honeycomb structure 800. In this manner, the particulate matter 813 that has been peeled off from the partition wall 801 flows out of the outflow end surface 812 of the honeycomb structure 800 is hereinafter referred to as “blow-off”. Such a blow-off problem is a problem peculiar to the honeycomb structure 800 that has the through-cell 802a and collects the particulate matter 813 in the partition wall 801 that partitions the through-cell 802a. Currently, there is a demand for development of a honeycomb structure in which such blow-off is suppressed. FIG. 13B is a schematic diagram showing a state in which the honeycomb structure shown in FIG. 13A is blown off. In FIG. 13A and FIG. 13B, the code | symbol 803 shows an outer peripheral wall and the code | symbol 804 shows a honeycomb base material.

  The present invention has been made in view of such problems of the prior art. According to the present invention, the particulate matter contained in the exhaust gas can be suitably collected, and the outflow of the collected particulate matter to the outside can be effectively suppressed, and the honeycomb made of the particulate matter can be used. A honeycomb structure capable of suppressing clogging of the end face of the structure and a method for manufacturing the same are provided.

  According to the present invention, the following honeycomb structure and a manufacturing method thereof are provided.

[1] A honeycomb base material having a porous partition wall that defines a plurality of cells serving as fluid flow paths extending from an exhaust gas inflow end surface to an exhaust gas outflow end surface, and the cells are exhausted from the exhaust gas inflow end surface. A through-cell penetrating to an end face; and a gas inflow end-face plugged cell in which the exhaust gas inflow end face is blocked by a plugging portion, wherein at least one through-cell is at least two of the gas inflow end face plugs. In each of the at least two gas inflow end surface plugged cells adjacent to the stop cell and adjacent to the through cell, the length of the plugging portion in the cell extending direction from the exhaust gas inflow end surface Are different in each cell, and in the at least two gas inflow end facet plugged cells, the plugged portions sandwich non-mirrors between the adjacent through cells. It is symmetrical, the honeycomb structure.

[2] The cell cross section perpendicular to the cell extending direction is a polygon having a plurality of corners, and the corners in one cell of the gas inflow end face plugged cell start from the exhaust gas inflow end face. The honeycomb structure according to [1], wherein a maximum value of a difference in length in the cell extending direction of the plugged portion at each corner is 5 mm or more and 25 mm or less.

[3] In the corner portion in the one cell of the gas inflow end face plugged cell, the length in the cell extending direction of the plugging portion of each corner portion starts from the exhaust gas inflow end face. The honeycomb structure according to [2], which is 2 mm or more and 35 mm or less.

[4] The length of the plugging portion from each corner in the extending direction of the cell, starting from the exhaust gas inflow end surface, at the corner portion in the one cell of the gas inflow end surface plugged cell. The honeycomb structure according to [2] or [3], wherein two or less of the lengths are the same.

[5] The honeycomb structure according to any one of [1] to [4], wherein the number of the gas inflow end face plugged cells is 25 to 50% with respect to the total number of the cells.

[6] The number of through cells arranged so as to be adjacent to the two gas inflow end face plugged cells having the non-mirror symmetry is 50% or more with respect to the total number of the through cells. The honeycomb structure according to any one of the above [1] to [5].

[7] The honeycomb structure according to any one of [1] to [6], wherein the partition wall has a thickness of 150 to 410 μm.

[8] The honeycomb structure according to any one of [1] to [7], wherein the honeycomb substrate has a cell density of 15 to 62 cells / cm ² .

[9] A honeycomb formed body forming step of extruding a forming raw material to form a honeycomb formed body having partition walls that define a plurality of cells serving as fluid flow paths extending from one end face to the other end face. A film disposing step of disposing a film covering the cell opening on one end surface of the obtained honeycomb formed body or the honeycomb fired body obtained by firing the honeycomb formed body, and should not be plugged A plugging portion forming step of forming a plugging portion in at least two cells to be plugged adjacent to the cell, wherein the plugging portion forming step includes the cells to be plugged Forming a perforated part in a part of the film covering each of the film, wherein the center of gravity of the perforated part is deviated from the center of gravity of the cell opening of the cell to be plugged. The film is disposed By supplying the plugging material from the plugging material, plugging portions having different lengths in the cell extending direction of the plugging portion from the supply surface of the plugging material are formed in one cell. And a plugging material supply step.

[10] In the punching portion forming step, the cell opening is a polygon having a plurality of corners, and the center of gravity of the punching portion is the center of gravity of the cell opening and the corner of the cell opening. The method for manufacturing a honeycomb structured body according to the above [9], wherein the honeycomb structured body is displaced on a straight line passing through.

[11] The method for manufacturing a honeycomb structure according to [9], wherein, in the perforated part forming step, a center of gravity of the perforated part is shifted on a perpendicular drawn from a center of gravity of the cell opening to the partition wall.

[12] In the perforated part forming step, the center of gravity of the perforated part that perforates the film covering the cells to be plugged is not sandwiched between the films covering the cells not to be plugged. The method for manufacturing a honeycomb structured body according to any one of [9] to [11], wherein the perforated part is formed so as to have line symmetry.

[13] The method for manufacturing a honeycomb structured body according to any one of [9] to [12], wherein the plugging material has a viscosity of 100 to 400 Pa · s.

  According to the honeycomb structure of the present invention, the particulate matter contained in the exhaust gas can be suitably collected, and the collected particulate matter can be effectively prevented from flowing out to the outside. Clogging of the end face of the honeycomb structure due to the particulate material can be suppressed. That is, in the honeycomb structure of the present invention, when exhaust gas flows into a through cell in which no plugging portion is disposed, the pressure in the through cell increases, and the gas inflow end face plugging adjacent to the through cell is plugged. The pressure in the cell is relatively low with respect to the pressure in the through cell. For this reason, a part of the exhaust gas passes through the partition wall from the through cell and flows into the gas inflow end face plugged cell, and the side of the gas inflow end face plugged cell where the plugging portion is not provided (honeycomb base). Exhaust gas that has permeated through the partition wall is discharged from the end portion on the outflow end face side of the material. As described above, since part of the exhaust gas permeates the partition walls, the particulate matter contained in the exhaust gas accumulates on the partition walls in the through-cells, so that the particulate matter can be collected well. .

  And in this invention, in the gas inflow end surface plugged cell, the length of the cell extending direction of the plugging part from the exhaust gas inflow end surface is different in one cell. Furthermore, in the present invention, in at least two gas inflow end faced plugged cells adjacent to the through cell, the plugged portion is non-mirror image symmetric with respect to the through cell. Hereinafter, a through cell adjacent to at least two gas inflow end surface plugged cells having a non-mirror image symmetric plugged portion may be referred to as a “specific through cell”. In this invention, by having such a specific penetration cell, in the partition in a specific penetration cell, a difference can be provided in the starting point from the inflow end surface side where a particulate matter begins to deposit. That is, normally, in the specific through-cell, the exhaust gas hardly permeates through the partition wall where the plugging portion is disposed, and the portion where the plugging portion is not disposed in the partition wall (in other words, the plugging portion). Particulate matter will start to accumulate from the point where the stop is interrupted). Therefore, in the honeycomb structure of the present invention, the partition wall arranged to separate the specific through cell and the one gas inflow end face plugged cell, the specific through cell and the other gas inflow end face plugged cell. The position where the particulate matter starts to be deposited is different between the partition walls arranged separately. For this reason, the accumulation location of the particulate matter in the vicinity of the inflow end face of the honeycomb structure is shifted, and the end face clogging of the honeycomb structure due to the particulate matter can be suppressed. In other words, it is possible to effectively prevent the inside of the specific through cell from becoming narrow due to the accumulation of particulate matter. And if the flow path in the cell can be secured widely, even if the flow rate of the exhaust gas increases, the pressure applied to the accumulated particulate matter can be suppressed, and the particulate matter is prevented from peeling off from the partition wall. can do. Therefore, the honeycomb structure of the present invention can effectively suppress the outflow of the particulate matter once collected to the outside.

1 is a perspective view schematically showing a first embodiment of a honeycomb structure of the present invention as seen from an inflow end face side. FIG. FIG. 2 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. FIG. 3 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as viewed from the inflow end face side. FIG. 2 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. It is sectional drawing which shows A-A 'of FIG. 3 typically. FIG. 3 is an enlarged perspective view of the vicinity of the inflow end surface of the first embodiment of the honeycomb structure of the present invention. FIG. 4 is a cross-sectional view schematically showing A-A ′ in FIG. 3 and is a schematic diagram for explaining the flow of exhaust gas. It is an enlarged view which expands and shows the range enclosed with the broken line shown to the code | symbol X of FIG. 7A. It is an expansion see-through | perspective perspective view of the inflow end surface vicinity in 2nd embodiment of the honeycomb structure of this invention. It is an expansion see-through | perspective perspective view of the inflow end surface vicinity in 3rd embodiment of the honeycomb structure of this invention. It is a schematic diagram which shows the other example of the arrangement | sequence of a specific penetration cell and a gas inflow end surface plugged cell. It is a schematic diagram which shows the other example of the arrangement | sequence of a specific penetration cell and a gas inflow end surface plugged cell. It is a figure explaining the film arrangement | positioning process in one Embodiment of the manufacturing method of the honeycomb structure of this invention, Comprising: It is explanatory drawing which shows the state before arrange | positioning a film on one end surface of a honeycomb molded object. It is a figure explaining the film arrangement | positioning process in one Embodiment of the manufacturing method of the honeycomb structure of this invention, Comprising: It is explanatory drawing which shows the state after arrange | positioning the film on one end surface of the honeycomb molded body. It is a figure explaining the plugging part formation process in one embodiment of a manufacturing method of a honeycomb structure of the present invention, and is an explanatory view showing a step of forming a perforated part in a part of a film. It is a figure explaining the plugging part formation process in one embodiment of the manufacturing method of the honeycomb structure of the present invention, and is an explanatory view showing the step of forming a plugging part. It is a figure explaining the plugging part formation process in one embodiment of the manufacturing method of the honeycomb structure of the present invention, and is an explanatory view showing the step of forming a plugging part. It is explanatory drawing which shows typically the pattern A of the plugging in an Example. It is explanatory drawing which shows typically the pattern B of the plugging in an Example. It is explanatory drawing which shows typically the pattern C of the plugging in an Example. It is a schematic diagram for demonstrating the punching position of the punching part in an Example. It is a schematic diagram for demonstrating the punching position of the punching part in an Example. It is a schematic diagram for demonstrating the punching position of the punching part in an Example. It is a schematic diagram which shows a cross section parallel to the cell extending direction of the conventional honeycomb structure. FIG. 13B is a schematic diagram showing a state where the honeycomb structure shown in FIG. 13A is blown off.

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. Accordingly, it is understood that modifications, improvements, and the like to the following embodiments are also included in the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

(1) Honeycomb structure:
As shown in FIG. 1 to FIG. 6, the first embodiment of the honeycomb structure of the present invention has a porous partition wall 1 that partitions and forms a plurality of cells 2 that serve as fluid (ie, exhaust gas G) flow paths. This is a honeycomb structure 100 including the honeycomb substrate 4. The partition wall 1 defines a plurality of cells 2 extending from the exhaust gas inflow end surface 11 which is an end surface on the exhaust gas G inflow side to the exhaust gas outflow end surface 12 which is an end surface on the exhaust gas G outflow side. Hereinafter, the “exhaust gas inflow end surface 11” may be simply referred to as “inflow end surface 11”. Hereinafter, the “exhaust gas outflow end face 12” may be simply referred to as “outflow end face 12”. In the honeycomb structure 100 of the present embodiment, the plurality of cells 2 include through cells 2a and gas inflow end face plugged cells 2b. The penetration cell 2a is a cell 2 that penetrates substantially from the inflow end face 11 side to the outflow end face 12 side. The gas inflow end face plugged cell 2 b is a cell 2 in which the end of the cell 2 is substantially closed by the plugging portion 5 on the inflow end face 11 side of the honeycomb substrate 4.

  In the honeycomb structure 100 of the present embodiment, at least one penetration cell 2a is disposed adjacent to at least two gas inflow end face plugged cells 2b. In each of the at least two gas inflow end face plugged cells 2b, the length of the plugging portion 5 in the extending direction of the cell 2 from the inflow end face 11 is set to each cell 2 (specifically, each gas It differs in the inflow end face plugging cell 2b). Further, in the honeycomb structure 100 of the present embodiment, in the at least two gas inflow end face plugged cells 2b, the plugged portions 5 are non-mirror image symmetric with respect to the adjacent through cell 2a. Hereinafter, the through cell 2a adjacent to each of the at least two gas inflow end surface plugged cells 2b having the non-mirror image symmetric plugged portion 5 may be referred to as a “specific through cell 2aa”. That is, the “specific penetration cell 2aa” is the penetration cell 2a arranged so as to be adjacent to the two gas inflow end face plugged cells 2b having a non-mirror symmetry relationship. Here, the penetration cell 2a and the gas inflow end face plugged cell 2b are adjacent to each other in the cross section perpendicular to the cell 2 extending direction of the honeycomb substrate 4 in the cross section of the through cell 2a and the gas inflow end face plugged cell 2b. This means that the partition wall 1 is defined by the common partition wall 1. In particular, in the cross section, when the shape of the through cell 2a and the gas inflow end face plugged cell 2b is a polygon, one side of the through cell 2a and one side of the gas inflow end face plugged cell 2b are separated from each other by the partition wall 1. It is said to be adjacent to each other.

  In the honeycomb structure 100 shown in FIGS. 1 to 6, the specific through cell 2aa is arranged adjacent to the two gas inflow end face plugged cells 2b. Here, the two gas inflow end face plugged cells 2b adjacent to the specific through cell 2aa are defined as a first gas inflow end face plugged cell 2ba and a second gas inflow end face plugged cell 2bb. The first gas inflow end face plugged cell 2ba and the second gas inflow end face plugged cell 2bb have a quadrangular shape in a cross section perpendicular to the cell 2 extending direction of the honeycomb substrate 4. Here, the four vertices of the quadrangle in the cross section of the first gas inflow end face plugging cell 2ba are the vertex O2, the vertex O3, and the vertex O4 in the clockwise direction when viewed from the inflow end face side from the one vertex O1. To do. Further, the four apexes of the quadrilateral in the cross section of the second gas inflow end face plugged cell 2bb are arranged in the counterclockwise direction as viewed from the inflow end face side from the one apex P1, and the apexes P2, P3, and P4 To do. Each of the vertex O1 and the vertex P1, the vertex O2 and the vertex P2, the vertex O3 and the vertex P3, and the vertex O4 and the vertex P4 are in a mirror image positional relationship with the specific penetration cell 2aa interposed therebetween.

  On the inflow end face 11 side of the first gas inflow end face plugged cell 2ba and the second gas inflow end face plugged cell 2bb, plugging portions 5a and 5b are arranged. In the first gas inflow end face plugging cell 2ba, the length of the plugging portion 5a in the cell 2 extending direction from the inflow end face 11 is the length T1 at the vertex O1, the length T2 at the vertex O2, and the vertex O3. Is the length T2, and the vertex O4 is the length T1. On the other hand, in the second gas inflow end face plugged cell 2bb, the length in the cell 2 extending direction of the plugged portion 5b from the inflow end face 11 is the length T2 at the vertex P1, the length T1 at the vertex P2, The vertex P3 has a length T1, and the vertex P4 has a length T2. As described above, in the honeycomb structure of the present embodiment, plugging is performed at the vertex O1 and the vertex P1, the vertex O2 and the vertex P2, the vertex O3 and the vertex P3, and the vertex O4 and the vertex P4 in the mirror image positional relationship. The lengths of the portions 5a and 5b in the extending direction of the cell 2 are different. In the present specification, “the plugged portion 5 is non-mirror image symmetric with respect to the adjacent penetrating cell 2a”, as described above, vertices in a mirror image positional relationship, for example, the vertex O1 and the vertex P1 , It means that the lengths of the plugged portions 5a, 5b in the extending direction of the cells 2 are different. In the honeycomb structure 100 shown in FIGS. 1 to 6, in all of the vertexes O1 and P1, the vertex O2 and the vertex P2, the vertex O3 and the vertex P3, and the vertex O4 and the vertex P4 in the mirror image positional relationship, The lengths of the sealing portions 5a and 5b in the extending direction of the cells 2 are different. However, in at least one of the vertex O1 and the vertex P1, the vertex O2 and the vertex P2, the vertex O3 and the vertex P3, and the vertex O4 and the vertex P4, the length in the extending direction of the cell 2 of the plugged portions 5a and 5b. If they are different, it can be said that they are non-mirror image symmetric. That is, the lengths of the plugging portions 5a and 5b in the cell 2 extending direction are the same in all of the vertex O1 and the vertex P1, the vertex O2 and the vertex P2, the vertex O3 and the vertex P3, and the vertex O4 and the vertex P4. Is a mirror image symmetry, and a case other than such a mirror image symmetry is a non-mirror image symmetry.

  Here, “the end portion of the cell is“ substantially blocked by the plugged portion ”” means that the end portion of the cell is blocked by the plugged portion so that the exhaust gas hardly passes through the cell. It means a state. There may be a small amount of gas flow passing through the plugged portion due to the slight gap formed during the plugging formation and the plugged portion 5 being a porous body. Further, “the cell penetrates“ substantially ”” means a state in which the exhaust gas can pass through the cell. This includes a case where the exhaust gas can pass through the cell even if the plugged portion or the like is disposed in the cell due to a state where a hole is opened in the plugged portion or the like. Further, in the columnar honeycomb structure 100 as shown in FIG. 1, the “cell extending direction” means the direction of the central axis of the columnar honeycomb structure 100. The “length of the plugged portion 5” means the length of the plugged portion 5 in the cell extending direction.

  FIG. 1 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the inflow end face side. FIG. 2 is a perspective view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the outflow end face side. FIG. 3 is a plan view schematically showing the first embodiment of the honeycomb structure of the present invention as seen from the inflow end face side. FIG. 4 is a plan view seen from the outflow end face side, schematically showing the first embodiment of the honeycomb structure of the present invention. FIG. 5 is a cross-sectional view schematically showing A-A ′ of FIG. 3. FIG. 6 is an enlarged perspective view of the vicinity of the inflow end face of the first embodiment of the honeycomb structure of the present invention.

  According to the honeycomb structure of the present embodiment, the particulate matter contained in the exhaust gas can be collected favorably, and the outflow of the collected particulate matter to the outside can be effectively suppressed. The end face clogging of the honeycomb structure due to the particulate matter can be suppressed. That is, as shown in FIG. 7A, according to the honeycomb structure 100 of the present embodiment, when the exhaust gas G is caused to flow from the inflow end face 11 of the honeycomb substrate 4, the particulate matter contained in the exhaust gas G is The through-cell 2a can be collected by the partition wall 1 that forms a partition. Specifically, in the honeycomb structure 100, the plugging portions 5 are disposed at the end portions of the gas inflow end surface plugged cells 2 b on the inflow end surface 11 of the honeycomb substrate 4. With this structure, when the exhaust gas G flows into a cell in which the plugging portion 5 is not disposed (that is, the through cell 2a), the pressure in the through cell 2a rises and a gas inflow end adjacent to the through cell 2a. The pressure in the face plugged cell 2b is relatively lower than the pressure in the through-cell 2a. For this reason, a part of the exhaust gas G passes through the porous partition wall 1 from the through cell 2a and flows into the gas inflow end face plugged cell 2b, and the exhaust gas G flowing into the gas inflow end face plugged cell 2b The gas inflow end face plugged cells 2b are discharged from the end on the side where the plugging portion 5 is not disposed (the outflow end face 12 side in the honeycomb substrate 4). Since the through cell 2a and the gas inflow end face plugged cell 2b are adjacent to each other, the exhaust gas G passes through the porous partition wall 1 positioned between the through cell 2a and the gas inflow end face plugged cell 2b. It is possible to move “from the through cell 2a to the gas inflow end face plugged cell 2b”. And since a part of exhaust gas G permeate | transmits the partition wall 1 and the particulate matter contained in the exhaust gas G accumulates on the partition wall 1 in the penetration cell 2a, a particulate matter can be collected. FIG. 7A is a schematic view showing a cross section of the first embodiment of the honeycomb structure of the present invention parallel to the direction in which the exhaust gas flows.

  In the honeycomb structure 100 of the present embodiment, the specific through-cell 2aa has two or more gas inflow end face plugged cells 2ba and 2bb in which the length of the plugged portion 5 is different in each cell 2. It is comprised so that it may adjoin. Further, in the at least two gas inflow end face plugged cells 2ba and 2bb, the plugged portions 5a and 5b are non-mirror-symmetric with respect to the adjacent specific through-cell 2aa. By configuring in this way, as shown in FIG. 7B, in the partition wall 1 in the specific through-cell 2aa, a difference can be provided in the starting point from the inflow end face 11 side where the particulate matter 13 starts to deposit. That is, in the specific through-cell 2aa, the portion of the partition wall 1 where the plugging portion 5 is disposed hardly transmits the exhaust gas G, and the portion of the partition wall 1 where the plugging portion 5 is not disposed (in other words, In other words, the particulate matter 13 starts to be deposited from the place where the plugging portion 5 is interrupted). Accordingly, the partition wall 1 separating the specific through cell 2aa and the first gas inflow end face plugged cell 2ba, and the partition wall 1 separating the specific through cell 2aa and the second gas inflow end face plugged cell 2bb. Thus, a difference can be provided at the position where the particulate matter 13 starts to be deposited. For this reason, the deposition start position of the particulate matter 13 in the vicinity of the inflow end face 11 of the honeycomb structure 100 is shifted, and the inflow end face 11 side of the specific through-cell 2aa is less likely to become narrow due to the deposition of the particulate matter 13. And if the flow path in specific penetration cell 2aa can be ensured widely, even if the flow volume of exhaust gas G increases, the pressure concerning the deposited particulate matter 13 can be controlled, and the partition of particulate matter 13 The peeling off from 1 can be prevented. Therefore, according to the honeycomb structure 100 of the present embodiment, the particulate matter 13 once collected can be effectively prevented from flowing out (in other words, blow-off). The effect of effectively suppressing such blow-off is a remarkable effect peculiar to the honeycomb structure 100 having the penetrating cell 2a and collecting the particulate matter 13 in the partition wall 1 partitioning the penetrating cell 2a. is there.

  Although illustration is omitted, in the honeycomb structure of the present embodiment, the specific through cell is disposed adjacent to the three gas inflow end face plugged cells, and the three gas inflow end face plugs are provided. The lengths of the plugged portions may be different within the stop cell. Moreover, even if the specific penetration cell is arrange | positioned so that the four gas inflow end surface plugged cells may be adjacent, and the length of the plugging part differs in the four gas inflow end surface plugged cells. Good. Thus, if the number of gas inflow end face plugged cells adjacent to the specific through cell is two or more, the number of cells that can be adjacent to the specific through cell can be increased. Moreover, in the gas inflow end face plugged cell adjacent to the specific through-cell, if the length of the plugged portion is different in the two gas inflow end face plugged cells, the length of the plugged portion is the same. There may be a plurality of gas inflow end face plugged cells. Of course, in all the gas inflow end face plugged cells adjacent to the specific through-cell, the length of the plugged portion may be different in each cell. In addition, when the specific penetration cell is arranged so as to be adjacent to three or more gas inflow end face plugged cells, the plugged portion is adjacent in at least two gas inflow end face plugged cells. It is necessary to be non-mirror image symmetric across the specific penetration cell.

  In the honeycomb structure of the present embodiment, the number of gas inflow end face plugged cells is preferably 25 to 50% with respect to the total number of cells. In other words, the number of penetrating cells is preferably 50 to 75% with respect to the number of all cells. Hereinafter, “the ratio of the number of gas inflow end face plugged cells to the number of all cells” is simply referred to as “the ratio of the number of gas inflow end face plugged cells” or “the ratio of gas inflow end face plugged cells”. Sometimes. Further, the “ratio of the number of penetrating cells with respect to the number of all cells” may be simply referred to as “number ratio of penetrating cells” or “ratio of penetrating cells”. When the ratio of the gas inflow end face plugged cells is less than 25%, the collection efficiency for collecting the particulate matter of the honeycomb structure may be lowered. If it exceeds 50%, the pressure loss of the honeycomb structure may greatly increase. The ratio of the gas inflow end face plugged cells is more preferably 35 to 50%.

  Further, in order to effectively prevent the particulate matter once collected from peeling off from the partition wall, the number of specific through cells is 50% or more with respect to the number of all through cells. Is preferred. Hereinafter, the “ratio of the number of specific through cells with respect to the number of all through cells” may be simply referred to as “number ratio of specific through cells” or “ratio of specific through cells”. If the ratio of the specific penetrating cell is less than 50%, the effect of suppressing the outflow of the particulate matter once collected may not be sufficiently exhibited. The ratio of the specific penetrating cell is more preferably 70% or more, and particularly preferably 100%. By setting the ratio of the specific penetrating cells in the numerical range as described above, the outflow of the particulate matter to the outside can be particularly effectively suppressed.

In the honeycomb structure of the present embodiment, the cell cross section perpendicular to the cell extending direction is preferably a polygon having a plurality of corners. Then, at the corner in one cell of the gas inflow end face plugged cell, the maximum value of the difference in length in the cell extending direction of the plugging portion of each corner from the exhaust gas inflow end face is 5 mm. As mentioned above, it is more preferable that it is 25 mm or less.
By configuring in this way, it is possible to secure a sufficient difference in the deposition start point of the particulate matter, and to suppress an excessive decrease in the collection efficiency of the honeycomb structure. For example, if the maximum value of the length difference in the cell extending direction of each corner plugging portion is less than 5 mm, it is not possible to sufficiently ensure the difference in the deposition start point of the particulate matter, The flow path in the specific penetration cell may be easily blocked. On the other hand, if the maximum value of the difference in length in the cell extending direction of the plugged portion at each corner exceeds 25 mm, the length of the portion where the filter function is not expressed by the plugged portion becomes too long, The collection efficiency of the honeycomb structure may be reduced, or the pressure loss of the honeycomb structure may be increased. For example, in FIG. 5, the length T1 of the plugging portion 5 at the vertex O1 and the vertex O4 of the first gas inflow end face plugged cell 2ba, the vertex O2 of the first gas inflow end face plugged cell 2ba, and It is preferable that difference T2-T1 with respect to length T2 of the plugging part 5 of the vertex O3 is 5 mm or more and 25 mm or less. More preferably, the maximum difference in the lengths of the plugged portions at the corners in the cell extending direction is 15 mm or more. Further, the maximum value of the difference in length in the cell extending direction of the plugged portion at each corner is more preferably 20 mm or less.

  In addition, at the corner in one cell of the gas inflow end face plugged cell, the length in the cell extending direction of the plugged portion at each corner is 2 mm or more and 35 mm or less starting from the exhaust gas inflow end face. Preferably there is. The length in the cell extending direction of the plugging portion at each corner is more preferably 5 mm or more and 25 mm or less. When the length in the cell extending direction of the plugging portion at each corner of the gas inlet end face plugged cell is less than 2 mm, soot is easily deposited near the inlet and flows into the gas, and the plugging depth If it is shallow, it is not preferable because the seal is easily removed. When the length in the cell extending direction of the plugged portion at each corner of the gas inflow end face plugged cell exceeds 35 mm, the length of the portion where the filter function does not appear due to the plugged portion becomes too long. In addition, the collection efficiency of the honeycomb structure may decrease, or the pressure loss of the honeycomb structure may increase.

  At one corner of the gas inflow end face plugged cell, starting from the exhaust gas inflow end face, the length of the plugging portion extending from each corner in the cell extending direction is two or less. May be the same. For example, in FIG. 5, the lengths of the plugging portions 5a at the vertex O1 and the vertex O4 of the first gas inflow end face plugged cell 2ba are the same. In FIG. 5, the lengths of the plugging portions 5b of the vertex O2 and the vertex O3 of the first gas inflow end face plugging cell 2ba are the same. By configuring in this way, the shape of the plugging portion is improved while the effects of suppressing the outflow of the collected particulate matter to the outside and the effect of suppressing clogging of the end face of the honeycomb structure as described above are well expressed. It can be relatively simple.

  In the honeycomb structure of the present embodiment, the cells formed on the honeycomb substrate include through cells, and gas inflow end face plugged cells that are plugged only by the plugging portions on the inflow end face side of the honeycomb base material. Any one of the cells is preferred. By comprising in this way, the honeycomb structure of this embodiment can be used effectively as a filter which collects particulate matter. Of course, in the honeycomb structure of the present embodiment, a part of the cells formed on the honeycomb base material may be one in which the outflow end face side of the honeycomb base material is closed by the plugging portion.

  Here, the second embodiment and the third embodiment of the honeycomb structure of the present invention will be described. FIG. 8 is an enlarged perspective view of the vicinity of the inflow end face in the second embodiment of the honeycomb structure of the present invention. FIG. 8 is an enlarged perspective view of the vicinity of the inflow end surface in the third embodiment of the honeycomb structure of the present invention. As described below, the honeycomb structure of the second embodiment is different in the length of the plugging portion in the cell extending direction at the corner portion of one of the gas inflow end face plugged cells. Is configured similarly to the honeycomb structure of the first embodiment. As shown in FIG. 8, the honeycomb structure of the second embodiment is plugged on the inflow end face 11 side of the first gas inflow end face plugged cell 2ba and the second gas inflow end face plugged cell 2bb. Stop portions 25a and 25b are provided. In the first gas inflow end face plugging cell 2ba, the length in the cell 2 extending direction of the plugging portion 25a from the inflow end face 11 is the length T3 at the vertex O1, and the length T4 at the vertex O2 and the vertex O3. The vertex O4 has a length T5. In the second gas inflow end face plugged cell 2bb, the length in the cell 2 extending direction of the plugging portion 25b from the inflow end face 11 is the length T4 at the vertex P1 and the vertex P3, and the length T5 at the vertex P2. The vertex P4 has a length T3. The plugging portion 25a and the plugging portion 25b are non-mirror image symmetric with respect to the penetrating cell 2a (specific penetrating cell 2aa).

  Next, the honeycomb structure of the third embodiment will be described. The honeycomb structure of the third embodiment also has the same structure as that of the first embodiment except that the length of the plugging portion in the corner portion in one cell of the gas inflow end face plugged cells is different. The structure is the same as that of the honeycomb structure. As shown in FIG. 9, the honeycomb structure of the third embodiment is plugged on the inflow end face 11 side of the first gas inflow end face plugged cell 2ba and the second gas inflow end face plugged cell 2bb. Stop portions 45a and 45b are provided. In the first gas inflow end face plugging cell 2ba, the length in the cell 2 extending direction of the plugging portion 45a from the inflow end face 11 is the length T7 at the vertex O1 and the vertex O2, and at the vertex O3 and the vertex O4. The length is T6. On the other hand, in the second gas inflow end face plugged cell 2bb, the length in the cell 2 extending direction of the plugged portion 45b from the inflow end face 11 is the length T6, the vertex P3, and the vertex at the vertex P1 and the vertex P2. In P4, the length is T7. The plugging portion 45a and the plugging portion 45b are non-mirror image symmetric with respect to the penetrating cell 2a (specific penetrating cell 2aa). Also in the honeycomb structures of the second embodiment and the third embodiment configured as described above, the flow path in the specific through-cell is difficult to close. Note that the aspect of the plugged portion that is non-mirror image symmetric across the specific penetration cell is not limited to the honeycomb structure of the first to third embodiments described so far, and can be variously changed. It is.

  Further, as another embodiment in which the plugging portion is non-mirror image symmetric across the adjacent through-cells, in the two gas inflow end faced plugged cells in a positional relationship where the symmetry line is 45 °, Each plugged portion may be non-mirror image symmetric with respect to an adjacent specific through-cell. Further, when the cell shape in the cross section perpendicular to the cell extending direction is a hexagon, in each of the two gas inflow end faced plugged cells having a positional relationship with the symmetry line of 60 °, each plugged portion However, it may be non-mirror image symmetric with respect to adjacent specific through-cells. For example, when the shape of the cell is a hexagon, the arrangement shown in FIGS. 10A and 10B can be given as an arrangement of the specific through cell and the gas inflow end face plugged cell. 10A and 10B are schematic views illustrating another example of the arrangement of the specific through-cells and the gas inflow end face plugged cells. 10A and 10B, the specific through cell 32aa as the through cell 32a is arranged with the six cells 32 and the partition wall 31 separated from each other. 10A and 10B, the six cells 32 adjacent to one specific through-cell 32aa are arranged around the specific through-cell 32aa with the through-cell 32a and the gas inflow end face plugged cell 32b. They are arranged so as to be arranged alternately. In FIG. 10A, the plugged portion is non-mirror-symmetric in the two gas inflow end face plugged cells 32ba and 32bb which are in a positional relationship with the symmetric line being 60 ° with respect to one specific through cell 32aa. It has become. Further, in FIG. 10B, the plugged portion is not plugged in the three gas inflow end faced plugged cells 32ba, 32bb, 32bc that are in a positional relationship with a specific line of 60 ° with respect to one specific through cell 32aa. Mirror image symmetry.

  The shape of the cells of the honeycomb substrate is not particularly limited, but is preferably a polygon, such as a triangle, a quadrangle, a pentagon, a hexagon, an octagon, a circle, or an ellipse in a cross section perpendicular to the cell extending direction. Other irregular shapes may also be used.

  The porosity of the partition walls is preferably 40 to 80%, and more preferably 45 to 67%. If it is less than 40%, the collection performance may be remarkably deteriorated. If it is more than 80%, the strength of the honeycomb base material is lowered, so that it becomes difficult to perform canning (being damaged when stored in a storage container). Sometimes. Furthermore, when the porosity is 45 to 67%, the collection efficiency of the honeycomb structure (100 × [mass of collected particulate matter] / [mass of inflowing particulate matter]) is good as a filter. Can be a value. Further, when the porosity is 45 to 67%, the strength of the honeycomb structure is improved and canning is facilitated. The porosity of the partition wall is a value measured with a mercury porosimeter.

  The thickness of the partition wall is preferably 150 to 410 μm, and more preferably 200 to 360 μm. If it is thinner than 150 μm, the strength of the honeycomb substrate may be lowered. If it is thicker than 410 μm, the collection performance may decrease and the pressure loss may increase. In addition, when treating exhaust gas discharged from a diesel engine, the amount of PM in the exhaust gas discharged from the diesel engine is relatively large, and thus there is a general tendency to reduce the number of cells (reduce the cell density). . Therefore, it is preferable that the thickness of the partition wall 1 be 200 to 360 μm in order to improve the balance between strength and collection performance. In addition, when processing exhaust gas discharged from a gasoline engine, the amount of PM in the exhaust gas discharged from the gasoline engine is relatively small, and thus usually tends to increase the number of cells (increase the cell density). . Therefore, it is preferable to set the partition wall thickness to 150 to 310 μm in order to improve the balance between strength and collection performance. The thickness of the partition wall is a value measured by a method of observing a cross section in the axial direction of the honeycomb substrate with a microscope.

The cell density of the honeycomb substrate (the number of cells per unit area in the cross section perpendicular to the cell extending direction of the honeycomb substrate) is preferably 15 to 62 cells / cm ² . If it is less than 15 cells / cm ² , the collection performance may be lowered. If it is larger than 62 cells / cm ² , PM is deposited near the inflow end face of the honeycomb substrate, and the cells are blocked by PM, so that the pressure loss may increase. Moreover, when processing the exhaust gas discharged | emitted from a diesel engine, it is still more preferable that it is 15-47 cells / cm < ² >. When it is less than 15 cells / cm ² , the collection performance may be lowered. If it is greater than 47 cells / cm ² , the pressure loss may increase. Moreover, when processing the exhaust gas discharged | emitted from a gasoline engine, it is still more preferable that it is 31-62 cells / cm < ² >. Since the exhaust gas discharged from a gasoline engine has a small amount of PM, the risk of clogging the cells is low, so the cell density can be increased, and the collection performance can be increased by increasing the cell density. it can. In addition, since the cell is difficult to block, continuous reproduction is also easy. If it is less than 31 cells / cm ² , the collection performance may be lowered, and if it is more than 62 cells / cm ² , the pressure loss during PM collection may be increased.

  The average pore diameter of the partition walls is preferably 80 μm or less, more preferably 0.1 to 80 μm, still more preferably 1 to 80 μm, and particularly preferably 5 to 25 μm. If it is larger than 80 μm, the honeycomb base material becomes brittle and easily lost, and particulate matter may enter the partition walls, resulting in depth filtration. Such a partition wall having a large average pore diameter is not preferable because the particulate matter collecting performance tends to be lowered with PM collection. Moreover, it is not preferable that the average pore diameter of the partition walls is smaller than 0.1 μm because the pressure loss increases even when the particulate matter is little deposited. Furthermore, if the average pore diameter of the partition walls is smaller than 5 μm, the wall permeation resistance (resistance when exhaust gas permeates through the partition walls) when an oxidation catalyst is supported may increase. Moreover, when the average pore diameter of a partition is larger than 25 micrometers, ash (Ash) accumulates inside a partition and possibility that a collection performance will deteriorate after long-term use may become high. The average pore diameter of the partition wall is a value measured with a mercury porosimeter.

  Although the thickness of the outer peripheral wall 3 of the honeycomb base material 4 is not specifically limited, 0.5-6 mm is preferable. If it is thinner than 0.5 mm, cells near the outer periphery are likely to be chipped, and the strength may be reduced. If it is thicker than 6 mm, the pressure loss may increase.

  The shape of the honeycomb substrate (in other words, the shape of the honeycomb structure) is not particularly limited, but a cylindrical shape, an elliptical columnar shape on the bottom, a polygonal columnar shape such as a square, pentagon, hexagon, etc. on the bottom Is preferred. The honeycomb structure preferably has a column shape with the cell extending direction as the central axis direction. Further, the size of the honeycomb substrate (in other words, honeycomb structure) is not particularly limited, but the length in the cell extending direction is preferably 15 to 200 mm. When the length of the honeycomb substrate is in such a range, the honeycomb structure can treat the exhaust gas with excellent collection performance without increasing the pressure loss. When it is shorter than 15 mm, the collection performance may be deteriorated. On the other hand, when the length is longer than 200 mm, the improvement in the collection performance cannot be expected so much, but the pressure loss may increase. Considering the balance between collection performance and pressure loss, the length of the honeycomb substrate is more preferably 50 to 153 mm. This is particularly effective when a plurality of honeycomb structures are arranged in series in the storage container. For example, when the outer shape of the honeycomb substrate (in other words, the honeycomb structure) is a columnar shape, the bottom surface (end surface) preferably has a diameter of 80 to 400 mm. The diameter of the bottom surface of the honeycomb base material is appropriately selected within the above range according to the engine displacement and output.

  The partition walls and the outer peripheral wall of the honeycomb base material are preferably composed mainly of ceramic. Specific examples of the material for the partition wall and the outer peripheral wall include silicon carbide, silicon-silicon carbide composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite composite material, lithium aluminum silicate, and aluminum titanate. It is preferably at least one selected from the group consisting of Among these, silicon carbide having excellent thermal conductivity and cordierite having a small thermal expansion coefficient and excellent thermal shock resistance are preferable. In a normal DPF, it is necessary to increase the PM deposition amount and lengthen the regeneration interval. Therefore, a material having a large heat capacity such as silicon carbide is preferable. However, in the present invention, the heat capacity that facilitates continuous regeneration is relatively small. Cordierite is particularly preferred. The material of the partition wall and the outer peripheral wall is preferably the same, but may be different. In addition, the phrase “mainly composed of ceramic” means that 90% by mass or more of ceramic is contained.

  As shown in FIGS. 1 to 6, in the honeycomb structure 100 of the present embodiment, the plugging portions 5 are formed so as to close the end portions of some cells 2 on the inflow end face 11 side of the honeycomb substrate 4. It is arranged. In the honeycomb structure 100 of the present embodiment, a part of the cells (gas inflow end surface plugged cells 2b) in which the plugging portions 5 are disposed and the remaining cells (penetration) in which the plugging portions are not disposed. The cells 2a) are arranged adjacent to each other. Further, the gas inflow end face plugged cells 2b and the through cells 2a are alternately arranged, and in the inflow end face 11 of the honeycomb substrate 4, the openings of the through cells 2a and the end portions of the gas inflow end face plugged cells 2b. It is preferable that a checkered pattern is formed by the plugged portions disposed in the. The material of the plugging portion 5 is preferably the same as the material of the partition walls 1 of the honeycomb substrate 4.

  The honeycomb structure of the present embodiment may be one in which an oxidation catalyst is supported on at least a part of the partition walls. More specifically, it is preferable that the catalyst is supported on the partition walls of the honeycomb substrate constituting the honeycomb structure. The supported amount of the catalyst per unit volume is preferably 0.1 to 150 g / liter, and more preferably 10 to 80 g / liter. “G / liter” indicates the number of grams (g) of catalyst per liter of honeycomb structure. If the amount is less than 0.1 g / liter, the catalytic effect may be difficult to be exhibited. When the amount is more than 150 g / liter, the pores of the partition walls are blocked, resulting in an increase in pressure loss and a significant reduction in collection efficiency. In the case of an oxidation catalyst that forms a washcoat layer, the supported amount of catalyst per unit volume is preferably 10 to 150 g / liter. If the amount of catalyst supported is less than 10 g / liter, it may be difficult to form a washcoat layer.

  Examples of the oxidation catalyst include those containing noble metals, and specifically, those containing at least one selected from the group consisting of Pt, Rh and Pd are preferable. The total amount of the noble metal is preferably 0.1 to 5 g / liter per unit volume of the honeycomb structure.

(2) Manufacturing method of honeycomb structure:
An embodiment of a method for manufacturing a honeycomb structure of the present invention will be described. The method for manufacturing a honeycomb structure of the present embodiment includes a honeycomb formed body forming step, a film disposing step, and a plugging portion forming step. The honeycomb formed body forming step is a step of forming a honeycomb formed body having partition walls for partitioning and forming a plurality of cells serving as fluid flow paths extending from one end face to the other end face by extruding a forming raw material. . The film disposing step is a step of disposing a film covering the cell opening on one end surface of the obtained honeycomb formed body or the honeycomb fired body obtained by firing the honeycomb formed body. The plugging portion forming step is a step of forming plugging portions in at least two cells to be plugged adjacent to cells that should not be plugged. And in the manufacturing method of the honeycomb structure of the present embodiment, the plugging portion forming step includes the following perforated portion forming step and the plugging material supply step. In the perforated part forming step, the perforated part is formed in a part of the film covering each cell to be plugged, and the center of gravity of the perforated part is the center of gravity of the cell opening of the cell to be plugged. It is off. In the plugging material supply step, by supplying the plugging material from the surface on which the film is disposed, the length in the cell extending direction of the plugging portion from the supply surface of the plugging material is equal to one. Different plugging portions are formed in one cell.

  According to the method for manufacturing a honeycomb structure of the present embodiment, a honeycomb structure 100 as shown in FIGS. 1 to 6 can be easily manufactured. Hereinafter, the manufacturing method of the honeycomb structure of the present embodiment will be described in more detail for each process.

(2-1) Honeycomb molded body forming step:
In the honeycomb formed body forming step, a forming raw material is formed by extruding a forming raw material to form a honeycomb formed body having partition walls that form a plurality of cells that serve as fluid flow paths extending from one end face to the other end face. is there. The forming raw material is preferably a ceramic raw material added with a dispersion medium and an additive. Examples of the additive include an organic binder, a pore former, and a surfactant. Examples of the dispersion medium include water. In the honeycomb formed body forming step, it is preferable to knead the forming raw material into clay.

  The ceramic raw material is selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite forming raw material, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. At least one kind is preferred. Among these, a cordierite-forming raw material having a small thermal expansion coefficient and excellent thermal shock resistance is preferable. Examples of the additive include an organic binder, a pore former, and a surfactant. Examples of the dispersion medium include water.

  The method of kneading the forming raw material to form the kneaded material is not particularly limited, and examples thereof include a method using a kneader, a vacuum kneader or the like.

  It is preferable to extrude the kneaded material made of such a forming raw material to form a honeycomb formed body having partition walls that form a plurality of cells serving as fluid flow paths extending from one end face to the other end face. . Extrusion can be performed using a die having a desired cell shape, partition wall thickness, and cell density. As the material of the die, a cemented carbide which does not easily wear is preferable. The honeycomb formed body forming step can be performed according to the step of forming a honeycomb formed body in a conventionally known method for manufacturing a honeycomb structure.

(2-2) Film disposing step:
A film | membrane arrangement | positioning process is a process of arrange | positioning the film which covers a cell opening part to one end surface in the obtained honeycomb molded object. In addition, before performing a film | membrane arrangement | positioning process, you may dry the obtained honeycomb molded object. Further, the film disposing step may be performed on a honeycomb fired body obtained by firing a honeycomb formed body or a honeycomb dried body obtained by drying the honeycomb formed body. For example, the film disposing step is a step of disposing a film 75 covering the cell opening of the cell 2 on one end face 71 of the honeycomb formed body 600 as shown in FIGS. 11A and 11B. In this film disposing step, the cell opening of both the cell to be a through cell (that is, the cell 62a that should not be plugged) and the cell to be a gas inflow end face plugged cell (cell 62b to be plugged). The part is closed by the film 75. FIG. 11A is a diagram for explaining a film disposing step in one embodiment of a method for manufacturing a honeycomb structured body of the present invention, and shows a state before disposing a film on one end face of the honeycomb formed body. FIG. FIG. 11B is a diagram for explaining a film disposing step in an embodiment of the method for manufacturing a honeycomb structured body of the present invention, and shows a state after a film is disposed on one end face of the honeycomb formed body. FIG. 11A and 11B, reference numeral 61 indicates “partition walls” of the honeycomb formed body 600, and reference numeral 62 indicates “cells” partitioned by the partition walls 61.

  As a film covering the cell opening, for example, a polyester film can be used. An adhesive can be applied to one side of the film and adhered to the end face of the honeycomb formed body.

(2-3) Plugging portion forming step:
The plugging portion forming step is a step of forming plugging portions in at least two cells to be plugged adjacent to cells that should not be plugged. The plugging portion forming step includes the following perforated portion forming step and a plugging material supply step. In the perforated part forming step, the perforated part is formed in a part of the film covering each cell to be plugged, and the center of gravity of the perforated part is the center of gravity of the cell opening of the cell to be plugged. It is off. In the plugging material supply step, by supplying the plugging material from the surface on which the film is disposed, the length in the cell extending direction of the plugging portion from the supply surface of the plugging material is equal to one. Different plugging portions are formed in one cell. Here, the cell which should not be plugged is a cell used as a penetration cell in the manufactured honeycomb structure. The cell to be plugged is a cell that becomes a gas inflow end face plugged cell in the manufactured honeycomb structure.

  That is, in the plugging portion forming step, first, as shown in FIG. 11C, the perforated portion 76 is formed in a part of the film 75 covering each of the cells 62b to be plugged. At this time, the perforated part 76 is formed so that the center of gravity of the perforated part 76 is shifted from the center of gravity of the cell opening of the cell 62b to be plugged. FIG. 11C is a diagram illustrating a plugging portion forming step in an embodiment of the method for manufacturing a honeycomb structure of the present invention, and is an explanatory diagram illustrating a step of forming a perforated portion in a part of a film.

  Next, as shown in FIGS. 11D and 11E, a plugging material 81 is supplied from the surface on which the film 75 is disposed. 11D and 11E, the plugging material 81 is placed on a plate-shaped plugging material mounting table 82. Examples of the plugging material 81 include a slurry material containing a ceramic raw material, water or alcohol, and an organic binder. The ceramic raw material is preferably the same as the ceramic raw material used as the raw material for the honeycomb formed body. The ceramic raw material is preferably 68 to 90% by mass of the whole plugging material. The plugging material may be stored in a bottomed cylindrical storage container.

  As shown in FIG. 11E, the plugging material 81 passes through the perforated portion 76 of the film 75 by pressing the one end surface 71 on which the film 75 of the honeycomb formed body 600 is disposed against the plugging material 81. Thus, the inside of the cell 62b to be plugged is filled. As described above, the perforated part 76 is perforated so that the center of gravity of the perforated part 76 deviates from the center of gravity of the cell opening of the cell 62b to be plugged. When filling, the filling amount increases at a location deviated from the center of gravity. For this reason, plugging portions having different lengths from the supply surface of the plugging material 81 in one cell can be formed. The above-mentioned “length of the plugged portion” refers to “the length of the plugged portion in the cell extending direction”. Here, FIG. 11D and FIG. 11E are diagrams for explaining a plugging portion forming step in one embodiment of the method for manufacturing a honeycomb structure of the present invention, and an explanation showing a step of forming the plugging portion. FIG.

  In the perforated part forming step, the cell opening is a polygon having a plurality of corners, and the center of gravity of the perforated part is shifted on a straight line passing through the center of gravity of the cell opening and the corner of the cell opening. Is preferred. Further, in the perforated part forming step, the center of gravity of the perforated part may be shifted on a perpendicular drawn from the center of gravity of the cell opening to the partition wall. With this configuration, in the step of forming the plugging portion, the length of the plugging portion in the cell extending direction from the supply surface of the plugging material is different in one cell. It becomes easy to form a stop.

  Further, in the perforated part forming step, the center of gravity of the perforated part for perforating the film covering each cell to be plugged becomes non-symmetrical across the film covering the cell not to be plugged. Thus, it is preferable to form a perforated part. With such a configuration, the two non-pluggable cells arranged between the cells that should not be plugged are non-mirror-symmetric with respect to the cells that should not be plugged. In addition, a plugging material can be filled. Also, the local length of the plugging material filled in one cell can be controlled by adjusting the size and position of the perforated part opened in the film and the degree of deviation from the center of gravity of the cell opening. Can do.

  The viscosity of the plugging material is preferably 100 to 400 Pa · s. The viscosity of the plugging material is a value measured at a rotation speed of 30 rpm with a rotary viscometer at a temperature of 30 ° C. When the viscosity of the plugging material is less than 100 Pa · s, the length in the cell extending direction of the plugging portion from the supply surface of the plugging material is easily leveled in one cell. Become. On the other hand, when the viscosity of the plugging material exceeds 400 Pa · s, it is difficult to supply the plugging material from the perforated portion of the film, and it may be difficult to form the plugged portion.

  In the method for manufacturing a honeycomb structured body of the present embodiment, a honeycomb formed body in which the plugging material is filled in the cell opening may be fired. The firing temperature can be appropriately determined depending on the material of the honeycomb formed body. For example, when the material of the honeycomb formed body is cordierite, the firing temperature is preferably 1380 to 1450 ° C, and more preferably 1400 to 1440 ° C. The firing time is preferably about 3 to 10 hours. Further, the honeycomb formed body may be dried before firing. As described above, the honeycomb structure of the present embodiment can be manufactured.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

Example 1
(Honeycomb structure)
First, 13 parts by mass of a pore former, 35 parts by mass of a dispersion medium, 6 parts by mass of an organic binder, and 0.5 parts by mass of a dispersant are added to 100 parts by mass of a cordierite forming raw material, and mixed and kneaded. A clay was prepared. As the cordierite forming raw material, alumina, aluminum hydroxide, kaolin, talc, and silica were used. Water was used as the dispersion medium, coke having an average particle diameter of 1 to 10 μm was used as the pore former, hydroxypropylmethylcellulose was used as the organic binder, and ethylene glycol was used as the dispersant.

  Next, the kneaded material was extruded using a predetermined mold to obtain a honeycomb formed body having a square cell shape and a columnar overall shape.

  Next, the honeycomb formed body was dried with a microwave dryer and further completely dried with a hot air dryer, and then both end faces of the honeycomb formed body were cut and adjusted to a predetermined size. Next, a film was covered so as to cover the entire area of one end face of the honeycomb formed body, and a perforated part was opened at a position corresponding to the cell opening of the cell to be a gas inflow end face plugged cell. At this time, the perforated part was formed such that the center of gravity of the perforated part was shifted from the center of gravity of the cell opening of the cell to be plugged that would become the gas inflow end faced plugged cell. As shown in FIG. 12D, the size of the perforated part 96 is a circle having a radius of 0.27 mm, and the amount of deviation between the center of gravity 97 of the perforated part 96 and the center of gravity 93 of the cell opening 92 of the cell to be plugged is 128D was 0.28 mm to the left and 0.28 mm to the bottom. FIG. 12D is a schematic diagram for explaining a perforation position of a perforation part in the example.

Next, by immersing the end portion of the honeycomb formed body on which the film is applied into a slurry-like plugging material containing a cordierite forming raw material, predetermined cells (masks are applied to the exhaust gas inflow end surface). No cell) was filled with the plugging material. Thus, the honeycomb structure of Example 1 was produced. The honeycomb substrate of the obtained honeycomb structure had a cylindrical shape with a diameter of a cross section perpendicular to the central axis of 143.8 mm and a length in the central axis direction of 101.6 mm. The partition wall thickness was 305 μm, and the cell density was 46.5 cells / cm ² . The shape of the cell was a square. Table 1 shows the honeycomb substrate diameter (mm) and length (mm), partition wall thickness (mm), cell density (cells / cm ² ), and cell shape.

  In the honeycomb structure of Example 1, the ratio of the through cells was 50%, and the ratio of the gas inflow end face plugged cells was 50%. That is, in the honeycomb structure of Example 1, the ratio of the number of cells in which the plugging portions are disposed on at least one of the exhaust gas inflow end surface or the exhaust gas outflow end surface is 50 with respect to the total number of cells. %. Hereinafter, with respect to the number of all cells, the ratio of the number of cells in which plugging portions are disposed on at least one of the exhaust gas inflow end face or the exhaust gas outflow end face is expressed as “the ratio of plugged cells (%). " Table 2 shows the ratio (%) of the plugged cells. Moreover, in the honeycomb structure of Example 1, all the gas inflow end face plugged cells have different lengths in the cell extending direction of the plugging portion from the exhaust gas inflow end face within one cell. Met. In this embodiment, a gas inflow end face plugged cell having a different length in the cell extending direction from the exhaust gas inflow end face in one cell is referred to as a “specific plugged cell”. . In the column “Ratio of specific plugged cells” in Table 2, the ratio of the number of specific plugged cells to the total number of gas inflow end faceted plugged cells is shown. In the honeycomb structure of Example 1, the ratio of the specific plugged cells is 100%.

  Further, in the column of “plugging pattern” in Table 2, modes on the inflow end surface and the outflow end surface of the honeycomb structure are shown. In the column “ratio (%)” of “inflow end face” in Table 2, the ratio of cells plugged at the inflow end face with respect to all cells is described. In the column of “pattern” of “inflow end face” in Table 2, the pattern of the plugged portions of the cells (here, the gas inflow end face plugged cells) subjected to the plugging is shown as A to C. Classify into 3 patterns and write the corresponding pattern. In the “pattern” column of “inflow end face”, “none” means that no plugging portion is arranged on the inflow end face.

  In the pattern indicated by “A”, as shown in FIG. 12A, the length of the plugging portion cell extending from the exhaust gas inflow end face is constant in one gas inflow end face plugged cell, Such gas inflow end face plugged cells are a pattern arranged in a staggered manner on the exhaust gas inflow end face. In the case of the pattern A, as shown in FIG. 12E, the piercing portion 96 was formed such that the centroid 97 of the piercing portion 96 and the centroid 93 of the cell opening 92 of the cell to be plugged overlap. FIG. 12E is a schematic diagram for explaining a perforation position of a perforation part in the example.

  As shown in FIG. 12B, the pattern indicated by “B” has different lengths in the direction in which the cells of the plugging portion extend from the exhaust gas inflow end face in one gas inflow end face plugged cell. The length of the plugging portion in the cell extending direction has two types of lengths, with two apexes adjacent to each other at the four apexes of the cell. In the pattern indicated by “B”, the plugged portions are inverted 180 ° around the center of gravity of the cell opening in the two gas inflow end faced plugged cells facing each other. The two gas inflow end face plugged cells facing each other are non-mirror image symmetric with respect to the adjacent through cell. In the case of the pattern B, as shown in FIG. 12F, the size of the perforated portion 96 is an ellipse having a short axis length of 0.28 mm, the center of gravity 97 of the perforated portion 96, and the cell to be plugged. The amount of deviation of the cell opening 92 from the center of gravity 93 was 0.28 mm below the plane of FIG. 12F. FIG. 12F is a schematic diagram for explaining a perforation position of a perforation part in the example.

  As shown in FIG. 12C, the pattern indicated by “C” has different lengths in the cell extending direction of the plugging portion from the exhaust gas inflow end face in one gas inflow end face plugged cell. The length of the plugging portion in the cell extending direction has three types of length at the four apexes of the cell, and the length of the plugging portion is the same at one pair of two opposing vertices. However, the lengths of the plugging portions are different at another pair of opposing vertices. In the pattern indicated by “C”, such gas inflow end face plugged cells are arranged in a staggered manner on the exhaust gas inflow end face. The two gas inflow end face plugged cells facing each other are non-mirror image symmetric with respect to the adjacent through cell. In the case of Pattern C, a perforated part was formed at a position as shown in FIG. 12D.

  Table 2 shows “maximum plugging depth in one cell”, “minimum plugging depth in one cell”, and “difference in plugging depth in one cell”. “Maximum plugging depth in one cell” means that the length of the plugging portion in the cell extending direction in the patterns of FIGS. 12B and 12C is the length at the longest vertex of the four vertexes of the cell. That is. The “minimum plugging depth in one cell” is the length of the plugging portion in the cell extending direction in the patterns of FIGS. 12B and 12C, with the length at the shortest vertex of the four vertices of the cell. That is. The “difference in plugging depth in one cell” is a value obtained by subtracting “minimum plugging depth in one cell” from “maximum plugging depth in one cell”.

  The resulting honeycomb structure was evaluated for “pressure loss”, “collection efficiency”, “soot clogging”, and “blow-off” by the following methods. Moreover, comprehensive evaluation was performed based on the evaluation results of “pressure loss”, “collection efficiency”, “soot clogging”, and “blow-off”. The results are shown in Table 3. In the comprehensive evaluation, in the evaluation results of “collection efficiency”, “soot clogging”, and “blow-off”, when there is no evaluation D, it is “pass”, and the case where there is one or more evaluation D is “ “Fail”.

(Pressure loss)
Exhaust gas discharged from a diesel engine (3.0 liters, direct injection common rail, in-line 6 cylinders) is caused to flow into the honeycomb structure so that the amount of soot deposition relative to the volume of the honeycomb structure becomes 4 g / L. Soot is collected by the partition walls of the honeycomb structure. Then, with the soot accumulation amount of 4 g / L, 200 ° C. engine exhaust gas was introduced at a flow rate of 3.0 Nm ³ / min to measure the pressure on the inflow end face side and the outflow end face side of the honeycomb structure. Then, the pressure loss (kPa) is obtained by calculating the pressure difference.
Evaluation A: Evaluation A is a case where the pressure loss is 10.0 kPa or less. In the case of evaluation A, the evaluation of pressure loss is “excellent”.
Evaluation B: The case where pressure loss exceeds 10.0 kPa and is 17.5 kPa or less is set as evaluation B. In the case of evaluation B, the evaluation of pressure loss is “good”.
Evaluation C: The case where pressure loss exceeds 17.5 kPa is set as evaluation C. In the case of evaluation C, the evaluation of pressure loss is “OK”.

(Collection efficiency)
Soot is generated using a burner that uses light oil as fuel. A predetermined amount of air is mixed with the combustion gas so that the flow rate of the entire gas is 1.5 Nm ³ / min, and the obtained mixed gas is introduced into the honeycomb structure. The temperature of the mixed gas is 200 ° C. The concentration of the particulate matter in the mixed gas is set to 4 g / hour. The exhaust gas is sampled for about 2 minutes by a vacuum pump from sampling pipes provided on the upstream side and downstream side of the honeycomb structure. Then, when sampling the exhaust gas, PM is collected on the filter paper by passing the exhaust gas through a holder in which the filter paper is set. In addition, the mass of the filter paper is measured in advance. The mass of PM in the exhaust gas sampled from the upstream side of the honeycomb structure (the mass of PM collected on the filter paper) and the mass of PM in the exhaust gas sampled from the downstream side of the honeycomb structure (collected on the filter paper) From the PM mass, the collection efficiency (%) is calculated. Specifically, the collection efficiency (%) at 120 minutes from the start of measurement is obtained by the following formula (1).
Collection efficiency (%) = {(PM mass A−PM mass B) / PM mass A} × 100 (1)
(However, in the above formula (1), “PM mass A” represents the mass (g) of PM collected on the filter paper from the upstream side of the honeycomb structure. “PM mass B” represents the honeycomb structure. (The mass (g) of PM collected on the filter paper from the downstream side is shown.)

From the value of the collection efficiency (%) measured by the method described above, the collection efficiency was evaluated according to the following criteria.
Evaluation A: The case where the collection efficiency exceeds 50% is set as evaluation A. In the case of evaluation A, the evaluation of the collection efficiency is “excellent”.
Evaluation B: The case where collection efficiency exceeds 35% and is 50% or less is set as evaluation B. In the case of evaluation B, it is set as "good" about evaluation of collection efficiency.
Evaluation C: The case where the collection efficiency exceeds 20% and is 35% or less is set as evaluation C. In the case of the evaluation C, the evaluation of the collection efficiency is “OK”.
Evaluation D: Evaluation D is a case where the collection efficiency is 20% or less. In the case of the evaluation D, the collection efficiency is not evaluated.

(Soot clogging)
Soot is generated using a burner that uses light oil as fuel. A predetermined amount of air is mixed with the combustion gas so that the flow rate of the entire gas is 1.5 Nm ³ / min, and the obtained mixed gas is introduced into the honeycomb structure. The temperature of the mixed gas is 200 ° C. The concentration of the particulate matter in the mixed gas is set to 4 g / hour. The gas thus set is allowed to flow into the honeycomb structure for 24 hours, and the soot clogging (%) is obtained by the following equation (2).
Total opening area of through holes before soot deposition (S1)
Total opening area of through holes after soot deposition (S2)
Soot clogging (%) = (S1-S2) / (S1) (2)

From the value of the soot clogging (%) measured by the method described above, the soot clogging was evaluated according to the following criteria.
Evaluation A: A case where the soot clogging is less than 25% is defined as an evaluation A. In the case of evaluation A, it is set as “excellent” regarding the evaluation of the clogging.
Evaluation B: The case where the soot clogging is 25% or more and less than 50% is defined as evaluation B. In the case of the evaluation B, the evaluation of the soot clogging is “good”.
Evaluation C: The case where the soot clogging is 50% or more and less than 75% is defined as evaluation C. In the case of evaluation C, the evaluation of soot clogging is “OK”.
Evaluation D: Evaluation D is a case where the soot clogging is 75% or more. In the case of evaluation D, it is not possible to evaluate the soot clogging.

(Blow-off)
Exhaust gas discharged from a diesel engine (3.0 liters, direct injection common rail, in-line 6 cylinders) is caused to flow into the honeycomb structure to deposit 10.0 g / L of soot on the honeycomb structure. Next, an idling operation was performed after the engine was started, and after 5 seconds, the engine was operated for 2 minutes at a rotation speed of 2000 rpm and a torque of 178 N · m. After the start of operation, the amount of soot in the gas discharged from the outflow end face of the honeycomb structure is measured with a soot sensor manufactured by AVL. The maximum value measured by the soot sensor is taken as the blow-off amount (mg / m ³ ). From the measurement results of blow-off, blow-off was evaluated according to the following criteria.
Evaluation A: The case where the amount of leakage of soot is 200 mg / m ³ or less is set as evaluation A. In the case of evaluation A, the evaluation of blow-off is “excellent”.
Evaluation B: The case where the amount of leakage of soot exceeds 200 mg / m ³ and is 500 mg / m ³ or less is set as evaluation B. In the case of evaluation B, the evaluation of blow-off is “good”.
Evaluation C: The case where the leakage amount of soot exceeds 500 mg / m ³ and is 800 mg / m ³ or less is set as evaluation C. In the case of evaluation C, the blow-off evaluation is “OK”.
Evaluation D: Evaluation D is a case where the amount of soot leakage exceeds 800 mg / m ³ . In the case of evaluation D, the blow-off evaluation is not possible.

(Examples 2-19, Comparative Examples 1-3)
A honeycomb structure was manufactured in the same manner as in Example 1 except that the configuration of the honeycomb substrate and the arrangement of the cells to be plugged were changed as shown in Tables 1 and 2. The obtained honeycomb structure was evaluated for “pressure loss”, “collection efficiency”, “soot clogging”, and “blow-off” in the same manner as in Example 1. Moreover, comprehensive evaluation was performed based on the evaluation results of “pressure loss”, “collection efficiency”, “soot clogging”, and “blow-off”. The results are shown in Table 3.

  In Example 18, the ratio of plugged cells is 50%, and the ratio of specific plugged cells is 50%. That is, in Example 18, the ratio of the specific plugged cells is 25% with respect to all the cells, and the ratio of the plugged cells other than the specific plugged cells is 25%. In Example 18, 25% of the specific plugged cells are arranged to be the pattern C, and the plugged cells other than the 25% of the specific plugged cells are arranged to be the pattern A. Has been.

  In Example 19, the percentage of plugged cells is 50%, and the percentage of specific plugged cells is 70%. That is, in Example 19, the ratio of the specific plugged cells is 35% with respect to all the cells, and the ratio of the plugged cells other than the specific plugged cells is 15%. In Example 19, 35% of the specific plugged cells are arranged to be the pattern C, and the plugged cells other than the 15% of the specific plugged cells are arranged to be the pattern A. Has been.

  In Comparative Example 1, the percentage of plugged cells is 100%. In Comparative Example 1, the ratio of the specific plugged cells is 0%. That is, in Comparative Example 1, the length of the plugging portion in the cell extending direction is constant in one cell. In Comparative Example 1, the cell openings are alternately plugged at the inflow end surface and the outflow end surface of the honeycomb structure. In Comparative Example 2, the percentage of plugged cells is 0%. In Comparative Example 3, the percentage of plugged cells is 50%. In Comparative Example 3, the ratio of the specific plugged cells is 0%.

(result)
As shown in Table 3, the honeycomb structures of Examples 1 to 19 can all obtain good results in the evaluation of “pressure loss”, “collection efficiency”, “soot clogging”, and “blow off”. did it. The honeycomb structure of Comparative Example 1 had no through-cells and was provided with 50% plugged portions on the inflow end surface and the outflow end surface, so that the pressure loss was large and the “pressure loss” Evaluation was unsuccessful. The honeycomb structure of Comparative Example 2 had a significantly low collection efficiency because there were no plugged cells. In the honeycomb structure of Comparative Example 3, since there are no specific plugged cells, the particulate matter concentrates and accumulates at portions where the plugging portion on the inflow end face side is interrupted, so that clogging and blow-off easily occur. It was a thing. For this reason, the honeycomb structure of Comparative Example 2 failed in the evaluation of “soot clogging” and “blow-off”.

  The honeycomb structure of the present invention can be used as a filter for purifying exhaust gas. The method for manufacturing a honeycomb structure of the present invention can be used as a method for manufacturing the honeycomb structure of the present invention.

1, 31: partition wall, 2, 32: cell, 2a, 32a: penetration cell, 2aa, 32aa: specific penetration cell, 2b, 2ba, 2bb, 32b, 32ba, 32bb, 32bc: gas inflow end face plugged cell, 3 : Outer peripheral wall, 4: honeycomb substrate, 5: plugging portion, 11: inflow end surface, 12: outflow end surface, 13: particulate matter, 61: partition walls, 62: cell, 62a: cell not to be plugged 62b: cell to be plugged, 71: one end face, 75: film, 76: perforated part, 81: plugging material, 82: plugging material mounting table, 92: cell opening, 93: center of gravity (Centroid of cell opening), 96: perforated part, 97: center of gravity (centroid of perforated part), 100, 800: honeycomb structure, 600: honeycomb formed body, 801: partition wall, 802: cell, 802a: penetrating cell, 802b: Gas inflow end face plugged cell 803: outer peripheral wall, 804: honeycomb base material, 805: plugging portion, 813: particulate matter, G: exhaust gas, O1 to O4, P1 to P4: apex, T1 to T7: length.

Claims (13)

A honeycomb base material having a porous partition wall that extends from the exhaust gas inflow end surface to the exhaust gas outflow end surface and defines a plurality of cells to be fluid flow paths,
The cell includes a penetrating cell penetrating from the exhaust gas inflow end surface to the exhaust gas outflow end surface, and a gas inflow end surface plugged cell in which the exhaust gas inflow end surface is blocked by a plugging portion,
At least one of the through-cells is disposed adjacent to at least two of the gas inflow end face plugged cells;
In each of the at least two gas inflow end face plugged cells adjacent to the through cell, the length of the plug extending portion from the exhaust gas inflow end face in the cell extending direction is different in each cell. And in the at least two gas inflow end face plugged cells, the plugged portion is non-mirror image symmetric with respect to the adjacent through cell.   The cell cross section perpendicular to the cell extending direction is a polygon having a plurality of corners, and the corners in one cell of the gas inflow end face plugged cells, starting from the exhaust gas inflow end face, The honeycomb structure according to claim 1, wherein a maximum value of a difference in length of the plugged portions at the corners in the cell extending direction is 5 mm or more and 25 mm or less.   In the corner portion in the one cell of the gas inflow end face plugged cell, the length in the cell extending direction of the plugging portion of each corner portion is 2 mm or more starting from the exhaust gas inflow end face. The honeycomb structure according to claim 2, which is 35 mm or less.   Among the lengths of the gas inflow end face plugged cells in the one cell, the length of the plugging part extending from the corners in the cell extending direction, starting from the exhaust gas inflow end face. The honeycomb structure according to claim 2 or 3, wherein two or less of the lengths are the same.   The honeycomb structure according to any one of claims 1 to 4, wherein the number of the gas inflow end face plugged cells is 25 to 50% with respect to the total number of the cells.   The number of the through cells arranged so as to be adjacent to the two gas inflow end face plugged cells having the non-mirror symmetry is 50% or more with respect to the total number of the through cells, The honeycomb structure according to any one of claims 1 to 5.   The honeycomb structure according to any one of claims 1 to 6, wherein the partition wall has a thickness of 150 to 410 µm. The cell density of the honeycomb substrate is a 15 to 62 cells / cm ^2, the honeycomb structure according to any one of claims 1 to 7. A honeycomb formed body forming step of forming a honeycomb formed body having partition walls that partition and form a plurality of cells serving as fluid flow paths extending from one end face to the other end face by extruding a forming raw material;
A film disposing step of disposing a film covering a cell opening on one end face of the obtained honeycomb formed body or a honeycomb fired body obtained by firing the honeycomb formed body;
Forming a plugged portion in at least two cells to be plugged adjacent to cells that should not be plugged,
The plugging portion forming step includes
A perforation is formed in a part of the film covering each of the cells to be plugged, and the center of gravity of the perforation is shifted from the center of gravity of the cell opening of the cell to be plugged. A perforated part forming step;
By supplying the plugging material from the surface on which the film is disposed, the length in the cell extending direction of the plugging portion from the supply surface of the plugging material is within one cell. Including a plugging material supply step for forming different plugging portions,
A method for manufacturing a honeycomb structure.   In the perforated part forming step, the cell opening is a polygon having a plurality of corners, and the center of gravity of the perforated part is a straight line passing through the center of gravity of the cell opening and the corner of the cell opening. The method for manufacturing a honeycomb structured body according to claim 9, wherein the manufacturing method is shifted upward.   The method for manufacturing a honeycomb structured body according to claim 9, wherein, in the perforated part forming step, the center of gravity of the perforated part is shifted on a perpendicular drawn from the center of gravity of the cell opening to the partition wall.   In the perforated part forming step, the center of gravity of the perforated part for perforating the film covering each cell to be plugged is non-axisymmetric with respect to the film covering the cell not to be plugged. The method for manufacturing a honeycomb structured body according to any one of claims 9 to 11, wherein the perforated part is formed so that   The manufacturing method of the honeycomb structure according to any one of claims 9 to 12, wherein the plugging material has a viscosity of 100 to 400 Pa · s.