JP5188434B2 - Honeycomb filter and method for manufacturing honeycomb filter - Google Patents

Description

  The present invention relates to a honeycomb filter that collects particulate matter in exhaust gas and a method for manufacturing the honeycomb filter.

  In consideration of the impact on the environment, particulate matter contained in exhaust gas emitted from internal combustion engines such as automobile engines, construction machinery engines, stationary engines for industrial machinery, and other combustion equipment, is removed from the exhaust gas. There is a growing need for removal. In particular, regulations regarding the removal of particulate matter (particulate matter (also referred to as PM)) discharged from diesel engines tend to be strengthened worldwide. Under such circumstances, DPF (diesel particulate filter) for collecting and removing PM has been attracting attention.

  As one aspect of the DPF, a predetermined cell having a porous partition wall that partitions and forms a plurality of cells that serve as fluid flow paths, one end of which is open and the other end is plugged, The remaining cells whose end portions are plugged and the other end portions are opened alternately are arranged, and fluid (exhaust gas) flowing in from one end portion where predetermined cells open is separated by the partition walls. And a honeycomb filter in which PM in exhaust gas is collected and removed by flowing out from the other end where the remaining cells open. I can do it. A filter (wall flow type filter) having a structure in which exhaust gas permeates through porous partition walls, such as this honeycomb filter, can reduce the filtration flow rate (partition wall permeation flow rate) because the filtration area can be increased. The pressure loss is small, and the particulate matter collection efficiency is relatively good.

  However, the DPF to which the honeycomb filter as described above is applied has the following problems to be improved. That is, in recent years, low-pressure loss has been demanded while suppressing deformation of the partition walls and thermal stress generated at the endmost surface of the partition walls, so that the porosity of the partition walls is increased, the partition walls are thinner, and the sealing thickness is increased. Although it has been found that a certain effect can be obtained by reducing the thickness of the partition wall, when the porosity of the partition wall is reduced, the wall thickness of the partition wall is reduced, and the sealing thickness is reduced, the regeneration temperature is high. There is a tendency that the partition wall is greatly deformed, and particularly, the partition wall is largely deformed on the downstream end face. For this reason, problems such as cracks occurring at the partition walls at a lower temperature than before occur, and it was difficult to achieve low pressure loss while suppressing deformation of the partition walls and thermal stress generated at the outermost end surface of the partition walls. .

  In addition, in order to increase the porosity of the plugged portion, moisture may be increased in production, but in that case, the plugged portion may become insufficient (sink marks, voids), and the plugged portion The effect of leakage and soot leakage is a problem.

  Furthermore, in the case of a cell structure in which the upstream opening area is increased for the purpose of reducing pressure loss during ash deposition, the opening area of the downstream sealing part is large, and the porosity of the sealing part is increased. There is concern about the impact on soot leakage as DPF performance that causes a drop.

  There exist the following patent documents 1 and 2 with respect to such a subject.

  In Patent Document 1, as a filter (DPF) for collecting and removing particulate matter contained in exhaust gas exhausted from a diesel engine, a honeycomb structure sealed with a specified sealant and pores in the seal part The rate is 110 to 140% of the porosity of the honeycomb structure, and when the backwash air is ejected from the downstream portion, the fine particles accumulated in the partition walls are discharged through the plugged portion. A possible filter is disclosed.

  In Patent Document 2, a plurality of cells serving as flow paths partitioned by partition walls are provided, one end of a predetermined cell is sealed with a sealant, and the other sealed portion of the remaining cells is The honeycomb structure formed by sealing has a characteristic in which the Young's modulus of the sealing member is lower than the Young's modulus of the partition wall, and the porosity of the plugged portion is 105% or more of the porosity of the partition wall. A honeycomb structure that is less prone to cracking and excellent in durability is disclosed.

  However, Patent Documents 1 and 2 are characterized in that the porosity of the plugged portion is larger than the porosity of the partition wall, but there is a demand for lower pressure loss than in the past. By further increasing the porosity of the partition walls, reducing the wall thickness of the partition walls, and reducing the sealing thickness, the downstream partition walls are greatly deformed at a high regeneration temperature, and cracks are generated in the partition walls at a lower temperature than before.

  In addition, in order to increase the porosity of the plugged portion, the production water portion may be increased, but in that case, the plugged portion may be in an insufficient state (sink mark, void). The effect on sealing and soot leakage becomes a problem.

  In addition, in the case of a cell structure in which the opening area on the upstream side is increased for the purpose of reducing the pressure loss during ash deposition, the opening area on the downstream side is large, and the porosity of the sealing part is increased. There is concern about the impact on soot leakage as DPF performance.

JP 7-332064 A JP 2004-154692 A

  The present invention has been made in order to solve such problems, and at least the plugged portion formed on the downstream side includes a region A having a high porosity and a low porosity. A honeycomb filter that improves the rigidity of the entire downstream end face of the honeycomb structure, while suppressing deformation of the partition walls and thermal stress generated at the outermost end face of the partition walls. A method for manufacturing a honeycomb filter is provided. In particular, in the region A having a high porosity of the plugged portion, while suppressing the thermal stress generated on the outermost end surface of the partition wall, in the region B having a low porosity, the porosity of the plugged portion is reduced to reduce the compression strength. Improves regenerative performance while suppressing plugging and soot leakage throughout the plugged area, further improving the rigidity of the entire downstream end face of the honeycomb structure, and suppressing cracks during regeneration It is. In addition, the product yield is improved.

[1] A honeycomb structure including a large number of flow holes serving as exhaust gas flow paths partitioned by partition walls, and formed at an opening end formed on the downstream side of the large number of flow holes and on the upstream side. The opening end portion is formed with alternately plugged portions, and at least the plugged portion formed on the downstream side has a high porosity with respect to the porosity of the partition wall. It is configured as a plugged portion having a region A and a region B having a low porosity, and the plugged portion formed on the downstream side is formed as a two-layer structure including the region A and the region B. Further, the plugging portion formed on the upstream side is a plugged portion having a region A having a high porosity and a region B having a low porosity, or a region A having a high porosity, and a low porosity. Area B consisting of a rate, and a plug made of a two-layer structure The region A is formed on the end face side of the honeycomb filter, and the region B is formed apart from the end face side of the honeycomb filter. The honeycomb filter is formed as a region having a large pore in which the porosity of the region A is nonuniform and is formed in a stepwise manner .

[ 2 ] The porosity of the region A of the plugged portion is 104% or more with respect to the porosity of the partition wall, and the porosity of the region B is 98% or less with respect to the porosity of the partition wall. The honeycomb filter according to [1 ] .

[ 3 ] The honeycomb filter according to [1] or [ 2 ], wherein the porosity of the region B is greater than 75% with respect to the porosity of the partition wall.

[ 4 ] The honeycomb filter according to any one of [1] to [ 3 ], wherein the porosity of the region B is greater than 80% of the porosity of the partition wall.

[ 5 ] The honeycomb filter according to any one of [1] to [ 4 ], wherein the thickness of the region B is 20% or more with respect to the thickness of the entire plugged portion.

[ 6 ] The opening area of the upstream side of the flow hole is formed larger than the opening area of the outlet side, and includes a plugged portion including the region A and the region B only on the outlet side of [1] to [ 5 ]. The honeycomb filter according to any one of the above.

[ 7 ] The honeycomb structure is made of at least one ceramic selected from the group consisting of cordierite, SiC, mullite, aluminum, aluminum titanate, and SiN, according to any one of [1] to [ 6 ]. Honeycomb filter.

[ 8 ] A method for manufacturing the honeycomb filter according to any one of [1] to [ 7 ], wherein a plugged portion including a region A having a high porosity and a region B having a low porosity is formed. A method for manufacturing a honeycomb filter.

[ 9 ] After filling the end face of the honeycomb structure with a plugging member having a low porosity, the plugging member having a high porosity is further filled, and the plugging portion is dried once. [ 8 ] The method for manufacturing a honeycomb filter according to [ 8 ].

[ 10 ] Manufacture is performed by filling the end face of the honeycomb structure with a plugging member having a low porosity and then drying, and further filling the plugging member with a high porosity and performing a drying process. The manufacturing method of the honey-comb filter as described in 8 ].

  The honeycomb filter according to the present invention has the following effects when applied as a DPF.

  In the honeycomb filter according to the present invention, at least the plugged portion formed on the downstream side is configured as a plugged portion including a region A having a high porosity and a region B having a low porosity. The present invention provides excellent effects such as providing a honeycomb filter that improves the rigidity of the entire downstream end face of the honeycomb structure and a method for manufacturing the honeycomb filter while suppressing deformation of the partition walls and thermal stress generated at the end face of the partition wall. is there. In particular, in the region A having a high porosity of the plugged portion, while suppressing the thermal stress generated on the outermost end surface of the partition wall, in the region B having a low porosity, the porosity of the plugged portion is reduced to reduce the compression strength. Improves regenerative performance while suppressing plugging and soot leakage throughout the plugged area, further improving the rigidity of the entire downstream end face of the honeycomb structure, and suppressing cracks during regeneration It is. In addition, the product yield is improved.

FIG. 2 is a perspective view schematically showing one embodiment of a honeycomb filter according to the present invention. FIG. 2 is a plan view schematically showing one embodiment of a honeycomb filter according to the present invention. FIG. 2 is a diagram showing an embodiment of a honeycomb filter according to the present invention, and is a diagram schematically showing a cross section in the length direction of the honeycomb filter. It is the enlarged view to which the sealing part 6 shown by FIG. 3A was expanded. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which showed typically the cross section of the length direction of a honey-comb filter. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which showed typically the cross section of the length direction of a honey-comb filter. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is a figure which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure which expanded the plugged part of the honey-comb filter, and showed the cross section of the length direction typically. It is the perspective view which shows another embodiment of the honey-comb filter which concerns on this invention, Comprising: It is the figure shown typically.

  Hereinafter, the form for implementing the honeycomb filter of this invention is demonstrated concretely. However, the present invention broadly includes honeycomb filters having the invention-specific matters, and is not limited to the following embodiments.

[1] Honeycomb filter of the present invention:
1 to 3B, the honeycomb filter of the present invention includes a honeycomb structure 1 including a large number of flow holes 3 that serve as exhaust gas flow paths partitioned by partition walls 4. The open end portion 11 (11a) formed on the downstream side of the first and the open end portion 11 (11b) formed on the upstream side are formed with alternately plugged portions 6 and at least The plugging portion 6 formed on the downstream side has a region A (reference numeral 7 in FIG. 3A) having a high porosity and a region B (FIG. 3) having a low porosity with respect to the porosity of the partition wall 4. 9), the honeycomb filter 1 is formed as a plugged portion 6.

[1-1] Sealing part:
The plugged portion formed in the honeycomb according to the present embodiment, at least the plugged portion formed on the downstream side includes a region A having a high porosity and a low porosity with respect to the porosity of the partition wall. It comprises as the area | region B which consists of. Thus, when the plugged portion formed of the region A having a high porosity and the region B having a low porosity is formed, the plugged portion provided in the conventional honeycomb filter is as follows. Are better. That is, (1) By forming the region B having a low porosity, at least a part of the plugging portion of the entire end surface (downstream end surface portion) formed on the exhaust gas outflow side of the honeycomb structure is reduced. As a result, the rigidity of the entire downstream end surface portion of the honeycomb structure can be improved while suppressing deformation and cracking of the partition walls. Further, (2) the area A (sealed area A on the surface side) of the plugged portion formed on the end face side of the honeycomb filter has a high porosity, particularly, the porosity in the area A with respect to the wall porosity. Therefore, the region B formed away from the end face side of the exhaust gas filter has a low porosity, particularly, a smaller porosity than the partition wall porosity. Therefore, the deformation of the partition wall can be suppressed. (3) Furthermore, since the area A (sealed area A on the surface side) of the plugged portion formed on the end face side of the honeycomb filter has a high porosity, sink marks or voids in the plugged portion are likely to occur. Normally, such sink marks or voids in the plugged portion tend to weaken the strength of the entire plugged portion, and as a result, adverse effects such as plugging and soot leakage tend to occur. However, in this embodiment, since the region B having a low porosity is formed while being connected to the region A (while adjacent), the region B can improve the crimping strength of the entire sealed portion, Can prevent sealing and soot leakage. (4) Further, since the region A has a high porosity, it is easy to relieve high thermal stress, and it is easy to suppress cracks during regeneration. For example, the region A is formed from uneven high porosity such as sink marks and voids. But the effect is obtained.

[1-1-1] (Sealed portion) Region A:
The area A of the plugged portion in the present embodiment is desirably formed as having a higher porosity than the partition wall. This is because stress relaxation can be realized by increasing the porosity of the region A. That is, the stress to the partition wall can be relaxed in the region A, and the stress can be more easily relaxed. The area A of the plugged portion is formed by layering as described later, formed by changing each porosity stepwise, or formed as a space without being filled with a plugging member. Is also included. This is because the formation of the high porosity region produces the effects of the present application in combination with the region B described later.

  Here, when the region A is filled with a plugging member to form a plugging layer, the material of the plugging member filled in the region A can be the same as that of the partition wall. In this regard, when the sealing member is made of silicon carbide, cracks may occur on the end face of the honeycomb structure due to the high Young's modulus of the silicon carbide itself. However, by increasing the porosity of the region A, the Young's modulus can be lowered and used, and cracks can be prevented from occurring on the end face of the honeycomb structure.

  Moreover, it is preferable that the area | region A forms the plugging part as the below-mentioned area | region B and 2 layer structure. In addition to easy formation of the entire sealed portion, the thermal stress that can occur in the partition wall is easily absorbed and dispersed by the region A, so that deformation of the partition wall can be reliably suppressed, and the effects of the present application can be further exhibited. is there. Moreover, it becomes easy to cooperate with the below-mentioned area | region B, and by cooperating with the area | region A and the area | region B, it is possible to suppress plugging and soot leakage as the entire sealing portion, and to prevent cracks in the partition wall that may occur during the regeneration process. This is because it can be suppressed.

  The region A is preferably formed on the end face side of the honeycomb filter. By being formed on the end face side of the honeycomb filter, it becomes easy to surely relieve stress in the end face side region where stress is likely to concentrate, and in combination with the later-described region B, it prevents plugging and soot leakage. It is because it becomes easy to suppress. In addition, the case where the region A is formed on the end face side of the honeycomb filter as described above means that the region A is formed without being separated from at least the end face of the exhaust gas filter (open end face of the flow hole). B means continuous. In other words, when the end surface formed on the exhaust gas outflow side of the honeycomb filter is viewed as the upper end, the region A filled with the sealing member is continuously formed in the region above the region B, region B The region A is continuously formed while a gap is formed without being sufficiently filled in the region above the sealing member, and further, the region above the region B is completely filled with the sealing member. A region in which no region A is continuously formed is included. More specifically, (1) As shown in FIGS. 5A, 5C, and 5D, the boundary regions that are the contours of the regions A and B are continuous, and the sealing members are stacked in layers. (2) As shown in FIGS. 5E and 5F, the boundary regions that are the contours of the regions A and B are continuous, and the region Z is not sufficiently filled with the sealing material, and the gap Z is formed. Formed, the sealing material of the region A and the region B is not continuous, (3) as shown in FIG. 5B, the boundary region that is the contour of each of the region A and the region B is continuous, and An example in which the area A is not filled with any plugging material and is formed as a space area can be given as an example.

  The length (depth) of the region A in the major axis direction of the honeycomb structure is preferably 1 to 12 mm. If it is shorter than 1 mm, stress relaxation or the like cannot be realized sufficiently, and the pressure loss as a filter may increase. If it is longer than 12 mm, the area B to be described later is formed. Thus, the length of the region B plugged portion cannot be sufficiently secured, the rigidity of the entire downstream end surface portion of the honeycomb structure is lowered, and the length of the entire plugged portion is secured to secure the length of the region B plugged portion. Becomes longer, leading to a reduction in the filtration area of the filter, and the pressure loss is significantly increased. Moreover, it is preferable that the area | region in which the area | region A is formed is formed in the range of 1-12 mm toward the major axis direction from the same surface as the end surface of a honeycomb filter. By forming the region A in such a region, it is possible to reliably relieve stress that tends to concentrate on the end face side, and the effects of the present application can be further achieved in combination with the region B described later. On the other hand, when the region A is formed in a region exceeding the range of 12 mm, it is difficult to sufficiently relieve stress that tends to concentrate on the end face side, and it is also likely to reduce the filtration area of the filter and reduce the purification efficiency. Furthermore, it is not preferable because it is difficult to improve the rigidity of the entire downstream end surface portion of the honeycomb structure.

  Moreover, it is preferable that each porosity of the area | region A changes in steps. By being configured in this manner, it is easy to form a region having a suitable porosity according to the stress that tends to concentrate on the end face side, and stress relaxation can be performed in the region A step by step. That is, also in the region A, the thermal stress load is not uniform between the end surface side and the region away from the end surface side, and the thermal stress on the end surface side tends to be larger. However, because the honeycomb shape, the shape of the flow holes, the partition wall thickness, etc., the stress may increase even from the partition wall around the region A toward the flow hole in the axial direction (center portion). For example, the porosity is increased in the end face side area in the area A, and the porosity is reduced in the area away from the end face side in the area A compared to the end face side area in the area A. The porosity from the end face side region in A to the region B is changed stepwise, for example, the porosity is changed stepwise from the partition wall around the region A toward the axial direction of the flow hole, While relieving stress reliably, coupled with region B, which has a lower porosity than the partition wall, improves the rigidity of the entire downstream end face, thereby reducing cracks in the partition wall while maximizing thermal stress relaxation. To prevent It can be obtained more the effect of the present application. As an example of such a region A in which the porosity is changed stepwise, (1) the region A shown in FIGS. 5A, 5C, and 5D (boundary regions that are the respective contours of the region A and the region B) In which the sealing members are stacked in a layered manner), (2) the region A shown in FIGS. 5E and 5F (the boundary regions that are the contours of the regions A and B are continuous, and the region And A is not sufficiently filled with the plugging material and a gap is formed, and the plugging materials in the region A and the region B are not continuous).

  Moreover, it is one of the preferable forms that the porosity of the region A is not uniform and is formed as a region having large pores. An example of such a region A having a non-uniform porosity and a region having large pores is, for example, (5) in the axial direction (center axis direction) as shown in FIG. 5C. As an example, a region A formed as a region having hollow large pores X can be cited as an example.

  Moreover, it is preferable that the porosity of the area | region A of a sealing part is 104% or more with respect to the porosity of a partition. By being configured in this manner, the region A can easily absorb and disperse the stress on the partition walls, and the stress on the partition walls can be relaxed, so that cracks can be prevented in advance. On the other hand, when the porosity of the region A of the plugged portion is smaller than 104% with respect to the porosity of the partition wall, it becomes difficult to relieve stress and cracks are easily generated in the partition wall. Is preferably formed to 104% or more.

[1-1-2] (Sealed portion) Region B:
The region B of the plugged portion formed in the honeycomb filter of the present embodiment is desirably formed as a region having a lower porosity than the partition wall. By forming the region B having a low porosity, a low porosity can be realized at least in a part of the sealing portion of the entire end surface (downstream end surface portion) formed on the exhaust gas outflow side of the honeycomb structure. As a result, the rigidity of the entire downstream end surface portion of the honeycomb structure can be improved while suppressing deformation of the partition walls and cracks of the partition walls. Furthermore, since the area A of the plugged portion is formed with a high porosity, it is continuous with the region A so as not to cause a sink or void in the plugged portion and cause problems such as plugging through and soot leakage. However, the region B having a low porosity is formed while (adjacently) to improve the pressure-bonding strength of the entire plugged portion, and to prevent plugging and soot leakage.

  Here, the region B of the sealing portion in the present embodiment includes those formed by layering as will be described later, and those formed by changing each porosity stepwise, but as in the region A What was made into the space in the state which is not filled with the sealing member is not included. If the region B is formed as a space not filled with a sealing member such as the region A, the rigidity of the entire end surface portion as well as the region B cannot be improved, and further, there is a sink or gap in the sealing portion. This is because it is liable to cause harmful effects such as sealing and soot leakage.

  Here, the material of the sealing member in the region B can be the same as the material of the partition wall. In this regard, when the sealing member is made of silicon carbide, cracks may occur on the end face of the honeycomb structure due to the high Young's modulus of the silicon carbide itself. However, by lowering the porosity of the region B, the Young's modulus can be increased and used, the rigidity of the entire end face part can be improved as the whole plugged part, and further, the sink or void of the plugged part is prevented, It is possible to prevent harmful effects such as sealing and soot leakage.

  Moreover, it is preferable that the area | region B forms the plugging part as the above-mentioned area | region A and a 2 layer structure. In addition to facilitating the formation of the entire plugged portion, it becomes easier to improve the rigidity of the entire downstream end face of the honeycomb structure. This is because the effect of the present application can be further achieved because the cracks in the partition walls that can be reliably suppressed and can occur during the regeneration process can be suppressed.

  Moreover, it is preferable that the region B is formed away from the end face side of the exhaust gas filter. By being configured in this way, the region A with high air efficiency is formed on the end face side of the honeycomb filter, so that the stress can be relieved reliably in the end face side region where the stress tends to concentrate, and the honeycomb filter This is because, in the region B where the concentration of stress is reduced as compared with the end face side, the rigidity of the entire end face portion is reliably improved, and further, the entire plugged portion can be easily prevented from being sealed and soot leakage. When the region B is formed so as to be separated from the end face side of the honeycomb filter as described above, the region B is formed at least at a distance from the end face of the exhaust gas filter (open end face of the flow hole). It means that the area A is continuous. In other words, when the end surface formed on the exhaust gas outflow side of the honeycomb filter is viewed as the upper end, the region B filled with the sealing member is continuously formed in the region below the region A. To do. More specifically, as described above, (1) as shown in FIGS. 5A, 5C, and 5D, the boundary regions that form the respective contours of the regions A and B are continuous, and the sealing members are layered. As shown in FIGS. 5E and 5F, the boundary areas that are the outlines of the areas A and B are continuous, and the area A is not sufficiently filled with the sealing material. A gap Z is formed in the region A and the plugging material of the region B is not continuous. (3) As shown in FIG. 5B, the boundary regions that are the respective contours of the region A and the region B are An example is one that is continuous and is formed as a space region without being completely filled with the plugging material in the region A.

  The length (depth) of the region B in the major axis direction of the honeycomb structure is preferably 4 to 16 mm. If the length is shorter than 4 mm, the rigidity of the entire end face cannot be improved sufficiently, and cracks may occur due to large deformation of the partition wall. If the length is longer than 16 mm, the rigidity of the sealing member is remarkably increased and formed around the region B. The stress of the partition walls cannot be sufficiently absorbed and dispersed, and cracks are likely to occur in the partition walls. Further, when forming the region A described later, the length of the plugged portion of the region A cannot be sufficiently secured with respect to the entire length of the plugged portion, it is difficult to relax the stress generated on the end face of the partition wall, and cracks are likely to occur. Become. This is not preferable because it may reduce the filtration area of the filter and may reduce the purification efficiency. Moreover, it is preferable that the area | region in which the area | region B is formed is formed in the range of 4-16 mm toward the major axis direction from the same surface as the end surface of a honeycomb filter. By forming the region B in such a region, it becomes easy to improve the rigidity of the entire downstream end surface portion of the honeycomb structure, so that the entire plugged portion can be plugged and soot leaked in cooperation with the aforementioned region A. This is because the effects of the present application can be further enhanced since the cracks in the partition walls that can occur during the regeneration process can be suppressed. On the other hand, if the region B is formed in a region smaller than the 4 mm range, the region A cannot be formed sufficiently and it is difficult to relax the stress. In addition, if the region B is formed in a region exceeding the range of 16 mm, the formation region of the region A may become too large, and the filtration area of the filter may be reduced and the pressure loss may be significantly increased. Absent.

  Moreover, it is preferable that each porosity of the area | region B changes in steps. Such a configuration is preferable because stress relaxation can be performed in a stepwise manner with respect to stress that tends to concentrate on the end face side even in the region B. That is, even in the region B, a stress is applied even if it is not as large as the region A, but the stress load is not uniform between the end surface side of the region B and the region away from the end surface side. That is, the thermal stress on the honeycomb end face side in the region B tends to become larger. However, because the honeycomb shape, the shape of the flow holes, the thickness of the partition walls, and the like, the stress may increase even from the partition wall around the region B in the axial direction (center portion) of the flow holes. For example, in the end face side area in the area B, the porosity is relatively higher, and the area further away from the end face side area of the area B (in the area B) is compared with the end face side area in the area B described above. Then, the porosity from the end face side region to the region B in the region B is changed in a stepwise manner, for example, from the partition wall around the region B toward the axial direction of the flow hole. The effect of the present application can be further exhibited by performing stress relaxation in combination with the region A while the porosity is changed stepwise and the rigidity of the entire downstream end face portion is reliably improved.

  Moreover, it is preferable that the porosity of the area | region B is 98% or less with respect to the porosity of the said partition. Such a configuration is preferable because the soot leakage can be more reliably prevented while further improving the rigidity of the entire downstream end surface portion. On the other hand, when the porosity of the region B of the plugged portion is greater than 98% with respect to the porosity of the partition wall, it becomes difficult to improve the rigidity of the entire downstream end surface part, or the rigidity cannot be maintained, and soot leaks easily. Or cracks are likely to occur in the partition wall, which is not preferable.

  Furthermore, the porosity of the region B is preferably greater than 75% with respect to the porosity of the partition wall. By being configured in this manner, the rigidity of the entire downstream end surface portion can be further improved, soot leakage can be more reliably prevented, and cracks are less likely to occur in the partition wall, which is preferable. On the other hand, when the porosity of the region B of the plugged portion is less than 75% with respect to the porosity of the partition wall, the stress of the partition wall formed around the region B cannot be sufficiently absorbed and dispersed. Since it becomes difficult to move, it is not preferable because cracks are likely to occur.

  More preferably, the porosity of region B is greater than 80% of the porosity of the partition walls. By being comprised in this way, while further improving the rigidity of the whole downstream end surface part, a soot leak can be prevented more reliably, and also a crack can be prevented more reliably in a partition.

  Further, the thickness of the region B is preferably 20% or more with respect to the thickness of the entire plugged portion, and the thickness of the region B is 20% with respect to the thickness of the entire plugged portion. % Or more and 80% or less is preferable. When the thickness of the region B is 20% or more with respect to the entire thickness of the plugged portion, it is possible to reliably prevent soot leakage while improving the rigidity of the entire downstream end surface portion, and to further crack the partition wall. Therefore, the effects of the present application can be generally achieved. On the other hand, if the thickness of the region B is smaller than 20% of the total thickness of the plugged portion, the rigidity of the entire downstream end surface portion is likely to be fragile, and soot leakage and cracks to the partition walls are likely to occur. It is not preferable. Further, if the thickness of the region B is larger than 80% with respect to the entire thickness of the plugged portion, it is difficult to relieve stress, which is not preferable.

[1-1-3] Specific example of plugging portion:
In the honeycomb filter of the present embodiment, the region A and the region B described so far combine to produce the effect of the present application synergistically, and the region A and the region B have the following configurations. And it is easy to show the effect of this application. Below, the example of the plugging part which consists of the area | region A and the area | region B is demonstrated concretely. However, for the individual descriptions of the region A and the region B, refer to the description of the [1-1-1] region A and the [1-1-2] region B described above.

  It is preferable that the plugged portion formed on the downstream side is formed as a two-layer structure including a region A and a region B. When it is formed as a two-layer structure, it is easy to form the entire plugged portion, and it is easy to improve the rigidity of the entire downstream end surface portion of the honeycomb structure. Furthermore, the region A and the region B can easily cooperate with each other, the sealing portion as a whole can be prevented from being sealed and soot leakage can be reliably suppressed, and the crack of the partition wall that can occur during the regeneration process can be suppressed. Specifically, as a plugged portion having a two-layer structure, a plugged portion formed of a region A and a region B as shown in FIGS. 5A and 5C to 5E can be given as an example.

  For example, the region A is formed with a higher porosity than the partition wall, and the region B is lower in porosity than the partition wall and has a two-layer structure as a plugged portion (1) as shown in FIG. 3B. An example is a plugged portion in which the porosity of the regions A and B is uniformly formed in each of the regions A and B. Further, (2) a plugged portion formed as a two-layer structure including a region A in which small voids as shown in FIG. 5A are formed sparsely (sparsely), and (3) shown in FIGS. 5D and 5E. As shown in FIG. 5E, the plugged portion including the region A in which the concave portion is formed in the axial direction (central axial direction), and the axial direction (central axial direction). And a sealing portion including a region A in which a sealing member is not filled in a boundary region with the region B and a gap is formed in the boundary region with the region B, as shown in FIG. 5C. In addition, in the center in the axial direction (center axis direction), a plugged portion including a region A having a hollow large pore, or (6) the region A of any one of the above (1) to (5) Examples include a plugged portion including a region A formed by a combination of However, the present invention is not limited to the plugged portion formed of the region A or the region B, and the honeycomb filter plugged in the present embodiment can be used as long as the configuration of the present application is employed and the effect of the present application is achieved. Included in the department.

  Furthermore, the plugged portion formed on the upstream side is a plugged portion having a region A having a high porosity and a region B having a low porosity, or a region A having a high porosity, and a low porosity. It is also one of the preferable forms that it is configured as a plugged portion having a two-layer structure of a region B made of In the honeycomb filter, stress tends to concentrate, particularly on the partition wall on the end face side formed on the downstream side. Therefore, as described above, it is desirable to reduce the stress by forming the region A of the sealing portion formed on the downstream side as described above. However, the stress concentration also occurs in the partition wall on the end surface side formed on the upstream side. Prone to occur. Therefore, the plugged portion formed on the upstream side is a plugged portion including a region A having a high porosity and a region B having a low porosity, or a region A having a high porosity, and a low porosity. The region B is formed as a plugged portion having a two-layer structure, so that the honeycomb filter as a whole can prevent stress leakage and cracks while at the same time reducing stress, and can generally exhibit the effects of the present application. one of.

  In addition, it is preferable that the region A is formed on the end face side of the honeycomb filter and the region B is formed apart from the end face side of the exhaust gas filter. With this configuration, since the regions A and B are formed in appropriate regions, the entire honeycomb filter can relieve stress while the regions A and B cooperate with each other. It is preferable because leakage and cracks can be prevented in advance. Specifically, as shown in FIGS. 3 and 5A to 5F, a region A is formed on the end surface side of the honeycomb filter, and a plugged portion formed by separating the region B from the end surface side of the exhaust gas filter is provided. As an example.

  Moreover, it is preferable that each porosity of the area | region A and the area | region B changes in steps. By being configured in this way, it becomes easier to form a region having a suitable porosity according to the stress that tends to concentrate on the end face side, and stress relaxation can be performed stepwise from region A to region B. To preferred. That is, also in the region A, the thermal stress load is not uniform between the end surface side and the region away from the end surface side, and the thermal stress on the end surface side tends to be larger. In the region B, stress is applied even if it is not as large as the region A. However, the stress load is not uniform between the end surface side of the region B and the region away from the end surface side. The thermal stress on the honeycomb end face side in the region B tends to become larger. However, due to the shape of the honeycomb, the shape of the flow hole, or the thickness of the partition wall, the stress is larger even from the partition wall around the region A (or region B) toward the axial direction (center portion) of the flow hole. Sometimes. Therefore, for example, in the end surface side region in the region A, the porosity is further increased, and in the region away from the end surface side in the region A, the porosity is decreased as compared with the end surface side region in the region A. The porosity of the region A from the end surface side region to the region B is changed stepwise, and the region further away from the end surface side region of the region B (region B) is compared with the end surface side region in the region B described above. It is also preferable that the porosity from the end face side region to the region B in the region B is changed stepwise by lowering the porosity. For example, it is also preferable that the porosity is changed stepwise from the partition wall around the region A (or region B) toward the axial direction of the flow hole. By forming the porosity from region A to region B stepwise in this way, the downstream end face combined with region B that has a lower porosity than the partition wall while reliably relaxing stress. The rigidity of the entire part can be improved, and cracks in the partition walls can be prevented while maximizing the relaxation of thermal stress.

  Moreover, it is preferable that the porosity of the region A of the plugged portion is 104% or more of the porosity of the partition wall, and the porosity of the region B is 98% or less of the porosity of the partition wall. By being configured in this manner, the area A can easily absorb and disperse the stress to the partition wall, and the stress to the partition wall can be relieved, so that cracks can be prevented in advance, and the region B can improve the rigidity of the entire downstream end face part. While further improving, soot leakage can be prevented more reliably, and the region A and the region B are combined, so that the effects of the present application can be easily achieved, which is preferable. On the other hand, when the porosity of the region A of the plugged portion is smaller than 104% with respect to the porosity of the partition wall, the stress cannot be relieved, and the partition wall is likely to crack, and the porosity of the region B of the plugged portion is further increased. If the porosity is higher than 98% with respect to the porosity of the partition wall, it becomes difficult to improve the rigidity of the entire downstream end surface portion, or the rigidity cannot be maintained, so that soot leakage is likely to occur, or cracks are likely to occur in the partition wall. It is not preferable.

  Further, it is preferable that the upstream side opening area of the flow hole is formed larger than the outlet side opening area, and the honeycomb filter is provided with a plugged portion including the region A and the region B only on the outlet side. By being configured in this way, it is possible to further relieve stress at the outlet side end face while improving the purification treatment efficiency, and at the same time to simultaneously suppress cracks during regeneration and improve regeneration performance. it can.

[1-2] Other configurations of the honeycomb filter:
As shown in FIGS. 1 to 3, the base material of the honeycomb filter according to the present embodiment includes a plurality of cells that are defined by partition walls 4 made of porous ceramic having a large number of pores and serve as exhaust gas flow paths. It comprises a honeycomb structure provided. In this honeycomb structure, an opening end 7b formed on the downstream side of a large number of flow holes and an opening end 7a formed on the upstream side are formed, and the opening ends 7b and 7a are alternately arranged. A plugged portion is formed by sealing. Furthermore, at least the plugged portion formed on the downstream side is configured as a plugged portion including a region A having a high porosity and a region B having a low porosity with respect to the porosity of the partition wall. . However, the overall shape of the honeycomb structure is not particularly limited, and examples thereof include a quadrangular prism shape and a triangular prism shape in addition to the cylindrical shape shown in FIGS.

  Moreover, as the opening shape of the flow hole provided in the honeycomb structure (also referred to as a cell shape, the shape of the cell in a cross section perpendicular to the cell forming direction), for example, a square cell, a hexagonal shape as shown in FIG. Examples of the shape include a cell and a triangular cell. However, it is not limited to such a shape, and can widely include known cell shapes. More preferable cell shapes include a circular cell or a polygonal cell having a quadrangle or more. The reason why such a circular cell or a polygonal cell having a quadrangle or more is more preferable is that cracks during regeneration can be easily suppressed and inflow and outflow of exhaust gas can be easily controlled while relaxing high thermal stress. In particular, in consideration of cell density, opening ratio, etc., hexagonal cells are preferable, more preferably rectangular cells (upstream opening shape) in which the upstream opening area is easier to form than the outlet opening area, and hexagonal cells. A plurality of cells combined with (downstream opening shape) are provided. In this way, by combining a plurality of cells composed of square cells-hexagonal cells to form an opening on the honeycomb end surface, and further forming a plugged portion as will be described later, the end surface on the outlet side is improved while improving purification efficiency. This is preferable because stress relaxation can be further improved, and cracks during reproduction can be suppressed and reproduction performance can be improved at the same time.

The cell density of the substrate having the honeycomb structure is not particularly limited, but when used as a honeycomb filter as in the present embodiment, it is in the range of 6 to 1500 cells / in ² (0.9 to 233 cells / cm ² ). It is preferable that Moreover, it is preferable that the thickness of a partition is the range of 20-2000 micrometers.

  Moreover, it is preferable that the porosity of the partition provided in the honeycomb structure is 35 to 75%. When the porosity of the partition walls is lower than 35%, the permeability of the partition walls themselves is remarkably lowered. Therefore, the pressure loss increase with respect to the soot deposition amount shows a linear tendency, but the pressure loss without soot deposition increases greatly. If the porosity is higher than 75%, the material strength is lowered, and cracks may occur during canning.

  Further, in this specification, “average pore diameter” and “porosity” mean the average pore diameter and porosity measured by the mercury intrusion method.

  Moreover, it is preferable that the pore diameter of the partition provided in the honeycomb structure base material is 5 to 40 μm. If the pore diameter is smaller than 5 μm, the permeability is very low, and the pressure loss without soot deposition becomes very high. If it is larger than 40 μm, PM cannot be sufficiently collected when the exhaust gas permeates through the partition walls, and easily passes through, so that the collection efficiency is not sufficient. On the other hand, if the pore diameter of the partition wall is smaller than 5 μm, the intrusion pressure when the exhaust gas permeates the partition wall becomes excessive and cracks are likely to occur, which is not preferable.

  Furthermore, it is preferable that the thickness of the partition provided in the honeycomb structure base material is 200 to 600 μm. If it is smaller than 200 μm, the heat capacity becomes small, and the accumulated soot may burn abnormally during regeneration, so that the internal temperature of the DPF rises rapidly and may cause cracks. If it is larger than 600 μm, the hydraulic diameter becomes too small and the pressure loss becomes high.

When used as a honeycomb filter as in the present embodiment, it is desirable that the honeycomb structure has a structure in which one open end and the other open end of a plurality of cells are alternately plugged. For example, as shown in FIG. 3A, a honeycomb structure having a plurality of cells 3 serving as gas flow paths, partitioned by partition walls 4 made of porous ceramic having a large number of pores, A structure in which one opening end portion 11a and the other opening end portion 11b are alternately plugged by the plugging portions 8 is preferable. In such a honeycomb structure, when the exhaust gas inflow cells 3 that open toward the exhaust gas inlet side end face 11a to flow into the exhaust gas G _1, the particulates in the exhaust gas G ₁ when the exhaust gas G ₁ is passed through the partition wall 4 trapped in the partition walls 4, and purified gas G ₂ from which particulate matter has been removed, will flow out from purified gas outflow cells 3 that open toward the exhaust gas outlet side end face 11b.

  The material of the substrate of the honeycomb structure is not particularly limited, but ceramic can be suitably used, and from the viewpoint of strength, heat resistance, corrosion resistance, etc., any of cordierite, silicon carbide, alumina, mullite, or silicon nitride It is preferable that

  Further, the base material of the honeycomb structure as described above includes, for example, aggregate particles made of ceramic, water, organic binder (hydroxypropoxymethylcellulose, methylcellulose, etc.) and pore former (graphite, starch, synthetic resin as required) Etc.), a surfactant (ethylene glycol, fatty acid soap, etc.), etc. are mixed and kneaded to form a clay, the clay is molded into a desired shape, and dried to obtain a molded body. Can be obtained by firing.

In addition, an oxidation catalyst, another catalyst, and a purification material may be further supported on the partition walls of the honeycomb structure base material. For example, NO _x storage catalyst, three-way catalyst, cerium (Ce) and / or zirconium (Zr) made of alkali metals (Li, Na, K, Cs, etc.) and alkaline earth metals (Ca, Ba, Sr, etc.) A co-catalyst typified by an oxide, an HC (Hydro Carbon) adsorbent, or the like may be supported.

  As a method for manufacturing the honeycomb structure, for example, the following method is given as an example. However, the present invention is not limited to such a method for manufacturing a honeycomb structure, and a known method for manufacturing a honeycomb structure can also be used.

  The honeycomb structure is, for example, a honeycomb segment bonded body 63 including a plurality of honeycomb segments 62 as shown in FIG. 6, the segments are bonded to each other with a bonding material 64, and the outer peripheral surface is cut into a desired shape. In the case of being molded, the following procedure is recommended.

  First, honeycomb segments are produced. As the honeycomb segment raw material, for example, SiC powder and metal Si powder are mixed at a mass ratio of 80:20, and methyl cellulose and hydroxypropoxyl methyl cellulose, a surfactant and water are added and kneaded to form a plastic clay. Got. Then, the kneaded material is extruded using a predetermined mold to form a honeycomb segment formed body having a desired shape. Next, the obtained honeycomb segment formed body is dried by a microwave dryer, and further completely dried by a hot air dryer, and then plugged and fired (calcined).

  This calcining is performed for degreasing and includes, for example, one performed at 550 ° C. for about 3 hours in an oxidizing atmosphere, but is not limited to this, and the organic matter in the honeycomb formed body It is preferably carried out according to (organic binder, dispersant, pore former, etc.). Generally, the combustion temperature of the organic binder is about 100 to 300 ° C., and the combustion temperature of the pore former is about 200 to 800 ° C. Therefore, the calcining temperature may be about 200 to 1000 ° C. Although there is no restriction | limiting in particular as a calcination time, Usually, it is about 3 to 100 hours.

  Further, firing (main firing) is performed. The “main firing” means an operation for sintering and densifying the forming raw material in the calcined body to ensure a predetermined strength. Since the firing conditions (temperature and time) vary depending on the type of molding raw material, appropriate conditions may be selected according to the type. For example, the firing temperature when firing in an Ar inert atmosphere is generally about 1400 ° C. to 1500 ° C., but is not limited thereto.

  After obtaining a plurality of honeycomb segments (sintered bodies) having desired dimensions through the steps as described above, aluminosilicate fiber, colloidal silica, polyvinyl alcohol, and silicon carbide are kneaded on the peripheral surface of the honeycomb segments. The joining slurry is applied, assembled and pressure-bonded to each other, and then dried by heating to obtain a bonded honeycomb segment assembly having an overall shape of a quadrangular prism. Then, after the honeycomb segment bonded body is ground into a cylindrical shape, the peripheral surface is covered with an outer peripheral coat layer made of the same material as the honeycomb segment molded body, and cured by drying, thereby providing a column having a segment structure. A honeycomb structure having a shape can be obtained.

  As a method for forming the plugging portion, when the region A is filled with a plugging member, the plugging slurry in the region A is prepared and stored so that the porosity of the partition wall is high. Store in a container. Similarly, the plugging slurry in the region B is prepared so as to have a low porosity with respect to the porosity of the partition wall, and stored in a storage container different from the region A described above. Next, the end of the honeycomb structure on which the mask is applied is dipped in a storage container, and the opening of the cell not subjected to the mask is filled with the plugging slurry in the region B. Further, the plugging slurry filled in the region B is not heat-treated, and the plugging slurry in the region A is filled on the region B to form a plugging portion including the region B and the region A. . For the other end, a mask is applied to the cells plugged at one end, and the cells that are not plugged at the one end are filled with the plugging slurry in region B. The plugging portion may be formed, or, similarly to the above, after filling the plugging slurry in the region B, the region without the heat treatment of the plugging slurry filled in the region B may be used. The plugging slurry of A may be filled to form a plugged portion composed of region B and region A, thereby forming a plugged portion. As a result, the cells not plugged at the one end are plugged at the other end, and the cells are alternately closed in a checkered pattern at the other end. The plugging may be performed after the honeycomb formed body is fired to form the honeycomb fired body.

  Further, when the region A in the plugged portion is not formed, after preparing only the plugging slurry in the region B so as to have a low porosity with respect to the porosity of the partition wall, B may be filled with a plugging slurry to form a plugged portion. In such a case, since the region A is not formed, the plugged portion has a so-called hollow structure at least at the downstream end portion of the honeycomb structure. Similarly, in the upstream end portion of the honeycomb structure, the plugging slurry may be filled into the region B to form a plugged portion, and the plugged portion may be a hollow structure.

  Further, as a method for forming the plugging portion, as described above, after filling the region B with the plugging slurry, the filled plugging slurry is heat-treated, and the heat treatment is performed on the region B after the heat treatment. Further, the plugging slurry in the region A may be filled and heat-treated to form a plugging portion.

  In addition, as the plugging member in the region A and the plugging member in the region B, the raw materials of the plugging member are mixed into a slurry by mixing a ceramic raw material, a pore former, a surfactant, water, and the like, and then It can be obtained by kneading using a mixer or the like. As the kind of the ceramic raw material used for the raw material of the sealing member, a material that becomes a desired material of the sealing member may be used. For example, in the case of silicon carbide, a mixture of SiC powder and metal Si powder can be used. Preferably, it is the same as the ceramic raw material used when the ceramic molded body having the honeycomb structure is manufactured. In addition, silicon carbide can be used as a raw material for the sealing member. Further, the type of pore former used as a raw material for the sealing member is not particularly limited, but graphite, wheat flour, starch, phenol resin, polymethyl methacrylate, polyethylene, polyethylene terephthalate, foamed resin, shirasu balloon And fly ash balloons. Preferred are foamed resins and fly ash balloons that generate less heat during degreasing. The porosity and Young's modulus of the sealing member can be controlled by changing the kind and amount of the pore former. The addition amount of the pore former is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the ceramic raw material used as the raw material for the sealing member. Moreover, the kind of surfactant used for the raw material of the sealing member is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like.

  As the raw material for the sealing member, methyl cellulose, hydroxypropoxyl methyl cellulose, polyethylene oxide, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, etc. are used in addition to the ceramic raw material, pore former, surfactant and water. be able to.

  Further, for example, when cordierite is used as the material for the partition wall matrix, a dispersion medium such as water and a pore former are added to the cordierite forming raw material, and an organic binder and a dispersant are further added and kneaded. To form clay-like clay. The means for preparing the kneaded material by kneading the cordierite forming material (molding material) is not particularly limited, and examples thereof include a method using a kneader, a vacuum kneader or the like. When the cordierite raw material is fired, it is preferably fired at 1410 to 1440 ° C., and preferably fired for about 3 to 10 hours.

  In addition, as a shaping | molding method, the method etc. which extrude the clay prepared as mentioned above using the nozzle | cap | die which has a desired cell shape, partition wall thickness, and cell density can be used suitably.

[1-3] Manufacturing method of honeycomb filter according to the present invention:
Next, a method for manufacturing a honeycomb filter according to the present invention will be described. Examples of the method for manufacturing a honeycomb filter according to the present invention include the following method. However, the present invention is not limited to such a method for manufacturing a honeycomb structure, and can be manufactured by appropriately using a known method for manufacturing a honeycomb structure as long as the configuration of the present application is employed and the effects of the present application are achieved. .

  In the method for manufacturing a honeycomb filter described so far, the end face of the honeycomb structure is filled with a plugging member having a low porosity, and further filled with a plugging member having a high porosity, It is preferable to manufacture the plugged part by performing the drying process once. According to the manufacturing method of the present invention, after filling the region B with the sealing member, without further heat treatment, the region A is further filled with the sealing member, and then the heat treatment is performed to form the plugged portion. Similar to the so-called one-layer plugged portion in the prior art, the heat treatment of the plugged portion is only required once, energy efficiency can be improved, and an increase in cost burden can be suppressed. In particular, since the region A is filled without heat treatment, sink marks or the like can be generated in the region A, and a desired region A can be formed.

  Further, in the method for manufacturing a honeycomb filter described so far, the end face of the honeycomb structure is filled with a sealing member having a low porosity, followed by drying treatment, and further the sealing member having a high porosity. It is also one of the preferable forms to manufacture by filling and heat-processing. By manufacturing the honeycomb filter in this way, it becomes easy to provide stepped porosity in the region A and / or the region B, or a plugged portion having a uniform porosity in each of the regions A and B is provided. Since it can form, it is preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[1-1] Porosity of partition walls:
Take an image of the cross section of the honeycomb segment through SEM (Scanning Electron Microscope) and use the image analysis software (Media Cybernetics, “Image Pro Plus”) to measure the area of the partition wall and pores. The porosity was calculated. Specifically, the average space / solid area of 20 square fields (one side of the square is 1/1000 of the thickness of the partition wall) at a position sufficiently separated from the surface of the partition wall (center portion in the thickness direction of the partition wall). The ratio was measured and used as the porosity of the partition wall.

[1-2-1] Thickness of the region A and the region B in the plugged portion:
Using an image analysis device (trade name “NEXIV, VMR-1515” manufactured by Nikon Corporation), the cross-section of the honeycomb segment after forming the plugged portion is measured, and the thicknesses of the regions A and B in the plugged portion are measured. Calculated and determined.

[1-2-2] Thickness ratio of region A and region B in the plugged portion:
After obtaining the thicknesses of the region A and the region B in the plugged portion as described above, the thickness of the region A and the region B in the plugged portion is defined by setting the total thickness of the region A and the region B to 100. The ratios (1) and (2) were determined as follows.
(1) Thickness ratio (%) of region A in the sealing portion = (thickness of region A / (thickness of region A + thickness of region B) × 100
(2) Thickness ratio (%) of region B in the plugged portion = (thickness of region B / (thickness of region A + thickness of region B) × 100

[1-3-1] Porosity of region A and region B in the plugged portion:
Take an image of the honeycomb segment cross section through SEM (Scanning Electron Microscope) and use the image analysis software (Media Cybernetics, “Image Pro Plus”) to create a bipolar image. And the area of the region B part and the hole part were respectively measured, and the porosity of the region A part and the region B part was calculated. Specifically, in a position sufficiently distant from the surface of the plugged portion region A or region B (the central portion in the partition wall thickness direction), 20 square fields (one side of the square is 1/1000 of the partition wall thickness) The average space / solid area ratio was measured and used as the porosity of the region A and the region B in the plugged portion. Furthermore, when the area A and the area B were not filled with the sealing member, the porosity of each area was set to 100%.

[1-3-2] Porosity of region A and region B in the plugged portion:
After determining the porosity of the region A and the region B in the sealed portion as described above, the porosity ratios (3) and (4) of the region A and the region B in the sealed portion were determined as follows.
(3) Porosity ratio (%) of region A at the plugged portion = (porosity of region A / (partition wall porosity of each molded article)) × 100
(4) Porosity ratio (%) of region B in the plugged portion = (porosity of region B / (partition wall porosity of each molded body)) × 100

[2-1] Crack resistance:
A regeneration experiment was conducted in which soot was deposited by the engine, and the gas temperature was increased by the engine to burn the soot. The number of cracks generated in the partition wall on the outlet end face was confirmed, and evaluated as follows. A: No crack is generated, B: One crack is generated, B: Two or three cracks are generated, B: Four or more cracks are generated.

[2-2] Evaluation of soot leakage due to omission of plugging:
After a pressure loss load at 20 Nm ³ / min, RT, a leaked part was identified in the light leakage inspection apparatus and evaluated as follows.
A: No soot leakage occurred, O: One soot leakage occurred, Δ: Soot leakage occurred in 2 to 5 locations, and X: Soot leakage occurred in 6 or more locations.

[3-1] Production of honeycomb structure:
As a raw material, cordierite-forming raw material consisting mainly of talc, kaolin, and alumina, water and binder are mixed, dispersed, mixed, and kneaded, the raw material is extruded into a cylindrical shape by a kneader, and it is an extrusion molding machine. Was extruded to obtain a honeycomb formed body. Then, the obtained honeycomb formed body was dried with a microwave dryer, a hot air dryer or the like. After drying further, it was cut into a predetermined length, and the cell density was 46.5 (pieces / cm ³ ), the partition wall thickness was 305 μm, the shape of the inlet and outlet cells was square, the average pore diameter was 23 μm, the pores A honeycomb structure A having a rate of 52% was prepared. In the same manner as described above, the honeycomb structure B having a partition wall thickness of 254 μm, the shape of the inlet cell and the outlet cell being quadrangular, an average pore diameter of 23 μm, and a porosity of 52%, and the partition wall thickness of 305 μm The shape of the cell and the outlet cell is a quadrangle, the honeycomb structure C having an average pore diameter of 23 μm and a porosity of 58%, the partition wall thickness of 254 μm, the upstream opening area is large, and the downstream opening area is small. And a honeycomb structure D having an average pore diameter of 14 μm and a porosity of 48% was prepared.

[3-2] Preparation of sealing member:
First, a slurry for a plugged portion was prepared. The slurry of this plugging portion is a mixture of SiC powder and metal Si powder as ceramic raw materials, and a foamed resin is added as a pore former, and methyl cellulose and polyethylene oxide, surfactant and water are added respectively. A mixture having the composition shown in Table 2 was prepared, and the mixture was kneaded for 30 minutes using a mixer, and the slurry at the plugged portions of the regions A and B was stored in a storage container.

[3-2-1] Formation of plugging member 1 (formation of a plugged portion in which the region A and the region B are filled with the plugging member):
A mask is applied to the upstream opening end of the dried honeycomb bodies A to D obtained as described above, and the upstream opening is immersed in the storage container so that the mask is not applied. The plugging slurry of region B is filled in the (cell) opening. Further, the plugging slurry filled in the region B is not heat-treated, and the plugging slurry in the region A is filled on the region B to form a plugging portion including the region B and the region A. . Further, with respect to the upstream opening end, a mask is applied to the cells plugged at the downstream opening end, and the plugging slurry in the region B is applied to the cells not plugged at the upstream opening end. A plugging portion is formed by filling, and the cells are alternately closed in a checkered pattern at both ends. Thereafter, the plugged honeycomb formed body was dried with a hot air drier, and further fired (calcined) in an oxidizing atmosphere at 550 ° C. for about 3 hours. Further, firing (main firing) was performed in an Ar inert atmosphere as a firing temperature of about 1400 ° C. to about 1500 ° C.

  Specifically, in the sealed portions formed on the downstream end face of the honeycomb filter of Examples 1 to 9, 11 to 13, and 14 to 21 shown in Table 1 below, the eyes composed of the regions A and B It was formed as a sealed part. Similarly, the honeycombs of Examples 22 to 28 and 30 to 38 shown in Table 2, Examples 39 to 45 and 47 to 55 shown in Table 3, and Examples 56 to 63 and 65 to 67 shown in Table 4 In the plugged portion formed on the downstream end face of the filter, the filter was formed as a plugged portion consisting of the region A and the region B.

[3-2-2] Formation of a sealing member 2 (formation of a sealing portion in which only the region B is filled with the sealing member):
In addition, a mask is applied to the upstream opening end of the dried honeycomb bodies A to D obtained as described above, and the upstream opening is immersed in the storage container so that the mask is not subjected to the downstream opening. The plugging slurry in the region B is filled in the end (cell) opening. Further, the region A is not filled with the plugging slurry, and a plugged portion including the region B and the region A not filled with the plugging material is formed. Further, with respect to the upstream opening end, a mask is applied to the cells plugged at the downstream opening end, and the plugging slurry in the region B is applied to the cells not plugged at the upstream opening end. A plugging portion is formed by filling, and the cells are alternately closed in a checkered pattern at both ends. Thereafter, the plugged honeycomb formed body was dried with a hot air drier, and further fired (calcined) in an oxidizing atmosphere at 550 ° C. for about 3 hours. Further, firing (main firing) was performed in an Ar inert atmosphere as a firing temperature of about 1400 ° C. to about 1500 ° C.

  Specifically, in the plugged portion formed on the downstream end face of the honeycomb filter of Example 10 shown in Table 1 below, a plugged portion composed of a region A and a region B not filled with the plugged portion was formed. . Similarly, in the plugged portion formed on the downstream end face of each honeycomb filter of Example 29 shown in Table 2, Example 46 similarly shown in Table 3, Example 64 shown in Table 4, It was formed as a plugged portion consisting of region A and region B not filled with the plugged portion.

[3-2-3] Formation of plugging member 3 (formation of a plugged portion in which the entire plugged portion is filled with the slurry of region A):
In addition, a mask is applied to the upstream opening end of the dried honeycomb bodies A to D obtained as described above, and the upstream opening is immersed in the storage container so that the mask is not subjected to the downstream opening. The plugging slurry of the region A was filled in the entire plugged portion in the end (cell) opening to form a plugged portion. Further, for the upstream opening end, a mask is applied to the plugged cell at the downstream opening end, and the slurry in the region A is filled into the cells not plugged at the upstream opening end. A plugged portion was formed. Thereafter, the plugged honeycomb formed body was dried with a hot air drier, and further fired (calcined) in an oxidizing atmosphere at 550 ° C. for about 3 hours. Further, firing (main firing) was performed in an Ar inert atmosphere as a firing temperature of about 1400 ° C. to about 1500 ° C.

  Specifically, in the plugged portion formed on the downstream end face of the honeycomb filter of Comparative Example 1 shown in Table 1 below, the entire plugged portion was filled with the slurry of region A to form the plugged portion. Similarly, it was formed as a plugging portion formed on the downstream end face of the honeycomb filter of Comparative Example 3 shown in Table 2, Comparative Example 5 shown in Table 3, and Comparative Examples 7 to 10 shown in Table 4.

[3-2-4] Formation of plugging member 4 (formation of a plugged portion in which the entire plugged portion is filled with the slurry of region B):
In addition, a mask is applied to the upstream opening end of the dried honeycomb bodies A to D obtained as described above, and the upstream opening is immersed in the storage container so that the mask is not subjected to the downstream opening. The plugging slurry in the region B was filled in the entire plugged portion in the end (cell) opening to form a plugged portion. Furthermore, for the upstream opening end, a mask is applied to the cells plugged at the downstream opening end, and the slurry in the region B is filled into the cells not plugged at the upstream opening end. A plugged portion was formed. Thereafter, the plugged honeycomb formed body was dried with a hot air drier, and further fired (calcined) in an oxidizing atmosphere at 550 ° C. for about 3 hours. Further, firing (main firing) was performed in an Ar inert atmosphere as a firing temperature of about 1400 ° C. to about 1500 ° C.

  Specifically, in the plugged portion shown in Table 1 below and formed on the downstream end face of the honeycomb filter of Comparative Example 2, the entire plugged portion was filled with the slurry of region B to form the plugged portion. Similarly, in the plugged portion formed on the downstream end face of the honeycomb filter of Comparative Example 4 shown in Table 2, Comparative Example 6 shown in Table 3, and Comparative Examples 7 to 10 shown in Table 4, the plugged portion The whole area was filled with the slurry of region A to form a plugged portion.

  The above-described evaluation was performed on the honeycomb filters of Examples 1 to 67 and Comparative Examples 1 to 10 obtained through the above steps. The results are shown in Tables 1 to 4, and the thickness ratio and porosity ratio of the region A and the region B in the above-described plugged portion are shown in the same table.

  In addition, in relation to the above, the physical property values of Example 5 and Example 56 below are shown in Tables 5 and 6.

(Discussion)
As shown in Tables 1 to 4, in Examples 1 to 67, crack resistance can be suppressed, and as shown in Table 4, soot leakage due to sealing can be suppressed and good results are obtained. I was able to get it. Therefore, in the honeycomb filter of the example, in the region A, the thermal stress generated on the partition wall outermost surface is suppressed, while in the region B, the porosity of the plugged portion is reduced to improve the pressure bonding strength. It was proved that it was an excellent filter capable of suppressing sealing and soot leakage in the entire sealing part. Specifically, Examples 3 to 10, 11 to 12, 15 to 19 in Table 1, Examples 24 to 30 and 34 to 36 in Table 2, and Examples 41 to 47 and 51 in Table 3 are more preferable. To 53, Examples 56, 57 and 60 to 65 in Table 4. In each of these examples, the region A of the plugged portion has a higher porosity, the porosity of the region B is further decreased, or the region B is formed with a larger thickness. For this reason, the effects of the present invention can be generally achieved. Further, as preferable examples, Examples 1, 2, 13, 14, and 20 in Table 1, Examples 22, 23, 31 to 33, and 37 in Table 2, Examples 40, 48, 50, and 54 in Table 3, 58 and 66 of Table 4 can be mentioned. Although not as much as in the above-described embodiments, the porosity of the plugged portion in the region B having a low porosity while reliably suppressing the thermal stress generated in the partition wall end face in the region A also in these embodiments. It is proved that an excellent effect can be achieved because the pressure-bonding strength is improved by reducing the pressure and the sealing portion can be prevented from being sealed and soot leakage can be suppressed. In addition, in Example 21 of Table 1, Example 38 of Table 2, Examples 39, 49, and 55 of Table 3, and Examples 59 and 67 of Table 4, it explained so far in terms of crack resistance or soot leakage. Although it is inferior to the above-mentioned examples, the results of the experiment show that crack resistance and soot at the time of reproduction are improved in terms of crack resistance or soot leakage compared to conventional products, particularly the comparative examples described later. It seems that leakage can be suppressed.

  On the other hand, as shown in Tables 1 to 4, in Comparative Examples 1 to 10, both crack resistance and soot leakage could not be achieved, and this is particularly apparent from the experimental results of Comparative Examples 7 to 10. is there. Therefore, it was confirmed that the comparative example is difficult to be realized as an implementation product.

  The method for manufacturing a honeycomb filter according to the present invention can be used as a means for manufacturing the honeycomb filter according to the present invention.

  The honeycomb filter according to the present invention removes particulate matter in exhaust gas discharged from internal combustion engines such as automobile engines, construction machine engines, and stationary engines for industrial machines, and other combustion devices, from the exhaust gas. Can be used for

1: honeycomb filter, 2a, 2b: end face, 3: cell (flow hole), 4: partition wall, 6: plugged portion, 7: region A (for plugged portion), 9: region (for plugged portion) B, 11: Open end, 11a: (Downstream) open end, 11b: (Upstream) open end, X: Large pore, Z: Gap.

Claims (10)

It consists of a honeycomb structure provided with a large number of flow holes serving as exhaust gas passages partitioned by partition walls,
The opening end portion formed on the downstream side of the plurality of flow holes and the opening end portion formed on the upstream side are formed with plugged portions alternately sealed, and at least on the downstream side. The formed sealing portion is configured as a sealing portion including a region A having a high porosity and a region B having a low porosity with respect to the porosity of the partition wall ,
The plugged portion formed on the downstream side is formed as a two-layer structure including the region A and the region B,
Furthermore, the plugged portion formed on the upstream side is a plugged portion having a region A having a high porosity and a region B having a low porosity, or a region A having a high porosity, and a low porosity. It is comprised as a plugged part consisting of a two-layer structure of region B consisting of
The region A is formed on the end face side of the honeycomb filter, and the region B is formed apart from the end face side of the honeycomb filter,
Each porosity of the region A and the region B is formed in a stepwise manner,
A honeycomb filter formed as a region having large pores in which the porosity of the region A is not uniform . The porosity of the region A of the plugging portion is, the is at 104% or more with respect to the porosity of the partition walls, the porosity of the region B is 98% or less with respect to the porosity of the partition wall according to claim 1 Honeycomb filter as described in. The honeycomb filter according to claim 1 or 2 , wherein the porosity of the region B is greater than 75% with respect to the porosity of the partition wall. The honeycomb filter according to any one of claims 1 to 3 , wherein a porosity of the region B is larger than 80% of a porosity of the partition wall. The honeycomb filter according to any one of claims 1 to 4 , wherein the thickness of the region B is 20% or more with respect to the thickness of the entire plugged portion. Upstream opening area of the flow holes, while being larger than the outlet opening area, a region A only on the outlet side, to any one of claims 1 to 5, comprising a plugging portion made of region B The honeycomb filter described. The honeycomb filter according to any one of claims 1 to 6 , wherein the honeycomb structure is made of at least one ceramic selected from the group consisting of cordierite, SiC, mullite, aluminum, aluminum titanate, and SiN. A method for manufacturing the honeycomb filter according to any one of claims 1 to 7 , wherein the honeycomb filter is manufactured by forming a plugged portion including a region A having a high porosity and a region B having a low porosity. A method for manufacturing a filter. After the end face of the honeycomb structure is filled with a plugging member having a low porosity, the plugging member having a high porosity is further filled, and heat treatment of the plugging portion is performed once. A method for manufacturing a honeycomb filter according to claim 8 . 9. The manufacturing method according to claim 8 , wherein the end face of the honeycomb structure is filled with a plugging member having a low porosity and then dried, and further, the plugging member having a high porosity is filled and heat treatment is performed. The manufacturing method of the honeycomb filter of description.

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