JP6530217B2 - Honeycomb structure - Google Patents

Description

  The present invention relates to a honeycomb structure. More specifically, the present invention relates to a honeycomb structure having a pressure drop that is unlikely to rapidly increase even when used for a long time, has a good collection efficiency, and has a sufficient isostatic strength.

  Conventionally, diesel engines generate particulate matter (hereinafter sometimes referred to as "PM") by combustion, and the particulate matter has been recognized as carcinogenic. Therefore, it is essential to prevent the particulate matter from being released to the atmosphere. Therefore, in addition to the conventional regulation of particulate emissions by weight, strict regulations are imposed to regulate the number of particulates.

  Here, there is a limit to the reduction of particulate matter emissions due to the improvement of combustion, and the installation of a filter in the exhaust is currently the only effective means. As this filter, a wall flow type filter designed to allow gas to pass through porous partition walls is effective. Specifically, as a wall flow type filter, there is known a honeycomb structure in which cells serving as a fluid flow path are alternately plugged on the inflow end face side and the outflow end face side, and exhaust gas is allowed to flow through the partition walls. (See Patent Document 1).

Unexamined-Japanese-Patent No. 2003-254034

  In the filter (honeycomb structure) described in Patent Document 1, particulate matter is deposited in the filter by being used for a long time. In this filter, the deposited particulate matter may cause clogging of the filter, which may cause a phenomenon in which the pressure loss of the filter may rapidly increase (see FIG. 7). Therefore, it has been difficult to use the above filter in applications where it is necessary to minimize the increase in pressure loss. That is, the application of the above-described filter is limited.

  Therefore, there has been a demand for development of a filter (honeycomb structure) in which a rapid increase in pressure loss hardly occurs even when used for a long time, the collection efficiency is good, and sufficient isostatic strength is secured.

  The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a honeycomb structure having a pressure drop that is unlikely to rapidly increase even when used for a long time, has a good collection efficiency, and has a sufficient isostatic strength.

  According to the present invention, a honeycomb structure shown below is provided.

[1] A honeycomb structure portion having porous partition walls defining a plurality of cells serving as a fluid flow path extending from an inflow end surface which is one end surface to an outflow end surface which is the other end surface; an inflow end surface side of the end portion inflow side plugged portion disposed, with said outflow end face side of the end portion disposed in the outflow side plugged portions of the cells of the remaining honeycomb structure Ru comprising a body In the honeycomb structure, 1 to 7 holes having openings in side surfaces are formed, and the diameter of the openings of the holes is 3 to 50 mm, and the end face of the honeycomb structure is The value of the sum of the depths of the holes with respect to the value of half of the maximum length is 1 to 14, and the side surfaces of the honeycomb structure portion cover all of the openings of all the holes. Further comprising an outer peripheral wall disposed and made of the same material as the honeycomb structure Honeycomb structure.

[2] The honeycomb structure according to the above [1], wherein two or more holes are formed, and in all the holes, the distance between the closest holes is 10 to 50 mm.

[3] The honeycomb structure according to the above [1] or [2], wherein all the holes are deeper than half the maximum length of the end face of the honeycomb structure body.

[4] A plane in which two or more holes are formed, orthogonal to the central axis of the honeycomb structure and facing the inflow end face of the honeycomb structure is defined as an end-side projection plane, and the central axis of the honeycomb structure Assuming that the hole portion of the honeycomb structure is projected from the direction to the end surface side projection surface, all the hole portions projected onto the end surface side projection surface have a central axis of one of the hole portions. The angle formed with the central axis of the other hole is 45 °, or all the holes projected on the end-side projection plane are the central axis of one of the holes and the other hole The honeycomb structure according to any one of the above [1] to [3], wherein the angle formed with the central axis of the part is 90 °.

[5] A plane in which two or more holes are formed, orthogonal to the central axis of the honeycomb structure and facing the inflow end face of the honeycomb structure is defined as an end-side projection plane, and the central axis of the honeycomb structure Assuming that the hole portion of the honeycomb structure is projected from the direction to the end surface side projection surface, all the hole portions projected onto the end surface side projection surface have the central axes parallel to each other. The honeycomb structure in any one of 1]-[3].

[6] Two or more holes are formed, and the honeycomb structure portion has a cylindrical shape, and in the outflow end face of the honeycomb structure portion, a direction orthogonal to the thickness direction of the partition walls is taken as an X axis, the X Assuming a coordinate axis having a direction orthogonal to the axis as the Y axis and a central axis of the honeycomb structure as the Z axis, the length of the honeycomb structure in the central axis direction is L, and The radius at the outflow end surface is R, and a plane orthogonal to the Y axis is a side projection plane, and the opening of the hole of the honeycomb structure is projected from the direction of the Y axis to the side projection plane Center of the openings of all the holes projected onto the side projection surface is formed between L / 2 to 3L / 4 in the Z-axis direction and in the X-axis direction. Is between -3R / 4 and + 3R / 4 The formed [1] to the honeycomb structure according to any one of [5].

[7] The honeycomb structure according to any one of the above [1] to [6], wherein the opening of the hole is closed.

[8] The outer peripheral wall disposed so as to cover the surface of the blocking material that blocks the opening of the hole with a blocking material and covers the side surface of the honeycomb structure and the opening of the hole. The honeycomb structure according to any one of the above [1] to [7].

  In the honeycomb structure of the present invention, the hole portion opened in the side surface of the honeycomb structure portion is formed. Therefore, in the honeycomb structure of the present invention, a rapid increase in pressure loss hardly occurs even when used for a long time, the collection efficiency is good, and sufficient isostatic strength is secured.

It is a perspective view which shows typically one Embodiment of the honeycomb structure of this invention. FIG. 3 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction in the one embodiment of the honeycomb structure of the present invention. It is a top view which shows typically the honeycomb structure in the other embodiment of the honeycomb structure of this invention, and the end surface side projection surface. 5 is a schematic view for explaining the position of the opening of the hole formed in the honeycomb structure of Example 1. FIG. FIG. 26 is a schematic view for explaining the position of the opening of the hole formed in the honeycomb structure of Example 8; It is a graph which shows the use time in the honeycomb structure of this invention, and the relationship of a pressure loss. It is a graph which shows the use time in the conventional honeycomb structure, and the relationship of a pressure loss.

  Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments, and appropriate changes, improvements, etc. can be added to the following embodiments based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that what has been described is also within the scope of the present invention.

[1] Honeycomb structure:
One embodiment of a honeycomb structure of the present invention is a honeycomb structure 100 shown in FIG. 1 and FIG. The honeycomb structure 100 includes a honeycomb structure portion 10 having porous partition walls 1, an inflow side plugged portion 3, and an outflow side plugged portion 4. The honeycomb structure portion 10 has a partition wall 1 which partitions and forms a plurality of cells 2 serving as a fluid flow path extending from the inflow end surface 11 which is one end surface to the outflow end surface 12 which is the other end surface. Further, the inflow side plugging portion 3 is disposed at an end portion of the predetermined cell 2 on the inflow end surface 11 side. Further, the outlet-side plugging portion 4 is disposed at the end of the remaining cell 2 on the outlet end 12 side. In the honeycomb structure portion 10, 1 to 7 hole portions 30 each having an opening 30a on the side surface 5 are formed. The opening diameter D of the opening 30a of the hole 30 is 3 to 50 mm. In the honeycomb structure 100, the value of the sum of the depths of the hole portions 30 is 1 to 14 with respect to the half value of the maximum length of the end face of the honeycomb structure body 10. The honeycomb structure 100 further includes an outer peripheral wall 20 which is disposed on the side surface of the honeycomb structure 10 so as to cover the entire openings 30a of all the holes 30 and is made of the same material as the honeycomb structure . .

  By adopting the above-described configuration, such a honeycomb structure 100 can prevent clogging caused by accumulation of particulate matter after prolonged use, and it is difficult for rapid increase in pressure loss to occur. is there. That is, as shown in FIG. 7, in the conventional wall flow type filter, when PM in exhaust gas is removed for a long time (predetermined time T), the cell 2 of this filter is blocked by PM, and the pressure loss is Will soar. As described above, in order to prevent the pressure loss from rising rapidly, PM is removed by periodically burning PM, and the filter is regenerated. However, as the number of times of filter regeneration increases, the fuel efficiency of the engine deteriorates. In addition, removing PM in the filter without regeneration is time-consuming. On the other hand, according to the honeycomb structure 100, even when it is used for a long time (that is, when the predetermined time T has elapsed), the rapid increase of the pressure loss is prevented (see FIG. 6). Further, since the honeycomb structure 100 is a wall flow type filter, the PM collection efficiency is good. In addition, generally, when a space such as the hole 30 is formed inside the honeycomb structure, it is also assumed that the isostatic strength decreases. However, the honeycomb structure 100 has sufficient isostatic strength. As described above, the honeycomb structure 100 can prevent a rapid increase in pressure loss for a long period of time, can obtain excellent collection efficiency, and can sufficiently ensure isostatic strength.

  FIG. 1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction in one embodiment of the honeycomb structure of the present invention.

[1-1] Honeycomb structure part:
In the honeycomb structure portion 10, a hole 30 having an opening 30a is formed on the side surface 5 thereof. By forming the hole, a part of the exhaust gas flowing in from the inflow end surface is discharged without passing through the partition wall. That is, some of the exhaust gas flowing into the inflow cell 2a (see FIG. 2) flows into the hole 30. Then, the exhaust gas flowing into the hole 30 may be discharged as it is from the outflow cell 2 b (see FIG. 2) connected to the hole 30. Thus, in the honeycomb structure 100, there is a path through which part of the exhaust gas is discharged without passing through the partition walls. Therefore, even if the partition wall is in a state of causing clogging by continuing to collect PM for a long period of time, the pressure loss can be prevented from rapidly rising due to the presence of the above path. In addition, the existence of the above-mentioned path takes a long time until the partition wall becomes clogged, and even if the pressure loss suddenly rises, the occurrence time can be significantly delayed.

  The shape of the opening of the hole may be a circle, an ellipse, or a polygon such as a triangle or a square. Among these, the shape of the opening of the hole is preferably circular from the viewpoint of easily forming the hole.

  Here, in the present specification, the hole is a concept that does not include a slit (groove). Specifically, the hole preferably has a ratio of the major axis to the ratio of the major axis (minor axis) orthogonal to the major axis (major axis / minor axis) to 1 to 2. The major axis is the longest of the line segments connecting two different points on the outer edge of the opening of the hole.

  The opening diameter of the opening of the hole is 3 to 50 mm, preferably 10 to 40 mm, and more preferably 20 to 30 mm. By setting the pressure in such a range, it is possible to prevent a sudden increase in pressure loss for a long period of time, good collection efficiency can be obtained, and furthermore, sufficient isostatic strength can be secured. When the opening diameter of the hole opening is less than the lower limit value, it is not possible to prevent a sudden increase in pressure loss for a long time. In addition, as with the conventional honeycomb structure (in which no hole portion is formed), it is not possible to prevent a sudden increase in pressure loss for a long time. If it exceeds the upper limit value, the amount of PM flowing out from the hole increases, so that the PM collection efficiency becomes insufficient. The “opening diameter of the opening” refers to the length of the longest one of line segments connecting two different points on the outer edge of the opening.

  In the honeycomb structure of the present invention, the value of the sum of the depths of the holes (the ratio of depth / length) to the value of half the maximum length of the end face of the honeycomb structure portion is 1 to 14, 3 It is preferably 12 and more preferably 5 to 10. By setting the pressure in such a range, it is possible to prevent a sudden increase in pressure loss for a long period of time, good collection efficiency can be obtained, and furthermore, sufficient isostatic strength can be secured. If the ratio of depth / length is less than the lower limit value, it is not possible to prevent a sudden increase in pressure loss for a long time. If it exceeds the upper limit value, the amount of PM flowing out from the hole increases, so that the PM collection efficiency becomes insufficient. The "depth of the hole" refers to the depth of the deepest portion of the hole.

  The number of holes is 1 to 7, preferably 2 to 6, and more preferably 3 to 5. By setting the pressure in such a range, it is possible to prevent a sudden increase in pressure loss for a long period of time, good collection efficiency can be obtained, and furthermore, sufficient isostatic strength can be secured. If the number of holes is zero (i.e., no holes are formed), it is not possible to prevent a sudden increase in pressure loss for a long time. If the number of holes is more than 7, the PM collection efficiency is not sufficient.

  Preferably, all the holes are deeper than half of the maximum length at the end face of the honeycomb structure. By doing this, PM passing through the hole can be increased to suppress PM deposition. Therefore, it is possible to prevent a sudden increase in pressure loss for a long time. If there is a hole shallower than half of the maximum length at the end face of the honeycomb structure part, there is a possibility that the rapid increase in pressure loss can not be prevented for a long time.

  When two or more holes are formed, the distance between the nearest holes of all the holes is preferably 10 mm or more, more preferably 15 mm or more, and still more preferably 20 mm or more . The upper limit is preferably 50 mm. By setting the distance to such a range, the isostatic strength of the honeycomb structure can be favorably secured. If the distance is outside the above range, the isostatic strength of the honeycomb structure may not be sufficiently secured. The “distance between closest holes” means the shortest distance with the close hole when the closest hole (proximity hole) is determined in each of the two or more holes formed. It means the distance.

  When two or more holes are formed, it is preferable to satisfy the following conditions (i) or (ii). That is, first, as shown in FIG. 3, a plane orthogonal to the central axis O of the honeycomb structure 10 and facing the inflow end surface 11 of the honeycomb structure 10 is referred to as an end-side projection surface 41. Then, it is assumed that the hole 30 of the honeycomb structure 10 is projected from the direction of the central axis O of the honeycomb structure 10 to the end surface side projection surface 41. At this time, condition (i): The angle between the central axis of one hole 30 and the central axis of the other hole 30 is 45 ° in all the holes 30 projected on the end surface side projection surface 41 . Or condition (ii): The angle between the central axis of one hole 30 and the central axis of the other hole 30 is 90 ° in all the holes 30 projected on the end surface side projection surface 41. FIG. 3 is a plan view schematically showing a honeycomb structure and an end face side projection surface in another embodiment of the honeycomb structure of the present invention.

  By satisfying such conditions, exhaust gas can be uniformly taken into the hole, and PM deposition in the hole becomes uniform. Therefore, it is possible to prevent a sudden increase in pressure loss for a long time.

  In addition, the holes (one hole and the other hole) satisfying the condition (i) or (ii) may not be adjacent to each other. That is, when projected onto the end face side projection plane, the central axes of the respective hole portions may satisfy the above-mentioned angle, and there is no particular limitation on the positional relationship in the cell extending direction of the honeycomb structure.

  The holes satisfying the condition (i) or (ii) (one hole and another hole) may intersect with each other so as to share a part of the space. When they intersect with each other as described above, exhaust gas can be uniformly taken into the holes, and the deposition of PM in the holes becomes uniform. Therefore, it is possible to prevent a sudden increase in pressure loss for a long time.

  The holes satisfying the condition (i) or (ii) (one hole and another hole) may intersect without sharing a space. That is, the holes satisfying the condition (i) or (ii) may be in a three-dimensional crossing relationship. When the intersection is made in this manner, the strength reduction caused by the intersection when sharing a space is improved, so that the isostatic strength can be secured.

  When two or more holes are formed, the following condition (a) is preferably satisfied. That is, first, a plane orthogonal to the central axis of the honeycomb structure part and facing the inflow end face of the honeycomb structure part is taken as an end face side projection plane. Then, it is assumed that the hole portion of the honeycomb structure portion is projected from the central axis direction of the honeycomb structure portion to the end surface side projection surface. At this time, condition (a): central axes of all the holes projected on the end face side projection plane are parallel to each other.

  By satisfying such a condition, the strength reduction caused by the intersection when sharing a space is improved, and the isostatic strength can be secured.

  Moreover, when two or more hole parts are formed and the honeycomb structure part has a cylindrical shape, it is preferable to satisfy the following condition (α). That is, first, as shown in FIGS. 4 and 5, in the outflow end face 12 of the honeycomb structure 10, a direction orthogonal to the thickness direction of the partition walls is taken as an X axis, and a direction orthogonal to the X axis is taken as a Y axis. . Furthermore, the central axis O of the honeycomb structure portion 10 is taken as the Z axis. Such coordinate axes are assumed. Next, the length in the central axis O direction of the honeycomb structure 10 is L, and the radius at the outflow end face 12 of the honeycomb structure 10 is R. Further, it is assumed that a plane orthogonal to the Y axis is a side projection plane, and that the opening 30a of the hole 30 of the honeycomb structure 10 is projected from the direction of the Y axis to the side projection plane. At this time, the condition (α): the centers of the openings 30a of all the holes 30 projected on the side projection surface are formed between L / 4 and 3L / 4 in the Z-axis direction, and in the X-axis direction Is formed between -3R / 4 and + 3R / 4.

  By satisfying such conditions, exhaust gas can be uniformly taken into the hole, and PM deposition in the hole becomes uniform. Therefore, it is possible to prevent a sudden increase in pressure loss for a long time.

  FIG. 4 is a schematic view for explaining the position of the opening of the hole formed in the honeycomb structure of the first embodiment. FIG. 5 is a schematic view for explaining the position of the opening of the hole formed in the honeycomb structure of Example 8. As shown in FIG.

  The shape of the honeycomb structure part is not limited to a cylindrical shape. For example, it can be made into polygonal pillars, such as triangular pillars and square pillars, elliptical pillars, etc.

  The thickness of the partition wall is preferably 50.8 to 508.0 μm, more preferably 203.2 to 381.0 μm, and particularly preferably 254.0 to 304.8 μm. If the thickness of the partition wall is less than the lower limit value, the collection efficiency may be reduced. If it exceeds the upper limit value, pressure loss may increase.

  The porosity of the partition walls is preferably 40 to 70%, more preferably 42 to 65%, and particularly preferably 48 to 59%. If the porosity is less than the lower limit value, the pressure loss may increase. If the upper limit value is exceeded, the strength of the honeycomb structure is lowered, and there is a possibility that the honeycomb structure may be broken during canning. The porosity is a value measured by a mercury porosimeter.

  The material of the partition wall is preferably ceramic, and cordierite, silicon carbide, silicon-silicon carbide based composite material, mullite, alumina, aluminum titanate, silicon nitride, and silicon carbide-cordierite from the viewpoints of excellent strength and heat resistance. Further preferred is at least one selected from the group consisting of composite materials. Of these, cordierite is particularly preferred.

  The length in the extending direction of the cells of the honeycomb structure can be 101.6 to 228.6 mm.

  The honeycomb structure 100 may further include an outer peripheral wall 20 (see FIG. 1) on the side surface 5 of the honeycomb structure body 10. The outer peripheral wall 20 is preferably disposed to cover the side surface 5 of the honeycomb structure 10 and the opening 30 a of the hole 30. By disposing the outer peripheral wall 20 in this manner, the surface of the outer peripheral wall 20 is smooth, so that it is possible to prevent the holding member from rubbing against the honeycomb structure 100 and the honeycomb structure from being deteriorated. Here, the closing member may be disposed in the hole so as to close the opening of the hole. And the outer peripheral wall 20 can be arrange | positioned on the surface (exposed surface) of this closure material. The hole may be closed without using the closing member. That is, when the opening diameter of the opening of the hole is 30 mm or less, the outer peripheral wall 20 can be disposed without using the closing member.

  The thickness of the outer peripheral wall 20 is preferably 0.5 to 4.0 mm, more preferably 0.8 to 3.0 mm, and particularly preferably 1.0 to 2.0 mm. If the thickness of the outer peripheral wall is less than the lower limit value, the collection efficiency may be reduced. When the volume of the entire honeycomb structure 100 is constant, the cross-sectional area of the honeycomb structure decreases by the amount of the outer peripheral wall. Therefore, pressure loss may increase.

[1-2] Plugging part:
The honeycomb structure of the present invention includes the inflow side plugged portion and the outflow side plugged portion. The material of these plugging portions can be the same as the above-described partition wall.

  Further, the depths of the inflow side plugging portion and the outflow side plugging portion can be determined as appropriate.

[2] Manufacturing method of honeycomb structure:
The manufacturing method of the honeycomb structure of the present embodiment will be described. First, a clay for producing a honeycomb structure is prepared, and the clay is formed to produce a honeycomb formed body (forming step). Thereafter, the obtained honeycomb molded body (or dried honeycomb dried body as required) is subjected to plugging and the plugging portions (inflow side plugging portion and outflow side plugging portion) (Plugging portion forming step). Thereafter, the honeycomb fired body is manufactured by firing. Thereafter, holes are formed in the side surfaces of the honeycomb fired body to form holes. Thus, a honeycomb structure can be obtained (honeycomb structure producing step). In addition, it is also possible to make a hole in the side surface of the honeycomb formed body before firing to form a hole.

  Hereinafter, each manufacturing process will be described in more detail.

[2-1] Forming process:
First, in the forming step, a ceramic forming raw material containing a ceramic raw material is formed to form a honeycomb formed body in which a plurality of cells serving as fluid channels are sectioned.

  The ceramic raw material contained in the ceramic forming raw material is preferably one containing at least one selected from the group consisting of cordierite-forming raw materials, cordierite, mullite, alumina, titania, silicon carbide, and aluminum titanate. The cordierite-forming raw material is a ceramic raw material compounded so as to have a chemical composition in which 42 to 56% by mass of silica, 30 to 45% by mass of alumina, and 12 to 16% by mass of magnesia are contained. And are fired to become cordierite.

  The ceramic forming material is preferably prepared by mixing the above-mentioned ceramic material with a dispersion medium, an organic binder, an inorganic binder, a pore former, a surfactant and the like. The composition ratio of each raw material is not particularly limited, and it is preferable to set the composition ratio according to the structure, material, and the like of the honeycomb structure to be produced.

  When forming the ceramic forming raw material, it is preferable to knead the forming raw material first to make a clay, and to form the obtained clay into a honeycomb shape. There is no restriction | limiting in particular as a method of knead | mixing a forming raw material and forming clay, For example, the method of using a kneader, a vacuum soil kneader, etc. can be mentioned. There is no restriction | limiting in particular as a method of shape | molding a clay, and forming a honey-comb molded object, Conventionally well-known shaping | molding methods, such as extrusion molding and injection molding, can be used. For example, a method of forming a honeycomb formed body by extrusion using a die having a desired cell shape, partition wall thickness and cell density can be mentioned as a preferable example.

  When forming a hole in the honeycomb formed body before firing, the hole can be formed in the honeycomb formed body using an drilling tool such as a drill. As described above, by forming the hole to be the hole at the stage of the honeycomb formed body before firing, it is possible to suppress the crack generated at the time of forming the hole.

  The shape of the honeycomb formed body is not particularly limited, and a cylindrical shape, an oval cross-section perpendicular to the central axis, a racetrack shape, a triangular, quadrangular, pentagonal, hexagonal, octagonal or other polygonal columnar shape may be mentioned. Can.

  The obtained honeycomb molded body may be dried. The drying method is not particularly limited, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like, among which dielectric drying, microwave drying or It is preferred to carry out hot air drying alone or in combination.

[2-2] Plugging part formation process:
Next, the plugged portions are formed on the honeycomb formed body (in the case of employing the drying step, the honeycomb dried body). Specifically, first, a mask is applied so that the inflow cell 2a (see FIG. 2) is covered on the inflow end face of the honeycomb formed body, and the end (inflow end) to which the mask is applied is made into plugging slurry. Immerse and fill the opening of the unmasked outlet cell with the plugging slurry. Thereafter, a mask is applied to the outflow end face of the honeycomb formed body so as to cover the outflow cell 2b (see FIG. 2), and the masked end (outflow end) is immersed in the plugging slurry to obtain a mask The plugging slurry is filled in the opening of the inflow cell not subjected to Thus, a honeycomb formed body in which the plugged portion is formed can be obtained.

  The plugging slurry can be appropriately selected and used as the material of the plugging portion of the conventionally known honeycomb structure.

[2-3] Honeycomb Structure Preparation Step:
Next, the obtained honeycomb molded body is fired to obtain a honeycomb fired body. Thereafter, holes are made in the side surfaces of the obtained honeycomb fired body to form holes, and a honeycomb structure is manufactured.

  In addition, before firing (final firing) the honeycomb formed body, the honeycomb formed body is preferably calcined. The calcination is carried out for degreasing, and the method is not particularly limited as long as organic substances (organic binder, dispersant, pore former, etc.) can be removed. Generally, the combustion temperature of the organic binder is about 100 to 300 ° C., and the combustion temperature of the pore forming material is about 200 to 800 ° C. Therefore, the calcination condition is about 200 to 1000 ° C. in an oxidizing atmosphere, It is preferable to heat for about 100 hours.

  For firing (main firing) of the honeycomb formed body, appropriate conditions may be selected. For example, in the case of using cordierite-forming raw materials, the firing temperature is preferably 1410 to 1440 ° C. The firing time is preferably 4 to 6 hours as the keeping time at the maximum temperature.

  A drilling tool such as a drill can be employed as a means for making a hole in the side surface of the honeycomb fired body. Thus, when making a hole to be a hole at the stage of the honeycomb fired body, it is not necessary to consider the change in diameter of the hole due to the shrinkage of the honeycomb formed body at the time of firing.

  Further, when the outer peripheral wall is provided, the plugging material is applied to the side surface of the honeycomb fired body so as to cover the opening of the hole after the firing, and then the side surface is coated with the outer peripheral coating material and dried to form the outer peripheral wall It is preferable to do. As the plugging material, one that satisfies the same conditions as the material of the honeycomb structure can be used. Further, as the outer periphery coating material, those used to form the outer peripheral wall of the conventionally known honeycomb structure can be appropriately adopted. In addition, if the opening diameter (hole diameter) of the hole is 30 mm or less, the hole (opening of the hole) can be covered only with the outer peripheral coating material without using the blocking material.

  EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Example 1
13 parts by mass of a pore forming material, 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, respectively, mixed and kneaded The soil was prepared. Alumina, aluminum hydroxide, kaolin, talc and silica were used as cordierite-forming materials. Water was used as a dispersion medium, hydroxypropyl methylcellulose was used as an organic binder, and ethylene glycol was used as a dispersant.

  Next, the clay was extruded using a predetermined mold to obtain a honeycomb molded body having a rectangular cross section of the cells and a cylindrical overall shape.

  Next, the honeycomb formed body was dried by a microwave drier and further completely dried by a hot air drier, and both end surfaces of the honeycomb formed body were cut and adjusted to predetermined dimensions.

  Plugging portions were formed on the dried honeycomb molded body (honeycomb dried body). Specifically, first, the inflow end face of the dried honeycomb body is masked so as to cover the inflow cell (predetermined cell), and the end (inflow end) subjected to the mask is immersed in the plugging slurry Then, the opening of the unmasked outlet cell was filled with the plugging slurry. After that, a mask is applied to the outlet end face of the dried honeycomb body so that the outlet cells (remaining cells) are covered, and the masked end (the outlet end) is immersed in the plugging slurry to form a mask. The plugging slurry was filled into the opening of the inflow cell not applied. Thereafter, the honeycomb formed body in which the plugged portions were formed was dried by a hot air drier. Thus, a plugged honeycomb dried body was obtained.

  Next, the plugged honeycomb dried body was degreased by heating at 450 ° C. for 5 hours, and further firing was performed by heating at 1425 ° C. for 7 hours to obtain a honeycomb fired body.

  Next, from the side of the obtained honeycomb fired body, five holes were formed using a drill.

  In the outflow end face of the honeycomb structure portion (honeycomb fired body), a direction orthogonal to the thickness direction of the partition walls is taken as an X axis, and a direction orthogonal to the X axis is taken as a Y axis. Furthermore, a coordinate axis with the central axis of the honeycomb structure part as the Z axis is assumed. And let L be the length in the central axis direction of the honeycomb structure part and R be the radius at the outflow end face of the honeycomb structure part. Then, a plane orthogonal to the Y axis is taken as a side projection surface. Furthermore, it is assumed that the opening of the hole of the honeycomb structure portion is projected from the Y-axis direction to the side surface side projection surface. At this time, the openings of all the holes projected on the side-surface-side projection plane were at the L / 2 position in the Z-axis direction. Moreover, it was a position of -2R / 3, -R / 3, 0, + R / 3, + 2R / 3 in the X-axis direction (refer FIG. 4). In addition, these positions are center positions of the opening of a hole.

  Then, a plane orthogonal to the central axis of the honeycomb structure part and facing the inflow end face of the honeycomb structure part is taken as an end face side projection plane. In addition, it is assumed that the hole portion of the honeycomb structure portion is projected onto the end face side projection plane from the central axis direction of the honeycomb structure portion. At this time, all the holes projected on the end face side projection plane are formed such that the central axes are parallel to each other.

  Moreover, all the hole parts were through holes penetrating the honeycomb structure part.

  Furthermore, the diameter of the openings in all the holes was 20 mm. And the value of the sum total of the depth of a hole was 8.75 mm to the value of half of the length in the end face of a honeycomb structure part. All holes had a distance of 10 mm or more between the closest holes (see Table 1).

  The openings of all the holes were filled with a plugging material to close the holes. As the plugging material, a slurry containing cordierite particles, ceramic fibers and colloidal oxide was used, and after the plugging material was filled in the opening of the hole, it was dried at 200 ° C. for 2 hours. The depth of the occluder was 1.0 mm.

  Next, the outer peripheral portion of the honeycomb structure portion is ground, and then the outer peripheral coat material is applied on the side surface of the honeycomb structure portion and the surface of the plugging material, and dried to form the outer peripheral wall; Obtained. As the outer periphery coating material, a slurry containing a cordierite-forming material, water, alcohol, and an organic binder was used.

The honeycomb structure had an end surface diameter of 143.8 mm and a length of 152.4 mm in the cell extending direction. Moreover, the thickness of the partition was 304.8 micrometers. In addition, the cell density was 47 cells / cm ² .

  With respect to the obtained honeycomb structure, evaluation of “a sudden increase in pressure loss”, “collection efficiency”, and “isostatic strength ratio” was performed by the following method. The results are shown in Table 2.

[Surge of pressure loss]
The sudden increase in pressure loss of the honeycomb structure was evaluated as follows. First, exhaust gas discharged from a diesel engine (3.0 liters, direct injection common rail, in-line six cylinders) is allowed to flow into the honeycomb structure to start the test. That is, the exhaust gas at 200 ° C. was allowed to flow into the honeycomb structure at a flow rate of 3.0 Nm ³ / min, and the pressure on the inflow end face side and the outflow end face side of the honeycomb structure was measured. And pressure loss (kPa) was calculated | required by computing these pressure differences.

  According to the above evaluation, the case where the time for which the pressure loss after the start of the test is 20 times or more of the initial pressure loss is 40 hours or more is "A". The case where the time for which the pressure loss after the start of the test is 20 times or more of the initial pressure loss is 30 hours or more and less than 40 hours is referred to as "B". The case where the time for which the pressure loss after the start of the test is 20 times or more of the initial pressure loss is 20 hours or more and less than 30 hours is "C". The time when the pressure loss after the start of the test is 20 times or more of the initial pressure loss is less than 20 hours is called "D". The results are shown in Table 2. The above-mentioned “initial pressure loss” is an average value of pressure loss values measured for 30 seconds immediately after the start of the test.

Collection efficiency
The collection efficiency of the honeycomb structure was calculated as follows. First, soot is generated using a burner fueled with light oil. A predetermined amount of air is mixed with the combustion gas such 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 to start the test. The temperature of the mixed gas is 200 ° C. so that the concentration of particulate matter in the mixed gas is 4 g / hour. Sampling was carried out 120 seconds after the start of the test. The collection efficiency was calculated by the following method.

  The exhaust gas is sampled for 60 seconds by a vacuum pump from a piping for sampling provided on the outflow side of the honeycomb structure. Then, when sampling the exhaust gas, the exhaust gas is passed through the holder in which the filter paper is set. Thereby, PM is collected on filter paper. In addition, the mass of filter paper is measured beforehand. The mass of PM in exhaust gas sampled from the upstream side of the honeycomb structure (the mass of PM collected on filter paper) and the mass of PM in exhaust gas sampled from the downstream side of the honeycomb structure (filter paper From the mass of PM), the collection efficiency (%) is calculated. Specifically, the collection efficiency (%) is determined by the following equation (1). When the collection efficiency is 50% or more, the honeycomb structure can be favorably used as a filter for collecting particulate matter in exhaust gas.

Collection efficiency (%) = {(PM mass A−PM mass B) / PM mass A} × 100 (1)
(However, in the above formula (1), “PM mass A” indicates the mass (g) of PM collected on the filter paper on the upstream side (inflow end surface side) of the honeycomb structure “PM mass B” is The mass (g) of PM collected on the filter paper on the downstream side (outflow end side) of the honeycomb structure is shown.

  If the collection efficiency calculated by the above equation (1) is 70% or more is "A", and if 60% or more and less than 70% is "B", it is 50% or more and less than 60%. The case is "C" and the case of less than 50% is "D". The results are shown in Table 2.

[Isostatic strength ratio]
The measurement of isostatic strength was performed based on the isostatic breaking strength test prescribed by M505-87 of the automobile standard (JASO standard) published by Japan Society of Automotive Engineers of Japan. The isostatic fracture strength test is a test in which a honeycomb structure is put in a rubber cylindrical container, a lid made of an aluminum plate is used, and isostatic pressing is performed in water. That is, the isostatic breaking strength test is a test that simulates the compressive load weight when the outer peripheral surface of the honeycomb structure is gripped by the can. The isostatic strength measured by this isostatic breaking strength test is indicated by a pressure value (MPa) when the honeycomb structure breaks. And an isostatic strength ratio was computed on the basis of the isostatic strength of the honeycomb structure of comparative example 18 in which a hole is not formed. In addition, when measuring the intensity | strength of the honeycomb structure which has not sealed the hole part, the rubber plug was inserted in the hole part. The rubber plug inserted into the hole had the same shape and the same diameter as the opening of the hole. The rubber stopper used had a hardness of 90. The hardness of the rubber plug is a durometer A hardness measured in accordance with Japanese Industrial Standard (JIS) K6253.

  The isostatic strength ratio is "A" when it is 0.98 or more, "B" when it is 0.95 or more and less than 0.98, and it is 0.90% or more and less than 0.95. Was designated as "C", and the case of less than 0.9 was designated as "D". The results are shown in Table 2.

  In Table 1, "the opening diameter of the opening of the hole" indicates the opening diameter of the opening of each hole. That is, for example, in Example 1 described as "20 mm" indicates that the opening diameter of all the openings of the five holes is 20 mm. In Table 2, "crossing angle" indicates an angle formed by the central axes of the holes in the end-side projection plane. “Sealing of hole” indicates whether or not the opening of the hole is closed. That is, the case where the opening of the hole is closed is shown as "sealed", and the case where the opening of the hole is not closed is shown as "not sealed".

(Examples 2 to 19, 21, Reference Example 20, Comparative Examples 1 to 19)
In the same manner as in Example 1 except that changes were made as shown in Tables 1 to 4, evaluations of "a sharp rise in pressure loss", "collection efficiency", and "isostatic strength ratio" were performed. The results are shown in Tables 2 and 4.

From Tables 1 to 4, it is difficult for the honeycomb structures of Examples 1 to 19 and 21 and Reference Example 20 to have a rapid rise in pressure loss even when used for a long time as compared with the honeycomb structures of Comparative Examples 1 to 19. It can be seen that the collection efficiency is good and sufficient isostatic strength is secured.

  The honeycomb structure of the present invention can be employed as a filter for purifying exhaust gas discharged from an automobile or the like.

1: Partition wall, 2: Cell, 2a: Inflow cell, 2b: Outflow cell, 3: Inflow side plugging, 4: Outflow side plugging, 5: Side, 10: Honeycomb structure, 11: Inflow end 12: outflow end face, 20: outer peripheral wall, 30: hole, 30a: opening, 41: end face side projection surface, 100: honeycomb structure, D: opening diameter, O: central axis.

Claims (8)

A honeycomb structure portion having porous partition walls defining a plurality of cells serving as a flow path of fluid extending from an inflow end surface which is one end surface to an outflow end surface which is the other end surface; and end the inflow side plugged portions disposed in the outflow side plugged portions said being disposed at an end of the outflow end face side of the cell remaining, a honeycomb structure Ru provided with,
In the honeycomb structure portion, 1 to 7 holes having openings on the side surfaces are formed,
The opening diameter of the opening of the hole is 3 to 50 mm,
The value of the sum of the depths of the holes is 1 to 14 with respect to the half of the maximum length of the end face of the honeycomb structure body,
A honeycomb structure further comprising an outer peripheral wall which is disposed on the side surface of the honeycomb structure portion so as to cover the entire opening of all the hole portions and which is made of the same material as the honeycomb structure.   2. The honeycomb structure according to claim 1, wherein two or more of the holes are formed, and in all the holes, a distance between the closest holes is 10 mm or more.   The honeycomb structure according to claim 1 or 2, wherein all the holes are deeper than half the maximum length of the end face of the honeycomb structure. Two or more holes are formed,
A plane orthogonal to the central axis of the honeycomb structure and facing the inflow end face of the honeycomb structure is taken as an end-side projection plane, and the honeycomb structure from the central axis direction of the honeycomb structure to the end-side projection plane Assuming that the hole is projected,
In all the holes projected onto the end face side projection plane, the angle between the central axis of one of the holes and the central axis of the other holes is 45 ° or the end face projection The angle between the central axis of one of the holes and the central axis of the other hole is 90 ° in all the holes projected onto the surface. Honeycomb structure. Two or more holes are formed,
A plane orthogonal to the central axis of the honeycomb structure and facing the inflow end face of the honeycomb structure is taken as an end-side projection plane, and the honeycomb structure from the central axis direction of the honeycomb structure to the end-side projection plane Assuming that the hole is projected,
The honeycomb structure according to any one of claims 1 to 3, wherein central axes of all the holes projected on the end surface side projection plane are parallel to each other. Two or more of the holes are formed, and the honeycomb structure portion has a cylindrical shape.
In the outflow end face of the honeycomb structure portion, a direction orthogonal to the thickness direction of the partition wall is taken as an X axis, a direction orthogonal to the X axis is taken as a Y axis, and a central axis of the honeycomb structure portion is taken as a Z axis Assuming that the coordinate axis of the honeycomb structure is L, the length of the honeycomb structure in the central axis direction is L, the radius at the outflow end face of the honeycomb structure is R, and a plane orthogonal to the Y axis is a side projection surface When it is assumed that the opening of the hole of the honeycomb structure body is projected from the direction of the Y axis to the side surface side projection surface,
The centers of the openings of all the holes projected onto the side projection surface are formed between L / 2 and 3L / 4 in the Z-axis direction, and -3R / 4 to + 3R in the X-axis direction. The honeycomb structure according to any one of claims 1 to 5, which is formed between 4/4.   The honeycomb structure according to any one of claims 1 to 6, wherein the opening of the hole is closed. The opening of the hole is closed with a blocking material;
The honeycomb structure according to any one of claims 1 to 7, further comprising an outer peripheral wall disposed so as to cover a side surface of the honeycomb structure portion and a surface of the closing material closing the opening of the hole.

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