JP2013202590A - Honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure in which excellent collection efficiency and the increase of pressure loss being controlled are exerted good in a balance, and particulate matters are prevented from depositing excessively.SOLUTION: A honeycomb structure 100 is provided witt a first honeycomb structure portion 11 having a porous partition 5 for compartmentally forming a plurality of cells 4 composed of a flow passage of a fluid by passing though from the first supply end surface 11a to the first discharge end surface and a second honeycomb structure portion 21 having a porous partition 15 for compartmentally forming a plurality of cells 14 composed of a flow passage of a fluid disposed in the downstream than this first honeycomb structure portion 11 and passing though from the second supply end surface to the second discharge end surface 21b. The second honeycomb structure portion 21 is joined to the first honeycomb structure portion 11 in the state so that the second supply end surface may be opposed to the first discharge end surface, and the porous partition 15 of the second honeycomb structure portion 21 is disposed so as to block the 15 to 40% of the opening of the cell 4 in the first honeycomb structure portion 11.

Description

  The present invention relates to a honeycomb structure. More specifically, the present invention relates to a honeycomb structure that exhibits good collection efficiency and suppresses an increase in pressure loss in a well-balanced manner, and prevents excessive accumulation of particulate matter such as ash and soot. .

  Conventionally, a honeycomb structure is used as a collection filter for removing particulate matter in exhaust gas discharged from an engine or the like. As this honeycomb structure, a wall flow type honeycomb structure, a straight flow type honeycomb structure, and the like are known. Among these, the wall flow type honeycomb structure is one in which both ends of the opening of the cell through which the exhaust gas flows are alternately plugged in a checkered pattern. This wall flow type honeycomb structure suppresses discharge by filtering exhaust gas through the pores of the cell partition walls and collecting particulate matter in the cell partition walls (see, for example, Patent Documents 1 and 2). .

  Such a wall flow type honeycomb structure has a larger pressure loss than a straight flow type honeycomb structure. Therefore, the plugging pattern is changed according to the case where the amount of particulate matter in the exhaust gas is small as in a gasoline engine or when exhaust gas purification efficiency is not strictly required. For example, a honeycomb structure in which only an opening on one end side of a cell is plugged has been reported (see, for example, Patent Document 3).

JP 2009-195805 A JP-A-5-163930 Japanese Patent No. 39442086

  However, the honeycomb structures described in Patent Documents 1 and 2 require time and effort for plugging the opening of the cell. In addition, the honeycomb structures described in Patent Documents 1 and 2 have good collection efficiency of particulate matter in exhaust gas, but have large pressure loss. Since there are cells whose openings are completely plugged, ash and soot are likely to accumulate. Therefore, there is a problem that ash and soot accumulate excessively when used in an automobile or the like that is not equipped with a regeneration control device, or when fuel that easily generates ash is used.

  The present invention has been made in view of such problems of the prior art. The problem is that “having good collection efficiency” and “suppressing the increase in pressure loss” are well-balanced, and particulate matter such as ash and soot may accumulate excessively. An prevented honeycomb structure is provided.

  According to the present invention, the following honeycomb structure is provided.

[1] A first honeycomb structure section having a porous partition wall that defines a plurality of cells penetrating from a first supply end face as one end face to a first discharge end face as the other end face and serving as a fluid flow path; And a porous material disposed downstream from the first honeycomb structure portion and defining a plurality of cells penetrating from the second supply end surface, which is one end surface, to the second discharge end surface, which is the other end surface, and serving as fluid flow paths A second honeycomb structure part having a partition wall, wherein the second supply end face of the second honeycomb structure part faces the first discharge end face of the first honeycomb structure part. So that the partition wall of the second honeycomb structure portion covers 15 to 40% of the opening of the cell in the first honeycomb structure portion. Arranged Honeycomb structure.

[2] The second honeycomb structure portion is disposed in a state of being rotated in a range of more than 0 ° and less than 90 ° around the central axis of the second honeycomb structure portion with respect to the first honeycomb structure portion. The honeycomb structure according to [1].

[3] The honeycomb structure according to [1] or [2], wherein the partition walls of the second honeycomb structure part are thicker than the partition walls of the first honeycomb structure part.

[4] The honeycomb structure according to any one of [1] to [3], wherein a cell density of the second honeycomb structure part is different from a cell density of the first honeycomb structure part.

[5] In the second honeycomb structure portion, the shape of the cell of the second honeycomb structure portion in a cross section perpendicular to the cell extending direction of the second honeycomb structure portion is the cell of the first honeycomb structure portion. The honeycomb structure according to any one of [1] to [4], which is different from a shape of the cell of the first honeycomb structure portion in a cross section perpendicular to the extending direction of the first honeycomb structure.

  The honeycomb structure of the present invention includes a first honeycomb structure portion and a second honeycomb structure portion. The second honeycomb structure portion is joined to the first honeycomb structure portion in a state where the second supply end surface of the second honeycomb structure portion is disposed so as to face the first discharge end surface of the first honeycomb structure portion. . The partition walls of the second honeycomb structure portion are arranged so as to block 15 to 40% of the cell openings in the first honeycomb structure portion. Therefore, a part of the particulate matter in the exhaust gas that has passed through the cells of the first honeycomb structure part is deposited on the end face of the second honeycomb structure part. That is, part of the particulate matter (ash and soot) in the exhaust gas that has passed through the cells of the first honeycomb structure part is collected by the second honeycomb structure part. Therefore, the collection efficiency of the particulate matter in the exhaust gas is improved as compared with the conventional straight flow honeycomb structure. The honeycomb structure of the present invention is “a straight flow type honeycomb structure in which the partition walls of the second honeycomb structure portion are arranged so as to block 15 to 40% of the cell openings in the first honeycomb structure portion. Is. That is, the cells in the first honeycomb structure part are appropriately opened. Therefore, the honeycomb structure of the present invention has a smaller pressure loss than the wall flow type honeycomb structure. From the above, the honeycomb structure of the present invention exhibits a good balance between “having good collection efficiency” and “suppressing an increase in pressure loss”.

  In the honeycomb structure of the present invention, the partition walls of the second honeycomb structure part are arranged so as to block 15 to 40% of the cell openings in the first honeycomb structure part. That is, as described above, the cells in the first honeycomb structure portion are appropriately opened. Therefore, the particulate matter deposited on the end face of the second honeycomb structure portion of the honeycomb structure of the present invention is swept away by the exhaust gas during use or easily burned by regeneration. As a result, the honeycomb structure of the present invention is prevented from excessively depositing particulate matter such as ash and soot.

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. It is sectional drawing which shows typically the cross section parallel to the cell extending direction of one embodiment of the honeycomb structure of the present invention. It is sectional drawing which expands and schematically shows a part of FIG. [Fig. 4] Fig. 4 is an explanatory view schematically showing a relationship between a discharge end face of a first honeycomb structure portion and a supply end face of a second honeycomb structure portion of an embodiment of the honeycomb structure of the present invention. FIG. 6 is an explanatory view schematically showing the relationship between the discharge end face of the first honeycomb structure portion and the supply end face of the second honeycomb structure portion of another embodiment of the honeycomb structure of the present invention. FIG. 6 is an explanatory view schematically showing a relationship between a discharge end face of a first honeycomb structure portion and a supply end face of a second honeycomb structure portion according to still another embodiment of the honeycomb structure of the present invention. FIG. 6 is an explanatory view schematically showing a relationship between a discharge end face of a first honeycomb structure portion and a supply end face of a second honeycomb structure portion according to still another embodiment of the honeycomb structure of the present invention.

  Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments, and appropriate modifications and improvements are added to the following embodiments on the basis of 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 also falls within the scope of the invention.

[1] Honeycomb structure:
One embodiment of the honeycomb structure of the present invention includes a first honeycomb structure part 11 and a second honeycomb structure disposed downstream of the first honeycomb structure part 11 as in the honeycomb structure 100 shown in FIGS. And a honeycomb structure portion 21. The first honeycomb structure section 11 partitions and forms a plurality of cells 4 that penetrate from the first supply end face 11a, which is one end face, to the first discharge end face 11b (see FIG. 3), which is the other end face, and serve as fluid flow paths. The porous partition wall 5 is provided. The second honeycomb structure portion 21 defines a plurality of cells 14 that penetrate from the second supply end surface 21a (see FIG. 3), which is one end surface, to the second discharge end surface 21b, which is the other end surface, and serve as fluid flow paths. A porous partition wall 15 is provided. As shown in FIGS. 2 and 3, the second honeycomb structure portion 21 is disposed so that the second supply end surface 21 a of the second honeycomb structure portion 21 faces the first discharge end surface 11 b of the first honeycomb structure portion 11. In this state, the first honeycomb structure portion 11 is joined. That is, the first honeycomb structure portion 11 and the second honeycomb structure portion 21 are arranged in series. “Arranged in series” means that the end faces of adjacent honeycomb structure portions are arranged to face each other. The honeycomb structure 100 is disposed so that the partition walls 15 of the second honeycomb structure portion 21 cover 15 to 40% of the openings of the cells 4 in the first honeycomb structure portion 11. Moreover, the 1st honeycomb structure part 11 and the 2nd honeycomb structure part 21 have the outer peripheral walls 7 and 17 arrange | positioned on the outer periphery. Note that the honeycomb structure of the present invention does not necessarily have the outer peripheral walls 7 and 17.

  The honeycomb structure 100 includes the first honeycomb structure portion 11 and the second honeycomb structure portion 21 described above. The second honeycomb structure portion 21 is arranged in a state where the second supply end surface 21a of the second honeycomb structure portion 21 is disposed so as to face the first discharge end surface 11b of the first honeycomb structure portion 11. 11 is joined. The honeycomb structure 100 is disposed so that the partition walls 15 of the second honeycomb structure portion 21 cover 15 to 40% of the openings of the cells 4 in the first honeycomb structure portion 11. Therefore, as shown in FIG. 3, a part of the particulate matter 30 in the exhaust gas G that has passed through the cells 4 of the first honeycomb structure 11 is deposited on the second supply end face 21 a of the second honeycomb structure 21. That is, a part of the particulate matter 30 in the exhaust gas G that has passed through the cells 4 of the first honeycomb structure 11 is collected by the second honeycomb structure 21. Note that the particulate matter 30 may enter and collect in the pores in the partition walls of the second honeycomb structure portion 21. Examples of the particulate matter 30 include ash and soot. Therefore, the collection efficiency of the particulate matter in the exhaust gas is improved as compared with the conventional straight flow honeycomb structure.

  Further, the honeycomb structure 100 is a straight flow type in which “the partition walls 15 of the second honeycomb structure portion 21 are arranged so as to cover 15 to 40% of the openings of the cells 4 in the first honeycomb structure portion 11”. It is a honeycomb structure. That is, the cells 4 in the first honeycomb structure portion 11 are appropriately opened. Therefore, the honeycomb structure 100 has a smaller pressure loss than the wall flow type honeycomb structure. From the above, the honeycomb structure 100 exhibits a good balance between “having good collection efficiency” and “suppressing an increase in pressure loss”.

  In addition, as described above, in the honeycomb structure 100, the cells 4 in the first honeycomb structure portion 11 are appropriately opened. Therefore, the particulate matter 30 deposited on the second supply end surface 21a of the second honeycomb structure portion 21 of the honeycomb structure 100 is swept away by the exhaust gas G during use or easily burned by regeneration. As a result, the honeycomb structure 100 is difficult to deposit excessive particulate matter 30 such as ash and soot.

  Such a honeycomb structure 100 can be used for an exhaust gas purification filter for emerging countries. This is because the emission regulations in emerging countries are loose, so high collection efficiency is not required. It can also be used as a retrofit filter. This is because the retrofit filter is not equipped with a regeneration control device and is required to suppress excessive accumulation of soot.

  FIG. 1 is a perspective view schematically showing one 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 of one embodiment of the honeycomb structure of the present invention. FIG. 3 is a cross-sectional view schematically showing a part of FIG. 2 in an enlarged manner.

  “Arranged so as to close” means that the flow of a part of the exhaust gas discharged from the cells 4 of the first honeycomb structure 11 is blocked by the partition walls 15 of the second honeycomb structure 21. This means that the partition walls 15 are arranged. That is, it means that a part of the flow path composed of the cells 4 of the first honeycomb structure portion 11 is blocked by the partition walls 15 of the second honeycomb structure portion 21.

  As described above, the honeycomb structure 100 is arranged such that the partition walls 15 of the second honeycomb structure portion 21 cover 15 to 40% of the openings of the cells 4 in the first honeycomb structure portion 11. That is, in the honeycomb structure 100, the blocking area ratio of the opening of the cell 4 in the first honeycomb structure 11 is 15 to 40%. In other words, the opening portions of the cells 4 in the first honeycomb structure portion 11 are opened at a ratio of 60 to 85%. The blocking area ratio is preferably 18 to 37%, more preferably 20 to 35%, and particularly preferably 25 to 30%. When the blocking area ratio is less than 15%, the area of the end face of the second honeycomb structure portion 21 that can collect soot is small, and thus the collection efficiency is lowered. If it exceeds 40%, the number of cells in which clogging occurs due to the accumulation of soot increases, so that the pressure loss increases.

Here, the cut-off area ratio covers “the opening of the cell 4 in the partition wall 15 of the second honeycomb structure 21” with respect to “the total area of the opening of the cell 4 in the first honeycomb structure 11”. The ratio (%) of the “total area of the parts”. Specifically, it is a value calculated as follows. Here, a plane orthogonal to the extending direction of the cells 4 of the honeycomb structure 100 is defined as a projection plane. First, the sum of the areas of the cell openings in a plurality of arbitrary visual fields in the end face of the first honeycomb structure 11 is calculated. Thereafter, the honeycomb structure 100 is disposed with respect to the projection plane so that one end face of the honeycomb structure 100 (second discharge end face 21b of the second honeycomb structure portion 21) faces the projection plane. Thereafter, the honeycomb structure is projected onto the projection plane from the direction in which the cells 4 of the honeycomb structure 100 extend, and a projection view as shown in the explanatory view of FIG. 4 is obtained. A portion corresponding to the “plural arbitrary fields of view” in the obtained projection view is subjected to image analysis to be divided into an opening portion and a partition wall portion. Thereafter, the cut-off area ratio is calculated by the following formula. “A portion corresponding to“ a plurality of arbitrary fields of view ”” refers to a portion where “a plurality of arbitrary fields of view in the end face of the first honeycomb structure 11” is projected onto the projection plane.
Formula: (1- (total area of openings / (total area of openings of cells 4 in the first discharge end face 11b of the first honeycomb structure 11))) × 100

  The second honeycomb structure 21 may use the same honeycomb structure as the first honeycomb structure 11 or a different one as long as the blocking area ratio of the first honeycomb structure satisfies the above condition.

  “The same honeycomb structure part as the first honeycomb structure part 11” is a honeycomb structure part having the same physical properties as the first honeycomb structure part 11 except at least “the length in the cell extending direction”. That is, when a honeycomb fired body obtained by extruding the clay into a honeycomb shape to produce a honeycomb molded body and then drying and firing is cut perpendicularly to the cell extending direction to obtain a plurality of honeycomb structure parts. These honeycomb structures can be referred to as “same” honeycomb structures.

  When the second honeycomb structure portion 21 is made of the same honeycomb structure portion as the first honeycomb structure portion 11, the following can be performed to satisfy the range of the blocking area ratio. That is, as shown in FIG. 4, the second honeycomb structure portion 21 is rotated with respect to the first honeycomb structure portion 11 in the range of more than 0 ° and less than 90 ° around the central axis of the second honeycomb structure portion 21. By arranging in a state where it is in a closed state, the range of the blocking area ratio can be satisfied. That is, the honeycomb structure of the present invention rotates the second honeycomb structure portion 21 with respect to the first honeycomb structure portion 11 in the range of more than 0 ° and less than 90 ° around the central axis of the second honeycomb structure portion 21. It may satisfy the above-mentioned interception area rate by arranging in the state where it was done. In such a honeycomb structure, since the first honeycomb structure portion 11 and the second honeycomb structure portion 21 have the same heat capacity, for example, when a thermal stress occurs during regeneration, the first honeycomb structure portion 11 and the second honeycomb structure portion 21 Cracks due to the difference in expansion of the second honeycomb structure 21 are unlikely to occur. FIG. 4 is an explanatory view schematically showing the relationship between the discharge end face of the first honeycomb structure portion and the supply end face of the second honeycomb structure portion of one embodiment of the honeycomb structure of the present invention.

  “To the first honeycomb structure portion 11” means “based on the first honeycomb structure portion 11”. That is, if the first honeycomb structure portion 11 is rotated in the same direction by the same angle as the rotation angle of the second honeycomb structure portion 21 around the central axis, the first honeycomb structure portion 11 and the second honeycomb structure portion 21 are rotated. Means the same posture. It means that the blocking area ratio of the opening of the cell 4 in the first honeycomb structure 11 is 0%.

  Further, as shown in FIG. 5, the honeycomb structure of the present invention satisfies the above-described blocking area ratio by making the partition walls 15 of the second honeycomb structure portion 21 thicker than the partition walls 5 of the first honeycomb structure portion 11. It may be. In particular, as shown in FIG. 5, when the partition walls 15 of the second honeycomb structure portion 21 are the same as the partition walls obtained by uniformly thickening the partition walls 5 of the first honeycomb structure portion 11, the cell 14 is the cell 4. Narrows uniformly. Therefore, the flow velocity of the exhaust gas flowing through the cells 4 and 14 can be made uniform, and soot can be prevented from being deposited unevenly. As a result, an increase in pressure loss can be prevented. FIG. 5 is an explanatory view schematically showing the relationship between the discharge end face of the first honeycomb structure portion and the supply end face of the second honeycomb structure portion of another embodiment of the honeycomb structure of the present invention. 5 to 7 show an example in which a honeycomb structure portion different from the first honeycomb structure portion 11 is used as the second honeycomb structure portion 21.

  Further, as shown in FIG. 6, the honeycomb structure of the present invention satisfies the above-described blocking area ratio by making the cell density of the second honeycomb structure portion 21 different from the cell density of the first honeycomb structure portion 11. There may be. In particular, as shown in FIG. 6, when the cells 14 of the second honeycomb structure portion 21 are the same as the cells formed by equally dividing the cells 4 of the first honeycomb structure portion 11 into a plurality of cells, , The cell 4 is uniformly narrowed. Therefore, the flow velocity of the exhaust gas flowing through the cells 4 and 14 can be made uniform, and soot can be prevented from being deposited unevenly. As a result, an increase in pressure loss can be prevented. FIG. 6 is an explanatory view schematically showing the relationship between the discharge end face of the first honeycomb structure portion and the supply end face of the second honeycomb structure portion of another embodiment of the honeycomb structure of the present invention.

  Furthermore, as shown in FIG. 7, the honeycomb structure of the present invention has the above-described blocking area ratio by making the shape of the cells 14 of the second honeycomb structure portion 21 different from the shape of the cells 4 of the first honeycomb structure portion 11. It may satisfy. The shape of the cells 4 and 14 is the shape of the cell in a cross section perpendicular to the extending direction of the cells 4 and 14.

  In addition, in order to satisfy | fill the said interruption | blocking area ratio, you may combine the method mentioned above.

  The physical properties (cell density, partition wall thickness, etc.) of the honeycomb structure part (first honeycomb structure part, second honeycomb structure part) will be described below. Note that the first honeycomb structure portion and the second honeycomb structure portion may have the same or different physical property values as long as the blocking area ratio is satisfied.

Cell density of the honeycomb structure section is preferably 16 to 93 pieces / cm ^2, further preferably from 31 to 78 pieces / cm ^2, and particularly preferably 47 to 62 pieces / cm ^2. When the cell density is in the above range, the pressure loss does not increase excessively, and the collection efficiency becomes good. That is, the function of “having good collection efficiency” and the function of “suppressing an increase in pressure loss” are exhibited in a well-balanced manner. If the cell density of the honeycomb structure portion is less than 16 cells / cm ² , the area of the end face of the second honeycomb structure portion that can collect soot may be small, so that sufficient collection efficiency may not be ensured. . If it exceeds 93 / cm ² , the flow path through which the exhaust gas can pass is narrow, so clogging of the soot may occur and pressure loss may increase. The cell density is the number of cells per unit area in a cross section perpendicular to the cell extending direction.

  The thickness of the partition walls of the honeycomb structure portion is preferably 0.08 to 0.51 mm, more preferably 0.10 to 0.38 mm, and particularly preferably 0.13 to 0.25 mm. . When the thickness of the partition wall is in the above range, the collection efficiency is improved without excessively increasing the pressure loss. That is, the function of “having good collection efficiency” and the function of “suppressing an increase in pressure loss” are exhibited in a well-balanced manner. If the partition wall thickness is less than 0.08 mm, the area of the end face of the second honeycomb structure part capable of collecting soot may be small, so that sufficient collection efficiency may not be ensured. If it exceeds 0.51 mm, the flow path through which the exhaust gas can pass is narrow, so clogging of the soot may occur and pressure loss may increase. The thickness of the partition wall is a value measured by a method of observing a cross section parallel to the central axis with a microscope.

  Examples of the shape of the cells of the honeycomb structure part include a polygon such as a quadrangle, a triangle, a hexagon, and an octagon, a circle, and an ellipse. The cell shape is preferably quadrangular in a cross section perpendicular to the cell extending direction.

  The porosity of the partition walls of the honeycomb structure portion is preferably 20 to 70%, more preferably 25 to 65%, and particularly preferably 30 to 60%. When the porosity of the partition walls is within the above range, there is an advantage that a honeycomb structure having sufficient strength while maintaining the function of collecting soot can be obtained. When the porosity of the partition walls is less than 20%, the exhaust gas hardly passes through the partition walls, so that soot is difficult to accumulate, and sufficient collection efficiency may not be obtained. If it exceeds 70%, sufficient strength cannot be obtained for the partition walls, and the partition walls may be damaged by a force such as thermal stress generated during the regeneration. The porosity of the partition wall is a value measured with a mercury porosimeter.

  The aperture ratio of the cells in the honeycomb structure part is preferably 55 to 85%, more preferably 60 to 80%, and particularly preferably 65 to 75%. When the aperture ratio of the cell is in the above range, the collection efficiency is improved without excessively increasing the pressure loss. That is, the function of “having good collection efficiency” and the function of “suppressing an increase in pressure loss” are exhibited in a well-balanced manner. If the open area ratio of the cell is less than 55%, clogging occurs due to soot, which may increase pressure loss. If it exceeds 85%, the area of the end face of the second honeycomb structure part on which soot accumulates becomes small, and there is a possibility that sufficient collection efficiency cannot be obtained. The cell aperture ratio is the cell aperture ratio at each of the one end face and the other end face of the honeycomb structure portion. The cell aperture ratio at one end face and the cell aperture ratio at one end face may be the same or different.

  The outer shape of the honeycomb structure part is preferably, for example, a columnar shape, an elliptical columnar shape, a quadrangular columnar shape, a pentagonal columnar shape, a hexagonal columnar shape, and more preferably a cylindrical shape. Moreover, as for the magnitude | size of a honeycomb structure part, it is preferable that the length in the cell extending direction is 50-450 mm, for example. Moreover, when the external shape of a honeycomb structure part is cylindrical shape, a diameter can be 100-400 mm.

  The partition walls and the outer peripheral wall of the honeycomb structure part are preferably composed mainly of ceramic. As a material of a partition and an outer peripheral wall, it is preferable that it is at least 1 sort (s) selected from the following groups, for example. That is, at least one selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. It is preferable. Among these, cordierite is preferable. This is because cordierite has a small thermal expansion coefficient and can provide a honeycomb structure excellent in thermal shock resistance. The material of the partition wall and the outer peripheral wall is preferably the same. In addition, the material of a partition and an outer peripheral wall may differ. “Ceramic is the main component” means that the ceramic is contained in an amount of 90% by mass or more.

[2] Manufacturing method of honeycomb structure:
Next, a method for manufacturing the honeycomb structure 100 shown in FIG. 1 will be described.

  First, a molding material containing a ceramic material is kneaded to obtain a clay. The forming raw material is preferably a ceramic raw material added with a dispersion medium and an additive. Examples of the additive include an organic binder, a pore former, and a surfactant. Examples of the dispersion medium include water.

  The ceramic raw material is selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite forming raw material, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. It is preferable that there is at least one. Among these, a cordierite-forming raw material having a small thermal expansion coefficient and excellent thermal shock resistance is preferable.

  Examples of the organic binder include methyl cellulose, hydroxypropoxyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, it is preferable to use methyl cellulose and hydroxypropoxyl cellulose in combination. The content of the organic binder is preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  The pore former is not particularly limited as long as it becomes pores after firing. Examples of the pore former include starch, foamed resin, water absorbent resin, silica gel and the like. The pore former content is preferably 5 to 15 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used alone. Moreover, you may use combining 2 or more types. It is preferable that content of surfactant is 0.1-2 mass parts with respect to 100 mass parts of ceramic raw materials.

  It is preferable that content of a dispersion medium is 10-30 mass parts with respect to 100 mass parts of ceramic raw materials.

  By adjusting the particle size and blending amount of the ceramic raw material (aggregate particles) used and the particle size and blending amount of the pore former to be added, a porous substrate having a desired porosity and average pore size is obtained. Can do.

  There is no particular limitation on the method of kneading the forming raw material to form the clay. For example, a method using a kneader, a vacuum kneader or the like can be mentioned.

  Next, a honeycomb formed body is manufactured by extrusion molding into a honeycomb shape. Extrusion molding can be performed using a die that can have a desired cell shape, partition wall thickness, and cell density. As the material of the die, a cemented carbide which does not easily wear is preferable.

  Next, the manufactured honeycomb formed body is fired to obtain a honeycomb fired body. The firing temperature can be appropriately determined depending on the material of the honeycomb formed body. For example, when the material of the honeycomb formed body is cordierite, the firing temperature is preferably 1380 to 1450 ° C, and more preferably 1400 to 1440 ° C. The firing time is preferably about 3 to 10 hours.

  The honeycomb formed body may be dried before firing. The drying method is not particularly limited. For example, hot air drying, microwave drying, dielectric drying, vacuum drying, vacuum drying, freeze drying and the like can be mentioned. Among these, it is preferable to perform dielectric drying, microwave drying, or hot air drying alone or in combination. The drying conditions are preferably a drying temperature of 30 to 150 ° C. and a drying time of 1 minute to 2 hours.

  Next, the obtained honeycomb fired body is cut in a direction perpendicular to the cell extending direction to obtain two “cut honeycomb fired bodies”.

  Next, one “cut honeycomb fired body” of the two obtained “cut honeycomb fired bodies” is centered on the central axis of one “cut honeycomb fired body” with respect to the other “cut honeycomb fired body”. Rotate at a predetermined angle. Thereafter, the two “cut honeycomb fired bodies” are joined to each other in this state. In this manner, a honeycomb structure 100 having the first honeycomb structure portion 11 and the second honeycomb structure portion 21 arranged in series with the first honeycomb structure portion 11 as shown in FIG. 1 can be manufactured. it can.

  Next, the honeycomb structure in which the first discharge end face 11b (see FIG. 3) of the first honeycomb structure portion 11 and the second supply end face 21a (see FIG. 3) of the second honeycomb structure portion 21 have a relationship as shown in FIG. A method for manufacturing the body will be described.

  First, a honeycomb fired body (first honeycomb fired body) is manufactured in the same manner as the method for manufacturing the honeycomb structure 100 shown in FIG. Next, a honeycomb fired body (second honeycomb fired body) is produced that differs from the honeycomb fired body in at least one selected from the group consisting of cell density, partition wall thickness, and cell shape. Next, the first honeycomb fired body and the second honeycomb fired body are arranged in series, and then they are joined to each other. In this way, a honeycomb structure having the first honeycomb structure 11 and the second honeycomb structure 21 arranged in series with the first honeycomb structure 11 can be manufactured.

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

Example 1
As a cordierite forming raw material, alumina, aluminum hydroxide, kaolin, talc, and silica were used. To 100 parts by mass of the cordierite forming raw material, 10 parts by mass of a pore former, 20 parts by mass of a dispersion medium, 1 part by mass of an organic binder, and 0.5 parts by mass of a dispersant are added, mixed, and kneaded. A clay was prepared. Water was used as the dispersion medium, and coke having an average particle size of 10 to 50 μm was used as the pore former. Hydroxypropyl methylcellulose was used as the organic binder, and ethylene glycol was used as the dispersant.

  Next, the kneaded material was extruded using a predetermined mold to produce a honeycomb formed body having partition walls that partitioned and formed a plurality of cells penetrating from one end face to the other end face. In the honeycomb formed body, the cell shape in a cross section orthogonal to the cell extending direction was a quadrangle, and the overall shape was a columnar shape. Next, the produced honeycomb formed body was dried with a microwave dryer, and further dried with a hot air dryer to obtain a dried honeycomb formed body (honeycomb dried body). Thereafter, both ends of the dried honeycomb body were cut and adjusted to a predetermined size.

  Next, the dried honeycomb body was dried with a hot air dryer. Thereafter, the honeycomb fired body was obtained by firing at 1410 to 1440 ° C. for 5 hours. This honeycomb fired body was used as the first honeycomb structure.

The obtained honeycomb fired body had a diameter of 266.7 mm and a length in the central axis direction of 101.6 mm. The cell density of the honeycomb fired body was 47 cells / cm ² . The partition wall thickness was 0.20 mm. The porosity of the partition walls was 35%. The average pore diameter of the partition walls was 4 μm. The cell shape in the cross section orthogonal to the cell extending direction of the honeycomb fired body was a quadrangle. The open area ratio of the cell was 72%. The porosity and average pore diameter of the partition walls were measured with a mercury porosimeter, respectively. The results are shown in Table 1.

Next, another honeycomb fired body was produced in the same manner as described above. This honeycomb fired body had a diameter of 266.7 mm and a length in the central axis direction of 101.6 mm. The cell density of the honeycomb fired body was 47 cells / cm ² . The partition wall thickness was 0.30 mm. The porosity of the partition walls was 35%. The average pore diameter of the partition walls was 4 μm. The cell shape in the cross section orthogonal to the cell extending direction of the honeycomb fired body was a quadrangle. The cell aperture ratio was 61%. This honeycomb fired body was used as the second honeycomb structure part.

  Next, the first honeycomb structure portion and the second honeycomb structure portion were arranged in series and joined to each other. Thus, a honeycomb structure as shown in FIG. 5 was produced.

  The obtained honeycomb structure was arranged such that the partition walls of the second honeycomb structure portion closed 15% of the cell openings in the first honeycomb structure portion. That is, the blocking area ratio was 15%. The results are shown in Table 2. The area ratio (blocking area ratio (blocking area ratio)) of the “cell openings in the first honeycomb structure section” blocked by the partition walls of the second honeycomb structure section was measured as follows. .

[Blockage area ratio]:
A plane orthogonal to the cell extending direction of the honeycomb structure is defined as a projection plane. First, a digital camera is used to take a picture of the end face of the first honeycomb structure portion, and a plurality of arbitrary fields of view in the photograph are subjected to image processing. The total area of the cell openings in the “field of view” was calculated. Next, the honeycomb structure was arranged with respect to the projection plane so that one end face of the honeycomb structure (second discharge end face of the second honeycomb structure portion) and the projection plane face each other. Next, the honeycomb structure was projected onto the projection plane from the cell extending direction of the honeycomb structure to obtain a projection view as shown in the explanatory view of FIG. Next, an image analysis was performed on a portion corresponding to the “plural arbitrary fields of view” in the obtained projection view, and the image was divided into an opening portion and a partition wall portion. Thereafter, the cut-off area ratio was calculated by the following formula.
Formula: (1- (total area of openings / (total area of openings of cells 4 in the first discharge end face 11b of the first honeycomb structure 11))) × 100

  Next, each evaluation of [pressure loss] and [collection efficiency] was performed on the manufactured honeycomb structure. The evaluation method for each evaluation is shown below.

[Pressure loss]:
First, the manufactured honeycomb structure was stored in a storage can to obtain an exhaust gas purification system. Next, the exhaust gas at 250 ° C. was vented to the exhaust gas purification system using a 7L diesel engine. And the pressure loss in this case was measured. For the evaluation of the pressure loss, the pressure loss ratio was calculated based on the case where the blocking area ratio was 0% (Comparative Example 1). When the pressure loss ratio is 2.5 or less, “A (better)”, when the pressure loss ratio exceeds 2.5 and is 3.5 or less, “B (good)”, the pressure loss ratio The case where the value exceeds 3.5 is defined as “C (defect)”.

[Collection efficiency]:
First, an exhaust gas purification system was produced in the same manner as in the above evaluation of [pressure loss]. Next, the exhaust gas at 250 ° C. was vented to the exhaust gas purification system using a 7L diesel engine. Next, the mass of the particulate matter on the inlet side and the mass of the particulate matter on the outlet side of the exhaust gas purification system were measured. Thereafter, the collection efficiency was calculated by the formula: outlet side mass / inlet side mass × 100. The collection efficiency was evaluated based on the collection efficiency when the soot accumulation amount was 2 g / L. When the collection efficiency is 30% or more, “A (better)”, when the collection efficiency is 15% or more and less than 30%, “B (good)”, and when the collection efficiency is less than 15% Was designated as “C (defect)”.

  The honeycomb structure of the present example had a pressure loss evaluation of “A”. The evaluation of the collection efficiency was “B”. The results are shown in Table 2.

(Example 2)
A honeycomb structure was manufactured in the same manner as in Example 1 except that the conditions shown in Table 1 were satisfied. For this honeycomb structure, the ratio of the blocking area was measured, and each evaluation of [pressure loss] and [collection efficiency] was performed. The results are shown in Table 2.

(Example 3)
First, a honeycomb fired body was manufactured in the same manner as in Example 1 so that the “cut honeycomb fired body” after cutting satisfies the physical properties shown in Table 1. Next, the honeycomb fired bodies were cut so that the “cut honeycomb fired bodies” satisfy the lengths shown in Table 1 to obtain two “cut honeycomb fired bodies”.

  Next, one “cut honeycomb fired body” of the two obtained “cut honeycomb fired bodies” is centered on the central axis of one “cut honeycomb fired body” with respect to the other “cut honeycomb fired body”. Rotated 30 °. Thereafter, two “cut honeycomb fired bodies” were joined to each other in this state. Thus, a honeycomb structure having a first honeycomb structure and a second honeycomb structure arranged in series with the first honeycomb structure was manufactured.

  About the produced honeycomb structure, while measuring the ratio of the said blocking area, each [pressure loss] and [collection efficiency] were evaluated. The results are shown in Table 2.

(Comparative Example 1)
A honeycomb fired body was manufactured in the same manner as in Example 3 except that the conditions shown in Table 1 were satisfied. The honeycomb fired body was used as a honeycomb structure, and the above evaluations of [pressure loss] and [collection efficiency] were performed. The results are shown in Table 2.

(Examples 4, 5, 9, 12 and Comparative Examples 3 and 4)
Each honeycomb structure was manufactured in the same manner as in Example 3 except that a honeycomb fired body satisfying the conditions shown in Table 1 was manufactured and “one“ cut honeycomb fired body ”” was rotated at an angle shown in Table 2. Was made. Thereafter, “the ratio of the cut-off area” was measured for each manufactured honeycomb structure in the same manner as in Example 1, and the above-described evaluations (pressure loss and collection efficiency) were performed. The results are shown in Table 2.

(Examples 6-8, 10, 11, 13, 14, Comparative Examples 2 and 5)
Each honeycomb structure was produced in the same manner as in Example 1 except that the conditions shown in Tables 1 and 2 were satisfied. Thereafter, for each of the manufactured honeycomb structures, the ratio of the cut-off area was measured, and each of the above [pressure loss] and [collection efficiency] was evaluated. The results are shown in Table 2.

  As is clear from Table 2, it was confirmed that the honeycomb structures of Examples 1 to 14 were good in both the collection efficiency and pressure loss of the particulate matter in the exhaust gas. That is, the honeycomb structures of Examples 1 to 14 have a function of “having good collection efficiency” and a function of “inhibiting an increase in pressure loss” as compared with the honeycomb structures of Comparative Examples 1 to 5. It was confirmed that and were exhibited in a well-balanced manner. In addition, in the honeycomb structures of Examples 1 to 14, the “ratio of blocking area” is in the range of 15 to 40%. That is, the cells of the first honeycomb structure part are appropriately opened. Therefore, particulate substances such as ash and soot are difficult to stay in the honeycomb structure for a long time. As a result, it was confirmed that excessive accumulation of particulate matter such as ash and soot was prevented. That is, in the honeycomb structures of Examples 1 to 14, soot was deposited only about 20 to 40% with respect to the average collection efficiency of the conventional DPF.

  The honeycomb structure of the present invention can be suitably used for exhaust gas purification.

4, 14: cells, 5, 15: partition walls, 7, 17: outer peripheral wall, 11: first honeycomb structure part, 11a: first supply end face, 11b: first discharge end face, 21: second honeycomb structure part, 21a : Second supply end face, 21b: second discharge end face, 30: particulate matter, 100: honeycomb structure, G: exhaust gas.

Claims (5)

A first honeycomb structure portion having a porous partition wall that defines a plurality of cells that penetrate from a first supply end surface, which is one end surface, to a first discharge end surface, which is the other end surface, and serve as fluid flow paths; A porous partition wall disposed downstream of one honeycomb structure and penetrating from a second supply end surface, which is one end surface, to a second discharge end surface, which is the other end surface, and defines a plurality of cells serving as fluid flow paths. A second honeycomb structure having
The second honeycomb structure portion is arranged in the first honeycomb structure portion in a state where the second supply end surface of the second honeycomb structure portion is disposed so as to face the first discharge end surface of the first honeycomb structure portion. Are joined,
A honeycomb structure in which the partition walls of the second honeycomb structure portion are arranged so as to block 15 to 40% of the opening portions of the cells in the first honeycomb structure portion.   2. The second honeycomb structure portion is disposed in a state of being rotated in a range of more than 0 ° and less than 90 ° around the central axis of the second honeycomb structure portion with respect to the first honeycomb structure portion. The honeycomb structure according to 1.   The honeycomb structure according to claim 1 or 2, wherein the partition walls of the second honeycomb structure part are thicker than the partition walls of the first honeycomb structure part.   The honeycomb structure according to any one of claims 1 to 3, wherein a cell density of the second honeycomb structure portion is different from a cell density of the first honeycomb structure portion.   In the second honeycomb structure portion, the cell shape of the second honeycomb structure portion in a cross section perpendicular to the cell extension direction of the second honeycomb structure portion is the direction in which the cells of the first honeycomb structure portion extend. The honeycomb structure according to any one of claims 1 to 4, which is different from a shape of the cell of the first honeycomb structure portion in a cross section perpendicular to the vertical axis.

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