WO2009118809A1

WO2009118809A1 - Honeycomb structure

Info

Publication number: WO2009118809A1
Application number: PCT/JP2008/055456
Authority: WO
Inventors: 大野一茂; 尾久和丈; 石川茂治
Original assignee: イビデン株式会社
Priority date: 2008-03-24
Filing date: 2008-03-24
Publication date: 2009-10-01

Abstract

A honeycomb structure that at regeneration treatment, is free from any occurrence of unburnt residue of particulate matter or cracking. There is disclosed a honeycomb structure of circular or elliptic cylinder configuration consisting of a ceramic block having, bound via an adhesive layer, multiple columnar honeycomb fired bodies each having a multiplicity of cells laid parallelly in the longitudinal direction with a cell wall interposed therebetween. The multiple honeycomb fired bodies include a central honeycomb fired body positioned in the central part of the honeycomb structure and a peripheral honeycomb fired body constituting a portion of the outer peripheral side face of the ceramic block. The central honeycomb fired body is 900 to 2500 mm² in the area of section perpendicular to the above longitudinal direction. In the section of the ceramic block perpendicular to the above longitudinal direction, when a similar figure of 49% area with a center common to that of the section is drawn, portion of the peripheral honeycomb fired body lies without fail inside the similar figure.

Description

Honeycomb structure

The present invention relates to a honeycomb structure.

A recent problem is that particulate matter (hereinafter also simply referred to as particulates or PM) contained in exhaust gas discharged from internal combustion engines such as buses and trucks and construction machinery and the like causes harm to the environment and the human body. It has become.
In view of this, various honeycomb structures made of porous ceramics have been proposed as filters capable of collecting particulates in exhaust gas and purifying the exhaust gas.

As such a honeycomb structure, for example, a honeycomb structure manufactured by binding a plurality of square pillar-shaped honeycomb fired bodies through an adhesive layer and then cutting them into a predetermined shape has been proposed. (For example, refer to Patent Document 1).
In the cross section perpendicular to the longitudinal direction of the honeycomb structure, a honeycomb fired body having a quadrangular cross-sectional shape is located at the center, and a honeycomb fired body having a smaller cross-sectional area than the honeycomb fired body at the center is located at the outer periphery.
Further, as another honeycomb structure, a honeycomb fired body having a quadrangular cross-sectional shape is located in the center in a cross section perpendicular to the longitudinal direction, and the honeycomb fired body at the outer periphery is separated from the honeycomb fired body in the center portion. A honeycomb structure in which a honeycomb fired body having a large area is located has been proposed (see, for example, Patent Document 2).

WO01 / 23069 pamphlet WO04 / 96414 pamphlet

When the honeycomb structure is used as an exhaust gas purification filter, the high-temperature exhaust gas discharged from the internal combustion engine flows into the cells of the honeycomb structure. At this time, since a large amount of heat is applied to the honeycomb fired body located in the central portion, the temperature of the honeycomb fired body located in the central portion is likely to increase compared to the honeycomb fired body located in the outer peripheral portion.

In addition, in a honeycomb structure in which a plurality of honeycomb fired bodies are bundled via an adhesive layer, the thermal conductivity of the adhesive layer is usually inferior to that of the honeycomb fired body. Conduction is inhibited.
Therefore, in the honeycomb structure, the more the honeycomb fired body located on the outer peripheral portion separated from the adhesive layer is located on the outer side (outer peripheral side) of the honeycomb structure, the The temperature difference increases.
In the honeycomb structures disclosed in Patent Documents 1 and 2, a honeycomb fired body whose cross-sectional area is sufficiently smaller than that of the honeycomb fired body in the central portion is positioned on the outer periphery thereof. Is located on the outer side of the honeycomb structure (position far from the center) via the adhesive layer. The presence of such a honeycomb fired body becomes a factor that increases the temperature difference between the central portion and the outer peripheral portion described above.
If the temperature difference between the central portion and the outer peripheral portion of the honeycomb structure becomes large, when the honeycomb structure is subjected to a regeneration process for burning and removing the particulates, the unburned particulates on the outer peripheral portion of the honeycomb structure. Is likely to occur.

The present inventors have studied to reduce the temperature difference between the central portion and the outer peripheral portion, and completed the present invention. That is, the honeycomb structure according to claim 1
A columnar honeycomb fired body in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall is a cylindrical or elliptical columnar honeycomb structure comprising a plurality of ceramic blocks bound through an adhesive layer. ,
The plurality of honeycomb fired bodies includes a central honeycomb fired body positioned at the center of the honeycomb structure and an outer peripheral honeycomb fired body constituting a part of the outer peripheral side surface of the ceramic block.
The central honeycomb fired body has an area of a cross section perpendicular to the longitudinal direction of 900 to 2500 mm ² .
In a cross section perpendicular to the longitudinal direction of the ceramic block, when a similar shape having a concentric area of 49% is drawn in the cross section of the ceramic block, a part of the outer peripheral honeycomb fired body is always inside the similar shape. It is a honeycomb structure characterized by being located.

The honeycomb structure according to claim 1, wherein a plurality of honeycomb fired bodies are bundled together through an adhesive layer, and the plurality of honeycomb fired bodies include the central honeycomb fired body and the outer peripheral honeycomb fired body. It consists of.
In the honeycomb structure, when a cross-section perpendicular to the longitudinal direction of the ceramic block is concentric with the center of the cross section and a similar shape with an area of 49% is drawn, a part of the outer peripheral honeycomb fired body is It is configured to be positioned inside the similar shape.

In such a configuration, in the cross section perpendicular to the longitudinal direction of the honeycomb structure including the central honeycomb fired body and the peripheral honeycomb fired body, the outer peripheral honeycomb is located only outside the similar shape with the area of 49%. Since the fired body does not exist, temperature distribution hardly occurs at the center portion and the outer peripheral portion of the honeycomb structure, and unburned particulates hardly occur.
In the honeycomb structure, a large amount of heat is applied to the central portion thereof, so that the temperature of the central honeycomb fired body is likely to increase as compared to the peripheral honeycomb fired body. Accordingly, in the cross section of the ceramic block, if a part of each outer peripheral honeycomb fired body exists inside the similar shape having a concentric cross section and center and an area of 49%, heat is easily transmitted to the outer peripheral honeycomb fired body. As described above, it is difficult for the particulates to remain unburned.
On the other hand, when a part of each outer peripheral honeycomb fired body does not exist inside the similar shape (when each outer peripheral honeycomb fired body exists only outside the similar shape), Temperature distribution is likely to occur at the outer periphery, and particulate burnout is likely to occur.

In the honeycomb structure according to claim 1, the cross-sectional area of the cross section perpendicular to the longitudinal direction of the central honeycomb fired body is 900 to 2500 mm ² .
The reason why the cross-sectional area of the cross section perpendicular to the longitudinal direction of the central honeycomb fired body is in the above range is as follows.
That is, when the cross-sectional area of the cross section perpendicular to the longitudinal direction of the central honeycomb fired body is less than 900 mm ² , the adhesive layer increases, resulting in a temperature distribution in the honeycomb structure and cracks in the honeycomb fired body during the regeneration process. May occur.
In addition, if the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb fired body in the center is large, the proportion of the adhesive layer is relatively small, so that the temperature distribution is less likely to occur during the regeneration process. The effect of relieving the thermal stress carried by is insufficient, and in this case as well, cracks may occur in the honeycomb fired body. Therefore, the upper limit of the cross-sectional area of the cross section perpendicular to the longitudinal direction of the central honeycomb fired body is 2500 mm ² .
That is, by making the cross-sectional area of the cross section perpendicular to the longitudinal direction of the central honeycomb fired body within the above range, the generation of cracks in the honeycomb fired body during the regeneration process can be more reliably prevented.

In the present invention, the central honeycomb fired body refers to a honeycomb fired body that does not constitute the outer edge of the ceramic block in a cross section perpendicular to the longitudinal direction of the ceramic block, and the outer peripheral honeycomb fired body refers to the longitudinal length of the ceramic block. A honeycomb fired body constituting the outer edge of the ceramic block in a cross section perpendicular to the direction.

Further, in the present invention, in a cross section perpendicular to the longitudinal direction of the ceramic block, a similar shape having a concentric area of 49% and an area of 49% is the center of the ceramic block when the shape of the ceramic block is a cylindrical shape. If the diameter of the ceramic block is concentric with the center of the cross section perpendicular to the longitudinal direction and the diameter is 0.7 times the diameter of the cross section perpendicular to the longitudinal direction of the ceramic block (circular), and the shape of the ceramic block is an elliptic cylinder, The center is concentric with the center of the ceramic block, and each of the major axis and the minor axis is an ellipse that is 0.7 times the major axis and minor axis of the cross section (elliptical shape) perpendicular to the longitudinal direction of the ceramic block.

Hereinafter, in this specification, when a section of a honeycomb structure, a section of a ceramic block, a section of a honeycomb fired body, or a section of a honeycomb formed body is referred to, a section perpendicular to the longitudinal direction of the honeycomb structure, respectively. A cross section perpendicular to the longitudinal direction of the ceramic block, a cross section perpendicular to the longitudinal direction of the honeycomb fired body, or a cross section perpendicular to the longitudinal direction of the honeycomb formed body.
Further, in the present specification, when the cross-sectional area of the honeycomb structure, the cross-sectional area of the ceramic block, the cross-sectional area of the honeycomb fired body, or the cross-sectional area of the honeycomb formed body, Cross-sectional area perpendicular to the longitudinal direction of the ceramic block, cross-sectional area perpendicular to the longitudinal direction of the ceramic block, cross-sectional area perpendicular to the longitudinal direction of the honeycomb fired body, or cross-sectional area perpendicular to the longitudinal direction of the honeycomb molded body Point to.

As described above, the honeycomb fired body constituting the honeycomb structure of the present invention includes the central honeycomb fired body and the outer peripheral honeycomb fired body. However, in the following description, when it is not necessary to distinguish between the two, it is simply expressed as a honeycomb fired body.

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of a honeycomb structure of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view schematically showing the honeycomb structure of the first embodiment. FIG. 2A is a perspective view schematically showing the center-portion honeycomb fired body in the honeycomb structure of the first embodiment. FIG. 2B is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a perspective view schematically showing the outer peripheral honeycomb fired body in the honeycomb structure of the first embodiment.

In the honeycomb structure 100 shown in FIG. 1, a plurality of central honeycomb fired bodies 110 having a shape as shown in FIGS. 2A and 2B and a plurality of outer peripheral honeycomb fired bodies 120 having a shape as shown in FIG. The ceramic block 103 is formed by being bundled individually through the adhesive layer 101, and a coat layer 102 is formed on the outer periphery of the ceramic block 103.
The shape of the cross section of the central honeycomb fired body 110 is a square.
The cross-sectional shape of the outer peripheral honeycomb fired body 120 is surrounded by three

line segments

120a, 120b, and 120c and one arc 120d, and two corners (line lines) formed by two of the three line segments. The angle formed by the minute segment 120b and the line segment 120c and the angle formed by the line segment 120a and the line segment 120b) are 90 ° and 135 °, respectively.
The honeycomb fired

bodies

110 and 120 are made of a porous silicon carbide sintered body.

In the central honeycomb fired body 110 shown in FIGS. 2 (a) and 2 (b), a large number of cells 111 are arranged in parallel in the longitudinal direction (in the direction of arrow a in FIG. 2 (a)) with a cell wall 113 therebetween. One end of the cell 111 is sealed with a sealing material 112. Therefore, the exhaust gas G (see the arrow in FIG. 2B) that flows into the cell 111 with one end face opened must always pass through the cell wall 113 separating the cell 111 and then the other cell with the other end face open. 111 flows out.
Therefore, the cell wall 113 functions as a filter for collecting PM and the like.

Similarly to the central honeycomb fired body 110, the outer peripheral honeycomb fired body 120 shown in FIG. 3 has a large number of cells 121 arranged in parallel in the longitudinal direction across the cell wall 123. Is sealed with a sealing material 122. Therefore, the exhaust gas that has flowed into the cell 121 having one open end face always passes through the cell wall 123 separating the cells 121 and then flows out from the other cell 121 having the other end face open.
That is, the outer peripheral honeycomb fired body 120 has the same function as the central honeycomb fired body 110, although the outer shape is different from the central honeycomb fired body 110.

In the honeycomb structure 100, as shown in FIG. 1, four central honeycomb fired bodies 110 are located in the central part of the cross section of the honeycomb structure 100, and eight outer peripheral honeycomb fired bodies 120 are located around the central fired bodies. The honeycomb structure 100 (ceramic block 103) is bound via an adhesive layer 101 so that the cross section of the honeycomb structure 100 (ceramic block 103) is circular.

In the honeycomb structure 100, when a similar shape (circular shape) 105 having an area of 49% is concentric with the center of the cross section in the cross section of the ceramic block 103, a part of all the outer peripheral honeycomb fired bodies 120 is drawn. Is located inside the similar shape 105.
In this way, when a part of all the outer peripheral honeycomb fired bodies 120 are located inside the similar shape 105, the adhesive material layer is interposed at a position away from the center of the honeycomb structure 100 (ceramic block 103). Since there is no outer peripheral honeycomb fired body that exists in isolation, a temperature distribution is less likely to occur between the central portion and the outer peripheral portion of the honeycomb structure.

In the honeycomb structure 100, the cross-sectional area of the central honeycomb fired body 110 is 900 to 2500 mm ² .
By setting the cross-sectional area of the central honeycomb fired body 110 to such a size, it is possible to prevent the honeycomb structure 100 from being cracked when the honeycomb structure 100 is subjected to a regeneration process.

Next, a method for manufacturing the honeycomb structure of the present embodiment will be described.
(1) A forming step for producing a honeycomb formed body by extruding a wet mixture containing a ceramic powder and a binder is performed.
Specifically, first, a wet mixture for manufacturing a honeycomb formed body is prepared by mixing silicon carbide powder having different average particle diameters as ceramic powder, an organic binder, a liquid plasticizer, a lubricant, and water. .
Subsequently, the wet mixture is charged into an extruder. The wet mixture is put into an extruder and extruded to produce a honeycomb formed body having a predetermined shape.

Here, a honeycomb molded body having a square cross section, or a cross section surrounded by three line segments and one arc, two angles formed by two of the three line segments are 90 ° and 135 °, respectively. In order to produce a honeycomb molded body having a shape of 0 °, an extrusion mold corresponding to each shape is used.

(2) Next, the honeycomb formed body is cut into a predetermined length and dried using a microwave dryer, hot air dryer, dielectric dryer, vacuum dryer, vacuum dryer, freeze dryer, or the like. Then, a sealing step of filling a predetermined cell with a sealing material paste as a sealing material and sealing the cell is performed.
In addition, the conditions conventionally used when manufacturing a honeycomb fired body can be applied to the conditions of the cutting process, the drying process, and the sealing process.

(3) Next, a degreasing step of heating the organic matter in the honeycomb molded body in a degreasing furnace is performed, and the honeycomb fired body is transported to the firing furnace and the firing step is performed to produce a honeycomb fired body.
In addition, as conditions of a degreasing process and a baking process, the conditions conventionally used when manufacturing a honeycomb fired body are applicable.
Through the above steps, the central honeycomb fired body and the outer peripheral honeycomb fired body can be manufactured.

(4) Next, an adhesive paste layer is formed by applying an adhesive paste to the predetermined side surfaces of the center honeycomb fired body and the peripheral honeycomb fired body in which predetermined ends of each cell are sealed. Then, a step of laminating other honeycomb fired bodies sequentially on this adhesive paste layer is repeated to perform a binding step for producing a ceramic block in which a predetermined number of honeycomb fired bodies are bound.
Here, as the adhesive paste, for example, a paste made of an inorganic binder, an organic binder, and inorganic particles is used. The adhesive paste may further contain inorganic fibers and / or whiskers.

(5) Next, a coating layer forming step is performed in which a coating material paste is applied to the outer periphery of the cylindrical ceramic block, dried and solidified to form a coating layer.
Here, as the coating material paste, the same paste as the adhesive paste is used. In addition, you may use the paste of a different composition as a coating material paste.
Note that the coat layer is not necessarily provided, and may be provided as necessary.
Through the above steps, the honeycomb structure of the present embodiment can be manufactured.

Hereinafter, effects of the honeycomb structure of the present embodiment will be listed.
(1) In the honeycomb structure of the present embodiment, in the cross section of the ceramic block, when a similar shape having an area of 49% is concentric with the center of the cross section, a part of the outer peripheral honeycomb fired body is It is always located inside the similar shape. Therefore, in the cross section of the honeycomb structure, there is no outer peripheral honeycomb fired body located only outside the similar shape, and temperature distribution is unlikely to occur between the central portion and the outer peripheral portion of the honeycomb structure, so that the regeneration process is performed. It is difficult for particulates to remain unburned.

(2) In the honeycomb structure of the present embodiment, the cross-sectional area of the central honeycomb fired body is 900 to 2500 mm ² . Therefore, cracks do not occur in the honeycomb fired body when the regeneration process is performed.

(3) In the honeycomb fired body constituting the honeycomb structure of the present embodiment, one end of each cell is sealed with a sealing material. Therefore, the honeycomb structure of the present embodiment can be suitably used as a diesel particulate filter.

(4) In the honeycomb structure of the present embodiment, since the coat layer is formed on the outer peripheral side surface of the ceramic block, leakage of particulates from the outer peripheral side surface of the honeycomb structure can be prevented.

Example 1
Examples that more specifically disclose the first embodiment of the present invention will be described below. In addition, this invention is not limited only to these Examples.

(1) 52.8% by weight of silicon carbide coarse powder having an average particle size of 22 μm and 22.6% by weight of fine powder of silicon carbide having an average particle size of 0.5 μm are mixed, and the resulting mixture is mixed. 2.1% by weight of acrylic resin, 4.6% by weight of organic binder (methyl cellulose), 2.8% by weight of lubricant (Unilube manufactured by NOF Corporation), 1.3% by weight of glycerin, and 13.8% by weight of water Was added and kneaded to obtain a wet mixture, followed by a molding step of extrusion molding.
In this step, a raw honeycomb molded body having substantially the same shape as the center-portion honeycomb fired body 110 shown in FIGS. 2A and 2B and having no cell plugged, and FIG. Further, a raw honeycomb molded body having substantially the same shape as the outer peripheral honeycomb fired body 120 and having no cell sealing was produced.

(2) Next, the raw honeycomb molded body is dried using a microwave dryer to obtain a dried honeycomb molded body, and then a predetermined cell is filled with a paste having the same composition as the wet mixture, and again It dried using the dryer.

(3) A degreasing step of degreasing the dried honeycomb formed body at 400 ° C. was performed, and further a firing step was performed at 2200 ° C. for 3 hours under an atmospheric pressure of argon atmosphere.
As a result, the porosity was 45%, the average pore diameter was 15 μm, the size was 34.5 mm × 34.5 mm × 150 mm, the number of cells (cell density) was 300 / inch ² , and the cell wall thickness was 0.1. A central honeycomb fired body 110 made of 25 mm (10 mil) porous silicon carbide sintered body;
The porosity, the average pore diameter, the number of cells (cell density), and the cell wall thickness are the same as those of the central honeycomb fired body 110, and the cross section is surrounded by three line segments and one arc. The outer periphery of the shape (line segment 120a = 20.8 mm, line segment 120b = 35.0 mm, line segment 120c = 35.7 mm) in which two angles formed by two line segments of the segment are 90 ° and 135 °, respectively. Part honeycomb fired body 120 was manufactured.

(4) Adhesive paste is applied to predetermined side surfaces of the central honeycomb fired body 110 and the peripheral honeycomb fired body 120, and four central honeycomb fired bodies 110 and the outer peripheral part are interposed through the adhesive paste. Four honeycomb fired bodies 120 are bonded so that the arrangement shown in FIG. 4 is obtained, and further, the adhesive paste is solidified at 180 ° C. for 20 minutes, so that the thickness of the adhesive layer is 1 mm. The ceramic block 103 was produced.
Here, the adhesive paste is composed of 30.0% by weight of silicon carbide particles having an average particle diameter of 0.6 μm, 21.4% by weight of silica sol, 8.0% by weight of carboxymethylcellulose, and 40.6% by weight of water. Adhesive paste was used.

(5) A coating material paste layer was formed on the outer periphery of the ceramic block 103 using a coating material paste having the same composition as the adhesive paste used in the step (4). Thereafter, this coating material paste layer was dried at 120 ° C. to produce a cylindrical honeycomb structure 100 having a diameter of 143.8 mm and a length of 150 mm, in which the coating layer 102 was formed on the outer periphery.

The cross-sectional shape of the honeycomb structure manufactured in Example 1 is as shown in FIG.
In the honeycomb structure 100, when the similar shape 105 having the area of 49% is drawn concentrically with the center of the cross section of the ceramic block 103, a part of the outer peripheral honeycomb fired body 120 is necessarily similar. 105 (see FIG. 4).

(Comparative Example 1)
(1) By performing the same steps as the steps (1) to (3) of Example 1, the porosity is 45%, the average pore diameter is 15 μm, the size is 34.3 mm × 34.3 mm × 150 mm, A honeycomb fired body made of a porous silicon carbide sintered body having a cell number (cell density) of 300 / inch ² and a cell wall thickness of 0.25 mm (10 mil) was produced.

(2) Adhesive paste is applied to the side face of the honeycomb fired body, 16 honeycomb fired bodies are bonded through the adhesive paste, and further, the adhesive paste is solidified at 180 ° C. for 20 minutes to bond. An aggregate of honeycomb fired bodies having a prism shape with a material layer thickness of 1 mm was manufactured.
Here, the same adhesive paste as the adhesive paste used in Example 1 was used as the adhesive paste.

Next, the outer periphery of the aggregate of the honeycomb fired bodies was ground using a diamond cutter to produce a cylindrical ceramic block.
Then, the coating material paste layer was formed in the outer peripheral part of the ceramic block using the coating material paste which consists of the same material as an adhesive material paste. And this coating material paste layer was dried at 120 degreeC, and the cylindrical honeycomb structure of diameter 143.8mm x length 150mm in which the coating layer was formed in the outer periphery was manufactured.

The cross-sectional shape of the honeycomb structure manufactured in Comparative Example 1 is as shown in FIG.
FIG. 5 is a cross-sectional view of the honeycomb structure 400 manufactured in Comparative Example 1. In FIG. 5, 410 is a central honeycomb fired body, 420 and 430 are outer peripheral honeycomb fired bodies, 401 is an adhesive layer, and 402 is an adhesive layer. A coating layer 403 indicates a ceramic block.
In the honeycomb structure 400, when the similar shape 405 having the area of 49% is drawn concentrically with the center of the cross section of the ceramic block 403, the outer peripheral honeycomb fired body 430 is placed outside the similar shape 405. Is located only.

(Evaluation of honeycomb structure)
The honeycomb structures manufactured in Example 1 and Comparative Example 1 were subjected to the regeneration treatment by the following method, and the regeneration rate (%) was measured by the following method based on the weight difference before and after the regeneration treatment.
Here, the smaller the regeneration rate is, the more unburned particulates are generated in the regeneration process.

(Reproduction processing)
The honeycomb structures of Example 1 and Comparative Example 1 are respectively arranged in the exhaust passage of a 2 L engine, and further, a catalyst support (diameter: honeycomb) made of commercially available cordierite is provided on the gas inflow side from the honeycomb structure. 200 mm, length: 100 mm, cell density: 400 cells / inch ² , platinum carrying amount: 5 g / L) is set as an exhaust gas purification device, engine is rotated at 3000 min ⁻¹ , torque is 50 Nm and particulates are 7 hours I collected it. The amount of particulates collected was 8 g / L.
After that, the engine is set at a rotational speed of 1250 min ⁻¹ and a torque of 60 Nm, and the filter temperature is kept constant for 1 minute. Then, post-injection is performed, and the exhaust gas temperature is raised using the oxidation catalyst in front. The particulates were burned.
The post-injection conditions were set so that the temperature of the exhaust gas flowing into the honeycomb structure after 1 minute from the start became substantially constant at 600 ° C.

(Calculation of playback rate)
The initial weight of the honeycomb structure before the particulate collection is W ₀ , the weight of the honeycomb structure after the particulate collection and before the regeneration treatment is W ₁ , and the weight of the honeycomb structure after the regeneration treatment is W _2. The regeneration rate was calculated from equation (1).
Reproduction rate = [(W ₁ −W ₀ ) − (W ₂ −W ₀ )] / (W ₁ −W ₀ ) (1)

As a result, the regeneration rate of the honeycomb structure of Example 1 was 85%.
On the other hand, the regeneration rate of the honeycomb structure of Comparative Example 1 was 70%.
This is considered to be because in the honeycomb structure of Comparative Example 1, a large amount of particulate unburned residue was generated when the regeneration process was performed.

(Second embodiment)
Hereinafter, a second embodiment, which is another embodiment of the honeycomb structure of the present invention, will be described with reference to the drawings.
FIG. 6 is a cross-sectional view of the honeycomb structure of the second embodiment.

In the honeycomb structure 200 of the present embodiment, as shown in FIG. 6, a plurality of central honeycomb fired bodies 210 and outer peripheral honeycomb fired

bodies

220 and 230 are bonded together via an adhesive layer 201 to form a ceramic block. 203, and further, a coat layer 202 is formed on the outer periphery of the ceramic block 203.
The cross-sectional shape of the central honeycomb fired body 210 is a square.
The cross-sectional shape of the outer peripheral honeycomb fired body 220 is surrounded by three

line segments

220a, 220b, and 220c and one arc 220d, and two corners (line lines) formed by two of the three line segments. The angle formed by the segment 220a and the line segment 220b and the angle formed by the line segment 220b and the line segment 220c) are both 90 °.
The cross-sectional shape of the outer peripheral honeycomb fired body 230 is surrounded by three

line segments

230a, 230b, and 230c and one arc 230d, and two corners (line lines) formed by two of the three line segments. The angle formed by the minute segment 230b and the line segment 230c and the angle formed by the line segment 230a and the line segment 230b) are 90 ° and 135 °, respectively.
That is, the center honeycomb fired body 210 is the same as the center honeycomb fired body 110 constituting the honeycomb structure of the first embodiment, and the outer peripheral honeycomb fired

bodies

220 and 230 are the honeycomb structure of the first embodiment. Although the external shape is different from that of the center-portion honeycomb fired body 110 constituting the above, its function is the same.
The honeycomb fired

bodies

210, 220, and 230 are made of a porous silicon carbide sintered body.

In the honeycomb structure 200, as shown in FIG. 6, nine central honeycomb fired bodies 210 are located at the center of the cross section of the honeycomb structure 200, and eight peripheral honeycomb fired bodies 220 around the periphery. Eight outer peripheral honeycomb fired bodies 230 are positioned, and the honeycomb structure 200 (ceramic block 203) is bound via the adhesive layer 201 so that the cross section of the honeycomb structure 200 (ceramic block 203) is circular.

In the honeycomb structure 200, when the similar shape (circular shape) 205 having an area of 49% is concentric with the center of the cross section of the ceramic block 203, all the outer peripheral honeycomb fired

bodies

220 and 230 are drawn. A part is located inside the similar shape 205.
As described above, when a part of all the outer peripheral honeycomb fired

bodies

220 and 230 are located inside the similar shape 205, the adhesive layer is formed at a position away from the center of the honeycomb structure 200 (ceramic block 203). Therefore, there is no outer peripheral honeycomb fired body that exists in isolation, so that temperature distribution hardly occurs between the central portion and the outer peripheral portion of the honeycomb structure.

Also in the honeycomb structure 200, the cross-sectional area of the central honeycomb fired body 210 is 900 to 2500 mm ² .
The reason is as described in the first embodiment.

Next, a method for manufacturing the honeycomb structure of the present embodiment will be described.
The manufacturing method of the honeycomb structure in the present embodiment is the same as the manufacturing method of the honeycomb structure in the first embodiment except for the following points.
That is, the shape of the honeycomb formed body produced in the forming step (1) of the manufacturing method of the first embodiment is the center portion shown in FIG. 6 except that either one end of the cell is not sealed. The honeycomb fired body 210 and the outer peripheral honeycomb fired

bodies

220 and 230 have substantially the same shape, and when performing the binding step (4) of the manufacturing method of the first embodiment, it is shown in FIG. Thus, except that the honeycomb fired bodies are bundled so that the central honeycomb fired body 210 and the outer peripheral honeycomb fired

bodies

220 and 230 are positioned, the method for manufacturing the honeycomb structure in the first embodiment is the same. By using the method, the honeycomb structure of the present embodiment can be manufactured.

In the honeycomb structure of the present embodiment, the same effects as the honeycomb structure of the first embodiment can be enjoyed.

(Example 2)
Examples that more specifically disclose the second embodiment of the present invention will be described below. In addition, this invention is not limited only to these Examples.

(1) Using the same method as in the forming step (1) of Example 1, the shape was substantially the same as that of the central honeycomb fired body 210 and the peripheral honeycomb fired

bodies

220 and 230 shown in FIG. Thus, a raw honeycomb molded body without cell sealing was produced.

(3) A degreasing step of degreasing the dried honeycomb formed body at 400 ° C. was performed, and further a firing step was performed at 2200 ° C. for 3 hours under an atmospheric pressure of argon atmosphere.
As a result, the porosity was 45%, the average pore diameter was 15 μm, the size was 34.5 mm × 34.5 mm × 150 mm, the number of cells (cell density) was 300 / inch ² , and the cell wall thickness was 0.1. A central honeycomb fired body 210 made of 25 mm (10 mil) porous silicon carbide sintered body;
The porosity, average pore diameter, number of cells (cell density), and cell wall thickness are the same as those of the central honeycomb fired body 210, and the cross section is surrounded by three line segments and one arc. Outer part honeycomb firing of a shape in which two corners made of two of the line segments are both 90 ° (line segment 220a = 45.6 mm, line segment 220b = 26.8 mm, line segment 220c = 41.8 mm) A body 220;
The porosity, average pore diameter, number of cells (cell density), and cell wall thickness are the same as those of the central honeycomb fired body 210, and the cross section is surrounded by three line segments and one arc. The outer circumference of the shape (line segment 230a = 24.9mm, line segment 230b = 24.5mm, line segment 230c = 41.8mm) in which the two angles of two line segments are 90 ° and 135 °, respectively Part honeycomb fired body 230 was manufactured.

(4) Adhesive paste is applied to predetermined side surfaces of the central honeycomb fired body 210 and the outer peripheral honeycomb fired

bodies

220 and 230, and nine central honeycomb fired bodies 210 are disposed through the adhesive paste. Adhering 8 outer peripheral honeycomb fired bodies 220 and 8 outer peripheral honeycomb fired bodies 230 so as to have the arrangement shown in FIG. 6, and further solidifying the adhesive paste at 180 ° C. for 20 minutes As a result, a cylindrical ceramic block 203 having an adhesive layer thickness of 1 mm was produced.
Here, the adhesive paste similar to Example (1) was used as an adhesive paste.

(5) A coating material paste layer was formed on the outer periphery of the ceramic block 203 using a coating material paste having the same composition as the adhesive paste used in the step (4). Thereafter, this coating material paste layer was dried at 120 ° C. to produce a cylindrical honeycomb structure 200 having a diameter of 203.2 mm and a length of 150 mm, on which the coating layer 202 was formed on the outer periphery.

The cross-sectional shape of the honeycomb structure manufactured in Example 2 is as shown in FIG.
In the honeycomb structure 200, when the similar shape 205 having the area of 49% is drawn concentrically with the center of the cross section of the ceramic block 203, a part of the outer peripheral honeycomb fired

bodies

220 and 230 is always included. It is located inside the similar shape 205 (see FIG. 6).

The honeycomb structure manufactured in Example 2 was subjected to a regeneration process in the same manner as in Example 1, and the regeneration rate (%) was measured based on the weight difference before and after the regeneration process.
As a result, the regeneration rate of the honeycomb structure of Example 2 was 82%.

(Other embodiments)
In the method for manufacturing the honeycomb structure of the first and second embodiments, a honeycomb fired body formed in a predetermined shape is manufactured in advance, and the honeycomb structure is manufactured. However, the honeycomb structure of the embodiment of the present invention is manufactured. You may produce a structure using the following methods, for example.
Hereinafter, another method for manufacturing the honeycomb structure of the embodiment of the present invention will be described by taking as an example the case of manufacturing the honeycomb structure of the first embodiment.

FIGS. 7A and 7B are cross-sectional views for explaining another example of the method for manufacturing a honeycomb structure according to the embodiment of the present invention.
(1) Using the same method as in (1) to (3) of the first embodiment, a honeycomb fired body in which either one end of each cell is sealed is manufactured.
At this time, a central honeycomb fired body 310 having a quadrangular cross section and an outer peripheral honeycomb fired body 320 ′ having a trapezoidal cross section are manufactured (see FIG. 7A).

(2) Next, as in the case of (4) of the first embodiment, an adhesive is used so that the central honeycomb fired body 310 and the outer peripheral honeycomb fired body 320 ′ are positioned as shown in FIG. A bundle 303 'of honeycomb fired bodies is produced by binding the paste layers and solidifying the adhesive paste layer.

(3) Next, an outer periphery processing step is performed in which a side surface of the honeycomb fired body aggregate 303 ′ is processed into a cylindrical shape by using a diamond cutter or the like, and the central honeycomb fired body 310, the outer peripheral honeycomb fired body 320, Is manufactured through the adhesive layer 301 (see FIG. 7B).
Thereafter, if necessary, a coat layer (not shown) is formed on the outer peripheral side surface of the ceramic block 303 to complete the honeycomb structure.

In the honeycomb structure of the embodiment of the present invention, the outer peripheral honeycomb fired body does not necessarily have the same cross-sectional shape. That is, in the cross section of the ceramic block, when drawing a similar shape with the area of 49% concentric with the center of the cross section, a part of each outer peripheral honeycomb fired body is not necessarily located inside the similar shape. If there is, the shape of the cross section of each outer peripheral honeycomb fired body may not be the same.
Specifically, the cross-sectional shape of the honeycomb structure may be a shape as shown in FIG. 8 (a) or FIG. 8 (b).
FIGS. 8A and 8B are cross-sectional views of a honeycomb structure according to another embodiment of the present invention.

The configuration of the honeycomb structure 500 shown in FIG. 8A is the same as that of the honeycomb structure 100 of the first embodiment except that the outer peripheral honeycomb fired

bodies

520 and 530 have different cross-sectional shapes.
That is, in the honeycomb structure 500 shown in FIG. 8A, four honeycomb fired bodies 520 and four pieces are disposed around the four central honeycomb fired bodies 510 bound through the adhesive layer 501. The honeycomb fired body 530 is bound through an adhesive layer 501 to form a ceramic block 503. A coat layer 502 is formed around the ceramic block 503.

The cross-sectional shape of the outer peripheral honeycomb fired body 520 is surrounded by two

line segments

520a and 520b and one arc 520c, and an angle formed by the two line segments (an angle formed by the

line segments

520a and 520b). Is a shape that is 90 °.
The cross-sectional shape of the outer peripheral honeycomb fired body 530 is surrounded by three

line segments

530a, 530b, and 530c and one arc 530d, and two corners (line lines) formed by two of the three line segments (line The angle formed by the segment 530b and the line segment 530c and the angle formed by the line segment 530a and the line segment 530b) are both 90 °.

In the honeycomb structure 500, when the similar shape (circular shape) 505 having an area of 49% is concentric with the center of the cross section of the ceramic block 503, all of the outer peripheral honeycomb fired

bodies

520 and 530 are drawn. A part is located inside the similar shape 505.
Therefore, also in the honeycomb structure 500 of such an embodiment, the same effect as the honeycomb structure of the first embodiment can be enjoyed.
The outer peripheral honeycomb fired

bodies

520 and 530 have the same function, although the cross-sectional shape is different from that of the outer peripheral honeycomb fired body 120.

The configuration of the honeycomb structure 600 shown in FIG. 8B is the same as the configuration of the honeycomb structure 500 shown in FIG. 8A except that the arrangement of the outer peripheral honeycomb fired

bodies

620 and 630 is different.
That is, in the honeycomb structure 600 shown in FIG. 8B, the outer peripheral honeycomb fired body 620 and the outer peripheral honeycomb fired body 630 are different from the honeycomb structure 500 shown in FIG. Are arranged alternately.
Each of the outer peripheral honeycomb fired

bodies

620 and 630 is the same as each of the outer peripheral honeycomb fired

bodies

520 and 530 except that the positions in the honeycomb structure 600 are different.

In the honeycomb structure 600, when the cross section of the ceramic block 603 is drawn with a similar shape (circular shape) 605 that is concentric with the center of the cross section and has an area of 49%, all of the outer peripheral honeycomb fired

bodies

620 and 630 are drawn. A part is located inside the similar shape 605.
Therefore, also in the honeycomb structure 600 of such an embodiment, the same operation effect as the honeycomb structure of the first embodiment can be enjoyed.
In FIG. 8B, reference numeral 602 denotes a coat layer, and 610 denotes a central honeycomb fired body.

Further, the

honeycomb structures

500 and 600 having the configurations shown in FIG. 8A and FIG. 8B are formed by bundling a required number of honeycomb fired bodies having different cross-sectional shapes through an adhesive layer, It can be manufactured by fabricating an aggregate of honeycomb fired bodies and then processing the outer periphery thereof.
This will be described in more detail with reference to FIGS. 9A and 9B, taking the case of manufacturing the honeycomb structure 500 as an example.

9A and 9B are cross-sectional views for explaining another example of the method for manufacturing a honeycomb structure according to the embodiment of the present invention.
(1) Using the same method as in (1) to (3) of the first embodiment, a honeycomb fired body in which either one end of each cell is sealed is manufactured.
At this time, a central honeycomb fired body 510 having a quadrangular cross section and outer peripheral honeycomb fired bodies 520 ′ and 530 ′ having a quadrangular cross section are manufactured (see FIG. 9A). The central honeycomb fired body 510 and the outer peripheral honeycomb fired body 530 ′ are the same honeycomb fired body.

(2) Next, as in (4) of the first embodiment, the central honeycomb fired body 510 and the outer peripheral honeycomb fired bodies 520 ′ and 530 ′ are positioned as shown in FIG. 9A. Then, the honeycomb fired body aggregate 503 ′ is manufactured by binding through the adhesive paste layer and solidifying the adhesive paste layer.

(3) Next, an outer periphery processing step is performed in which the side surface of the honeycomb fired body aggregate 503 ′ is processed into a cylindrical shape by using a diamond cutter or the like, and the central honeycomb fired body 510 and the outer peripheral honeycomb fired body 520 are processed. A ceramic block 503 in which 530 is bound through an adhesive layer 501 is manufactured (see FIG. 9B).
Thereafter, if necessary, a coat layer (not shown) is formed on the outer peripheral side surface of the ceramic block 503 to complete the honeycomb structure.

In the honeycomb structure of the embodiment of the present invention, the end of the cell may not be sealed. Such a honeycomb structure can be used as a catalyst carrier.

The shape of the honeycomb fired body is not particularly limited, but it is preferably a shape that is easily bundled when the honeycomb fired bodies are bound together to produce a honeycomb structure. A square, a rectangle, a hexagon, a fan shape, etc. are mentioned.

The shape of the honeycomb structure of the embodiment of the present invention is not limited to the cylindrical shape, and may be an elliptical column shape.

Specifically, for example, a honeycomb structure having a cross-sectional shape as shown in FIG. 10 may be used.
FIG. 10 is a cross-sectional view of a honeycomb structure according to another embodiment of the present invention.

In the honeycomb structure 700 shown in FIG. 10, a plurality of central honeycomb fired bodies 710 and outer peripheral honeycomb fired

bodies

720, 730, and 740 are bundled together via an adhesive layer 701 to form a ceramic block 703. Further, a coat layer 702 is formed on the outer periphery of the ceramic block 703.
The cross-sectional shape of the central honeycomb fired body 710 is a square.
The cross-sectional shape of the outer peripheral honeycomb fired body 720 is surrounded by three

line segments

720a, 720b, and 720c and one elliptical arc 720d, and two corners (line The angle formed by the segment 720a and the line segment 720b and the angle formed by the line segment 720b and the line segment 720c are both 90 °.
The cross-sectional shape of the outer peripheral honeycomb fired body 730 is surrounded by three

line segments

730a, 730b, 730c and one elliptical arc 730d, and two corners (line The angle formed by the segment 730b and the line segment 730c and the angle formed by the line segment 730a and the line segment 730b) are 90 ° and 135 °, respectively.
The cross-sectional shape of the outer peripheral honeycomb fired body 740 is surrounded by three

line segments

740a, 740b, and 740c and one elliptical arc 740d, and two corners (line The angle formed by the segment 740a and the line segment 740b and the angle formed by the line segment 740b and the line segment 740c) are both 135 °.
That is, the central honeycomb fired body 710 is the same as the central honeycomb fired body 110 constituting the honeycomb structure of the first embodiment, and the outer peripheral honeycomb fired

bodies

720, 730, and 740 are the honeycombs of the first embodiment. Although the appearance shape is different from that of the central honeycomb fired body 110 constituting the structure, its function is the same.

The honeycomb structure 700 includes three central honeycomb fired bodies 710 bound via an adhesive layer 701, two peripheral honeycomb fired bodies 720 and four peripheral honeycomb fired bodies positioned around the central fired body 710. 730 and two outer peripheral honeycomb fired bodies 740, and the honeycomb structure 700 (ceramic block 703) is bound via an adhesive layer 701 so that the cross section of the honeycomb structure 700 (ceramic block 703) is elliptical.

In the honeycomb structure 700, when the similar shape (elliptical shape) 705 having a concentric area of 49% is drawn in the cross section of the ceramic block 703, all the outer peripheral honeycomb fired

bodies

720 and 730 are drawn. , 740 is located inside the similar shape 705.
Thus, when a part of all the outer peripheral honeycomb fired

bodies

720, 730, and 740 are located inside the similar shape 705, a position away from the center of gravity in the cross section of the honeycomb structure 700 (ceramic block 703). Therefore, there is no outer peripheral honeycomb fired body that exists in isolation through the adhesive layer, so that temperature distribution hardly occurs between the central portion and the outer peripheral portion of the honeycomb structure.

Examples of the inorganic binder contained in the adhesive paste include silica sol and alumina sol. These may be used alone or in combination of two or more. Among inorganic binders, silica sol is desirable.

Examples of the inorganic particles contained in the adhesive paste include inorganic particles made of carbide, nitride, and the like. Specifically, inorganic particles made of silicon carbide, silicon nitride, boron nitride, and the like can be given. . These may be used alone or in combination of two or more. Among the inorganic particles, inorganic particles made of silicon carbide having excellent thermal conductivity are desirable.

Examples of the inorganic fibers and / or whiskers contained in the adhesive paste include inorganic fibers and / or whiskers made of silica-alumina, mullite, alumina, silica, and the like. These may be used alone or in combination of two or more. Among inorganic fibers, alumina fibers are desirable.

The porosity of the honeycomb fired body is not particularly limited, but is desirably 35 to 60%.
If the porosity is less than 35%, the honeycomb structure of the embodiment of the present invention may be clogged immediately. On the other hand, if the porosity exceeds 60%, the strength of the honeycomb fired body decreases. This is because they can be easily destroyed.

The average pore size of the honeycomb fired body is desirably 5 to 30 μm.
If the average pore diameter is less than 5 μm, the particulates may easily clog. On the other hand, if the average pore diameter exceeds 30 μm, the particulates pass through the pores and collect the particulates. This is because it may not be able to function as a filter.

The porosity and pore diameter can be measured by a conventionally known method such as a mercury intrusion method, an Archimedes method, or a measurement using a scanning electron microscope (SEM).

The cell density in the cross section of the honeycomb structure is not particularly limited, but a desirable lower limit is 31.0 / cm ² (200 / in ² ), and a desirable upper limit is 93 / cm ² (600 / in ² ). The more desirable lower value is 38.8 / cm ² (250 / in ² ), and the more desirable upper limit is 77.5 / cm ² (500 / in ² ).
The thickness of the cell wall of the honeycomb structure is not particularly limited, but is preferably 0.1 to 0.4 mm.

The main component of the constituent material of the honeycomb structure is not limited to silicon carbide, and other ceramic raw materials include, for example, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, zirconium carbide, Examples thereof include carbide ceramics such as titanium carbide, tantalum carbide, and tungsten carbide, and oxide ceramics such as cordierite and aluminum titanate.
Of these, non-oxide ceramics are preferred, and silicon carbide is particularly preferred. It is because it is excellent in heat resistance, mechanical strength, thermal conductivity and the like. In addition, ceramic raw materials such as silicon-containing ceramics in which metallic silicon is blended with the above-described ceramics, ceramics bonded with silicon or a silicate compound can be cited as constituent materials, and among these, silicon carbide is blended with silicon carbide. (Silicon-containing silicon carbide) is desirable.
In particular, a silicon-containing silicon carbide ceramic containing 60 wt% or more of silicon carbide is desirable.

The particle size of the ceramic powder is not particularly limited, but it is preferable that the size of the honeycomb fired body manufactured through the subsequent firing step is small compared to the size of the degreased honeycomb formed body.

It does not specifically limit as an organic binder mixed with the said wet mixture, For example, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethyleneglycol etc. are mentioned. Of these, methylcellulose is desirable. The amount of the organic binder is usually 1 to 10 parts by weight with respect to 100 parts by weight of the ceramic powder.
The plasticizer mixed with the wet mixture is not particularly limited, and examples thereof include glycerin.
The lubricant mixed in the wet mixture is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether. Specific examples include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the wet mixture.

In preparing the wet mixture, a dispersion medium liquid may be used. Examples of the dispersion medium liquid include water, an organic solvent such as benzene, and an alcohol such as methanol.
Furthermore, a molding aid may be added to the wet mixture.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol and the like.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide-based ceramics, spherical acrylic particles, and graphite may be added to the wet mixture as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

The encapsulant paste for sealing the cells is not particularly limited, but it is desirable that the encapsulant produced through a subsequent process has a porosity of 30 to 75%. For example, a paste-like material similar to a wet mixture Can be used.

The honeycomb structure may support a catalyst for purifying exhaust gas. As the catalyst to be supported, for example, a noble metal such as platinum, palladium, rhodium or the like is desirable, and among these, platinum is more desirable. Further, as other catalysts, for example, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can be used. These catalysts may be used alone or in combination of two or more.

The bundling step in the method for manufacturing a honeycomb structure according to the embodiment of the present invention includes, for example, a ceramic block (or an aggregate of honeycomb fired bodies) to be produced in addition to the method of applying the adhesive paste to the side surfaces of each honeycomb fired body. Alternatively, the honeycomb fired bodies may be temporarily fixed in a form having substantially the same shape as the shape, and an adhesive paste may be injected between the honeycomb fired bodies.

1 is a perspective view schematically showing a honeycomb structure according to a first embodiment. FIG. 2 (a) is a perspective view schematically showing the central honeycomb fired body of the first embodiment, and FIG. 2 (b) is a cross-sectional view taken along the line AA of FIG. 2 (a). FIG. 3 is a perspective view schematically showing an outer peripheral honeycomb fired body of the first embodiment. 3 is a cross-sectional view showing a cross-sectional shape of a honeycomb structure manufactured in Example 1. FIG. 3 is a cross-sectional view showing a cross-sectional shape of a honeycomb structure manufactured in Comparative Example 1. FIG. It is sectional drawing of the honeycomb structure of 2nd embodiment. FIGS. 7A and 7B are cross-sectional views illustrating another example of the method for manufacturing a honeycomb structure according to the embodiment of the present invention. FIGS. 8A and 8B are cross-sectional views of honeycomb structures according to other embodiments of the present invention. 9A and 9B are cross-sectional views for explaining another example of the method for manufacturing a honeycomb structure according to the embodiment of the present invention. FIG. 10 is a cross-sectional view of a honeycomb structure according to another embodiment of the present invention.

Explanation of symbols

100, 200

Honeycomb structure

101, 201

Adhesive layer

102, 202

Coat layer

103, 203

Ceramic block

110, 210 Central honeycomb fired

body

120, 220, 230 Peripheral honeycomb fired

body

111, 121

Cell

112, 122

Sealing material

113, 123 cell wall

Claims

A columnar honeycomb fired body in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall is a cylindrical or elliptical columnar honeycomb structure comprising a plurality of ceramic blocks bound through an adhesive layer. ,
The plurality of honeycomb fired bodies are composed of a central part honeycomb fired body located in the central part of the honeycomb structure and an outer peripheral part honeycomb fired body constituting a part of the outer peripheral side surface of the ceramic block,
The central honeycomb fired body has an area of a cross section perpendicular to the longitudinal direction of 900 to 2500 mm 2 ;
In the cross section perpendicular to the longitudinal direction of the ceramic block, when a similar shape having an area of 49% is concentric with the center of the cross section, a part of the outer peripheral honeycomb fired body is always inside the similar shape. A honeycomb structure characterized by being located in a position.