JP2009255037A - Honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a honeycomb structure which prevents breakage, position deviation and falling due to cracks generated with an adhesive material layer as an origin. <P>SOLUTION: This invention relates to the honeycomb structure 10 wherein a plurality of columnar honeycomb sintered compacts having many cells longitudinally arranged side by side are bound through an adhesive material layer 40. The plurality of honeycomb sintered compacts are composed of a center part honeycomb sintered compact 20 positioned at the center part of the honey structure and an outer peripheral part honeycomb sintered compact 30 for configuring a part of the outer peripheral surface of the honey comb structure 10. For the outer peripheral part honeycomb sintered compact 30, recesses and projections are formed on at least one of the surfaces in contact with the adhesive material layer 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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.
Therefore, various honeycomb structures made of porous ceramics have been proposed as diesel particulate filters (hereinafter also simply referred to as DPF) that can collect particulates in exhaust gas and purify 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).
Further, there has been proposed a honeycomb structure manufactured by binding a plurality of honeycomb fired bodies, each of which is produced by extrusion molding into a predetermined shape in advance, through an adhesive layer.
(For example, refer to Patent Document 2).

International Publication No. 01/23069 Pamphlet JP 2004-154718 A

When the honeycomb structure is used as a DPF, after a predetermined amount of particulates is collected, a regeneration process is performed to burn and remove the particulates.
In this regeneration process, high-temperature exhaust gas discharged from the internal combustion engine flows into cells near the center of the honeycomb structure that is relatively easy to flow. Further, since the particulates are collected more in the vicinity of the central part of the honeycomb structure, the burning of the particulates starts near the central part of the honeycomb structure.
Therefore, the temperature in the vicinity of the center portion of the honeycomb structure tends to be higher than the temperature in the vicinity of the outer peripheral portion of the honeycomb structure, resulting in a temperature difference in the radial direction of the honeycomb structure.
When such a temperature difference occurs, a difference occurs in the degree of thermal expansion between the vicinity of the center portion and the outer periphery of the honeycomb structure, and stress is generated at the outer periphery of the honeycomb structure.
As a result, cracks may occur starting from the adhesive layer, and the honeycomb structure may be damaged. In addition, cracks develop, the adhesive layer breaks, and pressure due to the exhaust gas is applied, so that the honeycomb fired body may be misaligned or fall off the honeycomb structure.

An object of the present invention is to prevent breakage of the honeycomb structure, displacement of the honeycomb fired body, and dropping of the honeycomb fired body.

The inventors of the present invention have studied to prevent the honeycomb structure from being damaged during the regeneration process, the honeycomb fired body from being displaced, and the honeycomb fired body from falling off, and the present invention has been completed.
That is, the invention of claim 1 is a honeycomb structure in which a plurality of columnar honeycomb fired bodies in which a large number of cells are arranged in parallel in the longitudinal direction with a cell wall interposed therebetween are bound via an adhesive layer. ,
The plurality of honeycomb fired bodies includes a central honeycomb fired body located at the center of the honeycomb structure and an outer peripheral honeycomb fired body that constitutes a part of the outer peripheral surface of the honeycomb structure.
The outer peripheral honeycomb fired body is a honeycomb structure characterized in that unevenness is formed on at least one of the surfaces in contact with the adhesive layer.
In the present specification, the center-portion honeycomb fired body refers to a honeycomb fired body that does not constitute the outer peripheral surface of the honeycomb structure in a cross section perpendicular to the longitudinal direction of the honeycomb structure.

In the honeycomb structure according to the first aspect, irregularities are formed on a predetermined surface of the peripheral honeycomb fired body, and the adhesive strength between the peripheral honeycomb fired body and the adhesive layer is high. For this reason, cracks are hardly generated starting from the adhesive layer. Accordingly, it is possible to prevent the honeycomb structure from being damaged, the honeycomb fired body from being displaced, and the honeycomb fired body from being detached.

This will be described in detail below with reference to the drawings. First, the overall configuration of the honeycomb structure according to claim 1 will be described.
FIG. 1 is a perspective view schematically showing a honeycomb structure according to claim 1.
As shown in FIG. 1, the honeycomb structure 10 includes four central honeycomb fired bodies 20 positioned in the central part of the honeycomb structure 10 and a part of the outer peripheral surface 11 of the honeycomb structure 10. The outer peripheral honeycomb fired bodies 30 and the adhesive layer 40 that exists between these honeycomb fired bodies (the central honeycomb fired body 20 and the outer peripheral honeycomb fired body 30) and bonds the honeycomb fired bodies to each other. It consists of and.

The configuration of the central honeycomb fired body 20 will be described below with reference to the drawings.
Fig. 2 (a) is a perspective view schematically showing a central honeycomb fired body constituting the honeycomb structure according to claim 1, and Fig. 2 (b) is a view showing the center shown in Fig. 2 (a). It is an AA line sectional view of a partial honeycomb calcination object.

As shown in FIG. 2 (a), the central honeycomb fired body 20 has a substantially square pillar shape having a substantially square shape in cross section including four planes 20a having the same area, as shown in FIG. 2 (b). In the longitudinal direction (indicated by a double-headed arrow B in FIG. 2A), a large number of cells 21 are arranged side by side across the cell wall 22, and either end of the cells 21 is sealed with a sealing material 23. It has been stopped. Therefore, the exhaust gas G (see the arrow in FIG. 2B) that flows into the cell 21 with one end face opened always passes through the cell wall 22 separating the cell 21, and then the other cell with the other end face open. 21 flows out.
Therefore, the cell wall 22 functions as a filter for collecting PM and the like.

The configuration of the outer peripheral honeycomb fired body will be described below with reference to the drawings.
Fig. 3 (a) is a perspective view schematically showing an outer periphery honeycomb fired body constituting the honeycomb structure according to claim 1, and Fig. 3 (b) is an outer periphery shown in Fig. 3 (a). FIG. 4 is a perspective view of a partial honeycomb fired body observed from a direction different from that in FIG.

As shown in FIGS. 3 (a) and 3 (b), the outer peripheral honeycomb fired body 30 is longitudinally similar to the central honeycomb fired body 20 shown in FIGS. 2 (a) and 2 (b). A large number of cells 31 are arranged side by side across the cell wall 32, and either end of the cell 31 is sealed with a sealing material 33. Therefore, like the central honeycomb fired body 20, the cell wall 32 functions as a filter for collecting PM and the like.
Moreover, the shape is a polygonal column shape including four surfaces of the surface 30a, the surfaces 30b and 30c, and the surface 30d having the same area. Specifically, of the four surfaces 30a, 30b, 30c, and 30d, the surface 30a is a curved surface.
Further, the surface 30c facing the curved surface 30a is provided with irregularities along the cross-sectional shape of the cell.
The remaining two surfaces 30b and 30d are flat. In the following description, a surface on which unevenness is formed is also referred to as an uneven surface.

The detailed structure of the honeycomb structure according to claim 1 will be described below with reference to the drawings.
FIG. 4 is a plan view schematically showing a cross section when the honeycomb structure according to claim 1 is cut perpendicularly to the longitudinal direction.

As shown in FIG. 4, in the honeycomb structure 10, the curved surface 30 a of the outer peripheral honeycomb fired body 30 forms a part of the outer peripheral surface of the honeycomb structure 10.
Further, the flat surface 30 b is bonded to the flat surface 30 b of another adjacent peripheral honeycomb fired body 30 via the adhesive layer 40.
The uneven surface 30 c is bonded to the flat surface 20 a of the central honeycomb fired body 20 via the adhesive layer 40.
The plane 30 d is bonded to another plane 30 d of another outer peripheral honeycomb fired body 30 through an adhesive layer 40.

Here, the contact area between the uneven surface 30c of the outer peripheral honeycomb fired body 30 and the adhesive layer 40 is the contact area between the plane of the honeycomb fired body on which the unevenness is not formed and the adhesive layer (the central honeycomb fired body 20). The contact area between the flat surface 20a and the adhesive layer 40, the contact area between the flat surface 30b of the outer peripheral honeycomb fired body 30 and the adhesive layer 40, or the flat surface 30d of the outer peripheral honeycomb fired body 30 and the adhesive layer 40 It is larger than the contact area.
Therefore, the adhesive strength between the outer peripheral honeycomb fired body 30 and the adhesive layer 40 is increased, and cracks are hardly generated starting from the adhesive layer 40.
Therefore, the honeycomb structure of the present invention prevents damage to the honeycomb structure 10 due to cracks generated from the adhesive layer, displacement of the outer peripheral honeycomb fired body 30, and dropping of the outer peripheral honeycomb fired body 30. be able to.

The honeycomb structure according to claim 2 is the invention according to claim 1, wherein one of the surfaces of the outer peripheral honeycomb fired body on which the unevenness is formed has the largest area among the surfaces in contact with the adhesive layer. It is a small side.
In the honeycomb structured body according to claim 2, the unevenness is formed on the surface having the smallest area among the surfaces of the outer peripheral honeycomb fired body. Therefore, the contact area between the surface and the adhesive layer is larger than when the unevenness is not formed on the surface, and the outer peripheral honeycomb fired body and the adhesive layer in contact with the surface The adhesive strength is high. Therefore, cracks hardly occur starting from the adhesive layer in contact with the surface having the smallest area among the surfaces of the outer peripheral honeycomb structure.
Therefore, the honeycomb structure according to claim 2 is particularly suitable for enjoying the effects of the present invention.
In the present specification, when the areas of all the surfaces of the outer peripheral honeycomb fired body are equal to each other, any surface is the surface having the smallest area among the surfaces in contact with the adhesive layer.

A honeycomb structure according to a third aspect is the invention according to the first or second aspect, wherein one of the surfaces of the outer peripheral portion honeycomb fired body on which the unevenness is formed is different from the other outer peripheral honeycomb fired body and the above It is a surface in contact with the adhesive layer.
As described above, in the regeneration process, stress is generated at the outer peripheral portion of the honeycomb structure. For this reason, cracks are likely to be generated starting from the adhesive layer that bonds the outer peripheral honeycomb fired bodies that constitute part of the outer peripheral portion of the honeycomb structure.
However, in the honeycomb structure according to claim 3, the unevenness is formed on the surface of the outer peripheral honeycomb fired body, which is in contact with the other outer peripheral honeycomb fired body through the adhesive layer. . Therefore, compared with the case where the unevenness is not formed on the surface, the contact area between the surface and the adhesive layer is large, and the outer peripheral honeycomb fired body and the outer peripheral honeycomb fired body are bonded to each other. The adhesive strength with the adhesive layer is increased. Therefore, cracks are unlikely to occur starting from the adhesive layer that bonds the outer peripheral honeycomb fired bodies together.
Therefore, the honeycomb structure according to claim 3 is particularly suitable for enjoying the effects of the present invention.

The honeycomb structure according to claim 4 is the invention according to any one of claims 1 to 3, wherein an area of a cross section perpendicular to a longitudinal direction of the outer peripheral honeycomb fired body is a length of the central honeycomb fired body. It is larger than the cross-sectional area perpendicular to the direction.
Even the honeycomb structure according to claim 4 having such a configuration can preferably enjoy the effects of the present invention.

(First embodiment)
In the honeycomb structure according to the first embodiment which is an embodiment of the present invention, in the honeycomb structure according to claim 1, one of the surfaces on which the unevenness of the outer peripheral honeycomb fired body is formed is an adhesive. Among the surfaces in contact with the layer, the surface has the smallest area, and one of the surfaces on which the unevenness of the outer peripheral honeycomb fired body is formed is in contact with the other outer peripheral honeycomb fired body through the adhesive layer. It is a surface.

Hereinafter, the honeycomb fired body constituting the honeycomb structure of the first embodiment will be described with reference to the drawings.
The shape of the central honeycomb fired body is the same as that of the central honeycomb fired body constituting the honeycomb structure according to claim 1, and thus the description thereof is omitted.

The outer peripheral honeycomb fired body will be described with reference to the drawings.
Fig. 5 (a) is a perspective view schematically showing the outer peripheral honeycomb fired body constituting the honeycomb structure of the first embodiment, and Fig. 5 (b) is an outer peripheral portion shown in Fig. 5 (a). It is the perspective view which observed the honeycomb calcination object from the direction different from Drawing 5 (a).

As shown in FIG. 5A and FIG. 5B, in the outer peripheral honeycomb fired body 130, like the central honeycomb fired body 120, a large number of cells 131 are arranged side by side across the cell wall 132 in the longitudinal direction. One end of the cell 131 is sealed with a sealing material 133. Therefore, the cell wall 132 functions as a filter for collecting PM and the like.
Further, the shape is a polygonal column shape including four surfaces of a surface 130a, a surface 130b and a surface 130c having the same area, and a surface 130d. Specifically, of the four surfaces 130a, 130b, 130c, and 130d, the surface 130a and the surface 130d with the smallest area are uneven surfaces formed with unevenness along the cross-sectional shape of the cell. The remaining two surfaces 130b and 130c are flat.

A detailed configuration of the honeycomb structure 100 of the present embodiment will be described with reference to FIG.
FIG. 6 is a cross-sectional view schematically showing a cross section when the honeycomb structure of the first embodiment is cut perpendicularly to the longitudinal direction. Here, the outer peripheral honeycomb fired body 130 shown in FIGS. 5A and 5B is used as the outer peripheral honeycomb fired body.

As shown in FIG. 6, the honeycomb structure 100 of the present embodiment includes four central honeycomb fired bodies 120 positioned at the central part of the honeycomb structure 100, similarly to the honeycomb structure according to claim 1. And 8 outer peripheral honeycomb fired bodies 130 constituting a part of the outer peripheral surface of the honeycomb structure 100, and these honeycomb fired bodies (the central honeycomb fired body 120 and the outer peripheral honeycomb fired body 130). The honeycomb fired bodies are composed of an adhesive layer 140 that bonds the honeycomb fired bodies together.

As shown in FIG. 6, the adhesive layer (coat layer) 140 is not formed on the uneven surface 130a of the outer peripheral honeycomb fired body 130, and the uneven surface 130a is a part of the outer peripheral surface of the honeycomb structure 100. Is forming.
The uneven surface 130 d is bonded to the uneven surface 130 d of another adjacent peripheral honeycomb fired body 130 via the adhesive layer 140.
The flat surface 130 b is bonded to the flat surface 130 b of another adjacent outer peripheral honeycomb fired body 130 via the adhesive layer 140.
The flat surface 130 c is bonded to the flat surface 120 a of the central honeycomb fired body 120 via the adhesive layer 140.
That is, in the honeycomb structure 100 of the present embodiment, irregularities are formed on the surface 130d having the smallest area among the surfaces 130b, 130c, and 130d that are in contact with the adhesive layer 140 of the outer peripheral honeycomb fired body 130.

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, in order to produce honeycomb fired bodies of various shapes, an extrusion mold corresponding to the cross-sectional shape of the honeycomb fired body may be 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) Subsequently, a degreasing step of heating the organic matter in the honeycomb formed body in a degreasing furnace is performed, and the honeycomb body is transported to a firing furnace, and the firing step is performed to produce a honeycomb fired body.
In addition, as conditions for the degreasing step and the firing step, the conditions conventionally used when manufacturing a honeycomb fired body can be applied.
Through the above steps, the central honeycomb fired body and the outer peripheral honeycomb fired body can be manufactured.

(4) Further, an adhesive paste is applied to each of the predetermined side surfaces of the center-portion honeycomb fired body and the peripheral-portion honeycomb fired body in which predetermined ends of each cell are sealed to form an adhesive paste layer. Then, a step of laminating other honeycomb fired bodies sequentially on the adhesive paste layer is repeated to perform a binding step of manufacturing a honeycomb structure having a predetermined shape in which the 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.
In addition, if necessary, a coating layer forming step may be performed in which a sealing material paste is applied to the outer periphery of the honeycomb structure, dried and solidified to form a coating layer.
Here, the same paste as the adhesive paste is used as the sealing material paste. In addition, you may use the paste of a different composition as a coating layer paste.
Through the above steps, the honeycomb structure of the present embodiment can be manufactured.

Below, it enumerates about the effect of the honeycomb structure of this embodiment.
(1) In the honeycomb structure of the present embodiment, unevenness is formed on the surface of the outer peripheral honeycomb fired body that is in contact with the adhesive layer and the surface that is bonded to the other outer peripheral honeycomb fired body via the adhesive layer. Thus, the adhesive strength between the outer peripheral honeycomb fired body and the adhesive layer for bonding the outer peripheral honeycomb fired bodies is high. Therefore, cracks hardly occur starting from the adhesive layer that bonds the outer peripheral honeycomb fired bodies. Therefore, the honeycomb structure of the present embodiment can prevent the honeycomb structure from being damaged, the peripheral honeycomb fired body from being displaced, and the peripheral honeycomb fired body from falling off.

(2) In the honeycomb structure of the present embodiment, one of the surfaces of the outer peripheral honeycomb fired body on which the unevenness is formed is the surface having the smallest area among the surfaces in contact with the adhesive layer.
Therefore, compared with the case where the unevenness is not formed on the surface, the contact area between the surface and the adhesive layer is increased, and the adhesive strength between the outer peripheral honeycomb fired body and the adhesive layer is increased. It is high.
Therefore, the honeycomb structure of the present embodiment is particularly suitable for enjoying the effects of the present invention.

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 (methylcellulose), 2.8% by weight of lubricant (Unilube manufactured by NOF Corporation, NOF Corporation), 1.3% by weight of glycerin, and water After adding 13.8% by weight and kneading to obtain a wet mixture, a molding step of extrusion molding is performed.
In this step, by changing the shape of the extrusion mold, the center honeycomb fired body 20 shown in FIG. 2 (a) and FIG. The raw honeycomb molded body in which the cells to be fired bodies are not sealed, and the outer peripheral honeycomb fired body 130 shown in FIGS. 5 (a) and 5 (b) have substantially the same shape, and after firing. A raw honeycomb molded body in which the cells that become the outer peripheral honeycomb fired body were not plugged was produced.

(2) Next, the raw honeycomb formed body is dried using a microwave dryer to obtain a dried honeycomb formed body, and then a predetermined cell is filled with a sealing material paste having the same composition as the wet mixture. Then, the dried body of the honeycomb formed body filled with the sealing material paste was dried again using a 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.
Thereby, it is the same shape as the center part honeycomb calcination object 20 shown in Drawing 2 (a) and Drawing 2 (b), a porosity is 45%, an average pore diameter is 15 micrometers, and a size is 34.3 mm x A central honeycomb fired body 120 made of a porous silicon carbide sintered body having physical properties of 34.3 mm × 150 mm, a cell density of 300 cells / inch ² , and a cell wall thickness of 0.25 mm (10 mil); 5 (a) and 5 (b), the outer peripheral honeycomb fired body having the same porosity, average pore diameter, cell density, and cell wall thickness as the central honeycomb fired body 120 130.

(4) Adhesive paste is applied to predetermined side surfaces of the central honeycomb fired body 120 and the outer peripheral honeycomb fired body 130, and four central honeycomb fired bodies 120 and the outer peripheral part are interposed through the adhesive paste. By bonding the eight honeycomb fired bodies 130 so as to have the arrangement shown in FIG. 6 and further heating at 180 ° C. for 20 minutes to solidify the adhesive paste, the thickness of the adhesive layer 140 is 1 mm. A cylindrical honeycomb structure was manufactured.
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.

The cross-sectional shape of the honeycomb structure manufactured in Example 1 is as shown in FIG.
That is, the honeycomb structure 100 has a configuration in which irregularities are formed on the surface 130 a and the surface 130 d of the outer peripheral honeycomb fired body 130. In addition, the surface (uneven surface) 130 d on which the unevenness is formed is the surface having the smallest area among the surfaces in contact with the adhesive layer 140 and is bonded to the uneven surface 130 d of the other outer peripheral honeycomb fired body 130. It contacts through the material layer 140 (refer FIG. 6).

(Comparative Example 1)
In the same manner as in step (1) of Example 1, a raw honeycomb formed body that was to be the fired body of the central part after firing was produced.
Further, by changing the shape of the extrusion mold, the surface corresponding to the uneven surface 130a of the outer peripheral honeycomb fired body manufactured in Example 1 is a curved surface, and the surface corresponding to the uneven surface 130d is a flat surface. A raw honeycomb molded body having the same shape as that of the outer peripheral honeycomb fired body manufactured in Example 1 except that the outer peripheral honeycomb fired body was formed after firing was manufactured. By performing the steps (2) to (4) of Example 1 using these raw honeycomb molded bodies, the outer peripheral portion honeycomb in the shape of the cross section of the honeycomb structure manufactured in Example 1 shown in FIG. A honeycomb structure having the same shape as that of Example 1 was manufactured except that the surface corresponding to the uneven surface 130a of the fired body 130 was a curved surface and the surface corresponding to the uneven surface 130d was a flat surface.

(Evaluation of honeycomb structure)
The honeycomb structure manufactured in Example 1 and Comparative Example 1 was subjected to a cycle test by the following method, so that the adhesive layer after the cycle test was damaged, the honeycomb fired body was misaligned, and the honeycomb The presence or absence of falling off of the fired body was confirmed.

(Cycle test)
First, the honeycomb structures according to Example 1 and Comparative Example 1 are arranged in the exhaust passage of the engine, and further, a commercially available catalyst carrier (diameter: 144 mm, length: 100 mm, cell density) on the gas inflow side from the honeycomb structure. : 400 cells / inch ² , platinum carrying amount: 5 g / L) was set as an exhaust gas purifier, and the particulate matter was collected for 9 hours at an engine speed of 3000 min ⁻¹ and a torque of 50 Nm. The amount of particulates collected was 10 g / L.

Thereafter, the engine was set at a rotational speed of 1250 min ⁻¹ and a torque of 60 Nm, and the honeycomb structure was held at a constant temperature for 1 minute, followed by post-injection to distribute the exhaust gas to the oxidation catalyst on the gas inflow side. The exhaust temperature was raised to burn the particulates.
The post-injection conditions were set so that the central temperature of the honeycomb structure became substantially constant at 600 ° C. for 1 minute after the start. And after repeating the said process 20 times, it was observed whether the crack etc. generate | occur | produced in the honeycomb structure.

As a result, in the honeycomb structure of Example 1, the honeycomb structure was not damaged, the honeycomb fired body was misaligned, and the honeycomb fired body was not dropped even after the cycle test.
On the other hand, in the honeycomb structure of Comparative Example 1, cracks occurred in the adhesive layer, and the honeycomb structure was damaged. In addition, some of the honeycomb fired bodies had fallen off. This is considered to be because the bonding strength between the honeycomb fired bodies was inferior in the honeycomb structure of Comparative Example 1 as compared with the stress generated in the outer peripheral portion of the honeycomb structure by the repeated regeneration treatment. .

The honeycomb structure according to the first embodiment includes an outer periphery having the shape shown in FIG. 7 in addition to the center honeycomb fired body having the shape shown in FIG. 2 and the outer peripheral honeycomb fired body having the shape shown in FIG. It may be configured using a partial honeycomb fired body.
FIG. 7 (a) is a perspective view schematically showing an outer peripheral honeycomb fired body different from the outer peripheral honeycomb fired body shown in FIGS. 5 (a) and 5 (b), and FIG. 7 (b). Fig. 8 is a perspective view of the outer peripheral honeycomb fired body shown in Fig. 7 (a) observed from a direction different from Fig. 7 (a).
The outer peripheral honeycomb fired body 250 shown in FIGS. 7A and 7B has irregularities formed on the surfaces 250b and 250d facing each other, and the remaining surfaces 250a and 250c are flat. Has the same configuration as that of the central honeycomb fired body shown in FIG.

FIG. 8 shows the configuration of the honeycomb structure of the first embodiment using the honeycomb fired body shown in FIGS. 7 (a) and 7 (b).
FIG. 8 is a cross-sectional view schematically showing a cross section when the honeycomb structure using the outer peripheral honeycomb fired body shown in FIGS. 7A and 7B is cut perpendicularly to the longitudinal direction.
As shown in FIG. 8, the honeycomb structure 200 includes nine central honeycomb fired bodies 220 positioned at the center of the honeycomb structure 200 and twelve pieces constituting a part of the outer peripheral surface of the honeycomb structure 200. It exists between the peripheral honeycomb fired body 230 (250) and these honeycomb fired bodies (the central honeycomb fired body 220, the peripheral honeycomb fired body 230 (250)), and the honeycomb fired bodies are bonded to each other. It is composed of an adhesive layer 240 and a coat layer 260 that forms the outer peripheral surface of the honeycomb structure 200. The outer peripheral honeycomb fired body is composed of eight outer peripheral honeycomb fired bodies 230 having different shapes and the four outer peripheral honeycomb fired bodies 250 shown in FIGS. 7 (a) and 7 (b). Has been.
Also in the honeycomb structure 200 having such a configuration, unevenness is formed on at least one surface 230d (250b and 250d) of the surfaces in contact with the adhesive layer 240 of the outer peripheral honeycomb fired body 230 (250). .
Moreover, the surface 230d (250b and 250d) where the unevenness is formed is the surface having the smallest area among the surfaces in contact with the adhesive layer 240 of the outer peripheral honeycomb fired body 230 (250).

(Other embodiments)
In the method for manufacturing the honeycomb structure of the first embodiment, the honeycomb structure is manufactured in advance by manufacturing a honeycomb fired body formed into a predetermined shape. For example, you may produce using the following methods.
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. 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) Manufacturing a honeycomb fired body in which any one end of each cell is sealed using the same method as the steps (1) to (3) for manufacturing the honeycomb structure of the first embodiment. .
At this time, the central honeycomb fired body 320 having substantially the same shape as the central honeycomb fired body 20 shown in FIGS. 2 (a) and 2 (b), as shown in FIG. 9 (a), An outer peripheral honeycomb fired body 330 ′ having a trapezoidal shape and having an uneven surface formed on the surface 330d ′ is manufactured.
The unevenness of the surface 330d 'is not shown in the drawing.

(2) Next, as in step (4) of the first embodiment, bonding is performed so that the central honeycomb fired body 320 and the outer peripheral honeycomb fired body 330 ′ are positioned as shown in FIG. 9A. The honeycomb fired body aggregate 300 ′ is manufactured by binding the material paste layers and solidifying the adhesive paste layer.

(3) Next, an outer periphery processing step is performed in which the side surface of the aggregated body 300 ′ of the honeycomb fired body is processed into a cylindrical shape by using a diamond cutter or the like, and the central honeycomb fired body 320, the outer peripheral honeycomb fired body 330, Is manufactured through the adhesive layer 340 (see FIG. 9B).
In the surface 330d of the honeycomb structure 300 manufactured in this way, irregularities are formed along the cross-sectional shape of the cell. The unevenness of the surface 330d is not shown in the drawing.
If necessary, a coat layer (not shown) may be formed on the outer peripheral surface of the honeycomb structure 300.

In the honeycomb structure of the present invention, the ends of the cells may not be sealed. Such a honeycomb structure can be suitably 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 present invention is not limited to a cylindrical shape, and may be an elliptical cylindrical shape.

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 fiber and / or whisker included in the adhesive paste include inorganic fiber and / or whisker 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 preferably 35 to 60%.
When the honeycomb structure manufactured using the above-mentioned honeycomb fired body is used as a filter, if the porosity is less than 35%, the honeycomb structure of the embodiment of the present invention may be immediately clogged. This is because if the porosity exceeds 60%, the strength of the honeycomb fired body is lowered and may be easily broken.

The average pore diameter of the honeycomb fired body is desirably 5 to 30 μm.
When the honeycomb structure manufactured using the above honeycomb fired body is used as a filter, if the average pore diameter is less than 5 μm, the particulates may easily clog, while the average pore diameter is 30 μm. If it exceeds, the particulates will pass through the pores, and the particulates cannot be collected and may not 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 fired body is not particularly limited, but a desirable lower limit is 31.0 / cm ² (200 / inch ² ), and a desirable upper limit is 93.0 / cm ² (600 / inch). ² ), the more desirable lower limit is 38.8 / cm ² (250 / inch ² ), and the more desirable upper limit is 77.5 / cm ² (500 / inch ² ).
Further, the thickness of the cell wall of the honeycomb fired body is not particularly limited, but is desirably 0.1 to 0.4 mm.

The main component of the constituent material of the honeycomb fired body is not limited to silicon carbide, and as other ceramic raw materials, for example, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, titanium nitride, zirconium carbide, Examples thereof include ceramic powders such as carbide ceramics such as titanium carbide, tantalum carbide, and tungsten carbide, and oxide ceramics such as alumina, zirconia, cordierite, mullite, 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. In general, the blending amount of the organic binder is desirably 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.

Although it does not specifically limit as a sealing material paste which seals a cell, What has the porosity of 30-75% of the sealing material manufactured through a post process is desirable, for example, the paste-like thing similar to a wet mixture Can be used.

The honeycomb structure may be loaded with a catalyst for purifying exhaust gas. As the catalyst to be loaded, 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 mold having substantially the same shape, and the adhesive paste may be injected between the honeycomb fired bodies.

1 is a perspective view schematically showing a honeycomb structure of the present invention. Fig. 2 (a) is a perspective view schematically showing a central honeycomb fired body constituting the honeycomb structure of the present invention, and Fig. 2 (b) is a central honeycomb fired body shown in Fig. 2 (a). It is an AA line sectional view of a body. FIG. 3 (a) is a perspective view schematically showing an outer peripheral honeycomb fired body constituting the honeycomb structure of the present invention, and FIG. 3 (b) is an outer peripheral honeycomb fired body shown in FIG. 3 (a). It is the perspective view which observed the body from the direction different from Fig.3 (a). Fig. 3 is a plan view schematically showing a cross section when the honeycomb structure of the present invention is cut perpendicularly to the longitudinal direction. Fig. 5 (a) is a perspective view schematically showing the outer peripheral honeycomb fired body constituting the honeycomb structure of the first embodiment, and Fig. 5 (b) is an outer peripheral portion shown in Fig. 5 (a). It is the perspective view which observed the honeycomb calcination object from the direction different from Drawing 5 (a). FIG. 3 is a cross-sectional view schematically showing a cross section when the honeycomb structure of the first embodiment is cut perpendicularly to the longitudinal direction. FIG. 7 (a) is a perspective view schematically showing an outer peripheral honeycomb fired body different from the outer peripheral honeycomb fired body shown in FIGS. 5 (a) and 5 (b), and FIG. 7 (b). FIG. 8 is a perspective view of the outer peripheral honeycomb fired body shown in FIG. 7A observed from a direction different from FIG. 7A. FIG. 8 is a cross-sectional view schematically showing a cross section when a honeycomb structure using the outer peripheral honeycomb fired body shown in FIGS. 7A and 7B is cut perpendicularly to the longitudinal direction. Fig.9 (a) and FIG.9 (b) are sectional drawings for demonstrating another example of the manufacturing method of the honeycomb structure of this invention.

Explanation of symbols

10, 100, 200, 300 Honeycomb structure 20, 120, 220, 320 Central honeycomb fired body 30, 130, 230, 250, 330 Peripheral honeycomb fired body 40, 140, 240, 340 Adhesive layers 21, 31, 131 Cell 22, 32, 132 Cell wall 23, 33, 133 Sealing material

Claims (4)

Columnar honeycomb fired bodies in which a large number of cells are arranged in parallel in the longitudinal direction across the cell wall are a honeycomb structure in which a plurality of cells are bound via an adhesive layer,
The plurality of honeycomb fired bodies are composed of a center-portion 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 surface of the honeycomb structure,
The honeycomb fired body according to claim 1, wherein the outer peripheral honeycomb fired body has irregularities formed on at least one of the faces in contact with the adhesive layer. 2. The honeycomb structure according to claim 1, wherein one of the surfaces on which the unevenness is formed in the outer peripheral honeycomb fired body is a surface having the smallest area among the surfaces in contact with the adhesive layer. 3. The honeycomb structure according to claim 1, wherein one of the surfaces on which the unevenness is formed in the outer peripheral honeycomb fired body is a surface in contact with another outer peripheral honeycomb fired body through the adhesive layer. body. The honeycomb structure according to any one of claims 1 to 3, wherein an area of a cross section perpendicular to the longitudinal direction of the outer peripheral honeycomb fired body is larger than an area of a cross section perpendicular to the longitudinal direction of the central honeycomb fired body.

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