WO2016039331A1

WO2016039331A1 - Method for manufacturing honeycomb structure

Info

Publication number: WO2016039331A1
Application number: PCT/JP2015/075448
Authority: WO
Inventors: 和丈尾久
Original assignee: イビデン株式会社
Priority date: 2014-09-08
Filing date: 2015-09-08
Publication date: 2016-03-17
Also published as: JP6400395B2; JP2016056048A

Abstract

Provided is a method for manufacturing a honeycomb structure such that it is possible to prevent cracks caused by contact between honeycomb units that constitute the honeycomb structure when manufacturing a honeycomb structure in which multiple honeycomb units are assembled. This method for manufacturing a honeycomb structure manufactures a honeycomb structure in which multiple honeycomb units are assembled, the honeycomb units comprising silicon carbide provided with multiple cells which are to be exhaust gas channels and porous cell partition walls that define the cells. This method for manufacturing a honeycomb structure comprises: an extrusion molding step of extrusion molding a ceramic feedstock including silicon carbide to form a honeycomb molding; a degreasing step of degreasing the honeycomb molding to form a honeycomb degreased body; a firing step of firing the honeycomb degreased body to form a monolithic honeycomb fired body; a cutting step of cutting the monolithic honeycomb fired body in a direction parallel to the longitudinal direction to form multiple honeycomb units; and an assembling step of assembling the multiple honeycomb units via adhesive layers to form a honeycomb structure. The honeycomb molding formed in the extrusion molding step has, in a cross section vertical to the longitudinal direction, cutting areas that are to be cut in the cutting step and functional areas other than the cutting areas.

Description

Manufacturing method of honeycomb structure

The present invention relates to a method for manufacturing a honeycomb structure.

Particulate matter (hereinafter also referred to as PM) is contained in exhaust gas discharged from an internal combustion engine such as a diesel engine. In recent years, it has been a problem that this PM is harmful to the environment and the human body. . Also, in the exhaust gas, CO and HC, since it is also contain toxic gas components such as NO _X, are growing concerns about influences of these toxic gas components on the environment and human body.

Therefore, as an exhaust gas purification device that collects PM in exhaust gas and purifies harmful gas components, a honeycomb structure (exhaust gas treatment body) made of a porous ceramic such as silicon carbide or cordierite, and a honeycomb structure Various exhaust gas purifying apparatuses comprising a casing for housing a body, and a holding sealing material disposed between the honeycomb structure and the casing have been proposed.

As the honeycomb structure, for example, a honeycomb structure composed of only one unit mainly using oxide-based ceramics and a plurality of units mainly using non-oxidized ceramics are assembled. Honeycomb structures and the like are known.

As a method for manufacturing such a honeycomb structure in which a plurality of honeycomb units are gathered, for example, Patent Document 1 discloses a columnar porous ceramic member in which a large number of through holes are arranged in parallel in the longitudinal direction with a partition wall therebetween. A method of manufacturing a honeycomb structure having a cylindrical shape, an elliptical cylindrical shape, or a shape similar to these, which are bundled together via layers, and combining a plurality of types of porous ceramic members via an adhesive paste There is disclosed a method for manufacturing a honeycomb structure including a ceramic block manufacturing step of manufacturing a ceramic block having a shape, an elliptical column shape, or a shape similar to these shapes.

JP 2004-154718 A

In the method for manufacturing a honeycomb structure disclosed in Patent Document 1, a plurality of types of ceramic molded bodies are fired to manufacture a porous ceramic member, and then each porous ceramic member is bound through an adhesive layer to form a honeycomb. Manufactures structures. Since the ceramic molded body is a relatively small molded body, thermal expansion and the like generated during firing are small and cracks hardly occur. For this reason, the method for manufacturing a honeycomb structure disclosed in Patent Document 1 has an advantage that a large honeycomb structure can be manufactured without generating cracks in the porous ceramic member.

However, in the method for manufacturing a honeycomb structure disclosed in Patent Document 1, cracks are unlikely to occur when the ceramic molded body is fired, but a large number of porous ceramic members are produced. When assembling, porous ceramic members may collide with each other and cracks may occur due to the impact.

The present invention has been made in view of the above problems, and an object of the present invention is to make contact between the honeycomb units constituting the honeycomb structure when manufacturing a honeycomb structure in which a plurality of honeycomb units are assembled. It is providing the manufacturing method of the honeycomb structure which can suppress that a crack generate | occur | produces by this.

In order to solve the above-mentioned problems, the present inventors have made extensive studies, and as a result, produced a monolith-type honeycomb fired body, cut the honeycomb structure in a direction parallel to the longitudinal direction, and a plurality of honeycomb units. And manufacturing the honeycomb structure by assembling the plurality of honeycomb units through the adhesive layer, thereby suppressing contact between the honeycomb units and reducing the thickness of the adhesive layer. The present invention has been completed.

That is, the method for manufacturing a honeycomb structure of the present invention includes a honeycomb in which a plurality of honeycomb units made of silicon carbide each having a plurality of cells serving as exhaust gas flow paths and porous cell partition walls defining the cells are assembled. A method for producing a structure, which includes extrusion molding a ceramic raw material containing silicon carbide to produce a honeycomb molded body, degreasing the honeycomb molded body to produce a honeycomb degreased body, and the above A firing step of firing the honeycomb degreased body to produce a monolith-type honeycomb fired body, a cutting step of cutting the monolith-type honeycomb fired body in a direction parallel to the longitudinal direction, and producing a plurality of honeycomb units; Including the assembly step of assembling the plurality of honeycomb units through an adhesive layer to produce a honeycomb structure, and producing in the extrusion step The honeycomb molded body, in vertical cross section in the longitudinal direction, and having a cutting area to be cut in the cutting step, and a function region other than the cutting region.

In the method for manufacturing a honeycomb structured body of the present invention, in the extrusion molding step, a ceramic raw material containing silicon carbide is extrusion molded. Since silicon carbide is a material having excellent heat resistance, the honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention has excellent heat resistance.

In the method for manufacturing a honeycomb structured body of the present invention, a monolith type honeycomb fired body is manufactured in the firing step.
Usually, when manufacturing a honeycomb structure, after firing a plurality of honeycomb units, the fired honeycomb units are assembled by conveying or the like. When the fired honeycomb unit is transported, the honeycomb units come into contact with each other, and the honeycomb unit may be damaged. When a honeycomb structure is manufactured using such a damaged honeycomb unit, the manufactured honeycomb structure has defects such as easy gas leakage.
On the other hand, in the method for manufacturing a honeycomb structured body of the present invention, after firing the monolith type honeycomb fired body, the fired monolith type honeycomb fired body is transported or the like.
The surface area of the monolith type honeycomb fired body is smaller than the total surface area of the plurality of honeycomb units constituting the honeycomb fired body of the same size. Accordingly, the monolith-type honeycomb fired body is less likely to come into contact with something than the plurality of honeycomb units.
That is, the monolith type honeycomb fired body is less likely to be damaged by contact with something. Therefore, in the method for manufacturing a honeycomb structure of the present invention, defects are hardly generated in the manufactured honeycomb structure.

In the method for manufacturing a honeycomb structure of the present invention, the monolith-type honeycomb fired body is cut in a direction parallel to the longitudinal direction in the cutting step.
Since the monolith type honeycomb fired body is formed by sintering silicon carbide, it is very hard and hardly deformed. Therefore, when a monolith-type honeycomb fired body is cut, a honeycomb unit that is not easily deformed and has a predetermined shape can be manufactured.

In the method for manufacturing a honeycomb structure of the present invention, a plurality of honeycomb units are assembled via an adhesive layer to produce a honeycomb structure.
In general, when honeycomb units having a distorted shape are assembled, a gap is easily generated between the honeycomb units in the manufactured honeycomb structure, which easily causes gas leakage. Therefore, when assembling honeycomb units having a distortion in shape, it is necessary to increase the thickness of the adhesive layer in order to absorb the distortion. Increasing the thickness of the adhesive layer increases the pressure loss.
On the other hand, as described above, the honeycomb unit manufactured in the cutting process is not easily deformed, so that the shape is hardly distorted. Therefore, it is difficult for gaps generated due to the distortion of the honeycomb unit to occur during assembly. Therefore, the honeycomb units can be assembled without gaps without increasing the thickness of the adhesive layer in order to absorb the strain. Furthermore, when the adhesive layer is not thickened, the pressure loss of the honeycomb structure can be reduced.
In addition, the silicon carbide sintered body is very hard but brittle. When thermal stress or the like is generated inside the monolith honeycomb structure made of silicon carbide, the monolith honeycomb structure may not withstand the thermal stress and may be damaged. However, in the case of a honeycomb structure in which a plurality of honeycomb units are assembled, the generated thermal stress and the like can be absorbed by the adhesive layer or the like, and thus the honeycomb structure is not easily damaged. Therefore, the honeycomb structure manufacturing method of the present invention can manufacture a honeycomb structure that is not easily damaged by thermal stress.

In the method for manufacturing a honeycomb structure of the present invention, in the extrusion molding step, extrusion molding is performed so that cutting cells cut in the cutting step and functional cells not cut in the cutting step are formed, and the cutting is performed. In the step, it is desirable to cut the monolith type honeycomb fired body along the cutting cells.
By forming the cut cells in the extrusion process, the honeycomb unit can be manufactured by simply cutting the cell partition walls of the cutting cells in the cutting process. That is, the monolith type honeycomb fired body can be easily cut.
Further, by cutting the cutting cell, a part of the cell partition wall remains on the cut surface of each honeycomb unit. When the honeycomb units are assembled via the adhesive layer in the assembly process, a part of the cell partition walls function as an anchor. Therefore, each honeycomb unit is firmly fixed in the manufactured honeycomb structure.

In the method for manufacturing a honeycomb structured body of the present invention, in the extrusion step, the area of the cross section perpendicular to the longitudinal direction of the cutting cell is larger than the area of the cross section perpendicular to the longitudinal direction of the functional cell. It is desirable to extrude.
When the area of the cross section perpendicular to the longitudinal direction of the cutting cell is large, when cutting the monolith-type honeycomb fired body in the cutting process, the functional cell is not damaged even if the cutting position is slightly shifted. It becomes easy to cut the cell. Therefore, defects are less likely to occur in the manufactured honeycomb structure.

In the honeycomb structure manufacturing method of the present invention, in the extrusion step, the cell density of the cutting cells arranged in the cutting region is made smaller than the cell density of the functional cells arranged in the functional region. It is desirable to extrude.
When the cell density of the cutting cells arranged in the cutting region is small, the number of cell partition walls to be cut in the cutting process can be reduced. Therefore, the monolith-type honeycomb fired body can be efficiently cut.

In the method for manufacturing a honeycomb structured body of the present invention, the functional cell includes an outer peripheral functional cell disposed on the outer periphery of the functional region and an inner functional cell disposed on the inner side of the outer peripheral functional cell, and the extrusion molding In the step, it is desirable to perform extrusion molding so that the area of the cross section perpendicular to the longitudinal direction of at least one of the peripheral function cells is smaller than the area of the cross section perpendicular to the longitudinal direction of the internal function cells.
When extrusion molding is performed in this manner, a honeycomb unit having a thick outer periphery can be manufactured. Therefore, the outer frame of the honeycomb unit has a mechanically strong structure, and has a sufficiently high strength against external impacts and the like. Further, since the volume of the outer periphery is large, the heat capacity of the honeycomb unit can be increased.

In the method for manufacturing a honeycomb structured body according to the present invention, the peripheral function cell includes a first peripheral function cell disposed at an outer peripheral portion of the honeycomb formed body and a second outer periphery disposed at a position other than the outer peripheral portion of the honeycomb formed body. In the extrusion step, the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell is smaller than the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. Extrusion is desirable.
With the above structure, the volume of the outer frame portion of the entire honeycomb structure to be manufactured increases. Therefore, the outer frame portion of the manufactured honeycomb structure has a mechanically strong structure and has a sufficiently high strength against external impacts and the like. Moreover, since the volume of the outer frame part of the whole honeycomb structure manufactured becomes large, the fall of a heat capacity can be suppressed.

In the method for manufacturing a honeycomb structured body of the present invention, in the extrusion step, the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell is the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. It is desirable to perform extrusion molding so as to be 60 to 80%.
When the area of the cross section perpendicular to the longitudinal direction of the first peripheral function cell is less than 60% of the area of the cross section perpendicular to the longitudinal direction of the internal function cell, the area of the opening of the first peripheral function cell is small. The exhaust gas flow path becomes narrow. Therefore, in the manufactured honeycomb structure, the gas passage resistance when the exhaust gas passes through the cell partition walls of the first outer peripheral functional cell is increased, and the pressure loss is increased.
When the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell exceeds 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell, the volume of the outer frame portion of the manufactured honeycomb structure is It becomes small and weak mechanically, and the heat capacity tends to decrease.

In the honeycomb structure manufacturing method of the present invention, in the extrusion step, the cross-sectional shape perpendicular to the longitudinal direction of the internal function cell is rectangular, and the cross-sectional shape perpendicular to the longitudinal direction of the first peripheral functional cell is Two corners are chamfered from a rectangle having a cross-sectional shape perpendicular to the longitudinal direction of the internal function cell, and the cell partition wall forming the first peripheral function cell faces the outside of the function region. It is desirable to extrude so that a thick wall region where the wall thickness gradually increases is formed.
The internal function cell and the first peripheral function cell having such a shape can be easily formed by extrusion. Therefore, the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell can be easily made smaller than the area of the cross section perpendicular to the longitudinal direction of the internal functional cell.

In the honeycomb structure manufacturing method of the present invention, in the extrusion step, the area of the cross section perpendicular to the longitudinal direction of the second outer peripheral functional cell is greater than the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. It is desirable to carry out extrusion molding so as to be small.
When the second outer peripheral functional cell has the above shape, the volume of the outer frame portion of the entire honeycomb unit increases. Therefore, the outer frame portion of the honeycomb unit has a mechanically strong structure and has a sufficiently high strength against external impacts and the like. Further, since the volume of the outer frame portion of the honeycomb unit is increased, it is possible to suppress a decrease in heat capacity.

In the honeycomb structure manufacturing method of the present invention, in the extrusion step, the area of the cross section perpendicular to the longitudinal direction of the second outer peripheral functional cell is equal to the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. It is desirable to perform extrusion molding so as to be 60 to 80%.
When the area of the cross section perpendicular to the longitudinal direction of the second peripheral function cell is less than 60% of the area of the cross section perpendicular to the longitudinal direction of the internal function cell, the area of the opening of the second peripheral function cell is small. The exhaust gas flow path becomes narrow. Therefore, the gas passage resistance when the exhaust gas passes through the cell partition walls of the second outer peripheral function cell increases, and the pressure loss increases.
When the area of the cross section perpendicular to the longitudinal direction of the second outer peripheral functional cell exceeds 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell, the volume of the outer frame portion of the manufactured honeycomb unit becomes small. It becomes mechanically weak and the heat capacity tends to decrease.

In the honeycomb structure manufacturing method of the present invention, in the extrusion step, the cross-sectional shape perpendicular to the longitudinal direction of the internal function cell is rectangular, and the cross-sectional shape perpendicular to the longitudinal direction of the second peripheral functional cell is From the rectangle which is the cross-sectional shape of the internal functional cell, two corners are chamfered, and the wall thickness gradually increases toward the outside of the functional region on the cell partition wall forming the second outer peripheral functional cell. It is desirable to extrude such that an increased thick wall region is formed.
The internal function cell and the second outer peripheral function cell having such a shape can be easily formed by extrusion molding. Therefore, the area of the cross section perpendicular to the longitudinal direction of the second outer peripheral function cell can be easily made smaller than the area of the cross section perpendicular to the longitudinal direction of the internal function cell.

In the method for manufacturing a honeycomb structured body of the present invention, in the extrusion molding step, it is desirable to perform extrusion molding so that the thickness of the cell partition wall of the functional cell is 0.210 mm or less.
When the thickness of the cell partition wall of the functional cell formed in the extrusion process is 0.210 mm or less, the thickness of the cell partition wall of the functional cell is sufficiently thin, so that PM is not deposited in the manufactured honeycomb structure. The pressure loss in the initial state can be sufficiently reduced. Further, an increase in pressure loss can be suppressed even when PM is deposited.
On the other hand, if the thickness of the cell partition wall of the functional cell formed in the extrusion molding process exceeds 0.210 mm, the thickness of the cell partition wall of the functional cell is too thick. The resistance when passing through the cell partition increases, and as a result, the pressure loss increases.

In the method for manufacturing a honeycomb structured body of the present invention, it is preferable to further include a sealing step for sealing one end of the cell.
The honeycomb structure manufactured in this way functions as a honeycomb filter that removes PM in the exhaust gas.

In the method for manufacturing a honeycomb structure of the present invention, it is desirable to further include an outer peripheral coat layer forming step of providing an outer peripheral coat layer on the outer periphery of the honeycomb structure.
By providing the outer peripheral coat layer, the mechanical strength of the manufactured honeycomb structure can be improved.

The method for manufacturing a honeycomb structure of the present invention preferably further includes a cutting step of cutting the outer periphery of the honeycomb structure and shaping the shape of the honeycomb structure before the outer peripheral coat layer forming step.
By cutting the outer periphery of the honeycomb structure and shaping the shape of the honeycomb structure, even if a chip or a dent is generated on the side surface of the honeycomb structure, they can be shaped.

FIGS. 1A to 1E are process diagrams schematically showing an example of a method for manufacturing a honeycomb structure of the present invention in the order of processes. Fig. 2 (a) is a perspective view schematically showing an example of a honeycomb formed body that is extrusion-molded in the method for manufacturing a honeycomb structure of the present invention. FIG. 2B is a cross-sectional view taken along the line AA in FIG. FIGS. 3-1 (a) and (b) are enlarged views schematically showing an enlarged part of the honeycomb formed body formed in the extrusion step of the method for manufacturing a honeycomb structure of the present invention. It is a schematic diagram which shows typically an example of the shape of the cross section perpendicular | vertical to the longitudinal direction of the cell for a cutting | disconnection and a functional cell. FIGS. 3-2 (c) and (d) are enlarged views schematically showing an enlarged part of the honeycomb formed body formed in the extrusion step of the manufacturing method of the honeycomb structure of the present invention. It is a schematic diagram which shows typically an example of the shape of the cross section perpendicular | vertical to the longitudinal direction of the cell for a cutting | disconnection and a functional cell. FIG. 3-3 (e) is an enlarged view schematically showing a part of the honeycomb formed body formed in the extrusion forming step of the manufacturing method of the honeycomb structure of the present invention. It is a schematic diagram which shows typically an example of the shape of a cross section perpendicular | vertical to the longitudinal direction of a cell and a functional cell. FIG. 4 is an enlarged view schematically showing an enlarged example of the honeycomb formed body in which the cell partition walls are cut regions, which is formed in the extrusion forming step in the method for manufacturing a honeycomb structured body of the present invention. FIG. 5 is an enlarged view schematically showing an example of the functional region in a cross section perpendicular to the longitudinal direction of the honeycomb formed body formed in the extrusion forming step in the method for manufacturing a honeycomb structure of the present invention. . FIG. 6 is a cross-sectional view schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the internal function cell. FIGS. 7A to 7E are cross-sectional views schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the peripheral function cell. FIGS. 8A to 8D are cross-sectional views schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the corner functional cell. FIGS. 9A and 9B are schematic views schematically showing an example of a cross-sectional shape in the vertical direction of the longitudinal direction of the honeycomb formed body that is extruded in the extrusion process of the manufacturing method of the honeycomb structure of the present invention. is there. FIG. 10 (a) is a perspective view schematically showing an example of a honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention. FIG. 10B is a cross-sectional view taken along line BB in FIG. FIGS. 11A to 11C are perspective views schematically showing a honeycomb formed body formed by extrusion molding in the method for manufacturing a honeycomb structure of Comparative Example 1. FIG.

Hereinafter, the manufacturing method of the honeycomb structure of the present invention will be specifically described. However, the present invention is not limited to the following description, and can be appropriately modified and applied without departing from the scope of the present invention.

A method for manufacturing a honeycomb structure according to the present invention includes a honeycomb structure in which a plurality of honeycomb units made of silicon carbide each having a plurality of cells serving as exhaust gas flow paths and porous cell partition walls defining the cells are assembled. A method for producing a honeycomb molded body by extruding a ceramic raw material containing silicon carbide, a degreasing step for degreasing the honeycomb molded body to produce a honeycomb degreased body, and the honeycomb degreasing process. A firing step of firing the body to produce a monolith-type honeycomb fired body, a cutting step of cutting the monolith-type honeycomb fired body in a direction parallel to a longitudinal direction to produce a plurality of honeycomb units, and the plurality of the above-mentioned The honeycomb unit is assembled through an adhesive layer, and a honeycomb structure is manufactured. Honeycomb molded body, in the vertical cross section in the longitudinal direction, and having a cutting area to be cut in the cutting step, and a function region other than the cutting region.

An outline of a method for manufacturing a honeycomb structure of the present invention will be described with reference to the drawings.
FIGS. 1A to 1E are process diagrams schematically showing an example of a method for manufacturing a honeycomb structure of the present invention in the order of processes.

When the honeycomb structure 1 manufactured by the method for manufacturing a honeycomb structure of the present invention is manufactured, first, as shown in FIG. 1 (a), a ceramic raw material containing silicon carbide is extruded and formed. 11 is performed.
Since silicon carbide is a material having excellent heat resistance, the honeycomb structure 1 manufactured through the steps described later has excellent heat resistance.

Next, as shown in FIG. 1 (b), a degreasing step for degreasing the honeycomb formed body 11 and producing the honeycomb degreased body 12 is performed in order to remove organic substances contained in the honeycomb formed body 11.

Next, as shown in FIG. 1 (c), in order to sinter silicon carbide contained in the honeycomb degreased body 12, the honeycomb degreased body 12 is fired to produce a monolith-type honeycomb fired body 13. Do.
Usually, when manufacturing a honeycomb structure, after firing a plurality of honeycomb units, the fired honeycomb units are assembled by conveying or the like. When the fired honeycomb unit is transported, the honeycomb units come into contact with each other, and the honeycomb unit may be damaged. When a honeycomb structure is manufactured using such a damaged honeycomb unit, the manufactured honeycomb structure has defects such as easy gas leakage.
On the other hand, when the honeycomb structure 1 is manufactured, after firing the monolith type honeycomb fired body 13, the fired monolith type honeycomb fired body 13 is transported or the like.
The surface area of the monolith honeycomb fired body 13 is smaller than the total surface area of the plurality of honeycomb units constituting the honeycomb fired body of the same size. Accordingly, the monolith-type honeycomb fired body 13 is less likely to come into contact with something than the plurality of honeycomb units.
That is, the monolith-type honeycomb fired body 13 is less likely to be damaged by contact with something. Therefore, when the honeycomb structure 1 is manufactured by the method for manufacturing a honeycomb structure of the present invention, the honeycomb structure 1 is unlikely to be defective.

Next, as shown in FIG. 1 (d), the monolith-type honeycomb fired body 13 is cut in a direction parallel to the longitudinal direction (the direction of the arrow in FIG. 1 (d)) to produce a plurality of honeycomb units 14. A cutting step is performed.
The monolith-type honeycomb fired body 13 is formed by sintering silicon carbide, and thus is extremely hard and hardly deformed. Therefore, when the monolith-type honeycomb fired body 13 is cut, the honeycomb unit 14 that is not easily deformed and has a predetermined shape can be manufactured.

Next, as shown in FIG. 1 (e), a collecting step is performed in which a plurality of honeycomb units 14 are gathered through the adhesive layer 15 to produce the honeycomb structure 1.
In general, when honeycomb units having a distorted shape are assembled, a gap is easily generated between the honeycomb units in the manufactured honeycomb structure, which easily causes gas leakage. Therefore, when assembling honeycomb units having a distortion in shape, it is necessary to increase the thickness of the adhesive layer in order to absorb the distortion. Increasing the thickness of the adhesive layer increases the pressure loss.
On the other hand, as described above, since the honeycomb unit 14 manufactured in the cutting process is not easily deformed, the shape is hardly distorted. Therefore, it is difficult to generate a gap caused by the distortion of the honeycomb unit 14 when assembled. Therefore, the honeycomb units 14 can be assembled without gaps without increasing the thickness of the adhesive layer 15 to absorb strain. Furthermore, when the adhesive layer 15 is not thickened, the pressure loss of the honeycomb structure 1 can be reduced.
In addition, the silicon carbide sintered body is very hard but brittle. When thermal stress or the like is generated inside the monolith honeycomb structure made of silicon carbide, the monolith honeycomb structure may not withstand the thermal stress and may be damaged. However, in the honeycomb structure 1 in which a plurality of honeycomb units 14 are assembled, the generated thermal stress and the like can be absorbed by the adhesive layer 15 and the like, and thus the honeycomb structure 1 is not easily damaged. Therefore, the honeycomb structure manufacturing method of the present invention can manufacture the honeycomb structure 1 that is not easily damaged by thermal stress.

Next, each step of the method for manufacturing a honeycomb structure of the present invention will be described in detail.
(1) Extrusion molding step (1-1) Preparation of ceramic raw material First, a ceramic raw material to be a raw material of a honeycomb fired body is prepared. The ceramic raw material can be prepared by mixing silicon carbide powder, an organic binder, a plasticizer, a lubricant, and water.
Since silicon carbide is a material having excellent heat resistance, the honeycomb structure 1 manufactured by the method for manufacturing a honeycomb structure of the present invention has excellent heat resistance.

If necessary, a pore-forming material such as balloons, which are fine hollow spheres containing oxide ceramics, spherical acrylic particles, and graphite may be added to the ceramic raw material.
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.

(1-2) Extrusion Molding Next, the ceramic raw material is extruded using a predetermined die and cut into a predetermined length to produce a honeycomb formed body.

The shape of the honeycomb formed body to be extruded in this step will be described.
Fig. 2 (a) is a perspective view schematically showing an example of a honeycomb formed body that is extrusion-molded in the method for manufacturing a honeycomb structure of the present invention. FIG. 2B is a cross-sectional view taken along the line AA in FIG.

As shown in FIGS. 2 (a) and 2 (b), a honeycomb formed body 11 as an example of a honeycomb formed body that is extrusion-molded in the method for manufacturing a honeycomb structure of the present invention includes a plurality of cells 20, And cell partition walls 30 for partition formation.
Further, as shown in FIG. 2B, the honeycomb formed body 11 has a cutting region 51 cut in the cutting step and a functional region 52 other than the cutting region 51 in a cross section perpendicular to the longitudinal direction.
In addition, the shape of the honeycomb formed body 11 produced by extrusion molding is preferably a columnar shape, and more preferably a column as shown in FIGS. 2 (a) and 2 (b).
Further, as shown in FIG. 2 (b), the cutting region 51 is formed in a straight line in the cross section perpendicular to the longitudinal direction of the honeycomb formed body 11, but the cutting region 51 is formed in the longitudinal direction of the honeycomb formed body 11. It is desirable to form a circle having a vertical cross-sectional shape so that it is divided into four equal parts in the vertical direction and four equal parts in the horizontal direction.

In the subsequent process, when the cutting process and the outer peripheral coat layer forming process are performed, the size of the monolith-type honeycomb fired body is 5 to 20% larger than the size of the finished honeycomb structure. Furthermore, it is desirable to shape the honeycomb formed body 11.

The cutting area 51 will be described. In the method for manufacturing a honeycomb structured body of the present invention, the shape of the cutting region 51 formed in the extrusion process is not particularly limited, but the cutting cell 21 cut in the cutting process and the functional cell 22 not cut are formed. You may extrude like.
FIGS. 3-1 (a) and (b), FIGS. 3-2 (c) and (d), and FIG. 3-3 (e) are formed in the extrusion process of the honeycomb structure manufacturing method of the present invention. FIG. 3 is an enlarged view schematically showing a part of the honeycomb formed body to be enlarged, and is a schematic view schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the cutting cells and functional cells to be cut. is there.
In FIGS. 3-1 (a) and (b), FIGS. 3-2 (c) and (d), and FIG. 3-3 (e), the straight line X indicates that the honeycomb formed body 11 is formed in a later step. When the monolith honeycomb fired body 13 is obtained, it is a portion to be cut in the cutting process.

As shown in FIG. 3-1 (a), the shape of the cross section perpendicular to the longitudinal direction of the cutting cell 21 formed in the extrusion process in the method for manufacturing a honeycomb structure of the present invention, and the longitudinal direction of the functional cell 22 The shape of the cross section in the vertical direction may be the same shape. In addition, these shapes may be rectangular or square.
When the cutting cell 21 and the functional cell 22 are formed in this way, the cutting region 51 and the functional region 52 are the following regions.
That is, the cutting region 51 divides the thickness of the cutting cell 21, the cell partition 30 between the cutting cells 21, and the cell partition 30 between the cutting cell 21 and the functional cell 22 into two equal parts. This is a region composed of the cell partition walls 30 on the cutting cell 21 side.
The functional area 52 is an area other than the cutting area 51.
Thus, by forming the cutting cells 21 in the extrusion molding process, the honeycomb unit 14 can be manufactured by simply cutting the cell partition walls 30 forming the cutting cells 21 in the cutting process. That is, the monolith type honeycomb fired body 13 can be easily cut.
Furthermore, by cutting the cutting cell 21, a part of the cell partition wall 30 remains on the cut surface of each honeycomb unit 14. When the honeycomb units are assembled through the adhesive layer 15 in the assembly process, a part of the cell partition walls 30 functions as an anchor. Therefore, each honeycomb unit 14 is firmly fixed in the manufactured honeycomb structure.

In the method for manufacturing a honeycomb structured body of the present invention, in the extrusion molding step, the length perpendicular to the cutting direction of the cutting cell 21 is equal to the cutting direction of the functional cell 22 as shown in FIG. It is desirable to extrude so as to be larger than the length in the vertical direction.
In FIG. 3B, the shape of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is a shape obtained by expanding the shape of the cross section perpendicular to the longitudinal direction of the functional cell 22 in the perpendicular direction to the cutting direction. .
If the shape of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is a shape enlarged in the direction perpendicular to the cutting direction, the cutting position is slightly shifted when the monolith honeycomb fired body 13 is cut in the cutting step. However, the cutting cell 21 can be easily cut without damaging the functional cell 22. Therefore, defects are less likely to occur in the manufactured honeycomb structure 1.

In the cross section perpendicular to the longitudinal direction of the honeycomb structure 1, the ratio of the length perpendicular to the cutting direction of the cutting cell 21 to the length perpendicular to the cutting direction of the functional cell 22 is determined by the cutting of the cutting cell 21. The length in the direction perpendicular to the direction: The length in the direction perpendicular to the cutting direction of the functional cell 22 is preferably 1.2: 1 to 2.5: 1.

In the method for manufacturing a honeycomb structured body of the present invention, the cell density of the cutting cells 21 arranged in the cutting region 51 is arranged in the functional region 52 as shown in FIG. It is desirable to perform extrusion molding so that the cell density of the functional cell 22 is smaller.
In FIG. 3C, the shape of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is a shape obtained by removing the cell partition wall 30 from the shape composed of two adjacent functional cells 22 and the cell partition wall 30 between them. It is.
When the cell density of the cutting cells 21 arranged in the cutting region 51 is small, the number of cell partition walls 30 to be cut in the cutting process can be reduced. Therefore, the monolith-type honeycomb fired body 13 can be efficiently cut.

The ratio between the cell density of the cutting cells 21 arranged in the cutting area 51 and the cell density of the functional cells 22 arranged in the functional area 52 is the cell density of the cutting cells 21 arranged in the cutting area 51: function It is desirable that the cell density of the functional cells 22 arranged in the region 52 is 1: 1.2 to 1: 2.5.
The cell density of the functional cells 22 arranged in the functional region 52 is desirably in the range of 15.5 to 62 cells / cm 2 (100 to 400 cpsi), and 31 to 46.5 cells / cm 2 (200 to 300 cpsi). ) Is more desirable.

In the method for manufacturing a honeycomb structure of the present invention, the area of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is equal to the longitudinal direction of the functional cell 22 in the extrusion process, as shown in FIG. It is desirable to perform extrusion molding so as to be larger than the cross-sectional area in the vertical direction.
3D, the shape of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is a shape obtained by enlarging the shape of the cross section perpendicular to the longitudinal direction of the functional cell 22 without changing the aspect ratio.
When the area of the cross section perpendicular to the longitudinal direction of the cutting cell 21 is large, the functional cell 22 may be damaged even if the cutting position is slightly shifted when the monolith honeycomb fired body 13 is cut in the cutting process. Therefore, the cutting cell 21 can be easily cut. Therefore, defects are less likely to occur in the manufactured honeycomb structure 1.
Further, with such a shape, the cell density of the cutting cells 21 arranged in the cutting region 51 can be made smaller than the cell density of the functional cells 22 arranged in the functional region 52. Therefore, the number of cell partition walls 30 to be cut in the cutting process can be reduced. Therefore, the monolith-type honeycomb fired body 13 can be efficiently cut.

In addition, the area of the cross section perpendicular to the longitudinal direction of each cell can be obtained by the following method.
First, the honeycomb structure 1 is cut in a direction perpendicular to the longitudinal direction. Next, an SEM image of a cross section perpendicular to the longitudinal direction of the honeycomb structure 1 is taken.
The photographed SEM image is binarized to identify a skeleton portion such as the cell partition wall 30 and a space portion of each cell. And the area of the part identified as the space part of each cell in a SEM image is made into the area of each cell.

In the method for manufacturing a honeycomb structure of the present invention, the thickness of the cell partition wall 30 between the cutting cell 21 and the functional cell 22 is set in the extrusion process, as shown in FIG. 3-3 (e). It is desirable to perform extrusion molding so as to be thicker than the thickness of the cell partition wall 30 that forms only the cells 22.
When extrusion molding is performed in this manner, the honeycomb unit 14 having a thick outer periphery can be manufactured. Therefore, the outer frame of the honeycomb unit 14 has a mechanically strong structure, and has a sufficiently high strength against external impacts and the like. Moreover, since the volume of the outer periphery is large, the heat capacity of the honeycomb unit 14 can be increased.

The thickness of the cell partition wall 30 between the cutting cell 21 and the functional cell 22 is preferably 1.5 to 3 times the thickness of the cell partition wall 30 forming only the functional cell 22. It is more desirable that it is double.

In the method for manufacturing a honeycomb structure of the present invention, in the extrusion molding step, it is desirable to perform extrusion molding so that the thickness of the cell partition wall 30 of the functional cell 22 is 0.210 mm or less, and 0.075 to 0.160 mm. It is more desirable to do.
When the thickness of the cell partition wall 30 of the functional cell 22 formed in the extrusion molding process is 0.210 mm or less, the thickness of the cell partition wall 30 of the functional cell 22 is sufficiently thin. It is possible to sufficiently reduce the pressure loss in the initial state where no is deposited. Further, an increase in pressure loss can be suppressed even when PM is deposited.
On the other hand, when the thickness of the cell partition wall 30 of the functional cell 22 formed in the extrusion molding process exceeds 0.210 mm, the thickness of the cell partition wall 30 of the functional cell 22 is too thick. The resistance when the exhaust gas passes through the cell partition wall 30 of the functional cell 22 increases, and as a result, the pressure loss increases.

In the method for manufacturing a honeycomb structured body of the present invention, the honeycomb formed body 11 formed in the extrusion forming process may be extruded so that the cell partition walls 30 become the cutting regions 51.
FIG. 4 is an enlarged view schematically showing an enlarged example of the honeycomb formed body in which the cell partition walls are cut regions, which is formed in the extrusion forming step in the method for manufacturing a honeycomb structured body of the present invention.

As shown in FIG. 4, in the extrusion molding step in the method for manufacturing a honeycomb structure of the present invention, the honeycomb molded body is formed such that the cutting cell partition walls 31 that are cut in the cutting step and the functional cell partition walls 32 that are not cut are formed. 11 may be extruded.
In FIG. 4, a straight line Y is a portion that is cut in the cutting step when the honeycomb formed body 11 becomes the monolith-type honeycomb fired body 13 in the subsequent step.
When the cutting cell partition wall 31 and the functional cell partition wall 32 are formed in this way, the cutting cell partition wall 31 becomes the cutting region 51 and the functional cell partition wall 32 is arranged in the functional region 52.

In FIG. 4, the thickness of the cutting cell partition wall 31 is larger than the thickness of the functional cell partition wall 32. Therefore, the monolith honeycomb fired body 13 can be cut without damaging the cells 20 arranged in the functional region 52 in the cutting step.

Next, the shape of the functional cell 22 arranged in the functional region 52 will be described in more detail with reference to the drawings.
FIG. 5 is an enlarged view schematically showing an example of the functional region in a cross section perpendicular to the longitudinal direction of the honeycomb formed body formed in the extrusion forming step in the method for manufacturing a honeycomb structure of the present invention. .
As shown in FIG. 5, the functional cells 22 of the honeycomb formed body 11 to be formed in the extrusion molding step include an outer peripheral functional cell 22 a disposed on the outer periphery 53 of the functional region 52 and an inner portion disposed on the inner side of the outer peripheral functional cell 22 a. And a functional cell 22b. Furthermore, the functional cell 22 includes a corner functional cell 22 c arranged at the corner 54 of the functional region 52.
In the present specification, the “corner portion of the functional area” is not included in the “periphery of the functional area”. That is, the corner function cell 22c is not included in the outer peripheral function cell 22a.
Further, in this specification, the “corner portion of the functional region” means a portion where two line segments intersect at right angles in the outline forming the functional region 52 in the cross section perpendicular to the longitudinal direction of the honeycomb formed body. Means the neighborhood of

In the extrusion forming step in the method for manufacturing a honeycomb structure of the present invention, as shown in FIG. 5, the shape of the formed honeycomb formed body has an area of a cross section perpendicular to the longitudinal direction of at least one peripheral function cell 22a. It is desirable to perform extrusion molding so as to be smaller than the area of the cross section perpendicular to the longitudinal direction of the internal function cell 22b.
When extrusion molding is performed in this manner, the honeycomb unit 14 having a thick outer periphery can be manufactured. Therefore, the outer frame of the honeycomb unit 14 has a mechanically strong structure, and has a sufficiently high strength against an external impact or the like. Moreover, since the volume of the outer periphery is large, the heat capacity of the honeycomb unit 14 can be increased.
In the extrusion process in the method for manufacturing a honeycomb structure of the present invention, the area of the cross section perpendicular to the longitudinal direction of all the outer peripheral functional cells 22a is larger than the area of the cross section perpendicular to the longitudinal direction of the internal functional cells 22b. Also, the extrusion molding may be performed so as to be small.

The area of the cross section perpendicular to the longitudinal direction of the outer peripheral functional cell 22a is preferably 60 to 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell 22b.
When the area of the cross section perpendicular to the longitudinal direction of the peripheral function cell 22a is less than 60% of the area of the cross section perpendicular to the longitudinal direction of the internal function cell 22b, the area of the opening of the peripheral function cell 22a becomes small. The exhaust gas flow path becomes narrower. Therefore, the gas passage resistance when the exhaust gas passes through the cell partition wall 30 of the outer peripheral function cell 22a increases, and the pressure loss increases.
When the area of the cross section perpendicular to the longitudinal direction of the outer peripheral functional cell 22a exceeds 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell 22b, the volume of the outer frame portion of the manufactured honeycomb unit 14 is It becomes small and weak mechanically, and the heat capacity tends to decrease.

The outer peripheral function cell 22a, the inner function cell 22b, and the corner function cell 22c will be described in more detail with reference to the drawings.
FIG. 6 is a cross-sectional view schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the internal function cell.
FIGS. 7A to 7E are cross-sectional views schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the peripheral function cell.
FIGS. 8A to 8D are cross-sectional views schematically showing an example of a cross-sectional shape perpendicular to the longitudinal direction of the corner functional cell.

The cross-sectional shape of the internal function cell 22b is preferably a rectangle α as shown in FIG. The rectangle α is more preferably a square.

The cross-sectional shape of the outer peripheral function cell 22a is preferably a shape in which corners are chamfered from the rectangle α which is the cross-sectional shape of the internal function cell 22b.
That is, in the extrusion molding process, two corners are chamfered from the rectangle α which is the cross-sectional shape of the internal functional cell 22b, and the cell partition wall 30 forming the outer peripheral functional cell 22a is directed to the outside of the functional region 52. It is desirable to extrude so that a thick wall region 33 with gradually increasing wall thickness is formed.
Examples of such shapes include those shown in FIGS. 7 (a) to (e).
In the present specification, “a shape in which corners are chamfered from a rectangle” means a shape in which corners of a rectangle are cut out from a rectangle by a straight line or a curve.

FIG. 7A shows a cross-sectional shape of the peripheral function cell 22a in which two adjacent corners of the rectangle α are hexagons cut off by two line segments A and B, respectively. The line segments A and B are not in direct contact with each other, and when the line segments A and B are extended, they intersect each other outside the rectangle α. Further, a part of the side of the rectangle α between the two cut corners forms one side of the hexagon.

FIG. 7B shows a cross-sectional shape of the peripheral functional cell 22a in which two adjacent corners of the rectangle α are pentagons cut off by two line segments C and D, respectively. The line segment C and the line segment D intersect at the side forming the rectangle α. The line segment C and the line segment D may intersect within the rectangle α. That is, there is no side that forms the pentagon between the two corners to be cut.

FIG. 7C is an octagon in which one of the two adjacent corners of the rectangle α is cut off by line segments E and F, and the other corner is cut off by line segments G and H. The cross-sectional shape of a certain peripheral function cell 22a is shown. The line segment E and the line segment F intersect each other inside the rectangle α. Furthermore, the line segment G and the line segment H cross each other within the rectangle α. Further, a part of the side of the rectangle α between the two cut corners forms one side of the octagon.

FIG. 7D shows a cross-sectional shape of the peripheral function cell 22a in which two adjacent corners of the rectangle α are cut off by two curves A ′ and B ′, respectively. Curves A ′ and B ′ are curves obtained by bending line segments A and B so that the corners of rectangle α are rounded. A part of the side of the rectangle α between the two cut corners forms the outline of the cross-sectional shape of the outer peripheral functional cell 22a.

FIG. 7E shows a cross-sectional shape of the peripheral function cell 22a in which two adjacent corners of the rectangle α are cut off by two curves C ′ and D ′, respectively. Curves C ′ and D ′ are curves obtained by bending the line segments C and D so that the corners of the rectangle α are rounded. The curve C ′ and the curve D ′ intersect at the side forming the rectangle α. The curve C ′ and the curve D ′ may intersect within the rectangle α.

The internal function cell 22b and the peripheral function cell 22a having such a shape can be easily formed by extrusion molding. Therefore, the area of the cross section perpendicular to the longitudinal direction of the outer peripheral functional cell 22a can be easily made smaller than the area of the cross section perpendicular to the longitudinal direction of the internal functional cell 22b.

The cross-sectional shape of the corner functional cell 22c is preferably a shape in which the corner is chamfered from the rectangle α which is the cross-sectional shape of the internal functional cell 22b. Examples of such shapes include those shown in FIGS. 8 (a) to 8 (d).

FIG. 8A shows a corner that is a heptagon in which three corners are cut out by line segments I, J, and K, respectively, except for the corner that is most inside the functional region 52 among the corners of the rectangle α. The cross-sectional shape of the partial function cell 22c is shown. The line segments I and J are not in direct contact with each other, and when the line segments I and J are extended, they intersect each other outside the rectangle α. Further, the line segments I and K are not in direct contact with each other, and when the line segments I and K are extended, they intersect each other outside the rectangle α. A part of each side of the rectangle α between the three cut corners forms one side of a heptagon that is a cross-sectional shape of the corner functional cell 22c.

FIG. 8B shows a cross-sectional shape of the corner functional cell 22c, which is a pentagon in which the corner that is the innermost of the functional region 52 among the corners of the rectangle α is cut out by the line segment L.

FIG. 8C illustrates a corner function in which three corner portions are cut out by curves I ′, J ′, and K ′, except for the corner portion that is most inside the functional region 52 among the corner portions of the rectangle α. The cross-sectional shape of the cell 22c is shown. Curves I ′, J ′, and K ′ are curves obtained by bending line segments I, J, and K so that the corners of rectangle α are rounded. A part of the side of the rectangle α between the three cut corners forms a cross-sectional outline of the corner functional cell 23c.

FIG. 8D shows a cross-sectional shape of the corner functional cell 22c in which the corner that is most inside the functional region 52 among the corners of the rectangle α is cut out by the curve L ′. The curve L ′ is a curve obtained by bending the line segment L so that the corner of the rectangle α is rounded.

So far, the outer peripheral function cell 22a, the inner function cell 22b, and the corner function cell 22c have been described by focusing on the function region 52, but the honeycomb that is extruded in the extrusion process of the manufacturing method of the honeycomb structure of the present invention. When paying attention to the entire molded body, each functional cell 22 is desirably in the shape and arrangement described below.

FIGS. 9A and 9B are schematic views schematically showing an example of a cross-sectional shape in the vertical direction of the longitudinal direction of the honeycomb formed body that is extruded in the extrusion process of the manufacturing method of the honeycomb structure of the present invention. is there.
As shown in FIG. 9 (a), in the method for manufacturing a honeycomb structured body of the present invention, in the extrusion molding step, the outer peripheral function cell 22a is arranged in the outer peripheral portion 61 of the honeycomb molded body 11. ₁ and the second outer peripheral functional cell 22a ₂ disposed in the functional region 52 other than the outer peripheral portion 61 of the honeycomb formed body 11, and the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell 22a ₁ is It is desirable to perform extrusion molding so as to be smaller than the area of the cross section perpendicular to the longitudinal direction of the internal function cell 22b.
With the above structure, the volume of the outer frame portion of the entire honeycomb structure 1 to be manufactured increases. Therefore, the outer frame portion of the honeycomb structure 1 to be manufactured has a mechanically strong structure and has a sufficiently high strength against an external impact or the like. Moreover, since the volume of the outer frame portion of the entire honeycomb structure 1 to be manufactured is increased, it is possible to suppress a decrease in heat capacity.

Further, in the method for manufacturing a honeycomb structure of the present invention, in the extrusion process, the area of the vertical cross section in the longitudinal direction of the first outer peripheral functional cell 22a ₁ is, in the longitudinal direction of the internal functional cell 22b in the vertical direction of the cross section It is desirable to perform extrusion molding so that the area is 60 to 80%.
Area vertical section in the longitudinal direction of the first outer peripheral functional cell 22a ₁ is, when the longitudinal direction of the internal functional cell 22b is less than 60% of the area of the cross section in the vertical direction, the first outer peripheral functional cell 22a ₁ of the opening The area of the part is reduced and the exhaust gas flow path is narrowed. Therefore, in the honeycomb structure manufactured, exhaust gas passage resistance when passing through the first outer peripheral function cell partition wall 30 of the cell 22a ₁ increases, the pressure loss increases.
When the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell 21a ₁ exceeds 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell 22b, the outer frame of the manufactured honeycomb structure 1 The volume of the portion is reduced, the mechanical capacity is weakened, and the heat capacity tends to decrease.

Note that the shape of the internal function cell 22b may be the shape shown in FIG. Further, the shape of the first outer peripheral function cell 22a ₁ may be the shape shown in FIGS. 7 (a) to (e).
That is, in the extrusion step, next to the cross-sectional shape is rectangular α of internal functional cell 22b, the sectional shape of the first outer peripheral functional cell 22a ₁ is, two corners of a rectangular α is a cross-sectional shape of the internal functions cell 22b is chamfered shape and become, the cell partition walls 30 which form a first outer peripheral functional cell 22a _1, that the wall thickness toward the outside of the functional area 52 is extruded as a thick wall region 33 is formed to increase gradually desirable.

The first outer peripheral functional cell 22a ₁ having such a shape can be easily formed by extrusion molding. Therefore, it can be made smaller than the area of the vertical cross section in the longitudinal direction of the first outer peripheral functional cell 22a ₁ in the longitudinal direction in the vertical direction of the cross section of the area easily internal functional cell 22b.

Further, in FIG. 9 (a), the cross-sectional shape of the second outer peripheral function cells 22a ₂ are congruent shape to the rectangular alpha. However, as shown in FIG. 9 (b), in the method for manufacturing a honeycomb structure of the present invention, in the extrusion process, the area of the vertical cross section in a second longitudinal direction of the outer peripheral functional cells 22a _2, internal functional cells You may extrusion-mold so that it may become smaller than the area of the cross section perpendicular | vertical to the longitudinal direction of 22b.
When the second outer peripheral functional cell 22a ₂ has the above shape, the volume of the outer frame portion of the entire honeycomb unit 14 manufactured through the cutting process is increased. Therefore, the outer frame portion of the honeycomb unit 14 has a mechanically strong structure and has a sufficiently high strength against external impacts and the like. Moreover, since the volume of the outer frame part of the honeycomb unit 14 is increased, it is possible to suppress a decrease in heat capacity.

In the manufacturing method of the honeycomb structure of the present invention, in the extrusion process, the area of the vertical cross section in the longitudinal direction of the second outer peripheral function cells 22a ₂ is the longitudinal direction of the internal functional cell 22b in the vertical direction of the cross section It is desirable to perform extrusion molding so that the area is 60 to 80%.
Area vertical section in the longitudinal direction of the second outer peripheral function cells 22a ₂ is the longitudinal direction of the internal functional cell 22b is less than 60% of the area of the vertical cross-section, the second outer peripheral function cells 22a ₂ of the opening The area of the part is reduced and the exhaust gas flow path is narrowed. Therefore, exhaust gas passing resistance when passing through the cell partition wall 30 of the second outer peripheral function cells 22a ₂ is increased, the pressure loss increases.
Area of the cross section perpendicular to the longitudinal direction of the second outer peripheral function cells 22a ₂ is the longitudinal direction of the internal functional cell 22b exceeds 80% of the area of the cross section in the vertical direction, the outer frame portion of the honeycomb units 14 to be manufactured The volume of the material becomes small, becomes mechanically weak, and the heat capacity tends to decrease.

Further, the shape of the second outer peripheral functional cell 22a ₂ may be the shape shown in FIGS. 7 (a) to 7 (e).
That is, in the extrusion process, the cross-sectional shape in the direction perpendicular to the longitudinal direction of the second outer peripheral function cell 22a ₂ is a shape in which two corners are chamfered from the rectangle α which is the cross-sectional shape of the internal function cell 22b. It is desirable to extrude the cell partition wall 30 forming the outer peripheral functional cell 22a _{2 so} that a thick wall region 33 whose wall thickness gradually increases toward the outside of the functional region 52 is formed.
The second outer peripheral functional cell 22a ₂ having such a shape can be easily formed by extrusion molding. Therefore, it can be made smaller than the area of the vertical cross section in the longitudinal direction of the second outer peripheral function cells 22a ₂ in the longitudinal direction in the vertical direction of the cross section of the area easily internal functional cell 22b.

(2) Drying process Next, the honeycomb molded body 11 obtained in the extrusion molding process is subjected to a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like. Use to dry. In drying the honeycomb formed body 11, a microwave dryer and a hot air dryer are used in combination, or the honeycomb formed body is dried to a certain level of moisture using a microwave dryer, and then a hot air dryer is used. It may be used to completely remove moisture in the honeycomb formed body.

(3) Degreasing Step Next, the honeycomb molded body 11 is heated at 300 to 650 ° C. for 0.5 to 3 hours to remove organic substances in the honeycomb molded body 11, thereby producing the honeycomb degreased body 12.

(4) Firing Step The honeycomb degreased body 12 is fired at 1800 to 2200 ° C. for 0.5 to 4 hours in an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere, and the monolith honeycomb fired body 13 is manufactured.

(5) Cutting process The monolith-type honeycomb fired body 13 is cut in a direction parallel to the longitudinal direction to produce a plurality of honeycomb units 14.
The position at which the monolith-type honeycomb fired body 13 is cut has already been described in the description of the above-described (1) extrusion molding step, and therefore description thereof is omitted here.
The means for cutting the monolith honeycomb fired body is not particularly limited, but can be cut using a diamond cutter or the like.

(6) Assembly step (6-1) Preparation of adhesive paste First, an adhesive paste for adhering the honeycomb unit 14 is prepared.
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.
Examples of the inorganic particles contained in the adhesive paste include carbide particles and nitride particles. Specific examples include silicon carbide particles, silicon nitride particles, and boron nitride particles. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide particles 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 fiber is desirable. The inorganic fiber may be a biosoluble fiber.
Furthermore, you may add the balloon which is a micro hollow sphere which uses an oxide type ceramic as a component, spherical acrylic particle, graphite, etc. to the said adhesive paste. 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.

(6-2) Assembly of honeycomb units The prepared adhesive paste is applied to the side surfaces of the honeycomb units to collect a plurality of honeycomb units.
Thereafter, the assembled honeycomb unit is heated to solidify the adhesive paste by heating to form the adhesive layer 15, and the cylindrical honeycomb structure 1 is manufactured.

(7) Cutting Step Next, when the subsequent outer peripheral coat layer forming step is performed, the outer periphery of the honeycomb structure 1 may be cut to shape the shape of the honeycomb structure 1.
By cutting the outer periphery of the honeycomb structure 1 to shape the shape of the honeycomb structure 1, even if a chipping or a dent is generated on the side surface of the honeycomb structure 1, they can be shaped.

(8) Outer peripheral coat layer forming step Next, if necessary, the outer peripheral coat material paste is applied to the outer periphery of the honeycomb structure 1 on the outer periphery of the honeycomb structure 1 and dried and solidified to form the outer peripheral coat layer 16. May be.
Here, the said adhesive paste can be used as an outer periphery coating material paste. Moreover, you may use the paste of a composition different from the said adhesive material paste as an outer periphery coating material paste. Note that the outer peripheral coat layer 16 is not necessarily provided, and may be provided as necessary. Further, the outer peripheral coat layer 16 may be provided after the outer periphery of the honeycomb structure 1 is cut into a predetermined shape.
By providing the outer peripheral coat layer 16, the mechanical strength of the manufactured honeycomb structure 1 can be improved.

The honeycomb structure 1 can be manufactured through the above steps.

Further, in order for the honeycomb structure 1 to function as a honeycomb catalyst for purifying exhaust gas, the catalyst may be supported on the cells 20 of the honeycomb structure 1.
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.
When these catalysts are supported, toxic exhaust gas can be purified.

The method for supporting the catalyst is not particularly limited. For example, the honeycomb unit 14 may be immersed in the catalyst-containing solution before the assembly step (6), and then the catalyst may be supported by heating.

Moreover, in order to make the honeycomb structure 1 function as a honeycomb filter that collects PM in the exhaust gas, a sealing step of sealing one end of the cell 20 may be performed.
The method for sealing one end of the cell 20 is not particularly limited. For example, after the above-described (2) drying step, a sealing material paste that becomes a sealing material in a predetermined cell 20 of the honeycomb formed body 11 The cell 20 may be sealed by filling. Here, the ceramic raw material can be used as the sealing material paste.
In addition, after the (5) cutting step, the cells 20 may be sealed by filling a predetermined cell 20 of the honeycomb unit 14 with a sealing material paste as a sealing material. Then, you may sinter sealing material paste by degreasing and baking on the same conditions as said (3) degreasing process and (4) baking process.

Next, the honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention will be described.

FIG. 10 (a) is a perspective view schematically showing an example of a honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention. FIG. 10B is a cross-sectional view taken along line BB in FIG.
A honeycomb structure shown in FIG. 10 (a) has a plurality of cells 120, one end of which is sealed with a sealing material 118, serving as an exhaust gas flow path, and a porous cell partition wall that defines the cells 120. 130 is a honeycomb filter 101 in which honeycomb units 114 including 130 are assembled via an adhesive layer 115. A peripheral coat layer 116 is formed around the honeycomb filter 101.
A case where exhaust gas passes through the honeycomb filter 101 having the above-described configuration will be described below with reference to FIG.
As shown in FIG. 10 (b), the exhaust gas discharged from the internal combustion engine and flowing into the honeycomb filter 101 (in FIG. 10 (b), the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by an arrow) is the honeycomb filter 101. Flows into one cell 120 opened in the exhaust gas inflow side end face 101 a and passes through a cell partition wall 130 that separates the cells 120. At this time, PM in the exhaust gas is collected by the cell partition wall 130 and the exhaust gas is purified. The purified exhaust gas flows out from the other cells 120 opened in the exhaust gas outflow side end face 101b and is discharged to the outside.
Thus, the honeycomb filter manufactured by the method for manufacturing a honeycomb structure of the present invention is useful as an exhaust gas treatment body for treating exhaust gas.

In such a honeycomb filter 101, the cell partition wall 130 preferably has a porosity of 40 to 65%.
When the porosity of the cell partition wall is 40 to 65%, the cell partition wall 130 can collect PM in the exhaust gas well and suppress an increase in pressure loss caused by the cell partition wall 130. Can do. Therefore, the initial pressure loss is low, and even if PM is deposited, the pressure loss is unlikely to increase.
When the porosity of the cell partition wall 130 is less than 40%, the ratio of the pores of the cell partition wall 130 is too small, so that the exhaust gas does not easily pass through the cell partition wall 130, and the pressure loss when the exhaust gas passes through the cell partition wall 130 increases. . On the other hand, when the porosity of the cell partition 130 exceeds 65%, the mechanical strength of the cell partition 130 is lowered, and cracks are likely to occur during regeneration.

In such a honeycomb filter 101, the average pore diameter of the pores contained in the cell partition wall 130 is desirably 8 to 25 μm.
In the honeycomb filter 101 having the above configuration, PM can be collected with high collection efficiency while suppressing an increase in pressure loss.
If the average pore diameter of the pores contained in the cell partition 130 is less than 8 μm, the pores are too small, and the pressure loss when the exhaust gas permeates the cell partition 130 increases. On the other hand, when the average pore diameter of the pores contained in the cell partition wall exceeds 25 μm, the pore diameter becomes too large, and the PM collection efficiency is lowered.

The porosity and average pore diameter can be measured by mercury porosimetry.

In addition, the honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention can be used as a honeycomb catalyst for purifying exhaust gas by supporting a catalyst on a cell partition wall without sealing one of the cells. it can. In such a honeycomb catalyst, the exhaust gas can be purified by the catalyst when the exhaust gas passes through the cell.

(Example)
Examples that specifically disclose modes for carrying out the present invention are shown below, but the modes for carrying out the present invention are not limited to these examples.

(Example 1)
(1) Extrusion step (1-1) Preparation of ceramic raw material 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 To the resulting mixture, 4.6% by weight of organic binder (methyl cellulose), 0.8% by weight of lubricant (Unilube manufactured by NOF Corporation), 1.3% by weight of glycerin, pore former ( Acrylic resin) 1.9 wt%, oleic acid 2.8 wt%, and water 13.2 wt% were added and mixed to prepare a ceramic raw material.

(1-2) Extrusion Molding Next, the ceramic raw material was extruded using a mold, and a honeycomb molded body was produced so that cutting cells and functional cells were formed as follows.
The honeycomb formed body was formed to be a cylinder having a bottom diameter of 145.0 mm and a length in the longitudinal direction of 150.0 mm.
The extruded honeycomb formed body includes a cutting cell and a functional cell, and the cutting cell is formed by dividing a circle having a cross-sectional shape perpendicular to the longitudinal direction of the honeycomb formed body into four equal parts in the longitudinal direction and in the lateral direction. It was made to arrange in the position which divides into 4 equally.
The cross-sectional shape of the cutting cell was a rectangle of length × width = 3.6 × 1.7 mm or 1.7 × 3.6 mm. The cross-sectional shape of the functional cell was a square having a side of 1.7 mm.
In the honeycomb formed body, the cell density of the cutting cells arranged in the cutting region was 15.5 cells / cm ² (100 cpsi). The cell density of the functional cells arranged in the functional region was 31 cells / cm ² (200 cpsi). The thickness of the cell partition wall for forming the cutting cell and the cell partition wall for forming the functional cell was 0.203 mm.

(2) Drying step Next, the honeycomb formed body was dried using a microwave dryer, thereby producing a dried body of the honeycomb formed body.

(3) Degreasing step Next, the dried honeycomb molded body was degreased at 400 ° C for 2 hours to prepare a honeycomb degreased body.

(4) Firing Step Next, the honeycomb degreased body was fired under conditions of 2200 ° C. and 2 hours and 40 minutes under an atmospheric pressure of argon atmosphere to produce a monolith type honeycomb fired body.
The monolith type honeycomb fired body had a porosity of 45% and an average pore diameter of 15 μm.

(5) Cutting Step Next, the monolith-type honeycomb fired body was cut in a direction parallel to the longitudinal direction along the cutting cells using a diamond cutter, thereby producing 16 honeycomb units.

(6) Assembly step (6-1) Preparation of adhesive paste 30% by weight of alumina fibers with an average fiber length of 20 μm, 21% by weight of silicon carbide particles with an average particle diameter of 0.6 μm, 15% by weight of silica sol, 5.6 carboxymethylcellulose % By weight and 28.4% by weight of water were mixed to prepare a heat-resistant adhesive paste.

(6-2) Aggregation of honeycomb units Adhesive paste was applied to the side surfaces of the prepared honeycomb units, and the honeycomb units were assembled into a cylindrical shape.
Thereafter, the assembled honeycomb unit was heated at 120 ° C. to heat and solidify the adhesive paste to form an adhesive layer, thereby producing a cylindrical honeycomb structure.

(7) Cutting process Next, the outer periphery of the honeycomb structure was cut to shape the shape of the honeycomb structure so that the bottom surface had a diameter of 137.2 mm.

(8) Outer peripheral coat layer forming step Next, the outer periphery of the honeycomb structure was cut to shape the shape of the honeycomb structure. Thereafter, an outer peripheral coating material paste having the same composition as the adhesive paste was applied to the outer peripheral surface of the honeycomb fired body aggregate, and the outer peripheral coating material paste was dried and solidified at 120 ° C. to form an outer peripheral coating layer.

(Comparative Example 1)
Comparative example as in Example 1 except that the above “(1-2) extrusion molding” was changed to the following “(1-2 ′) extrusion molding” and the above “(5) cutting step” was not performed. A honeycomb structure according to No. 1 was produced.

(1-2 ′) Extrusion Next, the ceramic raw material is extruded using a predetermined mold, and four honeycomb formed bodies 81a having the shape shown in FIG. 11 (a) are shown in FIG. 11 (b). Eight honeycomb formed bodies 81b and four honeycomb formed bodies 81c having the shape shown in FIG.
FIGS. 11A to 11C are perspective views schematically showing a honeycomb formed body formed by extrusion molding in the method for manufacturing a honeycomb structure of Comparative Example 1. FIG.
A honeycomb formed body 81a shown in FIG. 11A has a size of 34.3 mm × 34.3 mm × 150 mm, a cross-sectional shape perpendicular to the longitudinal direction of the cell, a square having a side of 1.7 mm, and a cell density of 31. Piece / cm ² (200 cpsi), and the thickness of the cell partition wall was 0.203 mm.
The honeycomb formed

bodies

81b and 81c shown in FIGS. 11 (b) and 11 (c) have a shape obtained by cutting a part of the honeycomb formed body 81a, and have four honeycomb formed bodies 81a, eight honeycomb formed bodies 81b, and 4 When the two honeycomb molded bodies 81c were combined, the bottom surface had a diameter of 137.2 mm and a length in the longitudinal direction of 150.0 mm.

In the method for manufacturing a honeycomb structure of Example 1, the outer periphery of the honeycomb structure is not affected even when chipping occurs on these side surfaces when carrying the honeycomb formed body, the honeycomb degreased body, and the honeycomb fired body between the steps. Since the shape of the honeycomb structure was cut and the outer peripheral coat layer was formed, it was possible to obtain a good product.
On the other hand, in the method for manufacturing a honeycomb structure of Comparative Example 1, when carrying out the honeycomb formed body, the honeycomb degreased body, and the honeycomb fired body between the respective steps, it is possible to recover when chipping occurs on these side surfaces. It was not possible and became a defective product.

DESCRIPTION OF SYMBOLS 1

Honeycomb structure

11, 81a, 81b, 81c Honeycomb molded body 12 Honeycomb defatted body 13 Monolith type honeycomb fired

body

14, 114

Honeycomb unit

15, 115 Adhesive material layer 16, 116 Outer

peripheral coat layer

20, 120 Cell 21 Cutting cell 22 functional cell 22a outer peripheral functional cell 22a ₁ first outer peripheral functional cell 22a ₂ second outer peripheral functional cell 22b internal functional cell 22c corner

functional cell

30, 130 cell partition 31 cutting cell partition 32 functional cell partition 33 thick wall region 51 cutting Area 52 Functional area 53 Perimeter of functional area 54 Corner 61 of functional area Perimeter 101 Honeycomb filter 118 Sealing material

Claims

A method for manufacturing a honeycomb structure in which a plurality of honeycomb units made of silicon carbide having a plurality of cells serving as exhaust gas flow paths and a porous cell partition wall defining the cells are assembled,
Extruding a ceramic raw material containing silicon carbide to produce a honeycomb formed body; and
Degreasing the honeycomb formed body and producing a honeycomb degreased body; and
A firing step of firing the honeycomb degreased body to produce a monolith-type honeycomb fired body,
Cutting the monolith-type honeycomb fired body in a direction parallel to the longitudinal direction to produce a plurality of honeycomb units;
An assembly step of assembling the plurality of honeycomb units via an adhesive layer to produce a honeycomb structure,
The honeycomb molded body produced in the extrusion molding step has a cutting region cut in the cutting step and a functional region other than the cutting region in a cross section perpendicular to the longitudinal direction. Manufacturing method of structure.
In the extrusion molding step, extrusion molding is performed so that a cutting cell cut in the cutting step and a functional cell not cut in the cutting step are formed,
The method for manufacturing a honeycomb structure according to claim 1, wherein in the cutting step, the monolith-type honeycomb fired body is cut along the cutting cells.
3. The honeycomb according to claim 2, wherein in the extrusion molding step, extrusion is performed such that an area of a cross section perpendicular to the longitudinal direction of the cutting cell is larger than an area of a cross section perpendicular to the longitudinal direction of the functional cell. Manufacturing method of structure.
4. The extrusion molding process according to claim 2, wherein in the extrusion step, extrusion molding is performed so that a cell density of the cutting cells arranged in the cutting region is smaller than a cell density of the functional cells arranged in the functional region. Method for manufacturing the honeycomb structure.
The functional cell includes an outer peripheral functional cell disposed on the outer periphery of the functional area, and an inner functional cell disposed on the inner side of the outer peripheral functional cell,
In the extrusion molding step, extrusion molding is performed such that an area of a cross section perpendicular to the longitudinal direction of at least one of the outer peripheral functional cells is smaller than an area of a cross section perpendicular to the longitudinal direction of the internal functional cells. 5. A method for manufacturing a honeycomb structure according to any one of 2 to 4.
The outer peripheral functional cell includes a first outer peripheral functional cell disposed at an outer peripheral portion of the honeycomb molded body and a second outer peripheral functional cell disposed at a position other than the outer peripheral portion of the honeycomb molded body, The honeycomb structure according to claim 5, wherein the honeycomb structure is extruded so that an area of a cross section perpendicular to a longitudinal direction of the first outer peripheral functional cell is smaller than an area of a cross section perpendicular to the longitudinal direction of the internal functional cell. Body manufacturing method.
In the extrusion molding step, extrusion is performed such that the area of the cross section perpendicular to the longitudinal direction of the first outer peripheral functional cell is 60 to 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. The method for manufacturing a honeycomb structured body according to claim 6.
In the extrusion molding step, the cross-sectional shape perpendicular to the longitudinal direction of the internal functional cell is rectangular, and the cross-sectional shape perpendicular to the longitudinal direction of the first outer peripheral functional cell is perpendicular to the longitudinal direction of the internal functional cell. A thick wall region in which two corners are chamfered from a rectangle having a cross-sectional shape, and the wall thickness gradually increases toward the outside of the functional region on the cell partition wall forming the first outer peripheral functional cell. The method for manufacturing a honeycomb structured body according to claim 6 or 7, wherein the honeycomb structure is extruded so as to be formed.
7. The extrusion molding step is performed such that an area of a cross section perpendicular to the longitudinal direction of the second outer peripheral functional cell is smaller than an area of a cross section perpendicular to the longitudinal direction of the internal functional cell. 9. A method for manufacturing a honeycomb structure according to any one of 8 to 8.
In the extrusion molding step, extrusion is performed such that the area of the cross section perpendicular to the longitudinal direction of the second outer peripheral functional cell is 60 to 80% of the area of the cross section perpendicular to the longitudinal direction of the internal functional cell. The method for manufacturing a honeycomb structured body according to any one of claims 6 to 9.
In the extrusion molding step, a cross-sectional shape perpendicular to the longitudinal direction of the internal function cell is a rectangle, and a cross-sectional shape perpendicular to the longitudinal direction of the second outer peripheral function cell is a rectangle that is a cross-sectional shape of the internal function cell. The two corners are chamfered to form a thick wall region in which the wall thickness gradually increases toward the outside of the functional region on the cell partition wall forming the second outer peripheral functional cell. The method for manufacturing a honeycomb structured body according to any one of claims 6 to 10, wherein the forming is performed.
The method for manufacturing a honeycomb structured body according to any one of claims 2 to 11, wherein in the extrusion molding step, extrusion molding is performed so that a thickness of a cell partition wall of the functional cell is 0.210 mm or less.
The method for manufacturing a honeycomb structured body according to any one of claims 1 to 12, further comprising a sealing step of sealing one end of the cell.
The method for manufacturing a honeycomb structure according to any one of claims 1 to 12, further comprising an outer peripheral coat layer forming step of providing an outer peripheral coat layer on an outer periphery of the honeycomb structure.
The method for manufacturing a honeycomb structure according to claim 14, further comprising a cutting step of cutting an outer periphery of the honeycomb structure to shape a shape of the honeycomb structure before the outer peripheral coat layer forming step.