JP2008273810A - Method for manufacturing honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a honeycomb structure which includes a binding process for preparing a honeycomb assembly by binding together a plurality of honeycomb sintered compacts through an adhesive layer and by which the honeycomb structure can be manufactured by preventing the generation of warps in each honeycomb sintered compact in a firing process. <P>SOLUTION: The honeycomb sintered compact is manufactured by mounting a honeycomb formed body 120 on spacers 12 arranged on a bottom plate 11 of a firing jig 10 and firing the honeycomb formed body. In a firing process, the spacers are arranged at least at two parts so that the spacers put the gravity center G of the honeycomb formed body 120 between them in the longitudinal direction when the honeycomb formed body mounted on the spacers is viewed in a planar view, and further, the spacers are arranged at respective central points L existing between the gravity center when the honeycomb formed body is viewed in the planar view and gravity centers of the both end surfaces in the longitudinal direction of the honeycomb formed body so that both of an area on the gravity center side and an area on the end surface side are included. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In recent years, it has become a problem that particulates such as soot in exhaust gas discharged from internal combustion engines such as vehicles such as buses and trucks and construction machinery cause harm to the environment and the human body.
In view of this, various particulate filters have been proposed that collect particulates in exhaust gas and purify the exhaust gas by using a honeycomb structure made of porous ceramic. There is also known a honeycomb structure that modifies nitrogen oxides and the like in exhaust gas by bringing the supported catalyst into contact with exhaust gas.

As such a honeycomb structure, a prism-shaped honeycomb fired body manufactured by performing extrusion molding, degreasing, firing, or the like on a mixture containing a ceramic material such as silicon carbide is a sealing material layer (adhesive layer). ) Is used to form a cylindrical honeycomb structure that is bundled through the two.

The honeycomb fired body can be manufactured, for example, by the following method.
First, a raw material composition is prepared by mixing a ceramic material such as silicon carbide, a binder, a dispersion medium liquid, and the like, and after continuously extruding the raw material composition, the extruded molded body has a predetermined length. The prism-shaped honeycomb molded body is manufactured by cutting into pieces.
Next, the obtained honeycomb formed body was dried using microwave drying or hot air drying, and then a predetermined cell was plugged, and either end of the cell was sealed. Then, a degreasing process is performed.
Finally, a firing step for firing the honeycomb formed body is performed. A honeycomb fired body can be manufactured through the above steps.

Among the above steps, the firing step is a step of producing a honeycomb fired body by heating the honeycomb formed body produced by an extrusion molding process and having organic substances burned and removed by a degreasing process to heat and sinter ceramic powder. However, in this firing step, the honeycomb formed body was placed on the bottom plate of the carbon firing jig and fired.
However, since the honeycomb formed body containing silicon carbide as the ceramic material contains about 3% SiO ₂ in the silicon carbide powder due to the manufacturing conditions, in this firing step, the honeycomb formed body is made of SiO _2. Is sublimated and released, and part of it becomes SiO gas, and this SiO gas reacts with the carbon constituting the firing jig to produce SiC, which is carbonized on the bottom plate of the firing jig. In some cases, coarse silicon particles were formed.
The firing jig is a member that is repeatedly used. In the state where coarse particles of silicon carbide are formed on the bottom plate of the firing jig, the honeycomb molded body is placed on the bottom plate of the firing jig to perform the firing step. However, the surface of the honeycomb molded body is easily damaged, and the resulting honeycomb fired body has chipping and pinholes, which may cause a decrease in strength of the honeycomb fired body.
Furthermore, when such coarse particles of silicon carbide are formed, there is a problem that it is difficult to repeatedly use the firing jig.

Patent Documents 1 and 2 disclose a method for firing a silicon carbide formed body (honeycomb formed body) in which a space is provided between the bottom plate of the firing jig and the silicon carbide formed body for firing.
FIG. 8 is a cross-sectional view schematically showing a method of performing a firing step by placing a spacer on the bottom plate of a firing jig and placing a honeycomb formed body on the spacer.

In Patent Document 1, as shown in FIG. 8, a spacer 12 made of a ceramic member such as carbon is disposed on a bottom plate 11 of a firing jig 10, and a honeycomb formed body 120 is placed on the spacer 12 to perform a firing process. A space corresponding to the thickness of the spacer 12 is provided between the bottom plate 11 of the firing jig 10 and the honeycomb formed body 120.

According to Patent Document 1, by providing a space between the bottom plate 11 of the firing jig 10 and the honeycomb formed body 120 in this way and performing the firing step, coarse silicon carbide is formed on the bottom plate 11 of the firing jig 10. It is said that it is possible to prevent the formation of particles and the generation of chips and pinholes in the manufactured honeycomb fired body.

In Patent Document 2, a firing jig provided with a protrusion is disclosed. When a silicon carbide formed body (honeycomb formed body) is placed on the protrusion of the firing jig, a space corresponding to the thickness of the protrusion is provided between the bottom plate of the firing jig and the honeycomb formed body. Can do.
Therefore, by performing the firing step using the firing jig disclosed in Patent Document 2, it is possible to prevent the formation of coarse silicon carbide particles on the bottom plate of the firing jig. It is said that chipping and pinholes can be prevented.

JP 2001-220240 A JP 2001-72472 A

However, as shown in FIG. 8, when the firing process is performed with a space provided between the honeycomb formed body and the bottom plate of the firing jig, the manufactured honeycomb fired body may be warped.

FIG. 9 is a cross-sectional view schematically showing how the vicinity of the center of gravity of the honeycomb formed body placed on the spacer sinks and warps.
When the honeycomb formed body 120 is placed on the spacer 12 disposed on the bottom plate 11 of the firing jig 10 and the firing process is performed, the vicinity of the center of gravity G of the honeycomb formed body 120 sinks as shown in FIG. Warpage may occur in the direction (indicated by the arrow b in FIG. 9), and warpage may occur in the honeycomb fired body manufactured by firing the honeycomb formed body in such a state. It was.
In particular, when the length of the honeycomb formed body in the longitudinal direction is 330 mm (13 inches) or more, warpage frequently occurs in the direction in which the vicinity of the center of gravity G sinks.

If a honeycomb structure is manufactured by binding a plurality of warped honeycomb fired bodies, the honeycomb fired bodies may come into contact with each other during the binding step and are difficult to manufacture. There was a problem of becoming.

The present invention has been made to solve such a problem, and a method for manufacturing a honeycomb structure capable of manufacturing a honeycomb structure while preventing the honeycomb fired body from warping in the firing step. The purpose is to provide.

The present inventors have studied a firing method that can prevent the warpage of the honeycomb fired body and produce the honeycomb fired body.
First, the present inventors examined the cause of warping in the direction in which the vicinity of the center of gravity of the honeycomb formed body sinks, and a force is applied in the direction in which the honeycomb formed body sinks with respect to the center of gravity of the honeycomb formed body due to its own weight. It was predicted that this was the cause of warping.
Therefore, in addition to the two spacers shown in FIG. 9, a spacer is also arranged directly below the center of gravity of the honeycomb formed body, so that the vicinity of the center of gravity of the honeycomb formed body sinks during the firing process. Tried to prevent the occurrence of.

FIG. 10 is a partially cutaway perspective view schematically showing an example of a method of placing a honeycomb molded body in a firing jig by arranging a spacer immediately below the center of gravity of the honeycomb molded body in the firing step.
In FIG. 10, a part of the side wall member of the firing jig is omitted so that it is easy to grasp the mounting state of the honeycomb formed body.

Usually, the shape of the firing jig 10 is designed such that the length of one side of the bottom plate 11 of the firing jig 10 is slightly longer than the longitudinal length of the honeycomb formed body 120 to be placed. ing.
Therefore, when the plurality of honeycomb molded bodies 120 are placed on the spacers 12 arranged in the firing jig 10 so that the longitudinal directions thereof are parallel to each other as shown in FIG. Is positioned in the vicinity of the center line M of the bottom plate 11 of the firing jig 10.

As shown in FIG. 10, the present inventors place a honeycomb formed body 120 on the three spacers 12 and perform the firing step, thereby causing warpage in the direction in which the center of gravity of the honeycomb formed body sinks. I was able to prevent that. However, conversely, some of the honeycomb fired bodies manufactured by performing the firing process by this method have warped in the direction of raising the vicinity of the center of gravity.
A honeycomb fired body in which such warpage has occurred is also unsuitable for manufacturing a honeycomb structure, and it has been a problem that warpage occurs in the direction in which the vicinity of the center of gravity rises.

For this reason, the present inventors have examined the cause of warping in the direction in which the vicinity of the center of gravity is lifted. Then, it has been found that when the firing jig is repeatedly used, the bottom plate of the firing jig may be warped so as to be raised in a dome shape with the vicinity of the center of the bottom plate of the firing jig as a vertex.

FIG. 11 is a cross-sectional view schematically showing a state where the vicinity of the center of gravity of the honeycomb formed body placed on the spacer is lifted and warped.
As shown in FIG. 11, when the vicinity of the center of the bottom plate 11 of the firing jig 10 is warped in the lifting direction, the lifting direction is also raised in the central spacer 12 arranged along the center line of the bottom surface of the firing jig 10. Power is added to.
From this, it is estimated that an upward force (indicated by an arrow c in FIG. 11) is applied directly below the center of gravity G of the honeycomb formed body 120, and this force is near the center of gravity G of the honeycomb formed body 120. It was expected to cause warping in the lifting direction.

As described above, the present inventors diligently investigated the cause of warpage of a honeycomb fired body produced by a conventionally known method, and in the course of the examination, honeycomb firing was also performed by warping of the firing jig. As a result of discovering that warping occurs in the body and conducting further studies based on this discovery, the present invention was completed.

That is, the method for manufacturing a honeycomb fired body according to the first aspect of the present invention includes a forming step of manufacturing a columnar honeycomb formed body in which a large number of cells are arranged in parallel in the longitudinal direction with a cell wall therebetween,
A firing step of producing the honeycomb fired body by placing the honeycomb formed body on a spacer disposed on a bottom plate of a firing jig and performing a firing treatment;
A honeycomb structure manufacturing method including a binding step of manufacturing a honeycomb aggregate by binding a plurality of the honeycomb fired bodies through an adhesive layer,
In the firing step, the spacers are disposed in at least two places so as to sandwich the center of gravity of the honeycomb molded body in the longitudinal direction when the honeycomb molded body placed on the spacer is viewed in plan view. And,
The spacer is a region on the center of gravity side of each center point existing between the center of gravity when the honeycomb formed body is viewed in plan and the center of gravity of both end faces in the longitudinal direction of the honeycomb formed body, and the end surface side. It is arranged to include both of the regions.

According to the first aspect of the present invention, in the firing step, the spacers are arranged in at least two places so as to sandwich the center of gravity of the honeycomb formed body in the longitudinal direction.
When the spacers are arranged in this way, since the spacer is not arranged near the center line of the bottom plate of the firing jig, that is, immediately below the center of gravity of the honeycomb formed body, the vicinity of the center of the bottom plate of the firing jig is raised. Even when warped, the force applied in the direction of lifting the honeycomb formed body through the spacer is reduced. Therefore, the warp generated in the honeycomb fired body along the direction in which the bottom plate of the firing jig warps can be reduced.
Therefore, even when the firing jig is repeatedly used, a honeycomb fired body with a small warpage can be produced.

In the firing step, the spacer is a region on the center of gravity side and a region on the end surface side with respect to each midpoint existing between the center of gravity when the honeycomb formed body is viewed in plan and the center of gravity of both end faces in the longitudinal direction of the honeycomb formed body. Are arranged to include both.

In the firing process, a force to warp in the direction of sinking due to its own weight is applied to the vicinity of the center of gravity of the honeycomb formed body, but the fulcrum of this force is the side of the spacer closest to the center of gravity of the honeycomb formed body it is conceivable that. Therefore, when the spacer is arranged at the position defined in the present invention, the distance between the fulcrum of force and the center of gravity of the honeycomb formed body becomes shorter than the distance between the midpoint and the center of gravity of the honeycomb formed body. The force applied near the center of gravity of the body can be reduced.
Further, a force to warp in the direction of sinking due to its own weight is also applied near the end face of the honeycomb formed body, and the fulcrum of this force is considered to be the side closest to the end face of the honeycomb formed body among the spacers. . Therefore, when the spacer is disposed at the position defined in the present invention, the distance between the fulcrum of force and the end face of the honeycomb formed body becomes shorter than the distance between the midpoint and the end face. The force applied near the end face can be reduced.
Thus, since both the force applied to the vicinity of the center of gravity and the vicinity of the end face of the honeycomb formed body can be reduced, a honeycomb fired body having a small warp can be manufactured.

In the method for manufacturing a honeycomb structured body according to claim 1, since a honeycomb fired body having a small warpage can be produced in the firing step, a plurality of honeycomb fired bodies are bound to produce a honeycomb structured body. At this time, the honeycomb fired bodies are not brought into contact with each other and chipped, and the honeycomb structured body can be manufactured with a high yield.

In a second aspect of the present invention, the distance between the two spacers sandwiching the center of gravity is 25 to 45% of the length in the longitudinal direction of the honeycomb fired body.
According to the invention described in claim 2, by setting the distance between the two spacers in such a range, the effect applied to the direction in which the honeycomb formed body sinks due to its own weight is reduced, and the bottom plate of the firing jig The effect of reducing the warpage generated in the honeycomb fired body along the warping direction can be more effectively exhibited. Therefore, a honeycomb fired body with less warpage can be manufactured.

In the firing step of the invention according to claim 3, the spacer is disposed at a position overlapping with each of the two midpoints when the honeycomb formed body placed on the spacer is viewed in plan view. Has been.
Therefore, the spacer can be arranged so as to include both the region on the center of gravity side and the region on the end face side of the honeycomb fired body with respect to one midpoint with only one spacer. Therefore, a honeycomb fired body with small warpage can be easily manufactured.

In the invention according to claim 4, the length in the longitudinal direction of the spacer overlapping the midpoint is 20 to 50 mm.

According to the invention described in claim 4, since the length of the spacer in the longitudinal direction of the honeycomb formed body is 20 mm or more, the distance between the side closest to the center of gravity of the spacer and the center of gravity of the honeycomb formed body, and The distance between the side closest to the end face of the spacer and the end face of the honeycomb formed body becomes shorter, and the force applied to the vicinity of the center of gravity and the end face of the honeycomb formed body can be further reduced. Therefore, a honeycomb fired body with less warpage can be manufactured.
Further, in the region where the spacer and the honeycomb formed body are in contact, firing may be insufficient. If the firing is insufficient, the strength of the honeycomb fired body is reduced. Since the length of the spacer in the longitudinal direction of the honeycomb formed body is 50 mm or less, the area of the region where the spacer and the honeycomb formed body are in contact with each other can be reduced to reduce the area of the region where firing is insufficient. Therefore, a honeycomb fired body with high strength can be produced.

In the invention according to claim 5, in the firing step, when the honeycomb formed body placed on the spacer is viewed in plan, the spacers are arranged so that each midpoint is sandwiched between at least two spacers. A center-of-gravity side spacer is disposed in a region on the center of gravity side of the honeycomb molded body from each midpoint, and an end surface side spacer is disposed in a region on the end surface side of each honeycomb molded body from each midpoint.

According to the fifth aspect of the present invention, since the spacers are arranged in both the center-of-gravity side region and the end surface side region of the honeycomb molded body with respect to one midpoint, a honeycomb fired body having a small warpage is manufactured. be able to.
Furthermore, since the area of the area where the honeycomb formed body and the spacer are in contact with each other can be reduced to reduce the area of the area where firing is insufficient, a honeycomb fired body with high strength can be manufactured.
Further, in the region where the honeycomb formed body and the spacer are in contact, sintering of the honeycomb formed body is difficult to proceed, and the surface of the fired honeycomb fired body tends to be rough (becomes uneven). According to the invention described in claim 5, since the firing is performed sufficiently sufficiently, it is possible to produce a honeycomb fired body in which the surface of the region where the spacer is in contact is not rough.

In a sixth aspect of the invention, the distance between the position closest to the center of gravity of the end face of the end face side spacer and the position of the center of gravity side spacer closest to the center of gravity is 30 to 50 mm. In the invention according to claim 7, the distance between the position closest to the center of gravity of the end face of the end face side spacer and the position closest to the center of gravity of the center of gravity side spacer is the longitudinal direction of the honeycomb fired body. 9-16% of the length.
According to the invention of claim 6 or 7, a honeycomb fired body with less warpage can be produced.

In invention of Claim 8, the length in the said longitudinal direction of the said end surface side spacer and the said gravity center side spacer is 5-10 mm.
If the length of the spacer in the longitudinal direction is too small, the position of the honeycomb formed body tends to shift when the honeycomb formed body is placed on the spacer of the firing jig. According to the invention of claim 8, the spacer Since the length in the longitudinal direction is 5 mm or more, it is possible to prevent the honeycomb formed body from being displaced.
Furthermore, since the length of the spacer in the longitudinal direction is 10 mm or less, the area of the region where the honeycomb formed body and the spacer are in contact can be extremely reduced. Therefore, it is possible to produce a honeycomb fired body having high strength and having a rough surface (not in an uneven state) in a region where the spacer is in contact.

In the invention according to claim 9, in the firing step, when the honeycomb molded body placed on the spacer is viewed in plan, the spacer passes through the center of gravity of the honeycomb molded body and extends in the longitudinal direction. It is arranged at a position that is line symmetric with respect to a vertical straight line.
According to the ninth aspect of the invention, the force applied to the vicinity of the center of gravity and the vicinity of the end faces on both sides of the honeycomb formed body can be dispersed in a balanced manner. Therefore, a honeycomb fired body with less warpage and higher dimensional accuracy can be manufactured.

In a tenth aspect of the present invention, the length of the honeycomb formed body in the longitudinal direction is 305 mm or more.
According to the invention described in claim 10, even when the length of the honeycomb formed body is long, a honeycomb fired body with low warpage and high strength can be manufactured, and the honeycomb structure can be manufactured with high yield. .

In the invention according to claim 11, the honeycomb formed body is manufactured by forming a raw material composition containing at least silicon carbide powder and a binder.
According to the eleventh aspect of the present invention, even when the honeycomb formed body containing silicon carbide is placed and the firing process is performed, the honeycomb formed body is placed on the spacer and the firing process is performed. Further, it is possible to prevent the formation of coarse silicon carbide particles on the bottom plate of the firing jig, and to produce a honeycomb fired body having high strength.

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of the present invention will be described.
In the first embodiment, it is assumed that the honeycomb fired body shown in FIGS. 2A and 2B and the honeycomb structure shown in FIG. 1 are manufactured.

FIG. 1 is a perspective view schematically showing an example of a honeycomb structure, FIG. 2 (a) is a perspective view schematically showing a honeycomb fired body constituting the honeycomb structure, and FIG. It is the AA sectional view taken on the line.

In the honeycomb structure 100, as shown in FIG. 1, a plurality of honeycomb fired bodies 110 are bound together via an adhesive layer 101 to form a ceramic block 103, and a coat layer 102 is formed on the outer periphery of the ceramic block 103. Has been.
Further, as shown in FIG. 2A, the honeycomb fired body 110 has a plurality of cells 111 arranged in parallel in the longitudinal direction (the direction of the arrow a in FIG. 2A), and the cell walls that separate the cells 111 from each other. 113 functions as a filter.
In the present specification, the end face of the honeycomb fired body refers to the face where the cells are exposed among the faces forming the outer shape of the honeycomb fired body, and the face other than the end face is referred to as a side face.

That is, as shown in FIG. 2B, the cell 111 formed in the honeycomb fired body 110 is sealed by either the exhaust gas inflow side or the outflow side end portion with the sealing material 112, The exhaust gas flowing into the cell 111 always passes through the cell walls 113 separating the cells 111 and then flows out from the other cells 111. When the exhaust gas passes through the cell walls 113, the particulates are transferred to the cell walls 113. Captured at the part, the exhaust gas is purified.

Here, first, a method for placing the honeycomb formed body in the firing jig in the degreasing step and the firing step will be described in detail, and then all the manufacturing steps of the method for manufacturing the honeycomb structure of the present invention will be described in the order of steps. To do.

FIG. 3A is a partially cutaway perspective view schematically showing a method of placing the honeycomb formed body in the firing jig in the first embodiment of the present invention, and FIG. It is a top view of the part shown by B in (a).
In FIG. 3 (a), a part of the side wall member of the firing jig is omitted so as to easily grasp the mounting state of the honeycomb formed body.
FIG. 3 (b) shows a view rotated 90 degrees with respect to FIG. 3 (a) so that the longitudinal direction of the honeycomb formed body is lateral to the paper surface.

The firing jig 10 shown in FIG. 3 (a) is made of carbon and has a box shape with an open upper surface. The box shape is formed from four sides of the bottom plate 11 and the bottom plate 11 each having a rectangular plate shape. The side wall member 13 is erected.
The dimensions of the firing jig are designed so that the length of the short side of the bottom plate 11 is slightly longer than the length of the honeycomb molded body 120 in the longitudinal direction.
On the bottom plate 11, two spacers 12 for placing the honeycomb formed body 120 are arranged at positions that are line-symmetric with respect to the center line M passing through the midpoint of the short side of the bottom plate 11. Yes.

The spacer 12 is made of carbon felt made by combining carbon fibers into a cloth shape, the thickness thereof is 2.0 to 5.0 mm, the length of the short side is 20 to 50 mm, and the length of the long side is fired. The length is slightly shorter than the length of the long side of the bottom plate 11 of the jig 10 for use.
In the firing step in the present embodiment, two spacers 12 are arranged on the bottom plate 11 and the honeycomb formed body 120 is placed so as to have a predetermined positional relationship with the two spacers 12.
This predetermined positional relationship will be described below.

FIG. 3B is a plan view of a portion indicated by B in FIG. In this plan view, considering the points indicating the positions of the center of gravity of the left side surface 125 and the right end surface 126 of the honeycomb molded body 120, the honeycomb molded body 120 has a prismatic shape with substantially square end faces. The left end surface gravity center LG of the body 120 is the midpoint of the line segment indicating the left end surface 125, and the right end surface gravity center RG is the midpoint of the line segment indicating the right end surface 126.
The midpoints between the left end surface center of gravity LG, the right end surface center of gravity RG, and the center of gravity G of the honeycomb formed body 120 thus defined are a left midpoint L and a right midpoint R, respectively.

In the present embodiment, when the honeycomb formed body 120 placed on the spacer 12 is viewed in a plan view as shown in FIG. 3B, the left midpoint L and the right midpoint R overlap with the spacer 12. The honeycomb formed body 120 is placed on the two spacers 12.
When the spacers overlap each of the two midpoints in this way, both the center point L and the center point R include both the region on the center of gravity side and the region on the end surface side of the honeycomb formed body 120. Thus, the spacer is arranged.
Further, in the present embodiment, the honeycomb molded body 120 and the two spacers 12 are arranged so that the spacer 12 is axisymmetric with respect to a straight line M passing through the center of gravity G and perpendicular to the longitudinal direction of the honeycomb molded body 120. Defines the positional relationship.

Further, in the present embodiment, in the plan view shown in FIG. 3B, the two spacers 12 and the honeycomb molded body 120 and the two are formed so that the center of gravity G of the honeycomb molded body 120 is sandwiched in the longitudinal direction of the honeycomb molded body 120. The positional relationship of the spacers 12 is determined.

In the present embodiment, the length of the spacer 12 in the longitudinal direction of the honeycomb formed body 120 is the length indicated by W in FIG. 3B, and this length W is equal to the length of the short side of the spacer. 20-50 mm.
Hereinafter, this length W is referred to as the length W in the longitudinal direction of the spacer or the length W in this specification.

Further, in the present embodiment, the distance between the two spacers 12 is a distance indicated by E in FIG. 3B and is 25 to 45% of the length in the longitudinal direction of the honeycomb formed body 120.
This distance E is a position on a straight line passing through the center L of the left end surface LG and the center of gravity G of the honeycomb formed body, and is closest to the center of gravity G of the spacer 12 that overlaps the midpoint L. It is determined as a ratio (%) of the distance E between the position 14R closest to the center of gravity G of the spacer 12 that overlaps the midpoint R and the position E on the straight line passing through the center of gravity G of the formed body. .
Hereinafter, this distance E (%) is referred to as a distance E between spacers or a distance E in this specification.

Next, all manufacturing steps of the manufacturing method of the honeycomb structure according to the first embodiment of the present invention, including the degreasing step and the firing step performed by placing the honeycomb formed body in the firing jig in this manner. These will be described in the order of steps.

First, a raw material composition containing silicon carbide powder having different average particle diameters and an organic binder is dry-mixed to prepare a mixed powder, and a liquid plasticizer, a lubricant and water are mixed to prepare a mixed liquid. Subsequently, the mixed powder and the mixed liquid are mixed using a wet mixer to prepare a wet mixture for manufacturing a molded body.

Next, a molding process is performed in which the wet mixture is put into an extruder and extruded.
Then, the long honeycomb molded body obtained by extrusion molding is cut using a cutting device, thereby producing the prism-shaped honeycomb molded body shown in FIG.
In the present embodiment, the honeycomb molded body is cut so that the length in the longitudinal direction is 305 mm or more.
Thereafter, the honeycomb formed body is dried using a dryer in which microwaves and hot air are combined.

Next, a predetermined amount of a sealing material paste serving as a sealing material is filled in the outlet side end portion of the inlet side cell group and the inlet side end portion of the outlet side cell group, and the cells are sealed. When sealing the cells, a sealing mask is applied to the end face of the honeycomb formed body (that is, the cut surface after the cutting step), and only the cells that need to be sealed are filled with the sealing material paste.
Through such steps, a honeycomb formed body filled with the sealing material paste is manufactured.

Next, the honeycomb formed body filled with the sealing material paste is placed on the spacer of the firing jig so that the positional relationship between the honeycomb formed body and the spacer is as described above, and the degreasing temperature is set in a degreasing furnace. A degreasing step of degreasing at 250 to 390 ° C. and an oxygen concentration of 5 to 13% by volume in the atmosphere is performed to remove organic substances in the honeycomb formed body.
Subsequently, with the honeycomb formed body that has undergone the degreasing process placed on the spacer of the firing jig, a firing process is performed in an firing atmosphere in an argon atmosphere, for example, at a firing temperature of 2200 ° C. Make it.

Then, a sealing material paste to be an adhesive layer is applied to the side surface of the obtained honeycomb fired body to form an adhesive paste layer, and other honeycomb fired bodies are sequentially stacked on the adhesive paste layer. A bundling step for producing a honeycomb aggregate in which a predetermined number of honeycomb fired bodies are bundled is performed by repeating the process. In addition, as a sealing material paste, what consists of an inorganic binder, an organic binder, an inorganic fiber, and / or an inorganic particle can be used, for example.

Next, this honeycomb aggregate is heated to dry and solidify the adhesive paste layer to form an adhesive layer. Then, the honeycomb fired body aggregate is cut into a ceramic block using a diamond cutter, and the sealing material paste is applied to the outer peripheral surface of the ceramic block, and the sealing material paste is dried and solidified to form a coating layer. This completes the manufacture of the honeycomb structure.
In addition, as the sealing material paste used for the formation of the adhesive layer and the formation of the coat layer, the same or different ones may be used.

Hereinafter, effects of the manufacturing method of the honeycomb structure of the present embodiment will be listed.
(1) Since the honeycomb formed body is placed on the spacer and the firing process is performed, the formation of coarse silicon carbide particles on the bottom plate of the firing jig is prevented, and a high-strength honeycomb fired body is manufactured. can do.

(2) Since the spacer is not arranged near the center line of the bottom plate of the firing jig, that is, directly below the center of gravity of the honeycomb formed body, the vicinity of the center of the bottom plate of the firing jig is warped in the lifting direction. However, the force applied in the direction of lifting the honeycomb formed body through the spacer is reduced. Therefore, the warp generated in the honeycomb fired body along the direction in which the bottom plate of the firing jig warps can be reduced.
Therefore, even when the firing jig is used repeatedly, a honeycomb fired body with a small warp can be produced.

(3) The spacers are arranged so that the spacer exists on the center of gravity side of the honeycomb molded body with respect to each of two middle points existing between the center of gravity of the honeycomb molded body and the center of gravity of each end face of the honeycomb molded body. Therefore, the force applied to the vicinity of the center of gravity of the honeycomb formed body by its own weight can be reduced.
Therefore, a honeycomb fired body with small warpage can be produced.

(4) With respect to each of two middle points existing between the center of gravity of the honeycomb formed body and the center of gravity of each end face of the honeycomb formed body, spacers are provided so that the spacer exists on the end face side of the honeycomb formed body. Since they are arranged, the force applied to the vicinity of the end face of the honeycomb formed body by its own weight can be reduced. Therefore, a honeycomb fired body with small warpage can be produced.

(5) Since the distance between the two spacers sandwiching the center of gravity of the honeycomb molded body is 25 to 45% of the length in the longitudinal direction of the honeycomb fired body, the force applied in the direction in which the honeycomb molded body sinks is reduced. The effect and the effect of reducing the warp generated in the honeycomb fired body along the direction in which the bottom plate of the firing jig warps can be more effectively exhibited. Therefore, a honeycomb fired body with less warpage can be manufactured.

(6) Since the spacer is arranged at a position overlapping with the midpoint, the spacer includes only one spacer and includes both the area on the center of gravity side and the area on the end face side of the honeycomb fired body with respect to one midpoint. Can be arranged. Therefore, a honeycomb fired body with small warpage can be easily manufactured.

(7) Since the length W of the spacer in the longitudinal direction of the honeycomb formed body is 20 mm or more, the distance between the side closest to the center of gravity of the spacer and the center of gravity of the honeycomb formed body, and the most end face of the spacer The distance between the near side and the end face of the honeycomb formed body is shortened, and the force applied to the vicinity of the center of gravity and the vicinity of the end face of the honeycomb formed body can be reduced. Therefore, a honeycomb fired body with a small warp can be produced.

(8) Since the length W of the spacer in the longitudinal direction of the honeycomb formed body is 50 mm or less, the area of the region where the spacer and the honeycomb formed body are in contact can be reduced. Therefore, the honeycomb fired body having a high strength can be manufactured by sufficiently firing.

(9) Since spacers are arranged at positions that are line symmetric with respect to a straight line that passes through the center of gravity of the honeycomb formed body and is perpendicular to the longitudinal direction of the honeycomb formed body, the vicinity of the center of gravity of the honeycomb formed body and the end faces on both sides The force applied to the vicinity can be dispersed in a balanced manner. Therefore, a honeycomb fired body with less warpage can be manufactured.

(10) Since the force applied to the vicinity of the center of gravity and the vicinity of the end face of the honeycomb formed body can be reduced, the honeycomb fired body with less warpage even though the length in the longitudinal direction of the honeycomb formed body is increased to 305 mm or more. The body can be made.

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.

Example 1
A wet mixing of 52.2 wt% of silicon carbide coarse powder having an average particle size of 22 μm and 22.4 wt% of silicon carbide fine powder having an average particle size of 0.5 μm was carried out. An acrylic resin was added to the resulting mixture. 4.8% by weight, 2.6% by weight of organic binder (methylcellulose), 2.9% by weight of lubricant (Unilube, manufactured by NOF Corporation), 1.3% by weight of glycerol, and 13.8% by weight of water A wet mixture was obtained by kneading.

Next, this wet mixture was charged into an extrusion molding machine, and a molding process was performed in which a columnar honeycomb molded body was continuously extruded. Thereafter, the extruded honeycomb formed body was cut using a cutting member provided in a cutting device, and a honeycomb formed body having the shape shown in FIGS. 2A and 2B was manufactured.
The honeycomb formed body had a size of 33.0 mm × 33.0 mm × 330.2 mm.

Next, after the honeycomb formed body was dried using a drier using both microwave and hot air, a predetermined cell was filled with a sealing material paste having the same composition as the composition used for extrusion molding.

Subsequently, carbon is contained in a box-shaped firing jig (bottom side 350 mm × bottom side 430 mm × height 45 mm) made of porous carbon (G100 manufactured by Tokai Carbon Co., Ltd.) with one main surface opened. Two spacers made of felt (short side 20 mm × long side 410 mm × thickness 5 mm) are arranged, and on each of the two spacers, a constant interval is set so that the longitudinal direction of each honeycomb molded body is orthogonal to the long side of the spacer. Three honeycomb molded bodies were placed.

4A and 4B are plan views schematically showing the positional relationship between the spacer and the honeycomb formed body in each example.
In this embodiment, as shown in FIG. 4A, when the honeycomb molded body placed on the spacer is viewed in plan, the center of gravity LG, RG of the end face in the longitudinal direction of the honeycomb molded body and the honeycomb molded body Two spacers 12 are arranged at positions where each of the two middle points L and R formed by the center of gravity G and each spacer overlap.
Further, in this example, the length W was 20 mm which is the length of the short side of the spacer 12, and the distance E between the spacers was 43.9% with respect to the total length of the honeycomb formed body.

Next, the firing jig in which the honeycomb formed body was placed in the firing jig was carried into a continuous degreasing furnace, and the atmosphere was mixed under a mixed gas atmosphere of air and nitrogen having an oxygen concentration of 9% by volume. A degreasing step for degreasing by heating at ° C. was performed.

Then, the degreased honeycomb molded body is carried on the firing jig while being placed on the firing jig, and subjected to a firing step of firing at 2200 ° C. for about 3 hours in a normal pressure argon atmosphere. A honeycomb fired body was produced.

(Comparative Example 1)
FIGS. 5A to 5D are plan views schematically showing the positional relationship between the spacer and the honeycomb formed body in each comparative example.
In the degreasing step and the firing step, as shown in FIG. 5A, the end surface of the honeycomb formed body and the long side of the spacer overlap with each other so that the spacer is positioned only on the end surface side from the midpoint L or R. A honeycomb fired body was manufactured in the same manner as in Example 1 except for the arrangement.

(Comparative Example 2)
In the degreasing step and the firing step, as shown in FIG. 5B, in addition to the two spacers arranged at the same position as in Comparative Example 1, except that one spacer is arranged so that the center of gravity G and the spacer overlap. Produced the honeycomb fired body in the same manner as in Example 1.

(Comparative Example 3)
In the degreasing step and the firing step, as shown in FIG. 5C, the end face of the honeycomb molded body and the long side of the spacer overlap so that one spacer is located only on the end face side from the midpoint L. A honeycomb fired body was produced in the same manner as in Example 1 except that the other spacer was placed so that the middle point R and the spacer overlapped.

(Comparative Example 4)
In the degreasing step and the firing step, as shown in FIG. 5D, in addition to the two spacers arranged at the same position as in Example 1, one spacer is arranged so that the center of gravity G and the spacer overlap. Produced the honeycomb fired body in the same manner as in Example 1.

(Comparative Example 5)
A honeycomb fired body was manufactured in the same manner as in Example 1 except that in the degreasing process and the firing process, the honeycomb formed body was directly placed on the bottom plate of the firing jig without providing a spacer.

The following evaluation (measurement) was performed on the honeycomb fired bodies obtained in each of the examples and comparative examples described so far.

(1) Measurement of warpage The measurement of the warpage of the honeycomb fired body was performed using a warpage measurement jig.
In this warp amount measuring jig, a straight SUS square member having substantially the same length as the entire length of the molded body is provided with contact members having the same thickness at both ends of the square member. In addition, a scale that can slide perpendicularly to the longitudinal direction of the square bar is attached to the center of the square bar.
At the time of measurement, the contact member is brought into contact with the vicinity of both ends of the molded body, and then the warp amount measuring scale is moved to the molded body side, and the amount of movement of the scale when the molded body and the scale are in contact is read. The amount of warpage was measured. The results are shown in Table 1.
(2) Evaluation of fired state a) Evaluation of bending strength The obtained honeycomb fired body was subjected to a four-point bending strength test with reference to JIS R 1624 to evaluate the bending strength.
Specifically, for the honeycomb fired bodies (5 samples) extracted at random, a bending strength tester (Instron 5582) was used, and the distance between upper spans was 195 mm, the distance between lower spans was 308 mm, and the speed was 51 MPa at 0.35 mm / min. A four-point bending test was performed by applying the above load, and it was determined whether or not each honeycomb fired body was cracked.
The span distance and the load are calculated so that the stress is 30 MPa from the secondary moment of the cross-section considering the length of the compact, the thickness of the cell wall, and the cell density.
The results are shown in Table 1, where no cracks occurred in all 5 samples, .smallcircle. In which cracks occurred in any of the 5 samples, and .DELTA. In which cracks occurred in all 5 samples. .
B) Appearance Evaluation The honeycomb fired body obtained was visually evaluated for the appearance of the area that was in contact with the spacer in the firing step.
The results are shown in Table 1 as ◎ when the surface of the region is not rough, and as ◯, Δ, and X in ascending order of surface roughness.

As is clear from the results shown in Table 1, in Example 1, since the firing process was performed by arranging the spacers so as to overlap each of the two midpoints, the warp of the obtained honeycomb fired body was 0 It was as small as .8mm or less.
Moreover, the honeycomb fired body obtained in Example 1 had sufficient bending strength. From this, it was found that according to the method of Example 1, a honeycomb fired body suitable for manufacturing a honeycomb structure can be produced.

On the other hand, in the honeycomb fired bodies obtained in Comparative Examples 1 to 5, the warpage was larger than 1.0 mm, and the honeycomb fired bodies were unsuitable for manufacturing a honeycomb structure. This warpage is considered to have occurred because the position of the spacer is not appropriate or because the spacer is not used.

(Examples 2 to 4)
In the degreasing step and the firing step, the same procedure as in Example 1 was performed except that a spacer having a short side length of 30 to 50 mm and a length W (30 to 50 mm) shown in Table 2 was disposed. A honeycomb fired body was produced.

(Reference Examples 1-5)
Example 1 except that a spacer having a short side length of 10 mm or 60 to 90 mm and a length W of 10 mm or 60 to 90 mm shown in Table 2 was disposed in the degreasing step and the firing step. A honeycomb fired body was produced in the same manner as described above.

The honeycomb fired bodies obtained in each Example and Reference Example were evaluated for warpage and fired state. The results are shown in Table 2 together with the results of Example 1.

As is clear from the results shown in Table 2, when the spacer length W was 20 mm or more, the warp of the manufactured honeycomb fired body was as small as 0.8 mm or less.
In particular, when the length W was 30 mm or more, the warp of the manufactured honeycomb fired body was as extremely small as 0.5 mm or less.
Moreover, when the length W was 50 mm or less, the bending strength of the obtained honeycomb fired body was good.
This is presumably because the smaller the area where the spacer and the honeycomb formed body are in contact with each other, the more fully the firing is performed.
Moreover, although the distance E changes with the change of the length W, when the distance E is in the range of 25 to 45% as in Examples 1 to 4 and Reference Examples 2 to 4, the warp is 0.8 mm or less. It was low.

(Example 5)
A honeycomb fired body was manufactured in the same manner as in Example 1 except that the cut dimensions when cutting the extruded honeycomb formed body were changed to produce a honeycomb formed body having a length in the longitudinal direction of 355.6 mm. Produced.

(Reference Example 6)
A honeycomb fired body was manufactured in the same manner as in Example 1 except that the cut dimensions when cutting the extruded honeycomb formed body were changed to produce a honeycomb formed body having a length in the longitudinal direction of 304.8 mm. Produced.

(Comparative Example 6)
By changing the cut dimensions when cutting the extruded honeycomb formed body, a honeycomb formed body having a length in the longitudinal direction of 304.8 mm was produced, and in the firing step, as shown in FIG. The honeycomb firing was performed in the same manner as in Example 1 except that the spacer was disposed at a position where the end face of the honeycomb formed body and the long side of the spacer overlapped so that the spacer was located only on the end face side from the midpoint L or R. The body was made.

The honeycomb fired bodies obtained in each of the examples, reference examples and comparative examples were evaluated for warpage and fired state. The results are shown in Table 3 together with the results of Example 1 and Comparative Example 1.
In the measurement of bending strength, the span distance and the load were changed according to the length of the molded body.

As is apparent from the results shown in Table 3, in Examples 1 and 5, the honeycomb fired bodies obtained were obtained even though the length of the honeycomb formed body in the longitudinal direction was as long as 330.2 mm or 355.6 mm. The warpage was as small as 0.8 mm or less.
On the other hand, when the spacer is disposed and fired so that the spacer is located only on the end face side from the midpoint L or R as in Comparative Examples 1 and 6, the length of the molded body is as in Comparative Example 6. Warpage of the obtained honeycomb fired body was not so large as 1.0 mm or less, but when the formed body length was 305 mm or more as in Comparative Example 1, the warp of the obtained honeycomb fired body was It exceeded 1.0 mm.
Further, comparing Reference Example 6 and Comparative Example 6, when the length of the honeycomb formed body in the longitudinal direction is 304.8 mm, the warp of the manufactured honeycomb fired body is not dependent on the position where the spacer is disposed. It was as small as 0.8 mm or less.
Therefore, it has been clarified that by performing the firing step using the method for manufacturing a honeycomb structure of the present invention, warpage can be reduced particularly when the length of the molded body is 305 mm or more.

(Reference Example 7)
In the degreasing step and the firing step, as shown in FIG. 4B, when the honeycomb formed body placed on the spacer is viewed in plan, the length of the short side of the spacer 22 arranged at a position overlapping the midpoint L The length of the short side of the spacer 12 arranged at a position where the middle point R and the spacer overlap each other is 20 mm, two spacers are arranged, and the honeycomb formed body is placed on the two spacers. .
In this reference example, the arranged spacers were not line-symmetric with respect to a straight line that passed through the center of gravity of the honeycomb molded body and was perpendicular to the longitudinal direction of the honeycomb molded body.
Thus, a honeycomb fired body was manufactured in the same manner as in Example 1 except that the length of the short side of the spacer was changed.

The honeycomb fired body obtained in this reference example was evaluated for warpage and fired state. The results are shown in Table 4 together with the results of Example 1.

As is clear from the results shown in Table 4, the warpage was smaller in Example 1 than in Reference Example 7. This is considered to be because in Example 1, the spacers were arranged at positions where the spacers were axisymmetric with respect to a straight line passing through the center of gravity of the honeycomb molded body and perpendicular to the longitudinal direction of the honeycomb molded body. .

(Second embodiment)
Hereinafter, a second embodiment which is an embodiment of the present invention will be described.
In this embodiment, instead of defining the positional relationship between the spacer and the honeycomb formed body so that the spacer overlaps each of the two midpoints in the first embodiment, the midpoint and the spacer overlap. And the positional relationship between the spacer and the honeycomb formed body so that the midpoint is sandwiched between at least two spacers (the center of gravity side spacer and the end surface side spacer) located on the center of gravity side and the end surface side of the honeycomb formed body, respectively. Is stipulated.

FIG. 6 is a plan view schematically showing the positional relationship between the spacer and the honeycomb formed body in the second embodiment.
The spacer used in this embodiment is the same as the spacer used in the first embodiment, but a spacer having a width of 5 to 10 mm can be suitably used.

The honeycomb formed body 120 is placed on the four spacers 32 as shown in FIG.
A center-of-gravity side spacer 32G exists on the center of gravity G side of the left midpoint L, and an end surface side spacer 32E exists on the side of the left end surface center of gravity LG, and the left midpoint L is sandwiched between the two spacers 32.
Similarly, for the right midpoint R, the center of gravity side spacer 32G exists on the center of gravity G side, and the end surface side spacer 32E exists on the right end surface center of gravity RG side. The right midpoint R is sandwiched between the two spacers 32. It is.

In FIG. 6, the position 35L closest to the left end surface center of gravity LG of the end surface side spacer 32E, which is a position on a straight line passing through the left end surface center of gravity LG and the center of gravity G of the honeycomb formed body, and the center of gravity of the center of gravity side spacer 32G Consider the position 34L closest to G. At this time, the distance between the position 35L and the position 34L is a distance indicated by D in FIG.
In the present embodiment, the position of each spacer 32 is determined so that the distance D is 30 to 50 mm.
Similarly, the position 35R, the position 34R, and the distance D can be determined for the right end face side. In the present embodiment, the position of each spacer 32 is set so that the distance D is 30 to 50 mm for the right end face side. It has established.
Further, the positions of the spacers 32 are determined so that the distance D is 9 to 16% of the length in the longitudinal direction of the honeycomb molded body, and the distance D is the length (mm) or the longitudinal direction of the honeycomb molded body. It is expressed as a ratio (%) to the length of.

In the present embodiment, the inter-spacer distance E is determined as a ratio (%) of the distance between the position 34L and the position 34R to the total length of the honeycomb formed body. In the present embodiment, the distance E is 25 to 45%. Thus, the position of each spacer 32 is determined.
In the present embodiment, the length W is 5 to 10 mm which is the length of the short side of the spacer 32.

Also in this embodiment, the effects (1) to (5), (9), and (10) described in the first embodiment can be exhibited.
Moreover, the following effects can be exhibited.
(11) Since the distance D is 30 mm (9%) or more, the distance between the side closest to the center of gravity of the spacer and the center of gravity of the honeycomb formed body, and the side closest to the end face of the spacer and the honeycomb The distance from the end surface of the formed body can be shortened, and the force applied to the vicinity of the center of gravity and the vicinity of the end surface of the honeycomb formed body can be reduced.
Therefore, a honeycomb fired body with small warpage can be produced.

(12) Since the distance D is 50 mm (16%) or less, the distance between the side closest to the midpoint of the spacer and the midpoint can be shortened. Therefore, the force applied in the direction in which the vicinity of the midpoint between the two spacers tends to sink can be reduced.
Therefore, a honeycomb fired body with small warpage can be produced.

(13) Since the length W of the spacer in the longitudinal direction of the honeycomb formed body is 10 mm or less, the area of the region where the spacer and the honeycomb formed body are in contact can be extremely small. Therefore, it is possible to manufacture a honeycomb fired body that is sufficiently fired, has high strength, and has a rough surface in a region where the spacer and the honeycomb formed body are in contact with each other.

(14) If the spacer is too thin, the position of the honeycomb molded body is likely to shift when the honeycomb molded body is placed on the spacer of the firing jig. In this embodiment, the length in the longitudinal direction of the spacer is 5 mm or more. Therefore, the position of the honeycomb formed body can be prevented from shifting.

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

(Example 6)
In the degreasing step and the firing step, as shown in FIG. 6, four spacers made of carbon felt (short side 5 mm × long side 410 mm × thickness 5 mm) were arranged, and the honeycomb formed body was placed on the spacer.
In the present embodiment, the center points L and R are sandwiched between two spacers (center of gravity side spacer and end surface side spacer) located on the center of gravity side and the end surface side, respectively, and the spacers are set so that the distance D is 50 mm. Arranged. A honeycomb fired body was manufactured in the same manner as in Example 1 except that the spacers were arranged in this way.

The honeycomb fired body obtained in this example was evaluated for warpage and fired state. The results are shown in Table 5 together with the results of Example 4.

As is clear from the results shown in Table 5, in Example 6, the spacers were arranged so that each of the two midpoints L and R was sandwiched between the two spacers. The warp of the honeycomb fired body was small.
In particular, since the distance D is set to 50 mm, the warpage is as extremely small as 0.5 mm or less.

Here, the result of Example 6 is compared with the result of Example 4. In the sixth embodiment, the distance D is 50 mm, whereas in the fourth embodiment, the length W is 50 mm.
Then, the warpage was extremely small at 0.5 mm or less in all the examples. This is because both examples have spacers on both sides of the midpoint of the two locations, and the distance between the side closest to the center of gravity of the spacer and the center of gravity of the honeycomb formed body and the end face of the spacer. This is thought to be due to the fact that the distance between the side closer to the end and the end face of the honeycomb formed body is shorter.
However, Example 6 was better in terms of appearance. This is considered to be because firing is more sufficiently performed in Example 6 because the area where the spacer and the honeycomb formed body are in contact with each other is smaller than that in Example 4.

(Examples 7 and 8, Reference Examples 8 and 9)
In the degreasing step and the firing step, the positions where the spacers are arranged are changed so that the distance D is 20 to 60 mm (6 to 18%) and the distance E is 43.9 to 31.8% as shown in Table 6. A honeycomb fired body was produced in the same manner as in Example 6 except that a spacer was disposed on the substrate.

The honeycomb fired bodies obtained in each Example and Reference Example were evaluated for warpage and fired state. The results are shown in Table 6 together with the results of Example 6.

As is apparent from the results shown in Table 6, when the distance D is in the range of 30 to 50 mm (9 to 15%), the warp of the manufactured honeycomb fired body was as extremely small as 0.5 mm or less.

(Example 9, Reference Examples 10 and 11)
In the degreasing step and the firing step, the same procedure as in Example 6 was performed except that a spacer having a short side length of 3 to 12 mm and a length W of 3 to 12 mm shown in Table 7 was disposed. A honeycomb fired body was produced.
At this time, the spacers were arranged so that the distance D was 50 mm (15%) and the distance E was 34.8%.

The honeycomb fired bodies obtained in each Example and Reference Example were evaluated for warpage and fired state. The results are shown in Table 7 together with the results of Example 6.

As is clear from the results shown in Table 7, when the length W is in the range of 5 to 10 mm, the warp of the manufactured honeycomb fired body is as extremely small as 0.5 mm or less, and the bending strength is high. In addition, the appearance was very good.
This is presumably because firing was sufficiently performed because the area of the region where the spacer and the honeycomb formed body were in contact with each other was small. It is also considered that the spacer does not bite into the honeycomb formed body.

(Third embodiment)
Hereinafter, a third embodiment which is an embodiment of the present invention will be described.
In this embodiment, in addition to the spacers arranged in the second embodiment, the spacers are also arranged at positions where the spacers overlap each of the two midpoints.

FIG. 7 is a plan view schematically showing the positional relationship between the spacer and the honeycomb formed body in the third embodiment.
The honeycomb formed body 120 is placed on the six spacers 32 as shown in FIG.
Since the center-of-gravity side spacer 32G exists on the center of gravity G side with respect to the left center point L, and the end surface side spacer 32E exists on the left end surface center of gravity LG side, the left center point L is sandwiched between the two spacers 32. Yes.
Furthermore, the spacer 32 exists also in the position which overlaps with the left midpoint L.
Similarly, for the right midpoint R, the center of gravity side spacer 32G is present on the center of gravity G side, the end surface side spacer 32E is present on the right end surface center of gravity RG side, and further, at the position overlapping the right midpoint R. Spacers 32 are present.

Also in this embodiment, the effects (1) to (5) and (9) described in the first embodiment and the effects (11) to (14) described in the second embodiment can be exhibited.

Hereinafter, examples that more specifically disclose the third embodiment of the present invention will be described. In addition, this invention is not limited only to these Examples.

(Example 10)
In the degreasing step and the firing step, as shown in FIG. 7, six spacers made of carbon felt (short side 5 mm × long side 410 mm × thickness 5 mm) were arranged, and the honeycomb formed body was placed on the spacer.
In this embodiment, the midpoints L and R are sandwiched between two spacers 32 (center of gravity side spacer and end surface side spacer) located on the center of gravity side and the end surface side, respectively, and the midpoints L and R are respectively The spacer was arranged so as to overlap with the spacer 32.
At this time, the spacers were arranged so that the distance D was 50 mm (15%) and the distance E was 34.8%. A honeycomb fired body was manufactured in the same manner as in Example 1 except that the spacers were arranged in this way.

The honeycomb fired body obtained in this example was evaluated for warpage and fired state. The results are shown in Table 8 together with the results of Examples 4 and 6.

As is apparent from the results shown in Table 8, in Example 10, each of the two midpoints is sandwiched between the two spacers, and each of the two midpoints overlaps with the spacers. Since the firing process was performed with the spacers arranged, warpage of the obtained honeycomb fired body was small.
In particular, since the distance D was set to 50 mm (15%), the warpage was extremely small at 0.5 mm or less.
The result of Example 10 was almost the same as the result of Example 6, and the appearance was better than that of Example 4. Also in Example 10, the area of the region where the spacer and the honeycomb formed body are in contact with each other is small as compared with Example 4, and thus it is considered that the firing was sufficiently performed.

(Other embodiments)
The spacer that can be used in each embodiment will be described in detail below.
The material of the spacer is not particularly limited as long as it can withstand the high temperature during the firing process, and a ceramic member having heat resistance can be suitably used.
Further, when a space is formed between the firing jig and the honeycomb formed body using the spacer, heat transfer to the honeycomb formed body is mainly performed through the spacer existing under the honeycomb formed body. Therefore, in order to advance the sintering of the honeycomb formed body quickly, it is desirable that the spacer has a high thermal conductivity.
For this reason, carbon, silicon carbide, aluminum nitride, silicon nitride, or the like can be used as the ceramic member.
In addition, the said ceramic member used as a spacer can be variously changed according to the material which comprises the honeycomb molded object to be fired.

Among these, a carbon felt made by combining carbon fibers into a cloth-like shape or a fiber-like carbon fiber assembled is preferable. This is because they are not too hard and are difficult to damage the honeycomb formed body.

The bulk density of the carbon felt is desirably 0.3 g / cm ³ or less, and more desirably 0.1 g / cm ³ or less. When the bulk density is within this range, the honeycomb molded body is not damaged, the contact area between the honeycomb molded body and the carbon felt is small, and the SiO gas generated from the honeycomb molded body passes through the carbon felt. Therefore, it is difficult for coarse particles made of silicon carbide to be formed by the reaction between the honeycomb formed body and the carbon felt.

The thickness of the spacer is preferably 1.0 mm or more in consideration of providing a space between the firing jig and the honeycomb formed body, and 10.0 mm in consideration of heat conduction to the honeycomb formed body. The following is desirable.
Further, the specific shape of the spacer is not particularly limited, but a quadrangular prism shape is desirable from the viewpoint of stability when the honeycomb formed body is placed.

The honeycomb structure manufactured in the present embodiment is not limited to the honeycomb structure in which the cells are sealed. A honeycomb structure in which cells are sealed can be suitably used as a honeycomb filter, and a honeycomb structure in which cells are not sealed can be suitably used as a catalyst carrier.
Therefore, in the method for manufacturing a honeycomb structure of the present embodiment, it is not always necessary to fill the plug material paste, and filling may be performed as necessary.

The main component of the constituent material of the honeycomb structure is not limited to silicon carbide. Other ceramic raw materials include, for example, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, zirconium carbide, and carbonized Examples thereof include inorganic powders such as carbide ceramics such as titanium, 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 addition, the particle size of the silicon carbide powder is not particularly limited, but those having less shrinkage in the subsequent firing step are preferable. For example, 100 parts by weight of powder having an average particle size of 1.0 to 50 μm and 0.1 to 1. A combination of 5 to 65 parts by weight of a powder having an average particle size of 0 μm is preferred.
In order to adjust the pore diameter and the like of the honeycomb fired body, it is necessary to adjust the firing temperature, but the pore diameter can be adjusted by adjusting the particle size of the inorganic powder.

The organic binder in the wet mixture is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and polyethylene glycol. Of these, methylcellulose is desirable. Usually, the blending amount of the organic binder is desirably 1 to 10 parts by weight with respect to 100 parts by weight of the inorganic powder.
The plasticizer in the wet mixture is not particularly limited, and examples thereof include glycerin. The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
Specific examples of the lubricant include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the mixed raw material powder.

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 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.

Moreover, it is desirable that the temperature of the wet mixture using the silicon carbide powder prepared here is 28 ° C. or less. It is because an organic binder may gelatinize when temperature is too high.
Further, the organic content in the wet mixture is desirably 10% by weight or less, and the water content is desirably 8 to 20% by weight.

Although it does not specifically limit as a sealing material paste which seals a cell, The thing from which the porosity of the sealing material manufactured through a post process becomes 30 to 75% is desirable, For example, the thing similar to a wet mixture is used. be able to.

Further, when an aggregate of honeycomb fired bodies is manufactured, the honeycomb fired bodies are assembled in advance through spacers, and then a sealing material paste is injected into the gaps between the honeycomb fired bodies. You may produce the aggregate | assembly of.

Examples of the inorganic binder in the sealing material 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 organic binder in the sealing material paste include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Among organic binders, carboxymethylcellulose is desirable.

Examples of inorganic fibers in the sealing material paste include ceramic fibers such as silica-alumina, mullite, alumina, and silica. These may be used alone or in combination of two or more. Among inorganic fibers, alumina fibers are desirable.

Examples of the inorganic particles in the sealing material paste include carbides and nitrides. Specific examples include inorganic powders made of silicon carbide, silicon nitride, and boron nitride. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide having excellent thermal conductivity is desirable.

Furthermore, a pore-forming agent such as a balloon, which is a fine hollow sphere containing an oxide ceramic as a component, spherical acrylic particles, or graphite may be added to the sealing material paste 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.

A desirable form of each step in each embodiment will be described in detail below.
After the honeycomb formed body is manufactured by extrusion, it is not always necessary to perform a drying process, and it may be performed as necessary. Further, after the end of the cell is filled with the sealing material paste, the drying treatment may be performed.
In addition, when performing the drying treatment of the honeycomb formed body, in addition to a dryer combining microwave and hot air, for example, a microwave dryer, a hot air dryer, a vacuum dryer, a dielectric dryer, a freeze dryer, etc. May be used.

Further, the step of filling the end portions of the cells of the honeycomb formed body with the sealing material paste is not necessarily performed and may be omitted. When the step of filling the plug material paste is omitted, the completed honeycomb structure can be suitably used as a catalyst carrier for supporting the catalyst.

The degreasing step and the firing step are not necessarily performed using the same firing jig, and a degreasing jig different from the firing jig may be used in the degreasing step. In this case, the degreased honeycomb formed body can be taken out from the degreasing jig and placed on a spacer disposed on the firing jig to perform the firing step.

A catalyst may be supported on the honeycomb structure manufactured in the present invention as necessary. The catalyst may be supported on the honeycomb fired body before the honeycomb aggregate is produced.
When the catalyst is supported, it is desirable to form an alumina film having a high specific surface area on the surface of the honeycomb structure, and to apply a promoter such as platinum and a catalyst such as platinum to the surface of the alumina film.

As a method for forming an alumina film on the surface of the honeycomb structure, for example, a method in which the honeycomb structure is impregnated with a solution of a metal compound containing aluminum such as Al (NO ₃ ) ₃ and heated, and alumina powder is contained. Examples include a method of impregnating the honeycomb structure with a solution and heating.
Examples of the method for applying the promoter include a method in which a honeycomb structure is impregnated with a solution of a metal compound containing a rare earth element such as Ce (NO ₃ ) ₃ and heated.
As a method for applying the catalyst, for example, a honeycomb structure is impregnated with a dinitrodiammine platinum nitric acid solution ([Pt (NH ₃ ) ₂ (NO ₂ ) ₂ ] HNO ₃ , platinum concentration of about 4.53% by weight). The method of heating etc. can be mentioned.
Alternatively, the catalyst may be applied by a method in which a catalyst is applied to the alumina particles in advance, and the honeycomb structure is impregnated with a solution containing the alumina powder to which the catalyst is applied and heated.

It is a perspective view which shows typically an example of a honeycomb structure. (A) is a perspective view schematically showing a honeycomb fired body constituting the honeycomb structure shown in FIG. 1, and (b) is a cross-sectional view taken along the line AA. (A) is a partially cutaway perspective view schematically showing a method of placing a honeycomb formed body in a firing jig in the first embodiment of the present invention, and (b) is a perspective view of FIG. ) Is a plan view of a portion indicated by B in FIG. It is a top view which shows typically the positional relationship of the spacer and honeycomb molded object in each Example. It is a top view which shows typically the positional relationship of the honeycomb molded object and spacer in each comparative example. It is a top view which shows typically the positional relationship of the spacer and honeycomb molded object in 2nd embodiment. It is a top view which shows typically the positional relationship of the spacer and honeycomb molded object in 3rd embodiment. It is sectional drawing which shows typically the method which arrange | positions a spacer on the surface of the jig | tool for baking, and mounts a honeycomb molded object on a spacer and performs a baking process. It is sectional drawing which shows typically a mode that the gravity center vicinity of the honeycomb molded object mounted on the spacer sinks and warps. FIG. 5 is a partially cutaway perspective view schematically showing an example of a method of placing a spacer in a firing jig by placing a spacer immediately below the center of gravity of a honeycomb formed body in a firing step. It is sectional drawing which shows typically a mode that the gravity center vicinity of the honeycomb molded object mounted on the spacer lifts and warps.

Explanation of symbols

10 Firing jig 11 Bottom plates 12, 22, 32 Spacers 14L, 34L The closest position to the center of gravity (left)
14R, 34R Position closest to the center of gravity (right)
15L, 35L End face closest to the center of gravity (left)
15R, 35R Position closest to the center of gravity of the end face (right)
32E End face side spacer 32G Center of gravity side spacer 100 Honeycomb structure 101 Adhesive layer 110 Honeycomb fired body 111 Cell 113 Cell wall 120 Honeycomb molded body 125 Left end face (end face)
126 Right end face (end face)
G Center of gravity L of honeycomb molded body Left midpoint (midpoint between the center of gravity and the center of gravity of the end face)
R Right midpoint (midpoint between the center of gravity and the center of gravity of the end face)
LG Left side center of gravity (end center of gravity)
RG Right side edge center of gravity (end surface center of gravity)

Claims (11)

A forming step for producing a columnar honeycomb formed body in which a large number of cells are arranged in parallel in the longitudinal direction across a cell wall;
A firing step of producing a honeycomb fired body by placing the honeycomb formed body on a spacer disposed on a bottom plate of a firing jig and performing a firing treatment;
A honeycomb structure manufacturing method including a binding step of manufacturing a honeycomb aggregate by binding a plurality of the honeycomb fired bodies through an adhesive layer,
In the firing step, the spacers are disposed in at least two places so as to sandwich the center of gravity of the honeycomb molded body in the longitudinal direction when the honeycomb molded body placed on the spacer is viewed in plan view, And,
The spacer is a region on the center of gravity side of each center point existing between the center of gravity when the honeycomb formed body is viewed in plan and the center of gravity of both end faces in the longitudinal direction of the honeycomb formed body and the end surface side. A method for manufacturing a honeycomb structure, wherein the honeycomb structure is disposed so as to include both of the regions. The method for manufacturing a honeycomb structured body according to claim 1, wherein a distance between the two spacers sandwiching the center of gravity is 25 to 45% of a length in a longitudinal direction of the honeycomb fired body. In the firing step, the spacer is disposed at a position overlapping each of the two midpoints when the honeycomb formed body placed on the spacer is viewed in plan view. 3. A method for manufacturing a honeycomb structure according to 2. The method for manufacturing a honeycomb structured body according to claim 3, wherein a length of the spacer overlapping the midpoint in the longitudinal direction is 20 to 50 mm. In the firing step, when the honeycomb formed body placed on the spacer is viewed in plan, the spacers are arranged so that each middle point is sandwiched between at least two spacers. The honeycomb according to claim 1 or 2, wherein a center-of-gravity side spacer is disposed in a region on the center of gravity side of the honeycomb formed body, and an end surface side spacer is disposed in a region on the end surface side of the honeycomb formed body from each midpoint. Manufacturing method of structure. The method for manufacturing a honeycomb structure according to claim 5, wherein a distance between a position closest to the center of gravity of the end surface of the end surface side spacer and a position closest to the center of gravity of the center of gravity side spacer is 30 to 50 mm. The distance between the position closest to the center of gravity of the end surface of the end surface side spacer and the position closest to the center of gravity of the center of gravity side spacer is 9 to 16% of the length in the longitudinal direction of the honeycomb fired body. 6. A method for manufacturing a honeycomb structured body according to 5. The method for manufacturing a honeycomb structured body according to any one of claims 5 to 7, wherein lengths of the end face side spacer and the gravity center side spacer in the longitudinal direction are 5 to 10 mm. In the firing step, when the honeycomb formed body placed on the spacer is viewed in plan, the spacer is line symmetric with respect to a straight line that passes through the center of gravity of the honeycomb formed body and is perpendicular to the longitudinal direction. The method for manufacturing a honeycomb structured body according to any one of claims 1 to 8, wherein the honeycomb structured body is disposed at a position where The method for manufacturing a honeycomb structured body according to any one of claims 1 to 9, wherein a length of the honeycomb formed body in a longitudinal direction is 305 mm or more. The method for manufacturing a honeycomb structured body according to any one of claims 1 to 10, wherein the honeycomb formed body is manufactured by forming a raw material composition containing at least silicon carbide powder and a binder.

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