JP2000280222A - Method for sealing ceramic molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply appropriately sealing to an end face of a ceramic molded product by a method wherein after penetrating a sealing paste into a through- hole of the ceramic molded product from a gap of a mask, the ceramic molded product is separated from the mask. SOLUTION: At first a state wherein a ceramic molded product 21 is disposed above a mask 11 is provided. That is, while the mask 11 is stuck close to an end face 21a of the ceramic molded product 21 as it is, a sealing paste discharge tank and the ceramic molded product are rotated so that the ceramic molded product 21 is disposed above the mask 11, and a main face of the mask 11 becomes almost horizontal. Thereafter, the ceramic molded product 21 is separated from the mask 11 (b). In this case, an upper part of a webbing part of a sealing paste 13 becomes thin and therefore, the sealing paste 13 is broken in the upper part. Consequently the sealing paste 13 after end of a separating process is not overly protruded from an end face of the ceramic molded product 21 (c). After end of a drying process, almost the same shape is also maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a columnar ceramic molded body in which a large number of through holes are arranged in the longitudinal direction.

[0002]

2. Description of the Related Art Recently, it has become a problem that particulates contained in exhaust gas discharged from internal combustion engines such as vehicles such as passenger cars, buses and trucks and construction machines cause harm to the environment and human bodies. Various ceramic filters have been proposed which purify the exhaust gas by collecting particulates in the exhaust gas by passing the exhaust gas through a porous ceramic.

[0003] The ceramic filter usually comprises a plurality of porous ceramic members 30 as shown in FIG. As shown in FIG. 4, the porous ceramic member 30 has a large number of through holes 31 arranged in the longitudinal direction, and a porous partition wall 33 separating the through holes 31 functions as a filter. ing.

[0004] That is, as shown in FIG. 4 (b), the through hole 31 formed in the porous ceramic member 30 is formed such that either the end of the exhaust gas on the inlet side or the outlet side is filled with the filler 3.
The exhaust gas which is sealed by the second and flows into one through-hole 31 always passes through a partition 33 separating the through-hole 31 and then flows out from the other through-hole 31. When passing through, the particulates are captured at the partition wall 33 and the exhaust gas is purified.

Conventionally, such a porous ceramic member 3
In the production of No. 0, first, a ceramic powder, a binder, and a dispersion medium are mixed to prepare a mixed composition for producing a molded article, and then a large number of the mixed compositions are extruded. Is formed into a columnar ceramic molded body in which the through holes are juxtaposed in the longitudinal direction across the partition wall, and cut into predetermined lengths.

Next, the obtained ceramic molded body is dried and the dispersion medium liquid is scattered to obtain a dried ceramic molded body having a certain strength and easy to handle.
Subsequently, the end of the through-hole of the ceramic molded body is sealed with a sealing paste mainly composed of ceramic powder constituting the ceramic molded body. Thereafter, the ceramic molded body is fired to form the porous ceramic member 30.
Had been manufactured.

FIG. 5A is a cross-sectional view schematically showing this sealing device, and FIG. 5B is a partially enlarged cross-sectional view showing a part thereof. Conventionally, in the sealing step, as shown in FIG. 5, a mask 11 having openings 11a formed in a sealing pattern is installed on a side surface, and a stirring piece 12 is provided therein.
And the following sealing process is performed using the sealing paste discharge tank 10 in which the inside is filled with the sealing paste 13.

[0008] When the ceramic molded body 21 moves to a portion where the sealing paste discharge tank 10 is installed through a predetermined transportation path or the like, first, the sealing paste discharge tank 1 is moved.
By moving 0, the mask 11 is brought into contact with the end face 21a of the ceramic molded body 21. At this time, opening 1
1a and the through-hole 22 portion of the ceramic molded body 21 have a positional relationship that directly opposes each other. Subsequently, the stirring paste 12 is moved up and down while a little pressure is applied to the sealing paste 13 to stir the sealing paste 13, and the sealing paste 13 flows, and the sealing paste 13 opens the mask 11. 5A, the sealing paste 13 enters the end of the through hole 22 of the ceramic molded body 21 as shown in FIG. 5B. When the filling of the sealing paste 13 is completed by the above process, the main surface of the mask 11 and the end surface 21a of the ceramic molded body 21 are kept vertical,
The plugging paste discharge tank 10 is moved, and the mask 11 is separated from the end face 21 a of the ceramic molded body 21, thereby separating the plugging paste 13 in the tank and the plugging paste 13 inside the through-hole 22, thereby completing the plugging step. Was.

However, as shown in FIG. 6, since the sealing paste 13 has a high viscosity, when the mask 11 is separated from the end face of the ceramic molded body 21, the sealing paste 13 is in a so-called stringing state. After the center of the drawn portion is thinned, the sealing paste 13 is cut off at the center portion, so that the ceramic molded body 21 shown in FIG.
A projection was formed on the end face of the sample, or a downward drooping occurred as shown by B.

[0010] If a projection or the like is formed on the end face of the ceramic molded body 21, the projection is also formed on the end face of the porous ceramic member after firing, so that the following problem arises. That is, a plurality of the porous ceramic members are thereafter bundled and bonded, processed into the shape of the filter 40 shown in FIG. 3, and then a sealing material 42 is applied to the periphery thereof.

When the sealing material 42 is applied, a film is stuck on the end face portion so that the sealing material 42 does not adhere to the end face of the filter 40. If the projection is formed on the end face, the film is completely There is a problem that the sealing material 42 flows into the end face portion without adhering to the end face.

Further, as shown by C in FIG. 7, when dripping of the plugging paste 13 is large, the plugging paste 13 flows into the other through-holes 22 of the ceramic molded body 21 which should not be plugged and the plugging paste 13 flows. There was also a problem of doing it.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in order to solve these problems, and it is intended to seal without forming protrusions or dripping made of a sealing paste on an end face of a ceramic molded body. An object of the present invention is to provide a method for sealing a ceramic molded body, which can appropriately perform a sealing process without causing a problem such as sealing a through hole that should not be formed.

[0014]

According to a first aspect of the present invention, an end portion of the through-hole of a columnar ceramic molded body in which a large number of through-holes are juxtaposed in a longitudinal direction with a partition wall therebetween is mainly made of ceramic powder. A method for sealing a ceramic molded body that is sealed with a sealing paste as a component, wherein a mask having an opening formed in a sealing pattern is brought into contact with an end surface of the ceramic molded body,
After injecting the sealing paste into the through-hole of the ceramic molded body from the opening of the mask, the ceramic molded body and the mask are separated from each other while the ceramic molded body is located above the mask. This is a method for sealing a ceramic molded body.

In a second aspect of the present invention, an end of the through hole of a columnar ceramic molded body in which a large number of through holes are arranged in a longitudinal direction with a partition wall therebetween is sealed with a ceramic powder as a main component. A method for sealing a ceramic molded body that is sealed with a paste for use, wherein a mask having an opening formed in a sealing pattern is brought into contact with an end surface of the ceramic molded body, and the paste for sealing is removed from the opening of the mask through the opening. A method for sealing a ceramic molded body, characterized in that the ceramic molded body is separated from the mask while the mask is positioned above the ceramic molded body after the ceramic molded body is penetrated into a through hole of the ceramic molded body.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the method for sealing a ceramic molded body according to the present invention will be described with reference to the drawings.

According to a first aspect of the present invention, there is provided a sealing paste comprising a ceramic powder as a main component, wherein the end of the through-hole of a columnar ceramic molded body having a large number of through-holes arranged in a longitudinal direction across a partition wall. A method of sealing a ceramic molded body, wherein a mask having an opening formed in a sealing pattern is brought into contact with an end face of the ceramic molded body, and the paste for sealing is molded from the opening of the mask through the ceramic molding. A method for sealing a ceramic molded body, characterized in that the ceramic molded body is separated from the mask while the ceramic molded body is located above the mask after the ceramic molded body is penetrated into a through hole of the body.

The ceramic molded body to be subjected to the sealing treatment in the first invention is formed mainly of ceramic powder, a binder and the like, and these are mixed to form a mixed composition for producing a molded body. After the preparation, the mixed composition is subjected to extrusion molding and the like, and then dried to produce a columnar ceramic molded body in which a large number of through-holes are juxtaposed in the longitudinal direction across the partition walls.

The ceramic powder is not particularly restricted but includes, for example, silicon carbide, silicon nitride, aluminum nitride,
Non-oxide ceramic powders such as boron nitride, titanium nitride, titanium carbide; alumina, cordierite, mullite,
Examples include powders of oxide ceramics such as silica, zirconia, and titania. Among these, silicon carbide, silicon nitride, aluminum nitride, and the like having excellent heat resistance are preferable.

The particle size of these ceramic powders is not particularly limited either, but preferably has a small shrinkage in the subsequent firing step, for example, 100 parts by weight of a powder having an average particle size of about 0.3 to 50 μm. What combined with 5 to 65 weight part of powder which has an average particle diameter of about 0.1-1.0 micrometer is preferable.

The binder is not particularly limited.
For example, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethylene glycol, phenol resin, epoxy resin and the like can be mentioned. Usually, the amount of the binder is preferably about 1 to 10 parts by weight based on 100 parts by weight of the ceramic powder. Examples of the dispersion medium liquid that imparts fluidity to the mixed composition include an organic solvent such as benzene; an alcohol such as methanol; and water.

In the first aspect of the present invention, first, a mask having openings formed in a sealing pattern is brought into contact with an end face of the ceramic molded body, and the sealing paste is passed through the openings of the mask to form the ceramic molded body. Into the through hole.

The opening formed in the mask may have the same shape as the cross section of the through hole of the ceramic molded body to be sealed, or may have a smaller shape. By making the shape smaller than the cross section of the through-hole, projections and sagging are less likely to be formed. However, if the opening is too small, the discharge amount of the sealing paste is reduced, and the sealing may not be completed completely. Therefore, the shape of the opening is appropriately determined depending on the size of the through hole of the ceramic molded body, the viscosity of the sealing paste, and the like.

The above-mentioned plugging paste is not particularly limited either, but it is preferable that the paste is easily integrated with the ceramic molded body when fired, and that the paste has substantially the same components as the slurry used for producing the ceramic molded body. Or those to which a dispersion medium is further added. In the first aspect of the present invention, the viscosity of the sealing paste is within a certain range described below. Therefore, by using the sealing method of the first aspect of the present invention, the sealing paste 13 is formed into the ceramic molded body 2.
This has the effect of not protruding too much from the end surface 21a of the first.

The method for injecting the sealing paste from the opening of the mask into the through-hole of the ceramic molded body is not particularly limited. For example, a method of injecting the sealing paste by applying a predetermined amount of the sealing paste to the mask. As shown in FIG. 5A, a mask 11 is installed on a side surface, a stirring piece 12 is provided therein, and
A method using the sealing paste discharge tank 10 whose inside is filled with the sealing paste 13 is preferable because the sealing efficiency is high.

The method for injecting the sealing paste 13 from the opening 11a into the end of the through hole 22 may be the same as in the conventional case. That is, while applying a slight pressure to the sealing paste 13, the stirring piece 12 is moved up and down to flow the sealing paste 13, thereby discharging the sealing paste 13 from the opening of the mask 11, and forming the ceramic molded body. 21 into the end of the through hole 22.

In the first aspect of the present invention, thereafter, the operation of separating the ceramic molded body and the mask is performed with the ceramic molded body being placed above the mask. FIG. 1 (a)-
(C) is a cross-sectional view schematically showing this step. As shown in FIG. 1A, first, the ceramic molded body 21 is placed above the mask 11. That is, while the mask 11 is kept in close contact with the end face 21a of the ceramic molded body 21, the sealing paste is discharged so that the ceramic molded body 21 is above the mask 11 and the main surface of the mask 11 is substantially horizontal. Vessel 10 and ceramic molded body 21
And rotate.

In order to rotate the sealing paste discharge tank 10 in this manner, the sealing apparatus including the sealing paste discharge tank 10 is, of course, provided with a rotation mechanism using a motor or the like. The tank itself is completely sealed so that the sealing paste 13 does not spill or the sealing paste 13 once entering the end of the ceramic molded body 21 does not return to the tank side. In addition, the ceramic molded body 21 and the paste discharging tank 10 for sealing are configured to rotate in an integrated state.

After the above steps, as shown in FIG.
The ceramic molded body 21 and the mask 11 are separated by moving only the ceramic molded body 21 upward, moving only the sealing paste discharge tank 10 downward, or simultaneously moving both in the opposite direction. In the sealing device shown in FIG. 5, since the mask 11 is in contact with both end surfaces of the ceramic molded body 21, the separating operation is sequentially performed. For example, after the sealing paste discharge tank 10 on the right side is separated in the above state, Then, the sealing paste discharge tank 10 on the left side is separated in the above state.

In the above separating operation, the sealing paste 1
When the viscosity of No. 4 is about 5,000 to 8000 cP at room temperature, when the ceramic molded body 21 and the mask 11 are separated from each other, as shown in FIG. The sealing paste 13 is cut off at the upper portion. As a result, as shown in FIG. 1C, the sealing paste 13 after the separation step does not protrude much from the end face of the ceramic molded body 21 and substantially the same after the drying step. Keep shape.

As described above, by using the sealing method of the first aspect of the present invention, it is possible to prevent a projection made of the sealing paste from being formed on the end face portion of the ceramic molded body or to prevent dripping. The ceramic molded body 21
When separating the mask 11 from the mask 11, the main surface of the mask 11 and the end surface 21a of the ceramic molded body 21 do not need to be completely horizontal, and may be inclined to about ± 45 °.

Next, the second invention will be described. According to a second aspect of the present invention, an end of the through-hole of a columnar ceramic molded body in which a large number of through-holes are juxtaposed in the longitudinal direction with a partition wall therebetween is sealed with a sealing paste containing a ceramic powder as a main component. In a method for sealing a ceramic molded body, a mask having an opening formed in a sealing pattern is brought into contact with an end face of the ceramic molded body, and the sealing paste is passed through the ceramic molded body from the opening of the mask. A method for sealing a ceramic molded body, comprising separating the ceramic molded body from the mask while the mask is positioned above the ceramic molded body after the hole has penetrated the hole.

The ceramic molded body to be subjected to the sealing treatment in the second present invention is exactly the same as that in the first present invention. Also in the second invention, first, a mask having an opening formed in a sealing pattern is brought into contact with the end face of the ceramic molded body, and the sealing paste is passed through the ceramic molded body from the opening of the mask. Allow to penetrate holes.

The opening formed in the mask may have the same shape as the cross section of the through hole of the ceramic molded body to be sealed, as in the first invention, or may have a smaller shape. The shape of the opening is appropriately determined depending on the size of the through hole of the ceramic molded body, the viscosity of the sealing paste, and the like.

The composition of the sealing paste is not particularly limited as in the first invention, but its viscosity must be 5,000 to 8,000 cP at room temperature.

The method for injecting the sealing paste from the opening of the mask into the through-hole of the ceramic molded body is not particularly limited. For example, a method using the sealing paste discharge tank 10 shown in FIG. This is preferable because the sealing efficiency is high. In addition, the sealing paste 13 is opened with the opening 11a.
The method for invading the end of the through-hole 22 from the same may be the same as that of the first invention.

In the second aspect of the present invention, thereafter, the operation of separating the ceramic molded body and the mask is performed with the mask placed above the ceramic molded body. FIG.
(C) is a cross-sectional view schematically showing this step. As shown in FIG. 2A, first, the mask 11 is placed above the ceramic molded body 21. That is, while the mask 11 is kept in close contact with the end surface 21a of the ceramic molded body 21, the sealing paste is discharged so that the mask 11 is above the ceramic molded body 21 and the main surface of the mask 11 is substantially horizontal. Vessel 10 and ceramic molded body 21
And rotate. In order to rotate the plugging paste discharge tank 10 in this manner, the plugging device needs to be configured similarly to the device described in the first present invention.

Thereafter, as shown in FIG. 2B, only the ceramic molded body 21 is moved downward, only the sealing paste discharge tank 10 is moved upward, or both are simultaneously moved in the opposite direction. By moving, the ceramic molded body 21 and the mask 11 are separated.

When the viscosity of the sealing paste 14 is about 5,000 to 8,000 cP at room temperature, when the ceramic molded body 21 and the mask 11 are separated from each other, as shown in FIG.
As shown in (2), the lower part of the threading portion of the sealing paste 13 is thinned, and therefore, the sealing paste 13 is cut off at the lower part. Therefore, as shown in FIG. 2C, the sealing paste 13 after the separation step does not protrude much from the end surface of the ceramic molded body 21 and has substantially the same shape even after the drying step. Hold.

As described above, by using the method of the second aspect of the present invention, it is possible to prevent a projection made of the sealing paste from being formed on the end face portion of the ceramic molded body or to prevent dripping. When the ceramic molded body 21 and the mask 11 are separated from each other, the main surface of the mask 11 and the end surface 21a of the ceramic molded body 21 do not need to be completely horizontal, as in the case of the first present invention. It may be tilted to the left or right to the extent.

As described above, when the ceramic molded body is subjected to the sealing treatment, the viscosity of the sealing paste is measured by measuring the viscosity of the sealing paste, and the sealing value of the first present invention is determined based on the viscosity value. By using the method, or by using the above-described sealing method of the second present invention, it is possible to prevent a projection made of a sealing paste from being formed on the end face portion of the ceramic molded body, or to prevent dripping. it can.

[0042]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 70 parts by weight of α-type silicon carbide powder having an average particle diameter of 30 μm, 30 parts by weight of β-type silicon carbide powder having an average particle diameter of 0.28 μm,
5 parts by weight of methylcellulose, 4 parts by weight of a dispersant, and 20 parts by weight of water were blended and uniformly mixed to prepare a mixed composition of raw materials. This mixed composition was filled in an extruder, and a ceramic molded body was produced at an extrusion speed of 2 cm / min. This ceramic molded body has a size of 50 mm ×
It was 50 mm × 300 mm, the number of the through holes was 324, and the length of one side of the through holes was 1.5 mm.

Next, the plugging treatment was performed by the method described in the first invention (the method shown in FIG. 1) using the plugging paste discharge tank 10 shown in FIG. At this time, the viscosity of the sealing paste containing α-type silicon carbide powder and using a glycol ether-based solvent as a dispersion solvent was 6000 cP at room temperature and 4000 cP at 40 ° C.

Thereafter, the ceramic molded body after the sealing treatment was dried, and the dried paste for sealing was 0.5 m from the end face of the ceramic molded body with respect to the number of the through holes subjected to the sealing treatment.
The percentage of the protrusions of m or more (hereinafter, referred to as protrusion ratio) was measured. As a result, the protrusion ratio was 15%.

Comparative Example 1 The same ceramic molded body as in Example 1 was used as a ceramic molded body to be sealed. Further, as the sealing device, the sealing paste discharging tank 10 shown in FIG.
Then, as shown in FIG. 6, the mask 1
The ceramic molded body 21 and the sealing paste discharge tank 10 were separated from each other with the main surface 1 and the end surface 21a of the ceramic molded body 21 kept vertical. Thereafter, the protrusion ratio was measured in the same manner as in Example 1, and as a result, the protrusion ratio was as large as 50%.

[0047]

Since the first and second methods for sealing a ceramic molded body of the present invention are as described above, projections and dripping of sealing paste are not formed on the end face of the ceramic molded body. In addition, the sealing process can be appropriately performed without causing a problem such as sealing a through hole that should not be sealed.

[Brief description of the drawings]

1 (a) to 1 (c) are cross-sectional views schematically showing some steps in a method for sealing a ceramic molded body of the first invention.

FIGS. 2A to 2C are cross-sectional views schematically showing some steps in a second method for sealing a ceramic molded body of the present invention.

FIG. 3 is a perspective view schematically showing a ceramic filter.

FIG. 4A is a perspective view schematically showing a porous ceramic member, and FIG. 4B is a cross-sectional view taken along line AA in FIG.

5A is a cross-sectional view schematically showing a sealing device for a ceramic molded body, and FIG. 5B is a partially enlarged cross-sectional view showing a part of the sealing device.

FIG. 6 is a cross-sectional view schematically showing a state of a sealing paste when a sealing paste discharge tank is separated from a ceramic molded body in a conventional sealing method.

FIG. 7 is a cross-sectional view schematically showing a problematic state when a conventional method for sealing a ceramic molded body is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Paste discharge tank for sealing 11 Mask 11a Opening hole 12 Stirring piece 13 Paste for sealing 21 Ceramic molded body 21a End face 22 Through hole 23 Partition wall 30 Porous ceramic member 31 Through hole 32 Filler 33 Partition wall 40 Ceramic filter

Claims (2)

[Claims] 1. A ceramic molding method for sealing an end of a through-hole of a columnar ceramic molded body in which a large number of through-holes are juxtaposed in a longitudinal direction with a partition wall therebetween, with a sealing paste containing a ceramic powder as a main component. In a method for sealing a body, a mask having an opening formed in a sealing pattern is brought into contact with an end face of the ceramic molded body, and the sealing paste is passed from the opening of the mask to a through hole of the ceramic molded body. A method for sealing a ceramic molded body, comprising: separating the ceramic molded body from the mask while the ceramic molded body is located above the mask after the penetration. 2. A ceramic molding method for sealing an end portion of a through-hole of a columnar ceramic molded body in which a large number of through-holes are juxtaposed in a longitudinal direction with a partition wall therebetween, with a sealing paste containing a ceramic powder as a main component. In a method for sealing a body, a mask having an opening formed in a sealing pattern is brought into contact with an end face of the ceramic molded body, and the sealing paste is passed from the opening of the mask to a through hole of the ceramic molded body. A method of sealing a ceramic molded body, comprising, after the penetration, separating the ceramic molded body and the mask while keeping the mask above the ceramic molded body.