JP2008056528A - Slurry for plug stuffing and method for manufacturing plug-stuffed honeycomb - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide slurry for plug stuffing which can plug to a specified depth, with no gap, and so as to have excellent thermal shock properties, when plugging into a cell of the honeycomb, and to provide a method for manufacturing a plug-stuffed honeycomb. <P>SOLUTION: The slurry 1 for plug stuffing comprising an outer skin, porous cell walls which are arranged in a honeycomb shape inside the outer skin, a cordierite material having many rectangular cells which are partitioned within the cell walls and are formed along the axial direction is used in the case of plugging into the cell of the honeycomb. The slurry for plug stuffing comprises aggregate 2, a dispersing agent 3 and water 4. The aggregate 2 includes a ceramic powder which forms cordierite crystals by sintering. The particle diameter of the ceramic powder is 6-22 μm (D50 regulation). The contact angle of the slurry 1 for plug stuffing is ≤114° when adhering to the cell wall. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plugging slurry and a method for manufacturing a plugged honeycomb body.

  Ceramic honeycomb bodies are widely used as a carrier for automobile exhaust gas purification catalysts. As a method for forming a honeycomb formed body, extrusion molding or plunger molding is generally used. In the case of producing by extrusion molding, the kneaded raw material can be produced by extrusion molding using a mold, followed by drying and baking.

  Further, the honeycomb body includes a plugged honeycomb body in which the opening end portions of the cells are plugged. The plugged honeycomb body can be manufactured, for example, by extruding the kneaded raw material using a mold, followed by drying, temporary firing, masking, plugging, and firing.

  Conventionally, in plugging a honeycomb body, when plugging a cell opening end portion surrounded by a cell wall of the honeycomb body, it has been difficult to plug the cell body to a desired depth without a gap.

JP 2002-37672 A

  The present invention has been made in view of such a conventional problem, and when plugging cells of a honeycomb body, the plugging is performed so as to have excellent thermal shock resistance without gaps to a predetermined depth. An object of the present invention is to provide a plugging slurry and a method for producing a plugged honeycomb body.

According to a first aspect of the present invention, there is provided an outer skin, a porous cell wall disposed in a honeycomb shape in the outer skin, and a large number of quadrangular cells partitioned in the cell wall and formed along the axial direction. Having a plugging slurry used for plugging the cells of the honeycomb body made of cordierite blended raw material,
Contains at least aggregate, dispersant, and water,
The aggregate contains a ceramic powder that becomes cordierite crystals by firing,
The particle size of the ceramic powder is 6 to 22 μm (D50 regulation),
The plugging slurry is in the plugging slurry having a contact angle of 114 ° or less when adhering to the cell wall (Claim 1).

The most notable point of the present invention is that the plugging slurry used for plugging the rectangular cells of the honeycomb body has a particle diameter of 6 to 22 μm and is fired to produce cordierite crystals. The ceramic powder becomes an essential component, and the contact angle when the plugging slurry adheres to the cell wall is 114 ° or less.
Thereby, it can plug up so that it may have the outstanding thermal shock property without a clearance gap to predetermined depth.

  That is, by using ceramic powder that becomes cordierite crystals by firing in the aggregate, the honeycomb body and the plugging slurry can be sintered and joined at the time of firing, There is no difference in the thermal expansion of the plugging slurry, and the thermal shock resistance of the resulting plugged honeycomb body can be improved.

Moreover, by regulating the particle size of the ceramic powder to 6 to 22 μm (D50 regulation), shrinkage due to crystallization can be suppressed when firing the plugging slurry. Therefore, the difference in shrinkage ratio during firing is reduced, and the formation of gaps after plugging can be suppressed.
The “D50 regulation” is a regulation that defines the distribution range to which the D50 belongs, with D50 being the 50% frequency from the lowest in the particle size distribution. “D50 regulation” in the present invention is 14 ± 8 μm.

The plugging slurry has a contact angle of 114 ° or less when adhered to the cell wall. Thereby, when plugging into the cells of the honeycomb body, the plugging slurry can be arranged without gaps.
That is, in the honeycomb body of the present invention, the cells have a quadrangular shape and the four corners are 90 °. The plugging slurry has a contact angle with the cell wall of 114 ° or less and has appropriate wettability. Therefore, the plugging slurry reaches the four corners of the cell and can be arranged without gaps.

  Thus, according to the present invention, in order to limit the essential components, further limit the particle size, and limit the contact angle of the plugging slurry, when plugging the cells of the honeycomb body, It is possible to provide a plugging slurry that can be plugged so as to have excellent thermal shock resistance without a gap to a predetermined depth.

According to a second aspect of the present invention, there is provided an outer skin, a porous cell wall disposed in a honeycomb shape in the outer skin, and a large number of quadrangular cells partitioned in the cell wall and formed along the axial direction. A method for producing a plugged honeycomb body in which the cells of the honeycomb body made of cordierite blended raw material are plugged with a plugging slurry,
A substrate having a honeycomb structure is extruded, dried, cut to a predetermined length, and a plurality of cell walls provided in a honeycomb shape and partitioned by the cell walls and penetrating through both end faces. An extrusion molding process for producing a honeycomb formed body having cells;
Calcining the honeycomb formed body to form a honeycomb body; and
A masking step of opening a portion to be plugged among the openings of the cells on the end face of the honeycomb body and arranging a masking material so as to cover the other portions;
A plugging step in which a plugging slurry is disposed in the portion to be plugged;
A firing step of firing the honeycomb body and the plugging slurry simultaneously,
In the plugging process, the plugging slurry according to any one of claims 1 to 5 is used as the plugging slurry. (Claim 6) ).

  As described above, the manufacturing method of the plugged honeycomb body of the present invention uses the plugging slurry described in the first invention as the plugging slurry in the plugging process in manufacturing the plugged honeycomb body. ing. Therefore, the plugged honeycomb body obtained is plugged so as to have an excellent thermal shock property without a gap to a predetermined depth.

  In the manufacturing method of the plugged honeycomb body, the contraction of the honeycomb formed body is almost completed in the temporary firing step. The plugging slurry described in the first invention used as the plugging slurry can be disposed without gaps as described above, and has a small shrinkage due to crystallization when fired. Therefore, in the firing step, the difference between the shrinkage rate of the honeycomb body and the shrinkage rate of the plugging slurry is reduced, and the formation of gaps after plugging can be suppressed.

  Thus, according to the present invention, when plugging the cells of the honeycomb body, there is provided a method for manufacturing a plugged honeycomb body that can be plugged so as to have excellent thermal shock without gaps up to a predetermined depth. Can be provided.

As described above, the plugging slurry of the first invention contains at least an aggregate, a dispersant, and water.
The aggregate contains a ceramic powder that becomes cordierite crystals when fired.
Examples of the ceramic powder include silica (SiO ₂ ), talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), aluminum hydroxide (Al (OH) ₃ ), and alumina (Al ₂ O ₃ ). It is done.

  Examples of the dispersant include ammonium polycarboxylate, polycarboxylic acid copolymer, ammonium polyacrylate, and sodium polyacrylate.

The particle size of the ceramic powder is 6 to 22 μm (D50 regulation).
When the particle size of the ceramic powder is less than 6 μm, there is a problem that the shrinkage rate is too large during the firing and a gap is generated. On the other hand, when the particle size exceeds 22 μm, the coarse ceramic powder in the slurry easily settles, and the fine ceramic powder is plugged into the cell, resulting in a gap as described above. There is a problem.

The plugging slurry has a contact angle of 114 ° or less when adhered to the cell wall. Thereby, as above-mentioned, the plugging slurry can be arrange | positioned without gap to the four corners of a square-shaped cell.
When the contact angle exceeds 114 °, there is a problem that gaps are generated at the four corners of the cell.

The plugging slurry of the first invention preferably has a contact angle of 58 ° or more when adhered to the cell wall (claim 2).
In this case, the plugging slurry can be plugged uniformly in the plug depth direction.
If the contact angle is less than 58 °, the plug depth may be too deep, or the plug depth may vary depending on cell shape variation.

The contact angle between the plugging slurry and the cell wall can be adjusted by adjusting the viscosity of the plugging slurry, the surface properties of the cell wall, and the like.
The viscosity of the plugging slurry can be adjusted by, for example, the content of the dispersant. The surface properties of the cell wall can be adjusted, for example, by forming a water-soluble film on the surface of the cell wall, as will be described later.

Moreover, it is preferable that the content rate of the said dispersing agent is 0.3-1.0 wt% S / S by solid content ratio with respect to the said aggregate.
When the content of the dispersing agent is less than 0.3 wt%, the viscosity of the plugging slurry becomes high, which may make plugging difficult. On the other hand, when the content of the dispersant exceeds 1.0 wt%, the effect is not improved, and the dispersibility of the plugging slurry may be lowered.

The plugging slurry contains a binder, and the binder content is preferably 0.5 wt% S / S or less in terms of solid content with respect to the aggregate. 4).
When the content of the binder exceeds 0.5 wt% S / S, the viscosity of the plugging slurry becomes high, which may make plugging difficult, and consequently the strength of the plugging material decreases. There is a fear.
Examples of the binder include methyl cellulose, polyvinyl alcohol, and agar.

The water content is preferably 30 to 45 wt% (internal addition) when the entire plugging slurry is 100 wt% (Claim 5).
When the water content is less than 30 wt%, the viscosity increases and plugging may be difficult. On the other hand, when the content rate of water exceeds 45 wt%, the central portion of the plug portion may be concave, and in some cases, a hole may be formed.

In the method for manufacturing a plugged honeycomb body according to the second invention, the honeycomb body forms a water-soluble film in advance on the surface of the cell wall including at least the portion to be plugged before the plugging step. (Claim 7).
In this case, the contact angle between the plugging slurry and the cell wall can be easily reduced to 114 ° or less by improving the surface properties of the cell wall. Therefore, the plugging slurry can be stably plugged in the plugging process.
Examples of the water-soluble film include methyl cellulose, polyvinyl alcohol, and agar.

(Example 1)
In this example, an embodiment according to the present invention will be described with reference to FIG.
As shown in FIG. 1, the plugging slurry 1 of this example contains at least an aggregate 2, a dispersant 3, and water 4.
The aggregate 2 contains a ceramic powder that becomes cordierite crystals when fired, and the ceramic powder has a particle size of 6 to 22 μm.
This will be described in detail below.

In this example, as examples of the present invention, slurry for plugging (sample E1, sample E2) having the composition shown in Table 1 was prepared, and as a comparative example of the present invention, for plugging having the composition shown in Table 1. Slurries (Sample C1 to Sample C3) were prepared. Further, as a sample C4, a plugging slurry made of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) not having a cordierite blend composition was prepared.
The plugging slurry was prepared by putting aggregate, water, dispersant, and binder in a 5 L pot and mixing at 60 rpm for 12 to 48 hours.

In Table 1, silica (SiO ₂ ) is used as the raw material A, talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ) is used as the raw material B, and aluminum hydroxide (Al (OH) is used as the raw material C. ₃ ) and alumina (Al ₂ O ₃ ) was used as the raw material D.
In addition, ammonium polycarboxylate was used as the dispersant, and methylcellulose was used as the binder.

  Moreover, in Table 1, the content rate of a dispersing agent and a binder is shown by the solid content ratio with respect to the said aggregate, and the content rate of water is content rate (internal addition) when the whole slurry for plugging is 100 wt%. Indicated.

Next, using the plugging slurry obtained, the contact angle and the particle size of the ceramic powder were measured.
<Contact angle measurement test>
As shown in FIG. 2, the contact angle was measured by dropping the prepared plugging slurry 1 onto a base material 7 containing cordierite as a main component and measuring the contact angle θ. The base material 7 is obtained by processing the cell walls of a honeycomb body manufactured in the same manner as the honeycomb body shown in Example 2 described later into a plate shape. No water-soluble film or the like is formed on the surface. A case where the evaluation is ◎ and ○ is a pass, and a case where the evaluation is × is a failure.
(Evaluation criteria)
A: When the contact angle is 58 to 114 °.
○: When the contact angle is less than 58 °.
X: When a contact angle exceeds 114 degrees.

<Particle size measurement test>
The particle size of the ceramic powder was measured using a Nikkiso particle size distribution measuring device (Microtrac). The case where evaluation is (circle) is a pass, and the case where evaluation is x is disqualified.
(Evaluation criteria)
○: When the particle diameter is 6 to 22 μm.
X: When the particle diameter is less than 6 μm or more than 22 μm.

As is known from Table 2, Samples E1 and E2 as examples of the present invention showed good results in both items of contact angle and particle size.
Further, the contact angle of Sample C1 as a comparative example of the present invention exceeded the upper limit of the present invention.
Sample C2 as a comparative example of the present invention had a particle size below the lower limit of the present invention.
Sample C3 as a comparative example of the present invention had a particle size exceeding the upper limit of the present invention.
Sample C4 as a comparative example of the present invention is not a cordierite blend composition.

(Example 2)
In this example, an example according to the method for manufacturing a honeycomb body of the present invention will be described.
The manufacturing method of the honeycomb body of the present example includes an extrusion molding process, a temporary firing process, a masking process, a plugging process, and a firing process.
In this example, as shown in FIG. 5, an outer skin 63, a porous cell wall 61 disposed in a honeycomb shape in the outer skin 63, and a partition formed in the cell wall 61 and formed along the axial direction. This is an example in which a plugged honeycomb body 6 in which the cells 62 of the honeycomb body made of cordierite blended raw material having a large number of quadrangular cells 62 are plugged with a plugging slurry 1 is produced.
This will be described in detail below.

The honeycomb body before plugging of the plugged honeycomb body 6 manufactured according to this example is mainly composed of cordierite having a theoretical composition represented by 2MgO · 2Al ₂ O ₃ · 5SiO _2. . Usually, cordierite, the SiO ₂ from 49.0 to 53.0 wt%, the Al ₂ O ₃ 33.0 to 37.0 wt%, containing MgO in a proportion of 11.5 to 15.5 wt% To do.

As the raw material of the honeycomb body, a cordierite blending raw material adjusted to have a desired cordierite composition and a molding aid added and kneaded is used. Examples of the cordierite blending raw material include silica (SiO ₂ ), talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), aluminum hydroxide (Al (OH) ₃ ), and alumina (Al ₂ O ₃ ). Further, Mg source, Al source, Si source oxide, hydroxide, chloride and the like can be used. For example, carion (Al ₂ Si ₂ O ₅ (OH) ₄ ), serpentine (Mg ₃ Si ₂ O ₅ (OH) ₄ ), pyroferrite (Al ₂ Si ₄ O ₁₀ (OH) ₂ ), brucite (Mg (OH) ₂ ) and the like.

  Further, as a molding aid added to the cordierite blending raw material, commonly used lubricants, humectants, binders, and the like can be used. Examples of lubricants and humectants include waxes, water-soluble polyhydric alcohol derivatives, and surfactants. Examples of the binder include methyl cellulose, polyvinyl alcohol, and agar.

First, the cordierite blending raw material and a molding aid were kneaded to obtain a raw material.
In the extrusion molding step, the raw material is extruded, dried, cut to a predetermined length, and partitioned by the cell walls 61 and penetrating both end faces. A honeycomb formed body having a plurality of rectangular cells 62 was prepared. The extrusion conditions are an extrusion pressure of 100 to 200 kg / cm ² , an extrusion speed of 1.0 to 2.0 m / min, and a raw material temperature of 10 to 20 ° C.

Further, in the temporary firing step, the honeycomb formed body was temporarily fired to form a honeycomb body. Pre-baking was performed under the condition of holding at 1400 ° C for 1 hour. Thereby, the contraction of the honeycomb body is almost completed.
Next, in the masking step, a masking material was disposed so as to open a portion to be plugged in the opening portion of the cell 62 on the end face of the honeycomb body and cover the other portion.

Thereafter, in the plugging process, the honeycomb body was dipped in the plugging slurry, so that the plugging slurry 1 which is the material of the plug portion was disposed in the portion to be plugged.
In the plugging step of this example, the plugging slurry (sample E1, sample E2, and samples C1 to C4) prepared in Example 1 was used as the plugging slurry 1.

Thereafter, in the firing step, the honeycomb body and the plugging slurry were fired simultaneously. Firing was performed under the condition of holding at 1430 ° C. for 30 hours.
Thereby, the plugged honeycomb body 6 was obtained.

Next, the following evaluation test was performed using the plugged honeycomb body 6 obtained.
<Gap test>
The gap was evaluated by conducting a light transmission test on the honeycomb body and confirming the presence or absence of the gap.
FIG. 3A shows the result of the sample E1, and FIG. 3B shows the result of the sample C1.
Moreover, the sample E2, the sample C3, and the sample C4 were plugged up to the four corners of the cell without a gap, similarly to the result of the sample E1.
Further, in the sample C2, as in the result of the sample C1, gaps 64 were confirmed at the four corners of the cell.

<Plug depth test>
The plug depth was measured by photographing and observing the cross-sectional plug shape by X-ray CT.
FIG. 4A shows the results of samples C1 and C2, FIG. 4B shows the results of sample E1, and FIG. 4C shows the results of samples E2, C3, and C4.

<Thermal shock resistance>
For the thermal shock resistance, the plugged honeycomb body 6 was placed in an electric furnace at 650 ° C. for 20 minutes and then taken out into the air at room temperature to evaluate whether the plugged honeycomb body was cracked. Those with an evaluation of ○ are passed, and those with an evaluation of × are rejected. The results are shown in Table 2.
(Evaluation criteria)
○: When no crack occurs in the plugged honeycomb body.
X: When a crack occurs in the plugged honeycomb body.

As is known from FIGS. 3 and 4, the sample E1 as an example of the present invention showed good results in both items of the gap and the plug depth.
Moreover, although sample E2 as an example of the present invention could be plugged up to a predetermined depth without a gap, variation in plug depth was seen compared to Example 1. Thereby, it turns out that 58-114 degrees are more preferable as a contact angle at the time of adhering to the cell wall of the slurry for plugging.

Moreover, since the contact angle exceeded the upper limit of this invention, the sample C1 as a comparative example of this invention was not able to be plugged up to a predetermined depth without a gap.
Further, the sample C2 as a comparative example of the present invention has a ceramic powder having a particle size below the lower limit of the present invention. There has occurred.

Further, the sample C3 as a comparative example of the present invention is a slurry having a high moisture content because the particle size of the ceramic powder exceeds the upper limit of the present invention, so that the settling speed of the aggregate in the slurry is increased. Entered the cell, and the central part of the stopper became concave. In some cases, there may be a hole.
Moreover, since the sample C4 as a comparative example of the present invention is not a ceramic blend composition that becomes cordierite crystals when fired on the aggregate, the thermal shock resistance is unacceptable.

As described above, by regulating the particle size of the ceramic powder to 6 to 22 μm (D50 regulation), shrinkage due to crystallization can be suppressed when the plugging slurry is fired. Therefore, the difference in shrinkage ratio during firing is reduced, and the formation of gaps after plugging can be suppressed.
Thus, according to the plugging slurry and honeycomb body manufacturing method of the present invention, it is possible to obtain a plugged honeycomb body that is plugged so as to have excellent thermal shock resistance without a gap to a predetermined depth. .

FIG. 3 is an explanatory diagram showing a plugging slurry in Example 1. FIG. 3 is an explanatory diagram showing a contact angle evaluation test in Example 1. Sectional drawing which shows the clearance gap evaluation test in Example 2. FIG. Sectional drawing which shows the plug depth evaluation test in Example 2. FIG. FIG. 6 is an explanatory view showing a honeycomb body in Example 2.

Explanation of symbols

1 Slurry for plugging 2 Aggregate 3 Dispersant 4 Water

Claims (7)

Cordierite blend having an outer skin, a porous cell wall disposed in a honeycomb shape in the outer skin, and a large number of quadrangular cells partitioned in the cell wall and formed along the axial direction A plugging slurry used for plugging the cells of the honeycomb body made of a raw material,
Contains at least aggregate, dispersant, and water,
The aggregate contains a ceramic powder that becomes cordierite crystals by firing,
The particle size of the ceramic powder is 6 to 22 μm (D50 regulation),
The plugging slurry has a contact angle of 114 ° or less when adhered to the cell wall.   The plugging slurry according to claim 1, wherein the contact angle is 58 ° or more.   3. The plugging slurry according to claim 1, wherein the content of the dispersing agent is 0.3 to 1.0 wt% S / S in terms of solid content with respect to the aggregate.   The slurry according to any one of claims 1 to 3, wherein the slurry contains a binder, and the binder content is 0.5 wt% S / S or less in terms of solid content with respect to the aggregate. A slurry for plugging, characterized in that there is.   The plugging slurry according to any one of claims 1 to 4, wherein the water content is 30 to 45 wt% (internal addition) when the entire plugging slurry is 100 wt%. . Cordierite blend having an outer skin, a porous cell wall disposed in a honeycomb shape in the outer skin, and a large number of quadrangular cells partitioned in the cell wall and formed along the axial direction A method for producing a plugged honeycomb body in which the cells of the honeycomb body made of a raw material are plugged with a plugging slurry,
A substrate having a honeycomb structure is extruded, dried, cut to a predetermined length, and a plurality of cell walls provided in a honeycomb shape and partitioned by the cell walls and penetrating through both end faces. An extrusion molding process for producing a honeycomb formed body having cells;
Calcining the honeycomb formed body to form a honeycomb body; and
A masking step of opening a portion to be plugged with the plugging slurry and opening a masking material so as to cover the other portion of the opening of the cell on the end face of the honeycomb body; and
A plugging step in which a plugging slurry is disposed in the portion to be plugged;
A firing step of firing the honeycomb body and the plugging slurry simultaneously,
In the plugging step, the plugging slurry according to any one of claims 1 to 5 is used as the plugging slurry.   7. The plugged honeycomb body according to claim 6, wherein the honeycomb body is formed with a water-soluble film in advance on the surface of the cell wall including at least the portion to be plugged before the plugging step. Production method.

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