JP6284002B2 - Method for manufacturing ceramic honeycomb structure - Google Patents

Description

  The present invention relates to a method for manufacturing a ceramic honeycomb structure used for purification of harmful substances contained in exhaust gas discharged from an engine such as an automobile.

In order to purify harmful substances contained in exhaust gas discharged from engines such as automobiles, as a catalytic converter for exhaust gas purification using a ceramic honeycomb structure, and a filter for collecting particulate matter discharged from diesel engines, A ceramic honeycomb structure 1 as shown in FIG. 1 is used.
A ceramic honeycomb structure is generally manufactured as follows.
For example, ceramic clay obtained by mixing and kneading ceramic powder such as cordierite-forming raw material powder, binder (organic binder such as methylcellulose), pore-forming agent (organic substance such as graphite), water, etc. is extruded. By extruding through a molding die, a ceramic honeycomb molded body 10 having a honeycomb structure is obtained which is surrounded by the outer peripheral wall 11 and the partition wall 3 and has cells 4 flowing from one end face 5a to the other end face 5b. Next, after drying moisture and the like in the ceramic honeycomb molded body and further removing a molding aid such as a binder in the ceramic honeycomb molded body by a firing furnace, firing at a predetermined temperature to obtain a predetermined shape A high-porosity ceramic honeycomb structure having strength and fine pores in the partition walls is obtained.

As the filter for collecting particulate matter, one having a structure in which one end face 5a and the other end face 5b of the ceramic honeycomb structure are alternately plugged by plugging portions (not shown) is used. Yes. Since the ceramic honeycomb structure used as a filter for collecting particulate matter has a high particulate matter collection rate and low pressure loss characteristics, a ceramic honeycomb structure having a higher porosity is desired. ing. On the other hand, when a large amount of a binder and a pore forming agent are contained in the ceramic clay for the purpose of producing a ceramic honeycomb structure having a high porosity, when the formed body is fired, When cracks occur or in extreme cases, there is a problem that the ceramic honeycomb structure is deformed by its own weight.
As a technique for solving the above problems, Patent Document 1 includes at least an aggregate particle material made of ceramic or metal, water, an organic binder, a pore former, and colloidal particles, and kneaded to form a clay. The clay is formed into a honeycomb shape having a plurality of cells serving as fluid flow paths and dried to obtain a ceramic honeycomb formed body. The formed body is calcined to obtain a calcined body, and then the temporary A method for producing a porous ceramic honeycomb structure is disclosed, wherein a porous ceramic honeycomb structure is obtained by subjecting the fired body to main firing. According to this document, when the molded body is fired, the binder functioning as a reinforcing agent is burned out, and the mechanical strength of the molded body during firing is reduced. In addition, since colloidal particles functioning as a reinforcing agent are contained in the clay, cracks are generated in the porous ceramic honeycomb structure when the molded body is fired, or the porous honeycomb structure is caused by its own weight. It is said that it can effectively prevent the collapse. In Patent Document 1, colloidal particles include specific examples of silica sol, alumina sol, and the like. Therefore, colloidal particles having a diameter in the order of nm (dispersoid) are dispersed in a liquid (dispersion medium). It is shown that.

JP 2004-142978 A

  In the manufacture of the honeycomb molded body described in Patent Document 1, the extruded honeycomb is a honeycomb molded body having an end face shape of 35 mm × 35 mm square and a length of about 152 mm, or a square end face shape of 50 mm × 50 mm square. A honeycomb molded body having a length of about 50 mm. However, as described in Patent Document 1, in the production of a ceramic honeycomb molded body having an outer diameter of 150 mm or more, a porosity of 50% or more, and a high-porosity honeycomb structure, as disclosed in Patent Document 1, When a colloidal solution was mixed and kneaded together with water, an organic binder, and a pore former, and extruded into a honeycomb shape, the following problems occurred. That is, the weight of the aggregate particle raw material and the pore former in the mixing and kneading batch is increased, and the ratio of the pore former to the aggregate particle raw material is increased so that cracks are generated when the ceramic honeycomb formed body is fired. There was a case where the subsequent cracking was remarkable.

  Accordingly, the present invention provides a ceramic honeycomb containing colloidal particles even in the production of a large-sized, high-porosity honeycomb structure having an outer diameter of 150 mm or more and a porosity of 50% or more. A method of manufacturing a ceramic honeycomb structure in which colloidal particles function sufficiently as a reinforcing material after burning and burning of a binder or a pore-forming material when firing a molded body, preventing cracks from being generated, and preventing cracking after firing Is to provide.

  The inventors of the present invention have made intensive studies focusing on the method of mixing colloidal solutions with respect to the problems of the prior art as described above. In other words, when the colloidal solution is mixed and kneaded with water, an organic binder and a pore former, the colloidal particles in the colloidal solution are fine, so in the clay after mixing and kneading, In some cases, the colloidal particles are not uniformly dispersed. Using a clay in which colloidal particles are not uniformly dispersed, extruded into a honeycomb shape, dried, fired, after burning and burning of the binder and pore former when firing the ceramic honeycomb formed body, The function of the colloidal particles as a reinforcing material is not sufficiently exhibited. As a result, when firing the ceramic honeycomb formed body, it was found that cracks could not be prevented and it was difficult to avoid cracks generated after firing, and the present invention was conceived.

Specifically, the present invention includes a mixing step of mixing an aggregate raw material made of ceramics at least with an organic binder, a pore former and water, a kneading step of kneading into clay, and extruding the clay into a honeycomb shape. A method for producing a ceramic honeycomb structure having a ceramic honeycomb structure having an outer diameter of 150 mm or more and a porosity of 50% or more after undergoing a forming step, a drying step for drying, and a firing step for firing, wherein the dispersion is performed in the mixing step. The colloidal solution is composed of silica-based or alumina-based colloidal particles having a solid content and the average particle diameter of the colloidal particles is 10 to 500 nm. It mix | blends by the mass%, The said colloidal solution is sprayed on a mixture, It is characterized by the above-mentioned .

  In the present invention, in the mixing step, A1 / A0 ≧ 0.4 with respect to the cross-sectional area A0 of the mixing tank cross section perpendicular to the rotation axis direction of the rotating blade using a mixer having rotating blades in the mixing tank. The colloidal solution is preferably sprayed onto the mixture in the area A1.

  In the present invention, it is preferable that in the mixing step, after the colloidal solution is sprayed on the mixture, water is further added to perform mixing.

  In the present invention, the aggregate raw material preferably contains at least one component selected from the group consisting of a cordierite forming raw material, mullite, silicon carbide, silicon nitride, alumina, titanium oxide, and aluminum titanate.

  In this invention, it is preferable that the temperature of the clay is 15-60 degreeC in the said kneading | mixing process.

  In the present invention, it is preferable to apply a pressure of 0.1 to 0.5 MPa to the clay in the kneading step.

  In the present invention, it is preferable to perform microwave drying in an atmosphere having a humidity of 70% or more in the drying step.

  In the present invention, the ceramic honeycomb structure preferably has a porosity of 50 to 70%.

  In the present invention, the wall thickness of the ceramic honeycomb structure is preferably 0.1 to 0.5 mm.

  In the present invention, the cell density of the ceramic honeycomb structure is preferably 100 to 300 cells / square inch.

  According to the present invention, a ceramic honeycomb formed body containing colloidal particles also in the production of a large-sized ceramic honeycomb formed body having an outer diameter of 150 mm or more, a porosity of 50% or more, and a high porosity honeycomb structure. The present invention provides a method for manufacturing a ceramic honeycomb structure in which colloidal particles function as a reinforcing material after burning and burning of a binder and a pore former when firing, and cracks can be prevented and cracking hardly occurs after firing. be able to.

The schematic diagram which showed the ceramic honeycomb structure which concerns on this invention. The schematic diagram which showed the state of the mixer which concerns on this invention.

  Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments and is based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Therefore, it should be understood that design changes and improvements can be made as appropriate.

A method for manufacturing the ceramic honeycomb structure of the present invention will be described.
First, in the mixing step, at least an aggregate material made of ceramics, an organic binder, a pore former, and water are mixed. The aggregate raw material can include at least one component selected from the group consisting of cordierite forming raw material, mullite, silicon carbide, silicon nitride, alumina, titanium oxide, and aluminum titanate. In particular, when a ceramic honeycomb structure having an outer diameter of 150 mm or more and a porosity of 50% or more is used, a cordierite-forming raw material having low thermal expansion is preferable.
Cordierite-forming raw material is a raw material that is mixed by firing to have the theoretical composition of cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ), and mainly consists of silica source, magnesia source, and alumina source. The
As the silica source, it is preferable to use at least one member selected from the group consisting of kaolin, talc, quartz, fused silica and amorphous silica.
Moreover, as a magnesia source, it is preferable to use 1 or more types from the group of talc, magnesite, and magnesium hydroxide.
As the alumina source, it is preferable to use one or both of aluminum oxide and aluminum hydroxide.

  The organic binder is an additive that becomes a gel in the molded body after extrusion and maintains the strength of the molded body. As the organic binder, for example, methylcellulose, hydroxypropylmethylcellulose, hydroxypropoxylmethylcellulose, carboxylmethylcellulose, hydroxyethylcellulose, polyvinyl alcohol and the like can be used.

  The pore former is an additive that increases the porosity by forming pores by burning out when the molded body is fired. Examples of the pore former include one kind or one or more kinds such as wheat flour, starch powder, graphite, ceramic balloon, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic, phenol, foamed foamed resin, and unfoamed foamed resin. Can be used in combination. Among these, in order to obtain a ceramic honeycomb structure having a porosity of 50% or more, it is preferable to use a foamed foamed resin.

The colloidal solution is composed of a dispersion medium and colloidal particles (dispersoids) that are solid contents. The colloidal solution is cured by a dehydration condensation reaction or the like at a relatively low temperature, and the aggregated particles are separated even after the binder is burned out. It is an additive that functions as a reinforcing material to be bonded. Colloidal solutions, are use as the dispersion medium, e.g., water, methanol, isopropyl alcohol, dimethyl acetamide, ethylene glycol, methyl ethyl ketone, methyl isobutyl ketone, and one or more such as toluene, shea silica as the colloidal particles, the alumina be able to. Among these, it is preferable to use colloidal silica composed of water as the dispersion medium and silica as the colloidal particles because the bonding between the aggregate particles after burned out binder tends to be good.
The colloidal solution is sprayed on the mixture in which the aggregate raw material, the organic binder, the pore former and water are being mixed to perform mixing, so that the colloidal particles in the colloidal solution are easily mixed into the mixture, and thereafter Even in the clay after being kneaded in the process, colloidal particles are present uniformly. For this reason, colloidal particles function sufficiently as a reinforcing material even after the binder or pore former burns and burns out when extruded into a honeycomb shape using such a clay, dried and fired. As a result, cracks can be prevented in the ceramic honeycomb molded body, cracking hardly occurs after firing, a large-sized ceramic honeycomb structure with an outer diameter of 150 mm or more, a porosity of 50% or more, and a high porosity. You can get a body.
Here, when mixing, any mixer may be used as long as the mixture is uniformly mixed. However, for example, a Henschel mixer having a rotary blade in a cylindrical mixing tank is used. Can do.

The colloidal solution can be sprayed using a spray, a sprayer, or the like. In the mixing machine 20 shown in FIG. 2, the colloidal solution is A1 / A0 ≧ 0.4 with respect to the cross-sectional area A0 of the mixing tank cross section A in the mixing tank cross section A perpendicular to the rotation axis direction of the rotary blade 22 in the mixing tank 21. become in the range of the area A1, Ru is sprayed to the mixture 100 in the mixing tank 21. As a result, the colloidal particles are easily mixed uniformly in the mixture, and the colloidal particles are uniformly present in the clay after being kneaded in the subsequent process. Furthermore, it is preferable to spray the mixture 100 in the mixing tank 21 in the range of area A1 where A1 / A0 ≧ 0.5. In addition, the range of the said area A1 sprayed on the mixture in a mixing tank can be set by changing the space | interval with the spray and sprayer to spray, and a mixture.

  Further, it is preferable to add water and mix after spraying the colloidal solution. This is because, after spraying the colloidal solution, the colloidal particles are further uniformly mixed in the mixture by further adding water and mixing. Thereby, generation | occurrence | production of a crack can be prevented more effectively in a ceramic honeycomb molded object, and the ceramic honeycomb structure which does not generate | occur | produce cracking easily after baking can be obtained.

Then, the average particle diameter of the colloidal particles is 10 to 500 nm, such that easy colloidal particles are uniformly mixed in the mixture. Thereby, generation | occurrence | production of a crack can be prevented more effectively in a ceramic honeycomb molded object, and the ceramic honeycomb structure which does not generate | occur | produce cracking easily after baking can be obtained. When the average particle diameter of the colloidal particles is less than 10 nm, the kneaded clay is easily cured, the extrudability is deteriorated, and cracks are easily generated in the ceramic honeycomb formed body. When firing the ceramic honeycomb formed body cracks occurred, that cracking is liable to occur after firing. On the other hand, when the average particle diameter of the colloid particles exceeds 500 nm, the function of the colloid particles as a reinforcing material is weakened, and when the ceramic honeycomb formed body is fired, the colloid particles are burned and burned out. In some cases, the particles do not sufficiently exhibit the function as a reinforcing material, and the occurrence of cracks in the ceramic honeycomb formed body cannot be prevented. Preferably, it is 15 to 300 nm.

The colloidal solution can make the colloidal particles function as a part of the aggregate raw material. For example, when the aggregate raw material is a cordierite-forming raw material, the mixing ratio of the magnesia source, silica source, and alumina source is adjusted so that the theoretical composition of cordierite is obtained by firing. By using silica-based colloidal particles, the silica source of the cordierite forming raw material is blended in an amount obtained by subtracting the silica component of the colloidal particles. Thereby, the silica component of colloidal particles can be functioned as a part of the cordierite forming raw material which is an aggregate raw material.
In addition, when obtaining an aluminum titanate ceramic using a raw material containing alumina, titanium oxide, and silica as an aggregate raw material, similarly, the colloidal particles are made of silica-based colloidal particles and alumina-based colloidal particles. It can function as a part of the raw material.

Further, colloidal solution, you blended with 0.1 wt% to 10 wt% in solid content with respect to the aggregate material. If it is less than 0.1%, when the ceramic honeycomb formed body is fired, the colloidal particles do not fully function as a reinforcing material after the binder or pore former burns and burns out, and the ceramic honeycomb formed body that that can not be is that of preventing the occurrence of cracks. On the other hand, when it exceeds 10%, colloidal particles with a small particle size increase, so that the kneaded clay becomes too hard, the molding speed of the extrusion molding becomes slow, and the productivity decreases. molding that Do not difficult. Preferably, it is 0.2 mass%-8 mass%.

  Next, in the kneading step, the mixed mixture is kneaded to form a clay. A kneader, a pressure kneader, a vacuum kneader, or the like can be used for kneading, but a ceramic honeycomb that becomes a large-sized, high-porosity honeycomb structure with an outer diameter of 150 mm or more and a porosity of 50% or more. In the production of a molded body, it is preferable to use a pressure kneader that is easily kneaded homogeneously and the pore former is not easily broken by kneading. Kneading while applying a pressure of 0.1 to 0.5 MPa in a pressure kneader is preferable because the colloidal particles in the mixture are more uniformly dispersed. When the pressure is less than 0.1 MPa, the applied pressure is insufficient, and the colloidal particles in the mixture may not be uniformly kneaded, which is not preferable. On the other hand, when the pressure exceeds 0.5 MPa, the pore former is easily broken, and it is difficult to obtain a honeycomb structure with a high porosity having a porosity of 50% or more, which is not preferable. Here, the pressure applied to the pressure kneader is the total of the force pushing the pressure lid of the pressure kneader with the piston shaft, the load on the pressure lid, and the load on the piston shaft, and the area of the material contact surface of the pressure lid The value divided by.

  Further, it is preferable to set the temperature of the clay during kneading to 15 to 60 ° C., since the colloidal particles in the mixture are kneaded more uniformly. When the temperature of the clay is less than 15 ° C., the viscosity of the clay becomes low, and the molded body after extrusion molding tends to be deformed, which is not preferable. On the other hand, when the temperature exceeds 60 ° C., the organic binder is cured and the viscosity of the clay is increased, so that the partition walls of the molded body after extrusion molding are liable to be formed, which is not preferable. Preferably, it is 20-40 degreeC. The temperature of the clay is the average of the values measured at three locations by inserting a thermometer into the clay at the end of kneading.

Next, in the molding process, the kneaded clay is extruded through a mold for extrusion into a honeycomb shape having an outer diameter of 150 mm or more, a wall thickness of 0.1 to 0.5 mm, and a cell density of 100 to 300 cells / square inch. To do.
In the drying step, the extruded ceramic honeycomb formed body is dried. Drying can be performed by hot air drying, microwave drying, dielectric drying, or the like, but it is preferable to perform microwave drying in an atmosphere having a humidity of 70% or more because the entire ceramic honeycomb formed body is uniformly dried.

Next, in the firing step, the dried ceramic honeycomb formed body is fired in an air atmosphere to obtain a ceramic honeycomb structure having an outer diameter of 150 mm or more and a porosity of 50% or more.
In the firing, first, the temperature is raised, and at a temperature of about 150 ° C. to 400 ° C., organic substances such as a binder and a pore former in the ceramic honeycomb formed body are burned and removed. In this temperature range, the rate of temperature rise is preferably 0.2 to 10 ° C./h. At this time, due to combustion of the binder and the pore former, a temperature difference is generated inside and outside the ceramic honeycomb molded body due to combustion heat generation inside the ceramic honeycomb molded body, thereby generating a thermal stress. However, the ceramic honeycomb molded body molded with a clay in which colloidal particles are uniformly kneaded, the colloidal particles in the molded body are fully exerted as a reinforcing material, preventing cracks in the ceramic honeycomb molded body. can do.
The firing conditions for firing the ceramic honeycomb formed body to form a honeycomb structure vary depending on the type of aggregate raw material used. For example, when a cordierite-forming raw material is used, the heating rate is 5 to 20 ° C./h. It is preferable that the maximum temperature is maintained at 1410 to 1450 ° C. and baked for 5 to 15 hours.
The porosity of the fired ceramic honeycomb structure is preferably 50 to 70% in order to have a high particulate matter collection rate and low pressure loss characteristics.

Example 1
As an aggregate material, kaolin with an average particle size of 4.5 μm, talc with an average particle size of 12.5 μm, silica with an average particle size of 38.0 μm, alumina with an average particle size of 6.0 μm, hydroxylation with an average particle size of 12.0 μm Adjust the solid content of the aluminum powder and colloidal solution so that the chemical composition is 51 wt% SiO ₂ , 35 wt% Al ₂ O ₃ , 14 wt% MgO. A raw material A shown in Table 1 was prepared. On the other hand, colloidal silica having a solid content of 20% is used as the colloidal solution, and colloidal silica is prepared in an amount of the amount converted to solid content shown in Table 1 with respect to the cordierite-forming raw material powder. And to this raw material A, 5% by mass of methylcellulose, 2% by mass of hydroxypropylmethylcellulose, 6% by mass of foamed foamed resin and 25% by mass of water as pore formers are added to 100% by mass of the aggregate raw material. Were mixed using a Henschel mixer.
Then, the position of the sprayer is adjusted to the mixture being mixed so that the spray range (A1 / A0) shown in Table 2 is obtained, and the prepared colloidal silica is sprayed with the sprayer, and the aggregate raw material, binder, pore forming Mix material, water and colloidal particles.
Next, the mixture after mixing is put into a pressure kneader, and the pressure applied to the kneaded material is kneaded under the conditions shown in Table 2 to obtain clay. At the end of kneading, a thermometer was inserted into the clay to measure the temperature at three locations, and the average value is shown in Table 2.
Next, the kneaded material was extruded and cut using an extrusion mold, and 20 compacts having a diameter of 270 mm and a length of 300 mm were produced.
Next, the compact was subjected to microwave drying for 20 minutes in an atmosphere with a humidity of 75%, and then fired in an air atmosphere. Firing is performed in a temperature range of 150 to 350 ° C. at a rate of temperature increase of 5 ° C./h, then heated at a rate of temperature increase of 15 ° C./h and calcined at a maximum holding temperature of 1410 ° C. for 12 hours. Twenty cordierite ceramic honeycomb structures of Example 1 having a partition wall thickness of 0.3 mm and a cell pitch of 1.57 mm (260 cells / square inch) were obtained.

The cordierite-type ceramic honeycomb structure of Example 1 thus obtained was measured for formability during extrusion molding, cracking state after firing, and porosity, and are shown in Table 2.
The moldability at the time of extrusion molding is compared with the molding speed at the time of extrusion molding on the basis of the extrusion molding speed in the case of Comparative Example 2 described later without using a colloidal solution.
When it is 80% or more
When it is 50% or more and less than 80%
△ if less than 50%
As evaluated.

The state of cracking was confirmed by visually checking both end faces of the 20 produced ceramic honeycomb structures,
When there are 5 or more cracks
△ When there are 3 to 4 cracks
○ If there are 1-2 cracks
◎ When there is no crack
As evaluated.
The porosity and average pore diameter were measured by a mercury intrusion method by cutting a partition wall sample from one of the 20 produced ceramic honeycomb structures.

(Examples 2 to 10, Reference Examples 1 to 5 )
Example 2 was conducted in the same manner as in Example 1, except that the cordierite-forming raw material powder was blended with raw materials B to G shown in Table 1, and the colloidal solution was colloidal silica having a solid content of 20%. 10 and 20 cordierite ceramic honeycomb structures of Reference Examples 1 to 5 were produced.

(Examples 11 to 12 )
In Example 11 , a raw material B shown in Table 1 was prepared as a cordierite-forming raw material powder as an aggregate raw material, and a raw material F was prepared in Example 12 . On the other hand, colloidal silica having a solid content of 20% is used as the colloidal solution, and colloidal silica is prepared in an amount of the amount converted to solid content shown in Table 1 with respect to the cordierite-forming raw material powder. In Example 11 , the raw material B is used as the raw material B, and in Example 12 , the raw material F is based on 100% by mass of the aggregate raw material, and 5% by mass of methylcellulose as a binder, 2% by mass of hydroxypropylmethylcellulose, Mass% and water 15 mass% were added and mixed using a Henschel mixer.
Then, the position of the sprayer is adjusted so that the spraying range (A1 / A0) shown in Table 2 is applied to the mixture being mixed, and the prepared colloidal silica is sprayed with the sprayer to produce an aggregate raw material, a binder, and a pore former. Mix water and colloidal solution.
Further, 10% by mass of water was further added and mixing was continued.
Next, the mixture after mixing was placed in a pressure kneader, and kneading was performed under the conditions shown in Table 2 with respect to the temperature of the kneaded product and the pressure applied to the kneaded product.
Next, the kneaded material was extruded using an extrusion molding die and cut to produce 20 molded bodies each having a diameter of 270 mm and a length of 300 mm.
Next, the cordierite-type ceramic honeycomb structure of Examples 11 to 12 in which the molded body is dried and fired in the same manner as in Example 1 and the partition wall thickness is 0.3 mm and the cell pitch is 1.57 mm (260 cells / square inch). 20 were prepared for each.

(Example 13 )
In Example 13 , raw materials H shown in Table 1 were prepared as aggregate raw materials: titanium oxide powder having an average particle diameter of 1.5 μm, aluminum oxide powder having an average particle diameter of 2.0 μm, and silica having an average particle diameter of 21.0 μm. On the other hand, colloidal alumina having a solid content of 20% is used as the colloidal solution, and colloidal alumina is prepared in an amount of the amount converted to solid content shown in Table 1 with respect to the aggregate raw material powder. To this raw material H, 5% by mass of methylcellulose, 2% by mass of hydroxypropylmethylcellulose, 10% by mass of foamed foamed resin and 25% by mass of water as a pore former are added to 100% by mass of the aggregate raw material. Mix using a Henschel mixer.
Then, the position of the sprayer is adjusted so that the spraying range (A1 / A0) shown in Table 2 is applied to the mixture being mixed, and the prepared colloidal alumina is sprayed with the sprayer to produce an aggregate raw material, a binder, and a pore former. Mix water and colloidal solution.
Next, the mixture after mixing was placed in a pressure kneader, and kneading was performed under the conditions shown in Table 2 with respect to the temperature of the kneaded product and the pressure applied to the kneaded product.
Next, the kneaded material was extruded using an extrusion mold and cut to produce 20 molded bodies each having a diameter of 152 mm and a length of 152 mm.
Next, the compact was subjected to microwave drying for 20 minutes in an atmosphere with a humidity of 75%, and then fired in an air atmosphere. Firing is performed in a temperature range of 150 to 350 ° C. at a rate of temperature increase of 5 ° C./h, then heated at a rate of temperature increase of 20 ° C./h and fired at a maximum holding temperature of 1600 ° C. for 10 hours. Twenty aluminum titanate ceramic honeycomb structures of Example 13 having a partition wall thickness of 0.3 mm and a cell pitch of 1.57 mm (260 cells / square inch) were produced.

(Comparative Example 1)
As an aggregate raw material, a cordierite-forming raw material powder is blended with the raw material B shown in Table 1. Based on 100% by mass of the aggregate raw material, 5% by mass of methylcellulose, 2% by mass of hydroxypropylmethylcellulose, a pore former As a colloidal silica, 6% by mass of foamed foamed resin, 25% by mass of water, and 20% solid content as a colloidal solution were blended in the ratio shown in Table 1 with respect to the cordierite-forming raw material powder. The colloidal solution was added without spraying and mixed with these raw materials.
Next, the mixture after mixing was placed in a pressure kneader, and kneading was performed under the conditions shown in Table 2 with respect to the temperature of the kneaded product and the pressure applied to the kneaded product.
Next, the kneaded material was extruded and cut using an extrusion mold, and 20 compacts having a diameter of 270 mm and a length of 300 mm were produced.
Next, the molded body was dried and fired in the same manner as in Example 1, and a cordierite ceramic honeycomb structure of Comparative Example 1 having a partition wall thickness of 0.3 mm and a cell pitch of 1.57 mm (260 cells / in 2) was prepared. Individually produced.

(Comparative Example 2)
As an aggregate material, kaolin with an average particle size of 4.5 μm, talc with an average particle size of 12.5 μm, silica with an average particle size of 38.0 μm, alumina with an average particle size of 6.0 μm, hydroxylation with an average particle size of 12.0 μm The raw material I of the cordierite-forming raw material powder shown in Table 1 is prepared by adjusting the aluminum powder so that the chemical composition is 51% by mass of SiO ₂ , 35% by mass of Al ₂ O ₃ and 14% by mass of MgO. The formulation was as follows. Then, to 100% by mass of the aggregate material, 5% by mass of methylcellulose, 2% by mass of hydroxypropylmethylcellulose, 6% by mass of foamed foamed resin as a pore former, and 25% by mass of water are added to the raw material I. Mixed and no colloidal solution was used.
Next, the mixture after mixing was placed in a pressure kneader, and kneading was performed under the conditions shown in Table 2 with respect to the temperature of the kneaded product and the pressure applied to the kneaded product.
Next, the kneaded material was extruded and cut using an extrusion mold, and 20 compacts having a diameter of 270 mm and a length of 300 mm were produced.
Next, the molded body was dried and fired in the same manner as in Example 1, and the cordierite ceramic honeycomb structure of Comparative Example 2 having a partition wall thickness of 0.3 mm and a cell pitch of 1.57 mm (260 cells / in 2) was prepared. Individually produced.

As shown in Table 2, the ceramic honeycomb structures of Examples 1 to 13 of the present invention have a large and high porosity with an outer diameter of 150 mm or more and a porosity of 50% or more. It can be seen that the occurrence of cracks is small. On the other hand, in the ceramic honeycomb structure of Comparative Example 1, since the colloidal solution was mixed at the same time with the cordierite forming raw material during mixing, there was a portion where the colloidal particles were not uniformly mixed in the mixture. There were many. In Comparative Example 2, since colloidal particles were not used, cracking occurred frequently after firing.

1: Ceramic honeycomb structure 3: Partition wall 4: Cell 5a, 5b: End face 10: Ceramic honeycomb molded body 11: Outer peripheral wall 100: Mixture 20: Mixer 21: Mixing tank 22: Rotary blade 23: Spray

Claims (10)

A mixing step of mixing at least an aggregate material made of ceramics and an organic binder, a pore former and water, a kneading step to knead to form clay, a molding step to extrude the clay into a honeycomb shape, and a drying step to dry A method for producing a ceramic honeycomb structure having a ceramic honeycomb structure having an outer diameter of 150 mm or more and a porosity of 50% or more after a firing step of firing, wherein the mixture includes a dispersion medium and a solid content in the mixing step. A colloidal solution composed of a certain silica-based or alumina-based colloidal particle and having an average particle diameter of 10-500 nm of the colloidal particle is blended in a solid content of 0.1 mass% to 10 mass% with respect to the aggregate raw material. And spraying the ceramic honeycomb structure. In the mixing step, a mixer having a rotating blade in the mixing tank is used, and an area A1 in which A1 / A0 ≧ 0.4 with respect to the cross-sectional area A0 of the mixing tank cross section perpendicular to the rotation axis direction of the rotating blade. The method for manufacturing a ceramic honeycomb structure according to claim 1, wherein the colloidal solution is sprayed onto the mixture. 3. The method for manufacturing a ceramic honeycomb structure according to claim 1, wherein in the mixing step, after the colloidal solution is sprayed on the mixture, water is further added to perform mixing. 2. The aggregate raw material includes at least one component selected from the group consisting of cordierite forming raw material, mullite, silicon carbide, silicon nitride, alumina, titanium oxide, and aluminum titanate. A method for manufacturing a ceramic honeycomb structure according to any one of claims 3 to 3 . The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 4 , wherein a temperature of the clay is 15 to 60 ° C in the kneading step. The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 5 , wherein a pressure of 0.1 to 0.5 MPa is applied to the clay in the kneading step. The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 6 , wherein in the drying step, microwave drying is performed in an atmosphere having a humidity of 70% or more. The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 7 , wherein a porosity of the ceramic honeycomb structure is 50 to 70%. The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 8 , wherein a wall thickness of the ceramic honeycomb structure is 0.1 to 0.5 mm. The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 9 , wherein a cell density of the ceramic honeycomb structure is 100 to 300 cells / in 2.

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