JP5001892B2 - Manufacturing method of honeycomb structure - Google Patents

Description

  The present invention relates to a method for manufacturing a honeycomb structure, and more particularly to a method for manufacturing a honeycomb structure having excellent formability and a low thermal expansion coefficient of the obtained honeycomb structure.

A catalyst that supports NO _x , CO, HC, etc. in the exhaust gas to collect dust and other particulate matter contained in incineration exhaust gas generated during incineration of automobile exhaust gas and waste In order to adsorb and purify by a honeycomb structure, a honeycomb structure made of ceramics is used. Among such honeycomb structures, cordierite honeycomb structures are used as those having excellent thermal shock resistance.

  As a method for producing such a cordierite honeycomb structure, for example, a ceramic raw material (cordierite raw material), water, an organic binder, etc. are kneaded, and a clay with improved plasticity is extruded, dried, Examples include a method for producing a ceramic structure to be fired. When extruding a clay containing a ceramic raw material, a certain degree of fluidity is required for the clay to improve formability, but by adding a fine layered mineral such as smectite to the clay, A method for improving the fluidity of the clay and improving the moldability is disclosed (for example, see Patent Documents 1 to 4).

Further, it is known that when the ceramic raw material contains a large amount of impurities such as sodium, calcium and potassium, the thermal expansion coefficient of the resulting honeycomb structure increases. On the other hand, by incorporating boehmite (alumina monohydrate) fine particles having a low content of these impurities into the clay, the moldability of the clay is improved and the thermal expansion coefficient of the resulting honeycomb structure is increased. A method of reducing is disclosed (for example, see Patent Document 5).
International Publication No. WO2005 / 94967 Pamphlet International Publication No. WO2005 / 97703 Pamphlet International Publication No. WO2005 / 102963 Pamphlet International Publication No. WO2006 / 46542 Pamphlet JP 2006-256908 A

  Fine layered minerals such as smectite are generally natural minerals and have a problem that they contain a large amount of impurities such as sodium, calcium and potassium. Further, the method of adding boehmite fine particles to the kneaded clay contributes to improving the moldability of the kneaded clay to some extent because the kneaded clay added with the boehmite fine particles tends to increase in hardness. However, since this method requires a large amount of added water, there is a problem that the shrinkage rate when drying and firing the honeycomb molded body obtained by molding the kneaded clay is high, and the dimensional stability is poor. there were. In addition, if coarse silica (crystalline) is present when the honeycomb formed body is dried and fired, the timing of shrinkage at the time of firing is delayed, so that the shrinkage rate at the time of drying and firing can be reduced, and dimensional variation can be suppressed. . Therefore, a method of adding boehmite fine particles and coarse silica (crystalline) to the clay is conceivable. However, in this method, since the particle size of the coarse silica is large, the porosity and the pore diameter of the obtained honeycomb structure are considered. There is a problem that becomes large and the strength is insufficient.

  The present invention has been made in view of such problems of the prior art, and provides a method for manufacturing a honeycomb structure having excellent formability and a low thermal expansion coefficient of the obtained honeycomb structure. And

  The present invention provides the following method for manufacturing a honeycomb structure.

[1] the cordierite forming raw material, sodium, total content of calcium and potassium 0.05 wt% or less, an average particle diameter of 0.10 [mu] m or less of the alumina particles, sodium, total content of calcium and potassium Is added with silica particles having an average particle diameter of 0.10 μm or less as a molding aid to form a clay, and the content of the molding aid in the clay is It is 2 to 10% by mass with respect to the total amount of the cordierite forming raw material and the molding aid. The obtained clay is molded into a honeycomb shape to produce a honeycomb molded body, and the honeycomb molded body is fired. A honeycomb structure manufacturing method for obtaining a honeycomb structure.

[ 2 ] The method for manufacturing a honeycomb structured body according to [1 ], wherein a mixing ratio of the alumina particles and the silica particles in the clay is alumina particles: silica particles = 10: 1 to 1:30.

[ 3 ] The method for manufacturing a honeycomb structured body according to [1] or [2] , wherein the silica particles are amorphous silica.

[ 4 ] The method for manufacturing a honeycomb structure according to any one of [1] to [ 3 ], wherein 30 to 50% by mass of water is contained in the clay in the entire clay.

  According to the method for manufacturing a honeycomb structure of the present invention, alumina particles having an average particle diameter of 1.0 μm or less and silica particles having an average particle diameter of 1.0 μm or less are formed in the clay used for forming the honeycomb formed body. Since it contains as an auxiliary agent, the fluidity of the clay is improved and the moldability is improved. At the same time, the dimensional stability and strength required for the honeycomb structure can be ensured. Further, the total content of sodium, calcium and potassium in the alumina particles is 0.05% by mass or less, and the total content of sodium, calcium and potassium in the silica particles is 0.05% by mass or less. Therefore, the thermal expansion coefficient of the obtained honeycomb structure can be lowered, and the thermal shock resistance can be improved.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be specifically described. However, the present invention is not limited to the following embodiment, and is within the scope of the gist of the present invention. Based on this knowledge, it should be understood that design changes, improvements, etc. can be made as appropriate.

  One embodiment of a method for manufacturing a honeycomb structure of the present invention contains a cordierite forming raw material, and further, the total content of sodium, calcium and potassium is 0.05% by mass or less, and the average particle size is 1.0 μm or less. A clay containing the alumina particles and silica particles having a total content of sodium, calcium and potassium of 0.05% by mass or less and an average particle size of 1.0 μm or less as a molding aid is formed into a honeycomb shape. A honeycomb formed body is manufactured, and the manufactured honeycomb formed body is fired to obtain a honeycomb structure. Here, the honeycomb structure is a cylindrical structure having porous partition walls that define a plurality of cells.

(Soil)
In one embodiment of the method for manufacturing a honeycomb structure of the present invention, first, a cordierite forming raw material and a forming aid are mixed and kneaded to form a clay. As molding aids, alumina particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 0.05% by mass or less and an average particle size of 1.0 μm or less, sodium and calcium And silica particles having a total content of potassium (alkali metal / alkaline earth metal content) of 0.05% by mass or less and an average particle size of 1.0 μm or less are used. The cordierite-forming raw material means a raw material that becomes cordierite by firing. Silica (SiO ₂ ) is 42 to 56 mass%, alumina (Al ₂ O ₃ ) is 30 to 45 mass%, and magnesia (MgO) is 12 A ceramic raw material in which a predetermined raw material is mixed so as to have a chemical composition (hereinafter referred to as a “cordierite composition range”) in a range of ˜16% by mass. As a suitable composition of cordierite, 2MgO · 2Al ₂ O ₃ · 5SiO ₂ can be exemplified. In this embodiment, examples of the “predetermined raw material” to be mixed to form the cordierite forming raw material include talc, kaolin, alumina source raw material (alumina, aluminum hydroxide, boehmite, etc.), silica, and the like. . The cordierite forming raw material alumina / silica has a molding auxiliary effect so as to satisfy the condition of “alkali metal / alkaline earth metal content 0.05 mass% or less, average particle diameter 1.0 μm or less”. In this case, however, the content of the molding aid often exceeds the preferred range described later. Therefore, it is preferable that alumina / silica as a cordierite forming raw material and alumina / silica as a molding aid are set separately. The average particle size of the cordierite forming raw material is preferably 2 to 40 μm in talc, 0.1 to 20 μm in kaolin, 0.1 to 30 μm in alumina, and 2 to 150 μm in silica. Alumina in the present application is a generic term for what will be present in the form of oxide as part of cordierite after firing, whether in the case of a cordierite forming raw material or a molding aid. In addition to the aluminum oxide, the concept includes aluminum hydroxide and the like. In addition, when mixing a cordierite forming raw material etc., the alumina and silica which are shaping | molding adjuvants may be added in the state mixed previously, and an alumina and a silica may be added separately, respectively. The latter is preferable in that the process can be simplified.

  The alumina particles and silica particles blended in the clay as the molding aid both have an average particle size of 1.0 μm or less, preferably 0.50 μm or less. Furthermore, at least one of the alumina particles and the silica particles preferably has an average particle diameter of 0.10 μm or less, and particularly preferably 0.01 to 0.10 μm. Furthermore, both the alumina particles and the silica particles preferably have an average particle diameter of 0.10 μm or less, and most preferably 0.01 to 0.10 μm. By reducing the average particle diameter of the alumina particles and the silica particles in this way, these particles can serve as a lubricant, increase the fluidity of the clay, and improve the moldability. If the average particle size of the alumina particles or silica particles is larger than 1.0 μm, the fluidity of the clay is not high, which is not preferable. Furthermore, the average particle diameter of the mixture of alumina particles and silica particles is preferably 1.0 μm or less, more preferably 0.01 μm or more and 0.80 μm or less, and 0.01 μm or more and 0.04 μm or less. Most preferably. For example, when the average particle diameter of the alumina particles is 1.0 μm and the average particle diameter of the silica particles is 0.02 μm, the mixing ratio of both is adjusted so that the average particle diameter in the mixed state is 0.04 μm or less. Therefore, very good fluidity can be obtained.

  The alumina particles and silica particles to be blended in the clay as the molding aid all have a total content of sodium, calcium and potassium as impurities (alkali metal / alkaline earth metal content) of 0.05% by mass. It is as follows. Furthermore, it is preferable that at least one of alumina particles and silica particles is 0.03% by mass or less. Furthermore, it is most preferable that both the alumina particles and the silica particles are 0.03% by mass or less. Heat of the honeycomb structure obtained by setting the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of the alumina particles and silica particles to 0.05 mass% or less An expansion coefficient can be made low and a thermal shock resistance can be improved. If the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of alumina particles or silica particles exceeds 0.05 mass%, the resulting honeycomb structure has a high thermal expansion coefficient. Therefore, it is not preferable. In addition, since natural alumina and silica are mostly those in which the total content of sodium, calcium and potassium as impurities (alkali metal / alkaline earth metal content) exceeds 0.05 mass%, sodium, It is preferable to artificially produce and use alumina and silica having a low calcium and potassium content. Specifically, it is preferable to use alumina produced by a vapor phase method. It is preferable to use silica prepared by a vapor phase method.

  The content of the molding aid in the clay is preferably 2 to 10% by mass and more preferably 2 to 5% by mass with respect to the total amount of the cordierite forming raw material and the molding auxiliary. When the content of the molding aid in the clay is in such a range, the moldability can be effectively improved. If the content of the molding aid in the clay is less than 2% by mass, it may be difficult to improve the moldability. If the content is more than 10% by mass, the amount of the produced clay is increased due to the bulk of the molding aid. This is because a large-scale mixing facility is required in light of the light and mixing work becomes difficult. Moreover, the influence which it has on the cordierite composition formed with the cordierite forming raw material can be suppressed small by setting the content of the molding aid to 10% by mass or less. In addition, even if the forming aids alumina and silica are added to the cordierite forming raw material, it is more preferable to be within the cordierite composition range. Further, when the content of the molding aid in the clay is more than 5% by mass with respect to the total amount of the cordierite forming raw material and the molding aid, a large amount of water as a dispersion medium may be required.

  The compounding ratio (mass ratio) of the alumina particles and silica particles in the clay is preferably alumina particles: silica particles = 10: 1 to 1:30, more preferably 1: 1 to 1:10. preferable. Combined use of alumina particles having an average particle size of 0.1 μm or less and silica particles having an average particle size of 0.1 μm or less in the above mixing ratio improves both formability, dimensional stability and strength (both And the influence on the cordierite composition can be suppressed.

  The silica particles are preferably amorphous silica. Since it is an amorphous silica, there is an advantage of low thermal expansion after firing.

  The alumina particles and silica particles that are molding aids are preferably block-shaped. Addition of water as a dispersion medium because the alumina particles and silica particles do not swell by absorbing water unlike the layered particles such as smectite (because they are non-swellable). The amount can be reduced, the drying speed of the honeycomb formed body is high, and the shrinkage rate during drying and firing of the honeycomb formed body is small. Therefore, good dimensional stability can be obtained. Here, the “block shape” means that the particle is not a layered particle formed by laminating a large number of thin plate-like alumina or the like, but a single lump. It is preferable that the length of the major axis is a lump that is twice or less the length of the minor axis. The length of the major axis is the length in the direction where the length of the particle is the longest, and the length of the minor axis is the length in the direction where the length of the particle is the shortest. The shape of the particles can be confirmed with an electron microscope image or the like.

  In the method for manufacturing a honeycomb structure of the present embodiment, it is preferable that water, a binder, a pore forming agent, a surfactant, and the like as a dispersion medium are further added to the clay.

  The blending amount of water as the dispersion medium is preferably set to an amount that allows the clay to have an appropriate hardness during extrusion molding of the honeycomb formed body. Specifically, it is preferably 30 to 50% by mass, and more preferably 30 to 40% by mass with respect to the entire clay. If the amount is less than 30% by mass, the clay may become hard and formability may be reduced. If the amount is more than 50% by mass, the drying efficiency of the honeycomb formed body may be reduced. On the other hand, if the amount of water is more than 40% by mass, the shrinkage ratio when the honeycomb formed body is dried may increase.

  In the method for manufacturing a honeycomb structure of the present embodiment, examples of the binder to be contained in the clay include methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. These may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the binder in the clay is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the cordierite forming raw material. When the amount of the binder is less than 1 part by mass, the moldability may be deteriorated, and when it is more than 10 parts by mass, a problem during firing may occur.

  In the method for manufacturing a honeycomb structure of the present embodiment, when manufacturing a honeycomb structure with a high porosity, it is preferable to include a pore forming agent in the clay. Such a pore-forming agent can form pores having a desired shape, size, and distribution in the honeycomb structure, increase the porosity, and obtain a honeycomb structure having a high porosity. Examples of such pore-forming agents include graphite, wheat flour, starch, phenol resin, water-absorbing resin (polymethyl methacrylate), polyethylene, polyethylene terephthalate, or foamed resin (acrylonitrile plastic balloon, etc.). it can. These form pores when they burn out. Although there is no restriction | limiting in particular about the content rate of a pore making material, It is preferable to set it as 20 mass% or less with respect to the whole clay. If the pore-forming agent content exceeds 20% by mass, problems during firing may occur.

  In the method for manufacturing a honeycomb structure of the present embodiment, the surfactant to be included in the clay may be any of anionic, cationic, nonionic, or amphoteric surfactants. Good. Examples of the anionic surfactant include fatty acid salts, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, polycarboxylates, and polyacrylates. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan (or sorbitol) fatty acid ester, and the like. The surfactant functions to improve the dispersibility of the raw material particles and to easily orient the raw material particles during extrusion molding. The amount of the surfactant in the clay is preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the cordierite forming raw material. When the surfactant is less than 0.1 parts by mass, the moldability may be deteriorated, and when it exceeds 5.0 parts by mass, the material characteristics may be deteriorated.

(Mixing, kneading)
In the method for manufacturing a honeycomb structure of the present embodiment, the method for mixing the cordierite forming raw material, the forming aid and the like is not particularly limited, and a known method can be used. For example, a method such as premixing can be used. And the method of kneading what mixed the above and forming a kneaded material is not specifically limited, A well-known method can be used. For example, kneading can be performed using a kneader, a vacuum kneader or the like.

(Molding)
Next, the obtained clay is formed into a honeycomb shape to produce a honeycomb formed body. The honeycomb formed body is preferably produced by extruding the obtained clay using a die having a desired cell shape, partition wall thickness, cell density and the like. The honeycomb formed body is preferably manufactured so that a honeycomb structure having the conditions described later can be obtained when the honeycomb structure is formed by firing.

(Dry)
Next, it is preferable to dry the obtained honeycomb formed body. The drying method is not particularly limited, and conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like can be used. Especially, the drying method which combined hot air drying, microwave drying, or dielectric drying is preferable at the point which can dry the whole molded object rapidly and uniformly.

(Calcination)
Next, it is preferable to calcine before firing the honeycomb formed body. “Preliminary firing” means an operation of burning and removing organic substances (binder, pore former, etc.) in the honeycomb formed body. Generally, the combustion temperature of the binder (organic binder) is about 100 to 300 ° C., and the combustion temperature of the pore former is about 200 to 800 ° C. Therefore, the calcining temperature may be about 200 to 1000 ° C. Although there is no restriction | limiting in particular as a calcination time, Usually, it is about 10 to 100 hours.

(Baking)
Next, the honeycomb formed body is fired to produce a honeycomb structure. By firing, the ceramic raw material of the honeycomb formed body can be sintered and densified to ensure a predetermined strength. As the firing conditions (temperature, time) of the cordierite forming raw material, it is preferable to fire at 1350 to 1440 ° C. for about 3 to 10 hours. The calcination and firing may be performed separately, but can also be performed continuously. The latter is preferable from the viewpoint of process reduction and energy efficiency.

  The shape of the honeycomb structure manufactured by the method for manufacturing a honeycomb structure of the present invention is not particularly limited, and examples thereof include a cylindrical shape, a quadrangular prism shape, a triangular prism shape, and other prismatic shapes.

  In addition, the cell shape of the honeycomb structure (cell shape in a cross section perpendicular to the central axis direction (cell extending direction) of the honeycomb structure) is not particularly limited, and examples thereof include a quadrilateral, a hexagon, and a triangle. Can be mentioned. The cell shape of the plurality of cells included in the honeycomb structure may be one type of cell shape, or may include a plurality of types of cell shapes. Examples of combinations of a plurality of types of cell shapes include arbitrary combinations such as a combination of an octagon and a quadrangle.

The porosity of the partition walls of the obtained honeycomb structure is preferably 10 to 80%, more preferably 25 to 65%, and particularly preferably 25 to 50%. When the porosity of the partition walls is less than 10%, the catalyst supporting ability may be deteriorated, and when the porosity of the partition walls exceeds 80%, the strength of the honeycomb structure may be decreased. The porosity is a value calculated from the total pore volume measured with a mercury intrusion porosimeter manufactured by Micromeritics, assuming that the true specific gravity of cordierite is 2.52 g / cm ³ . The porosity of the partition walls can be set to a desired value by adjusting the average particle diameter of the cordierite forming raw material, the average particle diameter of the pore forming agent, and the like at the time of manufacturing the honeycomb structure.

  The thickness of the partition walls of the obtained honeycomb structure is preferably 20 to 500 μm, more preferably 20 to 320 μm, and particularly preferably 20 to 210 μm. If the partition wall thickness is less than 20 μm, the strength of the honeycomb structure may be reduced. If the partition wall thickness is greater than 500 μm, the pressure loss increases and the heat capacity may increase. The thickness of the partition wall is a value measured by Nikon Corporation image measuring machine NEXIV.

  In the obtained honeycomb structure, the average pore diameter of the partition walls is preferably 2 to 80 μm, and more preferably 4 to 60 μm. By setting the average pore diameter of the partition walls in such a range, a suitable catalyst supporting property and pressure loss reducing effect can be obtained in a well-balanced manner. The average pore diameter is a value measured by the mercury intrusion porosimeter described above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
As a cordierite forming raw material, a mixture of 38% by mass of talc, 37% by mass of kaolin, 20% by mass of aluminum oxide, and 1% by mass of silica was used. As a forming aid, the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) is 0.03% by mass, alumina particles having an average particle size of 0.01 μm, and sodium, calcium and potassium. Amorphous silica particles having a total content (alkali metal / alkaline earth metal content) of 0.03% by mass and an average particle diameter of 0.01 μm were used. The average particle size of the whole molding aid was 0.01 μm, and the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) in the whole molding aid was 0.03% by mass. . The average particle diameter is a value measured with a transmission electron microscope. The measurement conditions of the transmission electron microscope were as follows: magnification: 20000 times and number of measured particles: 10 particles. Further, the “average value of the minor axis and the major axis” for one particle was defined as the “particle diameter” of the particle. A value obtained by averaging the “particle diameter” of each particle with respect to all the measured particles was defined as “average particle diameter”. Disperse by adding 4.0 parts by weight of a molding aid, 5.0 parts by weight of methylcellulose as a binder, and 0.5 parts by weight of potassium laurate soap as a surfactant, to 100 parts by weight of a cordierite forming raw material. Water was added as a medium so that it might become 37 mass% with respect to the whole clay, and it mixed and knead | mixed and prepared the clay. As the mixing and kneading apparatus, a sigma kneader was used.

  The obtained kneaded material was extruded using a ram type vacuum forming machine to produce a honeycomb formed body having a square cell cross-sectional shape and a cylindrical shape as a whole.

  Next, the obtained honeycomb formed body was dried by a hot air drying method (120 ° C., 1 hour).

  Next, the dried honeycomb formed body was fired to obtain a honeycomb structure. The firing conditions were 1350-1440 ° C. and 5 hours.

The obtained honeycomb structure has a cylindrical shape with a diameter of 70 mm and a central axis length of 100 mm, a partition wall thickness of 150 μm (6 mil), a cell density of 400 cells / square inch (62 cells / cm ² ), and an average partition wall The pore diameter was 5 μm and the partition wall porosity was 35%. The porosity and average pore diameter were measured by the mercury intrusion porosimeter described above. In Table 1, the column of cell structure indicates “partition wall thickness (mil) / cell density (cpsi)”, “1 (mil)” is 1/1000 inch, and “cpsi” is “cell / Square inch ”.

  With respect to the obtained honeycomb structure or in the manufacturing process of the honeycomb structure, “formability”, “shrinkage ratio”, “strength strength”, and “thermal expansion coefficient” were measured by the following methods. The results are shown in Table 2.

(Formability)
Formability is evaluated by the balance between the extrusion load (fluidity) and compressive stress (shape retention) of the clay, and is confirmed by the extrusion load value at the same compression stress. “◎” indicates that the extrusion load value is reduced by 50% or more from the time when the molding aid is not added, and “○” indicates that the extrusion load value decreases by “0% or more and less than 50%” from the time when the molding aid is not added. The case where it increases from the time when the agent is not added is defined as “Δ”, and “◎” is regarded as acceptable.

(Shrinkage factor)
The shrinkage rate (%) is the size of the honeycomb structure formed by drying and firing with respect to the size of the honeycomb formed body before drying ((honeycomb formed body before drying) − (honeycomb structure after firing)). ) Ratio (%). As for the size of each of the honeycomb formed body and the honeycomb structure, the diameter and the length in the central axis direction are measured. A shrinkage rate of 8.0% or less is accepted.

(Base strength)
The substrate strength (MPa) is measured by an autograph for the honeycomb structure. A substrate strength of 0.45 MPa or more is accepted. For the substrate strength, a four-point bending strength measurement was performed on a sample cut into 20 mm × 70 mm × 10 mm from the manufactured honeycomb structure. The load cell was 500 N, the load speed was 0.5 mm / min, and the span was 20-60 mm.

(Coefficient of thermal expansion)
The thermal expansion coefficient (/ ° C.) is measured with a differential thermal dilatometer for the honeycomb structure. A coefficient of thermal expansion of 0.30 × 10 ⁻⁶ / ° C. or less is accepted. The thermal expansion coefficient was measured using a thermomechanical analyzer (manufactured by Rigaku Corporation, THRMO PLUS2 / TMA) at a temperature rising rate of 10 ° C./min in the range of 40 to 800 ° C.

(Examples 2 to 4, 6 to 15, Reference Examples 1 to 3 )
The average particle diameter, impurity amount, blending amount, and blending ratio of alumina and silica as molding aids are the values shown in Table 1, and the blending amount of added water (water) and the cell structure are the values shown in Table 1. Except for the above, a honeycomb structure was manufactured in the same manner as in Example 1. In Example 12, fine crystalline silica was used as silica. In Table 1, the column “Amount of impurities (% by mass)” represents the total amount of impurities contained in alumina or the like, with potassium, calcium and sodium as impurities. In Table 1, “water (mass%)” indicates the ratio of water as a dispersion medium added to the clay to the entire clay. In the column of “cell structure” in Table 1, 8 (mil) / 300 (cpsi) is 200 (μm) /46.5 (cell / cm ² ), and 2 (mil) / 900 (cpsi). Is 50 (μm) /139.5 (cell / cm ² ). In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Examples 1 and 2)
A honeycomb structure was manufactured in the same manner as in Example 1 except that the average particle diameters of the alumina and silica as the forming aid and the added water were changed as shown in Table 1. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 3)
A honeycomb structure was manufactured in the same manner as in Example 2 except that the amounts of impurities of alumina and silica, which are forming aids, were changed as shown in Table 1. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 4)
As a molding aid, montmorillonite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 4.23 mass% and an average particle diameter of 1.6 μm were used, and the amount of water added was 43 mass. A honeycomb structure was manufactured in the same manner as in Example 1 except that the content was%. Montmorillonite particles are layered particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 5)
A honeycomb structure was manufactured in the same manner as in Comparative Example 4 except that the cell structure was 2 (mil) / 900 (cpsi). In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 6)
A honeycomb structure was manufactured in the same manner as in Comparative Example 4 except that the cell structure was 8 (mil) / 300 (cpsi). In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 7)
As the forming aid, bentonite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 4.68% by mass and an average particle size of 3.3 μm were used, and the added water was 43% by mass. A honeycomb structure was manufactured in the same manner as in Example 1 except that the content was%. Bentonite particles are layered particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 8)
As a forming aid, saponite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 3.20% by mass and an average particle size of 0.1 μm were used, and 43 wt. A honeycomb structure was manufactured in the same manner as in Example 1 except that the content was%. Saponite particles are layered particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 9)
As the molding aid, hectorite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 3.28% by mass and an average particle size of 0.1 μm were used, and the amount of water added was 45. A honeycomb structure was manufactured in the same manner as in Example 1 except that the mass% was used. Hectorite particles are layered particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 10)
As a forming aid, mica particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 5.34% by mass and an average particle size of 3.3 μm were used, and the added water was 43% by mass. A honeycomb structure was manufactured in the same manner as in Example 1 except that the content was%. Mica particles are layered particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 11)
Example, except that the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) is 3.06% by mass and the average particle size is 2.4 μm as the molding aid. In the same manner as in No. 1, a honeycomb structure was manufactured. Palygorskite particles are acicular particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 12)
As a molding aid, hydrotalcite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 0.07% by mass and an average particle size of 0.5 μm were used, and the added water was added. A honeycomb structure was manufactured in the same manner as in Example 1 except that the amount was 35% by mass. Hydrotalcite particles are plate-like particles whose major axis is twice or more the minor axis, and are not block-like particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 13)
Example, except that boehmite particles having a total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) of 0.05% by mass and an average particle size of 0.05 μm were used as molding aids In the same manner as in No. 1, a honeycomb structure was manufactured. Boehmite particles are block-like particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 14)
As molding aids, the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) is 0.05 mass%, boehmite particles having an average particle size of 0.05 μm, and sodium, calcium and potassium. Except that the total content (alkali metal / alkaline earth metal content) is 0.03% by mass, coarse crystalline silica particles having an average particle size of 5.0 μm, and the added water is 37% by mass, A honeycomb structure was manufactured in the same manner as in Example 1. Boehmite particles and coarse crystalline silica particles are block-like particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 15)
As molding aids, the total content of sodium, calcium and potassium (alkali metal / alkaline earth metal content) is 0.05 mass%, boehmite particles having an average particle size of 0.05 μm, and sodium, calcium and potassium. Except that the total content (alkali metal / alkaline earth metal content) is 0.03% by mass, coarse crystalline silica particles having an average particle size of 5.0 μm, and the added water is 37% by mass, A honeycomb structure was manufactured in the same manner as in Example 1. Boehmite particles and coarse crystalline silica particles are block-like particles. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

(Comparative Example 16)
A honeycomb structure was manufactured in the same manner as in Example 1 except that the molding aid was not blended and the added water was 35% by mass. In the same manner as in Example 1, the above characteristics were measured. The results are shown in Table 2.

  From Table 1, in the manufacturing method of the honeycomb structure of Examples 1-17, the moldability, the shrinkage rate, the substrate strength, and the thermal expansion coefficient were all good, and the amount of added water was small.

The method for manufacturing a honeycomb structure of the present invention collects dust and other particulate matter contained in incineration exhaust gas generated at the time of incineration of automobile exhaust gas or waste, and further NO in the exhaust gas. _{X 2} , CO, HC, and the like can be used for manufacturing a honeycomb structure used for adsorption and purification by a supported catalyst.

Claims (4)

In the cordierite forming raw material , the total content of sodium, calcium and potassium is 0.05% by mass or less, the average particle diameter is 0.10 μm or less, and the total content of sodium, calcium and potassium is 0.00. Silica particles having an average particle size of 0.10 μm or less are added as a molding aid to form a clay.
The content of the molding aid in the clay is 2 to 10% by mass with respect to the total amount of the cordierite forming raw material and the molding aid,
A method for manufacturing a honeycomb structure, wherein the obtained clay is formed into a honeycomb shape to produce a honeycomb formed body, and the honeycomb formed body is fired to obtain a honeycomb structure. The method for manufacturing a honeycomb structured body according to claim 1, wherein a mixing ratio of the alumina particles and the silica particles in the clay is alumina particles: silica particles = 10: 1 to 1:30. The method for manufacturing a honeycomb structured body according to claim 1 or 2 , wherein the silica particles are amorphous silica. The method for manufacturing a honeycomb structure according to any one of claims 1 to 3 , wherein 30 to 50 mass% of water is contained in the clay in the entire clay.