JP2004250324A - Method for producing ceramic honeycomb structure, and cordierite raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a ceramic honeycomb structure used for a ceramic filter having a low pressure drop property and strength durable under mechanical vibration, shock, or thermal shock in use and to provide a powdery cordierite raw material therefor. <P>SOLUTION: The ceramic honeycomb structure is produced from a raw material mainly comprising a cordierite raw material by extruding the raw material and firing the resultant molded product. The cordierite raw material contains 10-20 mass% silica source component except kaolin and talc. The silica source component contains more than 1 mass% but 10 mass% or less powder whose particle diameter is 75-250 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a ceramic honeycomb structure suitable for use in a ceramic honeycomb filter for removing fine particles contained in exhaust gas of a diesel engine, and a cordierite forming raw material therefor.

  Investigation of adopting a ceramic honeycomb filter for collecting fine particles with a structure in which the partition walls of the ceramic honeycomb structure are made porous and the exhaust gas containing the fine particles pass through the partition walls in order to remove the fine particles discharged from the diesel engine Is being promoted. FIG. 1 shows a front view and a side view of a ceramic honeycomb filter. Regarding the characteristics of the ceramic honeycomb filter, three are important: the collection efficiency of the fine particles, the pressure loss (pressure loss), and the collection time of the fine particles (the time from the start of collection to the time when a certain pressure loss is reached). Above all, the collection efficiency and the pressure loss are in a contradictory relationship. To increase the collection efficiency, the pressure loss increases and the collection time is shortened. The collection efficiency becomes poor. Techniques for controlling the porosity, average pore size, pore size distribution, and the size of pores present on the partition wall surface have been conventionally used for ceramic honeycomb structures so as to satisfy these conflicting filter characteristics. In addition, a method for producing a ceramic honeycomb structure for obtaining a desired porosity, average pore size, pore size distribution, and pore size present on the partition wall surface has been conventionally studied. .

  In the invention described in Patent Document 1, among the cordierite-forming raw materials, particles of 150 μm or more of the talc powder component and silica powder component constitute 3% by weight or less of the entire raw material, and particles of 45 μm or less of both components. Discloses a method for producing a porous ceramic honeycomb filter, wherein a cordierite-forming raw material is adjusted so as to be 25% by weight or less of the whole. According to the present production method, a porous material having a porosity of 45 to 65%, a small number of pores having a diameter of 100 μm or more, and mainly having pores having a diameter of 10 to 50 μm is advantageously obtained. The collection time can be extended without lowering the efficiency.

In the invention described in Patent Document 2, among the cordierite-forming raw materials, kaolin is contained in an amount of 0 to 10% by mass or less, and a silica (SiO ₂ ) source component other than kaolin and talc is powder having a particle size of 75 μm or more. To 1% by mass or less, and 15 to 45% by mass of aluminum hydroxide having a particle size of 1 to 10 μm and / or 0 to 20% of aluminum oxide having a particle size of 4 to 8 μm as an alumina (Al ₂ O ₃ ) source component. A method for producing a porous honeycomb filter, characterized in that the content is contained by mass%, is disclosed. According to this invention, the particle size of the silica (SiO ₂ ) source component other than kaolin and talc having a particle size of 75 μm or more is cut, and the particle size of the alumina (Al ₂ O ₃ ) source component can be adjusted to a desired value. As the range, the pore size distribution can be precisely controlled by the particle size distribution of the silica (SiO ₂ ) source component, so that the porosity is 65 to 75% and the pore size is narrow in the range of 10 to 50 μm. Can be formed at an extremely high rate, whereby the collection efficiency of fine particles is high, and an increase in pressure loss due to clogging of pores can be prevented.

  In the invention described in Patent Document 3, among the cordierite-forming raw materials, the average particle diameter of the talc and the silica raw material powder satisfies the relationship of (2 × average particle diameter of silica) ≧ (average particle diameter of talc). A production method in which the average particle diameter is 40 μm or less and the average particle diameter of silica is 80 μm or less is disclosed. According to the present invention, by using talc having a particle size smaller than twice the particle size of the silica used, the volume of pores having a porosity of 45 to 60% and a pore size of 100 μm or more is 10% or less of the total pore volume. A porous ceramic honeycomb filter is obtained in which the relationship between the specific surface area M of all pores opening and penetrating from the surface toward the inside and the surface roughness N on the filter surface is in the range of 1000M + 85N ≧ 530, and the collection time Is long, and the number of playbacks can be reduced.

Japanese Patent Publication No. 7-38930 JP-A-2002-219319 JP 2003-193820 A

  However, in the case of a filter having a structure in which a catalytic substance is carried on the surface of the partition wall of the ceramic honeycomb filter or pores in the partition wall and the fine particles deposited by the action of the catalytic substance are burned, the adoption of which has been considered in recent years. Since the pressure loss is increased due to clogging of pores by the catalyst substance, the pressure loss characteristic is lower than that of the conventional technology, and the strength is high enough to withstand mechanical vibration, shock or thermal shock during use. In addition, a ceramic honeycomb filter having a high collection efficiency of fine particles has been desired. As the characteristics of the partition walls of the ceramic honeycomb structure used for such a filter, the porosity is 60 to 80%, the average pore diameter is 15 to 25 μm, and the pore diameter is 20 in order to satisfy the conflicting characteristics as described above. The total pore volume of ４０40 μm or more needs to be 25% or more of the total pore volume, and the mere use of the method for manufacturing a ceramic honeycomb filter described in the above-mentioned patent document does not necessarily result in the above-described characteristics as described below. However, there is a problem that a ceramic honeycomb structure satisfying all the above conditions cannot be obtained.

  In the invention described in Patent Document 1, the porosity of the obtained honeycomb structure is about 45 to 60%, and in the case of a ceramic honeycomb filter in which a catalyst substance is supported on the surface of a partition wall or pores in the partition wall, the pressure is low. There was a problem that the loss was so great that it could not be used. Further, in the cordierite-forming raw material, particles of 150 μm or more of the talc powder component and silica powder component account for 3% by weight or less of the entire raw material, and particles of 45 μm or less of both components account for 25% or less of the whole. However, since the pores of the cordierite ceramics are mainly due to the skeleton in the firing process such as talc powder component and silica powder component, according to the operation of the present invention, Since the pore volume with a pore diameter of 100 μm or more and 10 μm or less is reduced and the pore volume with a pore diameter of 10 to 50 μm becomes relatively large (45% or more in the example), the average pore diameter is 25 μm or more. In some cases, the particle size becomes large, which may lead to a problem that the collection efficiency and strength of the fine particles are reduced. In addition, regarding the particle size of the cordierite-forming raw material, there is no description of the particle size distribution, except that the talc powder component and the silica powder component have a particle size of more than 150 μm, a particle size of less than 45 μm, and an average particle size. A honeycomb structure having a porosity of 60 to 80%, an average pore size of 15 to 25 µm, and a total pore volume of 20 to 40 µm or more with a total pore volume of 25% or more of the total pore volume cannot be obtained, and has a low pressure loss and high strength. There is a problem that a honeycomb filter satisfying the above condition cannot be manufactured.

In the invention described in Patent Document 2, among the cordierite-forming raw materials, a silica (SiO ₂ ) source component other than kaolin and talc is used, and a powder having a particle size of 75 μm or more is set to 1 mass% or less, and coarse particles having a particle size of 75 μm or more Although the powder is cut, silica (SiO ₂ ) source components other than kaolin and talc are said to be capable of forming pores having a pore diameter substantially corresponding to their particle diameters. ₂ ) Reducing the number of large pores formed from the source component leads to a relatively large number of small pores, resulting in an average pore diameter of less than 15 μm and an increase in the pressure loss of the ceramic honeycomb filter. Could lead to Regarding the particle size of the cordierite-forming raw material, a silica (SiO ₂ ) source component other than kaolin and talc is specified, and a powder having a particle size of 75 μm or more is specified as 1% by mass or less, but a particle size of less than 75 μm is specified. Except for the description of the average particle size in the examples, there is no description of the particle size distribution, and as described above, the silica (SiO ₂ ) source component other than kaolin and talc has a pore size substantially corresponding to this particle size. Due to the formation of pores, the total pore volume with a porosity of 60 to 80%, an average pore diameter of 15 to 25 μm, and a pore diameter of 20 to 40 μm or more may not always be obtained at 25% or more of the total pore volume. However, there is a problem that a honeycomb filter satisfying low pressure loss and high strength cannot be reliably manufactured.

In the invention described in Patent Document 3, the porosity of the obtained honeycomb structure is about 45 to 60%, and in the case of a ceramic honeycomb filter in which a catalyst substance is supported on the surface of the partition wall or the pores in the partition wall, the pressure is low. There was a problem that the loss was so great that it could not be used. Further, among the cordierite-forming raw materials, although the average particle diameter of talc and silica raw material powder that is considered to have a large contribution to pore formation is described, the particle size distribution is not described, and as described above. In addition, since the pore formation of cordierite ceramics is mainly based on the skeletons of the talc powder component and the silica powder component during the firing process, the porosity is 60 to 80%, and the average pore diameter is 15 to 25 μm. In addition, a total pore volume having a pore diameter of 20 to 40 μm or more cannot be obtained at 25% or more of the total pore volume, and there is a problem that a honeycomb filter satisfying low pressure loss and high strength cannot be reliably manufactured.
As described above, according to the conventional method for manufacturing a porous honeycomb filter, the total pore volume having a porosity of 60 to 80%, an average pore diameter of 15 to 25 μm, and a pore diameter of 20 to 40 μm or more is not necessarily a total pore volume. Thus, there was a problem that a ceramic honeycomb structure having 25% or more of the above was not obtained, and a honeycomb filter satisfying low pressure loss and high strength could not be manufactured.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, to provide a ceramic honeycomb structure used for a ceramic filter having low pressure loss characteristics and a strength capable of withstanding mechanical vibration, shock or thermal shock during use. An object of the present invention is to provide a production method for surely obtaining a body, and a cordierite-forming raw material powder therefor.

  In order to solve the above problems, the present inventors have conducted intensive studies and found that among the cordierite-forming raw materials, the content of the silica raw materials other than kaolin and talc was optimized and the particle size distribution of the silica raw materials was adjusted. Thereby, the distribution of the pores present in the partition walls of the ceramic honeycomb filter is optimized to a desired range, thereby having a low pressure loss characteristic and withstanding mechanical vibration, impact, or thermal shock during use. It has been found that a ceramic honeycomb filter having excellent strength can be obtained, and further, among the cordierite forming raw materials, by optimizing the content and the particle size distribution of the alumina source raw material in a preferable range, a lower pressure loss and a higher strength can be obtained. They have found that a ceramic honeycomb filter can be obtained, and have reached the present invention.

  That is, the method for manufacturing a ceramic honeycomb structure of the present invention is a method for plugging a predetermined flow channel end of a ceramic honeycomb structure made of a material having cordierite as a main crystal, and forming a porous porous partitioning the flow channel. A method for manufacturing a ceramic honeycomb structure used for a ceramic honeycomb filter for removing fine particles contained in exhaust gas by passing exhaust gas through partition walls, using a cordierite-forming raw material as a main raw material. A method for producing a ceramic honeycomb structure, wherein a predetermined molded body is extruded from, and then fired, wherein the cordierite-forming raw material contains 10 to 20% by mass of a silica source component other than kaolin and talc, and The silica source component is characterized by containing a powder having a particle size of 75 to 250 μm in an amount of more than 1% by mass and 10% by mass or less.

  In the method for manufacturing a ceramic honeycomb structure according to the present invention, the silica source components other than kaolin and talc may be 3 to 25% by mass of a powder having a particle size of 45 μm or more, 31 to 52% by mass of a powder having a particle size of 20 μm or more, and It is preferable to contain 49 to 70% by mass of powder having a diameter of 10 μm or more, 65 to 90% by mass of powder having a particle size of 5 μm or more, and 80 to 99.5% by mass of powder having a particle size of 2 μm or more.

  Further, in the method for manufacturing a ceramic honeycomb structure of the present invention, the cordierite-forming raw material contains at least 30% by mass or less of aluminum oxide as an alumina source component and 30% by mass or less of aluminum oxide as an alumina source component. And the aluminum oxide contains 5% by mass or less of a powder having a particle size of 45 μm or more, 2 to 22% by mass of a powder having a particle size of 20 μm or more, and 13 to 33% by mass of a powder having a particle size of 10 μm or more. It is preferable to contain 48 to 68% by mass of powder having a particle size of 5 μm or more and 85% by mass or more of powder having a particle size of 2 μm or more.

  In the method for manufacturing a ceramic honeycomb structure of the present invention, it is preferable that the foamed resin be contained in an amount of more than 4 parts by mass and 20 parts by mass or less based on 100 parts by mass of the ceramics material containing the cordierite-forming material as a main component.

  The cordierite-forming raw material used for producing the ceramic honeycomb structure of the present invention contains a silica source component other than kaolin and talc at 10 to 20% by mass, and the silica source component is a powder having a particle size of 75 to 250 μm. More than 1% by mass and 10% by mass or less, powder having a particle size of 45 μm or more is contained at 3 to 25% by mass, powder having a particle size of 20 μm or more is 31 to 52% by mass, and powder having a particle size of 10 μm or more is 49 to 70% by mass. %, Powder having a particle size of 5 μm or more is contained at 65 to 90% by mass, and powder having a particle size of 2 μm or more is contained at 80 to 99.5% by mass.

  Further, in the cordierite forming raw material used for producing the ceramic honeycomb structure of the present invention, at least 30% by mass or less of aluminum oxide and 0 to 30% by mass of aluminum oxide are contained as alumina source components, and the aluminum oxide is Containing 5% by mass or less of a powder having a particle size of 45 μm or more, 2 to 22% by mass of a powder having a particle size of 20 μm or more, 13 to 33% by mass of a powder having a particle size of 10 μm or more, and 48 powders having a particle size of 5 μm or more. It is preferable that the powder contains 85% by mass or more of powder having a particle size of 2 μm or more and 68% by mass or more.

Next, the function and effect of the present invention will be described.
In the method for manufacturing a ceramic honeycomb filter of the present invention, a predetermined flow channel end of a ceramic honeycomb structure made of a material containing cordierite as a main crystal is plugged, and air is exhausted to a porous partition partitioning the flow channel. A method for producing a ceramic honeycomb structure used for a ceramic honeycomb filter for removing fine particles contained in exhaust gas by passing a gas, wherein a cordierite-forming raw material is used as a main raw material, and a predetermined In the method for manufacturing a ceramic honeycomb filter that is fired after extruding a molded body, the cordierite-forming raw material contains 10 to 20% by mass of a silica source component other than kaolin and talc, and the silica source component includes: It contains a powder having a particle size of 75 to 250 μm in an amount exceeding 1% by mass and not more than 10% by mass. Therefore, for example, a ceramic honeycomb structure having a porosity of 60 to 80%, an average pore diameter of 15 to 25 μm, and a total pore volume of 20 to 40 μm or more having a total pore volume of 25% or more of the total pore volume can be obtained. A honeycomb filter satisfying low pressure loss, high collection rate, and high strength can be manufactured.

The pores formed in ceramics having cordierite as the main crystal are mainly due to the skeleton of silica source components such as quartz and fused silica during the firing process. It is known that it exists stably up to high temperatures, melts and diffuses at 1300 ° C. or higher, and forms pores. Therefore, when a silica source component other than kaolin and talc is contained in an appropriate amount within the range of 10 to 20% by mass, a desired amount of pores can be obtained. Here, the larger the content of the silica source component other than kaolin and talc, the larger the amount of pores formed. However, when the content exceeds 20% by mass, the main crystal of the ceramic honeycomb filter is corrugated. to maintain the light composition, i.e. ceramic honeycomb the chemical composition of the main component of the filter _SiO 2: 42 to 56 _{wt%, Al} 2 O 3: _30~45 wt%, MgO: to within 12-16% range It is necessary to reduce the addition amount of kaolin and talc, which are other silica source components, due to the cordierite crystal orientation formed along with the orientation of kaolin when the raw materials such as kaolin and talc pass through the die during extrusion molding. This is because the low thermal expansion is not sufficient, and the thermal expansion coefficient in the channel direction of the honeycomb structure increases, and the thermal shock resistance decreases. On the other hand, when the content is less than 10% by mass, the amount of the pores is reduced, so that it is difficult to achieve the porosity of 60% to 80%, and it is difficult to adjust the pore diameter, and the average pore diameter is 15 to 25 μm. This is because the total pore volume of 20 to 40 μm cannot achieve 25% or more of the total pore volume. Further, the reason that the silica source component other than kaolin and talc contains a powder having a particle size of 75 to 250 μm in a content of more than 1% by mass and 10% by mass or less is as described above in a ceramic having cordierite as a main crystal. The pores formed are mainly due to the form of silica source components such as quartz and fused silica in the firing process. As is known to melt and diffuse at temperatures of not less than 0 ° C. to form pores, a suitable amount of relatively large pores formed from silica source components other than kaolin and talc having a particle size of 75 to 250 μm are introduced. By doing so, the balance with the fine pores originally held by the cordierite ceramics, the average pore diameter of 15 to 25 μm, the total pore volume of 20 to 40 μm is the total pore volume In order to be more than 5% can be achieved is. When the silica source component other than kaolin and talc contains powder having a particle size of 75 to 250 μm in an amount of 1% by mass or less, the average pore diameter is less than 15 μm, and in some cases, the total pore volume of 20 to 40 μm is reduced to a total fine volume. This is because 25% or more of the pore volume cannot be obtained and the pressure loss of the ceramic honeycomb filter increases, and the silica source component other than kaolin and talc contains more than 10% by mass of a powder having a particle size of 75 to 250 μm. If the average pore diameter exceeds 25 μm, the collection efficiency and the strength of the ceramic honeycomb filter decrease. Further, when the silica source component other than kaolin and talc contains a powder having a particle size of more than 250 μm, the wall thickness of the ceramic honeycomb structure suitable for use in the ceramic honeycomb filter of the present invention is 0.1 mm. Since it is 25 mm to 0.45 mm, the material is clogged in the slit portion of the die during extrusion molding, and it becomes difficult to form the honeycomb structure. Therefore, in the present invention, the silica source components other than kaolin and talc are particles. It is preferable not to include a powder having a diameter exceeding 250 μm.

  From the above viewpoint, the content of the silica source component other than kaolin and talc in the cordierite-forming raw material is preferably from 15 to 19% by mass, and the silica source component other than kaolin and talc has a particle size of 75 to 250 μm. It is preferable to contain 1.5 to 4% by mass.

  In the method for manufacturing a ceramic honeycomb filter according to the present invention, the silica source component other than kaolin and talc is 3 to 25% by mass of a powder having a particle size of 45 μm or more, 31 to 52% by mass of a powder having a particle size of 20 μm or more, and a particle size of 31 to 52% by mass. It is preferable to contain 49 to 70% by mass of a powder having a particle size of 10 μm or more, 65 to 90% by mass of a powder having a particle size of 5 μm or more, and 80 to 99.5% by mass of a powder having a particle size of 2 μm or more. Here, the particle size distribution of the silica source components other than kaolin and talc is defined as described above because the pores formed in the ceramics having cordierite as the main crystal are subjected to the firing process as described above. , Mainly due to the form of silica source components such as quartz and fused silica, which are present more stably at higher temperatures than other raw materials, melt-diffuse at 1300 ° C. or higher, As is known to form pores, the pore size distribution of the cordierite-based ceramic honeycomb structure reflects the particle size distribution of silica source components other than kaolin and talc. Thereby, in the porous partition wall of the ceramic honeycomb filter obtained by this method, for example, the porosity is 60 to 80%, the average pore diameter is 18 to 23 μm, and the total pore volume of 20 to 40 μm is 25% or more of the total pore volume. Is achieved. Therefore, a ceramic honeycomb filter satisfying low pressure loss, high collection rate, and high strength can be manufactured.

  In view of the above, in the method for manufacturing a ceramic honeycomb filter of the present invention, the silica source component other than kaolin and talc is such that 10 to 16% by mass of a powder having a particle size of 45 μm or more and 38 to 44% by mass of a powder having a particle size of 20 μm or more. %, Powder having a particle size of 10 μm or more is contained at 56 to 62% by mass, powder having a particle size of 5 μm or more is contained at 72 to 78% by mass, and powder having a particle size of 2 μm or more is contained at 95 to 99% by mass. It is more preferable that a honeycomb structure having a total pore volume of 60 to 80%, an average pore diameter of 18 to 23 μm, and 20 to 40 μm of 25% or more of the total pore volume can be surely obtained.

  As a silica source component other than kaolin and talc, quartz, fused silica, mullite, and the like can be given.In particular, from the viewpoint that the pores are formed by melting and diffusing during the firing process and the pore diameter is easily controlled, quartz is used. And at least one kind of fused silica is preferable.

The silica source component may contain Na ₂ O, K ₂ O, and CaO as impurities. However, the content of these impurities is determined in the silica source component in order to prevent the coefficient of thermal expansion from increasing. , The total amount is preferably 0.1% by mass or less. The more preferable range of the content of Na ₂ O, K ₂ O and CaO of the silica source component is 0.01% by mass or less, and further preferably 0.006% by mass or less.

Cordierite forming raw material used in the present invention, as a main crystal is cordierite, i.e. the chemical composition of the main component _SiO 2: 42 to 56 _{wt%, Al} 2 O 3: _30~45 wt%, MgO: It is necessary to mix each raw material powder of the silica source component, the alumina source component, and the magnesia source component so as to be within the range of 12 to 16%. In addition to the above-mentioned kaolin and talc, for example, kaolin powder Talc powder, aluminum oxide powder, aluminum hydroxide powder and the like.

  Among these, as the alumina source component, those containing either one or both of aluminum oxide and aluminum hydroxide are preferable from the viewpoint of a small amount of impurities.

  The alumina source material preferably contains 6 to 42% by mass of aluminum hydroxide in the cordierite forming material, and preferably 30% by mass or less in the case of aluminum oxide. A more preferred range is 6 to 15% by mass for aluminum hydroxide and 12 to 25% by mass for aluminum oxide. An even more preferred range is 8 to 12% by mass for aluminum hydroxide and 20 to 24% by mass for aluminum oxide.

  In addition, the particle size of the alumina source material is such that, in terms of adjusting the pore size distribution obtained by the particle size distribution of the silica source component, the average particle size of The diameter is preferably 0.5 to 5 μm, and in the case of aluminum oxide, the average particle diameter is preferably 3 to 10 μm. Since aluminum oxide exists in the form of aluminum oxide up to a relatively high temperature during the firing process, its particle size distribution affects the pore distribution of the ceramic honeycomb filter of the present invention. 2% to 22% by mass of a powder having a particle size of 20 μm or more, 13 to 33% by mass of a powder having a particle size of 10 μm or more, 48 to 68% by mass of a powder having a particle size of 5 μm or more, and a powder having a particle size of 2 μm or more. When the content is 85% or more, the total pore volume of the porosity of 60 to 80%, the average pore diameter of 15 to 25 μm, and the pore diameter of 20 to 40 μm, which are preferable characteristics of the ceramic honeycomb filter, is 30% or more of the total pore volume. Is achieved, so that it is preferable.

  In addition, from the above viewpoint, aluminum oxide is 1% by mass or less of powder having a particle size of 45 μm or more, 9 to 15% by mass of powder having a particle size of 20 μm or more, 22 to 28% by mass of powder having a particle size of 10 μm or more, and More preferably, the powder contains 58 to 64% by mass of powder having a diameter of 5 μm or more and 94 to 99% by mass or more of powder having a particle size of 2 μm or more.

As the magnesia source component, for example, talc, magnesite, magnesium hydroxide and the like can be used, but it is preferable to contain talc in an amount of 40 to 43% by mass in terms of lowering the coefficient of thermal expansion, and the average particle size is , 5 to 20 μm are preferred. Further, the magnesia source component such as talc used in the present invention may contain Fe ₂ O ₃ , CaO, Na ₂ O, K ₂ O, etc. as impurities. Wherein the content of _Fe 2 _{O 3} is in a magnesia source component, preferably in order that a 0.5 to 2.5 mass% to obtain a particle size distribution of the ceramic honeycomb filter of the present invention, also _Na 2 O, The content of K ₂ O and CaO is preferably 0.35% by mass or less in total from the viewpoint of lowering the coefficient of thermal expansion.

  In the production method of the present invention, from the viewpoint that the pressure loss can be further reduced by further increasing the porosity, the cordierite-forming raw material contains, as an additive, a pore-forming agent for forming pores. Is preferred.

  Examples of the pore-forming agent include known wheat flour, graphite, starch powder, ceramic balloon, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic, phenol, epoxy, ethylene-vinyl acetate copolymer, styrene-butadiene block polymer, and styrene. -Isoprene block polymer, polymethyl methacrylate, methyl methacrylate acrylonitrile copolymer, urethane, wax, etc. can be used alone or in combination of one or more. Among them, methyl methacrylate / acrylonitrile copolymer Is preferred.

  Since the foamed resin formed of the methyl methacrylate / acrylonitrile copolymer contains gas (isobutane) inside, a ceramic honeycomb filter having a large porosity can be obtained with a small amount of added mass, Since the calorific value of the pore-forming agent in the firing step can be suppressed to a small value, the problem of cracking of the ceramic honeycomb structure due to combustion of the pore-forming agent, which is a problem during firing, can be reduced.

  However, when the amount of the pore-forming agent is increased, the porosity of the ceramic honeycomb filter can be increased, but the strength of the ceramic honeycomb filter is reduced, and the ceramic honeycomb filter is likely to be damaged by mechanical shock or thermal shock in actual use. All pore-forming agents have an upper limit of the amount added, and in the case of a foamed resin formed of a methyl methacrylate-acrylonitrile copolymer, more than 4 parts by mass and 20 parts by mass with respect to 100 parts by mass of a cordierite-forming raw material. The content is preferably as follows, more preferably 8 to 15 parts by mass.

In the present invention, other additives can be contained as needed. For example, a binder, a dispersant, a lubricant, and the like can be added.
Examples of the binder include methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol.Examples of the dispersant include ethylene glycol and fatty acid soap. Water-soluble wax, stearic acid and the like can be mentioned. The above additives can be used alone or in combination of two or more depending on the purpose.

Here, the ceramic honeycomb structure obtained by the method for manufacturing a ceramic honeycomb structure of the present invention has a thermal expansion coefficient of 1.25 × 10 ⁻⁶ / 40 ° C. to 800 ° C. in the flow direction of the porous partition wall. C. or lower is preferable because the thermal shock resistance at high temperatures is improved.

  Here, the ceramic honeycomb structure obtained by the method for manufacturing a ceramic honeycomb structure of the present invention has cordierite as a main crystal, but is oriented so that the C axis of the cordierite crystal is aligned within the partition wall plane. Is preferable because the thermal expansion coefficient is further reduced and the thermal shock resistance is excellent. Further, other crystal phases such as mullite, zircon, aluminum titanate, silicon carbide, zirconia, spinel, indialite, sapphirine, corundum, titania and the like may be contained.

  The cordierite-forming raw material used in the method for producing a ceramic honeycomb structure of the present invention contains a silica source component other than kaolin and talc at 10 to 20% by mass, and the silica source component has a particle size of 75 to 250 μm. More than 1% by mass and not more than 10% by mass, 3 to 25% by mass of powder having a particle size of 45 μm or more, 31 to 52% by mass of a powder having a particle size of 20 μm or more, and 49 to 70% of a powder having a particle size of 10 μm or more. It contains 65 to 90% by mass of powder having a particle size of 5 μm or more and 80 to 99.5% by mass of a powder having a particle size of 2 μm or more. Therefore, the porosity of the porous partition wall of the ceramic honeycomb structure obtained by this method is 60 to 80%, the average pore diameter is 15 to 25 μm, and the total pore volume of the pore diameter 20 to 40 μm is the total pore volume. It can be 25% or more. Thereby, a honeycomb filter satisfying low pressure loss, high collection rate, and high strength can be manufactured.

Further, in the cordierite-forming raw material of the present invention, aluminum oxide contains 30% by mass or less, and the aluminum oxide contains 5% by mass or less of powder having a particle size of 45 μm or more and 2 to 22% by mass of powder having a particle size of 20 μm or more. %, 13 to 33 wt% of the particle size 10μm or more powder, 48 to 68 wt% of the particle size 5μm or more powder, by containing a particle size 2μm or more powder than 85 wt%, the above-mentioned silica (SiO ₂ The pore size distribution obtained by the particle size distribution of the source component is adjusted, and the porosity of 60 to 80%, the average pore size of 15 to 25 μm, and the total pore volume of the pore size of 20 to 40 μm, which are preferable characteristics of the ceramic honeycomb filter, are obtained. Over 30% of the total pore volume is achieved.

  As described above, according to the method for manufacturing a ceramic honeycomb filter of the present invention and the cordierite-forming raw material therefor, since the combination, blending ratio, particle size distribution, etc. of the cordierite-forming raw material are adjusted to the optimal range. The distribution of pores formed in the partition walls of the ceramic honeycomb filter can be optimized to a desired range. For example, the porosity is 60 to 80%, the average pore diameter is 15 to 25 μm, and the total pore volume is 20 to 40 μm. More than 25% of the total pore volume is achieved. Thereby, a ceramic honeycomb filter having low pressure loss characteristics, particularly low pressure loss characteristics suitable for use in a continuous regeneration type purification device, and strength characteristics capable of withstanding mechanical vibration, impact, or thermal shock during use, and The manufacturing method can be provided.

The ceramic honeycomb filter of the present invention can be manufactured, for example, as follows.
For 100 parts by mass of the cordierite-forming raw material described above, 4 to 40 parts by mass of a pore former and 4 to 12 parts by mass of a binder are added and dry-mixed. It is a clay having plasticity. After extruding the formed body of the honeycomb structure from the kneaded clay by a known extrusion molding method, the formed body is dried by a known drying method, for example, a method such as microwave drying, dielectric drying, or hot air drying. Next, the dried formed body having the honeycomb structure is placed in a firing furnace and fired at a temperature of 1350 to 1440 ° C. to obtain a ceramic honeycomb structure.

Then, after arranging the end face masking film of the ceramic honeycomb structure, a perforated portion is formed alternately with respect to the flow path of the honeycomb structure, and the ceramic slurry for plugging separately prepared is added to the ceramic honeycomb structure. The ceramic slurry is introduced into the ceramic honeycomb structure through the perforated portion of the masking film. After the introduced slurry is solidified, the honeycomb structure is extracted from the ceramic slurry and dried to form a plugging material. Further, the ceramic slurry is introduced, solidified, and dried to form a plugging material on the other end side of the honeycomb structure by the same method, and then the masking film is peeled off. Thereafter, the plugging material is fired to integrate the partition walls and the plugging material, thereby obtaining a ceramic honeycomb filter in which predetermined flow paths on the inflow side and the outflow side of the exhaust gas are plugged.
The ceramic slurry may be introduced into the predetermined flow path with respect to the dried ceramic honeycomb structured body, and then the plugging material may be fired and integrated simultaneously with the formed body.

EXAMPLES Hereinafter, actual examples of the present invention will be described, but the present invention is not limited thereto.
(Examples 1 to 4)
Raw materials for forming cordierite such as talc, kaolin A, quartz A, aluminum oxide A, and aluminum hydroxide having an average particle size, a particle size distribution, and a CaO + Na ₂ O + K ₂ O content shown in Tables 1 to 3 are shown in the ratios shown in Table 4. Weighed. Next, as shown in Table 4, based on 100 parts by mass of the cordierite-forming raw material, 10 parts by mass of an acrylonitrile / methyl methacrylate copolymer containing isobutane as a foaming resin, 5% by mass of methylcellulose, and 2% by mass of hydroxypropylmethylcellulose. Was added and mixed. Here, the average particle size and particle size distribution of the raw material powders shown in Tables 1 to 4 were measured using a laser diffraction particle size distribution analyzer LMS-30 manufactured by Seishin Enterprise Co., Ltd. Thereafter, 25 parts by mass of water was added to 100 parts by mass of the cordierite-forming raw material, and mixing and kneading were performed to prepare a plasticizable clay, and the clay was charged into an extruder to form a honeycomb. A molded article having a structure was obtained. Next, after the obtained molded body was dried with a microwave dryer, hot air drying was performed, and both end faces were cut to predetermined dimensions. Next, a slurry composed of a cordierite-forming raw material was filled into the opening end of the flow path of the dried body of the honeycomb structure to a depth of about 10 mm from the end and dried, and both ends of the flow path having the structure shown in FIG. Were alternately plugged to obtain a dried ceramic honeycomb filter. Thereafter, firing was performed at 1420 ° C. for 10 hours to obtain ceramic honeycomb filters of Examples 1 to 4 having dimensional characteristics of Φ267 mm, length 304 mm, partition wall thickness 300 μm, partition wall pitch 1.58 mm.

The pressure loss characteristics of the obtained ceramic honeycomb filters were measured as follows. The ceramic honeycomb filter was placed on a pressure loss test stand, air was flowed at an air flow rate of 15 Nm ³ / min, and the differential pressure between the inflow side and the outflow side of the ceramic honeycomb filter at this time was measured to determine the pressure loss.

Thereafter, a test piece was cut out from the honeycomb filter after the test, and the porosity, the average pore diameter, the ratio of the total pore volume of 20 to 40 μm to the total pore volume, the thermal expansion coefficient, and the A-axis compression strength were measured. . The porosity, the average pore diameter, the measurement of the ratio of the total pore volume of 20 to 40 μm to the total pore volume is performed by a mercury intrusion method using Autopore III manufactured by Micromeritics, and a small piece cut out of the ceramic honeycomb filter is used. After being stored as a test piece in the measurement cell and depressurizing the inside of the cell, mercury was introduced and pressurized, and from the relationship between the pressure at this time and the volume of mercury pushed into the pores present in the sample, The relationship between the pore diameter and the cumulative pore volume is determined. At this time, the pressure for introducing mercury was 0.5 psi (0.35 × 10 ⁻³ kg / mm ² ), and the constants for calculating the pore diameter from the pressure were a contact angle = 130 ° and a surface tension of 484 dyne / cm 2. And At this time, the porosity was calculated from the measured value of the total pore volume, assuming that the true specific gravity of cordierite was 2.52 g / cm ³ . The measurement of the coefficient of thermal expansion was performed by installing a test piece having a size of 4.5 mm × 4.5 mm × 50 mm along the flow path of the honeycomb structure in a thermomechanical analyzer at 40 ° C. and 800 ° C. The coefficient of thermal expansion between ° C was determined. The measurement of the A-axis compressive strength was performed in accordance with the standard M505-87 "Test method for ceramic monolithic carrier for automobile exhaust gas purification catalyst" specified by the Japan Society of Automotive Engineers of Japan.

Table 5 shows the measurement results. The ceramic honeycomb filters of Examples 1 to 4 contained 11.8 to 17.5% by mass of quartz A as a silica source component other than kaolin and talc in the cordierite-forming raw material, and this quartz A had a particle size of 2.3% by mass of powder having a particle size of 75 to 250 μm, 14.2% by mass of particle size of 45 μm or more, 41.2% by mass of particle size of 20 μm or more, 59.4% by mass of particle size of 10 μm or more, and 59.4% by mass or more. 78.7% by mass, 88.7% by mass of a particle size of 2 μm or more, and 19.2 to 22.0% by mass of aluminum oxide A as an alumina source component. Particle size of 45 μm or more is 14.2% by mass, particle size of 20 μm or more is 12.5% by mass, particle size is 10 μm or more is 25.9% by mass, particle size is 5 μm or more is 62% by mass, and particle size is 2 μm or more is 97.8%. % By mass. Therefore, pores are formed in the partition walls, the porosity is 60.6 to 62.5%, the average pore diameter is 17.3 to 21.4 μm, and the total pore volume of 20 to 40 μm is the total pore volume. A ceramic honeycomb filter having a volume of 30.5% to 31.8% was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 185 to 189 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.7 to 4.0 MPa, and a practically no problem of 3 MPa or more. Values were obtained, and both low pressure loss and high strength could be achieved. In addition, a low coefficient of thermal expansion of 7 to 9 × 10 ⁻⁷ / ° C. was obtained.

(Comparative Examples 1 to 3)
The calcined kaolin was added to the same raw materials as in Examples 1 to 4, talc, kaolin, quartz A, aluminum oxide A, and aluminum hydroxide, weighed at the ratio shown in Table 4, and then weighed as shown in Table 4. To 100 parts by mass of the cordierite-forming raw material, 10 parts by mass of an acrylonitrile / methyl methacrylate copolymer containing isobutane as a foaming resin, 5% by mass of methylcellulose, and 2% by mass of hydroxypropylmethylcellulose were added and mixed. Thereafter, in the same manner as in Examples 1 to 4, kneading, molding, drying and baking were performed, and Comparative Examples 1 to 3 having dimensional characteristics of Φ267 mm, length 304 mm, partition wall thickness 300 μm, partition wall pitch 1.58 mm were performed. A ceramic honeycomb filter was obtained. Table 5 shows the results of measuring pressure loss, pore distribution, thermal expansion coefficient, and A-axis compressive strength of these in the same manner as in Example 1.

In the ceramic honeycomb filter of Comparative Example 1, the content of quartz A, which is a silica source component other than kaolin and talc, was 5.6% by mass in the cordierite-forming raw material, and the content of silica source components other than kaolin and talc was included. Since the proportion was less than 10% by mass, pores were not sufficiently formed by the quartz A, and the porosity of the partition walls was 57.2%, and 60% or more was not obtained. Therefore, the pressure loss of the ceramic honeycomb filter around top 200 mm 2 _O, increases the ceramic honeycomb filters of Examples 1 to 4, the ceramic honeycomb filter having both low pressure loss and high strength can not be obtained .

In the ceramic honeycomb filter of Comparative Example 2, the content of quartz A, which is a silica source component other than kaolin and talc, was 9% by mass in the cordierite-forming raw material, and the content of silica source components other than kaolin and talc was included. Since the proportion was less than 10% by mass, pores were not sufficiently formed by quartz A, and the porosity of the partition walls was 58.1%, which was not higher than 60%. Therefore, the pressure loss of the ceramic honeycomb filter around top 200 mm 2 _O, increases the ceramic honeycomb filters of Examples 1 to 4, the ceramic honeycomb filter having both low pressure loss and high strength can not be obtained .

  On the other hand, in the ceramic honeycomb filter of Comparative Example 3, the content of quartz A, which is a silica source component other than kaolin and talc, in the cordierite-forming raw material was 21% by mass, and the content of silica source components other than kaolin and talc was included. Since the ratio exceeded 20% by mass, the amount of coarse pores formed by quartz A increased, and the average pore diameter of the partition walls became 25.6 μm, which exceeded 25 μm. For this reason, the A-axis compressive strength of the ceramic honeycomb filter is 2.5 MPa, and 3 MPa or more, which is not a practical problem, cannot be obtained. Thus, the strength characteristics are lower than those of the ceramic honeycomb filters of Examples 1 to 4, and low pressure loss and high strength are obtained. A ceramic honeycomb filter satisfying both conditions was not obtained.

(Examples 5 to 8)
As shown in Table 4, the ceramic honeycomb filter of Example 5 was different from the ceramic honeycomb filter of Example 4 in that fused silica A was used as a silica source component other than kaolin and talc, and a cordierite-forming raw material was used as a pore-forming material. It was produced in the same manner as in Example 4 except that 12 parts by mass of an acrylonitrile-methyl methacrylate copolymer containing isobutane, which is a foamed resin, was added to 100 parts by mass.

As shown in Table 4, the ceramic honeycomb filter of Example 6 was the same as that of Example 5 except that kaolin A and kaolin B having different particle sizes were used as the kaolin with respect to the ceramic honeycomb filter of Example 5. Produced.
The ceramic honeycomb filters of Examples 7 and 8 were different from the ceramic honeycomb filter of Example 5 in that the mixing ratio of aluminum oxide A and aluminum hydroxide as the alumina source components was changed and the mixing ratio of kaolin, talc, and fused silica A was changed. It was produced in the same manner as in Example 5, except that the ratio was slightly changed.

Table 5 shows the results of Examples 5 to 8. The ceramic honeycomb filters of Examples 5 to 8 contained 17.5 to 18.2% by mass of fused silica as a silica source component other than kaolin and talc in the cordierite-forming raw material. 2.2 mass% of powder having a diameter of 75 to 250 μm, 13.6 mass% of particle diameter of 45 μm or more, 40.7 mass% of particle diameter of 20 μm or more, 58.6 mass% of particle diameter of 10 μm or more, and particle diameter of 5 μm or more 74.6% by mass, 97.4% by mass of a particle diameter of 2 μm or more, and 20 to 24.8% by mass of aluminum oxide A as an alumina source component. A diameter of 45 μm or more is 14.2 mass%, a particle diameter of 20 μm or more is 12.5 mass%, a particle diameter of 10 μm or more is 25.9 mass%, a particle diameter of 5 μm or more is 62 mass%, and a particle diameter of 2 μm or more is 97.8 mass%. % I have. Therefore, pores are formed in the partition walls, the porosity is 63.1 to 64.1%, the average pore diameter is 20.5 to 21.7 μm, and the total pore volume of 20 to 40 μm is the total pore volume. A ceramic honeycomb filter having a volume of 30.0% to 33.8% was obtained. The ceramic honeycomb filter, pressure loss characteristic 185~188mmH ₂ O, practically no problem 200 mm ₂ O or less is obtained, the A-axis compressive strength 3.5～3.6MPa, no practical problem 3MPa or more Value, and a ceramic honeycomb filter having both low pressure loss and high strength was obtained. In addition, a low coefficient of thermal expansion of 7 to 8 × 10 ⁻⁷ / ° C. was obtained.

(Examples 9 to 12)
The ceramic honeycomb filters of Example 9 and Example 12 were produced in the same manner as in Example 5 except that aluminum oxide B and aluminum oxide C were used as the alumina source components with respect to the ceramic honeycomb filter of Example 5. did.
The ceramic honeycomb filter of Example 10 is different from the ceramic honeycomb filter of Example 9 in that an acrylonitrile-methyl methacrylate copolymer containing isobutane, which is a foamed resin, is used in an amount of 100 parts by mass of a cordierite-forming raw material as a pore former. Except that it was added in parts by mass, it was produced in the same manner as in Example 10.
Further, the ceramic honeycomb filter of Example 11 is different from the ceramic honeycomb filter of Example 9 in that an acrylonitrile / methyl methacrylate copolymer containing isobutane, which is a foamed resin, based on 100 parts by weight of a cordierite forming raw material as a pore-forming material. Was prepared in the same manner as in Example 10 except that 10 parts by mass of, and 5 parts by mass of graphite were added.

Table 5 shows the results of Examples 9 to 12. The ceramic honeycomb filters of Examples 9 to 11 contained 17.5% by mass of fused silica A as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica A had a particle size of 75 to 75%. 2.2% by mass of a 250 μm powder, 13.6% by mass of a particle size of 45 μm or more, 40.7% by mass of a particle size of 20 μm or more, 58.6% by mass of a particle size of 10 μm or more, and 74.6% by mass of a particle size of 5 μm or more. It contains 97.4% by mass of 6% by mass and a particle size of 2 μm or more, and 22.8% by mass of aluminum oxide B as an alumina source component. 0.2% by mass, particle size of 20 μm or more, 11.2% by mass of particle size of 10 μm or more, 51.4% by mass of particle size of 5 μm or more, and 95.8% by mass of particle size of 2 μm or more. .
Therefore, pores are formed in the partition walls, the porosity is 61.7 to 67.0%, and the average pore diameter is 15.5. A ceramic honeycomb filter having a total pore volume of １６16.5 μm and 20 to 40 μm of 27.6 to 29.8% of the total pore volume was obtained. The ceramic honeycomb filter, pressure loss characteristic 196~198mmH ₂ O, practically no problem 200 mm ₂ O or less is obtained, the A-axis compressive strength 3.1～3.2MPa, no practical problem 3MPa or more Value, and a ceramic honeycomb filter having both low pressure loss and high strength was obtained. In addition, a low coefficient of thermal expansion of 7 to 9 × 10 ⁻⁷ / ° C. was obtained.

The ceramic honeycomb filter of Example 12 contained 17.5% by mass of fused silica A as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica A had a particle size of 75 to 250 μm. 2.2 mass% of powder, 13.6 mass% of particle diameter of 45 μm or more, 40.7 mass% of particle diameter of 20 μm or more, 58.6 mass% of particle diameter of 10 μm or more, and 74.6 mass of particle diameter of 5 μm or more. %, A particle size of 2 μm or more, 97.4% by mass, and an alumina source component of aluminum oxide C, 22.8% by mass, which contains 2% by mass of a particle size of 45 μm or more. It contains 24.1% by mass of a particle size of 20 μm or more, 43.1% by mass of a particle size of 10 μm or more, 71.1% by mass of a particle size of 5 μm or more, and 98.3% by mass of a particle size of 2 μm or more. Therefore, pores are formed in the partition walls, the porosity is 62.0%, the average pore diameter is 24.8 μm, and the total pore volume of 20 to 40 μm is 29.8% of the total pore volume. A ceramic honeycomb filter was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 196 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.1 MPa, and a practically problematic value of 3 MPa or more. A ceramic honeycomb filter having both pressure loss and high strength was obtained. Further, a low coefficient of thermal expansion of 8 × 10 ⁻⁷ / ° C. was obtained.

(Examples 13 to 18)
As shown in Table 4, the ceramic honeycomb filters of Examples 13 and 15 to 18 were different from the ceramic honeycomb filters of Example 3 in that the silica source components other than kaolin and talc were fused silica B, fused silica D, and fused silica E. , Fused silica F and fused silica H were used in the same manner as in Example 3. Further, as shown in Table 4, the ceramic honeycomb filter of Example 14 was the same as the ceramic honeycomb filter of Example 4 except that fused silica B was used as a silica source component other than kaolin and talc. In the same manner as in No. 4, it was produced.

Table 5 shows the results of Examples 13 to 18. The ceramic honeycomb filters of Examples 13 and 14 contained 16% by mass and 17.5% by mass of fused silica B as a silica source component other than kaolin and talc in the cordierite-forming raw material. 4.7 mass% of powder having a particle diameter of 75 to 200 μm, 26.6 mass% of particle diameter of 45 μm or more, 68.3 mass% of particle diameter of 20 μm or more, 93.4 mass% of particle diameter of 10 μm or more, and particle diameter of 5 μm It contains 94.2% by mass of the above and 99.8% by mass of a particle size of 2 μm or more, and contains 22.0 and 22.8% by mass of aluminum oxide A as an alumina source component. Therefore, pores are formed in the partition walls, the porosity is 62.1 to 62.7%, the average pore diameter is 24.1 to 24.6 µm, and the total pore volume of 20 to 40 µm is the total pore volume. A ceramic honeycomb filter having a volume of 32.3% to 33.8% of the volume was obtained. The ceramic honeycomb filter, pressure loss characteristic 186~188mmH ₂ O, practically no problem 200 mm ₂ O or less is obtained, the A-axis compressive strength 3.2～3.3MPa, no practical problem 3MPa or more Value, and a ceramic honeycomb filter having both low pressure loss and high strength was obtained. In addition, a low coefficient of thermal expansion of 7 to 8 × 10 ⁻⁷ / ° C. was obtained.

The ceramic honeycomb filter of Example 15 contained 16% by mass of fused silica D as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica D contained powder having a particle size of 75 to 200 μm. 1.8% by mass, 5.8% by mass with a particle size of 45 μm or more, 36.3% by mass with a particle size of 20 μm or more, 58.8% by mass with a particle size of 10 μm or more, 82.2% by mass with a particle size of 5 μm or more, It contains 97.5% by mass of a particle size of 2 μm or more, and contains 22.0% by mass of aluminum oxide A as an alumina source component. Therefore, pores are formed in the partition walls, the porosity is 61.0%, the average pore diameter is 20.6 μm, and the total pore volume of 20 to 40 μm is 41.9% of the total pore volume. A ceramic honeycomb filter was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 189 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.5 MPa, and a practically problematic value of 3 MPa or more. A ceramic honeycomb filter having both pressure loss and high strength was obtained. Further, a low coefficient of thermal expansion of 8 × 10 ⁻⁷ / ° C. was obtained.

The ceramic honeycomb filter of Example 16 contained 16% by mass of fused silica E as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica E contained powder having a particle size of 75 to 200 μm. 4.9% by mass, 21.5% by mass with a particle size of 45 μm or more, 43.1% by mass with a particle size of 20 μm or more, 55.7% by mass with a particle size of 10 μm or more, 68.5% by mass with a particle size of 5 μm or more, It contains 85.2% by mass of a particle diameter of 2 μm or more, and contains 22.0% by mass of aluminum oxide A as an alumina source component. Therefore, pores are formed in the partition walls, the porosity is 60.4%, the average pore diameter is 21.7 μm, and the total pore volume of 20 to 40 μm is 37.9% of the total pore volume. A ceramic honeycomb filter was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 187 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.6 MPa, and a value of 3 MPa or more which is practically no problem. A ceramic honeycomb filter having both pressure loss and high strength was obtained. Also, a low coefficient of thermal expansion of 7 × 10 ⁻⁷ / ° C. was obtained.

The ceramic honeycomb filter of Example 17 contained 16% by mass of fused silica F as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica F contained powder having a particle size of 75 to 200 μm. 5.3% by mass, 24.5% by mass with a particle size of 45 μm or more, 53.1% by mass with a particle size of 20 μm or more, 75.3% by mass with a particle size of 10 μm or more, 92.2% by mass with a particle size of 5 μm or more, It contains 99.8% by mass of a particle diameter of 2 μm or more, and contains 22.0% by mass of aluminum oxide A as an alumina source component. Therefore, pores are formed in the partition walls, the porosity is 60.5%, the average pore diameter is 23.5 μm, and the total pore volume of 20 to 40 μm is 35.6% of the total pore volume. A ceramic honeycomb filter was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 188 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.2 MPa, and a practically problematic value of 3 MPa or more. A ceramic honeycomb filter having both pressure loss and high strength was obtained. Further, a low coefficient of thermal expansion of 8 × 10 ⁻⁷ / ° C. was obtained.

The ceramic honeycomb filter of Example 18 contained 16% by mass of fused silica H as a silica source component other than kaolin and talc in the cordierite-forming raw material, and the fused silica H contained powder having a particle size of 75 to 200 μm. 1.3% by mass, 2.9% by mass with a particle size of 45μm or more, 29.0% by mass with a particle size of 20μm or more, 46.5% by mass with a particle size of 10μm or more, 62.5% by mass with a particle size of 5μm or more, It contains 78.5% by mass of a particle diameter of 2 μm or more, and contains 22.0% by mass of aluminum oxide A as an alumina source component. Therefore, pores are formed in the partition walls, the porosity is 62.3%, the average pore diameter is 15.6 μm, and the total pore volume of 20 to 40 μm is 30.5% of the total pore volume. A ceramic honeycomb filter was obtained. This ceramic honeycomb filter has a pressure loss characteristic of 193 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, an A-axis compressive strength of 3.8 MPa, and a practically problematic value of 3 MPa or more. A ceramic honeycomb filter having both pressure loss and high strength was obtained. Further, a low coefficient of thermal expansion of 8 × 10 ⁻⁷ / ° C. was obtained.

(Comparative Examples 4 to 9)
As shown in Table 4, the ceramic honeycomb filters of Comparative Examples 4 to 7 were different from the ceramic honeycomb filters of Example 3 in that silica source components other than kaolin and talc were quartz B, quartz C, fused silica C, and fused silica G. Was prepared in the same manner as in Example 3 except that The ceramic honeycomb filters of Comparative Examples 8 and 9 were different from the ceramic honeycomb filters of Comparative Examples 5 and 6 in the type and amount of the pore-forming agent to be added. In Comparative Example 7, graphite was used as a pore-forming agent, and in Comparative Example 8, foamed resin and polyethylene were used as pore-forming agents.

Table 5 shows the evaluation results. The ceramic honeycomb filters of Comparative Examples 4, 5, 7, and 8 contained 16% by mass of a silica source component other than kaolin and talc in the cordierite forming raw material, but the silica source component (quartz B or quartz C) was used. Alternatively, since the content of the powder having a particle diameter of 75 to 200 μm of quartz G) is 1% by mass or less, the size of the pores formed by the silica source component becomes small overall, and the average pore diameter of the partition walls is It was less than 15 μm. In particular, in the ceramic honeycomb filters of Comparative Examples 5 and 8, the ratio of the total pore volume of 20 to 40 µm to the total pore volume is less than 25%, and the porosity of the ceramic honeycomb filter of Comparative Example 8 is less than 60%. Met. For this reason, the ceramic honeycomb filters of Comparative Examples 4, 5, 7, and 8 had an A-axis compressive strength of 3.6 to 4.5 MPa, a value of 3 MPa or more, which was not problematic in practical use, but had a pressure loss characteristic. in 202~221mmH ₂ O, it becomes a value greater than 200 mm ₂ O as a practical problem, a ceramic honeycomb filter having both low pressure loss and high strength can not be obtained.

On the other hand, although the ceramic honeycomb filters of Comparative Examples 6 and 9 contained 16% by mass of a silica source component (fused silica C) other than kaolin and talc in the cordierite-forming raw material, particles of the silica source component were not used. Since the content of the powder having a diameter of 75 to 200 μm is 24.3% by mass, the size of the pores formed by the silica source component becomes large as a whole, and the average pore diameter of the partition walls exceeds 25 μm. I was Therefore, the ceramic honeycomb filter of Comparative Example 6 and 9, a pressure loss characteristic 175～192MmH ₂ O, practically no problem though 200mmH were ₂ O or less, A-axis compressive strength 1.0~1.5MPa Thus, a practically problematic 3 MPa or more was not obtained, and a ceramic honeycomb filter having both low pressure loss and high strength was not obtained.

(Examples 19 to 21)
As shown in Table 4, the ceramic honeycomb filters of Examples 19 to 21 were the same as the examples except that the type and amount of the pore forming agent to be added were changed with respect to the ceramic honeycomb filters of Example 3. Produced. In Example 19, graphite and polymethyl methacrylate (PMMA) were used as the pore former, in Example 20, foamed resin and graphite, and in Example 21, wheat flour was used.

As shown in the evaluation results in Table 5, the ceramic honeycomb filters of Examples 19 to 21 contained 16% by mass of quartz A as a silica source component other than kaolin and talc among the cordierite forming raw materials. 2.3% by mass of powder having a particle size of 75 to 250 μm in quartz A, 14.2% by mass of particle size of 45 μm or more, 41.2% by mass of particle size of 20 μm or more, 59.4% by mass of particle size of 10 μm or more, It contains 75.3% by mass of a particle size of 5 μm or more, 88.7% by mass of a particle size of 2 μm or more, and contains 22% by mass of aluminum oxide A as an alumina source component. For this reason, a ceramic honeycomb filter formed in the partition wall and having a porosity of 60 to 80%, an average pore diameter of 15 to 25 μm, and a total pore volume of 20 to 40 μm of 25% or more of the total pore volume is provided. Obtained. This ceramic honeycomb filter has a pressure loss characteristic of 186 to 189 mmH ₂ O, a practically no problem of 200 mmH ₂ O or less, and an A-axis compressive strength of 3.5 to 3.7 MPa, a practically problematic of 3 MPa or more. Value, and a ceramic honeycomb filter having both low pressure loss and high strength was obtained. In addition, a low coefficient of thermal expansion of 8 to 9 × 10 ⁻⁷ / ° C. was obtained.

(Examples 22 to 25)
Catalyst materials made of platinum (Pt), cerium oxide, and activated alumina were supported on the surface and inside of the partition wall by a wash coat method on the ceramic honeycomb filters manufactured in the same manner as in Examples 1 to 4. Was obtained. At this time, the carried amount was 2 g / L in Pt amount (meaning that 2 g of Pt was carried per 1 L of honeycomb filter volume). Table 6 shows the results of measuring the pressure loss and the A-axis compressive strength of these in the same manner as in Example 1.
In the partition walls of the ceramic honeycomb filters of Examples 1 to 4, pores obtained by a silica source component other than kaolin and talc are formed, the porosity is 60 to 80%, the average pore diameter is 15 to 25 µm, and Since the total pore volume of ４０40 μm is 25% or more of the total pore volume, the pressure loss characteristics of the ceramic honeycomb filters of Examples 22 to 25 in which the catalyst substance is supported are the same as those before the catalyst is supported. most unchanged, 200 mm ₂ O or lower pressure loss is obtained. On the other hand, the A-axis compressive strength was 3 MPa or more, which was practically no problem, and a ceramic honeycomb filter having both low pressure loss and high strength was obtained.

(1) and (2) are a front view and a side view, respectively, showing an example of a ceramic honeycomb filter.

Explanation of reference numerals

1: partition,
2: flow path,
3: ceramic honeycomb filter,
4: plugging material,

Claims (6)

A method for producing a ceramic honeycomb structure, wherein a cordierite-forming raw material is used as a main raw material, a predetermined molded body is extruded from the raw material, and then fired, wherein the cordierite-forming raw material is silica other than kaolin and talc. A ceramic honeycomb structure comprising: a source component in an amount of 10 to 20% by mass; and the silica source component contains a powder having a particle size of 75 to 250 µm in an amount of more than 1% by mass and 10% by mass or less. Manufacturing method. The silica source components other than kaolin and talc are as follows: 3 to 25% by mass of a powder having a particle size of 45 μm or more, 31 to 52% by mass of a powder having a particle size of 20 μm or more, and 49 to 70% by mass of a powder having a particle size of 10 μm or more. 2. The method for producing a ceramic honeycomb structure according to claim 1, wherein the powder contains 65 to 90% by mass of powder having a particle size of 5 μm or more and 80 to 99.5% by mass of powder having a particle size of 2 μm or more. . The cordierite-forming raw material contains at least 30% by mass or less of aluminum oxide as an alumina source component, and the aluminum oxide contains 5% by mass or less of a powder having a particle size of 45 μm or more and 2 to 22% of a powder having a particle size of 20 μm or more. It is characterized by containing 13 to 33% by mass of a powder having a particle size of 10 μm or more, 48 to 68% by mass of a powder having a particle size of 5 μm or more, and 85% by mass or more of a powder having a particle size of 2 μm or more. The method for manufacturing a ceramic honeycomb structure according to claim 1 or 2, wherein The ceramic according to any one of claims 1 to 3, wherein the foamed resin is contained in an amount of more than 4 parts by mass and 20 parts by mass or less with respect to 100 parts by mass of the ceramic raw material containing the cordierite-forming raw material as a main component. A method for manufacturing a honeycomb structure. A cordierite-forming raw material used for manufacturing a ceramic honeycomb structure, comprising 10 to 20% by mass of a silica source component other than kaolin and talc, and wherein the silica source component is a powder having a particle size of 75 to 250 μm. More than 10% by mass and less than 10% by mass, 3 to 25% by mass of a powder having a particle size of 45 μm or more, 31 to 52% by mass of a powder having a particle size of 20 μm or more, and 49 to 70% by mass of a powder having a particle size of 10 μm or more. A cordierite-forming raw material containing 65 to 90% by mass of powder having a particle size of 5 µm or more and 80 to 99.5% by mass of powder having a particle size of 2 µm or more. A cordierite-forming raw material used for manufacturing a ceramic honeycomb structure, wherein the cordierite-forming raw material contains at least 30% by mass or less of aluminum oxide as an alumina source component, and the aluminum oxide has a particle size of 45 μm or more. 5% by mass or less, powder having a particle size of 20 μm or more is contained at 2 to 22% by mass, powder having a particle size of 10 μm or more is 13 to 33% by mass, powder having a particle size of 5 μm or more is 48 to 68% by mass, and particle size is 2 μm. The cordierite-forming raw material according to claim 7, comprising 85% by mass or more of the above powder.

Images