WO2010150609A1 - Honeycomb filter - Google Patents

Honeycomb filter Download PDF

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Publication number
WO2010150609A1
WO2010150609A1 PCT/JP2010/058715 JP2010058715W WO2010150609A1 WO 2010150609 A1 WO2010150609 A1 WO 2010150609A1 JP 2010058715 W JP2010058715 W JP 2010058715W WO 2010150609 A1 WO2010150609 A1 WO 2010150609A1
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WIPO (PCT)
Prior art keywords
aluminum titanate
number average
axis diameter
columnar
honeycomb filter
Prior art date
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PCT/JP2010/058715
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French (fr)
Japanese (ja)
Inventor
隆寛 三島
伸樹 糸井
宏仁 森
Original Assignee
大塚化学株式会社
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Publication of WO2010150609A1 publication Critical patent/WO2010150609A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2425—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material
    • B01D46/24494—Thermal expansion coefficient, heat capacity or thermal conductivity
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
    • C04B35/478—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on aluminium titanates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2425—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material
    • B01D46/2429—Honeycomb filters characterized by parameters related to the physical properties of the honeycomb structure material of the honeycomb walls or cells
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2451—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure
    • B01D46/2476—Monolithic structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2451—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure
    • B01D46/2482—Thickness, height, width, length or diameter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
    • B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
    • B01D46/2418—Honeycomb filters
    • B01D46/2451—Honeycomb filters characterized by the geometrical structure, shape, pattern or configuration or parameters related to the geometry of the structure
    • B01D46/2484—Cell density, area or aspect ratio
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0006—Honeycomb structures
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3232—Titanium oxides or titanates, e.g. rutile or anatase
    • C04B2235/3234—Titanates, not containing zirconia
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5296—Constituents or additives characterised by their shapes with a defined aspect ratio, e.g. indicating sphericity
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
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    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5463—Particle size distributions
    • C04B2235/5472—Bimodal, multi-modal or multi-fraction
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
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    • C04B2235/77—Density
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient

Definitions

  • the present invention relates to a honeycomb filter made of aluminum titanate.
  • Aluminum titanate is expected to be a porous material used in automobile exhaust gas treatment catalyst carriers, diesel particulate filters (DPFs), etc. because of its low thermal expansion, excellent thermal shock resistance, and high melting point. Development is underway.
  • Patent Document 1 an aluminum titanate sintered body having high strength and less mechanical strength deterioration with respect to repeated thermal history is obtained without impairing the high melting point and low thermal expansion property of aluminum titanate. Therefore, it has been proposed to sinter aluminum titanate added with magnesium oxide and silicon oxide.
  • Patent Document 2 discloses that an exhaust gas filter is manufactured using columnar aluminum titanate, and when the longitudinal direction of the columnar particles has a negative thermal expansion coefficient, the direction perpendicular to the longitudinal direction is positive thermal expansion. It has been proposed to manufacture an exhaust gas filter that has a coefficient or a negative thermal expansion coefficient in the direction perpendicular to the longitudinal direction when the longitudinal direction of the columnar particles has a positive thermal expansion coefficient.
  • honeycomb filter made of aluminum titanate As described above, it has a low thermal expansion coefficient, is high in strength, and requires little deterioration in mechanical strength with respect to repeated thermal history. The rate is sought.
  • An object of the present invention is to provide a honeycomb filter having a low thermal expansion coefficient, a high porosity, high strength and excellent thermal shock resistance.
  • the number average major axis diameter of granular aluminum titanate is smaller than the number average minor axis diameter of columnar aluminum titanate.
  • columnar aluminum titanate and granular aluminum titanate are mixed and used in the above ratio, and the number average major axis diameter of granular aluminum titanate is the number average short axis of columnar aluminum titanate. It is characterized by being smaller than the shaft diameter.
  • the columnar aluminum titanate When the columnar aluminum titanate is formed by extrusion, the columnar aluminum titanate is arranged so that the longitudinal direction of the columnar shape is aligned in parallel with the extrusion direction. For this reason, the C-axis having a low thermal expansion coefficient is oriented, and the thermal expansion coefficient of the honeycomb filter in the extrusion direction can be lowered.
  • columnar aluminum titanate has a large aspect ratio
  • columnar aluminum titanate particles tend to overlap each other, and the strength can be increased.
  • the aspect ratio is large, the porosity can be increased.
  • the honeycomb filter using columnar aluminum titanate has a large coefficient of thermal expansion in the direction perpendicular to the extrusion direction, there is a large difference in coefficient of thermal expansion between the extrusion direction and the direction perpendicular to the extrusion direction. Produce. As a result, the honeycomb filter has high strength but is inferior in thermal shock resistance.
  • columnar aluminum titanate and granular aluminum titanate are mixed and used so as to have a ratio within the above predetermined range.
  • granular aluminum titanate particles can be arranged between columnar aluminum titanate particles, and the coefficient of thermal expansion in the direction perpendicular to the extrusion direction can be obtained. Can be lowered. For this reason, the difference between the thermal expansion coefficient in the extrusion direction and the thermal expansion coefficient in the direction perpendicular thereto can be reduced, and the thermal shock resistance can be improved.
  • the structure of aluminum titanate in the honeycomb filter can be densified, and a honeycomb filter having high porosity and high strength can be obtained.
  • granular aluminum titanate having a number average major axis diameter smaller than that of columnar aluminum titanate is used.
  • a honeycomb filter having high porosity and strength and excellent thermal shock resistance can be obtained.
  • the number average major axis diameter of the granular aluminum titanate is larger than the number average minor axis diameter of the columnar aluminum titanate, the overlap between the columnar aluminum titanates decreases, the strength decreases, and the sintering becomes difficult to proceed. The thermal expansion coefficient in the direction perpendicular to the extrusion direction cannot be sufficiently reduced, and the thermal shock resistance is lowered.
  • the columnar aluminum titanate in the present invention can be produced by mixing raw materials containing a titanium source, an aluminum source, and a magnesium source while pulverizing them into mechanochemicals and firing the pulverized mixture.
  • a raw material in which a magnesium source is mixed so as to be within a range of 0.5 to 2.0% by weight in terms of respective oxides with respect to the total of the titanium source and the aluminum source.
  • the temperature for firing the pulverized mixture is preferably a temperature in the range of 1300 to 1600 ° C. By firing within such a temperature range, the columnar aluminum titanate of the present invention can be produced more efficiently.
  • Calcination time is not particularly limited, but it is preferably performed within a range of 0.5 hours to 20 hours.
  • Mechanochemical crushing includes a method of crushing while giving a physical impact. Specifically, pulverization by a vibration mill can be mentioned. By pulverizing with a vibration mill, the disruption of atomic arrangement and the decrease in interatomic distance occur simultaneously due to the shear stress caused by the grinding of the mixed powder, resulting in atomic movement of the contact part of different particles, resulting in a metastable phase. Can be obtained. Thereby, a pulverized mixture with high reaction activity is obtained, and the columnar aluminum titanate of the present invention can be produced by firing the pulverized mixture with high reaction activity.
  • the mechanochemical pulverization in the present invention is generally performed as a dry process without using water or a solvent.
  • the mixing treatment time by mechanochemical pulverization is not particularly limited, but generally it is preferably within the range of 0.1 to 6 hours.
  • the raw materials used in the present invention include a titanium source, an aluminum source, and a magnesium source.
  • a titanium source a compound containing titanium oxide can be used. Specific examples include titanium oxide, rutile ore, titanium hydroxide wet cake, and hydrous titania.
  • the aluminum source a compound that generates aluminum oxide by heating can be used.
  • Specific examples include aluminum oxide, aluminum hydroxide, and aluminum sulfate. Among these, aluminum oxide is particularly preferably used.
  • magnesium source a compound that generates magnesium oxide by heating can be used, and specific examples include magnesium hydroxide, magnesium oxide, and magnesium carbonate. Among these, magnesium hydroxide and magnesium oxide are particularly preferably used.
  • the raw material may further contain a silicon source.
  • Examples of the silicon source include silicon oxide and silicon. Among these, silicon oxide is particularly preferably used.
  • the content of the silicon source in the raw material is preferably in the range of 0.5 to 10% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. By setting it within such a range, columnar aluminum titanate can be more stably produced.
  • the granular aluminum titanate of the present invention can be produced by, for example, a conventionally known production method. Moreover, it can manufacture also by mixing the raw material containing a titanium source, an aluminum source, and a magnesium source, grind
  • the mixing ratio of the magnesium source is preferably mixed so as to be more than 2.0% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source.
  • granular aluminum titanate can also be produced by mixing raw materials into mechanochemicals without grinding.
  • the mixing ratio of the aluminum source and the silica source when producing the granular aluminum titanate can be the same ratio as when producing the columnar aluminum titanate.
  • the aspect ratio of aluminum titanate in the present invention is a value determined from the ratio of number average major axis diameter / number average minor axis diameter as described above.
  • the number average major axis diameter and the number average minor axis diameter can be measured by, for example, a flow particle image analyzer.
  • the number average major axis diameter of the columnar aluminum titanate in the present invention is preferably in the range of 7 to 17 ⁇ m, and the number average minor axis diameter is preferably in the range of 5 to 10 ⁇ m.
  • the number average major axis diameter of the granular aluminum titanate is preferably in the range of 0.1 to 10 ⁇ m, and the number average minor axis diameter is preferably in the range of 0.1 to 10 ⁇ m.
  • granular aluminum titanate and columnar aluminum titanate are selected so that the number average major axis diameter of granular aluminum titanate is smaller than the number average minor axis diameter of columnar aluminum titanate.
  • the aspect ratio of the columnar aluminum titanate in the present invention is preferably in the range of 1.3 to 5.0, more preferably in the range of 1.3 to 2.5, and still more preferably in the range of 1.3 to Within the range of 2.0.
  • the aspect ratio of the granular aluminum titanate in the present invention is preferably 1.2 or less, and more preferably in the range of 1.1 to 1.0.
  • honeycomb filter of the present invention columnar aluminum titanate and granular aluminum titanate are mixed and used as described above, so that the thermal expansion coefficient between 30 and 800 ° C. in the direction perpendicular to the extrusion direction can be obtained.
  • the difference between the thermal expansion coefficient in the extrusion direction and the thermal expansion coefficient in the direction perpendicular thereto can be reduced, and a honeycomb filter having excellent thermal shock resistance can be obtained.
  • the honeycomb filter of the present invention is a honeycomb filter obtained by firing a molded body formed by extrusion, and has a thermal expansion coefficient of 2 to 30 ° C. in a direction perpendicular to the extrusion direction. It is characterized by being 0 ⁇ 10 ⁇ 6 / ° C. or less.
  • the coefficient of thermal expansion in the direction perpendicular to the extrusion direction is more preferably in the range of 0.0 to 1.5 ⁇ 10 ⁇ 6 / ° C.
  • the thermal expansion coefficient between 30 and 800 ° C. in the extrusion direction of the honeycomb filter of the present invention is preferably 0.0 ⁇ 10 ⁇ 6 / ° C. or less, more preferably ⁇ 2.0 to 0.0.
  • the range is ⁇ 10 -6 / ° C.
  • the honeycomb filter of the present invention is a mixture of columnar aluminum titanate and granular aluminum titanate prepared by adding, for example, a pore-forming agent, a binder, a dispersant, and water. Can be manufactured by firing the molded body obtained by drying after plugging on one side so that the cell opening has a checkered pattern. . Examples of the firing temperature include 1400 to 1600 ° C.
  • Examples of pore-forming agents include graphite, graphite, wood powder, and polyethylene.
  • Examples of the binder include methyl cellulose, ethyl cellulose, and polyvinyl alcohol.
  • Examples of the dispersant include fatty acid soap and ethylene glycol. The amount of pore-forming agent, binder, dispersant, and water can be adjusted as appropriate.
  • a honeycomb filter having a low thermal expansion coefficient, high porosity, high strength, and excellent thermal shock resistance can be obtained.
  • FIG. 1 is a scanning electron micrograph showing columnar aluminum titanate used in an example according to the present invention.
  • FIG. 2 is a scanning electron micrograph showing granular aluminum titanate used in the examples according to the present invention.
  • FIG. 3 is a perspective view showing the honeycomb sintered body.
  • FIG. 4 is a perspective view showing a measurement sample cut out from the honeycomb sintered body.
  • FIG. 5 is a schematic diagram for explaining a method for measuring the bending strength of a honeycomb sintered body.
  • FIG. 6 is a perspective view showing a measurement sample cut out from the honeycomb sintered body.
  • FIG. 7 is a perspective view showing a honeycomb sintered body.
  • FIG. 1 is a scanning electron micrograph showing columnar aluminum titanate used in an example according to the present invention.
  • FIG. 2 is a scanning electron micrograph showing granular aluminum titanate used in the examples according to the present invention.
  • FIG. 3 is a perspective view showing the honeycomb sintered body.
  • FIG. 4 is
  • FIG. 8 is a perspective view showing a measurement sample for measuring the X-ray diffraction of the extruded surface cut out from the honeycomb sintered body.
  • FIG. 9 is a diagram showing an X-ray diffraction chart of columnar aluminum titanate obtained in an example according to the present invention.
  • FIG. 1 is an SEM photograph showing the columnar aluminum titanate obtained in this production example.
  • FIG. 9 is a view showing an X-ray diffraction chart of the columnar aluminum titanate obtained in this production example.
  • FIG. 2 is an SEM photograph showing the granular aluminum titanate obtained in this production example.
  • the obtained product was Al 2 TiO 5 .
  • the obtained product was Al 2 TiO 5 .
  • Table 1 shows the composition, shape, major axis diameter (number average major axis diameter), minor axis diameter (number average minor axis diameter), and aspect ratio of the aluminum titanates obtained in Production Examples 1 to 5.
  • the aluminum titanate obtained in Production Examples 1 and 2 is a columnar aluminum titanate having an aspect ratio of 1.3 or more. Further, the aluminum titanate obtained in Production Examples 3 to 5 is granular aluminum titanate having an aspect ratio of less than 1.3.
  • honeycomb sintered bodies were manufactured by using a mixture of aluminum titanate as a base material and aluminum titanate as an additive.
  • the columnar aluminum titanate of Production Example 1 or 2 was used as a base material, and the granular aluminum titanate of Production Example 4 or 5 was used as an additive.
  • the mixing ratio of the base material and the additive is as shown in Table 2.
  • honeycomb sintered body was manufactured as follows.
  • the obtained kneaded material was extruded to form a honeycomb structure with an extrusion molding machine, and then dried with a hot air dryer, and then the resulting molded body was fired at 1600 ° C. to obtain a honeycomb sintered body. Obtained.
  • honeycomb sintered body The obtained honeycomb sintered bodies were measured for porosity, bending strength, thermal expansion coefficient, crystal orientation, and thermal shock temperature as follows.
  • FIG. 3 is a perspective view showing the honeycomb sintered body. As shown in FIG. 3, the honeycomb sintered body 1 has 8 ⁇ 8 cells, and the end face 1a has a size of 1.8 cm in length and 1.8 cm in width. An arrow A indicates the extrusion direction, and an arrow B indicates a direction perpendicular to the extrusion direction A.
  • the porosity was measured by cutting a portion corresponding to 2 ⁇ 2 cells from the center portion 2 of the above 8 ⁇ 8 cell honeycomb sintered body 1 so that the length along the extrusion direction A was about 2 cm. It was.
  • FIG. 4 is a perspective view showing the measurement sample 3. Using the measurement sample 3 shown in FIG. 4, the porosity was measured according to JIS R1634.
  • the length along the extrusion direction A from the central portion 2 of the 8 ⁇ 8 cell honeycomb sintered body 1 is about 2 cm. It cut out so that it might become and it was set as the measurement sample 3.
  • the linear expansion coefficient in the extrusion direction A of the measurement sample 3 was measured according to JIS R1618.
  • a measurement sample is cut out from the central portion 2 of the honeycomb sintered body 1 so that the length along the direction B perpendicular to the extrusion direction A is about 2 cm, and the thermal expansion coefficient in the direction B perpendicular to the measurement sample is determined. It was measured.
  • FIG. 7 and 8 are perspective views showing the production of a measurement sample for measuring the X-ray diffraction of the extruded surface.
  • the region 4 including the end face 1a of the honeycomb sintered body 1 was cut out, and a measurement sample shown in FIG. 8 was produced.
  • the measurement sample 5 shown in FIG. 8 the X-ray diffraction of the extruded surface 5a of the measurement sample 5 was measured.
  • the (002) plane is a plane perpendicular to the C axis, and the high strength of the (002) plane means that the C axis is oriented.
  • Heat shock temperature Each of the obtained honeycomb sintered bodies was held in an electric furnace for 30 minutes at a predetermined temperature, and then introduced into water, and the maximum temperature at which no cracks occurred was defined as the thermal shock temperature.
  • the predetermined temperature to be heated was a temperature every 50 ° C. within a range of 500 ° C. to 1200 ° C.
  • the honeycomb sintered bodies (honeycomb filters) of Examples 1 to 9 according to the present invention can have a low thermal expansion coefficient in the vertical direction while maintaining a high porosity, and can be sintered.
  • the strength of the bonded body can be improved. For this reason, it can be seen that a high thermal shock temperature can be obtained and the thermal shock resistance is excellent.
  • the honeycomb structure when the honeycomb structure is extruded, the granular aluminum titanate particles are arranged between the columnar aluminum titanate particles oriented in the extrusion direction and the pore former, thereby impairing the crystal orientation. It seems that the linear thermal expansion coefficient in the vertical direction can be reduced. Alternatively, it is considered that by mixing granular aluminum titanate with columnar aluminum titanate, the honeycomb sintered body becomes dense and high strength can be obtained.
  • Comparative Example 8 in which the major axis diameter of the granular aluminum titanate is larger than the minor axis diameter of the columnar aluminum titanate, the orientation of the columnar aluminum titanate is hindered by the granular aluminum titanate. The overlap of is reduced. For this reason, the strength is low. Moreover, since the sinterability is poor, the coefficient of thermal expansion in the direction perpendicular to the extrusion direction is high.
  • columnar aluminum titanate and granular aluminum titanate are mixed so that the weight ratio of columnar aluminum titanate: particulate aluminum titanate is within the range of 95: 5 to 60:40.
  • Honeycomb sintered body honeycomb filter
  • DESCRIPTION OF SYMBOLS 1a End face of honeycomb sintered body 2 ... Center part of honeycomb sintered body 3 .
  • Measurement sample cut out from honeycomb sintered body 4 ... Region in the vicinity of end face of honeycomb sintered body 5 .
  • Extruded surface of honeycomb sintered body X Sample 5a extruded surface for measuring line diffraction

Abstract

Disclosed is a honeycomb filter which is composed of aluminum titanate and has low thermal expansion coefficient, high porosity, high strength and excellent thermal shock resistance. Specifically disclosed is a honeycomb filter composed of aluminum titanate, which is characterized in that columnar aluminum titanate particles having an aspect ratio (= number average length of major axis/number average width of minor axis) of 1.3 or more and granular aluminum titanate particles having an aspect ratio (= number average length of major axis/number average width of minor axis) of less than 1.3 are used by being mixed at a weight ratio of the columnar aluminum titanate particles to the granular aluminum titanate particles within the range from 95:5 to 60:40. The honeycomb filter is also characterized in that the number average length of the major axes of the granular aluminum titanate particles is smaller than the number average width of the minor axes of the columnar aluminum titanate particles.

Description

ハニカムフィルタHoneycomb filter
　本発明は、チタン酸アルミニウムからなるハニカムフィルタに関するものである。 The present invention relates to a honeycomb filter made of aluminum titanate.
　チタン酸アルミニウムは、低熱膨張性で耐熱衝撃性に優れ、かつ融点が高いため、自動車の排ガス処理用触媒担体や、ディーゼルパティキュレートフィルタ（ＤＰＦ）等に用いられる多孔質材料として期待され、種々の開発が行われている。 Aluminum titanate is expected to be a porous material used in automobile exhaust gas treatment catalyst carriers, diesel particulate filters (DPFs), etc. because of its low thermal expansion, excellent thermal shock resistance, and high melting point. Development is underway.
　特許文献１においては、チタン酸アルミニウムが有する高融点、低熱膨張性を損なうことなく、高強度を有し、繰り返しの熱履歴に対して機械的強度の劣化が少ないチタン酸アルミニウム焼結体を得るため、チタン酸アルミニウムに、酸化マグネシウム及び酸化ケイ素を添加したものを焼結することが提案されている。 In Patent Document 1, an aluminum titanate sintered body having high strength and less mechanical strength deterioration with respect to repeated thermal history is obtained without impairing the high melting point and low thermal expansion property of aluminum titanate. Therefore, it has been proposed to sinter aluminum titanate added with magnesium oxide and silicon oxide.
　特許文献２においては、柱状チタン酸アルミニウムを用いて排ガスフィルタを製造することが開示されており、柱状粒子の長手方向が負の熱膨張係数であるとき長手方向と垂直な方向が正の熱膨張係数であるか、あるいは柱状粒子の長手方向が正の熱膨張係数であるとき長手方向と垂直な方向が負の熱膨張係数である排ガスフィルタを製造することが提案されている。 Patent Document 2 discloses that an exhaust gas filter is manufactured using columnar aluminum titanate, and when the longitudinal direction of the columnar particles has a negative thermal expansion coefficient, the direction perpendicular to the longitudinal direction is positive thermal expansion. It has been proposed to manufacture an exhaust gas filter that has a coefficient or a negative thermal expansion coefficient in the direction perpendicular to the longitudinal direction when the longitudinal direction of the columnar particles has a positive thermal expansion coefficient.
　しかしながら、柱状チタン酸アルミニウムの具体的な製造方法については開示されていない。また、柱状チタン酸アルミニウムと粒状チタン酸アルミニウムを混合して用いることについても開示されていない。 However, a specific method for producing columnar aluminum titanate is not disclosed. Also, there is no disclosure of using a mixture of columnar aluminum titanate and granular aluminum titanate.
　チタン酸アルミニウムからなるハニカムフィルタにおいては、上述のように、低い熱膨張係数を有し、かつ高強度で、繰り返しの熱履歴に対して機械的強度の劣化が少ないことが求められると共に、高い気孔率が求められている。 In a honeycomb filter made of aluminum titanate, as described above, it has a low thermal expansion coefficient, is high in strength, and requires little deterioration in mechanical strength with respect to repeated thermal history. The rate is sought.
特開平１－２４９６５７号公報JP-A-1-249657 特開平９－２９０２３号公報JP-A-9-29023
　本発明の目的は、低い熱膨張係数を有し、気孔率が高く、かつ高強度で耐熱衝撃性に優れたハニカムフィルタを提供することにある。 An object of the present invention is to provide a honeycomb filter having a low thermal expansion coefficient, a high porosity, high strength and excellent thermal shock resistance.
　本発明は、チタン酸アルミニウムからなるハニカムフィルタであって、アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３以上である柱状チタン酸アルミニウムと、アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３未満である粒状チタン酸アルミニウムとを、柱状チタン酸アルミニウム：粒状チタン酸アルミニウムの重量比で、９５：５～６０：４０の範囲内の割合となるように混合して用い、粒状チタン酸アルミニウムの個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径よりも小さいことを特徴としている。 The present invention is a honeycomb filter made of aluminum titanate, wherein the columnar aluminum titanate having an aspect ratio (= number average major axis diameter / number average minor axis diameter) of 1.3 or more, and the aspect ratio (= number average) Granular aluminum titanate having a major axis diameter / number average minor axis diameter of less than 1.3 in a weight ratio of columnar aluminum titanate: particulate aluminum titanate within a range of 95: 5 to 60:40. The number average major axis diameter of granular aluminum titanate is smaller than the number average minor axis diameter of columnar aluminum titanate.
　本発明においては、上述のように、柱状チタン酸アルミニウムと粒状チタン酸アルミニウムとを上記の割合で混合して用い、粒状チタン酸アルミニウムの個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径よりも小さいことを特徴としている。これにより、低い熱膨張係数を有し、気孔率が高く、かつ高強度で、耐熱衝撃性に優れたハニカムフィルタとすることができる。 In the present invention, as described above, columnar aluminum titanate and granular aluminum titanate are mixed and used in the above ratio, and the number average major axis diameter of granular aluminum titanate is the number average short axis of columnar aluminum titanate. It is characterized by being smaller than the shaft diameter. Thereby, a honeycomb filter having a low thermal expansion coefficient, a high porosity, a high strength, and excellent thermal shock resistance can be obtained.
　柱状チタン酸アルミニウムは、押出成形により成形する際、柱状形状の長手方向が押出方向に平行に揃うように配列する。このため、低い熱膨張係数を有するＣ軸が配向し、押出方向におけるハニカムフィルタの熱膨張係数を低くすることができる。 When the columnar aluminum titanate is formed by extrusion, the columnar aluminum titanate is arranged so that the longitudinal direction of the columnar shape is aligned in parallel with the extrusion direction. For this reason, the C-axis having a low thermal expansion coefficient is oriented, and the thermal expansion coefficient of the honeycomb filter in the extrusion direction can be lowered.
　また、柱状チタン酸アルミニウムは、アスペクト比が大きいため、柱状チタン酸アルミニウム粒子同士が重なりやすくなり、高強度化することができる。また、アスペクト比が大きいため、気孔率を高めることができる。 In addition, since columnar aluminum titanate has a large aspect ratio, columnar aluminum titanate particles tend to overlap each other, and the strength can be increased. Further, since the aspect ratio is large, the porosity can be increased.
　しかしながら、柱状チタン酸アルミニウムを用いたハニカムフィルタは、押出方向に対して垂直な方向における熱膨張率が大きいため、押出方向と、押出方向に対して垂直な方向とにおいて、大きな熱膨張率の差を生じる。その結果、ハニカムフィルタとして強度は高いが、耐熱衝撃性に劣る。 However, since the honeycomb filter using columnar aluminum titanate has a large coefficient of thermal expansion in the direction perpendicular to the extrusion direction, there is a large difference in coefficient of thermal expansion between the extrusion direction and the direction perpendicular to the extrusion direction. Produce. As a result, the honeycomb filter has high strength but is inferior in thermal shock resistance.
　本発明においては、柱状チタン酸アルミニウムと、粒状チタン酸アルミニウムとを、上記の所定の範囲内の割合となるように混合して用いている。柱状チタン酸アルミニウムと粒状チタン酸アルミニウムを混合して用いることにより、柱状チタン酸アルミニウム粒子の間に粒状チタン酸アルミニウム粒子を配置することができ、押出方向に対して垂直な方向における熱膨張係数を低くすることができる。このため、押出方向における熱膨張係数と、これに垂直な方向における熱膨張係数との差を小さくすることができ、耐熱衝撃性を高めることができる。 In the present invention, columnar aluminum titanate and granular aluminum titanate are mixed and used so as to have a ratio within the above predetermined range. By mixing and using columnar aluminum titanate and granular aluminum titanate, granular aluminum titanate particles can be arranged between columnar aluminum titanate particles, and the coefficient of thermal expansion in the direction perpendicular to the extrusion direction can be obtained. Can be lowered. For this reason, the difference between the thermal expansion coefficient in the extrusion direction and the thermal expansion coefficient in the direction perpendicular thereto can be reduced, and the thermal shock resistance can be improved.
　また、粒状チタン酸アルミニウムを混合することにより、ハニカムフィルタにおけるチタン酸アルミニウムの構造を緻密化することができ、気孔率が高く、かつ強度が高いハニカムフィルタとすることができる。 Also, by mixing granular aluminum titanate, the structure of aluminum titanate in the honeycomb filter can be densified, and a honeycomb filter having high porosity and high strength can be obtained.
　粒状チタン酸アルミニウムの混合割合が少ないと、耐熱衝撃性及び強度が向上するという効果が十分に得られない。また、粒状チタン酸アルミニウムの混合割合が多すぎると、気孔率が減少すると共に、強度が低くなり、耐熱衝撃性も低下する。 If the mixing ratio of the granular aluminum titanate is small, the effect of improving the thermal shock resistance and strength cannot be obtained sufficiently. Moreover, when there are too many mixing ratios of granular aluminum titanate, a porosity will reduce, intensity | strength will become low and a thermal shock resistance will also fall.
　本発明において、粒状チタン酸アルミニウムは、その個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径よりも小さいものが用いられる。これにより、気孔率及び強度が高く、耐熱衝撃性に優れたハニカムフィルタとすることができる。粒状チタン酸アルミニウムの個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径より大きくなると、柱状チタン酸アルミニウム同士の重なりが減少し、強度が低下すると共に、焼結が進行しにくくなり、押出方向に対して垂直な方向における熱膨張係数の低減が十分にできなくなり、耐熱衝撃性が低下する。 In the present invention, granular aluminum titanate having a number average major axis diameter smaller than that of columnar aluminum titanate is used. Thereby, a honeycomb filter having high porosity and strength and excellent thermal shock resistance can be obtained. When the number average major axis diameter of the granular aluminum titanate is larger than the number average minor axis diameter of the columnar aluminum titanate, the overlap between the columnar aluminum titanates decreases, the strength decreases, and the sintering becomes difficult to proceed. The thermal expansion coefficient in the direction perpendicular to the extrusion direction cannot be sufficiently reduced, and the thermal shock resistance is lowered.
　本発明における柱状チタン酸アルミニウムは、チタン源、アルミニウム源、及びマグネシウム源を含む原料をメカノケミカルに粉砕しながら混合し、粉砕した混合物を焼成することにより製造することができる。 The columnar aluminum titanate in the present invention can be produced by mixing raw materials containing a titanium source, an aluminum source, and a magnesium source while pulverizing them into mechanochemicals and firing the pulverized mixture.
　マグネシウム源を、チタン源及びアルミニウム源の合計に対しそれぞれの酸化物換算で、０．５～２．０重量％の範囲内となるように混合した原料を用いることが好ましい。マグネシウム源の混合割合をこのような範囲内とすることにより、平均アスペクト比が１．３以上である柱状チタン酸アルミニウムが得られやすくなる。 It is preferable to use a raw material in which a magnesium source is mixed so as to be within a range of 0.5 to 2.0% by weight in terms of respective oxides with respect to the total of the titanium source and the aluminum source. By setting the mixing ratio of the magnesium source in such a range, columnar aluminum titanate having an average aspect ratio of 1.3 or more is easily obtained.
　粉砕混合物を焼成する温度としては、１３００～１６００℃の範囲内の温度であることが好ましい。このような温度範囲内で焼成することにより、本発明の柱状チタン酸アルミニウムをより効率的に製造することができる。 The temperature for firing the pulverized mixture is preferably a temperature in the range of 1300 to 1600 ° C. By firing within such a temperature range, the columnar aluminum titanate of the present invention can be produced more efficiently.
　焼成時間は、特に限定されるものではないが、０．５時間～２０時間の範囲内で行うことが好ましい。 Calcination time is not particularly limited, but it is preferably performed within a range of 0.5 hours to 20 hours.
　メカノケミカルな粉砕としては、物理的な衝撃を与えながら粉砕する方法が挙げられる。具体的には、振動ミルによる粉砕が挙げられる。振動ミルによる粉砕処理を行うことにより、混合粉体の摩砕による剪断応力によって、原子配列の乱れと原子間距離の減少が同時に起こり、異種粒子の接点部分の原子移動が起こる結果、準安定相が得られると考えられる。これにより、反応活性の高い粉砕混合物が得られ、この反応活性の高い粉砕混合物を焼成することにより、上記本発明の柱状チタン酸アルミニウムを製造することができる。 Mechanochemical crushing includes a method of crushing while giving a physical impact. Specifically, pulverization by a vibration mill can be mentioned. By pulverizing with a vibration mill, the disruption of atomic arrangement and the decrease in interatomic distance occur simultaneously due to the shear stress caused by the grinding of the mixed powder, resulting in atomic movement of the contact part of different particles, resulting in a metastable phase. Can be obtained. Thereby, a pulverized mixture with high reaction activity is obtained, and the columnar aluminum titanate of the present invention can be produced by firing the pulverized mixture with high reaction activity.
　本発明におけるメカノケミカルな粉砕は、一般に、水や溶剤を用いない乾式処理として行われる。 The mechanochemical pulverization in the present invention is generally performed as a dry process without using water or a solvent.
　メカノケミカルな粉砕による混合処理の時間は特に限定されるものではないが、一般には０．１時間～６時間の範囲内であることが好ましい。 The mixing treatment time by mechanochemical pulverization is not particularly limited, but generally it is preferably within the range of 0.1 to 6 hours.
　本発明において用いる原料には、チタン源、アルミニウム源、及びマグネシウム源が含まれる。チタン源としては、酸化チタンを含有する化合物を用いることができ、具体的には、酸化チタン、ルチル鉱石、水酸化チタンウェットケーキ、含水チタニアなどが挙げられる。 The raw materials used in the present invention include a titanium source, an aluminum source, and a magnesium source. As the titanium source, a compound containing titanium oxide can be used. Specific examples include titanium oxide, rutile ore, titanium hydroxide wet cake, and hydrous titania.
　アルミニウム源としては、加熱により酸化アルミニウムを生じる化合物を用いることができ、具体的には、酸化アルミニウム、水酸化アルミニウム、硫酸アルミニウムなどが挙げられる。これらの中でも、特に酸化アルミニウムが好ましく用いられる。 As the aluminum source, a compound that generates aluminum oxide by heating can be used. Specific examples include aluminum oxide, aluminum hydroxide, and aluminum sulfate. Among these, aluminum oxide is particularly preferably used.
　チタン源とアルミニウム源の混合割合としては、Ｔｉ：Ａｌ＝１：２（モル比）の割合を基本とするが、それぞれ±１０％程度であれば変化させても支障はない。 The mixing ratio of the titanium source and the aluminum source is basically a ratio of Ti: Al = 1: 2 (molar ratio), but there is no problem even if it is changed within about ± 10%.
　マグネシウム源としては、加熱により酸化マグネシウムを生じる化合物を用いることができ、具体的には、水酸化マグネシウム、酸化マグネシウム、炭酸マグネシウムなどが挙げられる。これらの中でも、特に水酸化マグネシウム及び酸化マグネシウムが好ましく用いられる。 As the magnesium source, a compound that generates magnesium oxide by heating can be used, and specific examples include magnesium hydroxide, magnesium oxide, and magnesium carbonate. Among these, magnesium hydroxide and magnesium oxide are particularly preferably used.
　また、原料中にケイ素源がさらに含まれていても良い。 Further, the raw material may further contain a silicon source.
　ケイ素源が含有させることにより、チタン酸アルミニウムの分解を抑制することができ、高温安定性に優れた柱状チタン酸アルミニウムを製造することができる。 By including the silicon source, decomposition of aluminum titanate can be suppressed, and columnar aluminum titanate excellent in high-temperature stability can be produced.
　ケイ素源としては、酸化ケイ素、ケイ素などが挙げられる。これらの中でも、特に酸化ケイ素が好ましく用いられる。ケイ素源の原料中における含有量は、チタン源及びアルミニウム源の合計に対してそれぞれの酸化物換算で、０．５～１０重量％の範囲内であることが好ましい。このような範囲内とすることにより、柱状チタン酸アルミニウムをより安定して製造することができる。 Examples of the silicon source include silicon oxide and silicon. Among these, silicon oxide is particularly preferably used. The content of the silicon source in the raw material is preferably in the range of 0.5 to 10% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. By setting it within such a range, columnar aluminum titanate can be more stably produced.
　本発明の粒状チタン酸アルミニウムは、例えば、従来から公知の製造方法により製造することができる。また、チタン源、アルミニウム源、及びマグネシウム源を含む原料をメカノケミカルに粉砕しながら混合し、粉砕した混合物を焼成することによっても製造することができる。この場合、マグネシウム源の混合割合は、チタン源及びアルミニウム源の合計に対してそれぞれの酸化物換算で、２．０重量％より多くなるように混合することが好ましい。また、原料をメカノケミカルに粉砕せずに混合することによっても、粒状チタン酸アルミニウムを製造することができる。 The granular aluminum titanate of the present invention can be produced by, for example, a conventionally known production method. Moreover, it can manufacture also by mixing the raw material containing a titanium source, an aluminum source, and a magnesium source, grind | pulverizing mechanochemically, and baking the grind | pulverized mixture. In this case, the mixing ratio of the magnesium source is preferably mixed so as to be more than 2.0% by weight in terms of the respective oxides with respect to the total of the titanium source and the aluminum source. Moreover, granular aluminum titanate can also be produced by mixing raw materials into mechanochemicals without grinding.
　粒状チタン酸アルミニウムを製造する場合のアルミニウム源及びシリカ源の混合割合は、柱状チタン酸アルミニウムを製造する場合と同様の割合とすることができる。 The mixing ratio of the aluminum source and the silica source when producing the granular aluminum titanate can be the same ratio as when producing the columnar aluminum titanate.
　本発明におけるチタン酸アルミニウムのアスペクト比は、上述のように個数平均長軸径／個数平均短軸径の比から求められる値である。個数平均長軸径及び個数平均短軸径は、例えば、フロー式粒子像分析装置により測定することができる。 The aspect ratio of aluminum titanate in the present invention is a value determined from the ratio of number average major axis diameter / number average minor axis diameter as described above. The number average major axis diameter and the number average minor axis diameter can be measured by, for example, a flow particle image analyzer.
　本発明における柱状チタン酸アルミニウムの個数平均長軸径は、７～１７μｍの範囲内であることが好ましく、個数平均短軸径は、５～１０μｍの範囲であることが好ましい。 The number average major axis diameter of the columnar aluminum titanate in the present invention is preferably in the range of 7 to 17 μm, and the number average minor axis diameter is preferably in the range of 5 to 10 μm.
　また、粒状チタン酸アルミニウムの個数平均長軸径は、０．１～１０μｍの範囲内であることが好ましく、個数平均短軸径は、０．１～１０μｍの範囲内であることが好ましい。 The number average major axis diameter of the granular aluminum titanate is preferably in the range of 0.1 to 10 μm, and the number average minor axis diameter is preferably in the range of 0.1 to 10 μm.
　上述のように、粒状チタン酸アルミニウムの個数平均長軸径は、柱状チタン酸アルミニウムの個数平均短軸径よりも小さくなるように、粒状チタン酸アルミニウム及び柱状チタン酸アルミニウムが選ばれる。 As described above, granular aluminum titanate and columnar aluminum titanate are selected so that the number average major axis diameter of granular aluminum titanate is smaller than the number average minor axis diameter of columnar aluminum titanate.
　本発明における柱状チタン酸アルミニウムのアスペクト比は、好ましくは１．３～５．０の範囲内であり、さらに好ましくは１．３～２．５の範囲内であり、さらに好ましくは１．３～２．０の範囲内である。 The aspect ratio of the columnar aluminum titanate in the present invention is preferably in the range of 1.3 to 5.0, more preferably in the range of 1.3 to 2.5, and still more preferably in the range of 1.3 to Within the range of 2.0.
　本発明における粒状チタン酸アルミニウムのアスペクト比は、１．２以下であることが好ましく、さらに好ましくは１．１～１．０の範囲内である。 The aspect ratio of the granular aluminum titanate in the present invention is preferably 1.2 or less, and more preferably in the range of 1.1 to 1.0.
　本発明のハニカムフィルタは、柱状チタン酸アルミと粒状チタン酸アルミとを上述のようにして混合して用いることにより、押出方向に対して垂直な方向における３０～８００℃の間の熱膨張係数を低くすることができ、押出方向の熱膨張係数と、これに垂直な方向における熱膨張係数の差を小さくすることができ、耐熱衝撃性に優れたハニカムフィルタとすることができる。 In the honeycomb filter of the present invention, columnar aluminum titanate and granular aluminum titanate are mixed and used as described above, so that the thermal expansion coefficient between 30 and 800 ° C. in the direction perpendicular to the extrusion direction can be obtained. The difference between the thermal expansion coefficient in the extrusion direction and the thermal expansion coefficient in the direction perpendicular thereto can be reduced, and a honeycomb filter having excellent thermal shock resistance can be obtained.
　本発明のハニカムフィルタは、押出成形により成形された成形体を焼成することよって得られるハニカムフィルタであり、押出方向に対して垂直な方向における３０～８００℃の間の熱膨張係数が、２．０×１０－６／℃以下であることを特徴としている。 The honeycomb filter of the present invention is a honeycomb filter obtained by firing a molded body formed by extrusion, and has a thermal expansion coefficient of 2 to 30 ° C. in a direction perpendicular to the extrusion direction. It is characterized by being 0 × 10 −6 / ° C. or less.
　押出方向に対して垂直な方向における熱膨張係数は、さらに好ましくは、０．０～１．５×１０－６／℃の範囲である。 The coefficient of thermal expansion in the direction perpendicular to the extrusion direction is more preferably in the range of 0.0 to 1.5 × 10 −6 / ° C.
　また、本発明のハニカムフィルタの押出方向における３０～８００℃の間の熱膨張係数は、０．０×１０－６／℃以下であることが好ましく、さらに好ましくは－２．０～０．０×１０－６／℃の範囲である。 The thermal expansion coefficient between 30 and 800 ° C. in the extrusion direction of the honeycomb filter of the present invention is preferably 0.0 × 10 −6 / ° C. or less, more preferably −2.0 to 0.0. The range is × 10 -6 / ° C.
　本発明のハニカムフィルタは、柱状チタン酸アルミニウム及び粒状チタン酸アルミニウムの混合物に、例えば、造孔剤、バインダー、分散剤、及び水を添加した混合組成物を作製し、これを、例えば押出成形機を用いてハニカム構造体となるように成形し、セルの開口が市松模様となるように片側の目封止を行った後、乾燥して得られた成形体を焼成して製造することができる。焼成温度としては、例えば、１４００～１６００℃が挙げられる。 The honeycomb filter of the present invention is a mixture of columnar aluminum titanate and granular aluminum titanate prepared by adding, for example, a pore-forming agent, a binder, a dispersant, and water. Can be manufactured by firing the molded body obtained by drying after plugging on one side so that the cell opening has a checkered pattern. . Examples of the firing temperature include 1400 to 1600 ° C.
　造孔剤としては、黒鉛、グラファイト、木粉、ポリエチレンが挙げられる。また、バインダーとしては、メチルセルロース、エチルセルロース、ポリビニルアルコールが挙げられる。分散剤としては、脂肪酸石鹸、エチレングリコールが挙げられる。造孔剤、バインダー、分散剤、及び水の量は適宜調整することができる。 Examples of pore-forming agents include graphite, graphite, wood powder, and polyethylene. Examples of the binder include methyl cellulose, ethyl cellulose, and polyvinyl alcohol. Examples of the dispersant include fatty acid soap and ethylene glycol. The amount of pore-forming agent, binder, dispersant, and water can be adjusted as appropriate.
　本発明によれば、低い熱膨張係数を有し、気孔率が高く、かつ高強度で、耐熱衝撃性に優れたハニカムフィルタとすることができる。 According to the present invention, a honeycomb filter having a low thermal expansion coefficient, high porosity, high strength, and excellent thermal shock resistance can be obtained.
図１は、本発明に従う実施例において用いられた柱状チタン酸アルミニウムを示す走査型電子顕微鏡写真である。FIG. 1 is a scanning electron micrograph showing columnar aluminum titanate used in an example according to the present invention. 図２は、本発明に従う実施例において用いられた粒状チタン酸アルミニウムを示す走査型電子顕微鏡写真である。FIG. 2 is a scanning electron micrograph showing granular aluminum titanate used in the examples according to the present invention. 図３は、ハニカム焼結体を示す斜視図である。FIG. 3 is a perspective view showing the honeycomb sintered body. 図４は、ハニカム焼結体から切り出した測定サンプルを示す斜視図である。FIG. 4 is a perspective view showing a measurement sample cut out from the honeycomb sintered body. 図５は、ハニカム焼結体の曲げ強度の測定方法を説明するための模式図である。FIG. 5 is a schematic diagram for explaining a method for measuring the bending strength of a honeycomb sintered body. 図６は、ハニカム焼結体から切り出した測定サンプルを示す斜視図である。FIG. 6 is a perspective view showing a measurement sample cut out from the honeycomb sintered body. 図７は、ハニカム焼結体を示す斜視図である。FIG. 7 is a perspective view showing a honeycomb sintered body. 図８は、ハニカム焼結体から切り出した押出面のＸ線回折を測定するための測定サンプルを示す斜視図である。FIG. 8 is a perspective view showing a measurement sample for measuring the X-ray diffraction of the extruded surface cut out from the honeycomb sintered body. 図９は、本発明に従う実施例で得られた柱状チタン酸アルミニウムのＸ線回折チャートを示す図である。FIG. 9 is a diagram showing an X-ray diffraction chart of columnar aluminum titanate obtained in an example according to the present invention.
　以下、本発明を具体的な実施例により詳細に説明するが、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described in detail with specific examples, but the present invention is not limited to the following examples.
　〔柱状チタン酸アルミニウムの製造方法〕
　（製造例１）
　酸化チタン３６０．０ｇ、酸化アルミニウム４１１．１ｇ、水酸化マグネシウム９．７ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 [Method for producing columnar aluminum titanate]
(Production Example 1)
360.0 g of titanium oxide, 411.1 g of aluminum oxide, 9.7 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合粉５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。得られた生成物について、Ｘ線回折にて結晶相を同定したところ、Ａｌ２ＴｉＯ５であった。 500 g of the pulverized mixed powder obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace. The obtained product was identified crystalline phases by X-ray diffraction, it was Al 2 TiO 5.
　また、得られた生成物について走査型電子顕微鏡（ＳＥＭ）にて形状を確認した。また、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。表１に組成、形状、個数平均長軸径、個数平均短軸径、及びアスペクト比を示す。 Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM). Further, the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. Table 1 shows the composition, shape, number average major axis diameter, number average minor axis diameter, and aspect ratio.
　図１は、本製造例で得られた柱状チタン酸アルミニウムを示すＳＥＭ写真である。 FIG. 1 is an SEM photograph showing the columnar aluminum titanate obtained in this production example.
　図９は、本製造例において得られた柱状チタン酸アルミニウムのＸ線回折チャートを示す図である。 FIG. 9 is a view showing an X-ray diffraction chart of the columnar aluminum titanate obtained in this production example.
　（製造例２）
　酸化チタン３５４．７ｇ、酸化アルミニウム４０５．０ｇ、水酸化マグネシウム２１．３ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 (Production Example 2)
354.7 g of titanium oxide, 405.0 g of aluminum oxide, 21.3 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合粉５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。得られた生成物は、Ｘ線回折にて結晶相を同定したところ、Ａｌ２ＴｉＯ５であった。 500 g of the pulverized mixed powder obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace. As a result of identifying the crystal phase by X-ray diffraction, the obtained product was Al 2 TiO 5 .
　また、得られた生成物について走査型電子顕微鏡（ＳＥＭ）にて形状を確認した。また、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。表１に組成、形状、個数平均長軸径、個数平均短軸径、及びアスペクト比を示す。 Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM). Further, the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. Table 1 shows the composition, shape, number average major axis diameter, number average minor axis diameter, and aspect ratio.
　〔粒状チタン酸アルミニウムの製造〕
　（製造例３）
　酸化チタン３４０．１ｇ、酸化アルミニウム３８８．３ｇ、水酸化マグネシウム５２．６ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 [Production of granular aluminum titanate]
(Production Example 3)
340.1 g of titanium oxide, 388.3 g of aluminum oxide, 52.6 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合粉５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。得られた生成物は、Ｘ線回折にて結晶相を同定したところ、Ａｌ２ＴｉＯ５であった。 500 g of the pulverized mixed powder obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace. As a result of identifying the crystal phase by X-ray diffraction, the obtained product was Al 2 TiO 5 .
　また、得られた生成物について走査型電子顕微鏡（ＳＥＭ）にて形状を確認した。また、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。表１に組成、形状、個数平均長軸径、個数平均短軸径、及びアスペクト比を示す。 Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM). Further, the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. Table 1 shows the composition, shape, number average major axis diameter, number average minor axis diameter, and aspect ratio.
　図２は、本製造例で得られた粒状チタン酸アルミニウムを示すＳＥＭ写真である。 FIG. 2 is an SEM photograph showing the granular aluminum titanate obtained in this production example.
　（製造例４）
　酸化チタン３４０．１ｇ、酸化アルミニウム３８８．３ｇ、水酸化マグネシウム５２．６ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 (Production Example 4)
340.1 g of titanium oxide, 388.3 g of aluminum oxide, 52.6 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合粉５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。更に、生成物を自動乳鉢にて１２時間粉砕して粒径を調整した。得られた生成物は、Ｘ線回折にて結晶相を同定したところ、Ａｌ２ＴｉＯ５であった。 500 g of the pulverized mixed powder obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace. Further, the product was pulverized in an automatic mortar for 12 hours to adjust the particle size. As a result of identifying the crystal phase by X-ray diffraction, the obtained product was Al 2 TiO 5 .
　また、得られた生成物について走査型電子顕微鏡（ＳＥＭ）にて形状を確認した。また、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。表１に組成、形状、個数平均長軸径、個数平均短軸径、及びアスペクト比を示す。 Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM). Further, the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. Table 1 shows the composition, shape, number average major axis diameter, number average minor axis diameter, and aspect ratio.
　（製造例５）
　酸化チタン３４０．１ｇ、酸化アルミニウム３８８．３ｇ、水酸化マグネシウム５２．６ｇ、及び酸化ケイ素１９．０ｇを振動ミルにて粉砕しながら、２．０時間混合した。 (Production Example 5)
340.1 g of titanium oxide, 388.3 g of aluminum oxide, 52.6 g of magnesium hydroxide, and 19.0 g of silicon oxide were mixed for 2.0 hours while being pulverized with a vibration mill.
　以上のようにして得られた粉砕混合粉５００ｇをルツボに充填し、電気炉にて１５００℃で４時間焼成した。更に、生成物を自動乳鉢にて１００時間粉砕して粒径調整を行った。得られた生成物は、Ｘ線回折にて結晶相を同定したところ、Ａｌ２ＴｉＯ５であった。 500 g of the pulverized mixed powder obtained as described above was charged in a crucible and baked at 1500 ° C. for 4 hours in an electric furnace. Furthermore, the particle size was adjusted by pulverizing the product in an automatic mortar for 100 hours. As a result of identifying the crystal phase by X-ray diffraction, the obtained product was Al 2 TiO 5 .
　また、得られた生成物について走査型電子顕微鏡（ＳＥＭ）にて形状を確認した。また、フロー式粒子像分析にてアスペクト比（＝個数平均長軸径／個数平均短軸径）を測定した。表１に組成、形状、個数平均長軸径、個数平均短軸径、及びアスペクト比を示す。 Further, the shape of the obtained product was confirmed with a scanning electron microscope (SEM). Further, the aspect ratio (= number average major axis diameter / number average minor axis diameter) was measured by flow particle image analysis. Table 1 shows the composition, shape, number average major axis diameter, number average minor axis diameter, and aspect ratio.
　製造例１～５で得られたチタン酸アルミニウムの組成、形状、長軸径（個数平均長軸径）、短軸径（個数平均短軸径）、アスペクト比を表１に示す。 Table 1 shows the composition, shape, major axis diameter (number average major axis diameter), minor axis diameter (number average minor axis diameter), and aspect ratio of the aluminum titanates obtained in Production Examples 1 to 5.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、製造例１及び２で得られたチタン酸アルミニウムは、アスペクト比が１．３以上の柱状チタン酸アルミニウムである。また、製造例３～５により得られたチタン酸アルミニウムは、アスペクト比が１．３未満の粒状チタン酸アルミニウムである。 As shown in Table 1, the aluminum titanate obtained in Production Examples 1 and 2 is a columnar aluminum titanate having an aspect ratio of 1.3 or more. Further, the aluminum titanate obtained in Production Examples 3 to 5 is granular aluminum titanate having an aspect ratio of less than 1.3.
　〔ハニカム焼結体の製造〕
　表２に示すように、実施例１～９及び比較例６～８については、ベース材のチタン酸アルミニウムと、添加材のチタン酸アルミニウムを混合して用い、ハニカム焼結体を製造した。実施例１～９においては、製造例１または２の柱状チタン酸アルミニウムをベース材とし、製造例４または５の粒状チタン酸アルミニウムを添加材として用いた。 [Manufacture of honeycomb sintered body]
As shown in Table 2, in Examples 1 to 9 and Comparative Examples 6 to 8, honeycomb sintered bodies were manufactured by using a mixture of aluminum titanate as a base material and aluminum titanate as an additive. In Examples 1 to 9, the columnar aluminum titanate of Production Example 1 or 2 was used as a base material, and the granular aluminum titanate of Production Example 4 or 5 was used as an additive.
　比較例６～８においては、製造例１または２の柱状チタン酸アルミニウムをベース材として用い、製造例３～５のいずれかの粒状チタン酸アルミニウムを添加材として用いた。 In Comparative Examples 6 to 8, the columnar aluminum titanate of Production Example 1 or 2 was used as a base material, and the granular aluminum titanate of Production Examples 3 to 5 was used as an additive.
　比較例１～５においては、ベース材のみを用い、ベース材として製造例１～２の柱状チタン酸アルミニウムまたは製造例３～５の粒状チタン酸アルミニウムを用いた。 In Comparative Examples 1 to 5, only the base material was used, and the columnar aluminum titanate of Production Examples 1 and 2 or the granular aluminum titanate of Production Examples 3 to 5 were used as the base material.
　ベース材と添加材の混合比は、表２に示す通りである。 The mixing ratio of the base material and the additive is as shown in Table 2.
　上記のチタン酸アルミニウムを用いて、以下のようにしてハニカム焼結体を製造した。 Using the above aluminum titanate, a honeycomb sintered body was manufactured as follows.
　チタン酸アルミニウム１００重量部に対し、黒鉛２０重量部、メチルセルロース１０重量部、脂肪酸石鹸０．５重量部を配合し、さらに水を適当量添加して混練し、押出成形可能な坏土を得た。 Compounding 20 parts by weight of graphite, 10 parts by weight of methyl cellulose and 0.5 parts by weight of fatty acid soap with respect to 100 parts by weight of aluminum titanate, adding an appropriate amount of water and kneading to obtain an extrudable clay. .
　得られた坏土を押出成形機にてハニカム構造体となるように押し出して成形し、次に熱風乾燥機で乾燥した後、得られた成形体を１６００℃で焼成し、ハニカム焼結体を得た。 The obtained kneaded material was extruded to form a honeycomb structure with an extrusion molding machine, and then dried with a hot air dryer, and then the resulting molded body was fired at 1600 ° C. to obtain a honeycomb sintered body. Obtained.
　〔ハニカム焼結体の評価〕
　得られた各ハニカム焼結体について気孔率、曲げ強度、熱膨張係数、結晶配向度、及び耐熱衝撃温度を以下のようにして測定した。 [Evaluation of honeycomb sintered body]
The obtained honeycomb sintered bodies were measured for porosity, bending strength, thermal expansion coefficient, crystal orientation, and thermal shock temperature as follows.
　（気孔率）
　図３は、ハニカム焼結体を示す斜視図である。図３に示すように、ハニカム焼結体１は、８×８セルを有し、端面１ａは、縦１．８ｃｍ、横１．８ｃｍの大きさを有している。矢印Ａは、押出方向を示しており、矢印Ｂは押出方向Ａに対し垂直な方向を示している。 (Porosity)
FIG. 3 is a perspective view showing the honeycomb sintered body. As shown in FIG. 3, the honeycomb sintered body 1 has 8 × 8 cells, and the end face 1a has a size of 1.8 cm in length and 1.8 cm in width. An arrow A indicates the extrusion direction, and an arrow B indicates a direction perpendicular to the extrusion direction A.
　気孔率は、上記の８×８セルのハニカム焼結体１の中心部２から、２×２セルに相当する部分を、押出方向Ａに沿う長さが２ｃｍ程度となるように切り出し、測定サンプルとした。 The porosity was measured by cutting a portion corresponding to 2 × 2 cells from the center portion 2 of the above 8 × 8 cell honeycomb sintered body 1 so that the length along the extrusion direction A was about 2 cm. It was.
　図４は、測定サンプル３を示す斜視図である。図４に示す測定サンプル３を用い、ＪＩＳ　Ｒ１６３４に準拠して気孔率を測定した。 FIG. 4 is a perspective view showing the measurement sample 3. Using the measurement sample 3 shown in FIG. 4, the porosity was measured according to JIS R1634.
　（曲げ強度）
　図５に示すように、上記の８×８セルのハニカム焼結体１を、支持点１１及び１２に支持した状態で、焼結体１の中心部を押圧棒１０で押圧することにより、ＪＩＳ　Ｒ１６０１に準拠して、曲げ強度を測定した。 (Bending strength)
As shown in FIG. 5, the 8 × 8 cell honeycomb sintered body 1 is supported by the support points 11 and 12, and the center portion of the sintered body 1 is pressed with a pressing rod 10, thereby JIS. The bending strength was measured according to R1601.
　（熱膨張係数）
　図３及び図４を参照して説明した、気孔率の測定サンプル３と同様にして、８×８セルのハニカム焼結体１の中心部２から、押出方向Ａに沿う長さが２ｃｍ程度となるように切り出し、測定サンプル３とした。図６に示すように、測定サンプル３の押出方向Ａにおける線膨張係数を、ＪＩＳ　Ｒ１６１８に準拠して測定した。同様に、押出方向Ａと垂直な方向Ｂに沿う長さが２ｃｍ程度となるようにハニカム焼結体１の中心部２から測定サンプルを切り出し、この測定サンプルの垂直な方向Ｂにおける熱膨張係数を測定した。 (Coefficient of thermal expansion)
Similar to the porosity measurement sample 3 described with reference to FIGS. 3 and 4, the length along the extrusion direction A from the central portion 2 of the 8 × 8 cell honeycomb sintered body 1 is about 2 cm. It cut out so that it might become and it was set as the measurement sample 3. As shown in FIG. 6, the linear expansion coefficient in the extrusion direction A of the measurement sample 3 was measured according to JIS R1618. Similarly, a measurement sample is cut out from the central portion 2 of the honeycomb sintered body 1 so that the length along the direction B perpendicular to the extrusion direction A is about 2 cm, and the thermal expansion coefficient in the direction B perpendicular to the measurement sample is determined. It was measured.
　（結晶配向度）
　結晶配向度は、ハニカム焼結体の押出面のＸ線回折を測定し、（００２）面の回折ピーク強度（＝Ｉ（００２））及び（２３０）面の回折ピーク強度（＝Ｉ（２３０））より、以下の式により算出した。 (Crystal orientation)
The degree of crystal orientation is determined by measuring the X-ray diffraction of the extruded surface of the honeycomb sintered body, and the diffraction peak intensity (= I (002)) on the (002) plane and the diffraction peak intensity (= I (230) on the (230) plane. ) From the following formula.
　結晶配向度＝Ｉ（００２）／｛Ｉ（００２）＋Ｉ（２３０）｝
　なお、（００２）面の回折強度は、２θ＝５０．８°付近に現れるピークであり、（２３０）面の回折ピークは、２θ＝３３．７°付近に現れるピークである。 Degree of crystal orientation = I (002) / {I (002) + I (230)}
The diffraction intensity of the (002) plane is a peak appearing near 2θ = 50.8 °, and the diffraction peak of the (230) plane is a peak appearing near 2θ = 33.7 °.
　図７及び図８は、押出面のＸ線回折を測定するための測定サンプルの作製を示す斜視図である。 7 and 8 are perspective views showing the production of a measurement sample for measuring the X-ray diffraction of the extruded surface.
　図７に示すように、ハニカム焼結体１の端面１ａを含む領域４を切り取り、図８に示す測定サンプルを作製した。図８に示す測定サンプル５を用い、この測定サンプル５の押出面５ａのＸ線回折を測定した。 As shown in FIG. 7, the region 4 including the end face 1a of the honeycomb sintered body 1 was cut out, and a measurement sample shown in FIG. 8 was produced. Using the measurement sample 5 shown in FIG. 8, the X-ray diffraction of the extruded surface 5a of the measurement sample 5 was measured.
　なお、（００２）面はＣ軸に垂直な面であり、（００２）面の強度が高いということは、Ｃ軸が配向していることを意味する。 Note that the (002) plane is a plane perpendicular to the C axis, and the high strength of the (002) plane means that the C axis is oriented.
　（耐熱衝撃温度）
　得られた各ハニカム焼結体を、所定温度にて電気炉内で３０分間保持した後、水中へ導入し、ひび割れが生じない最高温度を耐熱衝撃温度とした。 (Heat shock temperature)
Each of the obtained honeycomb sintered bodies was held in an electric furnace for 30 minutes at a predetermined temperature, and then introduced into water, and the maximum temperature at which no cracks occurred was defined as the thermal shock temperature.
　なお、加熱する所定温度は５００℃～１２００℃の範囲内の５０℃毎の温度とした。 It should be noted that the predetermined temperature to be heated was a temperature every 50 ° C. within a range of 500 ° C. to 1200 ° C.
　以上のようにして測定した結果を、表２に示した。 The results of measurement as described above are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２に示すように、本発明に従う実施例１～９のハニカム焼結体（ハニカムフィルタ）は、高い気孔率を維持したままで、垂直方向における熱膨張係数を低くすることができ、かつ焼結体の強度を向上させることができる。このため、高い耐熱衝撃温度を得ることができ、耐熱衝撃性に優れていることがわかる。 As shown in Table 2, the honeycomb sintered bodies (honeycomb filters) of Examples 1 to 9 according to the present invention can have a low thermal expansion coefficient in the vertical direction while maintaining a high porosity, and can be sintered. The strength of the bonded body can be improved. For this reason, it can be seen that a high thermal shock temperature can be obtained and the thermal shock resistance is excellent.
　本発明に従うことにより、ハニカム構造体を押出成形する際、押出方向に配向した柱状チタン酸アルミニウム粒子と造孔剤との間に粒状チタン酸アルミニウム粒子が配置され、これによって結晶配向性を損なうことなく、垂直方向における線熱膨張係数を小さくすることができるものと思われる。または、粒状チタン酸アルミニウムを柱状チタン酸アルミニウムと混合することにより、ハニカム焼結体が緻密化し、高い強度が得られるものと思われる。 According to the present invention, when the honeycomb structure is extruded, the granular aluminum titanate particles are arranged between the columnar aluminum titanate particles oriented in the extrusion direction and the pore former, thereby impairing the crystal orientation. It seems that the linear thermal expansion coefficient in the vertical direction can be reduced. Alternatively, it is considered that by mixing granular aluminum titanate with columnar aluminum titanate, the honeycomb sintered body becomes dense and high strength can be obtained.
　柱状チタン酸アルミニウムを用いた比較例１及び２においては、高い強度及び高い気孔率が得られているが、垂直方向における熱膨張係数が大きくなっており、押出方向と、それに垂直な方向における熱膨張係数の差が大きくなるため、耐熱衝撃温度が低くなっている。 In Comparative Examples 1 and 2 using columnar aluminum titanate, high strength and high porosity are obtained, but the thermal expansion coefficient in the vertical direction is large, and the heat in the extrusion direction and the direction perpendicular thereto is obtained. Since the difference in the expansion coefficient is large, the thermal shock temperature is low.
　粒状チタン酸アルミニウムを用いた比較例３～５においては、押出方向と、それに垂直な方向における熱膨張係数の差が小さくなっているが、ハニカム焼結体の強度が非常に低いため、耐熱衝撃温度が低くなっている。また、チタン酸アルミニウムの粒子径が小さいほど、焼結の進行により熱膨張係数が小さくなっているが、同時に気孔率も減少するため、適切な焼結体が得られないことがわかる。 In Comparative Examples 3 to 5 using granular aluminum titanate, the difference in coefficient of thermal expansion between the extrusion direction and the direction perpendicular thereto is small, but the strength of the honeycomb sintered body is very low. The temperature is low. It can also be seen that the smaller the particle diameter of the aluminum titanate, the smaller the thermal expansion coefficient due to the progress of sintering, but at the same time the porosity also decreases, so that an appropriate sintered body cannot be obtained.
　比較例６及び７においては、粒状チタン酸アルミニウムの添加量が多いため、柱状チタン酸アルミニウム粒子同士の重なりが減少して、強度が低下すると共に、気孔率が低くなっている。 In Comparative Examples 6 and 7, since the amount of granular aluminum titanate added is large, the overlap between the columnar aluminum titanate particles is reduced, the strength is lowered, and the porosity is lowered.
　粒状チタン酸アルミニウムの長軸径が、柱状チタン酸アルミニウムの短軸径よりも大きい比較例８においては、柱状チタン酸アルミニウムの配向が、粒状チタン酸アルミニウムにより妨げられるため、柱状チタン酸アルミニウム粒子同士の重なりが減少する。このため、強度が低くなっている。また、焼結性が悪いため、押出方向と垂直な方向における熱膨張係数が高くなっている。 In Comparative Example 8 in which the major axis diameter of the granular aluminum titanate is larger than the minor axis diameter of the columnar aluminum titanate, the orientation of the columnar aluminum titanate is hindered by the granular aluminum titanate. The overlap of is reduced. For this reason, the strength is low. Moreover, since the sinterability is poor, the coefficient of thermal expansion in the direction perpendicular to the extrusion direction is high.
　以上のように、本発明に従い、柱状チタン酸アルミニウム：粒状チタン酸アルミニウムの重量比で、９５：５～６０：４０の範囲内の割合となるように、柱状チタン酸アルミニウムと粒状チタン酸アルミニウムを混合して用い、かつ粒状チタン酸アルミニウムの個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径よりも小さくなるように設定することにより、低い熱膨張係数を有し、気孔率が高く、かつ高強度で、耐熱衝撃性に優れたハニカムフィルタを得ることができる。 As described above, according to the present invention, columnar aluminum titanate and granular aluminum titanate are mixed so that the weight ratio of columnar aluminum titanate: particulate aluminum titanate is within the range of 95: 5 to 60:40. By mixing and setting the number average major axis diameter of the granular aluminum titanate to be smaller than the number average minor axis diameter of the columnar aluminum titanate, it has a low thermal expansion coefficient and has a porosity of A honeycomb filter having high and high strength and excellent thermal shock resistance can be obtained.
　１…ハニカム焼結体（ハニカムフィルタ）
　１ａ…ハニカム焼結体の端面
　２…ハニカム焼結体の中心部
　３…ハニカム焼結体から切り出した測定サンプル
　４…ハニカム焼結体の端面近傍の領域
　５…ハニカム焼結体の押出面をＸ線回折測定するためのサンプル
　５ａ…押出面 1 ... Honeycomb sintered body (honeycomb filter)
DESCRIPTION OF SYMBOLS 1a ... End face of honeycomb sintered body 2 ... Center part of honeycomb sintered body 3 ... Measurement sample cut out from honeycomb sintered body 4 ... Region in the vicinity of end face of honeycomb sintered body 5 ... Extruded surface of honeycomb sintered body X Sample 5a ... extruded surface for measuring line diffraction

Claims (2)

  1. 　チタン酸アルミニウムからなるハニカムフィルタであって、
    　アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３以上である柱状チタン酸アルミニウムと、アスペクト比（＝個数平均長軸径／個数平均短軸径）が１．３未満である粒状チタン酸アルミニウムとを、柱状チタン酸アルミニウム：粒状チタン酸アルミニウムの重量比で、９５：５～６０：４０の範囲内の割合となるように混合して用い、
    　粒状チタン酸アルミニウムの個数平均長軸径が、柱状チタン酸アルミニウムの個数平均短軸径よりも小さいことを特徴とするハニカムフィルタ。     A honeycomb filter made of aluminum titanate,
    Columnar aluminum titanate having an aspect ratio (= number average major axis diameter / number average minor axis diameter) of 1.3 or more and an aspect ratio (= number average major axis diameter / number average minor axis diameter) of less than 1.3 The granular aluminum titanate is mixed and used at a weight ratio of columnar aluminum titanate: particulate aluminum titanate within a range of 95: 5 to 60:40,
    A honeycomb filter, wherein the number average major axis diameter of granular aluminum titanate is smaller than the number average minor axis diameter of columnar aluminum titanate.
  2. 　押出成形により成形された成形体を焼成することによって得られるハニカムフィルタであり、押出方向に対して垂直な方向における３０～８００℃の間の熱膨張係数が、２．０×１０－６／℃以下であることを特徴とする請求項１に記載のハニカムフィルタ。 A honeycomb filter obtained by firing a molded body formed by extrusion, and has a thermal expansion coefficient of 2.0 × 10 −6 / ° C. between 30 and 800 ° C. in a direction perpendicular to the extrusion direction. The honeycomb filter according to claim 1, wherein:
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