JP2011245396A - Method for producing honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a honeycomb structure, easier than before, and allowing suppression of detachment of a sealing material from through holes.SOLUTION: This method for producing the honeycomb structure includes processes of: installing masks 200a each having a plurality of mask parts 270b and a plurality of opening parts 270a on an end face wherein the plurality of through holes 70a of a columnar body 70 formed with the through holes 70a are open, and closing a part of the through holes 70a by the mask parts 270b; applying the slurry-like sealing material 304 to the masks 200a installed on the end face; and pressing a blade 300 against the sealing material 304 applied to the masks 200a, and moving the blade 300 nearly parallel to the surfaces of the masks 200a.

Description

  The present invention relates to a method for manufacturing a honeycomb structure.

  Conventionally, a honeycomb structure made of porous ceramics has been used as a ceramic filter (DPF: Diesel Particulate Filter) for collecting fine particles such as carbon particles contained in exhaust gas discharged from an internal combustion engine such as a diesel engine. It has been.

  A honeycomb structure for a DPF is usually a columnar body, and the columnar honeycomb structure is formed with a plurality of through holes penetrating between the opposing end faces. On one end surface (first end surface) of the honeycomb structure, the end portions of the open through holes and the end portions of the through holes closed by the sealing portions are alternately arranged in a lattice pattern. The through hole whose end is open on the first end surface is closed with a sealing portion on the second end surface opposite to the first end surface. Further, the through hole whose end is closed by the sealing portion on the first end surface is open on the second end surface. Therefore, in manufacturing a honeycomb structure for DPF, a step of closing only one end portion of the through hole formed in the columnar body with a sealing material (hereinafter referred to as “sealing step”) is required.

  In Patent Document 1 below, as an example of the above-described sealing step, a cordierite columnar body in which a plurality of through-holes are formed is installed in a cylinder, and a part of the through-holes opened on the end surface of the columnar body is formed with a film. A process is disclosed in which a sealing material in the form of a slurry is applied to the end face, and the piston is pushed into the cylinder to introduce the sealing material into some through holes with the piston.

Japanese Patent Publication No. 63-24731

  However, the sealing process disclosed in Patent Document 1 is complicated because it requires a complicated device including a needle jig for making a hole in a film, a sealing piston, a cylinder, and the like. Further, in the sealing step disclosed in Patent Document 1, when the sealing material is introduced into the through hole by the piston, the piston and the end surface of the columnar body are in close contact with each other via the sealing material. Therefore, the sealing material introduced into the through hole by the piston is pulled out from the through hole as the piston is pulled out from the cylinder. Therefore, in the DPF manufactured using the sealing step disclosed in Patent Document 1, the fine particles pass through the through holes whose both ends are not blocked by the sealing portions, and the collection rate of the fine particles is high. It will decline.

  The present invention has been made in view of such problems of the prior art, and provides a method for manufacturing a honeycomb structure that is simpler than the prior art and can suppress the detachment of the sealing material from the through holes. With the goal.

  In order to achieve the above object, a method for manufacturing a honeycomb structure according to the present invention includes a mask having a plurality of mask portions and openings on an end face of a columnar body in which a plurality of through holes are formed. A step of closing a part of the through-holes in the mask portion, a step of applying a slurry-like sealing material to the mask installed on the end surface, and pressing the blade against the sealing material applied to the mask, Moving the substrate substantially parallel to the surface of the mask.

  In the above-described present invention, the blade is pressed against the sealing material applied to the mask, and the blade is moved substantially parallel to the surface of the mask, so that the sealing material fills the end of some through holes through the opening of the mask. Is done. That is, in the present invention, the sealing material is pushed into the end portions of some through holes by the blade. As described above, according to the present invention, if there is at least a blade and a mask, the end portion of the through hole can be filled with the sealing material, and the sealing process is simplified as compared with the conventional manufacturing method requiring a complicated apparatus system. .

  In the sealing step shown in Patent Document 1, as described above, the piston is pressed perpendicularly to the end surface of the columnar body, the sealing material is introduced into the through hole extending perpendicularly to the end surface, and then the piston is perpendicular to the end surface of the columnar body. To separate from the columnar body. And the sealing material in a through-hole may detach | leave from a through-hole with the vertical movement of this piston. This is because if the long axis direction of the through hole coincides with the moving direction of the piston, the sealing material is easily pulled out from the through hole as the piston moves. However, in the present invention, since the blade is moved in a direction parallel to the end surface of the columnar body (that is, a direction perpendicular to the long axis of the through hole), the sealing material is detached from the through hole as the blade moves. Not likely to occur.

  In the present invention described above, the columnar body is fitted into the bottom hole of the frame having the bottom plate in which the bottom hole having substantially the same shape as the end surface of the columnar body is formed. It is preferable to press the blade against the sealing material and move the blade substantially parallel to the surface of the mask. By using the frame, it is possible to prevent extra sealing material that is not introduced into the through-holes from being applied to the mask from adhering to the side surface of the columnar body. Further, by using the frame, it is possible to collect excess sealing material in the frame and reuse it in the sealing step. That is, in the present invention, the manufacturing cost of the honeycomb structure can be reduced by reusing the sealing material.

  In the said invention, it is preferable that a columnar body contains Al and Ti. A honeycomb structure formed from a columnar body containing Al and Ti is made of an aluminum titanate sintered body, has an extremely small thermal expansion coefficient, a high melting point, excellent thermal shock resistance during regeneration, and a limit deposition amount of soot. Is suitable as a large DPF.

  According to the present invention, it is possible to provide a method for manufacturing a honeycomb structure that is simpler than before and can suppress the detachment of the sealing material from the through holes.

Fig.1 (a) is a perspective view of the columnar body formed in the manufacturing process of the honeycomb structure which concerns on one Embodiment of this invention, FIG.1 (b) is an end surface of the columnar body of Fig.1 (a). FIG. 2A is a perspective view of the columnar body of FIG. 1A and a mask installed on an end surface of the columnar body, and FIG. 2B is a top view of the mask shown in FIG. 2A. It is. FIG. 3 is a perspective view of a columnar body in which a blade, a frame, and masks are installed on both end faces used in the sealing step in the method for manufacturing a honeycomb structure according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing a part of the sealing step corresponding to the IV-IV line cross section of the columnar body in which the blade, the frame, and the masks on both end faces shown in FIG. 3 are installed. FIG. 5 is a schematic diagram showing a part of the sealing step corresponding to the IV-IV line cross section of the columnar body in which the blade, the frame, and the masks on both end faces shown in FIG. 3 are installed. FIG. 6 is a schematic diagram showing a part of the sealing process corresponding to the IV-IV line cross section of the columnar body in which the blade, the frame, and the masks on both end faces shown in FIG. 3 are installed. FIG. 7A is a perspective view of a honeycomb structure manufactured by the method for manufacturing a honeycomb structure according to one embodiment of the present invention, and FIG. 7B is a view of the honeycomb structure of FIG. It is an end view.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, the same code | symbol is attached | subjected about the same or equivalent element. In addition, although the positional relationship between the top, bottom, left and right is as shown in the drawing, the ratio of dimensions is not limited to that shown in the drawing. First, the sealing step for the columnar body will be described, and then the other steps will be described.

(Columnar)
As shown in FIGS. 1A and 1B, the columnar body 70 is a cylindrical body having a honeycomb structure. The columnar body 70 has a plurality of partition walls 70c that are parallel to the central axis thereof and orthogonal to each other. That is, the columnar body 70 has a lattice structure in a cross section perpendicular to the central axis direction. In other words, the columnar body 70 is formed with a large number of through holes 70a (flow passages) extending in the same direction (center axis direction), and the partition walls 70c separate the through holes 70a. Each through hole 70 a is perpendicular to both end faces of the columnar body 70. In addition, the angle which the some partition 70c which the columnar body 70 has mutually is not specifically limited, For example, 120 degrees may be sufficient. The columnar body 70 may be a porous ceramic made of, for example, an aluminum titanate sintered body. In the present embodiment, “aluminum titanate sintered body” implies “aluminum magnesium titanate sintered body”. That is, the aluminum titanate sintered body may contain magnesium. Moreover, the aluminum titanate sintered body may contain silicon. In addition to the crystal pattern of aluminum titanate (Al ₂ TiO ₅ ) or aluminum magnesium titanate (Al _{2 (1-x)} Mg _x Ti _{(1 + x)} O ₅ ), the sintered aluminum titanate has an X-ray diffraction spectrum. Crystal patterns such as alumina and titania may be included. A method for forming the columnar body 70 will be described later. The columnar body 70 may be a green molded body (unfired molded body) formed from an inorganic compound powder (Al ₂ O ₃ , TiO _2, etc.) as a ceramic raw material and an organic binder. Below, the manufacturing method of the porous honeycomb structure which consists of an aluminum titanate sintered compact is demonstrated.

[Sealing process]
As shown in FIGS. 1 and 2, in the sealing step, the first mask 200 a is attached to the first end surface of the columnar body 70 where the plurality of through holes 70 a are open. In the first mask 200a, as shown in FIG. 2B, a plurality of mask portions 270a and openings 270b having substantially the same dimensions as the through holes 70a are arranged in a staggered manner. The first mask 200a is affixed to the first end surface of the columnar body 70 so that each through-hole 70a overlaps each mask portion 270a and the opening 270b. Further, the second mask 200b is attached to the second end surface of the columnar body 70 opposite to the first end surface. The arrangement relationship between the opening and the mask portion of the second mask 200b is opposite to that of the first mask 200a. Therefore, the through hole 70a closed by the mask portion 270b of the first mask 200a on the first end face side overlaps with the opening of the second mask 200b on the second end face side. The through hole 70a closed by the mask portion of the second mask 200b on the second end surface side overlaps the opening 270a of the first mask 200a on the first end surface side. Therefore, all of the plurality of through holes 70a formed in the columnar body 70 are opened at one of the first end surface and the second end surface, and are closed by the mask portion at the other. In addition, instead of using the first mask 200a, a (transparent) resin film in which no opening is formed is attached to the first end surface (through hole 70a) of the columnar body 70, and a heated metal rod or laser beam or the like. A plurality of openings 270a arranged in a checkered pattern may be formed in the film by the heat rays.

  As shown in FIG. 3, in the sealing step, a blade 300 (a spatula) and a rectangular frame 302 are used. The frame 302 includes a bottom plate 302a. In the bottom plate 302a, a circular bottom hole 302b having a shape substantially the same as that of the first end surface of the columnar body 70 is formed. The columnar body 70 to which the first mask 200 a and the second mask 200 b are attached is fitted into the bottom hole 302 b of the frame 302. As a result, the first end surface to which the first mask 200 a is attached is surrounded by the frame 302. The shape of the frame 302 is not particularly limited. The frame 302 may be fixed to the columnar body 70 using an adhesive tape or a jig.

  A slurry-like sealing material 304 is applied to the entire surface of the first mask 200a disposed in the frame 302 with a substantially uniform thickness. As the sealing material 304, a mixture of an inorganic compound powder (ceramic material, ceramic raw material powder or a mixture thereof), an organic binder, a lubricant, a pore forming agent, a solvent, and the like may be used. The composition of the inorganic compound powder contained in the sealing material 304 may be the same as or different from the composition of the inorganic compound powder for forming the columnar body 70. For example, the entire columnar body 70 fitted in the frame 302 may be installed in a vibrator, and the sealing material 304 applied to the first mask 200a may be vibrated. By this vibration, the sealing material 304 on the first mask 200a is flattened, and the bubbles in the sealing material 304 are removed.

  As shown in FIGS. 4 to 6, the blade 300 is moved in parallel with the surface of the first mask 200 a while pressing the tip of the blade 300 against the sealing material 304 applied to the entire surface of the first mask 200 a, and the blade 300 is moved. Then, the entire surface of the first mask 200a is scanned. As a result, as shown in FIGS. 5 and 6, the sealing material 304 is introduced substantially uniformly through the opening into the end of each through hole 70 a that overlaps the opening of the first mask 200 a. At this time, the sealing material 304 remaining without being introduced into the end portion of the through hole 70 a is collected in the frame 302. That is, the frame 302 functions as a tray for the extra sealing material 304. In the sealing step, after the sealing material 304 is introduced into the through hole 70a, the entire columnar body 70 may be vibrated by a vibrator. As a result, the sealing material 304 is easily filled in the gaps at the ends of the through holes 70a.

  After the sealing step for the first end surface, the columnar body 70 is removed from the bottom hole 302b of the frame 302. Next, similarly to the above-described sealing step for the first end surface, the sealing step for the second end surface to which the second mask 200b is attached is performed. After performing the sealing step on both end faces, each mask is peeled off from each end face. In addition, instead of using the second mask 200b, a (transparent) resin film in which no opening is formed is attached to the second end surface (through hole 70a) of the columnar body 70, a heated metal rod, a laser beam, or the like A plurality of openings arranged in a checkered pattern may be formed in the film by the heat rays.

  After performing the above-described sealing step for the first end surface and the second end surface, the dried columnar body is fired to seal the sealing material 304 that closes one end of the through hole 70a. By sintering the sealing material 304, as shown in FIG. 7, a ceramic sealing portion 70 b that closes one end of the through hole 70 a is formed, and the cylindrical honeycomb structure 170 is completed.

(Honeycomb structure)
In the honeycomb structure 170, the through hole 70a closed by the sealing portion 70b on the first end face side is open on the second end face side. The through hole 70a closed by the sealing portion 70b on the second end surface side is open on the first end surface side. A honeycomb structure (multi-cell ceramic monolith) having such a structure is suitable for DPF. In particular, DPF made of sintered aluminum magnesium titanate has an extremely small coefficient of thermal expansion, a high melting point, and excellent thermal shock resistance during reproduction, compared with DPF made of SiC, cordierite or aluminum titanate alone. It is excellent in that the limit deposition amount of is large. Note that a platinum-based metal catalyst supported on a carrier such as alumina or a promoter such as ceria or zirconia may be attached to the partition wall surface of the honeycomb structure 170 for DPF.

  Although the aluminum content rate in an aluminum titanate sintered compact is not specifically limited, For example, it is 40-60 mol% in conversion of aluminum oxide. Although the content rate of titanium in an aluminum titanate sintered compact is not specifically limited, For example, it is 35-55 mol% in titanium oxide conversion. The magnesium content in the aluminum titanate sintered body is preferably 1 to 5% by mass in terms of magnesium oxide. The silicon content in the aluminum titanate sintered body is preferably 2 to 5% by mass in terms of silicon oxide. In addition, what is necessary is just to adjust suitably the composition of an aluminum titanate sintered compact with the composition of a raw material mixture. In addition to the above components, the aluminum titanate sintered body may contain components derived from raw materials or trace components inevitably mixed into work-in-process in the manufacturing process.

The inner diameter (the length of one side of the square) of the cross section perpendicular to the longitudinal direction of the through hole 70a is not particularly limited, and is, for example, 0.8 to 2.5 mm. The length of the honeycomb structure 170 in the direction in which the through hole 70a extends is not particularly limited, and is, for example, 40 to 350 mm. Further, the outer diameter of the honeycomb structure 170 is not particularly limited, but is, for example, 10 to 320 mm. Although the length D of the sealing part 70b is not specifically limited, For example, it is 1-20 mm. The number (cell density) of the through holes 70a opened in the end face of the honeycomb structure 170 is not particularly limited, and is, for example, 150 to 450 cpsi. The unit of cpsi means “/ inch ² ” and is equal to “/(0.0254m) ² ”. Although the thickness of the partition of the through-hole 70a is not specifically limited, For example, it is 0.15-0.76 mm.

[Method of forming columnar body]
(Preparation of raw material mixture)
In order to form a columnar body, a raw material mixture prepared by mixing an inorganic compound powder, an organic binder, a solvent, and the like with a kneader or the like is molded to obtain a green molded body. The inorganic compound powder includes a titanium source powder and an aluminum source powder. The inorganic compound powder may further contain a magnesium source powder and a silicon source powder.

(Aluminum source)
The aluminum source is a compound that becomes an aluminum component constituting the aluminum titanate sintered body. Examples of the aluminum source include alumina (aluminum oxide). Examples of the crystal type of alumina include γ-type, δ-type, θ-type, and α-type, and may be indefinite (amorphous). Of these, α-type alumina is preferably used.

  The aluminum source may be a compound that is led to alumina by firing alone in air. Examples of such a compound include an aluminum salt, aluminum alkoxide, aluminum hydroxide, and metal aluminum.

  The aluminum salt may be an inorganic salt with an inorganic acid or an organic salt with an organic acid. Specific examples of the aluminum inorganic salt include aluminum nitrates such as aluminum nitrate and ammonium aluminum nitrate, and aluminum carbonates such as ammonium aluminum carbonate. Examples of the aluminum organic salt include aluminum oxalate, aluminum acetate, aluminum stearate, aluminum lactate, and aluminum laurate.

  Specific examples of the aluminum alkoxide include aluminum isopropoxide, aluminum ethoxide, aluminum sec-butoxide, aluminum tert-butoxide, and the like.

  Examples of the crystal type of aluminum hydroxide include gibbsite type, bayerite type, norosotrandite type, boehmite type, and pseudoboehmite type, and may be amorphous (amorphous). Examples of the amorphous aluminum hydroxide include an aluminum hydrolyzate obtained by hydrolyzing an aqueous solution of a water-soluble aluminum compound such as an aluminum salt or an aluminum alkoxide.

  As an aluminum source, only 1 type may be used and 2 or more types may be used together.

  Of the above, alumina is preferably used as the aluminum source, and more preferably α-type alumina. The aluminum source may contain trace components derived from the raw materials or inevitably contained in the production process.

  The particle size of the aluminum source powder is not particularly limited. For example, the particle diameter of the aluminum source powder corresponding to a volume-based cumulative percentage of 50% measured by a laser diffraction method may be in the range of 20 to 60 μm. This particle diameter is also called D50 or average particle diameter. From the viewpoint of reducing shrinkage during firing, it is preferable to use an aluminum source powder having a D50 in the range of 30 to 60 μm.

  An alumina sol or a silica sol described later can be added to the raw material mixture. Thus, by adding alumina sol, silica sol, etc., fine particles in the raw material mixture are adsorbed to each other, and the amount of particles having a particle diameter of 0.1 μm or less in the green molded body is reduced to an inorganic compound powder (solid content). From 1 to 5 parts by weight per 100 parts by weight, the strength of the compact after degreasing at 500 ° C. can be, for example, 0.2 kgf or more.

  The alumina sol is a colloid using fine particle alumina as a dispersoid and a liquid as a dispersion medium. Alumina sol can be used alone as an aluminum source, but is preferably used in combination with other aluminum sources. The dispersion medium of alumina sol is removed by evaporation or the like at the time of mixing or calcination, for example.

Examples of the dispersion medium for the alumina sol include aqueous solutions and various organic solvents such as aqueous hydrochloric acid, aqueous acetic acid, aqueous nitric acid, alcohol, xylene, toluene, and methyl isobutyl ketone. As the alumina sol, a colloidal alumina sol having an average particle diameter of 1 to 100 nm is preferably used. By using an alumina sol having such an average particle size, there is an advantage that particles in the raw material mixture can be adsorbed. Examples of commercially available products of alumina sol include “Alumina sol 100”, “Alumina sol 200”, “Alumina sol 520” manufactured by Nissan Chemical Industries, Ltd., “NanoTekAl ₂ O ₃ ” manufactured by CI Kasei. Among these, it is preferable to use "Alumina sol 200" manufactured by Nissan Chemical Industries.

  The alumina sol can be used in an amount of 0 to 10 parts by weight, preferably 0 to 5 parts by weight, based on 100 parts by weight of the inorganic compound powder (solid content). Two or more kinds of alumina sols may be mixed and used.

(Titanium source)
The titanium source is a compound that becomes a titanium component constituting the aluminum titanate sintered body, and examples of such a compound include titanium oxide. Examples of titanium oxide include titanium (IV) oxide, titanium (III) oxide, and titanium (II) oxide. Among these, titanium (IV) oxide is preferably used. Examples of the crystal form of titanium (IV) oxide include anatase type, rutile type, brookite type and the like, and may be indefinite (amorphous). More preferred is anatase type or rutile type titanium (IV) oxide.

  The titanium source may be a compound that is led to titania (titanium oxide) by firing alone in air. Examples of such compounds include titanium salts, titanium alkoxides, titanium hydroxide, titanium nitride, titanium sulfide, titanium metal and the like.

  Specific examples of the titanium salt include titanium trichloride, titanium tetrachloride, titanium sulfide (IV), titanium sulfide (VI), titanium sulfate (IV), and the like. Specific examples of titanium alkoxide include titanium (IV) ethoxide, titanium (IV) methoxide, titanium (IV) t-butoxide, titanium (IV) isobutoxide, titanium (IV) n-propoxide, titanium (IV) tetraiso Examples thereof include propoxide and chelates thereof.

  As a titanium source, only 1 type may be used and 2 or more types may be used together.

  Among the above, as the titanium source, titanium oxide is preferably used, and titanium (IV) oxide is more preferable. In addition, a titanium source can contain the trace component contained unavoidable in the raw material origin or manufacturing process.

  The particle size of the titanium source powder is not particularly limited. For example, the particle diameter (D50) of the titanium source powder corresponding to a volume-based cumulative percentage of 50% as measured by a laser diffraction method may be in the range of 0.5 to 25 μm. In order to achieve a sufficiently low firing shrinkage ratio, the D50 of the titanium source powder is preferably in the range of 1 to 20 μm. The titanium source powder may show a bimodal particle size distribution. When using a titanium source powder showing such a bimodal particle size distribution, the particle size distribution measured by the laser diffraction method is used. It is preferable that the particle diameter of the peak with a larger particle diameter is in the range of 20 to 50 μm.

  The mode diameter of the titanium source powder measured by the laser diffraction method is not particularly limited as long as it is in the range of 0.3 to 60 μm.

(Magnesium source)
The raw material mixture may contain a magnesium source. An aluminum titanate sintered body produced from a green molded body containing a magnesium source is a sintered body of aluminum magnesium titanate crystals.

  Examples of the magnesium source include magnesia (magnesium oxide) and a compound that is led to magnesia by firing alone in air. Examples of the latter include magnesium salt, magnesium alkoxide, magnesium hydroxide, magnesium nitride, metal magnesium and the like.

  Specific examples of magnesium salts include magnesium chloride, magnesium perchlorate, magnesium phosphate, magnesium pyrophosphate, magnesium oxalate, magnesium nitrate, magnesium carbonate, magnesium acetate, magnesium sulfate, magnesium citrate, magnesium lactate, magnesium stearate, Examples include magnesium salicylate, magnesium myristate, magnesium gluconate, magnesium dimethacrylate, and magnesium benzoate.

  Specific examples of the magnesium alkoxide include magnesium methoxide and magnesium ethoxide. In addition, a magnesium source can contain the trace component contained unavoidable in the raw material origin or manufacturing process.

As the magnesium source, a compound serving both as a magnesium source and an aluminum source can also be used. An example of such a compound is magnesia spinel (MgAl ₂ O ₄ ).

  As a magnesium source, only 1 type may be used and 2 or more types may be used together.

  The particle size of the magnesium source powder is not particularly limited. For example, the particle diameter (D50) of the magnesium source powder corresponding to a volume-based cumulative percentage of 50% measured by a laser diffraction method may be in the range of 0.5 to 30 μm. From the viewpoint of reducing shrinkage during firing, it is preferable to use a magnesium source powder having a D50 in the range of 3 to 20 μm.

The molar amount of the magnesium source in terms of MgO (magnesia) in the green molded body is based on the total molar amount of the aluminum source in terms of Al ₂ O ₃ (alumina) and the titanium source in terms of TiO ₂ (titania). 0.03 to 0.15, and more preferably 0.03 to 0.12. By adjusting the content of the magnesium source within this range, an aluminum titanate sintered body having a large pore diameter and an open porosity with improved heat resistance can be obtained relatively easily.

(Silicon source)
The raw material mixture may further contain a silicon source. The silicon source is a compound that becomes a silicon component and is contained in the aluminum titanate sintered body. By using the silicon source in combination, it becomes possible to obtain an aluminum titanate sintered body with improved heat resistance. Examples of the silicon source include silicon oxides (silica) such as silicon dioxide and silicon monoxide.

  The silicon source may be a compound that is led to silica by firing alone in air. Examples of such compounds include silicic acid, silicon carbide, silicon nitride, silicon sulfide, silicon tetrachloride, silicon acetate, sodium silicate, sodium orthosilicate, feldspar, and glass frit. Among them, feldspar, glass frit and the like are preferably used, and glass frit and the like are more preferably used in terms of industrial availability and stable composition. Glass frit means flakes or powdery glass obtained by pulverizing glass. As the silicon source, a powder made of a mixture of feldspar and glass frit can also be used.

  When the silicon source is a glass frit, it is preferable to use one having a yield point of 700 ° C. or higher from the viewpoint of further improving the thermal decomposition resistance of the obtained aluminum titanate sintered body. The yield point of the glass frit is defined as a temperature (° C.) at which the expansion of the glass frit is measured from a low temperature by using a thermo mechanical analyzer (TMA), and the expansion stops and then the contraction starts.

As the glass constituting the glass frit, a general silicate glass containing silicate (SiO ₂ ) as a main component (50% by weight or more in all components) can be used. The glass constituting the glass frit includes other components such as alumina (Al ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), calcium oxide ( CaO), magnesia (MgO) and the like may be included. The glass constituting the glass frit may contain ZrO ₂ in order to improve the hot water resistance of the glass itself.

  As a silicon source, only 1 type may be used and 2 or more types may be used together.

  The particle size of the silicon source powder is not particularly limited. For example, the particle diameter (D50) of the silicon source corresponding to a volume-based cumulative percentage of 50% measured by laser diffraction method may be in the range of 0.5 to 30 μm. In order to further improve the specific gravity of the green molded body and obtain a fired body having higher mechanical strength, it is preferable that D50 of the silicon source is in the range of 1 to 20 μm.

When the raw material mixture contains a silicon source, the content of the silicon source in the raw material mixture is 100 parts by weight of the total amount of the aluminum source in terms of Al ₂ O ₃ (alumina) and the titanium source in terms of TiO ₂ (titania). On the other hand, it is usually 0.1 to 10 parts by weight, preferably 5 parts by weight or less in terms of SiO ₂ (silica). Further, the content of the silicon source in the raw material mixture is more preferably 2% by weight or more and 5% by weight or less in the inorganic compound source contained in the raw material mixture. The silicon source may contain trace components that are derived from the raw materials or inevitably contained in the production process.

As a composite oxide such as magnesia spinel (MgAl ₂ O ₄ ), a compound containing two or more metal elements among titanium, aluminum, silicon, and magnesium can be used as a raw material.

  When the content of particles having a particle size of 0.1 μm or less in 100 parts by weight of the inorganic compound powder in the raw material mixture is 1 to 5 parts by weight, the alumina sol and / or silica sol is added to the raw material mixture and mixed as described above. It is preferable to do. Silica sol is a colloid using fine particle silica as a dispersoid and liquid as a dispersion medium. The silica sol can be used alone as a silicon source, but is preferably used in combination with other silica sources. The dispersion medium of silica nasol is removed by evaporation or the like at the time of mixing or calcination, for example.

  Examples of the dispersion medium for silica sol include aqueous solutions and various organic solvents such as an aqueous ammonia solution, alcohol, xylene, toluene, and triglyceride. As the silica sol, a colloidal silica sol having an average particle diameter of 1 to 100 nm is preferably used. By using a silica sol having such an average particle size, there is an advantage that particles in the raw material mixture can be adsorbed and melted and bonded during firing.

  Examples of commercially available silica sols include “Snowtex 20, 30, 40, 50, N, O, S, C, 20L, OL, XS, XL, YL, ZL, QAS-40, LSS manufactured by Nissan Chemical Industries, Ltd. -35, LSS-45 "," Adelite AT-20, AT-30, AT-40, AT-50, AT-20N, AT-20A, AT-30A, AT-20Q, AT-300, manufactured by Asahi Denka Co., Ltd. "AT-300Q", "Cataloid S-20L, S-20H, S-30L, S-30H, SI-30, SI-40, SI-50, SI-350, SI-500, SI-" manufactured by Catalyst Kasei Kogyo Co., Ltd. 45P, SI-80P, SN, SA, SC-30 "," Ludox HS-40, HS-30, LS, SM-30, TM, AS, AM "manufactured by DuPont. Among these, it is preferable to use “Snowtex C” that is stable in a colloidal state in a neutral region.

  Content of the silica sol in a raw material mixture should just be 0-10 weight part by solid content with respect to 100 weight part of inorganic compound powder (solid content), Preferably it may be 0-5 weight part. Two or more kinds of silica sols may be mixed and used.

  The raw material mixture may contain aluminum titanate or aluminum magnesium titanate. For example, when aluminum magnesium titanate is used as a constituent of the raw material mixture, the aluminum magnesium titanate corresponds to a raw material having both a titanium source, an aluminum source, and a magnesium source.

(Organic binder)
As the organic binder, a water-soluble organic binder is preferable. Examples of the water-soluble organic binder include celluloses such as methylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose; alcohols such as polyvinyl alcohol; salts such as lignin sulfonate.

  The amount of the organic binder is usually 20 parts by weight or less, preferably 15 parts by weight or less, and more preferably 6 parts by weight with respect to 100 parts by weight of the inorganic compound powder. The lower limit amount of the organic binder is usually 0.1 parts by weight, preferably 3 parts by weight.

(solvent)
As the solvent, for example, alcohols such as methanol, ethanol, butanol and propanol, glycols such as propylene glycol, polypropylene glycol and ethylene glycol, and polar solvents such as water can be used. Of these, water is preferable, and ion-exchanged water is more preferably used from the viewpoint of few impurities. The amount of the solvent used is usually 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the inorganic compound powder. A nonpolar solvent may be used as the solvent.

(Other additives)
The raw material mixture can contain an organic additive other than the organic binder. Other organic additives are, for example, pore formers, lubricants and plasticizers, and dispersants.

  Examples of the pore-forming agent include carbon materials such as graphite, resins such as polyethylene, polypropylene, and polymethyl methacrylate, plant materials such as starch, nut shells, walnut shells, and corn, ice, and dry ice. The addition amount of the pore-forming agent is usually 0 to 40 parts by weight, preferably 0 to 25 parts by weight with respect to 100 parts by weight of the inorganic compound powder. The pore former disappears when the green molded body is fired. Therefore, in the aluminum titanate sintered body, micropores are formed at locations where the pore-forming agent was present. The pore size of the fine pores is smaller than the particle size of fine particles derived from diesel fuel. Therefore, the gas can pass through the fine pores, but the fine particles cannot pass.

  Examples of the lubricant and plasticizer include alcohols such as glycerin, caprylic acid, lauric acid, palmitic acid, higher fatty acids such as alginate, oleic acid and stearic acid, and stearic acid metal salts such as Al stearate. The addition amount of the lubricant and the plasticizer is usually 0 to 10 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the inorganic compound powder.

  Examples of the dispersant include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid, organic acids such as oxalic acid, citric acid, acetic acid, malic acid and lactic acid, alcohols such as methanol, ethanol and propanol, ammonium polycarboxylate, Surfactants such as oxyalkylene alkyl ethers are listed. The addition amount of the dispersing agent is usually 0 to 20 parts by weight, preferably 2 to 8 parts by weight with respect to 100 parts by weight of the inorganic compound powder.

(Formation of green molded body)
A green molded body is formed by molding the above-described raw material mixture using an extruder having a die having a lattice-shaped opening. In addition, you may knead | mix the raw material mixture before shaping | molding.

(Calcination and firing of green molded body)
A columnar body can be obtained by calcining (degreasing) and firing the green molded body described above. The obtained columnar body is mainly composed of a sintered body of crystal grains of aluminum titanate. In this embodiment, by performing firing after forming the raw material mixture, it is possible to suppress shrinkage during firing compared to the case of directly firing the raw material mixture, and cracking of the obtained aluminum titanate sintered body In addition, it is possible to obtain an aluminum titanate sintered body in which the pore shape of the porous aluminum titanate crystal generated by firing is maintained. As described above, the green molded body may be used as a columnar body without firing.

  Calcination (degreasing) is a process for removing the organic binder in the green molded body and the organic additive blended as necessary by burning, decomposition, or the like. A typical calcination process corresponds to an initial stage of the firing process, that is, a temperature raising stage (for example, a temperature range of 300 to 900 ° C.) until the green molded body reaches the firing temperature. In the calcination (degreasing) step, it is preferable to suppress the temperature increase rate as much as possible.

  The firing temperature of the green molded body is usually 1300 ° C. or higher, preferably 1400 ° C. or higher. The firing temperature is usually 1650 ° C. or lower, preferably 1550 ° C. or lower. By heating the green molded body within this temperature range, the inorganic compound powder in the green molded body is surely sintered. The rate of temperature increase up to the firing temperature is not particularly limited, but is usually 1 ° C./hour to 500 ° C./hour.

  Firing is usually performed in the atmosphere, but depending on the type and usage ratio of the raw material powder used, that is, aluminum source powder, titanium source powder, magnesium source powder and silicon source powder, an inert gas such as nitrogen gas or argon gas. The firing may be performed in a reducing gas such as carbon monoxide gas or hydrogen gas. Further, the firing may be performed in an atmosphere in which the water vapor partial pressure is lowered.

  Firing is usually performed using a conventional firing furnace such as a tubular electric furnace, a box-type electric furnace, a tunnel furnace, a far-infrared furnace, a microwave heating furnace, a shaft furnace, a reflection furnace, a rotary furnace, or a roller hearth furnace. Firing may be performed batchwise or continuously. Moreover, you may carry out by a stationary type and may carry out by a fluid type.

  The time required for firing may be sufficient time for the green molded body to transition to the aluminum titanate crystal, and varies depending on the amount of the green molded body, the type of firing furnace, firing temperature, firing atmosphere, etc. 10 minutes to 24 hours.

  Note that the green molded body may be calcined and fired separately. In the calcining step, the green molded body may be heated at a temperature equal to or higher than the thermal decomposition temperature of the organic binder and other organic additives and lower than the sintering temperature of the inorganic compound powder. In the firing step, the green molded body after the calcining step may be heated at a temperature equal to or higher than the sintering temperature of the inorganic compound powder.

  As described above, the columnar body 70 having a honeycomb structure can be obtained. Such a columnar body 70 has a shape that substantially maintains the shape of the green molded body immediately after molding. The obtained columnar body 70 can be processed into a desired shape by grinding or the like.

  As mentioned above, although one suitable embodiment of the present invention was described in detail, the present invention is not limited to the above-mentioned embodiment.

  For example, even when the sealing step is performed without using the frame 302, the effects of the present invention can be achieved.

  The honeycomb structure 170 may be a porous ceramic made of cordierite or silicon carbide. In this case, the columnar body includes cordierite, silicon carbide, or raw material powder thereof. The shape of the honeycomb structure 170 is not limited to a cylinder, and can take any shape depending on the application. For example, the shape of the honeycomb structure 170 may be a polygonal column, an elliptical column, or the like.

  The use of the honeycomb structure is not limited to DPF. The honeycomb structure includes an exhaust gas filter or catalyst carrier used for exhaust gas purification of an internal combustion engine such as a gasoline engine, a filter used for filtering food and drink such as beer, and gas components (for example, carbon monoxide, carbon dioxide, etc.) generated during petroleum refining. , Nitrogen, oxygen, etc.) can be suitably applied to ceramic filters such as a selective permeation filter. Especially, when using as a ceramics filter etc., since an aluminum titanate sintered compact has a high pore volume and an open porosity, it can maintain favorable filter performance over a long period of time.

  70 ... columnar body, 70a ... through hole, 70b ... sealing part, 70c ... partition, 200a ... first mask, 200b ... second mask, 270a ... opening, 270b ... Mask portion, 300 ... Blade, 302 ... Frame, 302a ... Bottom plate, 302b ... Bottom hole, 304 ... Sealing material, 170 ... Honeycomb structure.

Claims (3)

A step of installing a mask having a plurality of mask portions and openings on an end face of the columnar body in which a plurality of through holes are formed, and closing the part of the through holes with the mask portion;
Applying a slurry-like sealing material to the mask placed on the end face;
Pressing a blade against the sealing material applied to the mask, and moving the blade substantially parallel to the surface of the mask;
A method for manufacturing a honeycomb structure. The columnar body was fitted into the bottom hole of a frame having a bottom plate in which a bottom hole having substantially the same shape as the end surface was formed, and the end surface on which the mask was installed was surrounded by the frame and applied to the mask A blade is pressed against the sealing material, and the blade is moved substantially parallel to the surface of the mask;
The method for manufacturing a honeycomb structured body according to claim 1. The columnar body includes Al and Ti;
The manufacturing method of the honeycomb structure according to claim 1 or 2.

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