JP2011245686A - Apparatus for manufacturing honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a honeycomb structure, capable of controlling the desorption of sealing materials from a through-hole.SOLUTION: The apparatus for manufacturing the honeycomb structure 170 includes: a base 300; a frame 302 mounted on the surface of the base 300; a mask 200a, which is disposed at an edge where a through-hole 70a of a column 70 with a plurality of through-holes 70a formed therein is opened, which has a plurality of mask sections 270b and openings 270a, and in which the mask sections 270b closes part of the through-holes 70a; a pressing unit 400 for pressing the edge of the column 70 with the disposed mask 200a to a slurry-like sealing material 304 supplied in the frame 302; and a movement unit 600 for moving the column 70 pressed to the sealing material 304 along with the frame 302 in the direction substantially parallel to the surface of the base 300.

Description

  The present invention relates to an apparatus 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

  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 the above-described problems of the prior art, and an object thereof is to provide an apparatus for manufacturing a honeycomb structure that can suppress the detachment of the sealing material from the through hole.

  In order to achieve the above object, a honeycomb structure manufacturing apparatus according to the present invention includes a pedestal, a frame placed on the surface of the pedestal, and through holes in a columnar body in which a plurality of through holes are formed. The end surface of the columnar body on which a mask having a plurality of mask portions and openings, having a plurality of mask portions and openings and blocking some through holes in the mask portion, and the columnar body on which the mask is disposed is provided in a frame. A pressing unit that presses against the sealing material; and a moving unit that moves the columnar body pressed against the sealing material together with the frame in a direction substantially parallel to the surface of the pedestal.

  In the present invention, the end face of the columnar body on which the mask is installed is pressed against the slurry-like sealing material so that the long axis direction of the through hole is perpendicular to the surface of the pedestal. Then, the sealing material is filled into the end portions of some through holes through the openings of the mask. Further, by this pressing, the end face of the columnar body and the surface of the pedestal are brought into close contact via the sealing material. After introducing the sealing material into the through hole, the columnar body is separated from the base by the moving means. If the columnar body is moved in a direction perpendicular to the surface of the pedestal to separate the columnar body from the pedestal, the sealing material in the through hole is detached from the through hole with the vertical movement of the columnar body. This is because if the long axis direction of the through hole coincides with the moving direction of the columnar body, the sealing material is easily pulled out from the through hole as the columnar body moves. However, in the present invention, the columnar body is separated from the pedestal by moving the columnar body together with the frame in a direction parallel to the surface of the pedestal (that is, a direction orthogonal to the long axis of the through hole). The accompanying sealing material is less likely to be detached from the through hole.

  In the present invention, the frame is preferably a rubber frame. Since the rubber-like frame easily adheres to the columnar body, when the end surface of the columnar body is pressed against the slurry-like sealing material supplied in the frame, the sealing material installed in the frame is not connected to the columnar body and the frame. It becomes difficult to leak from the outside to the outside of the frame, and the sealing material is easily introduced into the through hole of the columnar body.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing apparatus of the honeycomb structure which can suppress detachment | desorption of the sealing material from a through-hole.

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 an upper surface of the mask shown in FIG. 2A. FIG. Fig.3 (a) is a perspective view of the base material with which the manufacturing apparatus of the honeycomb structure which concerns on one Embodiment of this invention, a frame, and the sealing material supplied in the frame, FIG.3 (b) is FIG.3. It is the IIIb-IIIb sectional view taken on the line of the pedestal, the frame and the sealing material shown in (a). FIG. 4 is a schematic diagram showing a part of the sealing step for the columnar body using the honeycomb structure manufacturing apparatus according to the embodiment of the present invention. FIG. 5 is a schematic diagram showing a part of the sealing step for the columnar body using the honeycomb structure manufacturing apparatus according to the embodiment of the present invention. FIG. 6 is a schematic diagram showing a part of the sealing step for the columnar body using the honeycomb structure manufacturing apparatus according to the embodiment of the present invention. Fig.7 (a) is a perspective view of the honeycomb structure manufactured using the manufacturing apparatus of the honeycomb structure which concerns on one Embodiment of this invention, FIG.7 (b) is the honeycomb structure of Fig.7 (a). It is an end view of a body. FIG. 8 is a cross-sectional view taken along line VIII-VIII of the honeycomb structure shown in FIG. FIG. 9 is a cross-sectional view of a frame included in a honeycomb structure manufacturing apparatus according to another embodiment of the present invention.

  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.

<Outline of manufacturing apparatus for honeycomb structure>
As shown in FIGS. 2 to 6, the honeycomb structure manufacturing apparatus according to the present embodiment is installed on the pedestal 300, the ring-shaped frame 302 placed on the surface of the pedestal 300, and the end face of the columnar body 70. Masks 200 a and 200 b, a pressing unit 400 that presses the end face of the columnar body 70 on which the mask 200 a is installed against the slurry-like sealing material 304 supplied into the frame 302, and a columnar shape that is pressed against the sealing material 304. Moving means 600 for moving the body 70 together with the frame 302 in a direction parallel to the surface of the pedestal. The honeycomb structure manufacturing apparatus according to this embodiment is used in the sealing step for the columnar body 70. Below, the manufacturing method of the honeycomb structure using the manufacturing apparatus of the honeycomb structure which concerns on this embodiment is demonstrated. First, the sealing step for the columnar body will be described, and then the other steps will be described.

<Manufacturing method of honeycomb structure>
(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 or the like) as a raw material for ceramics, an organic binder, or the like. 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 FIGS. 3A and 3B, a ring-shaped frame 302 is placed on the flat surface of the pedestal 300, and a means for supplying a sealing material (not shown) is used to remove the frame 302. Slurry sealing material 304 is supplied inside. As the frame 302, it is preferable to use a rubber frame that is easily in close contact with the columnar body 70. In order to bring the frame 302 and the columnar body 70 into close contact with each other, the shape of the frame 302 and the shape of the first end surface of the columnar body 70 are preferably substantially the same. Note that the sealing material 304 supplied into the frame 302 may be vibrated by a vibrator. By this vibration, the sealing material 304 in the frame 302 is flattened, and bubbles in the sealing material 304 are removed. Further, it is preferable that the frame 302 is closely attached or fixed to the surface of the base 300 without a gap. Thereby, it is possible to prevent the sealing material 304 from leaking between the frame 302 and the pedestal 300. A method for closely attaching or fixing the frame 302 to the surface of the base 300 is not particularly limited. For example, a double-sided adhesive tape may be interposed between the frame 302 and the pedestal 300. A pedestal 300 having the same shape as the frame 302 may be used, and the frame 302 and the pedestal 300 may be overlapped and an adhesive tape may be wound around these outer peripheral surfaces. In the case of using an adhesive tape, the adhesive tape may be removed after the sealing member 304 is introduced into the through hole 70a and before the columnar body 70 and the frame 302 are moved by the moving means 600. Alternatively, the frame 302 may be provided with a magnet, and the frame 302 may be brought into close contact with the metal base 300 by magnetic force.

  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.

  As shown in FIGS. 4 and 5, the first end surface of the columnar body 70 to which the first mask 200 a is attached is pressed against the sealing material 304 in the frame 302. As a result, as shown in FIG. 5, the sealing material 304 is introduced substantially uniformly through the opening 270a into the end of each through hole that overlaps the opening 270a of the first mask 200a. It is preferable that the entire first end surface of the columnar body 70 is immersed in the sealing material 304 so that the first mask 200a attached to the first end surface is brought into contact with the surface of the base 300. Thereby, the sealing material 304 is more reliably filled in the end portion of the through hole 70a. 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 end portions of the through holes 70a.

  After the sealing material 304 is introduced into the through hole 70 a, the columnar body 70 pressed against the sealing material 304 is moved together with the frame 302 in a direction substantially parallel to the surface of the base 300 by the moving means 600. And the frame 302 is separated from the surface of the base 300. After separating the columnar body 70 from the surface of the base together with the frame 302, the frame 302 is removed from the columnar body 304.

  The sealing step for the second end surface to which the second mask 200b is attached is performed in the same manner as the above-described sealing step for the first end surface to which the first mask 200a is attached. 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 FIGS. 7 and 8, a ceramic sealing portion 70b for closing one end of the through hole 70a is formed, and a 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, 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 and a solvent 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, the honeycomb structure 170 may be a porous ceramic made of cordierite, silicon carbide, or the like. 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. Also, the shape of the frame 302 can be any shape that matches the shape of the honeycomb structure 170, and may be a polygon or an ellipse.

  As shown in FIG. 9, a tapered rubber ring 302a having an inner diameter substantially the same as the outer diameter of the end face of the columnar body may be used as the frame 302a. The tapered rubber ring 302a is placed on the surface of the pedestal 300 with the side with the largest inner diameter of the tapered rubber ring 302a facing away from the surface of the pedestal 300, and the sealing material 304 is attached to the tapered rubber ring 302a. You may supply. In this case, when the columnar body is pressed against the sealing material 304 in the tapered rubber ring 302a, the columnar body and the tapered rubber ring 302a are easily brought into close contact with each other, and the sealing material is interposed between the columnar body and the tapered rubber ring 302a. Since it becomes difficult to escape, the sealing material 304 is easily introduced into the through hole 70a in the vicinity of the peripheral edge of the end face of the columnar body.

  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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

Example 1
A raw material mixture containing an inorganic compound powder, an organic binder, a lubricant, a pore former, a plasticizer, a dispersant, and water (solvent), which are raw materials for the aluminum titanate crystal, was prepared. This raw material mixture was kneaded and extruded to produce a green molded body (columnar body 70) having a honeycomb structure as shown in FIG. The inner diameter (the length of one side of the square) of the through hole 70a formed in the columnar body 70 was 1.2 mm. The number (cell density) of the through holes 70a opened in the end face of the columnar body 70 was 0.43 / mm ² . The length of the columnar body 70 in the direction in which the through hole 70a extends was 171 mm. Moreover, the outer diameter of the end surface of the columnar body 70 was 162 mm.

  The sealing material 304 was introduced into a part of the through holes 70a opened on both end surfaces of the columnar body 70 by the manufacturing method shown in the above embodiment and FIGS. That is, the first mask 200 a was attached to the first end surface of the columnar body 70, and the second mask 200 b was attached to the second end surface of the columnar body 70. Next, a slurry-like sealing material 304 was supplied into the rubber ring 302 placed on the surface of the base 300. Using the pressing means 400, the first end surface of the columnar body 70 to which the first mask 200a was stuck was pressed against the sealing material 304 in the rubber ring. The columnar body 70 pressed against the sealing material 304 is moved together with the rubber ring 302 in a direction substantially parallel to the surface of the pedestal 300 using the moving means 600 to separate the columnar body 70 and the rubber ring 302 from the pedestal 300. . The sealing step for the second end surface of the columnar body 70 was performed in the same manner as the sealing step for the first end surface. The thickness of the sealing material 304 stretched in the rubber ring 302 in each sealing step was 3 mm. The weight of the sealing material 304 supplied into the rubber ring 302 in each sealing step was 100 g. As the sealing material 304, a mixture of aluminum titanate raw material powder, an organic binder, a lubricant, and water (solvent) was used.

  After each sealing step, each mask is peeled off from each end face of the columnar body 70, and the columnar body 70 is dried and baked, so that an embodiment made of a porous aluminum titanate crystal as shown in FIGS. 1 honeycomb structure 170 was obtained. In the manufacture of the honeycomb structure 170 of Example 1, it was confirmed that detachment of the sealing material 304 from the through hole 70a was suppressed. That is, as shown in FIG. 8, the sealing material 304 is introduced into the end portion of the through hole 70a that overlaps the opening portion 270a of the first mask 200a on the first end surface side, and the sealing portion 70b is formed. Was confirmed. It was confirmed that the sealing material 304 was not introduced into the through-hole 70a that was blocked by the mask portion 270b of the first mask 200a on the first end surface side, and the sealing portion 70b was not formed. It was confirmed that the sealing material 304 was introduced into the end portion of the through hole 70a that overlapped the opening portion of the second mask 200b on the second end face side, and the sealing portion 70b was formed. It was confirmed that the sealing material 304 was not introduced into the through-hole 70a that was blocked by the mask portion 270b of the second mask 200b on the second end face side, and the sealing portion 70b was not formed. The through hole 70a closed by the sealing part 70b on the first end face side is open on the second end face side, and the through hole 70a closed by the sealing part 70b on the second end face side is on the first end face side. Confirmed to be open.

  As shown in FIG. 8, the honeycomb structure 170 of Example 1 was cut perpendicularly to the end face, and the length D in the longitudinal direction of the through hole 70a of the sealing portion 70b that plugs one end of each through hole 70a was measured. did. The length D at the center of the end face of the honeycomb structure 170 tended to be longer than the length D at the peripheral edge of the end face. The maximum value of the length D was 10.00 mm. The minimum value of the length D was 6.00 mm. The average value of the length D was 9.13. The standard deviation σ of the length D was 0.79 mm.

(Example 2)
In Example 2, as shown in FIG. 9, a tapered rubber ring 302a having an inner diameter substantially the same as the outer diameter of the end surface of the columnar body 70 was used as the frame 302a. The tapered rubber ring 302a is placed on the surface of the pedestal 300 with the side with the largest inner diameter of the tapered rubber ring 302a facing away from the surface of the pedestal 300, and the sealing material 304 is attached to the tapered rubber ring 302a. Supplied.

  In Example 2, the thickness of the sealing material 304 stretched in the tapered rubber ring 302a in each sealing step was 2.5 mm. In Example 2, the weight of the sealing material 304 supplied into the tapered rubber ring 302 in each sealing step was 80 g. In Example 2, the entire columnar body 70 was vibrated by a vibrator after the sealing step for the first end surface. Further, after the sealing step for the second end face, the entire columnar body 70 was vibrated by a vibrator. After these vibration steps, the columnar body 70 was dried and fired.

  Except for the above, a honeycomb structure of Example 2 made of porous aluminum titanate-based crystals was formed in the same manner as Example 1. In the manufacture of the honeycomb structure of Example 2, it was confirmed that detachment of the sealing material 304 from the through hole 70a was suppressed. In the honeycomb structure of Example 2, as in Example 1, the through-hole 70a closed by the sealing portion 70b on the first end surface side is open on the second end surface side, and on the second end surface side. It was confirmed that the through hole 70a closed by the sealing portion 70b is open on the first end face side.

  In the same manner as in Example 1, the length D of the sealing portion 70b that plugs one end of each through hole 70a of the honeycomb structure of Example 2 was measured. The length D at the center of the end face of the honeycomb structure tended to be longer than the length D at the peripheral edge of the end face. The maximum value of the length D was 6.00 mm. The minimum value of the length D was 2.30 mm. The average value of the length D was 5.12. The standard deviation σ of the length D was 0.86 mm. In Example 2, it was confirmed that the length D was a uniform length of 4 ± 2 mm.

  70 ... columnar body, 70a ... through hole, 70b ... sealing part, 70c ... partition, 200a ... first mask, 200b ... second mask, 270a ... opening, 270b ... Mask part, 300 ... Base, 302, 302a ... Frame, 304 ... Sealing material, 400 ... Pressing means, 600 ... Moving means, 170 ... Honeycomb structure .

Claims (2)

A pedestal,
A frame placed on the surface of the pedestal;
A mask that is installed on an end face of the columnar body in which a plurality of through-holes are formed, has a plurality of mask portions and openings, and closes some of the through-holes with the mask portions;
A pressing means for pressing the end face of the columnar body provided with the mask against a slurry-like sealing material supplied into the frame;
Moving means for moving the columnar body pressed against the sealing material together with the frame in a direction substantially parallel to the surface of the pedestal;
Comprising
An apparatus for manufacturing a honeycomb structure. The frame is a rubber-like frame;
The manufacturing apparatus of the honeycomb structure according to claim 1.

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