JP2009255030A - Honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a honeycomb structure that has higher strength against stress from its outer circumferential side than a prior art honeycomb structure and does not generate a crack during its use. <P>SOLUTION: The honeycomb structure constituted of columnar honeycomb units each containing inorganic particles and an inorganic binder and comprising a plurality of cells extending along the longitudinal direction thereof from a first end face to a second end face thereof with the cells partitioned by cell walls, is characterized in that the cell walls are constructed along a first and a second directions substantially mutually intersecting at right angles upon viewing from the first end face side, the honeycomb structure is constituted of four honeycomb units bound together via an adhesive layer extending along two extending directions substantially mutually intersecting at right angles upon viewing from the first end face side, and the first direction of the cell walls is disposed in a manner forming the minimum angle of 22.5° to 45° relative to the extending direction of the adhesive layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a honeycomb structure for treating exhaust gas.

  Conventionally, a honeycomb structure is used in an exhaust gas treatment apparatus used for treating HC, CO, NOx, SOx, and the like contained in automobile exhaust gas. This honeycomb structure has, for example, a plurality of cells (through holes) extending from one end face of the honeycomb structure to the other end face along the longitudinal direction, and these cells are mutually connected by cell walls. It is partitioned.

  A catalyst such as platinum is installed on the cell wall of the honeycomb structure. When exhaust gas is circulated through such a catalyst carrier, the exhaust gas can be treated by a catalytic reaction of components of HC, CO, NOx, and SOx contained in the exhaust gas by the catalyst installed on the cell wall.

  As such a honeycomb structure, as disclosed in Patent Document 1, a first form of inorganic material (for example, ceramic particles), a second form of inorganic material (for example, inorganic fibers, and large-sized inorganic particles) , A honeycomb structure including an inorganic binder) is shown.

In addition, as a honeycomb structure used as a DPF (diesel particulate filter), first, in a columnar honeycomb unit having the same shape, side surfaces are bonded to each other via an adhesive layer, so that a predetermined number of honeycomb units are bonded. It is manufactured by binding and then cutting the outer periphery of the assembly into a desired shape (Patent Document 2). Alternatively, by preparing honeycomb units of a predetermined shape in advance and combining them through an adhesive layer, a honeycomb structure of a desired shape is manufactured without a cutting step (Patent Document 3). For example, Patent Document 3 discloses a technique for manufacturing a honeycomb structure by combining a total of 16 honeycomb units including three different shapes.
International Publication No. WO2005 / 063653 Pamphlet JP 2001-190916 A JP 2006-233983 A

  The honeycomb structure of Patent Document 1 has a problem that it is weak in strength. Therefore, even if the adhesive layer of the honeycomb structure of Patent Document 1 is configured as in Patent Document 2, the cell wall is formed to be parallel to the adhesive layer, and the honeycomb structure is formed by a relatively small stress from the outside. There is a problem that can easily be destroyed.

  Further, in the above-mentioned Patent Document 3, in the honeycomb structure formed by joining 16 members, when viewed from any end face side of the honeycomb structure in order to increase the strength against the stress from the outer peripheral direction. It has been proposed that the honeycomb structure is configured such that only in the smallest honeycomb unit at the four corners facing each other, the cell arrangement direction is rotated by 45 ° compared to the cells of other honeycomb units.

  However, in the case of the honeycomb structure described in Patent Document 3, the stress applied from the outside to the outer peripheral portion of the honeycomb structure is rotated by 45 ° with respect to the binding direction of the honeycomb units (for example, the vertical and horizontal directions with respect to the longitudinal direction of the cells). Most of the stress in the direction is directly applied to the minimum honeycomb unit at the four corners. Therefore, the portion of the honeycomb structure is easily damaged even by a relatively small external stress, and it is difficult to say that the strength is still sufficient in this honeycomb structure.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a honeycomb structure that has higher strength against stress from the outer peripheral side and does not generate cracks during use, as compared with the prior art. And

The honeycomb structure of the present invention includes a columnar honeycomb unit that includes inorganic particles and an inorganic binder, and a plurality of cells extending from the first end face to the second end face along the longitudinal direction are partitioned by cell walls. A honeycomb structure,
The cell wall is configured along first and second directions substantially orthogonal to each other when viewed from the first end face side,
When viewed from the first end face side, the honeycomb structure is configured by bonding four honeycomb units through adhesive layers extending along two extending directions substantially orthogonal to each other. ,
The first direction of the cell wall is arranged to form a minimum angle of 22.5 ° to 45 ° with respect to the extending direction of the adhesive layer.

  Here, the inorganic particles may include at least one material selected from the group consisting of alumina, ceria, zirconia, titania, silica, zeolite, and mullite.

  The inorganic binder may contain at least one material selected from the group consisting of alumina sol, silica sol, titania sol, water glass, sepiolite, and attapulgite.

  The honeycomb unit may further contain inorganic fibers.

  The inorganic fiber may be at least one selected from the group consisting of alumina, silica, silicon carbide, silica alumina, glass, potassium titanate, and aluminum borate.

  The honeycomb structure may have a circular, elliptical, or oval cross section when viewed from the first end face side.

  A catalyst may be supported on the cell wall. In particular, the catalyst may contain a noble metal, an alkali metal or an alkaline earth metal. For example, the catalyst may contain at least one material selected from the group of platinum, palladium and rhodium. Alternatively, the catalyst may contain at least one element selected from the group consisting of potassium, magnesium, barium and calcium.

  The zeolite may be ion-exchanged with Cu, Fe, Ni, Zn, Mn, or Co.

  In the present invention, it is possible to provide a honeycomb structure having higher strength against stress from the outer peripheral side than in the past.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows an example of a honeycomb structure 100 according to the present invention. FIG. 2 schematically shows an enlarged view of a cross section perpendicular to the longitudinal direction of the honeycomb structure 100 (hereinafter also simply referred to as “cross section”). FIG. 3 is a schematic perspective view of one honeycomb unit 120A constituting the honeycomb structure 100 of the present invention.

  As shown in FIG. 1, a honeycomb structure 100 according to the present invention has a first end face 105 and a second end face 106, and includes four honeycomb units 120 (120 </ b> A to 120 </ b> D) and the honeycomb units 120. And an adhesive layer 180 that binds the honeycomb units together.

  Note that the four honeycomb units 120A to 120D have substantially the same shape. Therefore, in the following description, the features of the honeycomb units 120A to 120D will be described by taking the honeycomb unit 120A as an example.

  The coat layer 190 shown in FIGS. 1 and 2 will be described later.

  As shown in FIG. 3, the honeycomb unit 120 </ b> A has a columnar shape with a quarter-circle cross-sectional shape having a substantially fan-shaped cross section. In the honeycomb unit 120A, a large number of cells 130A (through holes) partitioned by the cell walls 140A are provided along the longitudinal direction. In addition, the cross section perpendicular | vertical to the longitudinal direction of each cell 130A is substantially square shape, for example.

  1 and 2, the adhesive layer 180 extends in two directions orthogonal to each other. Hereinafter, these directions are referred to as a first stretching direction D1 (X direction in FIG. 2) and a second stretching direction D2 (Y direction in FIG. 2), respectively.

  In the example of FIG. 2, when viewed from the first end surface 105 side (or the second end surface 106 side) of the honeycomb structure 100, the cell walls 140A to 140D in the four honeycomb units 120A to 120D are It is configured in a lattice shape so as to extend along a straight line in two directions substantially perpendicular to the center line of the thickness of the cell wall. Hereinafter, these directions are referred to as “a first direction L1 (of the cell wall)” and “a second direction L2 (of the cell wall)”. The names “first” and “second” are for convenience, and one of the two directions is the “first” direction and the other is the “second” direction. is there. For example, in the example of FIG. 2, the direction rotated 45 ° counterclockwise with respect to the X axis (horizontal axis) is defined as the first direction L1, and 45 ° clockwise with respect to the X axis (horizontal axis). The rotated direction is defined as a second direction L2.

  In the example of FIG. 2, each cell wall 140 </ b> A has a first direction L <b> 1 (or a second direction L <b> 2) of 45 ° with respect to the two extending directions D <b> 1 and D <b> 2 of the adhesive layer 180. The honeycomb units 120A are arranged so as to form a “minimum angle”.

  In this application, it should be noted that the “minimum angle” means the smallest angle among the angles formed by one straight line group and the third straight line. 4A and 4B show the concept of this “minimum angle”. For example, as shown in FIG. 4A, a straight line group consisting of two straight lines A and B that are substantially orthogonal to each other, and a third straight line C rotated counterclockwise by 45 ° with respect to the straight line A. Is present, the angle formed by the straight line C and the straight line A is 45 ° or 135 °, and the angle formed by the straight line C and the straight line B is 45 ° or 135 °. In this case, the minimum angle formed by the straight line C and the straight line group is 45 ° as indicated by α or β in FIG. Accordingly, the “minimum angle” formed by the straight line C and the straight line group is 45 °. 4B, when the third straight line C is rotated 22.5 ° counterclockwise with respect to the straight line A, the angle formed by the straight line C and the straight line A is 22.2. The angle between the straight line C and the straight line B is 67.5 ° or 112.5 °. Therefore, in this case, the minimum angle among the angles formed by the straight line C and the straight line group is 22.5 ° which is the smaller of the angles formed by the straight line C and the straight line A. Therefore, the “minimum angle” formed by the straight line C and the straight line group is 22.5 °.

  In FIG. 2, in the honeycomb structure 100, the first direction L1 (or the second direction L2) of the cell wall 140A is a minimum angle of 45 ° with respect to the two extending directions D1 and D2 of the adhesive layer 180. It is comprised so that it may make. However, in the present invention, the minimum angle formed by the first direction L1 (or the second direction L2) of the cell wall 140A and the two extending directions D1 and D2 of the adhesive layer 180 is not limited to 45 °. . This minimum angle is preferably in the range of 22.5 ° to 45 °.

  Hereinafter, the characteristic effect of the honeycomb structure 100 of the present invention configured as described above will be described in comparison with the conventional honeycomb structure 200.

  FIG. 5 schematically shows a cross section perpendicular to the longitudinal direction of a conventional honeycomb structure 200. The conventional honeycomb structure 200 is configured by binding four honeycomb units 220 </ b> A to 220 </ b> D via an adhesive layer 280. The adhesive layer 280 extends along two orthogonal directions, that is, a first extending direction D1 (X direction in the figure) and a second extending direction D2 (Y direction in the figure). In the conventional honeycomb structure 200, the honeycomb units 220A to 220D have substantially the same shape. Therefore, in the following description, the features of the honeycomb units 220A to 220D will be described using the honeycomb unit 220A as an example. As is apparent from FIG. 5, in the conventional honeycomb structure 200, when viewed from one end face side of the honeycomb structure 200, the first direction L3 (or the second direction L4) of the cell wall 240A of the honeycomb unit 220A. ) Is configured along substantially the same direction as the two stretching directions D1 (or D2) of the adhesive layer 280. That is, the first arrangement direction L3 of the cell walls is equal to the first extending direction D1 of the adhesive layer 280, and the second arrangement direction L4 of the cells is equal to the second extending direction D2 of the adhesive layer. .

  Such a honeycomb structure 200 exhibits different strength characteristics depending on the location against external stress (compressive stress) applied to the outer peripheral surface of the honeycomb structure. In addition, a coat layer 290 is provided on the outer periphery of the honeycomb structure 200 to improve the strength against external stress.

  FIG. 6 is a cross-sectional view schematically showing stress from various directions applied to the outer peripheral surfaces of the honeycomb structures 200 and 100. For example, the honeycomb structure 200 exhibits high strength against stress (Pa) from the stretching directions D1 and D2 of the adhesive layer 280 as shown in FIG. 6 because the adhesive layer 280 functions as a reinforcing material. However, the honeycomb structure 200 has a low strength against stress from around 45 ° with respect to the extending directions D1 and D2 of the adhesive layer 280 as indicated by Pb in FIG.

  This is because the first and second directions (L3 and L4 in FIG. 5) of the cell wall 240A are substantially parallel to the directions D1 and D2, respectively. This is because the adhesive layer 280 cannot be relaxed (does not function as a reinforcing material).

  If there is even a weak part in the honeycomb structure, the honeycomb structure 200 is broken starting from that point, and the conventional honeycomb structure 200 is broken starting from stress from the Pa direction.

  For this reason, in order to increase the strength of the honeycomb structure, it is necessary to eliminate (reinforce) weak portions against external stress (compressive stress) applied to the honeycomb structure.

  In the honeycomb structure 100 according to the present invention, as described above, the first direction L1 (or the second direction L2) of the cell wall 140A is 22.5 with respect to the two extending directions D1 and D2 of the adhesive layer 180. It is comprised so that the minimum angle of (degrees)-45 degrees may be made. In such a configuration, the honeycomb structure 100 exhibits a more uniform strength against external stress applied from each direction on the outer periphery of the honeycomb structure for the following reason.

  2 and 6, first, when the honeycomb structure 100 receives stress Pa from the outside in the directions D1 and D2 parallel to one extending direction of the adhesive layer 180, the presence of the adhesive layer 180 as described above. Thus, high strength can be obtained. Next, when the honeycomb structure receives stress Pb in a direction that makes an angle of about 45 ° with respect to the extending directions D1 and D2 of the adhesive layer 180, high strength is maintained by the cell walls 140A of the honeycomb unit 120A. Is done. This is because in FIG. 2, the first or second direction L1, L2 of the cell walls 140A to 140D is configured to substantially coincide with the external stress direction Pb. Therefore, the honeycomb structure 100 according to the present invention exhibits substantially the same strength against the external stress in each direction of the outer peripheral surface, and as a whole, has a better strength than the conventional honeycomb structure 200. Can be obtained.

  As described above, in the honeycomb structure described in Patent Document 3, in order to increase the strength against external stress, when viewed from the end face side in the longitudinal direction of the honeycomb structure, the minimum honeycomb unit at the four corners facing each other. Only, the cell wall is configured such that the cell arrangement direction is rotated by 45 ° compared to other honeycomb units.

  When the structure of the conventional honeycomb structure described in Patent Document 3 is used in the present invention, 16 honeycomb units having at least three types of shapes are provided via an adhesive layer when the honeycomb structure is configured. It is necessary to join them with their positions aligned with each other. This is an extremely difficult operation. In practice, the mutual positions of the honeycomb units are slightly shifted, and the shape of the completed honeycomb structure often differs from a predetermined state.

  Further, as described above, in the honeycomb structure having the minimum honeycomb units at the four corners, the flow of the exhaust gas is not uniform. When the honeycomb structure is used as the DPF, the exhaust gas flows through the wall (wall flow), so that it can be used effectively. However, when the honeycomb structure is used as a catalyst carrier, it cannot be used effectively because of the straight flow. Accordingly, the efficiency of processing of harmful components in the exhaust gas, for example, processing of HC, CO, NOx, SOx, etc., may be reduced.

  On the other hand, in the honeycomb structure 200 according to the present invention, the four honeycomb units 120 </ b> A to 120 </ b> D are joined through the adhesive layer 180. Therefore, the number of joining members is small, and the problem of positional deviation as described above can be significantly suppressed. In the completed honeycomb structure 100, the first and second directions (L1, L2) of the cell walls 140A to 140D of the honeycomb units 120A to 120D are substantially the same. Therefore, in the honeycomb structure of the present invention, the above-described problem that the exhaust gas flow is uneven and the processing efficiency is lowered is significantly reduced.

  In the above-described example, four honeycomb units 120A to 120D each having a substantially fan-shaped cross section perpendicular to the longitudinal direction are bundled through the adhesive layer 180, thereby directly forming a honeycomb structure having a desired outer peripheral shape. The honeycomb structure of the present invention has been described by taking the case of the configuration as an example. However, the present invention is not limited to such a configuration. FIG. 7 schematically shows another example of the honeycomb unit 121 constituting the honeycomb structure of the present invention. It is also possible to obtain a honeycomb structure having a desired outer peripheral shape by binding four rectangular column-shaped honeycomb units 121 as shown in FIG. 7 through an adhesive layer and then cutting the periphery.

  Further, the honeycomb structure 100 shown in FIG. 1 has a cylindrical shape with a substantially circular cross section. However, the honeycomb structure of the present invention is not limited to a cylindrical shape, for example, an elliptical column shape or a long column shape. Any shape may be used.

  The above-described configuration of the honeycomb structure 100 assumes that the honeycomb structure according to the present invention is used as a catalyst carrier. When the honeycomb structure 100 according to the present invention is used, for example, for processing predetermined components in exhaust gas, such as HC, CO, NOx, or SOx, the cell walls 140A to 140D promote the processing reaction of these components. Catalysts such as alkali metals and alkaline earth metals may be supported. Further, a catalyst may be woven into the base material of the honeycomb structure 100.

  Such a honeycomb structure 100 according to the present invention can be used, for example, in an exhaust gas treatment apparatus for a vehicle.

  FIG. 8 schematically shows an example of the exhaust gas treatment device 70 to which the honeycomb structure 100 according to the present invention is attached. As shown in FIG. 8, the exhaust gas treatment device 70 is mainly disposed in the honeycomb structure 100, the metal casing 71 that houses the honeycomb structure 100, and the honeycomb structure 100 and the casing 71. The holding sealing material 72 holds the 100 in an appropriate position. An exhaust pipe 74 for introducing exhaust gas discharged from an internal combustion engine such as an engine is connected to one end portion (introduction portion) of the exhaust gas treatment device 70, and the other end of the exhaust gas treatment device 70 is connected. A discharge pipe 75 for discharging exhaust gas is connected to the section (discharge section). In FIG. 8, arrows indicate the flow of exhaust gas.

  Exhaust gas discharged from an internal combustion engine such as an engine passes through the introduction pipe 74 and is introduced into the casing 71, and each cell from one end face (for example, the first end face) of the honeycomb structure 100 facing the introduction pipe 74. Is flowed into. The exhaust gas that has flowed into the cell passes through the same cell and is discharged out of the system. In this process, harmful substances in the exhaust gas can be purified.

In the present invention, the cell density of the honeycomb unit 120 is preferably in the range of 15.5 to 186 cells / cm ² (100 to 1200 cpsi), and in the range of 46.5 to 170 cells / cm ² (200 to 1000 cpsi). more preferably, more preferably in the range of 62.0 to 155 cells ^/ cm 2 ^{(300~800cpsi).}

  The thickness of the cell wall 140 of the honeycomb unit 120 is not particularly limited, but a desirable lower limit is 0.1 mm from the viewpoint of strength, and a desirable upper limit is 0.4 mm.

The specific surface area of the honeycomb unit 120 is not particularly ^limited, is preferably in the range of 25000m ² / L~70000m 2 / L.

  The honeycomb unit 120 constituting the honeycomb structure 100 of the present invention is not particularly limited, but preferably includes inorganic particles and an inorganic binder, and may further include inorganic fibers.

  As the inorganic particles, particles made of alumina, ceria, zirconia, titania, silica, zeolite, mullite, or the like are desirable. These particles may be used alone or in combination of two or more.

  When zeolite is used as the inorganic particles, zeolite ion-exchanged with Cu, Fe, Ni, Zn, Mn or Co may be used. The ion-exchanged zeolite may be used alone, or two or more types may be combined, or the same type and different metal valences may be used.

  The inorganic fiber is preferably made of alumina, silica, silicon carbide, silica-alumina, glass, potassium titanate or aluminum borate. These may be used alone or in combination of two or more. Among the inorganic fibers, alumina is more preferable.

  In addition, in this specification, an inorganic fiber means that whose average aspect ratio (length / diameter) exceeds 5. Moreover, the desirable average aspect-ratio of the said inorganic fiber is 10-1000.

  As the inorganic binder, an inorganic sol, a clay-based binder, or the like can be used, and specific examples of the inorganic sol include alumina sol, silica sol, titania sol, water glass, and the like. In addition, examples of the clay-based binder include double chain structure type clays such as clay, kaolin, montmorillonite, sepiolite, attapulgite, and the like. These may be used alone or in combination of two or more.

  Among these, it is desirable that at least one selected from the group consisting of alumina sol, silica sol, titania sol, water glass, sepiolite, and attapulgite is included.

  With respect to the amount of the inorganic particles contained in the honeycomb unit 120, a preferable lower limit is 30% by weight, a more preferable lower limit is 40% by weight, and a further preferable lower limit is 50% by weight. On the other hand, a preferable upper limit is 90% by weight, a more preferable upper limit is 80% by weight, and a further preferable upper limit is 75% by weight.

  When the content of inorganic particles is less than 30% by weight, the amount of inorganic particles contributing to the catalytic action is relatively small. On the other hand, if it exceeds 90% by weight, the amount of inorganic fibers contributing to the strength improvement is relatively reduced, and thus the strength of the honeycomb unit 120 may be reduced.

  A desirable lower limit for the total amount of the inorganic fibers contained in the honeycomb unit 120 is 3% by weight, a more desirable lower limit is 5% by weight, and a further desirable lower limit is 8% by weight. On the other hand, the desirable upper limit is 50% by weight, the more desirable upper limit is 40% by weight, and the more desirable upper limit is 30% by weight.

  If the inorganic fiber content is less than 3% by weight, the strength of the honeycomb unit 120 may be reduced, and if it exceeds 50% by weight, the amount of inorganic particles contributing to the purification performance is relatively reduced. For example, when the honeycomb structure has a small specific surface area and supports the catalyst component, the catalyst component cannot be highly dispersed, or the amount of catalyst per unit volume may decrease.

  The desired lower limit of the amount of the inorganic binder contained in the raw material composition is a solid content with respect to the total solid content of the inorganic particles, the inorganic fibers and the inorganic binder contained in the raw material composition. The lower limit is 5% by weight, a more desirable lower limit is 10% by weight, and a further desirable lower limit is 15% by weight. On the other hand, the desirable upper limit is 50% by weight, the more desirable upper limit is 40% by weight, and the further desirable upper limit is 35% by weight.

  When the amount of the inorganic binder is less than 5% by weight as the solid content, the strength of the manufactured honeycomb unit 120 may be low. On the other hand, when the amount of the inorganic binder exceeds 50% by weight as the solid content, There is a tendency for the moldability of the to become worse.

  The adhesive layer 180 constituting the honeycomb structure 100 of the present invention may be dense or porous. Although the material which comprises the contact bonding layer 180 is not specifically limited, For example, what consists of an inorganic binder, an organic binder, an inorganic fiber, and / or an inorganic particle can be used.

  As the inorganic binder for the adhesive layer, for example, those containing silica sol, alumina sol, titania sol and the like can be used, and these may be used alone or in combination of two or more. .

  As the organic binder for the adhesive layer 180, for example, polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose and the like can be used. These may be used alone or in combination of two or more. Also good.

  As the inorganic fibers for the adhesive layer 180, for example, ceramic fibers such as silica-alumina, mullite, alumina, and silica can be used. These may be used alone or in combination of two or more.

  As the inorganic particles for the adhesive layer 180, those previously shown as the material for the honeycomb unit 120 can also be used. These may be used alone or in combination of two or more.

  The adhesive layer 180 is formed by preparing a paste containing the above components as a raw material, placing the paste at a predetermined location, and drying it. If necessary, a pore-forming agent such as balloons that are fine hollow spheres containing oxide-based ceramics, spherical acrylic particles, and graphite may be added to the raw material paste.

  In the honeycomb structure 100 described above, a coat layer 190 may be further provided on the outer peripheral surface. By installing the coat layer 190, the strength of the outer peripheral surface of the honeycomb structure 100 is further improved.

The thickness of the coat layer 190 is not particularly limited, but is preferably in the range of 0.2 to 3.0 mm. The coat layer 190 may be the same material as the adhesive layer 180 or a different material.
(Manufacturing method of honeycomb structure)
Next, a method for manufacturing the honeycomb structure 100 of the present invention will be described. First, extrusion molding or the like is performed using the above-described raw material paste mainly composed of ceramic particles, inorganic fibers, and an inorganic binder, and a honeycomb unit molded body is manufactured. In addition to these, an organic binder, a dispersion medium, and a molding aid may be appropriately added to the raw material paste in accordance with the moldability. The organic binder is not particularly limited, and examples thereof include one or more organic binders selected from methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, epoxy resin, and the like. The blending amount of the organic binder is preferably 1 to 10 parts by weight with respect to a total of 100 parts by weight of the ceramic particles, inorganic fibers, and inorganic binder. Although it does not specifically limit as a dispersion medium, For example, water, an organic solvent (benzene etc.), alcohol (methanol etc.), etc. can be mentioned. Although it does not specifically limit as a shaping | molding adjuvant, For example, ethylene glycol, dextrin, a fatty acid, fatty-acid soap, a polyalcohol etc. can be mentioned.

  The raw material paste is not particularly limited, but is preferably mixed and kneaded. For example, the raw material paste may be mixed using a mixer or an attritor, or may be sufficiently kneaded using a kneader. Although the method of shape | molding raw material paste is not specifically limited, For example, it is preferable to shape | mold into the shape which has a cell by extrusion molding etc. (refer FIG. 3).

  Next, the obtained honeycomb unit molded body is preferably dried. The dryer used for drying is not particularly limited, and examples thereof include a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, and a freeze dryer. The obtained honeycomb unit molded body is preferably degreased. The degreasing conditions are not particularly limited, and are appropriately selected depending on the type and amount of organic matter contained in the molded body, but are preferably about 400 ° C. and 2 hours. Furthermore, it is preferable that the obtained molded body is fired. Although it does not specifically limit as baking conditions, About 2 hours are preferable at 600-1200 degreeC, and about 2 hours are more preferable at 600-1000 degreeC. This is because if the firing temperature is less than 600 ° C., the sintering is difficult to proceed, the strength as the honeycomb unit 120 is low, and if it exceeds 1200 ° C., the sintering proceeds too much, and the ratio per unit volume of the honeycomb unit 120 This is because the surface area becomes small. Through these steps, a honeycomb unit having a plurality of cells can be obtained.

  Next, an adhesive layer paste that will later become the adhesive layer 180 is applied to the side surface of the honeycomb unit with a uniform thickness, and then another honeycomb unit 120 is sequentially laminated through the adhesive layer paste. This process is repeated to produce a honeycomb structure 100 having a desired dimension (for example, two honeycomb units 120 are arranged vertically and horizontally). The above-mentioned raw material paste may be used for the adhesive layer paste.

  The adhesive layer paste is not particularly limited, but for example, a mixture of an inorganic binder and ceramic particles, a mixture of inorganic binder and inorganic fibers, or a mixture of inorganic binder, ceramic particles and inorganic fibers. Can be used. Moreover, it is good also as what added the organic binder to these sealing materials. Although it does not specifically limit as an organic binder, For example, 1 or more types chosen from polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose, etc. are mentioned.

  The thickness of the adhesive layer 180 to which the honeycomb unit is bonded is preferably 0.3 to 2.0 mm. This is because if the thickness of the adhesive layer is less than 0.3 mm, sufficient bonding strength may not be obtained. In addition, since the adhesive layer 180 is a portion that does not function as a catalyst carrier, when the thickness exceeds 2.0 mm, the specific surface area per unit volume of the honeycomb structure 100 decreases, and the dispersion is sufficiently high when the catalyst component is supported. In some cases, the purification performance may be deteriorated due to the fact that the amount of catalyst per unit volume of the honeycomb structure 100 cannot be reduced. Further, when the thickness of the adhesive layer exceeds 2.0 mm, the pressure loss may increase.

  Next, the honeycomb structure is heated to dry and solidify the adhesive layer paste, thereby forming an adhesive layer and fixing the honeycomb units to each other.

  A columnar honeycomb structure 100 as shown in FIG. 1, which includes four honeycomb units 120 having a fan-shaped cross section as shown in FIG. 3, can be produced.

  Further, the coat layer paste may be applied to the outer peripheral surface of the honeycomb structure 100, dried and solidified to form the coat layer 190. The coating layer paste is not particularly limited, but may be the same as or different from the adhesive layer paste. The coating layer paste may have the same blending ratio as the adhesive layer paste, or a different blending ratio. Although the thickness of a coat layer is not specifically limited, 0.2 mm-3.0 mm are desirable.

  After the plurality of honeycomb units 120 are joined by the adhesive layer 180 (however, when a coat layer is provided, after the coat layer is formed), the honeycomb structure is preferably heat-treated. Thereby, when the organic binder is contained in the paste for adhesive layers and the paste for coat layers, these can be degreased and removed. The degreasing conditions vary depending on the type and amount of organic matter contained, but approximately 700 ° C. and 2 hours are preferable.

When the catalyst is supported on the cell wall 140 of the honeycomb structure 100, the catalyst material is not particularly limited, and examples thereof include noble metals such as platinum, palladium, and rhodium. Further, a compound containing an alkali metal, an alkaline earth metal, a rare earth element, a transition metal, or the like may be supported. As a method of installing a platinum catalyst, for example, a honeycomb unit provided with a catalyst supporting layer is impregnated with a dinitrodiammine platinum nitric acid solution ([Pt (NH ₃ ) ₂ (NO ₂ ) ₂ ] HNO ₃ ) and heated. And the like. The catalyst may contain one of potassium, magnesium, barium, and calcium.

  Hereinafter, the present invention will be described in detail by way of examples.

  First, 2250 parts by weight of zeolite, 680 parts by weight of alumina fibers (average fiber length 100 μm, average fiber diameter 6 μm), 2600 parts by weight of alumina sol (solid content 30 wt%), and 320 parts by weight of methylcellulose are mixed with a plasticizer and a lubricant (unilube). Mixing and kneading were performed to obtain a mixed composition. Next, this mixed composition was subjected to extrusion molding with an extruder to obtain a honeycomb unit molded body having a cross-sectional fan shape (cross-sectional shape of ¼ circle (radius 69 mm)). In the honeycomb unit 120, when viewed from the end face of the honeycomb unit, the first and second directions of the cell wall are substantially orthogonal, and the first and second directions (L1, L2) of the cell wall Was inclined by 45 ° with respect to a straight line forming a sectional fan shape (radius of ¼ circle in cross section). Accordingly, each cell wall has a “minimum angle” of 45 ° in the first direction L1 (or second direction L2) of the cell wall with respect to the two extending directions of the adhesive layer in the completed honeycomb structure. It was configured to make.

Next, these molded bodies were sufficiently dried using a microwave dryer and a hot air dryer, and degreased by holding at 400 ° C. for 2 hours. Thereafter, firing was carried out by holding at 700 ° C. for 2 hours to obtain a honeycomb unit 120 (a columnar body having a sectoral fan shape having two sides of 69 mm on one side and an arc). The thickness of the cell wall 140 was 0.2 mm, and the cell density was 93 cells / cm ² .

  Next, 26% by mass of alumina particles (average particle size 2 μm), 37% by mass of alumina fibers, 31.5% by mass of alumina sol (solid content 30 wt%), 0.5% by mass of carboxymethylcellulose, and 5% by mass of water were mixed. Thus, an adhesive layer paste was prepared. This adhesive layer paste was applied to the side surface of each honeycomb unit 120, and a total of four honeycomb units in two rows and two rows were joined to obtain a honeycomb aggregate. The adhesive layer paste was uniformly applied to the honeycomb unit 120 so that the thickness of the completed adhesive layer was 1 mm, and then solidified by heating at 120 ° C.

  Next, a coat layer paste (same as the adhesive layer paste) was applied to the outer periphery of the honeycomb aggregate, and heated and solidified to form a coat layer 190 having a thickness of 0.5 mm.

  Through such a process, the honeycomb structure 100 according to Example 1 was obtained.

  A honeycomb structure 100 was produced by the same method as in Example 1. However, in Example 2, the first direction L1 (or the second direction L2) of the cell wall 140 in the completed honeycomb structure 100 is 40 ° with respect to the two extending directions of the adhesive layer 180. Each honeycomb unit was manufactured so as to form a “minimum angle”.

  A honeycomb structure 100 was produced by the same method as in Example 1. However, in Example 3, the first direction L1 (or the second direction L2) of the cell wall 140 in the completed honeycomb structure 100 is 22.5 ° with respect to the two extending directions of the adhesive layer 180. Each honeycomb unit was manufactured so as to have the “minimum angle”.

Comparative Example 1

  A honeycomb structure 100 was produced by the same method as in Example 1. However, in the comparative example 1, in the completed honeycomb structure 100, the first direction L1 (or the second direction L2) of the cell wall 140 is 10 ° with respect to the two extending directions of the adhesive layer 180. Each honeycomb unit was manufactured so as to form a “minimum angle”.

Comparative Example 2

A honeycomb structure 100 was produced by the same method as in Example 1. However, in Comparative Example 2, each honeycomb unit was manufactured such that in the completed honeycomb structure 100, the first direction L1 of the cell wall 140 coincided with each extending direction of the adhesive layer 180. Accordingly, the “minimum angle” formed by the first direction L1 (or the second direction L2) of the cell wall 140 with respect to the two extending directions of the adhesive layer 180 is 0 °.
[Isostatic strength measurement]
Isostatic strength was measured using the honeycomb structures 100 according to Examples 1 to 3 and Comparative Examples 1 and 2 manufactured as described above. Here, the isostatic strength is a compressive fracture load when fracture occurs when an isotropic hydrostatic pressure load is applied to the honeycomb structure. -87.

  Isostatic strength was measured as follows. A metal plate (aluminum plate: thickness 15 mm) is installed on both opening surfaces of the honeycomb structure. Next, the honeycomb structure and the metal plate are wrapped in a urethane rubber sheet (thickness 2 mm) and sealed. Next, this sealed body is completely immersed in a container containing water. In this state, the water pressure is increased and the water pressure at which the honeycomb structure is broken is measured.

  The results obtained for each honeycomb structure 100 are summarized in Table 1. Further, FIG. 9 shows a “minimum angle” (the cell wall 140 and the adhesive layer 180 between the first arrangement direction L1 of the cell walls 140 and the extending direction of the adhesive layer in the honeycomb structure 100 according to the example and the comparative example. The relationship between the angle and the isostatic strength is shown.

図９は、実施例および比較例に係るハニカム構造体１００のアイソスタティック強度と「最小角度」との関係を示したグラフである。

FIG. 9 is a graph showing the relationship between the isostatic strength and the “minimum angle” of the honeycomb structure 100 according to the example and the comparative example.

  From the results of Table 1 and FIG. 9, the honeycomb structure 100 in which the “minimum angle” between the first direction of the cell wall and the two extending directions L1 of the adhesive layer 180 is 22.5 ° to 45 ° (Example 1) In 3), it can be seen that the isostatic strength is significantly improved as compared with the honeycomb structures having the “minimum angle” of 0 ° to 10 ° (Comparative Examples 1 and 2).

1 is a perspective view schematically showing an example of a honeycomb structure of the present invention. FIG. 2 is a schematic enlarged view of a cross section perpendicular to the longitudinal direction of the honeycomb structure of FIG. 1. FIG. 2 is a perspective view schematically showing an example of a honeycomb unit constituting the honeycomb structure of FIG. 1. It is the figure which showed the definition of the "minimum angle" which a straight line group and a 3rd straight line make. FIG. 6 is a schematic enlarged view of a cross section perpendicular to the longitudinal direction of a conventional honeycomb structure. It is the figure which showed typically the stress from each direction applied to the outer peripheral surface of a honeycomb structure. FIG. 2 is a perspective view schematically showing another example of a honeycomb unit constituting the honeycomb structure of FIG. 1. It is sectional drawing which showed typically an example of the waste gas processing apparatus in which the honeycomb structure of this invention was installed. It is a graph which shows the relationship between the angle | corner which the cell of the honeycomb structure which concerns on an Example and a comparative example, and the contact bonding layer, and isostatic strength.

Explanation of symbols

DESCRIPTION OF SYMBOLS 70 Exhaust-gas processing apparatus 71 Casing 72 Holding | maintenance sealing material 74 Introducing pipe 75 Exhaust pipe 100 Honeycomb structure 120 (120A-120D) Honeycomb unit 121 Another honeycomb unit 130 (130A-130D) Cell 140 (140A-134D) Cell wall 180 Adhesive layer 190, 290 Coat layer 200 Conventional honeycomb structure 220 (220A to 220D) Honeycomb unit 280 Adhesive layer L1, L2 Cell wall direction D1, D2 Stretch direction of adhesive layer

Claims (11)

A honeycomb structure including a columnar honeycomb unit including inorganic particles and an inorganic binder, and a plurality of cells extending from a first end surface to a second end surface along a longitudinal direction are partitioned by cell walls,
The cell wall is configured along first and second directions substantially orthogonal to each other when viewed from the first end face side,
When viewed from the first end face side, the honeycomb structure is configured by bonding four honeycomb units through adhesive layers extending along two extending directions substantially orthogonal to each other. ,
The honeycomb structure according to claim 1, wherein the first direction of the cell wall is disposed so as to form a minimum angle of 22.5 ° to 45 ° with respect to the extending direction of the adhesive layer.   The honeycomb structure according to claim 1, wherein the inorganic particles include at least one material selected from the group consisting of alumina, ceria, zirconia, titania, silica, zeolite, and mullite.   The honeycomb structure according to claim 1 or 2, wherein the inorganic binder includes at least one material selected from the group consisting of alumina sol, silica sol, titania sol, water glass, sepiolite, and attapulgite.   The honeycomb structure according to any one of claims 1 to 3, wherein the honeycomb unit further includes an inorganic fiber.   The honeycomb structure according to claim 4, wherein the inorganic fiber is at least one selected from the group consisting of alumina, silica, silicon carbide, silica alumina, glass, potassium titanate, and aluminum borate.   The honeycomb structure according to any one of claims 1 to 5, wherein the honeycomb structure has a circular, elliptical, or oval cross section when viewed from the first end face side. .   The honeycomb structure according to any one of claims 1 to 6, wherein a catalyst is supported on the cell wall.   The honeycomb structure according to claim 7, wherein the catalyst contains a noble metal, an alkali metal, or an alkaline earth metal.   The honeycomb structure according to claim 8, wherein the catalyst includes at least one material selected from the group consisting of platinum, palladium, and rhodium.   The honeycomb structure according to claim 8, wherein the catalyst contains at least one element selected from the group consisting of potassium, magnesium, barium and calcium.   The honeycomb structure according to claim 2, wherein the zeolite is ion-exchanged with Cu, Fe, Ni, Zn, Mn, or Co.

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