JP2013202532A - Honeycomb filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of cracks by the heat shock caused by the thermal expansion difference between a honeycomb structure and a seal part without inhibiting the material selection of the seal part or the degree of freedom of the setting of porosity, without promoting the accumulation of PM in the seal part or without generating the irregularity in the purification function of PM between cells.SOLUTION: The differences between the respective longitudinal and lateral coefficients of thermal expansion of a honeycomb structure 10 and a seal part 13 are both below 0.5×10/°C and the differences between the individual longitudinal coefficients and the individual lateral coefficients, of thermal expansion, are below 3.5×10/°C. Further, in a case that the longitudinal and lateral coefficients of thermal expansions in the honeycomb structure 10 and the seal part 13 are respectively supposed as vectors, the difference of the angles θh and θm taken by the expansion vectors Zh and Zm being those resultant vectors with the axial direction is below 15°.

Description

  The present invention relates to a honeycomb filter used as an exhaust gas purifying filter for removing particulate matter contained in exhaust gas of an internal combustion engine, particularly a diesel engine.

As a filter that is provided in an exhaust passage of an internal combustion engine and collects particulate matter contained in exhaust gas, an exhaust gas purification filter using a porous ceramic material is widely used. In particular, particulate matter (PM) contained in exhaust gas from diesel vehicles, together with nitrogen oxides (NOx), emission regulations are being strengthened in stages in Japan, the United States, and Europe. In order to meet such regulations, development of a diesel particulate filter (DPF: Diesel Particulate Filter) for collecting particulate matter has been actively promoted. Currently, a wall flow type having a honeycomb structure is mainly used as the DPF.

  Such a honeycomb filter has a honeycomb structure in which a large number of cells including through-holes are regularly formed with the axial direction of the honeycomb filter as the extending direction. The honeycomb structure is made of a porous ceramic fired body. Any end face in the axial direction of the honeycomb filter (cell extending direction) in each cell is plugged with a plugging portion. Sealing is performed on different end faces between adjacent cells.

  For example, in Patent Document 1, there is a difference in thermal expansion between the filter portion (honeycomb structure) and the plugged portion, and stress is concentrated on the boundary between the filter portion and the plugged portion due to thermal shock. In order to prevent the occurrence of cracks in the portion, a configuration in which the plugging thickness is made non-uniform is disclosed.

  Further, in Patent Document 2, if the plugging portion is a dense filler, the columnar body (honeycomb structure) and the plugging portion have different thermal expansion coefficients. In order to prevent a gap or a crack from being generated due to a large thermal stress acting between the sealing portion and the porosity of the columnar body is 20 to 80%, the porosity of the plugging portion is 90%. In the following, a configuration that makes the porosity of the columnar body 0.15 to 4 times is disclosed.

Japanese Patent No. 3012167 Japanese Patent No. 4386830

  However, in the technique of Patent Document 1, since the plugging thickness is not uniform, the length in the axial direction of the cell forming the filter function differs among the plurality of cells constituting the honeycomb filter. As a result, the PM purification function varies between cells, and there is a problem that the purification quality is not sufficiently stable as a honeycomb filter.

  Note that it is also conceivable that the filter portion and the plugging portion are made of the same material to eliminate the difference in thermal expansion between them. However, in this case, since the porosity of the plugged portion is the same as that of the filter portion, the degree of freedom in designing the material selection of the plugged portion cannot be obtained.

On the other hand, in the technique of Patent Document 2, the porosity of the plugged portion is regulated by the porosity of the columnar body.
For example, when the porosity of the columnar body is 80%, the porosity of the plugged portion needs to be 12 (= 80 × 0.15)% or more. When the porosity of the plugged portion is limited by the porosity of the columnar body, the degree of freedom in designing the porosity of the plugged portion cannot be obtained.

  Further, since the porosity of the plugged portion becomes relatively large, PM of the exhaust gas enters and accumulates in the pores of the plugged portion by the PM purification process. Since PM deposited in the plugging portion burns during regeneration heating of the honeycomb filter, the temperature of the plugging portion rises, the difference in thermal expansion between the plugging portion and the columnar body increases, and the thermal shock resistance May be disturbed.

  The present invention has been made in view of the above problems, and its purpose is to prevent generation of cracks due to thermal shock caused by a difference in thermal expansion between the honeycomb structure and the plugged portion, and to provide a material for the plugged portion. To inhibit the freedom of selection and porosity setting without inhibiting PM deposition in the plugged portion or causing variation in the PM purification function between cells. is there.

  As a result of intensive studies to achieve the above object, the inventors of the present invention focused on the difference in the vertical and horizontal thermal conductivities of the substances constituting the honeycomb structure and the plugged portions. In other words, even if there is a difference in thermal expansion coefficient between the materials constituting the honeycomb structure and the plugging portion, if the difference between the vertical and horizontal thermal expansion coefficients is small in each material, the honeycomb structure and the plugging are sealed. It was found that slippage due to the difference in thermal expansion at the joint surface with the stop portion is less likely to occur, and it was found that cracking due to thermal shock during production or use due to thermal expansion can be suppressed, leading to the present invention.

In order to solve the above problems, a honeycomb filter of the present invention includes a honeycomb structure including a fired body having a plurality of cells extending in one direction formed by being partitioned by cell walls, and the plurality of cells A honeycomb filter in which one end portion in the extending direction is plugged with a plugging portion, and the honeycomb structure and the plugged portion have a thermal expansion in each of the extending direction and a direction orthogonal thereto. The difference in coefficient is both less than 0.5 × 10 ⁻⁶ / ° C., and the difference in the thermal expansion coefficient in the stretching direction and the difference in thermal expansion coefficient in the direction orthogonal to the stretching direction are both 3.5 ×. Less than 10 ⁻⁶ / ° C., and in the honeycomb structure, the direction in which the stretching direction is oriented and the coefficient of thermal expansion in the stretching direction is large and the direction perpendicular to the stretching direction is oriented and the orthogonal direction of The combined vector of the vector with the coefficient of expansion coefficient is the angle formed with the extending direction θh, the plugging portion has the direction of the extending direction and the coefficient of thermal expansion in the extending direction, and the extending direction. The combined vector of the vector with the direction orthogonal to the direction and the coefficient of thermal expansion in the orthogonal direction as the magnitude is θm as the angle formed with the stretching direction, and the difference between θh and θm is smaller than 15 degrees. It is characterized by. Here, the thermal expansion coefficient in the stretching direction and the direction orthogonal thereto corresponds to the vertical and horizontal thermal expansion coefficients.

In the above structure, the difference in the thermal expansion coefficient between the extending direction and the direction orthogonal to the extending direction is set to be less than 0.5 × 10 ⁻⁶ / ° C. in both the honeycomb structure and the plugged portion. That is, the honeycomb structure and the plugging portion are made of a material having a small vertical and horizontal thermal expansion coefficient. In addition, both the honeycomb structure and the plugging portion are set such that the difference in the thermal expansion coefficient in the stretching direction and the difference in the thermal expansion coefficient in the direction orthogonal to the stretching direction are both less than 3.5 × 10 ⁻⁶ / ° C. Has been. That is, the honeycomb structure and the plugging portion are made of materials having vertical and horizontal thermal expansion coefficients close to each other.

Further, in the above configuration, the difference between the angle θh formed by the combined vector of the longitudinal and lateral thermal expansion coefficients in the honeycomb structure and the extending direction and the angle θm formed by the combined vector of the longitudinal and lateral thermal expansion coefficients in the plugged portion. Is set to be smaller than 15 degrees. That is, the combined vector of the vertical and horizontal thermal expansion coefficients of the honeycomb structure and the plugged portions are oriented in substantially the same direction. By adopting such a configuration, even if the difference in longitudinal and lateral thermal expansion coefficients between the substances constituting the honeycomb structure and the plugging portion is within the above range, it can be more resistant to thermal shock.

  Thereby, generation | occurrence | production of the crack by the thermal shock resulting from the thermal expansion difference between a honeycomb structure and a plugging part can be suppressed by the method different from patent document 1,2. Therefore, without hindering the freedom of material selection and porosity setting of the plugged portion, it is possible to promote the accumulation of PM in the plugged portion, or to cause variation in the PM purification function between cells. I don't have to.

  In the honeycomb filter of the present invention, it is preferable that the standard deviation of the end face position on the center side of the cell in the plugged portion is 3.2% or less.

  According to this, the PM purification function becomes uniform between cells, and the stability of the purification quality as a honeycomb filter can be sufficient.

  In the honeycomb filter of the present invention, it is more preferable that the honeycomb structure has a porosity of 50 to 80% and the plugged portion has a porosity of 2 to 10%.

  Even if the honeycomb structure has a relatively high porosity, the porosity of the plugged portion is reduced, so that PM is present in the plugged portion as in the case where the porosity of the plugged portion is high. Accumulation can be suppressed, and thermal shock resistance can be prevented from being hindered during regeneration heating of the honeycomb filter.

  In the honeycomb filter of the present invention, it is preferable that the main constituent material of the plugged portion is different from the main constituent material of the honeycomb structure.

  By making the constituent materials of the honeycomb structure and the plugged portions different, the degree of freedom in selecting the material of the plugged portions can be expanded.

  In the honeycomb filter of the present invention, the main constituent material of the honeycomb structure is silicon nitride, and the main constituent material of the plugged portion includes a reaction product of a calcium oxide-containing ceramic aggregate and an inorganic binder. It can also be configured.

  According to the present invention, the occurrence of cracks due to thermal shock caused by the difference in thermal expansion between the honeycomb structure and the plugged portion, without hindering the freedom of material selection and porosity setting of the plugged portion, In addition, it is possible to suppress the PM deposition in the plugged portion without causing the variation in the PM purification function between cells.

1 is a schematic diagram of a honeycomb filter according to Embodiment 1 of the present invention. It is sectional drawing of the principal part of the honey-comb filter shown in FIG. (A) and (b) are both explanatory diagrams showing an expansion vector and an angle θ formed by the expansion vector and the axial direction. It is a schematic diagram of the honeycomb filter which concerns on Embodiment 2 of this invention. FIG. 5 is a schematic view of a honeycomb segment body constituting the honeycomb structure of the honeycomb filter shown in FIG. 4. FIG. 6 is a schematic diagram of a segment joined body in which a plurality of honeycomb segment bodies shown in FIG. 5 are joined to each other at a joined portion.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a schematic diagram of the honeycomb filter of the present embodiment. As shown in FIG. 1, the present honeycomb filter 1 includes a honeycomb structure 10, a plugging portion 13, and an outer peripheral coating layer 15.

  The honeycomb structure 10 has a cylindrical shape, and is composed of one porous ceramic fired body in which a large number of cells 11 including through holes are regularly formed along the axial direction of the honeycomb filter 1, that is, the A direction. . The honeycomb filter 1 is arranged so that the A direction, which is also the extending direction of the cells 11, is parallel to the flow of the exhaust gas.

  The cell 11 has a substantially square cross-sectional shape in the direction perpendicular to the axial direction, and is formed by being partitioned by a cell wall 12 made of a porous material. The honeycomb structure 10 has a function as a collecting member for particulate matter (hereinafter referred to as PM) contained in the exhaust gas and a function as a structure of the honeycomb filter 1.

  The plugging portion 13 plugs one end of the cell 11. Each cell 11 is sealed at either the upstream or downstream end face of the honeycomb filter 1 in the exhaust gas flow direction. The plugging is made on different end surfaces of the adjacent cells 11, and the plugging portions 13 form a checkered pattern on each end surface as shown in FIG. 1.

  The outer peripheral covering layer 15 covers the outer peripheral portion of the honeycomb structure 10. The outer periphery covering layer 15 is made of a ceramic layer, and is formed by firing an outer periphery covering material applied to the outer periphery of the honeycomb structure 10.

  In the honeycomb filter 1 having such a configuration, the exhaust gas flows from the cells 11 that are not sealed at the upstream end face, passes through the micropores of the porous cell wall 12, and passes from the adjacent cells 11. leak. At this time, PM contained in the exhaust gas is collected by the cell wall 12 when the exhaust gas passes through the fine holes of the cell wall 12. The collected PM is removed from the honeycomb filter 1 by subjecting the honeycomb filter 1 to regeneration heating treatment.

  In FIG. 1, the honeycomb structure 10 is exemplified by a columnar shape in which the cross-sectional shape in the direction perpendicular to the axial direction of the honeycomb filter 1 is circular, but the cross-sectional shape is not particularly limited. For example, it may be oval, square, rectangular, or polygonal. The optimum value of the cross-sectional size of the honeycomb filter 1 is determined by the engine displacement. The honeycomb structure 10 can be molded in advance into a desired shape using an extruder.

  The cross-sectional shape of the cell 11 is preferably substantially square, but is not necessarily limited to this, and may be other shapes. Although the thickness of the cell wall 12 is not specifically limited, For example, it is 0.2-0.4 mm. Further, the number of cells in the unit area is not particularly limited, but is, for example, 200 to 300 cpsi. Although the thickness of the outer peripheral coating layer 15 is not particularly limited, it is generally 0.3 mm to 1.0 mm.

As a material of each part in the honeycomb filter 1, a conventional existing material can be used. For example, the honeycomb structure 10 is obtained by sintering a composition containing a main constituent material constituting the honeycomb structure 10 and conventionally known sintering aids, conventionally known various binders, or reactive sintering. Can be formed. Main constituent materials include nitride ceramics such as silicon nitride, aluminum nitride, boron nitride and titanium nitride, oxide ceramics such as silicon nitride, alumina (Al ₂ O ₃ ), silica and mullite, silicon carbide, zirconium carbide, carbonized Examples thereof include carbide ceramics such as titanium, tantalum carbide, and tungsten carbide. Among these, silicon nitride is preferable from the viewpoint of strength and heat resistance. Note that silicon nitride also includes sialon in which part of silicon and nitrogen in silicon nitride is replaced with aluminum and oxygen, respectively.

  As the plugging portion 13, ceramic clay such as aluminum titanate, silicon carbide, silicon nitride, alumina, cordierite, mullite, or cement material can be used. These may be used alone or in combination. Especially, as the plugging part 13, the structure containing the reaction material of a calcium oxide containing ceramic aggregate and an inorganic binder is preferable. In order to adjust the concentration of the sealing material, a diluent such as water is used.

  The outer peripheral coating layer 15 is made of a ceramic layer, and is formed by blending an inorganic balloon, colloidal silica, or bentonite with a main raw material of a honeycomb such as silicon nitride.

In the honeycomb filter 1, a notable configuration is that the honeycomb structure 10 and the plugging portion 13 have thermal expansion coefficients satisfying the following conditions (1) to (3).
(1) The honeycomb structure 10 and the plugging portion 13 each have a difference in thermal expansion coefficient between the axial direction and the direction orthogonal thereto is less than 0.5 × 10 ⁻⁶ / ° C. That is, if the thermal expansion coefficient in the axial direction of the honeycomb structure 10 is αh and the thermal expansion coefficient in the axial axis direction orthogonal to this is αh⊥, | αh−αh⊥ |, which is the difference between αh and αh⊥, is 0. It is less than 5 × 10 ⁻⁶ / ° C. Similarly, if the thermal expansion coefficient in the axial direction of the plugged portion 13 is αm and the thermal expansion coefficient in the axial direction is αm⊥, | αm−αm⊥ |, which is the difference between αm and αm⊥, is 0.5. × 10 ⁻⁶ / ° C.
(2) In the honeycomb structure 10 and the plugging portion 13, both the difference in the thermal expansion coefficient in the stretching direction and the difference in the thermal expansion coefficient in the direction orthogonal to the stretching direction are 3.5 × 10 ⁻⁶ / It is less than ℃. That is, | αh−αm |, which is the difference between αh and αm, and | αh⊥−αm⊥ |, which is the difference between αh⊥ and αm⊥, are less than 3.5 × 10 ⁻⁶ / ° C.
(3) In the honeycomb structure 10, a composite vector of a vector whose axial direction is the direction and the axial thermal expansion coefficient is large and a vector whose axial axis direction is the direction and whose thermal expansion coefficient is the magnitude is The angle formed with the axial direction is θh, and the plugging portion 13 is a vector in which the axial direction is the direction and the axial thermal expansion coefficient is large, and the axial axial direction is the direction and the thermal expansion coefficient in the axial axial direction is the magnitude. An angle formed by the combined vector with the vector is θm, and the difference between θh and θm is smaller than 15 degrees.

FIGS. 3A and 3B are explanatory diagrams showing the combined vector included in the condition (3) and the angle θ formed by the combined vector and the axial direction. As shown in FIG. 3A, the vector X is oriented in the axial direction and has a coefficient of thermal expansion in the axial direction. The vector Y is oriented in the axial axis direction and has a coefficient of thermal expansion in the axial axis direction. An angle θ formed by an angle formed between the vector X and the vector Y and a combined vector Z formed with the axial direction. Hereinafter, the combined vector is referred to as an expansion vector.

  Further, as shown in FIG. 3B, the difference between θh and θm is the difference between the angles θh and θm formed by the expansion vectors Zh and Zm of the honeycomb structure 10 and the plugging portions 13 and the axial direction. It is.

  The material of the honeycomb structure 10 and the plugging portion 13 are adjusted so as to satisfy the above-described conditions of the thermal expansion coefficient in the axial direction and axial direction. The thermal expansion coefficients in the axial direction and the axial heel direction correspond to vertical and horizontal thermal expansion coefficients.

Under the condition (1), each of the honeycomb structure 10 and the plugging portion 13 is made of a material having a small vertical and horizontal thermal expansion coefficient. In addition, the honeycomb structure 10 and the plugging portions 13 are made of materials having vertical and horizontal thermal expansion coefficients close to each other under the condition (2). Further, under the condition (3), the expansion vector Zh of the honeycomb structure 10 and the expansion vector Zm of the plugging portion 13 are directed in substantially the same direction, so that the honeycomb structure 10 and the plugging portion 13 are Even if there is a difference in the vertical and horizontal thermal expansion coefficients between the constituent materials (difference within the above range), it can be made stronger against thermal shock.

  Thereby, generation | occurrence | production of the crack by the thermal shock resulting from the thermal expansion difference between the honeycomb structure 10 and the plugging part 13 can be suppressed with the method different from patent document 1,2. Therefore, without obstructing the freedom of material selection and porosity setting of the plugging portion 13, the PM deposition in the plugging portion 13 is promoted, and the PM purification function varies among the cells 11. It does not cause it. This will be described in more detail.

  In the present honeycomb filter 1, as in Patent Document 1, it is possible to prevent cracks from occurring at the boundary portion without making the plugged portion thickness uneven. As a result, the axial length of the cells 11 forming the wall flow filter function can be made the same in the plurality of cells 11 constituting the honeycomb filter 1.

  More specifically, in the honeycomb filter 1, it is preferable that the standard deviation of the end face position on the central portion side of the cell 11 in the plugged portion 13 is 3.2% or less. By adopting such a configuration, the PM purification function becomes uniform between the cells 11 and the honeycomb filter 1 can have sufficient purification quality stability.

  Further, in the honeycomb filter 1, the main constituent material can be made different between the honeycomb structure 10 and the plugging portion 13, so that the degree of freedom in selecting the material of the plugging portion 13 can be expanded.

  Further, in the present honeycomb filter 1, as in Patent Document 2, it is possible to prevent cracks from occurring at the boundary even if the porosity of the plugged portion is not regulated by the porosity of the honeycomb structure. As a result, the porosity of the plugged portion 13 can be freely set.

  More specifically, in the honeycomb filter 1 of the present invention, the porosity of the honeycomb structure 10 is preferably 50 to 80%, and the porosity of the plugging portion 13 is preferably 2 to 10%. The porosity of the honeycomb structure 10 is more preferably 50 to 70%. The porosity of the plugged portion 13 is more preferably 2 to 8.5%, and further preferably 5 to 8%.

  Even if the honeycomb structure 10 has a relatively high porosity of 50% or more, the plugging portion 13 has a porosity of 10% or less (preferably 8.5% or less, more preferably 8% or less). Therefore, it is possible to suppress PM from being deposited on the plugged portion 13 as in the case where the porosity of the plugged portion 13 is high, and the thermal shock resistance is improved during regeneration heating of the honeycomb filter 1. Inhibition can be suppressed.

  Further, in the honeycomb filter 1, the main constituent material of the honeycomb structure 10 is silicon nitride, and the main constituent material of the plugging portion 13 is a reaction product of a calcium oxide-containing ceramic aggregate and an inorganic binder. It is more preferable to have a configuration including

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those used in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The honeycomb filter 1 of the first embodiment is a so-called integral type in which the honeycomb structure 10 is formed of one porous ceramic fired body. On the other hand, the honeycomb filter of the second embodiment is a so-called split type in which a honeycomb segment body is formed in a prismatic shape, and each honeycomb segment body, which is a porous ceramic fired body, is bonded through a joint. It is.

  FIG. 4 is a schematic diagram of the honeycomb filter of the present embodiment. As shown in FIG. 4, the honeycomb filter 20 includes a plurality of honeycomb segment bodies 21 each having a large number of cells 11 stacked in two directions orthogonal to the A direction that is the extending direction of the cells 11, and the outer surfaces are joined to each other. The honeycomb structure 25 formed by joining at the portion 23 is provided.

  FIG. 5 is a schematic diagram of one honeycomb segment body 21. As shown in FIG. 5, the honeycomb segment body 21 has a prismatic shape having a square cross-sectional shape in a direction perpendicular to the axial direction of the honeycomb filter 20. A plurality of honeycomb segment bodies 21 are combined to form one honeycomb structure 25. Therefore, it has the same configuration as the honeycomb structure 10 of the first embodiment except that the shape of the cross section perpendicular to the axial direction is smaller than that of the honeycomb structure 10 of the first embodiment.

  The joining portion 23 joins the outer surfaces of the honeycomb segment bodies 21 and is formed by curing a joining material obtained by mixing materials constituting the joining portion 23.

Examples of the bonding material forming the bonding portion 23 include ceramics such as cordierite, aluminum titanate, alumina (Al ₂ O ₃ ), forsterite, zirconia (ZrO ₂ ), and magnesium oxide (MgO). .

  The thickness of the joint portion 23 is a conventionally known thickness, for example, 0.5 to 10 mm, preferably 1 to 5 mm, and more preferably 1 to 3 mm.

  FIG. 6 is a schematic diagram of a segment bonded body in which a plurality of honeycomb segment bodies are bonded to each other at a bonded portion. The segment joined body 27 is ground so that the cross-sectional shape in the direction perpendicular to the axial direction is circular along the assumed processing curved surface 29 indicated by a broken line in the drawing. Thereby, it is processed into a cylindrical shape, and the outer peripheral covering material is applied to the outer peripheral surface thereof to form the outer peripheral covering layer 15.

  Also in the present honeycomb filter 20, each honeycomb segment body 21 and the plugging portion 13 satisfy the conditions (1) to (3), and the plugging portion 13 is formed in the honeycomb structure 25. The condition of the standard deviation of the end face position described above is satisfied.

  Examples of the honeycomb filter 1 according to Embodiment 1 will be described.

Example 1
23% by weight of metal silicon (manufactured by Yamaishi Metal), 22% by weight of β-type silicon nitride (manufactured by Denki Kagaku Kogyo), 16% by weight of pore-forming agent (raw material: phenolic resin) (manufactured by Air Water), binder for extrusion molding (raw material: Methyl cellulose) 16% by weight (manufactured by Shin-Etsu Chemical Co., Ltd.) and a raw material consisting of water were mixed and kneaded, and a honeycomb-shaped cylindrical body having a diameter of 144 × 150 mm and a cell pitch of 1.7 mm was formed by an extruder. After degreasing, reaction sintering was performed in nitrogen to produce a honeycomb structure 10 of Example 1. The firing temperature was 1000 to 1450 ° C. for the first firing and 1700 to 1800 ° C. for the second firing.

  The porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured. The porosity was measured using an Archimedes density meter, and the thermal expansion coefficients αh and αh⊥ were measured using a differential thermal expansion meter.

The measurement results are shown below.
Porosity: 60%
Axial thermal expansion coefficient αh: 3.00 × 10 ⁻⁶ / ° C.
Thermal expansion coefficient αhα in the axial axis direction: 2.94 × 10 ^-6 / ° C
Al ₂ O ₃ (manufactured by Showa Denko), SiO ₂ (manufactured by Kinsei Matec), CaO, colloidal silica (manufactured by Nissan Chemical Industries) are mixed in the honeycomb structure 10 with the composition shown in Table 1, and plugged. The sealing material used as the part 13 was created. The prepared sealing material was filled to a depth of 5 mm from the end face in the axial direction of the honeycomb structure 10 and dried to create a plugged portion 13.

  Subsequently, an inorganic balloon (manufactured by Denki Kagaku Kogyo), silicon nitride particles (manufactured by Denki Kagaku Kogyo), colloidal silica (manufactured by Nissan Kagaku Kogyo), water, binder (raw materials: bentonite, manufactured by Hojun) are mixed, and the outer peripheral coating layer The outer periphery covering material used as 15 was created. The outer peripheral coating material 15 was applied to the outer surface of the honeycomb structure 10 with a thickness of 0.3 to 1 mm, and then fired at a temperature of 550 to 750 ° C., thereby forming the outer peripheral coating layer 15. 1 honeycomb filter was obtained.

  In addition, a sample for measuring physical properties was created under the same conditions as those for creating the plugged portion 13 in the honeycomb filter of Example 1, and the porosity and thermal expansion coefficient of the plugged portion 13 were measured in the same manner as described above. Measured by the method.

  Further, in the prepared honeycomb filter of Example 1, the quasi-deviation of the end face position on the central portion side of the cell 11 in the plugged portion 13 was obtained. As for the standard deviation of the end face position, the honeycomb was cut in parallel to the axial direction, the plugged portion was photographed with a laser microscope, and the dimensions were measured.

The measurement results are shown below.
Porosity: 8.9%
Axial thermal expansion coefficient αm: 5.5 × 10 ⁻⁶ / ° C.
Thermal expansion coefficient αmα in the axial axis direction: 5.6 × 10 ^-6 / ° C
Standard deviation of end face position: 2.8%
Also, | αh−αh⊥ |, which is a difference between αh and αh し た, and | αm−αm⊥ |, which is a difference between αm and αm⊥, and a difference between αh and αm, which are calculated from the measurement results | αh The results of calculating −αm |, | αhα−αm⊥ |, which is the difference between αh⊥ and αm⊥, and | θh−θm |, which is the difference between θh and θm, are shown below.
| Αh−αh⊥ |: 0.06 × 10 ⁻⁶ / ° C.
| Αm−αm∥: 0.1 × 10 ⁻⁶ / ° C.
| Αh−αm |: 2.50 × 10 ⁻⁶ / ° C.
| Αh⊥−αm⊥ |: 2.66 × 10 ⁻⁶ / ° C.
| Θh−θm |: 2 degrees (Example 2)
Silicon carbide particles 67% by weight (manufactured by Yakushima Denko), silicon nitride fine particles 17% by weight (manufactured by Denki Kagaku Kogyo), pore former (phenol resin 8% by weight (manufactured by Air Water)) binder for extrusion molding (raw material: methylcellulose) 8% % (Manufactured by Shin-Etsu Chemical Co., Ltd.) and raw materials consisting of water were mixed and kneaded, and a honeycomb-shaped cylindrical body having a diameter of 144 mm × 150 mm and a cell pitch of 1.7 mm was formed by an extruder, and after degreasing, 1350 to 1450 ° C. in an argon stream. The honeycomb structure 10 was prepared by sintering.

  The porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured by the same method as described above. Thereafter, the plugging portion 13 was created in the same manner as in Example 1 except that the formulation described in Table 1 was changed, and the outer peripheral coating layer 15 was created in the same manner as in Example 1. 2 honeycomb filters were obtained. In the obtained honeycomb filter, the quasi-deviation of the end face position on the central part side of the cell 11 in the plugged portion 13 was obtained in the same manner as in Example 1. In addition, a sample for measuring physical properties of the plugged portion 13 was created under the same conditions as the honeycomb filter of Example 2, and the porosity and thermal expansion coefficient of the plugged portion 13 were also measured. Table 1 also shows the measured results and the difference in thermal expansion coefficient calculated from the results.

(Example 3)
26% by weight of titanium oxide powder (manufactured by Sakai Chemical Industry), 50% by weight of alumina powder (manufactured by Showa Denko), 15% by weight of pore-forming agent (raw material: phenol resin) (manufactured by Air Water), binder for extrusion molding (raw material: methylcellulose) ) 8% by weight (manufactured by Shin-Etsu Chemical Co., Ltd.) and a raw material consisting of water were mixed and kneaded, and a honeycomb cylindrical body having a diameter of 144 × 150 mm and a cell pitch of 1.7 mm was formed by an extruder. After degreasing, sintering was performed at 1350 to 1450 ° C. in the atmosphere to prepare the honeycomb structure 10.

  The porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured by the same method as described above. Thereafter, the plugging portion 13 was created in the same manner as in Example 1 except that the formulation described in Table 1 was changed, and the outer peripheral coating layer 15 was created in the same manner as in Example 1. 3 honeycomb filters were obtained. In the obtained honeycomb filter, the quasi-deviation of the end face position on the central part side of the cell 11 in the plugged portion 13 was obtained in the same manner as in Example 1. In addition, a sample for measuring physical properties of the plugged portion 13 was created under the same conditions as the honeycomb filter of Example 3, and the porosity and thermal expansion coefficient of the plugged portion 13 were also measured. Table 1 also shows the measured results and the difference in thermal expansion coefficient calculated from the results.

Example 4
A honeycomb structure 10 was prepared in the same manner as in Example 1, and after the porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured, plugging portions 13 were formed in the same manner as in Example 1. Created. At this time, it was created so that the position of the end surface on the central side of the cell 11 was more varied than that of Example 1. Then, the outer periphery coating layer 15 was produced like Example 1, and the honeycomb filter of Example 4 was obtained. In the obtained honeycomb filter, the quasi-deviation of the end face position on the center part side of the cell 11 in the plugged portion 13 was obtained. In addition, a sample for measuring physical properties of the plugged portion 13 was created under the same conditions as the honeycomb filter of Example 4, and the porosity and thermal expansion coefficient of the plugged portion 13 were also measured. Table 1 also shows the measured results and the difference in thermal expansion coefficient calculated from the results.

(Comparative Example 1)
Magnesium silicate 28% by weight (manufactured by Kinsei Matec), aluminum hydroxide 34% by weight (manufactured by Showa Denko), silica 15% by weight (Kinsei Matech) pore former (raw material: phenolic resin) 20% by weight (manufactured by Air Water), extrusion A formed binder (raw material: methylcellulose) 8% by weight (manufactured by Shin-Etsu Chemical Co., Ltd.) and a raw material consisting of water were mixed and kneaded, and a honeycomb-shaped cylindrical body having a diameter of 144 × 150 mm and a cell pitch of 1.7 mm was formed by an extruder. After degreasing, sintering was performed at 1350 to 1450 ° C. in the atmosphere to prepare the honeycomb structure 10.

  The porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured by the same method as described above. Then, except having changed into the mixing | blending described in Table 1, the plugging part 13 was created like Example 1, and also the outer periphery coating layer 15 was created like Example 1, and a comparative example 1 honeycomb filter was obtained. In the obtained honeycomb filter, the quasi-deviation of the end face position on the central part side of the cell 11 in the plugged portion 13 was obtained in the same manner as in Example 1. In addition, a sample for measuring physical properties of the plugged portion 13 was created under the same conditions as the honeycomb filter of Comparative Example 1, and the porosity and thermal expansion coefficient of the plugged portion 13 were also measured. Table 1 also shows the measured results and the difference in thermal expansion coefficient calculated from the results.

(Comparative Example 2)
A honeycomb structure 10 was prepared in the same manner as in Comparative Example 1, and the porosity and thermal expansion coefficient of the obtained honeycomb structure 10 were measured by the same method as described above. Then, except having changed into the mixing | blending described in Table 1, the plugging part 13 was created like Example 1, and also the outer periphery coating layer 15 was created like Example 1, and a comparative example 2 honeycomb filters were obtained. In the obtained honeycomb filter, the quasi-deviation of the end face position on the central part side of the cell 11 in the plugged portion 13 was obtained in the same manner as in Example 1. In addition, a sample for measuring physical properties of the plugged portion 13 was created under the same conditions as the honeycomb filter of Comparative Example 2, and the porosity and thermal expansion coefficient of the plugged portion 13 were also measured. Table 1 also shows the measured results and the difference in thermal expansion coefficient calculated from the results.

  The honeycomb filters of Examples 1 to 4 and Comparative Examples 1 and 2 thus produced were subjected to a thermal shock test that was repeated 10 times after being held in a furnace at 600 ° C. for 2 hours and then air-cooled, and plugged. It was confirmed whether or not cracks occurred in the portion 13. Table 1 also shows the confirmation results.

  As shown in Table 1, with respect to the honeycomb filters of Examples 1 to 4 in which the porosity, the axial direction, and the axial expansion coefficient in the plugged portion 13 satisfy the above-described conditions, After the test, no cracks occurred in the plugged portion 13. On the other hand, in the honeycomb filters of Comparative Examples 1 and 2 that did not satisfy the above conditions, cracks occurred in the plugged portions 13 after the test.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be suitably used as an exhaust gas purification filter for collecting particulate matter contained in exhaust gas of a diesel engine.

DESCRIPTION OF SYMBOLS 1 Honeycomb filter 10 Honeycomb structure 11 Cell 12 Cell wall 13 Plugging part 15 Outer peripheral coating layer 20 Honeycomb filter 21 Honeycomb segment body 23 Joint part 25 Honeycomb structure 27 Segment joined body 29 Process assumption curved surface

Claims (5)

A honeycomb structure comprising a fired body having a plurality of cells extending in one direction formed by being partitioned by cell walls, wherein one end portion of the plurality of cells in the extending direction is plugged at a plugging portion. A honeycomb filter that is stopped,
The honeycomb structure and the plugging portion each have a difference in thermal expansion coefficient between the stretching direction and a direction perpendicular to the stretching direction of less than 0.5 × 10 ⁻⁶ / ° C., and Both the difference in thermal expansion coefficient and the difference in thermal expansion coefficient in the direction orthogonal to the stretching direction are less than 3.5 × 10 ⁻⁶ / ° C.,
Further, in the honeycomb structure, a vector in which the extending direction is directed and a coefficient of thermal expansion in the extending direction is increased, and a vector in which a direction orthogonal to the extending direction is directed and the coefficient of thermal expansion in the orthogonal direction is increased. Is the angle formed with the stretching direction θh, and the plugging portion faces the stretching direction and the coefficient of thermal expansion in the stretching direction and the direction orthogonal to the stretching direction. The honeycomb filter is characterized in that a combined vector of a vector having a coefficient of thermal expansion in a direction orthogonal to the above is θm as an angle formed with the drawing direction, and a difference between θh and θm is smaller than 15 degrees .   2. The honeycomb filter according to claim 1, wherein a standard deviation of an end face position of the plugged portion on the center side of the cell is 3.2% or less.   The honeycomb filter according to claim 1 or 2, wherein the honeycomb structure has a porosity of 50 to 80%, and the plugged portion has a porosity of 2 to 10%.   The honeycomb filter according to any one of claims 1 to 3, wherein a main constituent material of the plugged portion is different from a main constituent material of the honeycomb structure.   The main constituent material of the honeycomb structure is silicon nitride, and the main constituent material of the plugged portion includes a reaction product of a calcium oxide-containing ceramic aggregate and an inorganic binder. 5. The honeycomb filter according to any one of 4 above.

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