Segmental joints

Abstract

To provide a segment joint with reduced bending. [Solution] A segment bonded body having a plurality of honeycomb structure segments in which at least one planar side surface is bonded to each other via a bonding material, wherein the maximum bending amount of each of the at least one planar side surface used to bond adjacent honeycomb structure segments is Smax (unit: mm), and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is L (unit: mm), and the segment bonded body satisfies Smax / L≦0.010.

Description

[Technical Field]

[0001] The present invention relates to a segment bonded assembly having a plurality of honeycomb structure segments whose side surfaces are bonded to each other via a bonding material. [Background technology]

[0002] Particulate matter (PM) in exhaust gases emitted from internal combustion engines such as diesel and gasoline engines contains soot. Soot is harmful to humans, so its emission is regulated. Currently, to comply with exhaust gas regulations, porous ceramic filters with a columnar honeycomb structure, such as DPFs and GPFs, are widely used, which filter out PM such as soot by passing exhaust gas through porous ceramic partition walls.

[0003] To continue using such filters for an extended period of time, the filters must be regenerated. That is, to eliminate the increase in pressure loss caused by PM that accumulates inside the filter over time, the PM that has accumulated inside the filter must be burned and removed. This filter regeneration process generates large thermal stresses, which can cause defects such as cracks and breaks in the filter.

[0004] In response to the demand for improved thermal shock resistance against such thermal stress, a filter has been proposed that has a segment structure in which the sides of multiple honeycomb structure segments are joined together with a bonding material to form a segment bonded body, thereby providing the function of dispersing and mitigating thermal stress, and attempts have been made to further improve its thermal shock resistance.

[0005] However, in recent years, there has been an increasing demand for larger filters, which increases the thermal stress generated during regeneration. To prevent the defects described above, there is a strong demand for improved thermal shock resistance. However, because filters are made of porous ceramics, they are prone to bending when they are made larger and longer. Known methods for preventing filter bending include adding a water-absorbent resin and a pore-forming material to the clay (Patent Document 1) and arranging a specified back plate on the inlet side of the die when extruding the raw material (Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4627498 [Patent Document 2] Japanese Patent Application Publication No. 2023-149427 Summary of the Invention [Problem to be solved by the invention]

[0007] The methods described in Patent Documents 1 and 2 contribute to reducing the amount of bending of honeycomb molded bodies before firing. However, because they do not take into account bending during firing, there is still room for improvement in terms of reducing bending in fired products. Furthermore, the methods described in Patent Documents 1 and 2 lack sufficient consideration of reducing bending in the bonded segment body, which is the final product. In other words, the consideration is insufficient because the bonded segment body is composed of a plurality of honeycomb structure segments. The development of technology to reduce bending in the bonded segment body, which is the final product, is thought to contribute to improving compressive strength in addition to thermal shock resistance, and would be particularly beneficial in the field of filters, where products are becoming larger.

[0008] In view of the above circumstances, an object of one embodiment of the present invention is to provide a segment joint in which bending is suppressed. [Means for solving the problem]

[0009] [Aspect 1] A segment conjugate, The segment bonded body has a plurality of honeycomb structure segments, at least one of which has a flat side surface bonded to another via a bonding material, Each of the plurality of honeycomb structure segments has a first segment bottom surface, a second segment bottom surface, and at least one planar side surface connecting the first segment bottom surface and the second segment bottom surface, and also has porous ceramic partition walls that define a plurality of cells extending from the first segment bottom surface to the second segment bottom surface, When the maximum bending amount of each of the at least one planar side surface used to join adjacent honeycomb structure segments is Smax (unit: mm), and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is L (unit: mm), each of the plurality of honeycomb structure segments satisfies Smax / L≦0.010. Segmental junction. [Aspect 2] 2. The bonded segment assembly according to embodiment 1, wherein each of the plurality of honeycomb structure segments has an Smax of 2.0 mm or less. [Aspect 3] 2. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has an Smax of 1.0 mm or less. [Aspect 4] 3. The bonded segment assembly according to embodiment 1 or 2, wherein each of the plurality of honeycomb structure segments has an L of 50 to 350 mm. [Aspect 5] the segment joint has a cylindrical outer shape with an outer peripheral side surface, a first circular bottom surface, and a second circular bottom surface; A segment joined body according to any one of aspects 1 to 4, wherein R1, R2, and R3 are radial distances from the central axis to the outer peripheral side surface at a height position 10 mm inward from the first circular bottom surface in the direction of extension of the central axis, a height position 10 mm inward from the second circular bottom surface in the direction of extension of the central axis, and a height position at the midpoint of the central axis; and |R3-(R1+R2) / 2| in the radial direction at which the absolute value of |R3-(R1+R2) / 2| is maximum is defined as Fmax, and Fmax is 2.0 mm or less. [Aspect 6] 6. The segment joint body according to embodiment 5, wherein Fmax is 1.0 mm or less. [Aspect 7] 7. The joined segment assembly according to any one of aspects 1 to 6, having an isostatic fracture strength of 1.0 MPa or more. [Aspect 8] The bonded segments according to any one of aspects 1 to 7, wherein the bonded segments are heated in an electric furnace at a set temperature for 60 minutes (if the volume of the bonded segments is 5 L or less) or for 120 minutes (if the volume of the bonded segments is more than 5 L), then removed from the electric furnace, allowed to cool to room temperature, and visually inspected to determine whether or not a crack of 3 mm or longer has occurred in the bonded segments; this step is repeated starting from an initial temperature of 200°C and increasing the set temperature by 50°C increments until a crack is observed; and the set temperature at which a crack is observed is 250°C or higher. [Aspect 9] 9. The segment bonded assembly according to any one of aspects 1 to 8, wherein each of the plurality of honeycomb structure segments has a thermal conductivity of 3 W / (m·K) or more at 50° C. as measured by a disc heat flow meter method in accordance with ASTM E1530. [Aspect 10] Each of the honeycomb structure segments has an average linear expansion coefficient of 5.5×10 when measured according to JIS R1618:2002 at temperatures ranging from 40°C to 800°C. -6 10. The segment-joined structure according to any one of aspects 1 to 9, wherein the tensile strength is 1 / K or less. [Aspect 11] 11. The bonded segment assembly according to any one of aspects 1 to 10, wherein each of the plurality of honeycomb structure segments has a porosity of 70% or less. [Aspect 12] 12. The bonded segment assembly according to embodiment 11, wherein each of the honeycomb structure segments has a porosity of 30% or more and 70% or less. [Aspect 13] 13. The bonded segment assembly according to any one of aspects 1 to 12, wherein each of the plurality of honeycomb structure segments contains 70 parts by mass or more of silicon carbide per 100 parts by mass of the total of silicon carbide and silicon. [Aspect 14] 14. The segment bonded assembly according to any one of claims 1 to 13, wherein each of the honeycomb structure segments contains silicon oxide, strontium oxide, and aluminum oxide, and the aluminum oxide content is 1.0% or more based on the total mass of the silicon oxide, strontium oxide, and aluminum oxide. [Aspect 15] 15. The segment bonded assembly according to any one of aspects 1 to 14, wherein each of the plurality of honeycomb structure segments contains 0.2 to 2.5 parts by mass of aluminum oxide per 100 parts by mass of the total of silicon carbide and silicon. [Aspect 16] A segment conjugate, the segment bonded body has a plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via a bonding material, Each of the plurality of rectangular parallelepiped honeycomb structure segments has a first segment side surface, a second segment side surface, a third segment side surface, a fourth segment side surface, a first segment bottom surface, and a second segment bottom surface, and also has porous ceramic partition walls that define a plurality of cells extending from the first segment bottom surface to the second segment bottom surface, In each of the plurality of rectangular parallelepiped honeycomb structure segments, when the maximum amount of bending of the first segment side surface, the second segment side surface, the third segment side surface, and the fourth segment side surface used to join adjacent honeycomb structure segments is Smax (unit: mm), and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is L (unit: mm), the relationship Smax / L≦0.010 is satisfied. Segmental junction. [Aspect 17] A segment bonded body according to embodiment 16, wherein among the plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via bonding material, there are at least two rectangular parallelepiped honeycomb structure segments whose side surfaces have the largest bending amount and whose orientations are the same. [Aspect 18] A segment bonded assembly according to embodiment 17, wherein at least 30% of the total number of the plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via bonding material have the same orientation of the side surface having the largest amount of bending. [Aspect 19] A segment bonded assembly according to embodiment 17, wherein the orientation of the side having the maximum bending amount is consistent for all of the plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via bonding material. [Effects of the Invention]

[0010] According to one embodiment of the present invention, a segment assembly with reduced bending is provided. Because the segment assembly with reduced bending has significantly improved thermal shock resistance and compressive strength, it is particularly suitable for use in filters such as DPFs and GPFs, which are becoming larger in size. [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 2 is a schematic bottom view of a segment bonded assembly according to one embodiment of the present invention. [Figure 1B]FIG. 2 is a schematic side view of a segment joint according to one embodiment of the present invention. [Figure 2] 1 is a schematic perspective view of a honeycomb structure segment constituting a segment bonded assembly according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view of a honeycomb structure segment constituting a segment bonded assembly according to one embodiment of the present invention, observed from a cross section parallel to the cell extension direction. [Figure 4] A schematic diagram is shown to explain how to measure R1, R2, and R3 for a segment joint having a cylindrical outer shape. [Figure 5] 1 is a schematic diagram illustrating a method for measuring the amount of bending of a honeycomb structure segment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, embodiments of the present invention will be described in detail with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes and improvements may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0013] (1. Structure of the Segment Joint) A segment bonded assembly according to one embodiment of the present invention can be used, for example, as a filter such as a diesel particulate filter (DPF) or a gasoline particulate filter (GPF) that is installed in an exhaust gas line from a combustion device, typically an engine mounted on a vehicle, to collect soot. The filter can be installed, for example, in an exhaust pipe. A shock-absorbing mat can be interposed between the inner surface of the exhaust pipe and the filter to hold the filter in the exhaust pipe.

[0014] FIG. 1A shows a schematic bottom view of a bonded segment assembly 10 according to one embodiment of the present invention. FIG. 1B shows a schematic side view of the bonded segment assembly 10 according to one embodiment of the present invention. The bonded segment assembly 10 has a first bottom surface 104 serving as an exhaust gas inlet and a second bottom surface 106 serving as an exhaust gas outlet. Exhaust gas flowing in from the first bottom surface 104 is purified as it passes through the bonded segment assembly 10 and is discharged from the second bottom surface 106. The bonded segment assembly 10 has a structure in which the flat side surfaces 102 of multiple honeycomb structure segments 100 are bonded to each other via a bonding material 107. Bonding multiple honeycomb structure segments 100 to form the bonded segment assembly 10 can improve thermal shock resistance. The bonded segment assembly 10 can also have an outer peripheral wall 103 formed by grinding the outer periphery to a desired shape (e.g., cylindrical), applying a coating material to the outer peripheral side surface, and then drying and heat treating the coating material.

[0015] In one embodiment, the plurality of honeycomb structure segments 100 constituting the joined segment assembly 10 include a plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces 102 are bonded to each other via bonding materials 107. The number of rectangular parallelepiped honeycomb structure segments included in the joined segment assembly 10 is not limited, but can be, for example, 4 to 100, typically 9 to 81, and more typically 16 to 64. Furthermore, the proportion of the rectangular parallelepiped honeycomb structure segments among the honeycomb structure segments included in the joined segment assembly 10 is not limited, but can be, for example, 0 to 60%, typically 10 to 55%, and more typically 25 to 50%.

[0016] (2. Characteristics of Segment Joints) Below, some characteristics that can be exhibited by a segment joint according to one embodiment of the present invention will be described. [2-1. Isostatic fracture strength] One measure of the compressive strength of a segment assembly is its isostatic fracture strength. To measure the isostatic fracture strength of a segment assembly, the assembly is submerged in water in a pressure vessel and the water pressure is gradually increased to apply isotropic pressure to the segment assembly. As the water pressure inside the pressure vessel gradually increases, fractures eventually occur in the partition walls and outer walls of the segment assembly. The pressure value (fracture strength) at which fracture occurs is the isostatic fracture strength. Isostatic fracture strength is measured based on the automotive standard (JASO M505-87) issued by the Japan Automobile Engineering Society.

[0017] For application as an automotive exhaust gas filter and / or catalyst carrier, it is desirable for the isostatic fracture strength of the bonded segment body to be high. The bonded segment body according to one embodiment of the present invention can exhibit an isostatic fracture strength of 1.0 MPa or more. The bonded segment body more preferably exhibits an isostatic fracture strength of 2.0 MPa or more, and even more preferably 5.0 MPa or more. There is no particular upper limit set for the isostatic fracture strength of the bonded segment body, but in consideration of production costs, it is usually 20 MPa or less, typically 15 MPa or less, and more typically 10 MPa or less. Therefore, the bonded segment body according to one embodiment of the present invention can exhibit an isostatic fracture strength of, for example, 1.0 to 20 MPa, preferably 2.0 to 15 MPa, and more preferably 5.0 to 10 MPa.

[0018] [2-2. Amount of bending] In one embodiment, the segmented joint 10 has a cylindrical outer shape with an outer peripheral side surface, a first circular bottom surface, and a second circular bottom surface. In this case, the outer peripheral side surface of the segmented joint 10 corresponds to the outer surface of the outer peripheral wall 103. The first circular bottom surface corresponds to the first bottom surface 104, and the second circular bottom surface corresponds to the second bottom surface 106. Let C be the line segment connecting the center of gravity O1 of the first bottom surface 104 and the center of gravity O2 of the second bottom surface 106. Let R1, R2, and R3 be the radial distances from the central axis C to the outer surface of the outer peripheral wall 103 at a height position 10 mm inward from the first bottom surface 104 in the direction of extension of the central axis C, a height position 10 mm inward from the second bottom surface 106 in the direction of extension of the central axis C, and a height position midpoint of the central axis C. If Fmax is defined as |R3-(R1+R2) / 2| in the radial direction where the absolute value of |R3-(R1+R2) / 2| is maximum, then an Fmax of 2.0 mm or less can be exhibited (see FIG. 4). It can be said that a smaller Fmax indicates a segment joint 10 with reduced bending.

[0019] A bonded segment assembly according to one embodiment of the present invention can preferably exhibit an Fmax of 1.0 mm or less, and more preferably an Fmax of 0.8 mm or less. While there is no particular lower limit for Fmax, it is usually 0.05 mm or more, typically 0.1 mm or more, and more typically 0.15 mm or more. Therefore, a bonded segment assembly according to one embodiment of the present invention can exhibit an Fmax of, for example, 0.05 to 2.0 mm, preferably 0.1 to 1.0 mm, and more preferably 0.15 to 0.8 mm.

[0020] Fmax is given as the maximum value when the absolute value of |R3 - (R1 + R2) / 2| is measured at 3,000 equally spaced points around the entire circumference of the segment joint using a laser displacement meter. In the examples, a Micro-Epsilon ILD2200-200 laser displacement meter was used.

[0021] 4 is a schematic diagram illustrating a method for measuring Fmax using a laser displacement meter 122. First, the segment assembly 10 to be measured is placed on a turntable 121 installed on a horizontal surface, with the first bottom surface 104 or the second bottom surface 106 facing downward. When placing the segment assembly 10 on the turntable 121, the distance between the center of gravity O1 of the first bottom surface 104 or the center of gravity O2 of the second bottom surface 106 and the axis of rotation of the turntable 121 does not necessarily have to be zero; even if they are separated, R1, R2, and R3 can be calculated geometrically, and may even be calculated automatically depending on the displacement meter.

[0022] The turntable 121 is configured to be rotatable at a predetermined rotation speed around a rotation axis extending in the vertical direction by a driving means such as a servo motor. The servo motor can be equipped with an encoder for detecting the amount of displacement, such as the rotation angle, of the turntable 121. The laser displacement meter 122 is attached to a support 126 and is configured to be movable in the vertical direction by a driving means such as a motor.

[0023] Next, the height and orientation of the laser displacement meter 122 are adjusted to conditions appropriate for measuring either R1, R2, or R3. Then, while irradiating the surface of the outer peripheral wall 103 with the laser 124, R1, R2, or R3 is measured at 3,000 equally spaced points while the turntable 121 rotates once. This measurement allows the change in R1, R2, or R3 of the segment assembly 10 over one circumference to be measured. The change in R1, R2, or R3 over one circumference can be stored in a computer memory or the like in association with the rotation angle θ of the turntable 121. This makes it possible to associate R1, R2, or R3 with a specific radial direction on the surface of the outer peripheral wall 103. Similar measurements are performed by changing the height of the laser displacement meter 122 to measure R1, R2, and R3, and Fmax is calculated based on the absolute value of |R3-(R1+R2) / 2| in the same radial direction. The direction of laser irradiation may be the normal direction to the surface of the outer wall 103, but even if it is in another direction, R1, R2, or R3 can be calculated geometrically, and can also be calculated automatically depending on the displacement meter.

[0024] [2-3.ESP crack temperature] When an electric furnace spalling (E-sp) test is performed on an assembled segment assembly according to one embodiment of the present invention under the following conditions, the set temperature at which cracks can be observed is 250°C or higher, preferably 450°C or higher, and typically 250°C to 400°C. The electric furnace spalling test involves heating the assembled segment assembly in an electric furnace at the set temperature for 60 minutes (if the volume of the assembled segment assembly is 5 L or less) or 120 minutes (if the volume of the assembled segment assembly is greater than 5 L), removing it from the electric furnace, allowing it to cool to room temperature, and visually inspecting the assembled segment assembly for the presence of cracks 3 mm or longer. This process is repeated, starting from an initial temperature of 200°C and increasing the set temperature by 50°C increments, until cracks are observed, and the set temperature at which cracks are observed is measured. The volume of the assembled segment assembly is calculated based on the external dimensions of the assembled segment assembly (e.g., base area x total length).

[0025] (3. Composition of honeycomb structure segments) Fig. 2 shows a schematic perspective view of a honeycomb structure segment 100 constituting a bonded segment assembly according to one embodiment of the present invention. Fig. 3 shows a schematic cross-sectional view of the honeycomb structure segment 100 constituting a bonded segment assembly according to one embodiment of the present invention, observed in a cross section parallel to the cell extension direction.

[0026] In one embodiment, the honeycomb structure segment 100 has a first segment bottom surface 104S, a second segment bottom surface 106S, and at least one flat side surface 102 connecting the first segment bottom surface 104S and the second segment bottom surface 106S. When the honeycomb structure segment 100 is observed from the side of the first segment bottom surface 104S or the second segment bottom surface 106S, the at least one flat side surface 102 typically extends linearly, and two adjacent flat side surfaces 102 typically extend linearly from a common vertex in directions perpendicular to each other. The honeycomb structure segment 100 shown in FIG. 2 has an overall rectangular parallelepiped shape, and the outer surface of the outer peripheral side wall 113 is composed of a first segment side surface 102A, a second segment side surface 102B, a third segment side surface 102C, and a fourth segment side surface 102D.

[0027] In one embodiment, the honeycomb structure segment 100 has an outer peripheral side wall 113 and a porous ceramic partition wall 112 arranged inside the outer peripheral side wall 113, which partitions a plurality of cells 108, 110 extending in parallel from the first segment bottom surface 104S to the second segment bottom surface 106S.

[0028] Each cell 108, 110 may penetrate from the first segment bottom surface 104S to the second segment bottom surface 106S by opening both the first segment bottom surface 104S and the second segment bottom surface 106S. However, to improve PM collection performance, the honeycomb structure segment 100 preferably has a plurality of first cells 108 extending from the first segment bottom surface 104S to the second segment bottom surface 106S, with the first segment bottom surface 104S open and the second segment bottom surface 106S plugged, and a plurality of second cells 110 adjacent to at least one first cell 108, extending from the first segment bottom surface 104S to the second segment bottom surface 106S, with the first segment bottom surface 104S plugged and the second segment bottom surface 106S open. In this case, the honeycomb structure segment 100 can have the first cells 108 and the second cells 110 arranged alternately adjacent to each other with partition walls 112 sandwiched therebetween so that both bottom surfaces present a checkerboard pattern.

[0029] When exhaust gas containing soot is supplied to the bottom surface 104S of the first segment on the upstream side of the honeycomb structure segment 100, the exhaust gas is introduced into the first cells 108 and travels downstream within the first cells 108. Because the bottom surface 106S of the second segment on the downstream side of the first cells 108 is plugged, the exhaust gas passes through the porous ceramic partition walls 112 that separate the first cells 108 from the second cells 110 and flows into the second cells 110. Since the soot cannot pass through the partition walls 112, it is captured and deposited within the first cells 108. After the soot is removed, the clean exhaust gas that flows into the second cells 110 travels downstream within the second cells 110 and flows out from the bottom surface 106S of the second segment on the downstream side.

[0030] The honeycomb structure segment 100 generally has a cylindrical outer shape. For example, it may be a cylindrical shape with a polygonal base, or a cylindrical shape with a base formed by a combination of curves and line segments. Examples of polygonal shapes include quadrilaterals (rectangles, squares, etc.) and hexagons. In a typical embodiment, the honeycomb structure segment 100 may have a rectangular parallelepiped outer shape.

[0031] When a honeycomb structure segment 100 according to one embodiment is observed from the side of the first segment bottom surface 104S or the second segment bottom surface 106S, the side surface 102 of the honeycomb structure segment 100 is composed of a curved line forming a circular arc, a first line segment extending from one end of the curved line, and a second line segment extending from the other end of the curved line in a direction perpendicular to the first line segment (100A in FIG. 1A). When a honeycomb structure segment 100 according to another embodiment is observed from the side of the first segment bottom surface 104S or the second segment bottom surface 106S, the side surface 102 of the honeycomb structure segment 100 is composed of a curved line forming a circular arc, a first line segment extending from one end of the curved line, a second line segment extending from the other end of the curved line, and a third line segment connecting the first line segment and the second line segment in a direction perpendicular to both the first line segment and the second line segment (100B in FIG. 1A).

[0032] The size of the honeycomb structure segment 100 is, for example, a bottom surface area of ​​600 to 3600 mm 2 Typically, it can be 900 to 2500 mm 2 It can be said that:

[0033] The length L (unit: mm) of the line segment connecting the center of gravity G1 of the first segment bottom surface 104S and the center of gravity G2 of the second segment bottom surface 106S can be, for example, 50 to 350 mm, and typically 100 to 250 mm. Within the above length range, from the viewpoint that the effect of improving thermal shock resistance by suppressing bending is easily manifested, the length in the cell extension direction of the honeycomb structure segment 100 is preferably 178 mm to 250 mm, more preferably 203 mm to 200 mm, and even more preferably 254 mm to 150 mm.

[0034] Although there are no limitations on the shape of the cells in a cross section perpendicular to the extension direction (height direction) of the first cells 108 and the second cells 110, a square, a hexagon, an octagon, or a combination thereof is preferred. Among these, a square and a hexagon are preferred. By using the honeycomb structure segment 100 in this way as a particulate filter, the pressure loss when exhaust gas flows through the honeycomb structure segment 100 is reduced, and the purification performance is excellent.

[0035] The means for suppressing bending of the segment bonded body 10 include (1) a means for suppressing bending of each of the plurality of honeycomb structure segments 100 constituting the segment bonded body 10, and (2) a means for suppressing bending of the entire segment bonded body 10 by devising an arrangement of the plurality of honeycomb structure segments 100 constituting the segment bonded body 10. While only one of (1) and (2) may be adopted, it is preferable to combine both means.

[0036] First, the means (1) will be explained. In one embodiment, each of the plurality of honeycomb structure segments 100 constituting the segment bonded assembly 10 has at least one flat side surface 102 used to bond adjacent honeycomb structure segments. In each honeycomb structure segment 100, the flat side surface 102 used to bond adjacent honeycomb structure segments has a degree of curvature. In another embodiment, at least one of the first segment side surface 102A, the second segment side surface 102B, the third segment side surface 102C, and the fourth segment side surface 102D of each of the rectangular parallelepiped honeycomb structure segments 100 constituting the segment bonded assembly 10 is used to bond adjacent honeycomb structure segments. The first segment side surface 102A, the second segment side surface 102B, the third segment side surface 102C, and the fourth segment side surface 102D are all flat side surfaces 102. The first segment side surface, the second segment side surface, the third segment side surface, and the fourth segment side surface used to bond adjacent honeycomb structure segments each have a degree of curvature. In any embodiment, when the maximum bending amount of at least one side surface used to join adjacent honeycomb structure segments in each honeycomb structure segment 100 is Smax (unit: mm), and the length of a line segment connecting the center of gravity G1 of the first segment bottom surface 104S and the center of gravity G2 of the second segment bottom surface 106S is L (unit: mm), it is preferable that Smax / L≦0.010 be satisfied. For each of the multiple rectangular parallelepiped honeycomb structure segments 100, it is more preferable that Smax / L≦0.008 be satisfied, and even more preferable that Smax / L≦0.005 be satisfied. While it is desirable for Smax / L to be as small as possible, taking into account the manufacturing cost, it is common for Smax / L to be 0.001≦Smax / L, typically 0.002≦Smax / L, and more typically 0.003≦Smax / L. Therefore, for each of the multiple rectangular parallelepiped honeycomb structure segments 100, it is preferable to satisfy, for example, 0.001≦Smax / L≦0.010, it is more preferable to satisfy 0.002≦Smax / L≦0.008, and it is even more preferable to satisfy 0.003≦Smax / L≦0.005.

[0037] The amount of bending of the planar side surfaces used to join adjacent honeycomb structure segments is measured by the following procedure. For example, when the honeycomb structure segment 100 is a rectangular parallelepiped, an X-ray CT scanning device is used to CT scan the joined segment assembly 10 to obtain cross-sectional images parallel to the cell extension direction of the honeycomb structure segment 100 to be measured, where the first segment side surface 102A and the third segment side surface 102C (a pair of opposing side surfaces) are located at both ends, at the center in the depth direction of the honeycomb structure segment 100, and the second segment side surface 102B and the fourth segment side surface 102D (the other pair of opposing side surfaces) are located at both ends, at the center in the depth direction of the honeycomb structure segment 100 (see FIG. 5). Based on the cross-sectional images, a distance D (=amount of bending) is calculated between a straight line Q connecting the upper and lower ends of the first segment side surface 102A and a tangent line P that is tangent to the first segment side surface 102A and is parallel to the straight line Q and is farthest from the straight line Q. The distance D (=amount of bending) is similarly determined for the second segment side surface 102B, the third segment side surface 102C, and the fourth segment side surface 102D, and the maximum value of the distance D is calculated as the maximum amount of bending (Smax). If the honeycomb structure segment 100 is not rectangular, the amount of bending can be similarly measured by performing a CT scan so that the planar side surface 102, which is the target of measuring the amount of bending, extends in the depth direction (from the front to the back) in the cross-sectional image.

[0038] It is also desirable that Smax itself is small. Therefore, it is preferable that each of the plurality of honeycomb structure segments 100 constituting the bonded segment assembly 10 has Smax of 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. While it is desirable that Smax be as small as possible, taking into account the balance with manufacturing costs, it is usually 0.1 mm or more, typically 0.3 mm or more, and more typically 0.4 mm or more. Therefore, it is preferable that each of the plurality of honeycomb structure segments 100 constituting the bonded segment assembly 10 has Smax of, for example, 0.1 to 2.0 mm, more preferably 0.3 to 1.0 mm, and even more preferably 0.4 mm to 0.5 mm.

[0039] Next, the means (2) will be described. As described above, the segment bonded assembly 10 according to one embodiment of the present invention includes a plurality of rectangular parallelepiped honeycomb structure segments 100 whose side surfaces 102 are bonded to one another via bonding materials 107. Since it is difficult to make all of the first segment side surface 102A, the second segment side surface 102B, the third segment side surface 102C, and the fourth segment side surface 102D constituting each rectangular parallelepiped honeycomb structure segment 100 flat, it is possible to identify the side surface having the maximum amount of curvature Smax from among these. In this case, if a plurality of honeycomb structure segments are bonded to one another while aligning the orientation of the side surface having the maximum amount of curvature Smax, the bond width becomes uniform, preventing stress concentration and improving thermal shock resistance and isostatic fracture strength.

[0040] Therefore, the bonded segment assembly 10 according to one embodiment of the present invention has at least two rectangular parallelepiped honeycomb structure segments 100 in which the side surfaces 102 having the largest amount of curvature are aligned, among a plurality of rectangular parallelepiped honeycomb structure segments 100 whose side surfaces 102 are aligned via a bonding material 107. In a preferred embodiment, 30% or more, more preferably 50% or more, and even more preferably 80% or more of the total number of rectangular parallelepiped honeycomb structure segments 100 included in the bonded segment assembly 10 have the side surfaces 102 having the largest amount of curvature aligned. In the most preferred embodiment, the side surfaces 102 having the largest amount of curvature aligned for all of the rectangular parallelepiped honeycomb structure segments 100 included in the bonded segment assembly 10.

[0041] The material of the honeycomb structure segment 100 is not limited to, but may include, porous ceramics. Examples of ceramics include cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconia, spinel, indialite, sapphirine, corundum, titania, and silicon nitride. These ceramics may contain one type alone or two or more types simultaneously. Other materials for the honeycomb structure segment 100 include porous sintered metals containing alloy components primarily composed of one or more elements selected from the group consisting of Fe, Cr, Mo, and Ni.

[0042] Among the above porous ceramics, silicon-silicon carbide composites are suitable for filter applications due to their excellent heat resistance, thermal shock resistance, and oxidation resistance. The silicon-silicon carbide composite contains silicon carbide particles as aggregate and silicon as a binder that bonds the silicon carbide particles, and preferably the silicon carbide particles are bonded together by the silicon so as to form pores between the silicon carbide particles.

[0043] However, silicon-silicon carbide composite segments are prone to bending due to shrinkage during firing. Furthermore, when the porosity is high, the bending margin increases, making the segments more likely to bend during firing. When multiple honeycomb structure segments 100 are joined together with a bonding material, if the bending amount of each honeycomb structure segment 100 is large, it restricts the segments that can be joined. Furthermore, when the honeycomb structure segments 100 are joined together through the bonding and coating processes, the bending tends to become even larger. Therefore, when the honeycomb structure segment 100 contains a silicon-silicon carbide composite, typically when it contains 50% by mass or more of the silicon-silicon carbide composite, more typically when it contains 60% by mass or more of the silicon-silicon carbide composite, and even more typically when it contains 70% by mass or more of the silicon-silicon carbide composite, it is necessary to optimize the blending ratio of silicon and silicon carbide, as well as the type and blending ratio of the sintering aid, to suppress bending.

[0044] Specifically, because bending is easily suppressed, the honeycomb structure segment 100 preferably contains 70 parts by mass or more of silicon carbide, more preferably 75 parts by mass or more, and even more preferably 80 parts by mass or more, per 100 parts by mass of silicon carbide and silicon combined. On the other hand, from the viewpoint of improving thermal conductivity and strength, the honeycomb structure segment 100 preferably contains 95 parts by mass or less of silicon carbide, more preferably 90 parts by mass or less, and even more preferably 85 parts by mass or less, per 100 parts by mass of silicon carbide and silicon combined. Therefore, the honeycomb structure segment 100 preferably contains 70 parts by mass or more and 95 parts by mass or less of silicon carbide, more preferably 75 parts by mass or more and 90 parts by mass or less, and even more preferably 80 parts by mass or more and 85 parts by mass or less, per 100 parts by mass of silicon carbide and silicon combined.

[0045] Furthermore, the honeycomb structure segment 100 preferably contains silicon oxide, strontium oxide, and aluminum oxide as firing aids to facilitate the melting of metallic silicon and thereby improve thermal conductivity and strength. In this case, since the amount of silicon melting can be controlled, the honeycomb structure segment 100 preferably contains 1.0% or more of aluminum oxide relative to the total mass (100%) of silicon oxide, strontium oxide, and aluminum oxide, more preferably 3.0% or more, and even more preferably 6.0% or more. However, if the aluminum oxide content is too high, the thermal conductivity and strength tend to decrease. Therefore, the honeycomb structure segment 100 preferably contains 15.0% or less of aluminum oxide relative to the total mass (100%) of silicon oxide, strontium oxide, and aluminum oxide, more preferably 12.0% or less, and even more preferably 9.0% or less. Therefore, the honeycomb structure segment 100 preferably contains, for example, 1.0 to 15.0% aluminum oxide relative to the total mass (100%) of silicon oxide, strontium oxide, and aluminum oxide, more preferably 3.0 to 12.0%, and even more preferably 6.0 to 9.0%.

[0046] From the viewpoint of suppressing bending, it is preferable to control the content of silicon oxide, strontium oxide, and aluminum oxide relative to the total mass of silicon carbide and silicon. Specifically, the plurality of rectangular parallelepiped honeycomb structure segments constituting the honeycomb joined body, desirably all of the plurality of honeycomb structure segments constituting the honeycomb joined body, each contain preferably 5.0 to 35.0 parts by mass of silicon oxide per 100 parts by mass of silicon carbide and silicon, more preferably 8.0 to 25.0 parts by mass, and even more preferably 11.0 to 20.0 parts by mass. Furthermore, each honeycomb structure segment contains preferably 0.0 to 10.0 parts by mass of strontium oxide per 100 parts by mass of silicon carbide and silicon, more preferably 1.0 to 7.0 parts by mass, and even more preferably 2.0 to 5.0 parts by mass. Furthermore, each honeycomb structure segment preferably contains 0.2 to 2.5 parts by mass, more preferably 0.5 to 2.0 parts by mass, and even more preferably 1.0 to 1.5 parts by mass of aluminum oxide per 100 parts by mass of silicon carbide and silicon combined.

[0047] It is also advantageous to prevent bending by not making the porosity of the honeycomb structure segment 100 too high. Specifically, the upper limit of the porosity of each of the rectangular parallelepiped honeycomb structure segments constituting the honeycomb bonded body, desirably all of the honeycomb structure segments constituting the honeycomb bonded body, is preferably 70% or less, more preferably 60% or less, and even more preferably 50% or less. Not making the porosity of the honeycomb structure segment 100 too high is also advantageous for ensuring strength and thermal conductivity. However, to prevent excessive increase in pressure loss when gas is flowed, the lower limit of the porosity of the honeycomb structure segment 100 is preferably 30% or more, more preferably 40% or more, and even more preferably 45% or more. Therefore, the porosity of the honeycomb structure segment 100 is, for example, preferably 30 to 70%, more preferably 40 to 60%, and even more preferably 45 to 50%.

[0048] Here, the porosity of the honeycomb structure segment 100 is given as an average value when a plurality of samples of the partition walls 112 constituting the honeycomb structure segment 100 are uniformly collected from the honeycomb structure segment 100 and the porosity of each sample is measured by mercury porosimetry. Specifically, the porosity is calculated by mercury porosimetry (in accordance with JIS R 1655:2003).

[0049] The average thickness of the partition walls 112 in the honeycomb structure segment 100 is not limited, but is preferably 0.1 mm to 0.5 mm. By setting the average thickness of the partition walls 112 to preferably 0.1 mm or more, more preferably 0.2 mm or more, the strength of the honeycomb structure segment 100 can be ensured. Furthermore, by setting the average thickness of the partition walls 112 to preferably 0.5 mm or less, more preferably 0.4 mm or less, the pressure loss when exhaust gas is caused to flow through the honeycomb structure segment 100 can be kept low.

[0050] In this specification, the partition wall thickness refers to the length of a line segment that crosses the partition wall when the line segment connects the centers of gravity of adjacent cells in a cross section perpendicular to the cell extension direction. The average partition wall thickness refers to the average value of the thicknesses of all partition walls in each honeycomb structure segment.

[0051] The cell density of the honeycomb structure segments ranges from 50 to 400 cells / in² (7.7 to 62.0 cells / cm²). 2 ), and 70 to 370 cells / in² (10.8 to 57.3 cells / cm²) 2 ), and 80 to 320 cells / in² (12.4 to 49.6 cells / cm²) 2 It is more preferable that the cell density of the honeycomb structure segment is 50 cells / in 2 (7.7 cells / cm 2 ). 2 ), sufficient strength may not be obtained. On the other hand, if the cell density of the honeycomb structure segment is 400 cells / square inch (62.0 cells / cm 2), the pressure loss becomes too high, which may result in a decrease in engine output when used as a DPF. In this specification, the cell density is a value obtained by dividing the number of cells by the area of ​​one of the bottom surfaces (the bottom surface of the first segment or the bottom surface of the second segment) of the honeycomb structure segment (the total area of ​​the partition walls and cells excluding the outer peripheral side walls).

[0052] In each honeycomb structure segment, the average thickness of the outer peripheral side wall 113 is not limited, but may be, for example, 0.1 mm to 0.5 mm, and preferably 0.15 mm to 0.4 mm, in consideration of the balance between the strength and filter performance of the honeycomb structure segment 100. In this specification, the average thickness of the outer peripheral side wall refers to the average value when the thicknesses of multiple points on the outer peripheral side wall are measured without bias in a cross section perpendicular to the cell extension direction.

[0053] (4. Characteristics of honeycomb structure segments) Hereinafter, some characteristics that can be exhibited by a honeycomb structure segment according to one embodiment of the present invention will be described.

[0054] [4-1. Thermal conductivity] A honeycomb structure segment with a higher thermal conductivity can suppress the occurrence of temperature differences within the honeycomb structure segment, thereby improving thermal shock resistance. Furthermore, a honeycomb structure segment with a higher thermal conductivity can improve the removal performance when PM trapped in the honeycomb structure segment is burned and removed for filter regeneration. In this regard, the honeycomb structure segment according to one embodiment of the present invention can exhibit high thermal conductivity. Specifically, the plurality of rectangular parallelepiped honeycomb structure segments constituting the honeycomb joined body, desirably all of the plurality of honeycomb structure segments constituting the honeycomb joined body, each have a thermal conductivity at 50°C measured by a disc heat flow meter method in accordance with ASTM E1530 of 3 W / (m·K) or more, preferably 10 W / (m·K) or more, and more preferably 20 W / (m·K) or more. Although there is no particular upper limit set for the thermal conductivity, taking into account the balance with manufacturing costs, it is usually 40 W / (m·K) or less, typically 30 W / (m·K) or less, and more typically 25 W / (m·K) or less. Therefore, each honeycomb structure segment can exhibit a thermal conductivity of, for example, 3 to 40 W / (m·K), preferably 10 to 30 W / (m·K), and more preferably 20 to 25 W / (m·K).

[0055] The thermal conductivity of a honeycomb structure segment is measured as follows: A rectangular columnar sample measuring 35 mm × 35 mm × 20 mm (length in the cell extension direction) is cut out from the center of the honeycomb structure segment in the radial and vertical directions, and the thermal conductivity of the sample is measured under the above-mentioned temperature conditions using a measuring instrument conforming to ASTM E1530, and the measured value is used.

[0056] [4-2. Average Coefficient of Linear Expansion (CTE)] It is desirable that the honeycomb structure segments have small thermal expansion. Specifically, the average linear expansion coefficient of each of the rectangular parallelepiped honeycomb structure segments constituting the honeycomb joined body, preferably all of the honeycomb structure segments constituting the honeycomb joined body, measured according to JIS R1618:2002 when the temperature is changed from 40°C to 800°C, is 5.5 × 10 -6 / K or less. -6 / K or less, the thermal stress during exhaust gas treatment and filter regeneration, when the temperature of the honeycomb structure segments becomes high, is reduced, and the thermal shock resistance is significantly improved. -6 / K or less is more preferable, and 5.3 × 10 -6 Although there is no particular restriction on the lower limit of the average linear expansion coefficient, from the viewpoint of ease of production, the average linear expansion coefficient is preferably 3.0×10 -6 / K or more is preferable, and 3.5 × 10 -6 / K or more is more preferable, and 4.0 × 10 -6 Therefore, the average linear expansion coefficient is, for example, 3.0×10 -6 / K or more 5.5×10 -6 / K or less, and 3.5 × 10 -6 / K or more 5.4×10 -6 / K or less is more preferable, and 4.0 × 10 -6 / K or more 5.3×10 -6 It is even more preferable that the .beta..times ...

[0057] The average linear expansion coefficient of the honeycomb structure segment is measured by the following procedure: A rectangular columnar sample measuring 3 mm × 3 mm × 15 mm (length in the cell extension direction) is cut out from the center of the honeycomb structure segment in the radial and height directions, and the average linear expansion coefficient of the sample is measured under the above-mentioned temperature change conditions, and this is taken as the measured value.

[0058] (5. Bonding material) The bonding material 107 serves to bond the side surfaces 102 of the honeycomb structure segments 100 together. In one embodiment, the bonding material 107 is interposed in the form of a layer between the side surfaces 102 of the opposing honeycomb structure segments 100. The thickness of the bonding material 107 (the length in the direction perpendicular to the bonding surface of the bonding material with the honeycomb structure segment) is determined taking into consideration the bonding force (shear strength) between the honeycomb structure segments 100, and is appropriately selected, for example, within the range of 0.5 to 3.0 mm.

[0059] In one embodiment, the bonding material 107 is porous. When the bonding material 107 is porous, the higher the porosity, the more likely it is to exhibit a stress relaxation effect and thereby obtain thermal shock resistance. Therefore, the lower limit of the porosity of the bonding material is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. However, from the viewpoint of ensuring bonding strength, the upper limit of the porosity of the bonding material is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. Therefore, the porosity of the bonding material is, for example, preferably 40 to 80%, more preferably 50 to 75%, and even more preferably 60 to 70%.

[0060] The porosity of the bonding material was measured by collecting multiple samples of the bonding material evenly from the segment bonded body 10 and measuring the total pore volume (unit: cm) by mercury porosimetry (in accordance with JIS R 1655:2003). 3 / g) and apparent density by Archimedes method in water (unit: g / cm 3 ) In other words, the porosity here is the porosity before the catalyst is supported.

[0061] The bonding material can contain one or more ceramics or other inorganic materials such as cordierite, mullite, alumina, silica, alumina silicate, wollastonite, mica, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composite material (e.g., Si-bonded SiC), cordierite-silicon carbide composite, zirconia, spinel, indialite, sapphirine, corundum, titania, silicon nitride, etc. When the honeycomb structure segment 100 contains a silicon-silicon carbide composite material, the bonding material preferably contains silicon carbide, alumina silicate, mullite, or alumina.

[0062] (6. Method for manufacturing a segment bonded assembly) In a first embodiment, the method for producing a segment bonded body according to the present invention comprises: A step 1 of preparing a plurality of porous ceramic columnar honeycomb structure segments each having an outer peripheral side wall and partition walls that define a plurality of cells extending from a first bottom surface to a second bottom surface on the inner peripheral side of the outer peripheral side wall; a step 2 of bonding the side surfaces of the plurality of porous ceramic columnar honeycomb structure segments together using a bonding slurry and drying the bonding slurry; Includes.

[0063] In step 1, a plurality of honeycomb structure segments made of porous ceramics are prepared, each having an outer peripheral side wall and partition walls that define a plurality of cells extending from a first bottom surface to a second bottom surface on the inner peripheral side of the outer peripheral side wall. These honeycomb structure segments made of porous ceramics can be manufactured by adding some ingenuity to the manufacturing process in accordance with a known manufacturing method for a honeycomb structure, and an example of the procedure is shown below.

[0064] First, a raw material composition containing ceramic raw materials, a dispersion medium, a pore-forming material, and a binder is kneaded to prepare a clay, which is then extruded and dried to produce a honeycomb formed body. Additives such as dispersants can be blended into the raw material composition as needed. During extrusion molding, a die having the desired overall shape, cell shape, partition wall thickness, cell density, etc. can be used.

[0065] In the drying step, conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, etc. Among them, a drying method that combines hot air drying with microwave drying or dielectric drying is preferred because it can dry the entire formed body quickly and uniformly. The plugging portions can be formed by forming plugging portions at predetermined positions on both bottom surfaces of the dried honeycomb formed body and then drying the plugging portions.

[0066] Ceramic raw materials are the raw materials that remain after firing of metal oxides, metals, etc. and form the skeleton of the fired columnar honeycomb formed body (columnar honeycomb structure). Therefore, firing aids are also considered to be a type of ceramic raw material. Ceramic raw materials can be provided in the form of, for example, powder. Examples of ceramic raw materials include cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconia, spinel, indialite, sapphirine, corundum, titania, and silicon nitride. Specific examples include, but are not limited to, silicon carbide, silicon, silica, talc, alumina, kaolin, serpentine, pyroferrite, brucite, boehmite, mullite, magnesite, and aluminum hydroxide. Silicon oxide, strontium oxide, and aluminum oxide, which are added as firing aids, are also considered to be ceramic raw materials. The ceramic raw material may be used singly or in combination of two or more kinds.

[0067] Examples of the dispersion medium include water and a mixed solvent of water and an organic solvent such as alcohol, with water being particularly preferred.

[0068] The pore-forming material is not particularly limited as long as it forms pores after firing, and examples thereof include wheat flour, starch, foamed resin, water-absorbent resin, silica gel, carbon (e.g., graphite, coke), ceramic balloons, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic, and phenol. One type of pore-forming material may be used alone, or two or more types may be used in combination. From the viewpoint of increasing the porosity of the honeycomb structure, the content of the pore-forming material is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the ceramic raw materials. From the viewpoint of ensuring the strength of the honeycomb structure, the content of the pore-forming material is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the ceramic raw materials.

[0069] Examples of binders include organic binders such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. It is particularly preferable to use a combination of methyl cellulose and hydroxypropyl methyl cellulose. Furthermore, from the viewpoint of increasing the strength of the honeycomb formed body before firing, the binder content is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of the ceramic raw materials. From the viewpoint of suppressing cracks due to abnormal heat generation during the firing process, the binder content is preferably 9 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of the ceramic raw materials. One type of binder may be used alone, or two or more types may be used in combination.

[0070] The dispersant may be ethylene glycol, dextrin, fatty acid soap, polyether polyol, etc. One type of dispersant may be used alone, or two or more types may be used in combination. The content of the dispersant is preferably 0 to 2 parts by mass per 100 parts by mass of the ceramic raw material.

[0071] When plugging the bottom surface of a honeycomb formed body, the method is not particularly limited, and a well-known method can be used, such as filling the cell openings on the bottom surface with a plugging slurry, which has been applied with a predetermined mask. The material for the plugging portions is not particularly limited, but ceramics are preferred from the viewpoints of strength and heat resistance. Ceramics preferably contain one or more of cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconia, spinel, indialite, sapphirine, corundum, titania, silicon nitride, and the like. The plugging portions are preferably formed from a material containing a total of 50% by mass or more of these ceramics, and more preferably from a material containing 80% by mass or more. It is even more preferred that the plugging portions have the same material composition as the main body of the honeycomb formed body, as this allows for the same expansion coefficient during firing and leads to improved durability.

[0072] The dried honeycomb formed body is subjected to a degreasing process and a firing process to manufacture a honeycomb structure segment. The conditions for the degreasing process and the firing process may be known conditions depending on the material composition of the honeycomb formed body, and no particular explanation is required, but specific examples of the conditions are given below.

[0073] The degreasing step will now be described. The combustion temperature of the binder is about 200°C, and the combustion temperature of the pore-forming material is about 300 to 1000°C. Therefore, the degreasing step can be carried out by heating the honeycomb formed body to a temperature in the range of about 200 to 1000°C. The heating time is not particularly limited, but is usually about 10 to 100 hours. The honeycomb formed body after the degreasing step is called a calcined body.

[0074] The firing step may vary depending on the material composition of the honeycomb formed body, but may be carried out, for example, by heating the calcined body to 1350 to 1600° C. in an air atmosphere and holding the temperature for 3 to 10 hours.

[0075] In order to suppress bending of the columnar honeycomb structure segment produced in this manner, it is important to minimize the amount of shrinkage of the honeycomb formed body during firing. Specifically, the shrinkage ratio (before firing / after firing) of the honeycomb formed body during firing is preferably 1.000 to 1.040 in the overall length direction and 1.000 to 1.050 in the radial direction, more preferably 1.000 to 1.020 and 1.000 to 1.030 in the radial direction, and even more preferably 1.000 to 1.010 and 1.000 to 1.020 in the radial direction. The shrinkage ratio in the overall length direction is calculated by measuring, with a vernier caliper, the change in length L of the line segment connecting the center of gravity G1 of the first segment bottom surface 104S and the center of gravity G2 of the second segment bottom surface 106S before and after firing. The radial shrinkage rate is determined by calculating the change in the length of the line segment M connecting the centers of gravity G3 and G4 of the opposing side surfaces 102 before and after firing using a vernier caliper, and the larger value is taken as the measured value.

[0076] To reduce the shrinkage rate during firing, it is also preferable to make the particle size of the ceramic raw material powder fine and uniform (e.g., a median diameter of 1 to 50 μm as determined by laser diffraction / scattering), and to adjust firing conditions such as the firing temperature (e.g., 1400 to 2000°C), holding time (e.g., 1 to 5 hours), and atmosphere composition (e.g., an inert atmosphere). In particular, when the goal is to produce columnar honeycomb structure segments containing a silicon-silicon carbide composite, it is important, as mentioned above, to optimize the compounding ratio of silicon and silicon carbide, as well as the type and compounding ratio of the firing aid.

[0077] Other methods for suppressing bending of honeycomb structure segments include lowering the firing temperature and reducing the amount of binder.

[0078] In step 2, the side surfaces of multiple porous ceramic columnar honeycomb structure segments are bonded together using a bonding slurry, which is then dried. This converts the bonding slurry into a bonding material, producing a bonded segment body. Specifically, the bonded segment body can be manufactured by the following procedure. With a film for preventing adhesion of the bonding material attached to both bottom surfaces of each honeycomb structure segment, the bonding material is applied to the bonding surfaces (side surfaces). Next, these segments are arranged adjacent to each other with their side surfaces facing each other, and the adjacent segments are pressure-bonded together and then heated and dried. In this way, a bonded segment body is manufactured in which the side surfaces of adjacent segments are bonded together with the bonding material.

[0079] The material of the film for preventing adhesion of a bonding material is not particularly limited, but suitable materials include synthetic resins such as polypropylene (PP), polyethylene terephthalate (PET), polyimide, and Teflon (registered trademark). The film preferably has an adhesive layer, and the adhesive layer is preferably made of an acrylic resin, a rubber resin (e.g., a rubber whose main component is natural rubber or synthetic rubber), or a silicone resin.

[0080] The bonding slurry can be prepared by mixing, for example, anisotropic inorganic powder, aggregate, pore-forming material, dispersion medium (e.g., water, etc.), and, if necessary, additives such as binders and dispersants.

[0081] The anisotropic inorganic powder may be made of natural minerals or artificial ceramic fibers. Suitable natural minerals include acicular or plate-like natural minerals such as wollastonite, mica, talc, sepiolite, palygorskite, and attapulgite. Suitable artificial ceramic fibers include RCF (amorphous refractory ceramic fiber primarily composed of alumina and silica), alumina fiber, mullite fiber, carbon fiber, silicon carbide fiber, boron nitride fiber, potassium titanate fiber, and zinc oxide fiber. One type of anisotropic inorganic powder may be used, or two or more types may be used in combination.

[0082] Examples of aggregate materials include ceramics such as cordierite, mullite, zirconium phosphate, aluminum titanate, silicon carbide, silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconia, spinel, indialite, sapphirine, corundum, titania, and silicon nitride.

[0083] The binder may be either an inorganic binder or an organic binder. Examples of organic binders include methyl cellulose, hydroxypropoxyl methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and methyl cellulose. Examples of inorganic binders include clay minerals such as bentonite, montmorillonite, sepiolite, and attapulgite. One type of binder may be used, or two or more types may be used in combination.

[0084] The bonding slurry may further contain a dispersant such as polyethylene glycol oleate.

[0085] Examples of the pore-forming material include hollow or solid organic balloons such as foamed resin, water-absorbent resins, organic substances such as starch, and inorganic substances such as fly ash balloons. One type of pore-forming material may be used, or two or more types may be used in combination.

[0086] If the solid content concentration of the bonding slurry is too low, the bonding width will be thin, whereas if it is too high, the bonding width will be thick. Therefore, the solid content concentration of the bonding slurry is, for example, preferably 50 to 90 mass %, more preferably 60 to 80 mass %, and even more preferably 65 to 75 mass %.

[0087] The outer periphery of the bonded segments prepared by the above procedure may be ground to a desired shape (e.g., cylindrical), and a coating material may be applied to the outer periphery side surface, followed by drying and heat treatment to form an outer periphery wall. Drying and heat treatment may be performed, for example, at 400 to 700°C, preferably 500 to 600°C, in an air atmosphere for 0.5 to 3 hours, preferably 0.5 to 1 hour. The coating material is not particularly limited, and known outer periphery coating materials can be used. Examples of outer periphery coating materials include those prepared by adding inorganic raw materials such as inorganic fibers, colloidal silica, clay, and ceramic particles to water, and adding additives such as organic binders, foamed resins, and dispersants, and kneading them to form a slurry. The method for applying the outer periphery coating material is not particularly limited, and known methods can be used.

[0088] An appropriate catalyst may be loaded on the filter depending on the application. Examples of a method for loading a catalyst on the filter include a method in which a catalyst slurry is introduced into the cells by a conventionally known suction method or the like, and the catalyst is attached to the surfaces and pores of the partition walls, and then high-temperature treatment is performed to bake the catalyst contained in the catalyst slurry onto the partition walls.

[0089] The catalyst may be, but is not limited to, an oxidation catalyst (DOC) for oxidizing and burning hydrocarbons (HC) and carbon monoxide (CO) to increase the temperature of the exhaust gas, a PM combustion catalyst for assisting the combustion of PM such as soot, a nitrogen oxide (NO x SCR catalysts and NSR catalysts for removing hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO xExamples of catalysts include three-way catalysts capable of simultaneously removing Cr, Fe, Co, Ni, Cu, Zn, Zr, Sc, Ti, V, Cr, and the like. The catalyst may contain, as appropriate, noble metals (Pt, Pd, Rh, etc.), alkali metals (Li, Na, K, Cs, etc.), alkaline earth metals (Ca, Ba, Sr, etc.), rare earth elements (Ce, Sm, Gd, Nd, Y, La, Pr, etc.), transition metals (Mn, Fe, Co, Ni, Cu, Zn, Zr, Sc, Ti, V, Cr, etc.), and the like.

[0090] In particular, DPFs for passenger cars have the advantage of trapping soot and NO x In order to simultaneously perform the purification function, the DPF is loaded with an SCR catalyst such as Cu-substituted zeolite or Fe-substituted zeolite. In this case, NO is removed by ammonia obtained by decomposing urea on board. x Purification can be carried out. [Example]

[0091] The following examples are provided to provide a better understanding of the present invention and its advantages, but the present invention is not limited to these examples.

[0092] <Examples 1 to 6, Comparative Examples 1 to 3> (1. Manufacturing honeycomb structure segments) Silicon carbide (SiC) powder, silicon (Si) powder, silicon oxide (SiO2) powder, strontium oxide (SrO) powder, and aluminum oxide (Al2O3) powder were mixed in the mass proportions shown in Table 1 for the test number, to which a pore-forming material (starch), organic binder (hydroxypropyl methylcellulose), and surfactant (oleic acid ester) were added in the mass proportions shown in Table 1, and an appropriate amount of water was then added to obtain a clay. The median diameters of the silicon carbide (SiC) powder, silicon (Si) powder, and pore-forming material, measured by laser diffraction / scattering, are shown in Table 1.

[0093] [Table 1]

[0094] This clay was extruded through a predetermined die and dried to obtain a rectangular parallelepiped honeycomb formed body having an outer peripheral sidewall and partition walls that defined a plurality of cells extending from the first bottom surface to the second bottom surface. Plugging portions were formed at one end of each cell of this rectangular parallelepiped honeycomb formed body so that both bottom surfaces of the body had a checkerboard pattern. That is, the plugging portions were formed so that adjacent cells were plugged at their opposite ends. The plugging portions were made of the same material as the columnar honeycomb formed body. After the plugging portions were formed and dried, the columnar honeycomb formed body was degreased in an air atmosphere at approximately 450°C and then fired in an Ar atmosphere at approximately 1450°C to bond the SiC particles in the formed body with Si, thereby obtaining a rectangular parallelepiped honeycomb structure segment with the following specifications.

[0095] Bottom shape: 35mm square The total length (length L of the line segment connecting the center of gravity of the bottom of the first segment and the center of gravity of the bottom of the second segment) is listed in Table 3. Porosity: as shown in Table 2 Average thickness of partition wall: 0.305 mm Cell cross-sectional shape: square Cell density: 44 cells / cm 2 Average thickness of outer wall: 0.5 mm Composition: As shown in Table 2 (composition analysis was performed by fluorescent X-ray and inert gas fusion method).

[0096] The shrinkage rates (in the overall length direction and in the radial direction) of the honeycomb formed bodies for each test number during firing were measured using the method described above, and the results are shown in Table 3. The honeycomb structure segments for each test number were produced in the number required to manufacture the segment bonded body described later, and Table 3 shows their average values.

[0097] (2. Preparation of Bonding Slurry) Next, anisotropic inorganic powder (mullite fiber), aggregate (silicon carbide, cordierite), pore-forming material (expanded resin), binder (carboxymethyl cellulose), and dispersant (PEG monophosphate ester) were mixed in a mixer to obtain a bonding slurry (solid content = 73% by mass).

[0098] (3. Manufacturing of Segment Joint) This bonding slurry was applied to the side of a rectangular parallelepiped honeycomb structure segment obtained by the above-mentioned manufacturing procedure to a thickness of approximately 1 mm, and another honeycomb structure segment obtained by the above-mentioned manufacturing procedure was placed on top of it.This process was repeated to produce a segment stack consisting of a total of 16 honeycomb structure segments combined in a 4 x 4 matrix.The entire assembly was then bonded by applying external pressure as appropriate, and then dried at 120°C for 2 hours to obtain a bonded segment.The bonded segment assembly is made up of multiple rectangular parallelepiped honeycomb structure segments bonded together at the side surfaces via a bonding material.

[0099] When assembling the segment bonded bodies, the percentage of the 16 rectangular honeycomb structure segments whose sides were bonded together using bonding material, in which the orientation of the side with the largest amount of bending was consistent, was changed depending on the test number as shown in Table 3.

[0100] The outer periphery of this bonded segment assembly was ground to give it a cylindrical outer shape, and then a coating material with the same composition as the bonding slurry was applied to the machined surface to reform the outer wall. The bonded segment assembly was then dried and hardened in air at 600°C for 2 hours to obtain the final bonded segment assembly (160 mmφ) for each test example. The bonded segment assembly contained four rectangular honeycomb structure segments. The thickness of the bonding material was approximately 1.1 mm. The number of bonded segment assembly units required to conduct the following evaluation tests was produced.

[0101] (4. Characteristics of Segment Joints) The segment bonded assembly obtained above was evaluated for the following properties as described above. The results are shown in Table 3. (1) Maximum bending amount of honeycomb structure segment Smax The maximum bending amount Smax was measured for each honeycomb structure segment constituting the segment bonded assembly for each test number according to the method described above. The maximum value of the multiple Smax values ​​measured for each honeycomb structure segment is shown as "Smax" in Table 3. The ratio of "Smax" to the total length L (Smax / L) is also shown in Table 3. (2) Bending of the segment joint Fmax (3) Thermal conductivity at 50°C (measured by selecting an arbitrary segment before bonding, but the same value was obtained when measured for the bonded body.) (4) Average coefficient of linear expansion (CTE) when the temperature was changed from 40°C to 800°C (measured by selecting an arbitrary segment before bonding, but the same value was obtained when measured for the bonded body.) (5) Isostatic fracture strength (isostrength) (6) ESP crack temperature The porosity of the bonding material was approximately 70% for all of the bonded segments.

[0102] [Table 2]

[0103] [Table 3] [Explanation of symbols]

[0104] 10: Segment joint 100: Honeycomb structure segment 102: Side 102A: First segment side 102B: Second segment side 102C: Third segment side 102D: Fourth segment side 103:Outer wall 104: First bottom surface 104S: Bottom of first segment 106:Second bottom surface 106S: Bottom of second segment 107: Bonding material 108: First cell 110: Second cell 112: Bulkhead 113: Outer wall 121: Turntable 122: Laser displacement meter 124: Laser 126: Post

Claims

1. A segment conjugate, The segment bonded body has a plurality of honeycomb structure segments, at least one of which has a flat side surface bonded to another via a bonding material, Each of the plurality of honeycomb structure segments has a first segment bottom surface, a second segment bottom surface, an outer peripheral side wall having at least one flat side surface connecting the first segment bottom surface and the second segment bottom surface, and a porous ceramic partition wall disposed inside the outer peripheral side wall and defining a plurality of cells extending from the first segment bottom surface to the second segment bottom surface, In each of the plurality of honeycomb structure segments, when the maximum bending amount of the at least one planar side surface used for joining the adjacent honeycomb structure segments is defined as Smax (unit: mm) and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is defined as L (unit: mm), Smax / L≦0.010 is satisfied. Segmental junction.

2. 2. The segment bonded assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has an Smax of 2.0 mm or less.

3. 2. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has an Smax of 1.0 mm or less.

4. 3. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has an L of 50 to 350 mm.

5. the segment joint has a cylindrical outer shape with an outer peripheral side surface, a first circular bottom surface, and a second circular bottom surface; With a line segment connecting the center of gravity of the first circular bottom surface and the center of gravity of the second circular bottom surface as a central axis, the distances in the same radial direction from the central axis to the outer peripheral side surface at a height position 10 mm inward from the first circular bottom surface in the direction of extension of the central axis, a height position 10 mm inward from the second circular bottom surface in the direction of extension of the central axis, and a height position of the midpoint of the central axis are respectively defined as R 1 , R 2 and R 3 Let |R 3 - (R 1 +R 2 ) / 2| in the radial direction where the absolute value of |R 3 - (R 1 +R 2 3. The joined segment assembly according to claim 1, wherein Fmax is 2.0 mm or less, where Fmax is the sum of the square root of the square root of the segment and the square root of the axial length of the segment.

6. 6. The joined segment assembly according to claim 5, wherein Fmax is 1.0 mm or less.

7. 3. The joined segment assembly according to claim 1, wherein the isostatic fracture strength is 1.0 MPa or more.

8. 3. The joined segments according to claim 1 or 2, wherein the joined segments are heated in an electric furnace at a set temperature for 60 minutes (if the volume of the joined segments is 5 L or less) or for 120 minutes (if the volume of the joined segments is more than 5 L), then removed from the electric furnace, allowed to cool to room temperature, and visually inspected to determine whether or not a crack having a length of 3 mm or more has occurred in the joined segments; this step is repeated from an initial setting temperature of 200°C, while increasing the set temperature by 50°C in increments until a crack is observed; and the set temperature at which a crack is observed is 250°C or higher.

9. 3. The segment bonded assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has a thermal conductivity of 3 W / (m·K) or more at 50° C. as measured by a disc heat flow meter method in accordance with ASTM E1530.

10. Each of the plurality of honeycomb structure segments has an average linear expansion coefficient of 5.5×10 when measured according to JIS R1618:2002 at temperatures ranging from 40° C. to 800° C. -6 3. The segment joint assembly according to claim 1, wherein the tensile strength is 1 / K or less.

11. 3. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments has a porosity of 70% or less.

12. 12. The segment bonded assembly according to claim 11, wherein each of the plurality of honeycomb structure segments has a porosity of 30% or more and 70% or less.

13. 3. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments contains 70 parts by mass or more of silicon carbide per 100 parts by mass of the total of silicon carbide and silicon.

14. 3. The segment bonded assembly according to claim 1, wherein each of the plurality of honeycomb structure segments contains silicon oxide, strontium oxide, and aluminum oxide, and the content of aluminum oxide is 1.0% or more based on the total mass of silicon oxide, strontium oxide, and aluminum oxide.

15. 3. The bonded segment assembly according to claim 1, wherein each of the plurality of honeycomb structure segments contains 0.2 to 2.5 parts by mass of aluminum oxide per 100 parts by mass of silicon carbide and silicon combined.

16. A segment conjugate, the segment bonded body has a plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via a bonding material, Each of the plurality of rectangular parallelepiped honeycomb structure segments has an outer peripheral side wall having a planar first segment side surface, a planar second segment side surface, a planar third segment side surface, and a planar fourth segment side surface, a first segment bottom surface, a second segment bottom surface, and porous ceramic partition walls disposed inside the outer peripheral side wall and defining a plurality of cells extending from the first segment bottom surface to the second segment bottom surface, In each of the plurality of rectangular parallelepiped honeycomb structure segments, when the maximum bending amount among the bending amounts of the first segment side surface, the second segment side surface, the third segment side surface, and the fourth segment side surface used to join adjacent honeycomb structure segments is defined as Smax (unit: mm), and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is defined as L (unit: mm), Smax / L≦0.010 is satisfied. Segmental junction.

17. 17. The segment bonded assembly according to claim 16, wherein among the plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via bonding material, there are at least two rectangular parallelepiped honeycomb structure segments whose side surfaces have the largest amount of bending and whose orientations are the same.

18. 18. The segment bonded assembly according to claim 17, wherein 30% or more of the total number of the plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via bonding material have the same orientation of the side surface having the largest amount of bending.

19. 18. The segment bonded assembly according to claim 17, wherein the orientation of the side having the maximum amount of bending is consistent for all of the plurality of rectangular honeycomb structure segments whose side surfaces are bonded to each other via bonding material.

20. A segment joint, comprising: the segment bonded body has a plurality of rectangular parallelepiped honeycomb structure segments whose side surfaces are bonded to each other via a bonding material, Each of the plurality of rectangular parallelepiped honeycomb structure segments has a first segment side surface, a second segment side surface, a third segment side surface, a fourth segment side surface, a first segment bottom surface, and a second segment bottom surface, and also has porous ceramic partition walls that define a plurality of cells extending from the first segment bottom surface to the second segment bottom surface, In each of the plurality of rectangular parallelepiped honeycomb structure segments, when the maximum bending amount among the bending amounts of the first segment side surface, the second segment side surface, the third segment side surface, and the fourth segment side surface used to join adjacent honeycomb structure segments is defined as Smax (unit: mm), and the length of the line segment connecting the center of gravity of the bottom surface of the first segment and the center of gravity of the bottom surface of the second segment is defined as L (unit: mm), Smax / L≦0.010 is satisfied, 30% or more of the total number of the plurality of rectangular parallelepiped honeycomb structure segments, the sides of which are joined to each other via a bonding material, have the same orientation of the side surfaces having the maximum amount of bending. Segmental junction.

21. A segment joint as described in Claim 20, wherein the orientation of the side having the maximum amount of bending is consistent for all of the multiple rectangular honeycomb structure segments whose sides are joined to each other via bonding material.

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