JP5501631B2 - Honeycomb structure - Google Patents

Description

  The present invention relates to a honeycomb structure, and more particularly to a honeycomb structure that is prevented from being displaced in a can when stored in a can and has excellent thermal shock resistance.

  Exhaust gas regulations are becoming stricter, catalysts used for exhaust gas purification are required to have higher performance, and porous ceramic honeycomb structures that are the base of the catalyst are increasingly required to be thinner. Yes. The reason is that a honeycomb structure having a large opening diameter and a high opening ratio is desired in order to reduce pressure loss and minimize output loss (increase horsepower). In order to increase the purification performance by increasing the amount, it is desired that the light weight is desired, and that the honeycomb structure having a large surface area of the partition walls supporting the catalyst is desired.

  Among these, in order to “increase the opening diameter”, the cell density may be reduced, but in such a case, there is a reciprocal characteristic that the “surface area” which is the other requirement is also reduced. There is thinning of the structure.

  When the honeycomb structure has a thin wall, the mechanical strength is inevitably lowered. Therefore, a taper holding structure is disclosed that enables mechanical holding even at low strength (see, for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 48-1000037 JP 2008-88952 A

  When a catalyst is supported on a ceramic honeycomb structure and used as a honeycomb catalyst body, the catalyst is normally supported on all cells of the honeycomb structure and exhaust gas is allowed to pass through all the cells. Are used. Therefore, normally, the fracture pressure on the side surface of the honeycomb structure (honeycomb catalyst body) becomes the mechanical strength of the honeycomb structure (honeycomb catalyst body) itself. In contrast to the conventional structure which is held only on the side surface and all the holding force is directed from the outer periphery toward the central axis direction etc., the honeycomb structure to which the tapered holding structure is applied is the cell extending direction. The holding power is also dispersed in the (exhaust gas distribution direction). The structure is particularly suitable for a thin-walled honeycomb or the like that has low side strength and cannot be held only by the side.

  Catalytic converters formed by holding a ceramic honeycomb catalyst body in a can body (container) may loosen the grip due to severe vibrations of an automobile, and are usually made of stainless steel whose thermal expansion coefficient is 10 times that of ceramics. Since the can body is formed, if the temperature rises during use, the can body may expand larger than the ceramic honeycomb structure, and the holding of the ceramic honeycomb structure may be loosened. As described above, in order to prevent the holding of the ceramic honeycomb structure from being loosened, the honeycomb structure and the can can be prevented from moving by moving the honeycomb structure even when the can is thermally expanded. It is necessary to hold the ceramic honeycomb structure by applying high pressure in advance to the elastic mat placed between the bodies. However, in the case of a ceramic honeycomb structure in which the thickness of the partition wall is less than 0.1 mm, when it is gripped at such a high pressure, it may be broken by the pressure. On the other hand, the strength of the ceramic honeycomb structure in the cell extending direction is 5 times or more the strength of the side surface (strength when a force is applied to the side surface in the direction of the central axis). When the cells near the outer periphery (near the side surfaces) are deformed, the strength of the side surfaces tends to decrease. However, the strength in the cell extending direction is hardly affected by such cell deformation. Thus, even in a ceramic honeycomb structure having low side strength, not only side holding (holding a force in a direction perpendicular to the cells) but also “the cell extending direction” (5 times or more higher than the side strength) ( By sharing a part of the holding force also in the direction parallel to the cell), it is possible to withstand severe vibrations of the automobile.

  In Patent Document 1, a ceramic cylinder (6) having a tapered side surface is arranged on the outer periphery (side surface) of a cylindrical ceramic honeycomb structure (the cross-sectional size and the cell size are uniform). An installed structure is disclosed. This is because even if the material of the ceramic cylinder is the same cordierite as the material of the honeycomb structure, the thermal expansion coefficient of the ceramic cylinder is larger than the thermal expansion coefficient of the honeycomb structure manufactured by extrusion molding. There was a problem that cracks were likely to occur. Note that the thermal expansion coefficient of the ceramic honeycomb structure manufactured by extrusion molding is small because the extrusion raw material containing the ceramic is pressed when the ceramic honeycomb structure is extruded. Since it is formed into a honeycomb shape while being discharged through a narrow slit, the ceramic in the extruded raw material is oriented in a certain direction, thereby reducing the thermal expansion coefficient. Therefore, even when the ceramic raw material is the same, the partition wall formed by passing through such a narrow slit in a pressurized state and the cylindrical ceramic formed by other methods have different thermal expansion coefficients. It is.

This point will be explained in more detail. When unfired kaolin is used as the raw material for the honeycomb structure, the hexagonal plate-shaped crystal kaolinite of unfired kaolin is parallel to the partition walls when passing through the die for extrusion molding. line up. When fired, hexagonal cordierite crystal lays along the kaolinite crystal (the central axis of the hexagonal cordierite crystal is parallel to the hexagonal crystal plane of the kaolinite crystal) Is generated. Therefore, the central axis of the hexagonal columnar cordierite crystal has an orientation in which the cell extending direction and the radial direction of the honeycomb structure are mixed. The thermal expansion coefficient of the hexagonal columnar cordierite crystal is “−1.1 × 10 ⁻⁶ ” in the axial direction of the hexagonal column and “+ 2.9 × 10 ⁻⁶ ” in the radial direction (right angle direction). Therefore, the thermal expansion coefficient of the entire honeycomb structure is 0.2 × 10 ^{−6 to} 0.5 × 10 ⁻⁶ . This coefficient of thermal expansion is much lower than that of a honeycomb structure manufactured by another manufacturing method such as a honeycomb structure manufactured by a press manufacturing method. On the other hand, when a ceramic cylinder having a thickness of about 3 mm to be disposed on the outer periphery of a cylindrical honeycomb structure is produced by extrusion molding, the crystal orientation becomes very small. The thermal expansion coefficient is about 5 times that of the honeycomb structure (1.0 × 10 ^{−6 to} 2.0 × 10 ⁻⁶ ). It will be a big thing.

  In Patent Document 2, a cylindrical outer cylinder partly tapered is fixed to the outer periphery (side surface) of a cylindrical honeycomb structure (the cross-sectional size and the cell size are uniform). The resulting structure is disclosed. Even if the material of the outer cylinder is the same as the material of the honeycomb structure, the thermal expansion coefficient of the outer cylinder is larger than the thermal expansion coefficient of the honeycomb structure.

  The present invention has been made in view of such problems of the prior art, and provides a honeycomb structure excellent in thermal shock resistance by preventing displacement in the can when stored in the can. It is characterized by.

  The following honeycomb structure is provided by the present invention.

[1] A honeycomb-shaped porous base material having a porous partition wall mainly composed of ceramic, which defines a plurality of cells penetrating from one end face to the other end face and serving as a fluid flow path; The ceramic is disposed on the outer periphery of the base material, and has at least one end face that has a tapered shape whose outer diameter becomes narrower toward the tip, and is formed with two or more vertical slits extending parallel to the cell extending direction. and a displacement preventing member composed mainly, the vertical width of the slit is 0.5 to 10 mm, the Ri thickness of anti-displacement member 2~15mm der, the vertical formed on the anti-displacement member radial depth of the slit is the same as the thickness of the anti-displacement member, the honeycomb structure wherein the vertical that have a slit portion to expose the outer periphery of the porous substrate (the first invention).

[2] The honeycomb structure according to [1], wherein the vertical slits formed in the deviation preventing member are 4 to 8 at regular intervals.

[3] In a cross section orthogonal to the cell extending direction, the shape of the cell is a square, and at least one position of the vertical slits formed in the deviation preventing member is the position of the porous substrate. The honeycomb structure according to [1] or [2], which is a position through which a straight line extending in parallel from the center to the partition wall passes.

[4] In a cross section perpendicular to the cell extending direction, the shape of the cell is square, and at least one position of the vertical slits formed in the deviation preventing member is the position of the porous substrate. The honeycomb structure according to [1] or [2], which is a position through which a straight line extending parallel to a diagonal line of the square cell passes from the center.

[ 5 ] A honeycomb-shaped porous substrate having ceramic porous partition walls, which defines a plurality of cells penetrating from one end surface to the other end surface and serving as a fluid flow path, and an outer periphery of the porous substrate The main component is a ceramic in which at least one end face has a tapered shape with an outer diameter narrowing toward the tip, and has two or more ring slits that circulate at right angles to the cell extending direction. and a displacement preventing member which, the width of the ring slit is is 0.5 to 10 mm, the Ri thickness 2~15mm der misalignment preventing member, radial direction of the slit formed in the anti-displacement member A honeycomb structure in which the depth of the same is the same as the thickness of the deviation preventing member, and the outer periphery of the porous substrate is exposed from the slit portion (second invention).

[ 6 ] The honeycomb structure according to [ 5] , wherein the position of the ring slit formed in the deviation prevention member is a position where the deviation prevention member is equally divided.

[ 7 ] The honeycomb structure according to [ 5] or [6], wherein the shift preventing member is formed with two or more vertical slits extending in parallel with the cell extending direction.

  In the honeycomb structure of the present invention, at least one end surface of the slip prevention member has a tapered shape in which the outer diameter becomes narrower toward the tip, so that the tapered portion is mechanically fixed when housed in the can body. In the honeycomb structure capable of preventing displacement in the can, the displacement preventing member circulates at least two vertical slits extending parallel to the cell extending direction and / or perpendicular to the cell 3 extending direction. Since one or more ring slits are provided, the stress applied to the porous base material due to the difference in thermal expansion coefficient between the porous base material and the slip prevention member is relieved, so that the thermal shock resistance is excellent.

1 is a plan view schematically showing one embodiment of a honeycomb structure (first invention) of the present invention. 1 is a front view schematically showing an embodiment of a honeycomb structure (first invention) of the present invention. FIG. 6 is a plan view schematically showing a conventional honeycomb structure. FIG. 6 is a front view schematically showing a conventional honeycomb structure. FIG. 6 is a plan view schematically showing a conventional honeycomb structure. FIG. 6 is a front view schematically showing a conventional honeycomb structure. It is a top view which shows typically one Embodiment of the honeycomb structure of this invention (2nd invention). Fig. 3 is a front view schematically showing one embodiment of a honeycomb structure (second invention) of the present invention. FIG. 6 is a plan view schematically showing another embodiment of a honeycomb structure (second invention) of the present invention. FIG. 6 is a front view schematically showing another embodiment of a honeycomb structure (second invention) of the present invention. It is a graph which shows the relationship between the thermal shock resistance measured in Examples 1-5 and Comparative Examples 1-4, and the number of the vertical slits formed in the honeycomb structure. It is a graph which shows the relationship between the thermal shock resistance measured in Examples 6-10 and Comparative Examples 5-8, and the number of the vertical slits formed in the honeycomb structure.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the following embodiments, and is within the scope of the present invention. It should be understood that design changes, improvements, and the like can be made as appropriate based on the general knowledge of vendors.

(1) Honeycomb structure:
As shown in FIG. 1A and FIG. 1B, one embodiment of the honeycomb structure (first invention) of the present invention is a plurality of cells that penetrate from one end surface 1 to the other end surface 2 and serve as fluid flow paths. 3 is formed in a honeycomb-shaped porous base material 5 having porous partition walls 4 mainly composed of ceramic, and the outer periphery 6 of the porous base material 5. It has a taper shape with an outer diameter narrowing toward the tip 13 and includes a displacement prevention member 11 mainly composed of ceramic, in which four vertical slits 14 extending in parallel with the cell 3 extending direction are formed. The honeycomb structure of the present embodiment has a tapered shape in which at least one end face 12 of the slip prevention member 11 has a tapered outer diameter that decreases toward the distal end 13. Can be mechanically fixed, and it is possible to prevent slurling in the can. Further, in the honeycomb structure of the present embodiment, since the displacement prevention member has two or more vertical slits extending in parallel with the cell extending direction, the porous structure and the displacement prevention member are porous due to the difference in thermal expansion coefficient. Since the stress applied to the base material is relieved, the thermal shock resistance is excellent. FIG. 1A is a plan view schematically showing an embodiment of the honeycomb structure of the present invention. FIG. 1B is a front view schematically showing one embodiment of the honeycomb structure of the present invention. The honeycomb structure may be broken by thermal shock in a case where a crack is generated in the extending direction of the cells 3 or a ring-shaped case that circulates at right angles to the extending direction of the cells 3. In the former case, a vertical slit is effective, and in the latter case, a ring slit is effective. In each case, it is important to provide a slit in the same direction as the crack so as to avoid the position where the crack occurs so that the displacement prevention member does not become long in the direction perpendicular to the crack direction. When the ratio “H / d” of the outer diameter d and the total length H of the porous substrate is 1 or less, the vertical slit is often effective, and when the ratio exceeds 1.5, the ring slit is often effective.

  In the honeycomb structure 100 of the present embodiment, the displacement preventing member 11 only needs to have at least one end face 12 having a tapered shape. The taper angle of the displacement preventing member 11 is preferably 30 to 90 °, and more preferably 45 to 60 °. If the angle is smaller than 30 °, the shared holding force in the cell extending direction becomes small, the effect of preventing displacement when the honeycomb structured body is stored in the can body is reduced, or the shared pressure on the side surface is increased and the honeycomb structured body becomes May destroy. If it is larger than 90 °, the outer cylinder may be chipped. The taper angle of the displacement preventing member 11 is an angle formed by the end face of the displacement preventing member 11 and the outer periphery 6 of the porous substrate 5, and is the angle of the tip portion of the displacement preventing member 11. Further, the tips 13 and 13 of the taper-shaped end faces 12 and 12 of the deviation preventing member 11 in the central axis direction are separated from the end faces 1 and 2 of the porous base material 5, and one of the outer circumferences 6 of the porous base material 5. The part is exposed.

  Two or more vertical slits 14 are formed in the displacement preventing member 11, and it is preferable that 4 to 8 vertical slits are formed. If the number of the vertical slits 14 is less than 2, the effect of improving the thermal shock resistance may be reduced. Further, when the number of the vertical slits 14 exceeds 8, the compression of the mat entering between the honeycomb structure and the can body is weakened, and there is a concern that the mat may be scattered.

  In the honeycomb structure 100 of the present embodiment, the depth in the radial direction of the vertical slit 14 formed in the deviation preventing member 11 is the same as the thickness of the deviation preventing member 11, and the porous base material extends from the vertical slit 14 portion. The outer periphery 6 of 5 is exposed. By forming in this way, the thermal shock resistance can be further improved. The depth of the vertical slit 14 is preferably not less than two-thirds of the thickness of the deviation preventing member and not more than the thickness of the deviation preventing member 11. If it is shallower than two thirds of the thickness of the displacement preventing member, the effect of improving the thermal shock resistance may be reduced.

  Further, in the honeycomb structure 100 of the present embodiment, the vertical slit 14 is formed from one end surface of the deviation preventing member 11 to the other end surface. Thus, since the vertical slit 14 is formed in the whole between the both end surfaces 12 and 12 of the slip prevention member 11, it becomes possible to improve a thermal shock resistance more. The vertical slits 14 are preferably 50% or more of the length of the anti-slip member 11 in the direction in which the cells 5 extend (the length between both end faces 12, 12). If it is shorter than 50%, the effect of improving the thermal shock resistance may be reduced.

  Further, in the honeycomb structure 100 of the present embodiment, the width of the vertical slit 14 (the length in the circumferential direction of the porous base material 5) is preferably 0.5 to 10 mm, and preferably 2 to 5 mm. Further preferred. If it is narrower than 0.5 mm, the effect of improving the thermal shock resistance may be reduced. When the width is larger than 10 mm, the mat is weakly compressed and the mat may be scattered.

  Further, in the honeycomb structure 100 of the present embodiment, the displacement prevention member 11 is divided into four by four vertical slits 14. In this structure, in a cross section perpendicular to the extending direction of the cells 3, four arc-shaped ceramic walls having a predetermined thickness are provided on the outer periphery of the porous base material 5 with a gap corresponding to the width of the vertical slit 14. It can be said that the structure is open and arranged. That is, in the honeycomb structure of the present invention, in the cross section orthogonal to the cell extending direction, the arc-shaped ceramic wall along the outer periphery of the porous substrate has a gap 2 on the outer periphery of the porous substrate. It can be said that the structure is one or more. Then, at least one end face of the ceramic wall in the cell extending direction is formed in a tapered shape.

  2-15 mm is preferable and, as for the thickness of the slip prevention member 11, 3-10 mm is still more preferable. By forming in this way, it is possible to effectively prevent deviation when the honeycomb structure is stored in the can body.

  The material of the slip prevention member 11 is preferably the same as the material of the porous substrate 5. Thereby, the thermal shock resistance can be further improved.

  In the honeycomb structure 100 of the present embodiment, the porous substrate 5 has an average pore diameter of the partition walls 4 of preferably 0.5 to 10 μm, and more preferably 2 to 6 μm. If it is smaller than 0.5 μm, it is difficult to support the catalyst carrier, and if it is larger than 10 μm, the mechanical strength may be lowered. The average pore diameter of the partition walls 4 is a value measured with a mercury porosimeter.

  The porosity of the partition walls 4 is preferably 20 to 45%, and more preferably 25 to 40% from the viewpoint of ease of production. If it is less than 20%, the catalyst carrier becomes difficult to be supported, and shrinkage during firing may increase, resulting in a large dimensional variation. If it exceeds 45%, the mechanical strength may decrease. There is. The porosity of the partition 4 is a value measured with a mercury porosimeter.

  The shape of the cell 3 of the porous substrate 5 is not particularly limited, but in the cross section orthogonal to the cell extending direction (center axis), it is a polygon such as a triangle, a rectangle, a pentagon, a hexagon, a circle, or an ellipse. Preferably, it may be indefinite. Of the quadrangles, a square is preferable. Moreover, it is preferable that the size of the cross section orthogonal to the central axis of each cell 3 formed on the porous substrate 5 is the same from one end to the other end. Thereby, a stable product can be obtained.

  In the honeycomb structure 100 of the present embodiment, when the shape of the cell 3 of the porous substrate 5 is a square in the cross section orthogonal to the cell extending direction, at least one of the vertical slits 14 formed in the deviation preventing member 11. One position is preferably a position where a straight line extending “in parallel with the partition wall” passes from the center of the porous substrate 5, and all the vertical slits 14 are positioned from the center of the porous substrate 5 to “ It is preferably a position where a straight line extending parallel to the partition wall passes. There are four such positions on the misalignment prevention member 11, and it is preferable that a predetermined number of vertical slits are located in any of these four places. Thereby, the thermal shock resistance can be further improved. In this case, a sufficiently high effect can be obtained by setting the number of vertical slits to two, and it is more preferable if the number is more. Further, the position of at least one of the vertical slits may be a position where a straight line extending in parallel to the “diagonal line of the square cell” passes, and the positions of all the vertical slits may be “the diagonal line of the square cell. It may be a position through which a straight line extending in parallel with When all the vertical slits are located at a position where a straight line extending in parallel with the “diagonal line of the square cell” passes, it is preferable to use four vertical slits. In this case, if there are two or three vertical slits, the effect of improving the thermal shock resistance may be small. When the position of the vertical slit 14 is a position through which a straight line extending “in parallel with the partition wall” passes from the center of the porous substrate 5, the position of the vertical slit 14 is changed from the center of the porous substrate 5 to “a square cell. More preferably, it is a position through which a straight line extending in parallel with the "diagonal line" passes. The position of the vertical slit 14 is a position through which a straight line extending in parallel to the “diagonal line of the square cell” passes from the center of the porous substrate 5 ”means that the vertical slit 14 is from the center of the porous substrate 5. It means to be located on a straight line extending in parallel to the “diagonal line of the square cell”. There are four such positions on the misalignment prevention member 11, and it is preferable that a predetermined number of vertical slits are located in any of these four places. Moreover, the vertical slit located on the straight line extended in parallel with the "diagonal line of the square cell" from the center of the porous base material 5, and the vertical slit which is not located on the said straight line may be formed. When five or more vertical slits are formed, the vertical slits extend in parallel to the position where a straight line extending from the center of the porous substrate 5 to “parallel to the partition wall” passes and “diagonal lines of square cells”. It is preferable that the position is one of the positions through which the straight line passes. For example, four vertical slits are formed at a position where a straight line extending “in parallel with the partition wall” passes from the center of the porous substrate 5, and the remaining vertical slits are “square cells” from the center of the porous substrate 5. The aspect formed in the position where the straight line extended in parallel with the "diagonal line of" passes is a preferable aspect. Four vertical slits are formed at a position where a straight line extending in parallel to the “diagonal line of the square cell” passes from the center of the porous substrate 5, and the remaining vertical slits are formed from the center of the porous substrate 5. An embodiment in which a straight line extending in “parallel to the partition walls” passes is also a preferred embodiment.

  The porous substrate 5 (partition wall 4) is mainly composed of ceramic. Specifically, the material of the partition 4 is silicon carbide, cordierite, alumina titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, silica, and LAS (lithium aluminum silicate) or these. What combined these can be mentioned as a suitable example. In particular, ceramics such as silicon carbide, cordierite, mullite, silicon nitride, alumina, and alumina titanate are suitable in terms of alkali resistance. Among these, oxide-based ceramics are preferable in terms of cost. In addition, the phrase “having ceramic as a main component” means that 90% by mass or more of a ceramic crystal referred to is contained. The rest of the components other than ceramics are not particularly limited, and examples thereof include glass.

  Although the magnitude | size of the porous base material 5 is not specifically limited, It is preferable that the length of the cell extension direction (center axis direction) is 50-500 mm. Moreover, when the cross-sectional shape orthogonal to the cell extending direction is circular, the diameter is preferably 50 to 350 mm.

  In the honeycomb structure of the present invention (second invention), in the above-described honeycomb structure of the present invention (first invention), the slip prevention member is formed with a ring slit that circulates at right angles to the cell extending direction. It is a thing. The misalignment prevention member does not need to have a vertical slit, but is preferably formed. According to a second aspect of the present invention, there is provided a first anti-shift member, except that a ring slit that circulates at right angles to a cell extending direction and a vertical slit may or may not be formed. It is the structure similar to invention.

  One embodiment (honeycomb structure 103) of the honeycomb structure (second invention) of the present invention is one embodiment of the honeycomb structure of the first invention as shown in FIGS. 4A and 4B. The vertical slits 31 are provided on the anti-shift member 11 so as to circulate at right angles to the direction in which the cells 3 extend without the vertical slit being formed on the anti-shift member 11. The number of ring slits is preferably 1 to 3. The width and depth of the ring slit are preferably in the same range as the preferred range of the width and depth of the vertical slit. FIG. 4A is a plan view schematically showing one embodiment of the honeycomb structure (second invention) of the present invention. FIG. 4B is a front view schematically showing one embodiment of the honeycomb structure (second invention) of the present invention. In addition, in one embodiment of the honeycomb structure of the present invention (second invention) shown in FIGS. 4A and 4B, the constituent elements constituting one embodiment of the honeycomb structure of the present invention (first invention) The same constituent elements as those in FIG. 1A and FIG. 1B according to the embodiment of the honeycomb structure of the present invention (first invention) are denoted by the same reference numerals. Yes.

  In another embodiment (honeycomb structure 104) of the honeycomb structure (second invention) of the present invention, both the vertical slit 14 and the ring slit 31 are provided simultaneously. The configuration of the vertical slit 14 is preferably the same as that of the above-described honeycomb structure of the present invention (first invention). FIG. 5A is a plan view schematically showing another embodiment of the honeycomb structure (second invention) of the present invention. FIG. 5B is a front view schematically showing another embodiment of the honeycomb structure (second invention) of the present invention.

(2) Manufacturing method of honeycomb structure:
Next, a method for manufacturing an embodiment of the honeycomb structure of the present invention (first invention) will be described.

  A honeycomb formed body having a partition wall that partitions a plurality of cells that penetrate from one end face to the other end face and serve as a fluid flow path is formed by extrusion. The method for extruding the honeycomb formed body is not particularly limited.For example, the forming raw material is first kneaded to form a kneaded material, and the obtained kneaded material is formed into a honeycomb shape by extrusion forming to obtain a honeycomb formed body. preferable. There is no restriction | limiting in particular as a method of kneading | mixing a shaping | molding raw material and forming a clay, For example, the method of using a kneader, a vacuum clay kneader, etc. can be mentioned. Extrusion molding is preferably performed using a die having a desired cell shape, partition wall thickness, and cell density. As the material of the die, a cemented carbide which does not easily wear is preferable.

  The forming raw material is obtained by adding a dispersion medium and an additive to a ceramic raw material, and examples of the additive include an organic binder, an inorganic binder, a pore former, and a surfactant. As the forming raw material, it is preferable that the material for the partition walls mentioned in the embodiment of the honeycomb structure of the present invention is formed by firing.

  By adjusting the particle size and blending amount of the ceramic raw material to be used and the particle size and blending amount of the pore former to be added and optimizing the firing conditions, a porous substrate having a desired porosity and average pore size can be obtained. Can be obtained.

  After the above forming, the obtained honeycomb formed body may be dried. The drying method is not particularly limited, and examples thereof include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying and the like. Among them, dielectric drying, microwave drying or It is preferable to perform hot air drying alone or in combination. The drying conditions are preferably a drying temperature of 30 to 150 ° C. and a drying time of 1 minute to 2 hours.

  Next, it is preferable to fire the honeycomb formed body to obtain a porous substrate. Since the firing conditions (temperature, time) vary depending on the type of the forming raw material, an appropriate condition may be selected according to the type.

  Next, it is preferable to apply a ceramic cement to the outer periphery of the porous substrate and dry it to form a porous substrate with an outer cylinder. The porous base material with an outer cylinder has a structure in which an outer cylinder made of ceramic cement is disposed on the outer periphery of the porous base material. The ceramic cement is preferably a mixture of colloidal silica and ceramic (powder) that is a material of the porous substrate. For example, when the material of the porous substrate is cordierite, it is preferable to use a ceramic cement obtained by mixing cordierite powder with colloidal silica.

  Next, it is preferable to obtain the honeycomb structure of the present invention by tapering the end surface of the outer tube of the porous base material with the outer tube and slitting the side surface of the outer tube. The method of taper processing is not particularly limited, but, for example, a method of pressing a grindstone coated with diamond having a predetermined taper shape while rotating a porous base material with an outer cylinder is preferable. Thereby, taper processing can be performed easily and quickly in about 10 seconds. Moreover, although the method of slit processing is not specifically limited, For example, the method of rotating and processing a thin-toothed grindstone is preferable. In addition, after apply | coating a ceramic cement to the outer periphery of a porous base material, a taper process may be performed and a ceramic cement may be dried after that. Moreover, after apply | coating ceramic cement to the outer periphery of a porous base material, slit processing may be performed and ceramic cement may be dried after that. As a method for forming the taper and the slit before the ceramic cement is dried, a method of pressing a “mold” having a predetermined shape is preferable.

  In the manufacturing method of one embodiment of the honeycomb structure of the present invention (second invention), in the step of forming the vertical slit, a ring slit is formed instead of the vertical slit (or both the ring slit and the vertical slit are formed). Except for forming, it is the same as the manufacturing method of one embodiment of the honeycomb structure of the present invention (first invention).

(3) Honeycomb catalyst body:
The honeycomb structure of the present invention (the first and second inventions) is preferably used as a honeycomb catalyst body carrying a catalyst. The catalyst is preferably supported on the inside of the outer peripheral wall of the porous substrate, the partition wall surface in the cell, and / or the pores of the partition wall.

  The catalyst loading method can be the same as a general catalyst loading method on the honeycomb structure. Specifically, a method of supporting the catalyst by pouring a catalyst solution into the cell from one end face of the porous substrate can be mentioned. As another method, one end face of the honeycomb structure is immersed in several millimeters of catalyst solution, and the pressure is reduced from the other end face in this state, whereby the catalyst solution is sucked into the cell, and the porous substrate A method of supporting the catalyst on the partition walls in the cell of the material can be mentioned.

  After flowing the catalyst solution into the cell of the porous substrate, it is preferable to blow off excess slurry with compressed air. Thereafter, the catalyst is preferably dried and baked to obtain a honeycomb catalyst body in which the catalyst is coated (supported) on the surface of the partition walls in the cell.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
The cordierite-forming raw material from which cordierite is obtained by firing is kneaded with water and binder while vacuum degassing, and is extruded from one end face to the other end face by extrusion molding using a prescribed die. A honeycomb formed body having partition walls that partition and form a plurality of cells serving as fluid flow paths was obtained. In the cross section orthogonal to the cell extending direction, the cell shape was square.

  Next, the honeycomb formed body was dried and fired to obtain a porous substrate. Next, ceramic cement obtained by mixing cordierite powder in colloidal silica was applied to the outer periphery of the obtained porous substrate, and dried to form a porous substrate with an outer cylinder. And the both ends of the outer cylinder of the porous base material with an outer cylinder were taper-processed, and the side surface of the outer cylinder was vertical-slit-processed, and the two vertical slits were formed, and the honeycomb structure was obtained. The method of tapering is to press a grindstone coated with diamond against the outer peripheral portion of the end surface of the outer cylinder of the porous substrate at an angle of 45 ° with respect to the cell extending direction while rotating the porous substrate. Thus, a method of obtaining a tapered end face (an end face of the displacement preventing member) having an angle of 45 ° was obtained. Moreover, the method of length slit processing was made into the method of rotating a grindstone with a thin tooth. The grinding depth was set to a depth that left about 0.5 mm of the anti-slip member so as not to damage the porous substrate.

The obtained honeycomb structure had a partition wall thickness of 0.09 mm and a cell density of 62 cells / cm ² . The outer diameter (diameter) of the side surface portion of the slip prevention member was 114 mm, the outer diameter (diameter) of the porous substrate was 106 mm, and the length in the central axis direction of the porous substrate was 114.3 mm. . Further, the length in the central axis direction of the portion where the outer periphery of the porous substrate was exposed was 5 mm. With respect to the obtained honeycomb structure, “thermal shock resistance” was measured by the following method, and a “heating vibration test” was performed. The results are shown in Table 1.

  In Table 1, the “slit” column indicates the number of slits formed in the deviation preventing member. Further, the column of “slit forming position” indicates the position of the vertical slit formed in the misalignment prevention member, unless otherwise specified. Specifically, in a cross section orthogonal to the cell extending direction, a position where one straight line extending in parallel to the partition wall from the center of the porous substrate intersects with the displacement preventing member is set to a position of “0 °”. Starting from the position of “0 °”, the angle of the position where the slit is formed with respect to the position of “0 °” (the straight line connecting the center of the porous substrate and the position of “0 °” The angle rotated around the center). For example, the honeycomb structure of Example 3 is the honeycomb structure having the structure shown in FIG. 1A and FIG. 1B, and the vertical slit formation position is a “0 °” position and a 90 ° rotation from the “0 °” position. Position “90 °”, “180 °” position rotated by 180 ° from “0 °” position, and “270” position rotated by 270 ° from “0 °” position. Vertical slits are formed at four positions of “°”.

(Heat shock resistance)
The thermal shock resistance test is performed according to the procedure specified in “JASO M505-87 Section 6.7”. A room temperature sample is placed in an electric furnace maintained at a predetermined temperature and held for 20 minutes. Remove the sample and place it on a refractory brick and cool to room temperature “observing for cracks”. It should be noted that cooling the sample while observing the presence or absence of cracks is not specified in “JASO M505-87 Section 6.7”, but is an operation specific to this “thermal shock resistance test”. Thermal shock resistance is the maximum temperature difference where there is no crack when observing the appearance of the sample, and when the entire circumference is tapped with a metal rod (iron rod with a diameter of about 1 to 3 mm), the hitting sound is a metal sound. (Temperature difference from room temperature: “electric furnace temperature−room temperature”). When a crack occurs or the hitting sound is not a metallic sound, it is assumed that it is “abnormal”. The sample is a honeycomb structure with no catalyst. The initial predetermined temperature is “600 ° C. + room temperature”. If there is no abnormality, the temperature of the electric furnace is increased by 50 ° C., and the temperature is increased by 50 ° C. until an abnormality occurs. The test was repeated. Five honeycomb structures were tested, and the average value of the temperature one step lower than the temperature at which the abnormality was recognized (a temperature lower by 50 ° C. than the temperature at which the abnormality was recognized) was taken as the result of the thermal shock resistance test. Table 1 shows the “maximum temperature difference”. The maximum temperature difference is preferably not lower than Comparative Example 1 or Comparative Example 5 by 50 ° C. or more. Further, in the column of the fracture position, “T” is the vertical crack and the subsequent number is the occurrence position, “R” is the ring crack, and the position where the ring crack enters is approximately the center in the full length direction.

(Heating vibration test)
An unexpanded mat made of ceramic fibers is stored in a wound can body in a honeycomb structure. The can body has an inner diameter of a size obtained by adding the mat thickness of 0.2 MPa to the outer diameter of the outer cylinder portion of the honeycomb structure, and one end portion remains straight and the other end portion has a honeycomb. The tapered portion has the same angle as the end surface of the outer cylinder portion of the structure, and the tip of the tapered portion has a cone shape so as to have the same outer diameter as the exhaust pipe. Then, a honeycomb structure wound with a mat is inserted from the straight end portion side of the can body, and the taper portion of the honeycomb structure hits the can body taper portion and is pushed in until the mat reaches a predetermined pressure. The straight side of the can has a flange, and a “lid” is attached to the flange. The “lid” starts from a flange connected to the can body, has a tapered portion having the same shape as the tapered shape of the can body, a cone portion at the tip, and is connected to a pipe to which a high temperature gas is supplied at the tip. With a flange. The lid is pressed against the can body, and the flanges are tightened with bolts to prevent gas from leaking between the can body and the lid. The taper of the lid has a positional relationship that matches the taper of the honeycomb structure when the flanges are combined. In this state, vibration is applied from the vibration tester for 100 hours while repeating a cycle of flowing a high-temperature gas combusted with propane gas for 5 minutes and then flowing air at room temperature for 5 minutes to the cells of the honeycomb structure. The temperature of the hot gas is 900 ° C. The vibration condition is “acceleration: 30 G, frequency: 200 Hz”. After the test, when the honeycomb structure was displaced by 2 mm or more in the can, the honeycomb structure was rejected. When the displacement was less than 2 mm, the honeycomb structure was accepted. As the pass / fail judgment of the heating vibration test, two honeycomb structures were tested, and when both passed, the pass “◯” was given, and when there was at least one pass, the reject “X” was given.

(Examples 2-11, Comparative Examples 1-10)
A honeycomb was formed in the same manner as in Example 1 except that the “partition wall thickness”, “cell density”, “displacement preventing member”, “slit”, and “slit formation position” were changed as shown in Table 1. A structure was produced. About the obtained honeycomb structure, the “thermal shock resistance” was measured by the above method in the same manner as in Example 1, and the “heating vibration test” was performed. The results are shown in Table 1. The results of the thermal shock resistance test are summarized in FIGS. 6 and 7, “starting point 0 °” refers to a position where one straight line extending in parallel to the partition wall from the center of the porous substrate intersects the displacement preventing member in a cross section orthogonal to the cell extending direction. Indicates that a vertical slit is formed. In addition, the “starting point 45 °” is a vertical slit at a position where one straight line extending in parallel to the diagonal line of the rectangular cell from the center of the porous base material intersects with the displacement preventing member in a cross section orthogonal to the cell extending direction. Is formed. “No ceramic cylinder” indicates that the honeycomb structure does not include a displacement prevention member. FIG. 6 is a graph showing the relationship between the thermal shock resistance measured in Examples and the number of vertical slits formed in the honeycomb structure. FIG. 7 is a graph showing the relationship between the thermal shock resistance measured in Examples and the number of vertical slits formed in the honeycomb structure. FIG. 6 shows the results for a honeycomb structure with a partition wall thickness of 0.09 mm and a cell density of 62 cells / cm ² , and FIG. 7 shows a honeycomb structure with a partition wall thickness of 0.064 mm and a cell density of 93 cells / cm ^2. The result about is shown.

  In addition, the outer diameter (diameter) of the side surface part of the slip prevention member of Comparative Examples 9 and 10 and Example 11 is 94 mm, and the outer diameter (diameter) of the porous substrate is 86 mm. The length in the central axis direction was 160 mm. Further, the length in the central axis direction of the portion where the outer periphery of the porous substrate was exposed was 5 mm.

  Further, the honeycomb structures of Comparative Examples 1, 5, and 9 have a structure like the honeycomb structure 101 shown in FIGS. 2A and 2B. The honeycomb structure 101 has a honeycomb-shaped porous base material 21 having porous partition walls mainly composed of ceramic, which partition and form a plurality of cells that penetrate from one end face to the other end face and serve as fluid flow paths. It is a honeycomb structure provided with. FIG. 2A is a plan view schematically showing a conventional honeycomb structure. FIG. 2B is a front view schematically showing a conventional honeycomb structure.

  Further, the honeycomb structures of Comparative Examples 2, 6, and 10 have a structure like the honeycomb structure 102 shown in FIGS. 3A and 3B. The honeycomb structure 102 has a honeycomb-shaped porous base material 22 having porous partition walls mainly composed of ceramic, which partition and form a plurality of cells that penetrate from one end face to the other end face and serve as fluid flow paths. And a displacement preventing member 23 disposed on the outer periphery of the porous base material 22 and having both end faces tapered. The slits 23 are not formed with slits. FIG. 3A is a plan view schematically showing a conventional honeycomb structure. FIG. 3B is a front view schematically showing a conventional honeycomb structure.

  Further, the honeycomb structure of Example 11 has a structure like the honeycomb structure 103 shown in FIGS. 4A and 4B. The honeycomb structure 103 has a honeycomb-shaped porous substrate 5 having porous partition walls mainly composed of ceramic, which form a plurality of cells penetrating from one end face to the other end face and serving as fluid flow paths. And a displacement prevention member 11 disposed on the outer periphery of the porous substrate 5 and having both end faces tapered. A ring slit 31 is formed in the slip prevention material 11.

  Table 1 shows that the honeycomb structures of Examples 1 to 11 are excellent in thermal shock resistance and the result of the heat vibration test is good when compared for each cell structure. On the other hand, it can be seen that the honeycomb structures of Comparative Examples 2-4 and 6-8 are inferior in thermal shock resistance. However, in Example 2, the difference is less than 50 °, which is 60 ° lower than that of Comparative Example 1, and is less effective, while in Example 7, the difference which is 40 ° lower than that of Comparative Example 5 is less than 50 °. . Since Comparative Example 1 and Comparative Example 5, which are originally normal honeycomb structures, have cracks in the 45 ° direction, it can be seen that four or more slits are necessary when slitting at 45 °. And it turns out that the result of a heating vibration test is bad about the honeycomb structure of Comparative Examples 1 and 5.

  The honeycomb structure of the present invention is suitably used as a base of a catalyst used for exhaust gas purification.

1: one end surface, 2: other end surface, 3: cell, 4: partition, 5: porous substrate, 6: outer periphery of porous substrate, 11: displacement preventing member, 12: end surface, 13: tip, 14: Vertical slit, 21, 22: Porous base material, 23: Displacement preventing member, 31: Ring slit, 100, 101, 102, 103, 104: Honeycomb structure.

Claims (7)

A honeycomb-shaped porous base material having a porous partition wall mainly composed of ceramic, which defines a plurality of cells penetrating from one end face to the other end face and serving as a fluid flow path;
Arranged on the outer periphery of the porous base material, at least one end face has a tapered shape with an outer diameter decreasing toward the tip, and two or more vertical slits extending in parallel with the cell extending direction are formed. It is provided with a slip prevention member mainly composed of ceramic,
The width of the vertical slit is 0.5 to 10 mm, the thickness of the anti-displacement member Ri 2~15mm der,
Radial depth of the vertical slit formed in the anti-displacement member is the same as the thickness of the anti-displacement member, the honeycomb structure wherein the vertical that have a slit portion to expose the outer periphery of the porous substrate .   The honeycomb structure according to claim 1, wherein the number of the vertical slits formed in the deviation preventing member is 4 to 8 at regular intervals.   In the cross section orthogonal to the cell extending direction, the shape of the cell is a square, and at least one position of the vertical slits formed in the deviation preventing member is from the center of the porous substrate. The honeycomb structure according to claim 1 or 2, which is a position where a straight line extending in parallel with the partition wall passes.   In the cross section orthogonal to the cell extending direction, the shape of the cell is a square, and at least one position of the vertical slits formed in the deviation preventing member is from the center of the porous substrate. The honeycomb structure according to claim 1 or 2, which is a position through which a straight line extending in parallel with a diagonal line of a square cell passes. A honeycomb-shaped porous base material having a ceramic porous partition wall, which partitions a plurality of cells that penetrate from one end face to the other end face and serve as a fluid flow path, and is disposed on the outer periphery of the porous base material And at least one end face is tapered so that the outer diameter becomes narrower toward the tip, and the main component is prevention of misalignment composed mainly of ceramics in which two or more ring slits are formed that circulate at right angles to the cell extending direction. With members,
The width of the ring slit is 0.5 to 10 mm, the thickness of the anti-displacement member Ri 2~15mm der,
A honeycomb structure in which a radial depth of the slit formed in the deviation preventing member is the same as a thickness of the deviation preventing member, and an outer periphery of the porous substrate is exposed from the slit portion . The honeycomb structure according to claim 5 , wherein the position of the ring slit formed in the deviation preventing member is a position where the deviation preventing member is equally divided. The honeycomb structure according to claim 5 or 6 , wherein two or more vertical slits extending in parallel with the cell extending direction are formed in the shift preventing member.

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