WO2020075605A1 - Honeycomb structure - Google Patents

Honeycomb structure Download PDF

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Publication number
WO2020075605A1
WO2020075605A1 PCT/JP2019/039041 JP2019039041W WO2020075605A1 WO 2020075605 A1 WO2020075605 A1 WO 2020075605A1 JP 2019039041 W JP2019039041 W JP 2019039041W WO 2020075605 A1 WO2020075605 A1 WO 2020075605A1
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Prior art keywords
exhaust gas
honeycomb structure
cell
porosity
honeycomb
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PCT/JP2019/039041
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French (fr)
Japanese (ja)
Inventor
郁仁 手嶋
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イビデン株式会社
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Publication of WO2020075605A1 publication Critical patent/WO2020075605A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01J35/56—

Definitions

  • the present invention relates to a honeycomb structure.
  • the exhaust gas discharged from an internal combustion engine such as a gasoline engine or a diesel engine contains particulates such as soot (hereinafter, also referred to as PM), and in recent years, this PM may be harmful to the environment or the human body. It's a problem. Moreover, since harmful gas components such as CO, HC or NOx are also contained in the exhaust gas, there is concern about the effect of these harmful gas components on the environment or the human body.
  • titanic acid is used as an exhaust gas purifying apparatus for collecting PM in exhaust gas by connecting with an internal combustion engine and purifying harmful gas components such as CO, HC or NOx contained in the exhaust gas.
  • Various honeycomb structures made of porous ceramics such as aluminum, cordierite, and silicon carbide have been proposed.
  • Patent Document 1 has a plurality of first flow paths that are open at one end surface and closed at the other end surface, and a plurality of second flow paths that are closed at the one end surface and open at the other end surface.
  • a central partition wall in which the cross-sectional area of each of the first flow paths and the second flow path is constant in the axial direction, and a cross-sectional area of each of the first flow paths from the central partition wall toward the other end surface.
  • a honeycomb structure including: the other end side inclined partition wall, which is reduced and has a larger cross-sectional area of each of the second flow paths, wherein the other end side inclined partition wall has an axial length of 4 mm or more.
  • a honeycomb structure is disclosed.
  • Patent Document 1 describes that the porosity of the partition walls of the honeycomb structure can be 40 to 70%, and there is no other description regarding the porosity, and therefore Patent Document 1 In the honeycomb structure described in (1), it is considered that the partition walls had the same porosity as a whole without changing the porosity at a specific portion.
  • the inclined partition walls cannot be used sufficiently as a PM trapping area, and a honeycomb structure having a lower pressure loss is required.
  • a method for improving the gas permeability in order to reduce the pressure loss of the honeycomb structure a method of increasing the overall porosity by changing the material composition and firing conditions can be considered.
  • the present invention has been made in view of such a problem, and an object thereof is to provide a honeycomb structure having a low pressure loss without deteriorating the mechanical characteristics.
  • the honeycomb structure of the present invention is a porous cell partition wall that partitions and forms a plurality of cells that are channels of exhaust gas, and an exhaust gas introduction cell in which the end surface on the exhaust gas inlet side is opened and the end surface on the exhaust gas outlet side is closed.
  • honeycomb structure including an exhaust gas discharge cell in which an end surface on the exhaust gas outlet side is opened and an end surface on the exhaust gas inlet side is sealed,
  • the porosity in the end region is higher than the porosity in the inner region.
  • the end face of the exhaust gas introduction cell on the exhaust gas outlet side and the end face of the exhaust gas discharge cell on the exhaust gas inlet side are sealed by filling a part including the end face with a sealant. Rather than being present, it means that the cross-sectional shape perpendicular to the longitudinal direction of the cell is reduced as it approaches the end face in the end region, the area of the cross section becomes 0 at the end face, and the cell is closed.
  • the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell is enlarged or reduced as it approaches the end face. Since the porosity in the end region is higher than the porosity in the inner region, the exhaust gas easily permeates the cell partition walls in the end region while maintaining the mechanical strength, and the end region is also PM. Since it can be used as a trapping area for exhaust gas, it is possible to reduce the pressure loss due to the permeation of exhaust gas into cell partition walls and the permeation of the PM layer deposited on the cell partition walls.
  • the opening ratio is high at the end faces of the exhaust gas inlet side and the outlet side, the resistance when the exhaust gas flows into the honeycomb structure and flows out from the exhaust gas structure becomes small. The pressure loss can be further reduced.
  • the porosity in the end area is 0.5 to 5% higher than the porosity in the inner area.
  • the exhaust gas permeability at the exhaust gas inlet and outlet can be further improved. Therefore, it is possible to sufficiently reduce the pressure loss due to the permeation of the exhaust gas into the cell partition walls and the permeation of the PM layer deposited on the cell partition walls while maintaining the mechanical strength.
  • the cell partition wall permeability of the exhaust gas at the inlet and the outlet is improved. If it is difficult to sufficiently improve the porosity in the end region above 5% with respect to the porosity in the inner region, the mechanical strength of the end region is reduced and The area is easily damaged.
  • the porosity of the cell partition walls in the inner region is preferably 35 to 65%.
  • the porosity of the cell partition walls in the internal region is 35 to 65%, it is possible to suppress an increase in pressure loss due to the internal region and to obtain sufficient mechanical strength. Can be maintained.
  • the porosity of the cell partition walls is less than 35%, the proportion of the pores of the cell partition walls in the inner region is too small, so that the exhaust gas is less likely to pass through the cell partition walls in the inner region and the pressure loss increases.
  • the porosity of the cell partition walls exceeds 65%, the mechanical properties of the cell partition walls in the internal region are not sufficient, and cracks are likely to occur during reproduction or the like.
  • the average pore diameter of the pores in the end region is 5 to 30 ⁇ m.
  • the average pore diameter of the pores contained in the cell partition walls is 5 to 30 ⁇ m, PM can be collected with high collection efficiency while keeping the pressure loss low.
  • the average pore diameter of the pores contained in the cell partition walls is less than 5 ⁇ m, the pores are too small, and the pressure loss when exhaust gas permeates the cell partition walls increases. On the other hand, if the average pore diameter of the pores contained in the cell partition wall exceeds 30 ⁇ m, the pore diameter becomes too large, and the PM trapping efficiency decreases.
  • the length of the cells in the end region in the longitudinal direction is preferably 1 to 10 mm.
  • the resistance at which the exhaust gas is introduced into the cells at the exhaust gas inlet side and the exhaust gas outlet side at the exhaust gas outlet side Since the resistance of the exhaust gas discharged from the inside of the cell can be further reduced, the pressure loss can be further reduced.
  • the honeycomb structure of the present invention when the length of the cells in the end region in the longitudinal direction is less than 1 mm, the resistance at the time of introducing the exhaust gas into the cells on the exhaust gas inlet side increases, and the exhaust gas outlet On the side, since the resistance when exhaust gas is discharged becomes large, it is not possible to sufficiently reduce the pressure loss. On the other hand, when the length of the cell in the end region in the longitudinal direction exceeds 10 mm, such a structure is formed. It becomes difficult to manufacture the honeycomb structure.
  • the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm.
  • the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm, the thickness of the cell partition wall is sufficiently reduced without lowering the compressive strength. Therefore, the pressure loss can be further reduced.
  • the thickness of the cell partition wall in the end region is less than 0.1 mm, the thickness of the cell partition wall becomes too thin, which lowers the compressive strength.
  • the thickness of the cell partition wall exceeds 0.5 mm, the thickness of the cell partition wall is too thick, and it becomes difficult to sufficiently reduce the pressure loss.
  • the cross-sectional shape of the cells in the inner region which is perpendicular to the longitudinal direction, be quadrangular.
  • the cross-sectional shape perpendicular to the longitudinal direction of the cells in the internal region is a quadrangle, and in manufacturing the honeycomb structure, in the end region, a cross-section perpendicular to the longitudinal direction of the cells. The shape can be easily expanded or reduced as it approaches the end face, and a honeycomb structure having a sufficiently low pressure loss can be realized.
  • the honeycomb structure of the present invention it is desirable that the honeycomb structure is made of one honeycomb fired body having an outer peripheral wall on the outer periphery.
  • the opening ratio at the end face can be increased due to the absence of the adhesive layer, so that the pressure loss reducing effect is further improved. Can be demonstrated.
  • the honeycomb fired body is preferably made of cordierite or aluminum titanate.
  • the honeycomb fired body when the honeycomb fired body is made of cordierite or aluminum titanate, since the ceramic is a material having a low coefficient of thermal expansion, when large thermal stress occurs during regeneration or the like. Even in this case, the honeycomb structure is resistant to cracks.
  • FIG. 1 (a) is a perspective view schematically showing an example of the honeycomb structure of the present invention
  • FIG. 1 (b) is a sectional view taken along the line AA in FIG. 1 (a).
  • c) is an end view as seen from one end surface side.
  • FIG. 2 (a) is a perspective view schematically showing an unsealed honeycomb molded body
  • FIG. 2 (b) is a cross section taken along line BB of the unsealed honeycomb molded body shown in FIG. 2 (a). It is a figure.
  • FIG. 3 is an explanatory view schematically showing a state of a remolding step of the unsealed honeycomb molded body.
  • FIG. 4 is a cross-sectional view schematically showing a state of a remolding step of the unsealed honeycomb molded body.
  • FIG. 5: is sectional drawing which shows the pressure loss measuring method typically.
  • the honeycomb structure of the present invention is a porous cell partition wall that partitions and forms a plurality of cells that are channels of exhaust gas, and an exhaust gas introduction cell in which an end surface on the exhaust gas inlet side is opened and an end surface on the exhaust gas outlet side is closed.
  • a honeycomb structure having an exhaust gas discharge cell in which an end face on the exhaust gas outlet side is opened and an end face on the exhaust gas inlet side is sealed, wherein the exhaust gas introducing cell and the exhaust gas discharging cell are the exhaust gas introducing cells And an inner region in which the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas discharge cell is constant, and an end where the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell is enlarged or reduced as it approaches the end surface. And a porosity in the end region is higher than a porosity in the inner region.
  • FIG. 1 (a) is a perspective view schematically showing an example of the honeycomb structure of the present invention
  • FIG. 1 (b) is a sectional view taken along the line AA in FIG. 1 (a).
  • c) is an end view as seen from one end surface side.
  • the honeycomb structure 10 shown in FIGS. 1 (a) and 1 (b) has a porous cell partition wall 11 for partitioning and forming a plurality of cells 12 and 13 serving as exhaust gas flow paths, and an end face 10a on the exhaust gas inlet side.
  • An exhaust gas introduction cell 12 that is opened and has an end face 10b on the exhaust gas outlet side sealed, and an exhaust gas discharge cell 13 that has an end face 10b on the exhaust gas outlet side opened and the end face 10a on the exhaust gas inlet side are sealed,
  • the introduction cell 12 and the exhaust gas discharge cell 13 are perpendicular to the longitudinal direction of the exhaust gas introduction cell 12 and the exhaust gas discharge cell 13 and the internal region 10B having a constant sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell 12 and the exhaust gas discharge cell 13.
  • the cross-sectional shape is enlarged or reduced as it approaches the end face, and the end regions 10A and 10C are sealed.
  • the honeycomb structure 10 is made of a single honeycomb fired body, the honeycomb fired body is also a honeycomb structure.
  • the porosity in the end regions 10A and 10C is higher than that in the inner region 10B. Therefore, it is possible to improve the permeability of the exhaust gas at the inlet and the outlet of the exhaust gas, and reduce the pressure loss due to the permeation of the exhaust gas into the cell partition walls and the permeation of the PM layer deposited on the cell partition walls while maintaining the mechanical strength. be able to.
  • the porosity in the end area is 0.5 to 5% higher than the porosity in the inner area.
  • the cell partition wall permeability of the exhaust gas can be further improved, and the mechanical strength can be improved. It is possible to sufficiently reduce the pressure loss due to the permeation of exhaust gas through the cell partition walls and the permeation of the deposited PM layer while maintaining the strength.
  • the porosity of the cell partition walls in the inner region is preferably 35 to 65%.
  • the porosity of the cell partition walls in the internal region is 35 to 65%, it is possible to suppress an increase in pressure loss due to the internal region and to obtain sufficient mechanical strength. Can be maintained.
  • the porosity of the cell partition walls in the inner region is 35 to 65%, so that the porosity in the end region is 35.5 to 70%.
  • the porosity in the end region is higher than in the inner region, but the region of high porosity is limited and continues from the inner region, so deterioration of mechanical strength is suppressed, and The pressure loss can be reduced.
  • the average pore diameter of the pores in the end region is 5 to 30 ⁇ m.
  • the porosity and the average pore diameter are measured by a mercury intrusion method under the conditions of a contact angle of 130 ° and a surface tension of 485 mN / m.
  • the length of the cells in the end region is 1 to 10 mm in the longitudinal direction.
  • the resistance at which the exhaust gas is introduced into the cells at the exhaust gas inlet side and the exhaust gas outlet side at the exhaust gas outlet side Since the resistance of the exhaust gas discharged from the inside of the cell can be further reduced, the pressure loss can be further reduced.
  • the above-mentioned end region refers to both a region into which exhaust gas flows and a region from which exhaust gas flows out.
  • the thickness of the cell partition wall in the end region is preferably 0.1 to 0.5 mm, and the thickness of the cell partition wall in the inner region is 0.12 to 0. It is preferably 4 mm.
  • the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm, the thickness of the cell partition wall is sufficiently reduced without lowering the compressive strength. Therefore, the pressure loss can be further reduced.
  • the thickness of the cell partition wall in the end region is an average value obtained by measuring the width of the cell partition wall at the center of the cell at any 10 points.
  • the shape of the honeycomb structure of the present invention is not limited to a columnar shape, and examples thereof include a prismatic shape, an elliptic cylindrical shape, an oblong cylindrical shape, and a round chamfered prismatic shape (for example, a round chamfered triangular pillar). .
  • the cross-sectional shape of the inner region perpendicular to the longitudinal direction of the cells is not limited to a quadrangle, and may be a triangle, a hexagon, or an octagon, but a quadrangle is preferable.
  • the density of cells in a cross section perpendicular to the longitudinal direction of the honeycomb fired body is preferably 31 to 155 cells / cm 2 (200 to 1000 cells / inch 2 ).
  • the thickness of the outer peripheral coat layer is preferably 0.1 to 2.0 mm.
  • the honeycomb structure of the present invention may be composed of one honeycomb fired body having an outer peripheral wall on the outer periphery, or may be provided with a plurality of honeycomb fired bodies, and the plurality of honeycomb fired bodies are adhesive.
  • the honeycomb fired body has one outer peripheral wall having an outer peripheral wall.
  • the material constituting the honeycomb structure of the present invention is not particularly limited, and examples thereof include carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide, and nitrides such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride.
  • carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide
  • nitrides such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride.
  • examples include ceramics, alumina, zirconia, cordierite, mullite, oxide ceramics such as aluminum titanate, and silicon-containing silicon carbide, but the honeycomb structure is composed of one honeycomb fired body having an outer peripheral wall on the outer periphery. In this case, cordierite or aluminum titanate is preferable.
  • the honeycomb fired body is made of cordierite or aluminum titanate, since the ceramic is a material having a low coefficient of thermal expansion, even when a large thermal stress occurs during regeneration, cracks and the like This is because the honeycomb structure does not easily occur.
  • silica and magnesia also have a role as a firing aid, but as the firing aid, in addition to silica and magnesia, oxides of Y, La, Na, K, Ca, Sr, and Ba are used. It may be used. If necessary, the following additives are added to these mixed powders to obtain a raw material composition.
  • the molding aid include ethylene glycol, dextrin, fatty acid, fatty acid soap, and polyalcohol.
  • the organic binder include hydrophilic organic polymers such as carboxymethyl cellulose, polyvinyl alcohol, methyl cellulose and ethyl cellulose.
  • Examples of the dispersion medium include a dispersion medium composed of only water or a dispersion medium composed of 50% by volume or more of water and an organic solvent.
  • examples of the organic solvent include alcohols such as benzene and methanol.
  • examples of the pore-forming agent include balloons, which are minute hollow spheres, spherical acrylic particles, graphite, and starch.
  • balloons include alumina balloons, glass micro balloons, shirasu balloons, fly ash (FA) balloons, and mullite balloons.
  • the raw material composition may further contain other components.
  • other components include plasticizers, dispersants, and lubricants.
  • plasticizers include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
  • dispersant include sorbitan fatty acid ester.
  • lubricant include glycerin.
  • the molding step is a step of molding the raw material composition obtained in the mixing step to produce an unsealed honeycomb molded body.
  • the unsealed honeycomb molded body can be produced by, for example, extruding the raw material composition using an extrusion die. That is, the unsealed honeycomb molded body is manufactured by extruding the tubular outer peripheral wall of the honeycomb structure and the wall portion constituting the partition wall at one time. Further, in the extrusion molding, a molded body corresponding to the shape of a part of the honeycomb structure may be molded. That is, a honeycomb molded body having the same shape as the honeycomb structure may be manufactured by molding a molded body corresponding to a part of the shape of the honeycomb structure and combining the molded bodies.
  • FIG. 2A is a perspective view schematically showing the unsealed honeycomb molded body produced by the above molding process
  • FIG. 2B is the unsealed honeycomb molded body shown in FIG. 2A
  • FIG. 7 is a sectional view taken along line BB of the body.
  • the cells 22 and 23 have a square cross section perpendicular to the longitudinal direction, and the shape of the cells 22 and 23 at the end faces 20a ′ and 20b ′ is completely zero.
  • An unsealed honeycomb molded body 20 'having the same rectangular shape and having cell partition walls 21 separating cells 22 and 23 and having a cylindrical shape as a whole is produced.
  • a taper jig is used to re-form the unsealed honeycomb molded body 20 ′ to form a portion corresponding to an end region of the honeycomb structure, thereby forming an exhaust gas introduction cell and an exhaust gas discharge cell.
  • the cross-sectional shape of 22 and 23 perpendicular to the longitudinal direction is enlarged or reduced as it approaches the end face, and the sealed honeycomb molded body has a closed shape.
  • the porosity of the end region is higher than that of the inner region after the firing step described later.
  • a honeycomb structure can be manufactured. At this time, water may be applied to the entire end region. Moreover, you may use an organic solvent other than water.
  • FIG. 3 is an explanatory view schematically showing a state of the remolding step of the unsealed honeycomb molded body
  • FIG. 4 is a sectional view schematically showing a state of the remolding step of the unsealed honeycomb molded body. is there.
  • a taper including a support portion 33, a base portion 31 fixed on the support portion 33, and a large number of quadrangular pyramid-shaped tip portions 32 formed on the base portion 31.
  • the corner portion 32c which is the boundary portion of the four flat surfaces 32b forming the quadrangular pyramid of the tip portion 32 forms the square of the cell partition wall 21 on the end surface 20a 'of the unsealed honeycomb molded body 20'.
  • the taper jig 30 is arranged so as to come into contact with the center of the side 21a, and is pushed toward the central portion of the unsealed honeycomb molded body 20 'whose end surface is coated with water.
  • the portion corresponding to the end region of the cell 22 into which the tip 32 is pushed has a shape in which the cross-sectional shape perpendicular to the longitudinal direction of the cell is enlarged as it approaches the end face, and the cell into which the tip 32 is pushed
  • the portions corresponding to the end regions of the cells 23 existing on the upper, lower, left, and right sides of the cell 22 are reduced in shape as the cross-sectional shape perpendicular to the longitudinal direction of the cells 23 approaches the end surface, and become a sealed shape.
  • the shape of the sealed honeycomb formed body viewed from the end face is the same as the honeycomb structure 10 shown in FIG.
  • the square of the cell 12 on the end face 10a is rotated by 45 ° with respect to the square of the cell 12 of the internal region 10B. , Becomes an enlarged shape.
  • the porosity of the cell partition walls in the end region can be adjusted by changing the amount of water applied to the end face or the end region of the unsealed honeycomb molded body.
  • the sealed honeycomb molded body obtained by this remolding step is dried at 100 to 150 ° C. using a dryer such as a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, a vacuum dryer, and a freeze dryer. Then, it is dried in an air atmosphere and degreased at 250 to 400 ° C. and an oxygen concentration of 5% by volume to an air atmosphere.
  • a dryer such as a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, a vacuum dryer, and a freeze dryer.
  • the firing step is a step of firing the sealed honeycomb formed body obtained in the re-forming step at 1400 to 1600 ° C.
  • the reaction with titania proceeds from the surface of alumina to form an aluminum titanate phase.
  • the firing can be performed using a known single furnace, so-called batch furnace, or continuous furnace.
  • the firing temperature is preferably in the range of 1450 to 1550 ° C.
  • the firing time is not particularly limited, but the firing temperature is preferably maintained for 1 to 20 hours, more preferably 1 to 10 hours.
  • the oxygen concentration may be adjusted by mixing an inert gas such as nitrogen gas or argon gas into the air atmosphere.
  • honeycomb structure of the present invention having a high porosity in the end region can be manufactured by undergoing the above-mentioned mixing step, molding step, remolding step, and firing step.
  • Example 1 a raw material composition having the following composition was prepared. Fine titania powder having D50 of 0.6 ⁇ m: 11.1% by weight, coarse titania powder having D50 of 13.0 ⁇ m: 11.1% by weight, alumina powder having D50 of 15.9 ⁇ m: 30.4% by weight, D50 of 1 .1 ⁇ m silica powder: 2.8% by weight, D50 3.8 ⁇ m magnesia powder: 1.4% by weight, D50 31.9 ⁇ m acrylic resin (pore forming material): 18.5% by weight, methylcellulose (organic A binder having a composition of 7.1% by weight, a molding aid (ester type nonion): 4.7% by weight, and ion-exchanged water (dispersion medium): 12.9% by weight are mixed with a mixer. A raw material composition was prepared.
  • the prepared raw material composition was put into an extrusion molding machine and extrusion-molded to prepare an unsealed honeycomb molded body 20 'in which cells were not sealed.
  • the taper jig 30 made of aluminum is used. Remolding was performed to produce the sealed honeycomb molded body of the present invention. As the taper jig 30, the distance (V: valley width shown in FIG.
  • the honeycomb structure was manufactured by holding and firing the sealed honeycomb molded body obtained through the remolding step at 1450 ° C. for 15 hours in the air atmosphere.
  • the obtained honeycomb structure had a size of 34 mm ⁇ 34 mm ⁇ 100 mm, a peripheral wall thickness of 0.3 mm, a cell partition wall thickness of 0.19 mm in the end region, and a cell partition wall thickness of 0.25 mm in the inner region.
  • the number of cells (cell density) was 300 cells / inch 2 , and it was a quadrangular prism shape.
  • the porosity was measured by the method described below.
  • Example 1 A honeycomb structure was manufactured in the same manner as in Example 1 except that water was not applied to both end surfaces of the unsealed honeycomb molded body 20 'during the remolding.
  • Example 1 and Comparative Example 1 the porosity and pressure loss of the obtained honeycomb structure were measured.
  • FIG. 5 is sectional drawing which shows the pressure loss measuring method typically.
  • the honeycomb structure 10 obtained in Example 1 is fixedly arranged in the metal casing 213 in the pipe 212 of the blower 211, and the pressure before and after the honeycomb structure 10 can be detected.
  • a pressure gauge 214 is attached so that The end of the honeycomb structure 10 on the exhaust gas inlet side is arranged on the side close to the pipe 212 of the blower 211. That is, the gas is arranged so as to flow into a cell having an open end on the exhaust gas inlet side.
  • the pressure loss when the gas of 300 L / min was passed through the honeycomb structure 10 from the blower 211 was defined as the pressure loss (kPa) of this honeycomb structure.
  • the average value of pressure loss obtained in Example 1 was 2.4 kPa, and the average value of pressure loss obtained in Comparative Example 1 was 2.8 kPa.

Abstract

This honeycomb structure is provided with: a porous cell partition wall that delimits and forms a plurality of cells serving as exhaust gas flow paths; exhaust gas introduction cells in which the end surface on an exhaust gas inlet side is open and the end surface on an exhaust gas outlet side is sealed; and exhaust gas discharge cells in which the end surface on the exhaust gas outlet side is open and the end surface on the exhaust gas inlet side is sealed. The honeycomb structure is characterized in that the exhaust gas introduction cells and the exhaust gas discharge cells comprise internal regions in which the shape of a cross section perpendicular to the lengthwise direction of the exhaust gas introduction cells and the exhaust gas discharge cells is uniform and end regions in which the shape of a cross section perpendicular to the lengthwise direction of the exhaust gas introduction cells and the exhaust gas discharge cells increases or decreases in size as proximity to the end surfaces increases. The honeycomb structure is also characterized in that the porosity in the end regions is higher than the porosity in the internal regions.

Description

ハニカム構造体Honeycomb structure
本発明は、ハニカム構造体に関する。 The present invention relates to a honeycomb structure.
ガソリンエンジンやディーゼルエンジン等の内燃機関から排出される排ガス中には、スス等のパティキュレート（以下、ＰＭともいう）が含まれており、近年、このＰＭが環境または人体に害を及ぼすことが問題となっている。また、排ガス中には、ＣＯ、ＨＣまたはＮＯｘ等の有害なガス成分も含まれていることから、この有害なガス成分が環境または人体に及ぼす影響についても懸念されている。 The exhaust gas discharged from an internal combustion engine such as a gasoline engine or a diesel engine contains particulates such as soot (hereinafter, also referred to as PM), and in recent years, this PM may be harmful to the environment or the human body. It's a problem. Moreover, since harmful gas components such as CO, HC or NOx are also contained in the exhaust gas, there is concern about the effect of these harmful gas components on the environment or the human body.
そこで、内燃機関と連結されることにより排ガス中のＰＭを捕集したり、排ガスに含まれるＣＯ、ＨＣまたはＮＯｘ等の排ガス中の有害なガス成分を浄化したりする排ガス浄化装置として、チタン酸アルミニウム、コージェライト、炭化ケイ素等の多孔質セラミックからなるハニカム構造体が種々提案されている。 Therefore, titanic acid is used as an exhaust gas purifying apparatus for collecting PM in exhaust gas by connecting with an internal combustion engine and purifying harmful gas components such as CO, HC or NOx contained in the exhaust gas. Various honeycomb structures made of porous ceramics such as aluminum, cordierite, and silicon carbide have been proposed.
また、これらのハニカムフィルタでは、内燃機関の燃費を改善し、圧力損失の上昇に起因する運転時のトラブル等をなくすために、圧力損失の低いハニカム構造体からなるフィルタが種々提案されている。 Further, in these honeycomb filters, in order to improve fuel efficiency of an internal combustion engine and eliminate troubles during operation due to an increase in pressure loss, various filters having a honeycomb structure with low pressure loss have been proposed.
特許文献１には、一端面で開放されて他端面で閉じられた複数の第１流路、及び、前記一端面で閉じられて前記他端面で開放された複数の第２流路を有し、各前記第１流路及び各前記第２流路の断面積がそれぞれ軸方向に一定である中央隔壁と、前記中央隔壁から前記他端面に向かって、各前記第１流路の断面積が縮小され、かつ、各前記第２流路の断面積が拡大される、他端側傾斜隔壁と、を備えるハニカム構造体であって、前記他端側傾斜隔壁の軸方向長さは４ｍｍ以上であるハニカム構造体が開示されている。 Patent Document 1 has a plurality of first flow paths that are open at one end surface and closed at the other end surface, and a plurality of second flow paths that are closed at the one end surface and open at the other end surface. A central partition wall in which the cross-sectional area of each of the first flow paths and the second flow path is constant in the axial direction, and a cross-sectional area of each of the first flow paths from the central partition wall toward the other end surface. A honeycomb structure including: the other end side inclined partition wall, which is reduced and has a larger cross-sectional area of each of the second flow paths, wherein the other end side inclined partition wall has an axial length of 4 mm or more. A honeycomb structure is disclosed.
特許文献１の段落番号［００２１］には、ハニカム構造体の隔壁の空隙率は、４０～７０％とすることができると記載されており、他に気孔率に関する記載はないため、特許文献１に記載されたハニカム構造体においては、隔壁の気孔率は、特定の部分で変化させることなく、全体的に同じ気孔率としていたと考えられる。 Paragraph No. [0021] of Patent Document 1 describes that the porosity of the partition walls of the honeycomb structure can be 40 to 70%, and there is no other description regarding the porosity, and therefore Patent Document 1 In the honeycomb structure described in (1), it is considered that the partition walls had the same porosity as a whole without changing the porosity at a specific portion.
しかしながら、隔壁が上記のような全体的に同じ気孔率では、傾斜隔壁をＰＭの捕集面積として充分に使えておらず、より圧力損失の低いハニカム構造体が求められている。ハニカム構造体の圧力損失を低減させるためにガス透過性を向上させる方法としては、材料配合や焼成条件を変えて全体の気孔率を上げる方法が考えられる。 However, when the partition walls have the same overall porosity as described above, the inclined partition walls cannot be used sufficiently as a PM trapping area, and a honeycomb structure having a lower pressure loss is required. As a method for improving the gas permeability in order to reduce the pressure loss of the honeycomb structure, a method of increasing the overall porosity by changing the material composition and firing conditions can be considered.
再公表２０１６－０９８８３５号Republished 2016-098835
しかしながら、ハニカム構造体全体の気孔率を上げると、機械的強度が低下し、フィルタとしての使用時に破損が発生するおそれがあった。 However, if the porosity of the whole honeycomb structure is increased, the mechanical strength is lowered, and there is a possibility that breakage may occur during use as a filter.
本発明は、このような問題に鑑みてなされたものであり、機械的特性を劣化させることなく、圧力損失の低いハニカム構造体を提供することを目的とする。 The present invention has been made in view of such a problem, and an object thereof is to provide a honeycomb structure having a low pressure loss without deteriorating the mechanical characteristics.
本発明のハニカム構造体は、排ガスの流路となる複数のセルを区画形成する多孔質のセル隔壁と、排ガス入口側の端面が開口され且つ排ガス出口側の端面が封じられている排ガス導入セルと、排ガス出口側の端面が開口され且つ排ガス入口側の端面が封じられている排ガス排出セルとを備えたハニカム構造体であって、
上記排ガス導入セル及び上記排ガス排出セルは、上記排ガス導入セル及び上記排ガス排出セルの長手方向に垂直な断面形状が一定である内部領域と、上記排ガス導入セル及び上記排ガス排出セルの長手方向に垂直な断面形状が端面に近づくに従って拡大又は縮小されている端部領域とからなり、
上記端部領域における気孔率は、上記内部領域における気孔率よりも高いことを特徴とする。 The honeycomb structure of the present invention is a porous cell partition wall that partitions and forms a plurality of cells that are channels of exhaust gas, and an exhaust gas introduction cell in which the end surface on the exhaust gas inlet side is opened and the end surface on the exhaust gas outlet side is closed. And a honeycomb structure including an exhaust gas discharge cell in which an end surface on the exhaust gas outlet side is opened and an end surface on the exhaust gas inlet side is sealed,
The exhaust gas introduction cell and the exhaust gas discharge cell, the exhaust gas introduction cell and an internal region having a constant cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas discharge cell, and vertical to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell A cross-sectional shape that is enlarged or reduced as it approaches the end surface,
The porosity in the end region is higher than the porosity in the inner region.
なお、上記排ガス導入セルの排ガス出口側の端面及び上記排ガス排出セルの排ガス入口側の端面が封じられているとは、上記した端面を含む部分が封止剤を充填することにより目封じされているのではなく、上記端部領域において、セルの長手方向に垂直な断面形状が端面に近づくに従って縮小され、端面において上記断面の面積が０となり、閉じられていることをいう。 The end face of the exhaust gas introduction cell on the exhaust gas outlet side and the end face of the exhaust gas discharge cell on the exhaust gas inlet side are sealed by filling a part including the end face with a sealant. Rather than being present, it means that the cross-sectional shape perpendicular to the longitudinal direction of the cell is reduced as it approaches the end face in the end region, the area of the cross section becomes 0 at the end face, and the cell is closed.
本発明のハニカム構造体における排ガス導入セルの端部領域及び排ガス排出セルの端部領域では、上記排ガス導入セル及び上記排ガス排出セルの長手方向に垂直な断面形状が端面に近づくに従って拡大又は縮小されており、上記端部領域における気孔率は、上記内部領域における気孔率よりも高いので、機械的強度を維持しつつ、端部領域におけるセル隔壁を排ガスが透過し易くなり、端部領域もＰＭの捕集面積として使えるため、排ガスのセル隔壁透過及びセル隔壁に堆積したＰＭ層の透過に起因する圧力損失を低減させることができる。 In the end region of the exhaust gas introduction cell and the end region of the exhaust gas discharge cell in the honeycomb structure of the present invention, the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell is enlarged or reduced as it approaches the end face. Since the porosity in the end region is higher than the porosity in the inner region, the exhaust gas easily permeates the cell partition walls in the end region while maintaining the mechanical strength, and the end region is also PM. Since it can be used as a trapping area for exhaust gas, it is possible to reduce the pressure loss due to the permeation of exhaust gas into cell partition walls and the permeation of the PM layer deposited on the cell partition walls.
また、本発明のハニカム構造体では、排ガス入口側及び出口側の端面で開口率が高くなっているので、排ガスがハニカム構造体に流入する際及び排ガス構造体から流出する際の抵抗が小さくなり、圧力損失をさらに低減させることができる。 Further, in the honeycomb structure of the present invention, since the opening ratio is high at the end faces of the exhaust gas inlet side and the outlet side, the resistance when the exhaust gas flows into the honeycomb structure and flows out from the exhaust gas structure becomes small. The pressure loss can be further reduced.
本発明のハニカム構造体では、上記端部領域における気孔率は、上記内部領域における気孔率よりも０．５～５％高いことが望ましい。
本発明のハニカム構造体において、上記端部領域における気孔率が、上記内部領域における気孔率よりも０．５～５％高いと、排ガスの入り口と出口の排ガスの透過性をより向上させることができ、機械的強度を維持しつつ、排ガスのセル隔壁透過及びセル隔壁に堆積したＰＭ層の透過に起因する圧力損失を充分に低減させることができる。 In the honeycomb structure of the present invention, it is desirable that the porosity in the end area is 0.5 to 5% higher than the porosity in the inner area.
In the honeycomb structure of the present invention, when the porosity in the end area is 0.5 to 5% higher than the porosity in the inner area, the exhaust gas permeability at the exhaust gas inlet and outlet can be further improved. Therefore, it is possible to sufficiently reduce the pressure loss due to the permeation of the exhaust gas into the cell partition walls and the permeation of the PM layer deposited on the cell partition walls while maintaining the mechanical strength.
本発明のハニカム構造体において、上記端部領域における気孔率の高さが、上記内部領域における気孔率に対し０．５％未満であると、排ガスの入り口と出口の排ガスのセル隔壁透過性を充分に向上させることが難しくなり、一方、上記端部領域における気孔率の高さが、上記内部領域における気孔率に対し５％を超えると、端部領域の機械的強度が低下し、端部領域が破損し易くなる。 In the honeycomb structure of the present invention, when the high porosity in the end area is less than 0.5% with respect to the porosity in the inner area, the cell partition wall permeability of the exhaust gas at the inlet and the outlet is improved. If it is difficult to sufficiently improve the porosity in the end region above 5% with respect to the porosity in the inner region, the mechanical strength of the end region is reduced and The area is easily damaged.
本発明のハニカム構造体では、上記内部領域におけるセル隔壁の気孔率は、３５～６５％であることが望ましい。
本発明のハニカム構造体において、上記内部領域におけるセル隔壁の気孔率が、３５～６５％であると、内部領域に起因する圧力損失の上昇を抑制することができ、かつ、充分な機械的強度を維持することができる。 In the honeycomb structure of the present invention, the porosity of the cell partition walls in the inner region is preferably 35 to 65%.
In the honeycomb structure of the present invention, when the porosity of the cell partition walls in the internal region is 35 to 65%, it is possible to suppress an increase in pressure loss due to the internal region and to obtain sufficient mechanical strength. Can be maintained.
セル隔壁の気孔率が３５％未満では、内部領域におけるセル隔壁の気孔の割合が小さすぎるため、排ガスが内部領域におけるセル隔壁を透過しにくくなり、圧力損失が大きくなる。一方、セル隔壁の気孔率が６５％を超えると、内部領域におけるセル隔壁の機械的特性が充分でなく、再生時等において、クラックが発生し易くなる。 When the porosity of the cell partition walls is less than 35%, the proportion of the pores of the cell partition walls in the inner region is too small, so that the exhaust gas is less likely to pass through the cell partition walls in the inner region and the pressure loss increases. On the other hand, when the porosity of the cell partition walls exceeds 65%, the mechanical properties of the cell partition walls in the internal region are not sufficient, and cracks are likely to occur during reproduction or the like.
本発明のハニカム構造体では、上記端部領域における気孔の平均気孔径は、５～３０μｍであることが望ましい。 In the honeycomb structure of the present invention, it is desirable that the average pore diameter of the pores in the end region is 5 to 30 μm.
本発明のハニカム構造体において、上記セル隔壁に含まれる気孔の平均気孔径が、５～３０μｍであると、圧力損失を低く保ちながら、高い捕集効率でＰＭを捕集することができる。 In the honeycomb structure of the present invention, when the average pore diameter of the pores contained in the cell partition walls is 5 to 30 μm, PM can be collected with high collection efficiency while keeping the pressure loss low.
セル隔壁に含まれる気孔の平均気孔径が５μｍ未満であると、気孔が小さすぎるため、排ガスがセル隔壁を透過する際の圧力損失が大きくなる。一方、セル隔壁に含まれる気孔の平均気孔径が３０μｍを超えると、気孔径が大きくなりすぎるので、ＰＭの捕集効率が低下してしまう。 If the average pore diameter of the pores contained in the cell partition walls is less than 5 μm, the pores are too small, and the pressure loss when exhaust gas permeates the cell partition walls increases. On the other hand, if the average pore diameter of the pores contained in the cell partition wall exceeds 30 μm, the pore diameter becomes too large, and the PM trapping efficiency decreases.
本発明のハニカム構造体では、上記端部領域のセルの長手方向の長さは、１～１０ｍｍであることが望ましい。
本発明のハニカム構造体において、上記端部領域のセルの長手方向の長さが、１～１０ｍｍであると、排ガス入口側において、排ガスがセル内部に導入される抵抗、及び、排ガス出口側において、排ガスがセル内部より排出される抵抗をより小さくできるため、圧力損失をさらに低減させることができる。 In the honeycomb structure of the present invention, the length of the cells in the end region in the longitudinal direction is preferably 1 to 10 mm.
In the honeycomb structure of the present invention, when the length in the longitudinal direction of the cells in the end region is 1 to 10 mm, the resistance at which the exhaust gas is introduced into the cells at the exhaust gas inlet side and the exhaust gas outlet side at the exhaust gas outlet side Since the resistance of the exhaust gas discharged from the inside of the cell can be further reduced, the pressure loss can be further reduced.
本発明のハニカム構造体において、上記端部領域のセルの長手方向の長さが、１ｍｍ未満であると、排ガス入口側において、セル内部への排ガスを導入する際の抵抗が大きくなり、排ガス出口側において、排ガスが排出される際の抵抗が大きくなるため、圧力損失を充分に低減できなくなり、一方、上記端部領域のセルの長手方向の長さが、１０ｍｍを超えると、そのような構造のハニカム構造体の製造が難しくなる。 In the honeycomb structure of the present invention, when the length of the cells in the end region in the longitudinal direction is less than 1 mm, the resistance at the time of introducing the exhaust gas into the cells on the exhaust gas inlet side increases, and the exhaust gas outlet On the side, since the resistance when exhaust gas is discharged becomes large, it is not possible to sufficiently reduce the pressure loss. On the other hand, when the length of the cell in the end region in the longitudinal direction exceeds 10 mm, such a structure is formed. It becomes difficult to manufacture the honeycomb structure.
本発明のハニカム構造体では、上記端部領域におけるセル隔壁の厚さは、０．１～０．５ｍｍであることが望ましい。
本発明のハニカム構造体において、上記端部領域におけるセル隔壁の厚さが、０．１～０．５ｍｍであると、圧縮強度を低下させることなく、セル隔壁の厚さを充分に薄くすることができるので、圧力損失をさらに低減させることができる。 In the honeycomb structure of the present invention, it is desirable that the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm.
In the honeycomb structure of the present invention, when the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm, the thickness of the cell partition wall is sufficiently reduced without lowering the compressive strength. Therefore, the pressure loss can be further reduced.
本発明のハニカム構造体において、上記端部領域におけるセル隔壁の厚さが、０．１ｍｍ未満であると、セル隔壁の厚さが薄すぎることとなり、圧縮強度を低下させてしまう。一方、セル隔壁の厚さが０．５ｍｍを超えると、セル隔壁の厚さが厚すぎるため、圧力損失を充分に低減させることが難しくなる。 In the honeycomb structure of the present invention, if the thickness of the cell partition wall in the end region is less than 0.1 mm, the thickness of the cell partition wall becomes too thin, which lowers the compressive strength. On the other hand, when the thickness of the cell partition wall exceeds 0.5 mm, the thickness of the cell partition wall is too thick, and it becomes difficult to sufficiently reduce the pressure loss.
本発明のハニカム構造体において、上記内部領域におけるセルの長手方向に垂直な断面形状は、四角形であることが望ましい。
本発明のハニカム構造体において、上記内部領域におけるセルの長手方向に垂直な断面形状が、四角形であると、ハニカム構造体を製造する際、上記端部領域において、セルの長手方向に垂直な断面形状を、端面に近づくに従って拡大又は縮小させ易く、圧力損失が充分に低いハニカム構造体の実現が可能となる。 In the honeycomb structure of the present invention, it is desirable that the cross-sectional shape of the cells in the inner region, which is perpendicular to the longitudinal direction, be quadrangular.
In the honeycomb structure of the present invention, the cross-sectional shape perpendicular to the longitudinal direction of the cells in the internal region is a quadrangle, and in manufacturing the honeycomb structure, in the end region, a cross-section perpendicular to the longitudinal direction of the cells. The shape can be easily expanded or reduced as it approaches the end face, and a honeycomb structure having a sufficiently low pressure loss can be realized.
本発明のハニカム構造体では、上記ハニカム構造体は、外周に外周壁を有する一のハニカム焼成体により構成されていることが望ましい。
本発明のハニカム構造体においては、接着剤を用いて多数のハニカムセグメントを組み合わせたハニカム構造体に比べて、接着層がない分、端面における開口率を高くできるため、圧力損失の低減効果がより発揮できる。 In the honeycomb structure of the present invention, it is desirable that the honeycomb structure is made of one honeycomb fired body having an outer peripheral wall on the outer periphery.
In the honeycomb structure of the present invention, as compared with the honeycomb structure in which a large number of honeycomb segments are combined by using an adhesive, the opening ratio at the end face can be increased due to the absence of the adhesive layer, so that the pressure loss reducing effect is further improved. Can be demonstrated.
本発明のハニカム構造体では、上記ハニカム焼成体は、コージェライト、又は、チタン酸アルミニウムからなることが望ましい。
本発明のハニカム構造体において、上記ハニカム焼成体が、コージェライト、又は、チタン酸アルミニウムからなると、上記セラミックは、熱膨張率の低い材料であるので、再生時等において大きな熱応力が発生した場合であっても、クラック等の発生しにくいハニカム構造体となる。 In the honeycomb structure of the present invention, the honeycomb fired body is preferably made of cordierite or aluminum titanate.
In the honeycomb structure of the present invention, when the honeycomb fired body is made of cordierite or aluminum titanate, since the ceramic is a material having a low coefficient of thermal expansion, when large thermal stress occurs during regeneration or the like. Even in this case, the honeycomb structure is resistant to cracks.
図１（ａ）は、本発明のハニカム構造体の一例を模式的に示す斜視図であり、図１（ｂ）は、図１（ａ）におけるＡ－Ａ線断面図であり、図１（ｃ）は、一方の端面側から見た端面図である。1 (a) is a perspective view schematically showing an example of the honeycomb structure of the present invention, and FIG. 1 (b) is a sectional view taken along the line AA in FIG. 1 (a). c) is an end view as seen from one end surface side. 図２（ａ）は、未封止ハニカム成形体を模式的に示す斜視図であり、図２（ｂ）は、図２（ａ）に示した未封止ハニカム成形体のＢ－Ｂ線断面図である。FIG. 2 (a) is a perspective view schematically showing an unsealed honeycomb molded body, and FIG. 2 (b) is a cross section taken along line BB of the unsealed honeycomb molded body shown in FIG. 2 (a). It is a figure. 図３は、未封止ハニカム成形体の再成形工程の様子を模式的に示す説明図である。FIG. 3 is an explanatory view schematically showing a state of a remolding step of the unsealed honeycomb molded body. 図４は、未封止ハニカム成形体の再成形工程の様子を模式的に示す断面図である。FIG. 4 is a cross-sectional view schematically showing a state of a remolding step of the unsealed honeycomb molded body. 図５は、圧力損失測定方法を模式的に示す断面図である。FIG. 5: is sectional drawing which shows the pressure loss measuring method typically.
（発明の詳細な説明）
［ハニカム構造体］
まず、本発明のハニカム構造体について説明する。 (Detailed description of the invention)
[Honeycomb structure]
First, the honeycomb structure of the present invention will be described.
本発明のハニカム構造体は、排ガスの流路となる複数のセルを区画形成する多孔質のセル隔壁と、排ガス入口側の端面が開口され且つ排ガス出口側の端面が封じられている排ガス導入セルと、排ガス出口側の端面が開口され且つ排ガス入口側の端面が封じられている排ガス排出セルとを備えたハニカム構造体であって、上記排ガス導入セル及び上記排ガス排出セルは、上記排ガス導入セル及び上記排ガス排出セルの長手方向に垂直な断面形状が一定である内部領域と、上記排ガス導入セル及び上記排ガス排出セルの長手方向に垂直な断面形状が端面に近づくに従って拡大又は縮小されている端部領域とからなり、前記端部領域における気孔率は、前記内部領域における気孔率よりも高いことを特徴とする。 The honeycomb structure of the present invention is a porous cell partition wall that partitions and forms a plurality of cells that are channels of exhaust gas, and an exhaust gas introduction cell in which an end surface on the exhaust gas inlet side is opened and an end surface on the exhaust gas outlet side is closed. And a honeycomb structure having an exhaust gas discharge cell in which an end face on the exhaust gas outlet side is opened and an end face on the exhaust gas inlet side is sealed, wherein the exhaust gas introducing cell and the exhaust gas discharging cell are the exhaust gas introducing cells And an inner region in which the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas discharge cell is constant, and an end where the cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell is enlarged or reduced as it approaches the end surface. And a porosity in the end region is higher than a porosity in the inner region.
図１（ａ）は、本発明のハニカム構造体の一例を模式的に示す斜視図であり、図１（ｂ）は、図１（ａ）におけるＡ－Ａ線断面図であり、図１（ｃ）は、一方の端面側から見た端面図である。
図１（ａ）及び図１（ｂ）に示すハニカム構造体１０は、排ガスの流路となる複数のセル１２、１３を区画形成する多孔質のセル隔壁１１と、排ガス入口側の端面１０ａが開口され且つ排ガス出口側の端面１０ｂが封じられている排ガス導入セル１２と、排ガス出口側の端面１０ｂが開口され且つ排ガス入口側の端面１０ａが封じられている排ガス排出セル１３とを備え、排ガス導入セル１２及び排ガス排出セル１３は、排ガス導入セル１２及び排ガス排出セル１３の長手方向に垂直な断面形状が一定である内部領域１０Ｂと、排ガス導入セル１２及び排ガス排出セル１３の長手方向に垂直な断面形状が端面に近づくに従って拡大され、又は、縮小され、封じられている端部領域１０Ａ、１０Ｃとからなる。
図１（ａ）及び図１（ｂ）に示すように、ハニカム構造体１０が単一のハニカム焼成体からなる場合、ハニカム焼成体はハニカム構造体でもある。 1 (a) is a perspective view schematically showing an example of the honeycomb structure of the present invention, and FIG. 1 (b) is a sectional view taken along the line AA in FIG. 1 (a). c) is an end view as seen from one end surface side.
The honeycomb structure 10 shown in FIGS. 1 (a) and 1 (b) has a porous cell partition wall 11 for partitioning and forming a plurality of cells 12 and 13 serving as exhaust gas flow paths, and an end face 10a on the exhaust gas inlet side. An exhaust gas introduction cell 12 that is opened and has an end face 10b on the exhaust gas outlet side sealed, and an exhaust gas discharge cell 13 that has an end face 10b on the exhaust gas outlet side opened and the end face 10a on the exhaust gas inlet side are sealed, The introduction cell 12 and the exhaust gas discharge cell 13 are perpendicular to the longitudinal direction of the exhaust gas introduction cell 12 and the exhaust gas discharge cell 13 and the internal region 10B having a constant sectional shape perpendicular to the longitudinal direction of the exhaust gas introduction cell 12 and the exhaust gas discharge cell 13. The cross-sectional shape is enlarged or reduced as it approaches the end face, and the end regions 10A and 10C are sealed.
As shown in FIGS. 1A and 1B, when the honeycomb structure 10 is made of a single honeycomb fired body, the honeycomb fired body is also a honeycomb structure.
本発明のハニカム構造体１０では、端部領域１０Ａ、１０Ｃにおける気孔率は、内部領域１０Ｂにおける気孔率よりも高い。
このため、排ガスの入り口と出口の排ガスの透過性を向上させることができ、機械的強度を維持しつつ、排ガスのセル隔壁透過及びセル隔壁に堆積したＰＭ層透過に起因する圧力損失を低減させることができる。 In the honeycomb structure 10 of the present invention, the porosity in the end regions 10A and 10C is higher than that in the inner region 10B.
Therefore, it is possible to improve the permeability of the exhaust gas at the inlet and the outlet of the exhaust gas, and reduce the pressure loss due to the permeation of the exhaust gas into the cell partition walls and the permeation of the PM layer deposited on the cell partition walls while maintaining the mechanical strength. be able to.
本発明のハニカム構造体では、上記端部領域における気孔率は、上記内部領域における気孔率よりも０．５～５％高いことが望ましい。
本発明のハニカム構造体において、上記端部領域における気孔率が、上記内部領域における気孔率よりも０．５～５％高いと、排ガスのセル隔壁透過性をより向上させることができ、機械的強度を保ちつつ、排ガスのセル隔壁透過及び堆積したＰＭ層透過による圧力損失を充分に低減させることができる。 In the honeycomb structure of the present invention, it is desirable that the porosity in the end area is 0.5 to 5% higher than the porosity in the inner area.
In the honeycomb structure of the present invention, when the porosity in the end region is higher than the porosity in the inner region by 0.5 to 5%, the cell partition wall permeability of the exhaust gas can be further improved, and the mechanical strength can be improved. It is possible to sufficiently reduce the pressure loss due to the permeation of exhaust gas through the cell partition walls and the permeation of the deposited PM layer while maintaining the strength.
本発明のハニカム構造体では、上記内部領域におけるセル隔壁の気孔率は、３５～６５％であることが望ましい。
本発明のハニカム構造体において、上記内部領域におけるセル隔壁の気孔率が、３５～６５％であると、内部領域に起因する圧力損失の上昇を抑制することができ、かつ、充分な機械的強度を維持することができる。
本発明のハニカム構造体では、内部領域におけるセル隔壁の気孔率は、３５～６５％であるので、端部領域における気孔率は、３５．５～７０％となる。このように、端部領域における気孔率は、内部領域に比べて高くなるが、気孔率の高い領域は限定されており、内部領域から続いているので、機械的強度の劣化は抑制され、かつ、圧力損失を低減させることができる。 In the honeycomb structure of the present invention, the porosity of the cell partition walls in the inner region is preferably 35 to 65%.
In the honeycomb structure of the present invention, when the porosity of the cell partition walls in the internal region is 35 to 65%, it is possible to suppress an increase in pressure loss due to the internal region and to obtain sufficient mechanical strength. Can be maintained.
In the honeycomb structure of the present invention, the porosity of the cell partition walls in the inner region is 35 to 65%, so that the porosity in the end region is 35.5 to 70%. Thus, the porosity in the end region is higher than in the inner region, but the region of high porosity is limited and continues from the inner region, so deterioration of mechanical strength is suppressed, and The pressure loss can be reduced.
本発明のハニカム構造体では、上記端部領域における気孔の平均気孔径は、５～３０μｍであることが望ましい。
本発明のハニカム構造体において、上記端部領域のセル隔壁に含まれる気孔の平均気孔径が、５～３０μｍであると、圧力損失を低く保ちながら、高い捕集効率でＰＭを捕集することができる。
本発明のハニカム構造体において、気孔率および平均気孔径は、水銀圧入法にて接触角を１３０°、表面張力を４８５ｍＮ／ｍの条件で測定する。 In the honeycomb structure of the present invention, it is desirable that the average pore diameter of the pores in the end region is 5 to 30 μm.
In the honeycomb structure of the present invention, when the average pore diameter of the pores contained in the cell partition walls in the end region is 5 to 30 μm, PM can be trapped with high trapping efficiency while keeping the pressure loss low. You can
In the honeycomb structure of the present invention, the porosity and the average pore diameter are measured by a mercury intrusion method under the conditions of a contact angle of 130 ° and a surface tension of 485 mN / m.
本発明のハニカム構造体において、上記端部領域のセルの長手方向の長さは、１～１０ｍｍであることが望ましい。
本発明のハニカム構造体において、上記端部領域のセルの長手方向の長さが、１～１０ｍｍであると、排ガス入口側において、排ガスがセル内部に導入される抵抗、及び、排ガス出口側において、排ガスがセル内部より排出される抵抗をより小さくすることができるため、圧力損失をさらに低減させることができる。なお、上記した端部領域は、排ガスが流入する領域と排ガスが流出する領域の両方をいうものとする。 In the honeycomb structure of the present invention, it is desirable that the length of the cells in the end region is 1 to 10 mm in the longitudinal direction.
In the honeycomb structure of the present invention, when the length in the longitudinal direction of the cells in the end region is 1 to 10 mm, the resistance at which the exhaust gas is introduced into the cells at the exhaust gas inlet side and the exhaust gas outlet side at the exhaust gas outlet side Since the resistance of the exhaust gas discharged from the inside of the cell can be further reduced, the pressure loss can be further reduced. In addition, the above-mentioned end region refers to both a region into which exhaust gas flows and a region from which exhaust gas flows out.
本発明のハニカム構造体において、上記端部領域におけるセル隔壁の厚さは、０．１～０．５ｍｍであることが望ましく、上記内部領域におけるセル隔壁の厚さは、０．１２～０．４ｍｍであることが望ましい。
本発明のハニカム構造体において、上記端部領域におけるセル隔壁の厚さが、０．１～０．５ｍｍであると、圧縮強度を低下させることなく、セル隔壁の厚さを充分に薄くすることができるので、圧力損失をさらに低減させることができる。なお、端部領域におけるセル隔壁の厚さは、セルの中心部におけるセル隔壁の幅を任意の１０点測定し、その平均値とする。 In the honeycomb structure of the present invention, the thickness of the cell partition wall in the end region is preferably 0.1 to 0.5 mm, and the thickness of the cell partition wall in the inner region is 0.12 to 0. It is preferably 4 mm.
In the honeycomb structure of the present invention, when the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm, the thickness of the cell partition wall is sufficiently reduced without lowering the compressive strength. Therefore, the pressure loss can be further reduced. The thickness of the cell partition wall in the end region is an average value obtained by measuring the width of the cell partition wall at the center of the cell at any 10 points.
本発明のハニカム構造体の形状としては、円柱状に限定されず、角柱状、楕円柱状、長円柱状、丸面取りされている角柱状（例えば、丸面取りされている三角柱状）等が挙げられる。 The shape of the honeycomb structure of the present invention is not limited to a columnar shape, and examples thereof include a prismatic shape, an elliptic cylindrical shape, an oblong cylindrical shape, and a round chamfered prismatic shape (for example, a round chamfered triangular pillar). .
本発明のハニカム構造体において、内部領域におけるセルの長手方向に垂直な断面形状は、四角形に限定されず、三角形、六角形、八角形であってもよいが、四角形であることが望ましい。 In the honeycomb structure of the present invention, the cross-sectional shape of the inner region perpendicular to the longitudinal direction of the cells is not limited to a quadrangle, and may be a triangle, a hexagon, or an octagon, but a quadrangle is preferable.
本発明のハニカム構造体において、ハニカム焼成体の長手方向に垂直な断面のセルの密度は、３１～１５５個／ｃｍ２（２００～１０００個／ｉｎｃｈ２）であることが望ましい。 In the honeycomb structure of the present invention, the density of cells in a cross section perpendicular to the longitudinal direction of the honeycomb fired body is preferably 31 to 155 cells / cm 2 (200 to 1000 cells / inch 2 ).
本発明のハニカム構造体において、ハニカム焼成体の外周面に外周コート層が形成されている場合、外周コート層の厚さは、０．１～２．０ｍｍであることが望ましい。 In the honeycomb structure of the present invention, when the outer peripheral coat layer is formed on the outer peripheral surface of the honeycomb fired body, the thickness of the outer peripheral coat layer is preferably 0.1 to 2.0 mm.
本発明のハニカム構造体は、外周に外周壁を有する一のハニカム焼成体により構成されていてもよいし、複数個のハニカム焼成体を備えていてもよく、複数個のハニカム焼成体が接着剤により結合されていてもよいが、外周に外周壁を有する一のハニカム焼成体により構成されていることが望ましい。 The honeycomb structure of the present invention may be composed of one honeycomb fired body having an outer peripheral wall on the outer periphery, or may be provided with a plurality of honeycomb fired bodies, and the plurality of honeycomb fired bodies are adhesive. However, it is preferable that the honeycomb fired body has one outer peripheral wall having an outer peripheral wall.
本発明のハニカム構造体を構成する材料は、特に限定されず、例えば、炭化ケイ素、炭化チタン、炭化タンタル、炭化タングステン等の炭化物セラミック、窒化アルミニウム、窒化ケイ素、窒化ホウ素、窒化チタン等の窒化物セラミック、アルミナ、ジルコニア、コージェライト、ムライト、チタン酸アルミニウム等の酸化物セラミック、ケイ素含有炭化ケイ素等が挙げられるが、ハニカム構造体が外周に外周壁を有する一のハニカム焼成体により構成されている場合には、コージェライト、又は、チタン酸アルミニウムが好ましい。 The material constituting the honeycomb structure of the present invention is not particularly limited, and examples thereof include carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide, and nitrides such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Examples include ceramics, alumina, zirconia, cordierite, mullite, oxide ceramics such as aluminum titanate, and silicon-containing silicon carbide, but the honeycomb structure is composed of one honeycomb fired body having an outer peripheral wall on the outer periphery. In this case, cordierite or aluminum titanate is preferable.
上記ハニカム焼成体が、コージェライト、又は、チタン酸アルミニウムからなると、上記セラミックは、熱膨張率の低い材料であるので、再生時等において大きな熱応力が発生した場合であっても、クラック等の発生しにくいハニカム構造体となるからである。 When the honeycomb fired body is made of cordierite or aluminum titanate, since the ceramic is a material having a low coefficient of thermal expansion, even when a large thermal stress occurs during regeneration, cracks and the like This is because the honeycomb structure does not easily occur.
次に、本発明のハニカム構造体の製造方法について説明する。
以下においては、チタン酸アルミニウムからなるハニカム構造体の製造方法を例にとって説明するが、本発明の製造対象は、チタン酸アルミニウムに限定されるものではない。
（混合工程）
まず、アルミナ粉末及びチタニア粉末にマグネシア粉末、シリカ粉末等の添加剤を添加し、混合することにより混合粉末を得る。 Next, a method for manufacturing the honeycomb structure of the present invention will be described.
In the following, a method for manufacturing a honeycomb structure made of aluminum titanate will be described as an example, but the manufacturing target of the present invention is not limited to aluminum titanate.
(Mixing process)
First, additives such as magnesia powder and silica powder are added to alumina powder and titania powder and mixed to obtain a mixed powder.
上記混合粉末において、シリカとマグネシアは、焼成助剤としての役割もあるが、焼成助剤としては、シリカとマグネシアの他に、Ｙ、Ｌａ、Ｎａ、Ｋ、Ｃａ、Ｓｒ、Ｂａの酸化物が用いられていてもよい。これらの混合粉末に以下の添加剤を必要により添加して原料組成物を得る。成形助剤としては、エチレングリコール、デキストリン、脂肪酸、脂肪酸石鹸、ポリアルコールが挙げられる。有機バインダとしては、カルボキシメチルセルロース、ポリビニルアルコール、メチルセルロース、エチルセルロース等の親水性有機高分子が挙げられる。分散媒としては、水のみからなる分散媒、又は、５０体積％以上の水と有機溶剤とからなる分散媒が挙げられる。有機溶剤としては、ベンゼン、メタノール等のアルコールが挙げられる。造孔剤としては、微小中空球体であるバルーン、球状アクリル粒子、グラファイト、デンプンが挙げられる。バルーンとしては、アルミナバルーン、ガラスマイクロバルーン、シラスバルーン、フライアッシュ（ＦＡ）バルーン、ムライトバルーンが挙げられる。 In the above-mentioned mixed powder, silica and magnesia also have a role as a firing aid, but as the firing aid, in addition to silica and magnesia, oxides of Y, La, Na, K, Ca, Sr, and Ba are used. It may be used. If necessary, the following additives are added to these mixed powders to obtain a raw material composition. Examples of the molding aid include ethylene glycol, dextrin, fatty acid, fatty acid soap, and polyalcohol. Examples of the organic binder include hydrophilic organic polymers such as carboxymethyl cellulose, polyvinyl alcohol, methyl cellulose and ethyl cellulose. Examples of the dispersion medium include a dispersion medium composed of only water or a dispersion medium composed of 50% by volume or more of water and an organic solvent. Examples of the organic solvent include alcohols such as benzene and methanol. Examples of the pore-forming agent include balloons, which are minute hollow spheres, spherical acrylic particles, graphite, and starch. Examples of balloons include alumina balloons, glass micro balloons, shirasu balloons, fly ash (FA) balloons, and mullite balloons.
また、原料組成物中には、その他の成分が更に含有されていてもよい。その他の成分としては、たとえば、可塑剤、分散剤、潤滑剤が挙げられる。可塑剤としては、たとえば、ポリオキシエチレンアルキルエーテル、ポリオキシプロピレンアルキルエーテル等のポリオキシアルキレン系化合物が挙げられる。分散剤としては、たとえば、ソルビタン脂肪酸エステルが挙げられる。潤滑剤としては、たとえば、グリセリンが挙げられる。 Further, the raw material composition may further contain other components. Examples of other components include plasticizers, dispersants, and lubricants. Examples of the plasticizer include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether. Examples of the dispersant include sorbitan fatty acid ester. Examples of the lubricant include glycerin.
 （成形工程）
成形工程は、混合工程により得られた原料組成物を成形して未封止ハニカム成形体を作製する工程である。未封止ハニカム成形体は、たとえば、原料組成物を押出金型を用いて押出成形することにより作製することができる。すなわち、未封止ハニカム成形体は、ハニカム構造体の筒状の外周壁と隔壁となる部分を構成する壁部を一度に押出成形することにより作製する。また、押出成形では、ハニカム構造体の一部の形状に対応する成形体を成形してもよい。すなわち、ハニカム構造体の一部の形状に対応する成形体を成形し、それら成形体を組み合わせることによってハニカム構造体と同一形状を有するハニカム成形体を作製してもよい。 (Molding process)
The molding step is a step of molding the raw material composition obtained in the mixing step to produce an unsealed honeycomb molded body. The unsealed honeycomb molded body can be produced by, for example, extruding the raw material composition using an extrusion die. That is, the unsealed honeycomb molded body is manufactured by extruding the tubular outer peripheral wall of the honeycomb structure and the wall portion constituting the partition wall at one time. Further, in the extrusion molding, a molded body corresponding to the shape of a part of the honeycomb structure may be molded. That is, a honeycomb molded body having the same shape as the honeycomb structure may be manufactured by molding a molded body corresponding to a part of the shape of the honeycomb structure and combining the molded bodies.
図２（ａ）は、上記成形工程により作製された未封止ハニカム成形体を模式的に示す斜視図であり、図２（ｂ）は、図２（ａ）に示した未封止ハニカム成形体のＢ－Ｂ線断面図である。 FIG. 2A is a perspective view schematically showing the unsealed honeycomb molded body produced by the above molding process, and FIG. 2B is the unsealed honeycomb molded body shown in FIG. 2A. FIG. 7 is a sectional view taken along line BB of the body.
図２（ａ）及び（ｂ）に示すように、上記成形工程により、セル２２、２３の長手方向に垂直な断面形状が四角で、端面２０ａ′、２０ｂ′におけるセル２２、２３の形状も全く同じ四角形状で、セル２２、２３を隔てるセル隔壁２１を有し、全体が円柱形状の未封止ハニカム成形体２０′が作製される。 As shown in FIGS. 2 (a) and 2 (b), due to the above-described molding process, the cells 22 and 23 have a square cross section perpendicular to the longitudinal direction, and the shape of the cells 22 and 23 at the end faces 20a ′ and 20b ′ is completely zero. An unsealed honeycomb molded body 20 'having the same rectangular shape and having cell partition walls 21 separating cells 22 and 23 and having a cylindrical shape as a whole is produced.
（再成形工程）
この後、テーパー冶具を用い、未封止ハニカム成形体２０′に対し、ハニカム構造体の端部領域に相当する部分を形成するための再成形を行い、排ガス導入セル及び排ガス排出セルとなるセル２２、２３の長手方向に垂直な断面形状が端面に近づくに従って拡大され、又は、縮小され、封じられた形状の封止ハニカム成形体とする。
その際、未封止ハニカム成形体２０′の端面に水を塗布した後、上記再成形を行うことにより、後述する焼成工程後を経て端部領域の気孔率が内部領域の気孔率よりも高いハニカム構造体を製造することができる。この際、端部領域の全体に水を塗布してもよい。また、水以外に有機溶剤を用いてもよい。 (Reforming process)
Thereafter, a taper jig is used to re-form the unsealed honeycomb molded body 20 ′ to form a portion corresponding to an end region of the honeycomb structure, thereby forming an exhaust gas introduction cell and an exhaust gas discharge cell. The cross-sectional shape of 22 and 23 perpendicular to the longitudinal direction is enlarged or reduced as it approaches the end face, and the sealed honeycomb molded body has a closed shape.
At this time, by applying water to the end surface of the unsealed honeycomb molded body 20 'and then performing the above-mentioned re-molding, the porosity of the end region is higher than that of the inner region after the firing step described later. A honeycomb structure can be manufactured. At this time, water may be applied to the entire end region. Moreover, you may use an organic solvent other than water.
図３は、未封止ハニカム成形体の再成形工程の様子を模式的に示す説明図であり、図４は、未封止ハニカム成形体の再成形工程の様子を模式的に示す断面図である。
図３及び図４に示すように、支持部３３と支持部３３上に固定された基台部３１と基台部３１上に形成された多数の四角錐形状の先端部３２とを備えたテーパー冶具３０を用い、先端部３２の四角錐を構成する４つの平面３２ｂの境界部である角部３２ｃが未封止ハニカム成形体２０′の端面２０ａ′におけるセル隔壁２１の四角を構成する一の辺２１ａの真ん中に当接するように配置し、端面に水が塗布された未封止ハニカム成形体２０′の中央部分に向かってテーパー冶具３０を押し込む。 FIG. 3 is an explanatory view schematically showing a state of the remolding step of the unsealed honeycomb molded body, and FIG. 4 is a sectional view schematically showing a state of the remolding step of the unsealed honeycomb molded body. is there.
As shown in FIGS. 3 and 4, a taper including a support portion 33, a base portion 31 fixed on the support portion 33, and a large number of quadrangular pyramid-shaped tip portions 32 formed on the base portion 31. Using the jig 30, the corner portion 32c which is the boundary portion of the four flat surfaces 32b forming the quadrangular pyramid of the tip portion 32 forms the square of the cell partition wall 21 on the end surface 20a 'of the unsealed honeycomb molded body 20'. The taper jig 30 is arranged so as to come into contact with the center of the side 21a, and is pushed toward the central portion of the unsealed honeycomb molded body 20 'whose end surface is coated with water.
このとき、先端部３２が押し込まれたセル２２の端部領域に相当する部分は、セルの長手方向に垂直な断面形状が端面に近づくに従って拡大された形状となり、先端部３２が押し込まれたセル２２の上下左右に存在していたセル２３の端部領域に相当する部分は、セル２３の長手方向に垂直な断面形状が端面に近づくに従って縮小され、封じられた形状となる。また、端面から見た封止ハニカム成形体の形状は、図１（ｃ）に示すハニカム構造体１０と同じく、端面１０ａにおけるセル１２の四角が内部領域１０Ｂのセル１２の四角を４５°回転し、拡大した形状となる。
未封止ハニカム成形体の端面や端部領域に塗布する水の量を変えることにより、端部領域のセル隔壁の気孔率を調整することができる。 At this time, the portion corresponding to the end region of the cell 22 into which the tip 32 is pushed has a shape in which the cross-sectional shape perpendicular to the longitudinal direction of the cell is enlarged as it approaches the end face, and the cell into which the tip 32 is pushed The portions corresponding to the end regions of the cells 23 existing on the upper, lower, left, and right sides of the cell 22 are reduced in shape as the cross-sectional shape perpendicular to the longitudinal direction of the cells 23 approaches the end surface, and become a sealed shape. Further, the shape of the sealed honeycomb formed body viewed from the end face is the same as the honeycomb structure 10 shown in FIG. 1C, the square of the cell 12 on the end face 10a is rotated by 45 ° with respect to the square of the cell 12 of the internal region 10B. , Becomes an enlarged shape.
The porosity of the cell partition walls in the end region can be adjusted by changing the amount of water applied to the end face or the end region of the unsealed honeycomb molded body.
この再成形工程により得られた封止ハニカム成形体は、マイクロ波乾燥機、熱風乾燥機、誘電乾燥機、減圧乾燥機、真空乾燥機、凍結乾燥機等の乾燥機を用い、１００～１５０℃、大気雰囲気下で乾燥され、２５０～４００℃、酸素濃度５容積％～大気雰囲気下で脱脂される。 The sealed honeycomb molded body obtained by this remolding step is dried at 100 to 150 ° C. using a dryer such as a microwave dryer, a hot air dryer, a dielectric dryer, a reduced pressure dryer, a vacuum dryer, and a freeze dryer. Then, it is dried in an air atmosphere and degreased at 250 to 400 ° C. and an oxygen concentration of 5% by volume to an air atmosphere.
（焼成工程）
焼成工程は、再成形工程により得られた封止ハニカム成形体を１４００～１６００℃で焼成する工程である。この焼成工程では、アルミナの表面からチタニアとの反応が進行して、チタン酸アルミニウムの相が形成される。焼成は、公知の単独炉、いわゆるバッチ炉や、連続炉を用いて行うことができる。焼成温度は、１４５０～１５５０℃の範囲であることが好ましい。焼成時間は特に限定されないが、上記の焼成温度において１～２０時間保持することが好ましく、１～１０時間保持することがより好ましい。また、焼成工程は大気雰囲気下で行うことが好ましい。大気雰囲気に窒素ガスやアルゴンガス等の不活性ガスを混合することにより、酸素濃度を調整してもよい。 (Firing process)
The firing step is a step of firing the sealed honeycomb formed body obtained in the re-forming step at 1400 to 1600 ° C. In this firing step, the reaction with titania proceeds from the surface of alumina to form an aluminum titanate phase. The firing can be performed using a known single furnace, so-called batch furnace, or continuous furnace. The firing temperature is preferably in the range of 1450 to 1550 ° C. The firing time is not particularly limited, but the firing temperature is preferably maintained for 1 to 20 hours, more preferably 1 to 10 hours. In addition, it is preferable that the firing step be performed in an air atmosphere. The oxygen concentration may be adjusted by mixing an inert gas such as nitrogen gas or argon gas into the air atmosphere.
上記した混合工程、成形工程、再成形工程、及び、焼成工程を経ることにより、端部領域の気孔率が高い本発明のハニカム構造体を製造することができる。 The honeycomb structure of the present invention having a high porosity in the end region can be manufactured by undergoing the above-mentioned mixing step, molding step, remolding step, and firing step.
以下、上記実施形態をさらに具体化した実施例について説明する。
（実施例１）
まず、下記組成の原料組成物を調製した。
Ｄ５０が０．６μｍのチタニア微粉末：１１．１重量％、Ｄ５０が１３．０μｍのチタニア粗粉末：１１．１重量％、Ｄ５０が１５．９μｍのアルミナ粉末：３０．４重量％、Ｄ５０が１．１μｍのシリカ粉末：２．８重量％、Ｄ５０が３．８μｍのマグネシア粉末：１．４重量％、Ｄ５０が３１．９μｍのアクリル樹脂（造孔材）：１８．５重量％、メチルセルロース（有機バインダ）：７．１重量％、成形助剤（エステル型ノニオン）：４．７重量％、及び、イオン交換水（分散媒）：１２．９重量％からなる組成のものを混合機で混合し、原料組成物を調製した。 Hereinafter, examples in which the above embodiment is further embodied will be described.
(Example 1)
First, a raw material composition having the following composition was prepared.
Fine titania powder having D50 of 0.6 μm: 11.1% by weight, coarse titania powder having D50 of 13.0 μm: 11.1% by weight, alumina powder having D50 of 15.9 μm: 30.4% by weight, D50 of 1 .1 μm silica powder: 2.8% by weight, D50 3.8 μm magnesia powder: 1.4% by weight, D50 31.9 μm acrylic resin (pore forming material): 18.5% by weight, methylcellulose (organic A binder having a composition of 7.1% by weight, a molding aid (ester type nonion): 4.7% by weight, and ion-exchanged water (dispersion medium): 12.9% by weight are mixed with a mixer. A raw material composition was prepared.
調製した原料組成物を押出成形機に投入して押出成形を行うことにより、セルが封止されていない未封止ハニカム成形体２０′を作製した。 The prepared raw material composition was put into an extrusion molding machine and extrusion-molded to prepare an unsealed honeycomb molded body 20 'in which cells were not sealed.
未封止ハニカム成形体２０′を作製した後直ぐに、未封止ハニカム成形体２０′の両端面に水分率が３５％となるように水を塗布し、アルミ製のテーパー冶具３０を用いて、再成形を行い、本発明の封止ハニカム成形体を作製した。テーパー冶具３０としては、未封止ハニカム成形体２０′の端面２０ａを形成するための先端部３２同士の距離（図５に示すＶ：谷幅）を０．１３ｍｍに設定し、先端部３２の四角錐の平面３２ｂと、基台部３１の先端部３２が形成されている先端部形成面３１ａ（先端部底面３２ａ）に垂直な面と、の角度αを１２．５°に設定した（図３及び図４参照）。 Immediately after producing the unsealed honeycomb molded body 20 ', water is applied to both end faces of the unsealed honeycomb molded body 20' so that the water content is 35%, and the taper jig 30 made of aluminum is used. Remolding was performed to produce the sealed honeycomb molded body of the present invention. As the taper jig 30, the distance (V: valley width shown in FIG. 5) between the tip portions 32 for forming the end surface 20a of the unsealed honeycomb molded body 20 ′ is set to 0.13 mm, and the tip portion 32 is The angle α between the flat surface 32b of the quadrangular pyramid and the surface perpendicular to the tip forming surface 31a (tip bottom 32a) on which the tip 32 of the base 31 is formed is set to 12.5 ° (FIG. 3 and FIG. 4).
この後、再成形工程を経て得られた封止ハニカム成形体を大気雰囲気下、１４５０℃で１５時間保持して焼成することにより、ハニカム構造体を製造した。得られたハニカム構造体は、大きさが３４ｍｍ×３４ｍｍ×１００ｍｍ、外周壁の厚さ０．３ｍｍ、端部領域におけるセル隔壁の厚さ０．１９ｍｍ、内部領域におけるセル隔壁の厚さ０．２５ｍｍ、セルの数（セル密度）が３００個／ｉｎｃｈ２で、四角柱形状であった。なお、気孔率の測定は、下記する方法により行った。 After that, the honeycomb structure was manufactured by holding and firing the sealed honeycomb molded body obtained through the remolding step at 1450 ° C. for 15 hours in the air atmosphere. The obtained honeycomb structure had a size of 34 mm × 34 mm × 100 mm, a peripheral wall thickness of 0.3 mm, a cell partition wall thickness of 0.19 mm in the end region, and a cell partition wall thickness of 0.25 mm in the inner region. , And the number of cells (cell density) was 300 cells / inch 2 , and it was a quadrangular prism shape. The porosity was measured by the method described below.
（比較例１）
再成形を行う際に、未封止ハニカム成形体２０′の両端面に水を塗布しなかった外は、実施例１と同様にハニカム構造体を製造した。 (Comparative Example 1)
A honeycomb structure was manufactured in the same manner as in Example 1 except that water was not applied to both end surfaces of the unsealed honeycomb molded body 20 'during the remolding.
（評価試験）
実施例１及び比較例１では、得られたハニカム構造体の気孔率、及び、圧力損失を測定した。
［気孔率］
実施例１及び比較例１で得られたハニカム構造体の端部領域及び内部領域からそれぞれ気孔測定用サンプルを切り出して準備した。気孔測定用サンプルを用いて、水銀圧入法によるポロシメーター（島津製作所社製、オートポアＩＩＩ　９４２０）により気孔率を測定した。水銀圧入法にて接触角を１３０°、表面張力を４８５ｍＮ／ｍの条件とした。実施例１で得られたハニカム構造体の気孔率は、端部領域が５６％、内部領域が５４．５％であり、端部領域が１．５％気孔率が高いものであった。
比較例１では、端部領域が５４．５％、内部領域が、５４．５％と同じ値であった。 (Evaluation test)
In Example 1 and Comparative Example 1, the porosity and pressure loss of the obtained honeycomb structure were measured.
[Porosity]
Samples for pore measurement were cut out and prepared from the end region and the inner region of the honeycomb structures obtained in Example 1 and Comparative Example 1, respectively. The porosity was measured using a porosimeter (manufactured by Shimadzu Corporation, Autopore III 9420) by a mercury porosimetry method using the sample for porosity measurement. The contact angle was 130 ° and the surface tension was 485 mN / m under the mercury intrusion method. The porosity of the honeycomb structure obtained in Example 1 was 56% in the end region and 54.5% in the inner region, and the end region had a high porosity of 1.5%.
In Comparative Example 1, the end region had the same value of 54.5% and the inner region had the same value of 54.5%.
［圧力損失］
図５は、圧力損失測定方法を模式的に示す断面図である。
この圧力損失測定装置２１０は、送風機２１１の配管２１２に、実施例１で得られたハニカム構造体１０を金属ケーシング２１３内に固定して配置し、ハニカム構造体１０の前後の圧力を検出可能になるように圧力計２１４が取り付けられている。
ハニカム構造体１０は、その排ガス入口側の端部が送風機２１１の配管２１２に近い側に配置される。すなわち、排ガス入口側の端部が開口されたセルにガスが流入するように配置される。
送風機２１１から３００Ｌ／ｍｉｎのガスをハニカム構造体１０に流通させた時の圧力損失をこのハニカム構造体の圧力損失（ｋＰａ）とした。実施例１で得られた圧力損失の平均値は２．４ｋＰａであり、比較例１で得られた圧力損失の平均値は２．８ｋＰａであった。 [Pressure loss]
FIG. 5: is sectional drawing which shows the pressure loss measuring method typically.
In this pressure loss measuring device 210, the honeycomb structure 10 obtained in Example 1 is fixedly arranged in the metal casing 213 in the pipe 212 of the blower 211, and the pressure before and after the honeycomb structure 10 can be detected. A pressure gauge 214 is attached so that
The end of the honeycomb structure 10 on the exhaust gas inlet side is arranged on the side close to the pipe 212 of the blower 211. That is, the gas is arranged so as to flow into a cell having an open end on the exhaust gas inlet side.
The pressure loss when the gas of 300 L / min was passed through the honeycomb structure 10 from the blower 211 was defined as the pressure loss (kPa) of this honeycomb structure. The average value of pressure loss obtained in Example 1 was 2.4 kPa, and the average value of pressure loss obtained in Comparative Example 1 was 2.8 kPa.
１０　ハニカム構造体
１０ａ、１０ｂ　端面
１０Ａ、１０Ｃ　端部領域
１０Ｂ　内部領域
１１　セル隔壁
１２　排ガス導入セル
１３　排ガス排出セル
２０′　未封止ハニカム成形体
２０ａ′、２０ｂ′　端面　
２１　セル隔壁
２１ａ　一の辺
２２、２３　セル
３０　テーパー冶具
３１　基台部
３１ａ　先端部形成面
３２　先端部
３２ａ　先端部底面
３２ｂ　平面
３２ｃ　角部
３３　支持部 10 Honeycomb Structures 10a, 10b End Faces 10A, 10C End Regions 10B Inner Region 11 Cell Partition 12 Exhaust Gas Introducing Cells 13 Exhaust Gas Emitting Cells 20 'Unsealed Honeycomb Molded Products 20a', 20b 'End Faces
21 Cell Partition Wall 21a One Side 22, 23 Cell 30 Taper Jig 31 Base 31a Tip Forming Surface 32 Tip 32a Tip Bottom 32b Flat 32c Corner 33 Support

Claims (9)

  1. 排ガスの流路となる複数のセルを区画形成する多孔質のセル隔壁と、排ガス入口側の端面が開口され且つ排ガス出口側の端面が封じられている排ガス導入セルと、排ガス出口側の端面が開口され且つ排ガス入口側の端面が封じられている排ガス排出セルとを備えたハニカム構造体であって、
    前記排ガス導入セル及び前記排ガス排出セルは、前記排ガス導入セル及び前記排ガス排出セルの長手方向に垂直な断面形状が一定である内部領域と、前記排ガス導入セル及び前記排ガス排出セルの長手方向に垂直な断面形状が端面に近づくに従って拡大又は縮小されている端部領域とからなり、
    前記端部領域における気孔率は、前記内部領域における気孔率よりも高いことを特徴とするハニカム構造体。     Porous cell partition walls partitioning and forming a plurality of cells that form the flow path of exhaust gas, an exhaust gas introduction cell in which the end surface on the exhaust gas inlet side is opened and the end surface on the exhaust gas outlet side is closed, and the end surface on the exhaust gas outlet side is A honeycomb structure provided with an exhaust gas discharge cell which is opened and whose end face on the exhaust gas inlet side is sealed,
    The exhaust gas introduction cell and the exhaust gas discharge cell, the exhaust gas introduction cell and the internal region having a constant cross-sectional shape perpendicular to the longitudinal direction of the exhaust gas discharge cell, and vertical to the longitudinal direction of the exhaust gas introduction cell and the exhaust gas discharge cell A cross-sectional shape that is enlarged or reduced as it approaches the end surface,
    The honeycomb structure characterized in that a porosity in the end region is higher than a porosity in the inner region.
  2. 前記端部領域における気孔率は、前記内部領域における気孔率よりも０．５～５％高い請求項１に記載のハニカム構造体。 The honeycomb structure according to claim 1, wherein the porosity in the end region is higher by 0.5 to 5% than the porosity in the inner region.
  3. 前記内部領域におけるセル隔壁の気孔率は、３５～６５％である請求項１又は２に記載のハニカム構造体。 The honeycomb structure according to claim 1 or 2, wherein a porosity of the cell partition walls in the internal region is 35 to 65%.
  4. 前記端部領域における気孔の平均気孔径は、５～３０μｍである請求項１～３のいずれか１項に記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 3, wherein the average pore diameter of the pores in the end region is 5 to 30 µm.
  5. 前記端部領域のセルの長手方向の長さは、１～１０ｍｍである請求項１～４のいずれか１項に記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 4, wherein the length of the cells in the end region in the longitudinal direction is 1 to 10 mm.
  6. 前記端部領域におけるセル隔壁の厚さは、０．１～０．５ｍｍである請求項１～５のいずれか１項に記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 5, wherein the thickness of the cell partition wall in the end region is 0.1 to 0.5 mm.
  7. 前記内部領域におけるセルの長手方向に垂直な断面形状は、四角形である請求項１～６のいずれか１項に記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 6, wherein a cross-sectional shape of the cells in the inner region, which is perpendicular to a longitudinal direction, is a quadrangle.
  8. 前記ハニカム構造体は、外周に外周壁を有する一のハニカム焼成体により構成されている請求項１～７のいずれか１項に記載のハニカム構造体。 The honeycomb structure according to any one of claims 1 to 7, wherein the honeycomb structure is made of one honeycomb fired body having an outer peripheral wall on the outer periphery.
  9. 前記ハニカム焼成体は、コージェライト、又は、チタン酸アルミニウムからなる請求項１～８のいずれか１項に記載のハニカム構造体。
     
          The honeycomb structure according to any one of claims 1 to 8, wherein the honeycomb fired body is made of cordierite or aluminum titanate.

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JP2003049631A (en) * 2001-08-08 2003-02-21 Toyota Motor Corp Exhaust emission control device
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JP2003047813A (en) * 2001-08-08 2003-02-18 Toyota Motor Corp Exhaust emission control apparatus
JP2003049631A (en) * 2001-08-08 2003-02-21 Toyota Motor Corp Exhaust emission control device
JP2003236322A (en) * 2001-12-03 2003-08-26 Hitachi Metals Ltd Ceramic honeycomb filter
JP2006272318A (en) * 2005-03-01 2006-10-12 Denso Corp Manufacturing method of exhaust gas purifying filter
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