JP2015131255A - honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure having low pressure drop, excellent in service durability.SOLUTION: A honeycomb structure 100 includes a cylindrical honeycomb structural part 10 having partition walls 1 which define a plurality of cells 2 extending from an inlet end face 11 to an outlet end face 12 of a fluid flow channel. The thickness Aof the partition wall 1a in the range from the inlet end face 11 of the honeycomb structural part 10 to at least 5% or more and 50% or less of the total length L1 of the honeycomb structural part 10 is thinner by 0.051 mm or more than the thickness Aof the partition wall 1b on the outlet side at the outlet end face 12 of the honeycomb structural part 10.

Description

  The present invention relates to a honeycomb structure. More specifically, the present invention relates to a honeycomb structure having low pressure loss and excellent durability.

Exhaust gas discharged from internal combustion engines such as automobile engines contains harmful substances such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO _X ). Catalytic reactions are widely used to reduce such harmful substances and purify exhaust gas. For exhaust gas purification using a catalyst, a honeycomb structure having a catalyst supported thereon is widely used.

  In the honeycomb structure, a honeycomb structure (honeycomb structure) is formed by partition walls that partition and form cells serving as fluid flow paths. Since the catalyst is supported on the partition walls of the honeycomb structure, the surface area of the catalyst per volume in the catalyst body is increased, so that the exhaust gas and the catalyst come into contact with each other at a high frequency. As a result, in the honeycomb structure on which the catalyst is supported, the catalytic reaction is promoted, and the exhaust gas can be purified with high efficiency.

  A honeycomb structure having a lower pressure loss is required for fuel efficiency regulations that are becoming stricter year by year. For the pressure loss of the honeycomb structure, the thickness of the partition walls and the cell pitch of the honeycomb structure are dominant. Here, the structure including the partition wall thickness and the cell pitch in the honeycomb structure may be referred to as a “cell structure”. In recent years, there has been proposed a honeycomb structure in which the partition walls that form cells serving as exhaust gas flow paths change in thickness along the axis from the exhaust gas inflow end surface to the outflow end surface (for example, (See Patent Documents 1 and 2).

Japanese translation of PCT publication No. 2004-511335 Special table 2009-532196 gazette

  As described above, the cell structure is dominant with respect to the pressure loss of the honeycomb structure, but when the pressure loss of the honeycomb structure is lowered, the durability of the honeycomb structure may be lowered. For example, if the thickness of the partition wall of the honeycomb structure is reduced in order to reduce the pressure loss of the honeycomb structure, the durability of the honeycomb structure is deteriorated. Thus, reducing the pressure loss of the honeycomb structure and improving the durability of the honeycomb structure are in a trade-off relationship, and it has been extremely difficult to solve both simultaneously.

In addition, a purification method using an SCR catalyst is effective for purification of nitrogen oxide (NO _x ) contained in exhaust gas discharged from an engine or the like. For this reason, the SCR catalyst is widely used for purification of exhaust gas (specifically, purification of nitrogen oxides contained in the exhaust gas). “SCR” is an abbreviation for “Selective Catalytic Reduction”. The “SCR catalyst” means a catalyst that selectively reduces a component to be purified by a reduction reaction. In the SCR catalyst, the amount of the SCR catalyst greatly affects the purification performance. For this reason, in order to improve the purification performance by the SCR catalyst, a large amount of catalyst is required. When a large amount of the SCR catalyst is supported on the partition walls of the honeycomb structure, a thick catalyst layer made of the SCR catalyst is deposited on the surface of the partition walls. Such a catalyst layer has a problem of reducing the hydraulic diameter of the exhaust gas flow path constituted by the cells and increasing the pressure loss of the honeycomb structure.

  The present invention has been made in view of such problems, and provides a honeycomb structure having low pressure loss and excellent durability.

  According to the present invention, the following honeycomb structure is provided.

[1] A cylindrical honeycomb structure portion having partition walls that form a plurality of cells extending from an inflow end surface to an outflow end surface serving as a fluid flow path, and from the inflow end surface of the honeycomb structure portion, The partition wall thickness A _{in in} the range of at least 5% and up to 50% of the total length is 0.051 mm or more thinner than the partition wall thickness A _out on the outflow end face of the honeycomb structure part, Honeycomb structure.

[2] The honeycomb structure according to [1], wherein the partition wall is formed by supporting a catalyst on a partition wall base material made of a porous material.

[3] The honeycomb structure according to [2], wherein the catalyst is supported on the partition wall base material at least in a range of more than 50% of the total length of the honeycomb structure portion.

[4] In the range from 5% to 50% of the total length of the honeycomb structure part from the inflow end surface and the range of more than 50% of the total length of the honeycomb structure part, The honeycomb structure according to [2] or [3], wherein the thickness of the catalyst layer constituted by the catalyst is different.

[5] The thickness of the partition wall base material in the range from 5% to 50% of the total length of the honeycomb structure portion from the inflow end surface is the thickness of the partition wall base material in the inflow end surface of the honeycomb structure portion. The honeycomb structure according to any one of [2] to [4], which is thinner than 0.051 mm by comparison.

[6] The honeycomb structure according to any one of [1] to [5], wherein an overall length of the honeycomb structure portion is 50 mm or more.

In the honeycomb structure of the present invention, the partition wall thickness A _{in in} a predetermined range from the inflow end face of the honeycomb structure part is 0.051 mm or more thinner than the partition wall thickness A _out in the outflow end face of the honeycomb structure part. It has become a thing. The predetermined range is a range from the inflow end face of the honeycomb structure part to at least 5% and 50% or less of the total length of the honeycomb structure part. The honeycomb structure configured as described above has low pressure loss and excellent durability.

1 is a perspective view schematically showing an embodiment of a honeycomb structure of the present invention. It is a top view which shows typically the inflow end surface of one Embodiment of the honeycomb structure of this invention. It is a top view which shows typically the outflow end surface of one Embodiment of the honeycomb structure of this invention. 1 is a cross-sectional view schematically showing a cross section parallel to a cell extending direction of an embodiment of a honeycomb structure of the present invention. It is a perspective view which shows typically other embodiment of the honeycomb structure of this invention. It is a top view which shows typically the inflow end surface of other embodiment of the honeycomb structure of this invention. It is a top view which shows typically the outflow end surface of other embodiment of the honeycomb structure of this invention. It is sectional drawing which shows typically the cross section parallel to the cell extending direction of other embodiment of the honeycomb structure of this invention. FIG. 6 is a perspective view schematically showing still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an outflow end surface of still another embodiment of the honeycomb structure of the present invention. [Fig. 6] Fig. 6 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction of still another embodiment of the honeycomb structure of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the present invention.

(1) Honeycomb structure:
First, an embodiment of the honeycomb structure of the present invention will be described. As shown in FIGS. 1 to 4, the honeycomb structure of the present embodiment is a tubular honeycomb having partition walls 1 that partition and form a plurality of cells 2 extending from an inflow end surface 11 to an outflow end surface 12 serving as a fluid flow path. A honeycomb structure 100 including the structure portion 10. In the honeycomb structure 100, the thickness A _in of the partition wall 1 a in a predetermined range from the inflow end surface 11 of the honeycomb structure portion 10 is 0 as compared with the thickness A _out of the partition wall 1 b in the outflow end surface 12 of the honeycomb structure portion 10. .051mm or thinner. The predetermined range is a range from the inflow end face 11 of the honeycomb structure 10 to at least 5% and 50% or less of the total length of the honeycomb structure 10 (for example, the total length L1 in FIG. 4). Hereinafter, the honeycomb structure 100 of the present embodiment will be described assuming that the total length of the honeycomb structure portion 10 is “the total length L1”. In the honeycomb structure 100 shown in FIG. 4, the thickness A _in of the partition wall 1a _in the range of the length L1 _in from the inflow end face 11 of the honeycomb structure portion 10 is less than the thickness A _out of the partition wall 1b. It is thinner than 051 mm.

  Here, FIG. 1 is a perspective view schematically showing one embodiment of the honeycomb structure of the present invention. FIG. 2 is a plan view schematically showing an inflow end surface of one embodiment of the honeycomb structure of the present invention. Fig. 3 is a plan view schematically showing the outflow end face of one embodiment of the honeycomb structure of the present invention. FIG. 4 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction of one embodiment of the honeycomb structure of the present invention.

The “full length of the honeycomb structure portion” is the length from the inflow end surface 11 to the outflow end surface 12 of the honeycomb structure portion 10. Further, “length L1 _in ” _in FIG. 4 is a length from the inflow end face 11 of the honeycomb structure portion 10 and is a length satisfying a relationship of 0.05L1 ≦ L1 _in ≦ 0.5L1. In Figure 4, the "length _{L1 out"} is the length obtained by subtracting the "length _{L1 in"} from "full-length L1 'of the honeycomb structural portion 10. That is, “length L1 _out ” is the length from the outflow end face 12 of the honeycomb structure 10 and satisfies the relationship of 0.5L1 ≦ L1 _out ≦ 0.95L1.

Hereinafter, _in the range from the inflow end face 11 to the length L1 _in , the partition 1a whose thickness is 0.051 mm or more thinner than the partition 1b in the outflow end face 12 is referred to as “inflow side partition 1a” or “thin It may be referred to as “wall partition wall 1a”. In the range from the outflow end face 12 to the length L1 _out , the partition wall 1b whose thickness is larger than the inflow side partition wall 1a may be referred to as “outflow side partition wall 1b” or “thick wall partition wall 1b”.

In the honeycomb structure 100 of the present embodiment, the thickness A _in of the inflow side partition wall 1a is 0.051 mm or more thinner than the thickness A _out of the partition wall 1b in the outflow end face 12, so that it is durable. The pressure loss can be reduced while maintaining the properties. That is, by reducing the thickness only A _in the inflow-side partition wall 1a, by relatively thick thickness A _out of the partition wall 1b of the range other than the inflow-side partition wall 1a, while effectively suppressing a decrease in durability The pressure loss can be reduced. Further, such a honeycomb structure 100 is used in comparison with a conventional honeycomb structure when used as a catalyst carrier for supporting a catalyst for purifying exhaust gas or as a filter for purifying exhaust gas on which the catalyst is supported. Thus, a larger amount of catalyst can be supported.

In addition, even if the thickness A _in of the inflow side partition wall 1a is thinner than the thickness A _out of the partition wall 1b in the outflow end surface 12 by less than 0.051 mm, a sufficient pressure loss reduction effect can be achieved. It is difficult. The thickness A _in of the inflow side partition wall 1a is preferably 0.051 to 0.102 mm thinner than the thickness A _out of the partition wall 1b at the outflow end face 12, and is 0.051 to 0.076 mm thinner. More preferably.

  The inflow side partition wall 1a exists in a range from the inflow end face 11 of the honeycomb structure portion 10 to at least 5% and 50% or less of the total length L1 of the honeycomb structure portion 10. When the inflow side partition wall 1a exists only in the range of less than 5% of the total length L1 of the honeycomb structure portion 10 from the inflow end face 11 of the honeycomb structure portion 10, it is possible to achieve a sufficient pressure loss reduction effect. Have difficulty. Further, when the inflow side partition wall 1a is also present in a range exceeding 50% of the total length L1 of the honeycomb structure portion 10 from the inflow end face 11 of the honeycomb structure portion 10, the durability of the honeycomb structure 100 is improved. May fall. The inflow side partition wall 1a is preferably present in a range of at least 10% and up to 50% of the total length L1 of the honeycomb structure portion 10, and is present in a range of at least 20% and up to 40%. More preferably.

In the honeycomb structure 100, the thickness A _out of the outflow side partition wall 1b existing outside the range where the inflow side partition wall 1a is disposed is 0.051 mm or more thicker than the thickness A _in of the inflow side partition wall 1a. Preferably there is. That is, the thickness A _out of the partition wall 1b in the range of the length L1 _out from the outflow end face 12 of the honeycomb structure 10 is 0.051 mm or more thicker than the thickness A _in of the inflow side partition wall 1a. Is preferred.

The honeycomb structure 10 may have an outer peripheral wall 3 disposed on the outermost periphery so as to surround the partition wall 1. By having such an outer peripheral wall 3, the honeycomb structure 100 can be easily accommodated in the can of the exhaust gas purification apparatus. The honeycomb structure 100 of the present embodiment is effective when the total length L1 of the honeycomb structure portion 10 is 50 mm or more, and particularly effective when it is 100 to 254 mm. If the total length L1 of the honeycomb structure 10 is less than 50 mm, the effect of reducing the pressure loss may be difficult to be exhibited. In particular, in the case of the honeycomb structure portion 10 having a thickness of 50 mm, the inflow side partition wall 1a _in which the partition wall thickness _Ain is reduced is disposed in a range of at least 2.5 mm from the inflow end face 11. If the arrangement range of the inflow side partition wall 1a is less than 2.5 mm from the inflow end surface 11, the effect of reducing the pressure loss may be difficult to be exhibited. In order to obtain the effect of reducing the pressure loss more favorably, it is more preferable that the inflow side partition wall 1a has an arrangement range of 5 mm or more from the inflow end surface 11 and 10 mm or more from the inflow end surface 11. It is particularly preferable.

  The partition walls constituting the honeycomb structure part may be ones in which a catalyst is supported on a partition base material made of a porous material. That is, in the honeycomb structure 100 shown in FIG. 1 to FIG. 4, the partition wall 1 is configured by a partition wall base material made of a porous material, and the partition wall 1 configured by the partition wall base material is an inflow side partition wall 1 a. And the outflow side partition wall 1b. The honeycomb structure of the present invention may be a honeycomb structure 200 shown in FIGS. Here, FIG. 5 is a perspective view schematically showing another embodiment of the honeycomb structure of the present invention. FIG. 6 is a plan view schematically showing an inflow end surface of another embodiment of the honeycomb structure of the present invention. FIG. 7 is a plan view schematically showing the outflow end face of another embodiment of the honeycomb structure of the present invention. FIG. 8 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction of another embodiment of the honeycomb structure of the present invention.

A honeycomb structure 200 shown in FIGS. 5 to 8 includes a tubular honeycomb structure portion 40 having partition walls 21 that partition and form a plurality of cells 32 extending from an inflow end surface 41 to an outflow end surface 42 serving as a fluid flow path. Is. In addition, about the honeycomb structure part 40 in the honeycomb structure 200 of this embodiment, let the full length be "full length L2." Then, the thickness B _in of the partition wall 31a in a predetermined range from the inflow end surface 41 of the honeycomb structure portion 40 is 0.051 mm or more thinner than the thickness B _out of the partition wall 31b in the outflow end surface 42 of the honeycomb structure portion 40. It has become a thing. The predetermined range is a range from the inflow end face 41 of the honeycomb structure 40 to at least 5% and 50% or less of the total length L2 of the honeycomb structure 40. In the honeycomb structure 200 shown in FIG. 8, the thickness B _in of the partition wall 31a _in the range from the inflow end face 41 of the honeycomb structure portion 40 to the length L2 _in is 0. 0 as compared with the thickness B _out of the partition wall 31b. It is thinner than 051 mm.

In the honeycomb structure 200 shown in FIGS. 5 to 8, the partition walls 31 constituting the honeycomb structure portion 40 are obtained by supporting the catalyst 46 on the partition base material 45 made of a porous material. That is, the partition walls 31 in the honeycomb structure 200 of the present embodiment are configured by the partition base material 45 and the catalyst 46. Here, the partition wall 31a may be referred to as an “inflow side partition wall 31a” or a “thin wall partition wall 31a”. The partition wall 31b may be referred to as “outflow side partition wall 31b” or “thick wall partition wall 31b”. The inflow side partition wall 31 a is configured by a partition wall base material 45. The thickness B _in of the inflow side partition wall 31a corresponds to the thickness of the partition wall base material 45. The outflow side partition wall 31 b includes a partition wall base 45 and a catalyst 46 on the surface of the partition wall base 45. The thickness B _out of the outflow side partition wall 31 b corresponds to the sum of the thickness of the partition wall base material 45 and the thickness of the catalyst layer formed by the catalyst 46.

Like the honeycomb structure 200 shown in FIG. 5 to FIG. 8, the outflow side partition wall 31 b in which the partition wall 31 becomes thicker is constituted by the partition wall base material 45 and the catalyst 46, so that the thickness of the inflow side partition wall 31 a is increased. while thin B _in, it is possible to increase the thickness _{B out} of the outflow-side partition wall 31b. For this reason, pressure loss can be reduced while maintaining the durability of the honeycomb structure 200. Further, since the catalyst 46 is preferentially supported on the outflow side partition wall 31b, in the honeycomb structure 200 on which the catalyst 46 is supported, the amount of the catalyst 46 supported can be increased while suppressing an increase in pressure loss. Can do.

Examples of the catalyst 46 include various catalysts such as a three-way catalyst, a NO _X storage reduction catalyst, an oxidation catalyst, and an SCR catalyst such as a NO _X selective reduction catalyst. Examples of the method for supporting the catalyst 46 include a method using a conventionally known catalyst slurry. In addition to the catalyst, the catalyst slurry may contain a noble metal, a catalyst auxiliary, a noble metal holding material, and the like. Examples of the noble metal include platinum, rhodium, and palladium. Examples of the catalyst auxiliary include alumina, zirconia, and ceria.

  In the honeycomb structure 200 shown in FIGS. 5 to 8, the catalyst 46 may be supported on the partition wall base material 45 at least in a range of more than 50% of the total length L <b> 2 of the honeycomb structure portion 40. In this honeycomb structure 200, the catalyst 46 is supported only on the outflow side partition wall 31b, and the outflow side partition wall 31b is thick. However, the catalyst 46 is also supported on the inflow side partition wall 31a. Also good. At this time, it is supported on the partition wall base material 45 in the range from 5% to 50% of the total length L2 of the honeycomb structure portion 40 from the inflow end face 41 and in the range of more than 50% of the total length L2 of the honeycomb structure portion 40. The thickness of the catalyst layer constituted by the catalyst 46 may be different. In particular, the thickness of the catalyst layer formed by the catalyst 46 supported by the outflow side partition wall 31b is larger than the thickness of the catalyst layer formed by the catalyst 46 supported by the inflow side partition wall 31a. It is preferable that the thickness is 0.051 mm or more per contact. Here, “thickness of 0.051 mm or more per partition 31” is formed by the catalyst 46 supported on both surfaces of the partition substrate 45 when the catalyst 46 is supported on both surfaces of the partition substrate 45. That is, the total thickness of the catalyst layers is 0.051 mm or more.

  In the honeycomb structure 200 shown in FIGS. 5 to 8, an example in which the catalyst 46 is supported on both surfaces of the partition wall base material 45 of the outflow side partition wall 31 b is shown, but the partition wall base material 45 of the outflow side partition wall 31 b is shown. The catalyst 46 may be supported on one side of the.

  In the honeycomb structure 200 shown in FIGS. 5 to 8, the thickness of the partition wall base material 45 is constant over the entire length L <b> 2 of the honeycomb structure portion 40. The total length L2 may be partially different. For example, although not shown, the thickness of the partition wall base material in the range from 5% to 50% of the total length L2 of the honeycomb structure portion from the inflow end surface is the thickness of the partition wall base material at the outflow end surface of the honeycomb structure portion. In comparison, it may be thinner by 0.051 mm or more. In the honeycomb structure portion configured as described above, a honeycomb structure satisfying the configuration of the present invention can be obtained when the catalyst is supported with a uniform thickness throughout the length direction of the partition wall substrate.

  In the honeycomb structure of the present embodiment, plugging portions disposed in openings of predetermined cells (first cells) on the inflow end surface and remaining cells (second cells) on the outflow end surface are provided. You may have. The first cells and the second cells are preferably arranged alternately. Then, it is preferable that a checkered pattern is formed on both end faces of the honeycomb structure by the plugged portions and the “cell openings”. The material of the plugging portion is preferably a material that is preferable as a material of the partition wall. The material of the plugging portion and the material of the partition wall may be the same material or different materials. Such a honeycomb structure can be suitably used as a filter for collecting particulate matter in exhaust gas.

  For example, the honeycomb structure of the present invention may be a honeycomb structure 300 shown in FIGS. Here, FIG. 9 is a perspective view schematically showing still another embodiment of the honeycomb structure of the present invention. FIG. 10 is a plan view schematically showing an inflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 11 is a plan view schematically showing the outflow end surface of still another embodiment of the honeycomb structure of the present invention. FIG. 12 is a cross-sectional view schematically showing a cross section parallel to the cell extending direction of still another embodiment of the honeycomb structure of the present invention. In the honeycomb structure 300 shown in FIGS. 9 to 12, the same reference numerals are given to the same constituent elements as in the honeycomb structure 200 shown in FIGS. 5 to 8, and description thereof may be omitted.

A honeycomb structure 300 shown in FIGS. 9 to 12 includes a tubular honeycomb structure portion 40 having partition walls 21 that partition and form a plurality of cells 32 extending from an inflow end surface 41 to an outflow end surface 42 serving as a fluid flow path. Is. Then, the thickness B _in of the partition wall 31a in a predetermined range from the inflow end surface 41 of the honeycomb structure portion 40 is 0.051 mm or more thinner than the thickness B _out of the partition wall 31b in the outflow end surface 42 of the honeycomb structure portion 40. It has become a thing. The predetermined range is a range from the inflow end face 41 of the honeycomb structure 40 to at least 5% and 50% or less of the total length L2 of the honeycomb structure 40. The honeycomb structure 300 further includes a plugging portion 47 disposed in the opening portion of the predetermined cell 32 on the inflow end surface 41 and the opening portion of the remaining cell 32 on the outflow end surface 42. Even in a honeycomb structure provided with such plugging portions 47, pressure loss can be reduced by adopting the above configuration. For example, when the thickness B _in of the inflow side partition wall 31a is made 0.051 mm thinner than the thickness B _out of the outflow side partition wall 31b _in the range of 20% of the total length L2 from the inflow end surface 41, the pressure loss of the honeycomb structure Was confirmed to be reduced by 10%. The honeycomb structure to be compared in the above confirmation is a honeycomb structure in which the partition wall thickness of the honeycomb structure part is the same as the thickness B _out of the outflow side partition wall 31b of the honeycomb structure over the entire length. is there.

  The partition wall 1 of the honeycomb structure 100 shown in FIGS. 1 to 4 is preferably a porous one made of ceramic. Here, the partition walls 1 of the honeycomb structure 100 shown in FIGS. 1 to 4 are those on which no catalyst is supported, and correspond to, for example, the partition wall base material 45 of the honeycomb structure portion 40 in FIGS. 5 to 8. It is. The material of the partition wall 1 is selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. It is preferable that it consists of at least one kind. By using such a material, a honeycomb structure having excellent heat resistance is obtained. The partition may be made of a material containing as a main component at least one selected from the above group. Here, the “main component” means that the component contained in the material constituting the partition wall 1 is 70% by mass or more. The partition walls are preferably made of a material containing 80% by mass or more, more preferably 90% by mass or more, of at least one selected from the above group.

  1 to 4 includes the porous partition wall 1 and the outer peripheral wall 3 disposed on the outermost periphery so as to surround the partition wall 1 as described above. The outer peripheral wall 3 may be formed together with the partition walls 1 when the honeycomb formed body is extruded in the process of manufacturing the honeycomb structure 10. Further, it is not necessary to form the outer peripheral wall at the time of extrusion molding. For example, the outer peripheral wall 3 can be formed by coating a ceramic material on the outer peripheral portion of the partition wall 1 that defines the cell 2. Further, the outer peripheral portion of the honeycomb structure 10 can be ground and removed once, and the outer peripheral wall 3 can be formed by applying a ceramic material so as to surround the partition wall 1.

  There is no restriction | limiting in particular about the shape of a honeycomb structure part. For example, examples of the shape of the honeycomb structure part include a cylindrical shape (cylindrical shape) of the end surface of the honeycomb structure part, a cylindrical shape of the oval shape of the end face, and a cylindrical shape of the end face. Examples of the polygon include a quadrangle, a pentagon, a hexagon, a heptagon, and an octagon. 1 to 4 show examples in which the honeycomb structure portion 10 has a cylindrical shape with a circular end surface.

  The thickness of the outflow side partition wall is preferably 0.076 to 0.508 μm, more preferably 0.102 to 0.381 μm, and particularly preferably 0.152 to 0.381 μm. By setting the thickness of the inflow side partition wall within the above numerical range, it is possible to suppress the deterioration of the pressure loss of the honeycomb structure while maintaining the strength of the honeycomb structure. In addition, the thickness of the inflow side partition is 0.051 mm or more thinner than the thickness of the outflow side partition.

  Examples of the method for making the thickness of the inflow side partition wall thinner than the thickness of the outflow side partition wall include the following methods (1) to (6). In the following methods (1) to (4), the thickness of the partition wall is previously increased so as to be approximately the same as the thickness of the outflow side partition wall, and the inflow side partition wall is subsequently thinned. It is. The following methods (5) and (6) are methods in which the thickness of the partition wall is reduced in advance to be the same as the thickness of the inflow side partition wall, and the thickness of the outflow side partition wall is increased later. . (1) A method of reducing the thickness of the inflow side partition by grinding the surface of the partition where the inflow side partition is disposed with a grinding tool such as a file. (2) A method in which a solution such as an acid is applied to the partition wall where the inflow side partition wall is disposed, and the partition wall is partially eroded to reduce the thickness of the inflow side partition wall. (3) A method of reducing the thickness of the inflow side partition wall by forming the honeycomb structure portion by a method such as extrusion and then extending a portion where the inflow side partition wall is disposed. (4) A method in which the surface of the partition wall where the inflow side partition wall is disposed is sandblasted to reduce the thickness of the inflow side partition wall. (5) A method of increasing the thickness of the outflow side partition by disposing a film of the same material or different material as the partition on the surface of the partition where the outflow side partition is disposed. (6) A method in which the catalyst is supported on the surface of the partition wall where the outflow side partition wall is disposed to increase the thickness of the outflow side partition wall. In addition, about the method made thinner than the thickness of an outflow side partition, it is not limited to the method of said (1)-(6).

The cell density of the honeycomb structure part is preferably 16 to 186 cells / cm ² . By setting the cell density within the above numerical range, an increase in pressure loss can be effectively prevented. Moreover, when the catalyst is supported on the partition walls of the honeycomb structure (in other words, the honeycomb structure portion), high purification performance can be obtained. The cell density of the honeycomb structure portion means the number of cells per unit area in a cross section perpendicular to the cell extending direction. Cell density of the honeycomb structure section, further preferably from 23 to 93 amino / cm ^2, and particularly preferably 31 to 62 pieces / cm ^2.

  The porosity of the partition walls is preferably 25 to 90%, more preferably 30 to 80%, and particularly preferably 35 to 75%. When the porosity is less than 25%, the pressure loss of the honeycomb structure may increase. If the porosity is higher than 90%, the strength of the honeycomb structure may be lowered. The porosity of the partition walls can be measured with a mercury porosimeter. As a mercury porosimeter, the product name: Autopore 9500 made by Micromeritics can be mentioned. The porosity of the partition wall is a porosity measured in a state where no catalyst is supported.

  Examples of the shape of the cell in the cross section orthogonal to the cell extending direction include a quadrangle, a hexagon, an octagon, a circle, and a combination thereof. Among squares, squares and rectangles are preferable.

  The size in the cross section perpendicular to the direction extending from the inflow end surface 11 to the outflow end surface 12 of the honeycomb structure 100 is not particularly limited, and optimal purification is achieved when the honeycomb structure 100 is used in various exhaust gas purification apparatuses. What is necessary is just to select suitably so that performance may be acquired. In the honeycomb structure 100 of the present embodiment, when the shape of the cross section is circular, the diameter of the cross section is preferably 50 to 400 mm, and more preferably 70 to 360 mm.

  Although not shown, the honeycomb structure may be a segment structure honeycomb structure. Specifically, examples of the honeycomb structure having a segment structure include a honeycomb structure in which a plurality of application lengths L are joined in a state of being arranged adjacent to each other such that their side faces face each other. it can. The honeycomb segment has a porous partition wall defining a plurality of cells serving as a fluid flow path extending from the first end surface to the second end surface, and an outer wall disposed so as to surround the partition wall. An outer peripheral wall is disposed on the outermost periphery of the joined body obtained by joining a plurality of honeycomb segments. In addition, by processing the outer peripheral portion of the joined body obtained by joining a plurality of honeycomb segments by grinding or the like, and making the shape of the cross section perpendicular to the cell extending direction circular or the like, the ceramic material is applied to the outermost periphery. An outer peripheral wall may be arranged. Even in such a so-called segment structure honeycomb structure, it is possible to obtain the same effects as the so-called monolithic honeycomb structure as shown in FIGS.

  The outer peripheral wall may be made of the same material as the partition wall or may be made of a different material. For example, the outer peripheral wall is at least selected from the group consisting of silicon carbide, silicon-silicon carbide based composite material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite based composite material, lithium aluminum silicate, and aluminum titanate. It is preferable that it consists of 1 type. By constituting in this way, a honeycomb structure having excellent heat resistance is obtained.

(2) Manufacturing method of honeycomb structure:
Next, the manufacturing method of the honeycomb structure of the present invention will be described. However, the method for manufacturing the honeycomb structure of the present invention is not limited to the following manufacturing method.

  First, when manufacturing a honeycomb structure, a forming raw material containing a ceramic raw material is mixed and kneaded to obtain a clay. This clay is for producing a honeycomb structure. The ceramic raw material is selected from the group consisting of silicon carbide, silicon-silicon carbide composite material, cordierite forming raw material, cordierite, mullite, alumina, spinel, silicon carbide-cordierite composite material, lithium aluminum silicate, and aluminum titanate. It is preferable to use at least one selected. The cordierite forming raw material is a ceramic raw material blended so as to have a chemical composition that falls within a range of 42 to 56% by mass of silica, 30 to 45% by mass of alumina, and 12 to 16% by mass of magnesia. The cordierite forming raw material is fired to become cordierite.

  The forming raw material is preferably prepared by further mixing a ceramic raw material with a dispersion medium, an organic binder, an inorganic binder, a surfactant, a pore former, and the like. The composition ratio of each raw material is not particularly limited, and is preferably a composition ratio in accordance with the structure and material of the honeycomb structure part to be manufactured.

  Water can be used as the dispersion medium. It is preferable that the addition amount of a dispersion medium is 10-30 mass parts with respect to 100 mass parts of ceramic raw materials.

  The organic binder is preferably methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, or a combination thereof. As for the addition amount of an organic binder, 0.5-5 mass parts is preferable with respect to 100 mass parts of ceramic raw materials.

  As the surfactant, ethylene glycol, dextrin, fatty acid soap, polyalcohol and the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type. The addition amount of the surfactant is preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  As the pore former, resin particles, starch, carbon and the like can be used. The pore former is for forming pores in the partition walls of the honeycomb structure to be produced. The amount of pore former added is preferably adjusted as appropriate in consideration of the average pore diameter and porosity of the partition walls of the honeycomb structure to be produced.

  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.

  Next, the obtained clay is formed to form a cylindrical honeycomb formed body. The honeycomb formed body preferably has partition walls and outer peripheral walls that partition and form a plurality of cells. A method for forming a kneaded clay to form a honeycomb formed body is not particularly limited, and a known forming method such as extrusion molding or injection molding can be used. For example, a preferable example includes a method of extrusion molding using a die for extrusion molding having a desired cell shape, partition wall thickness, and cell density. When adopting the methods (1) to (4) of the method for reducing the thickness of the outflow side partition wall described above to reduce the thickness of the inflow side partition wall later, the thickness of the partition wall of the honeycomb formed body However, it is preferable that the partition wall has the thickness of the outflow side partition wall after firing. On the other hand, when adopting the methods (5) and (6) of the method of making it thinner than the thickness of the outflow side partition wall and increasing the thickness of the outflow side partition wall later, the thickness of the partition wall of the honeycomb formed body However, it is preferable that the partition wall has the thickness of the inflow side partition wall after firing.

  In the case of performing the method (3) of the method of making the thickness smaller than the thickness of the outflow side partition wall described above, the thickness of the partition wall that becomes the inflow side partition wall after firing is reduced after the honeycomb formed body is manufactured. preferable. That is, after extruding the honeycomb formed body, the portion of the honeycomb formed body where the inflow-side partition walls are disposed may be pulled and the portion may be extended to reduce the thickness of the inflow-side partition walls.

  Next, the obtained honeycomb formed body is dried. Examples of the drying method include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying, and the like. Among them, it is preferable to perform dielectric drying, microwave drying, or hot air drying alone or in combination.

  Next, the honeycomb formed body is fired. Prior to firing the honeycomb formed body, the honeycomb formed body is preferably calcined. Calcination is performed for degreasing. There is no restriction | limiting in particular about the method of calcination. For example, it is sufficient that at least a part of the organic matter in the honeycomb formed body can be removed. Examples of the organic material include an organic binder, a surfactant, and a pore former. The combustion temperature of the organic binder is about 100 to 300 ° C. For this reason, calcination is preferably performed at about 200 to 1000 ° C. for about 10 to 100 hours in an oxidizing atmosphere.

  The firing of the honeycomb formed body is performed in order to sinter and densify the forming raw material constituting the calcined formed body to ensure a predetermined strength. Since the firing conditions differ depending on the type of molding raw material, appropriate conditions may be selected according to the type. For example, when the cordierite forming raw material is used, the firing temperature is preferably 1350 to 1440 ° C. The firing time is preferably 3 to 10 hours as a keep time at the maximum temperature. Examples of the apparatus for performing calcination and main firing include an electric furnace and a gas furnace.

  After firing the honeycomb formed body, the methods (1), (2), and (4) to (6) are performed among the methods (1) to (6) for reducing the thickness of the above-described outflow side partition wall. Thereby, the thickness of the inflow side partition can be reduced, or the thickness of the outflow side partition can be increased. For example, the surface of the partition wall where the inflow side partition wall is disposed may be shaved with a grinding tool such as a file to reduce the thickness of the inflow side partition wall. A solution such as an acid may be applied to the partition wall where the inflow side partition wall is disposed, and the partition wall may be partially eroded to reduce the thickness of the inflow side partition wall. The surface of the partition wall where the inflow side partition wall is disposed may be sandblasted to reduce the thickness of the inflow side partition wall. The thickness of the outflow side partition may be increased by disposing a film of the same material as or different from the partition wall on the surface of the partition where the outflow side partition is disposed. The catalyst may be supported on the surface of the partition wall where the outflow side partition wall is disposed to increase the thickness of the outflow side partition wall.

  As described above, a honeycomb structure including a cylindrical honeycomb structure portion having porous partition walls can be manufactured. In addition, the plugging material may be filled into the inflow side end portions of predetermined cells and the outflow side end portions of the remaining cells of the honeycomb structure portion to form plugging portions. About the method of forming a plugging part, it can carry out according to the conventionally well-known manufacturing method of the honeycomb structure provided with the plugging part.

  A method for increasing the thickness of the outflow side partition wall by supporting the catalyst on the surface of the partition wall where the outflow side partition wall is disposed is not particularly limited. It is preferable to immerse the portion where the outflow side partition wall is disposed. By comprising in this way, a catalyst slurry can be applied only to the part by which the outflow side partition of a honeycomb structure is arrange | positioned. As another method, a method of forming a catalyst layer by circulating a catalyst slurry on a carrier is preferable. Here, the “support” refers to a honeycomb structure portion having porous partition walls. The catalyst slurry can be applied by pouring the catalyst slurry from one end face of the carrier or sucking up the catalyst slurry. In this way, by forming a catalyst coat layer of catalyst slurry on the portion where the outflow side partition wall is disposed, and drying and firing the catalyst coat layer, the outflow side partition wall becomes relatively thick. The honeycomb catalyst body configured as described above can be easily manufactured. Examples of the catalyst component contained in the catalyst slurry include zeolite.

  Hereinafter, more specific examples of the above-described “(1) to (5) of the method of making the thickness smaller than the thickness of the outflow side partition wall” will be described.

(1) A method of reducing the thickness of the inflow side partition wall by grinding the surface of the partition wall where the inflow side partition wall is disposed with a grinding tool such as a file (hereinafter referred to as “method (1)”). is there). In the method (1), it is preferable to use a file whose width is narrower than one side of the opening of the cell. In the method (1), for example, a jig in which the above-mentioned “files” are arranged at intervals corresponding to the cell pitch of the honeycomb structure portion is manufactured, and a single row of cells or one cell is produced using the jig. For the compartment, a method of grinding at the same time can be mentioned.

(2) A method of reducing the thickness of the inflow side partition wall by applying a solution such as an acid to the partition wall where the inflow side partition wall is disposed and partially eroding the partition wall (hereinafter referred to as “(2) Sometimes referred to as " In the method (2), it is preferable to use hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or the like as the solution. Further, according to the method (2), the length of the portion where the thickness of the inflow-side partition wall is reduced can be adjusted by adjusting the depth immersed in the solution. Further, according to the method (2), the thickness (in other words, the thinness) of the inflow side partition wall can be adjusted by adjusting the time for dipping in the solution.

(3) A method of reducing the thickness of the inflow side partition wall (hereinafter referred to as “(3)”) by forming the honeycomb structure portion by a method such as extrusion, and then extending the portion where the inflow side partition wall is disposed. Sometimes called "method"). In the method (3), after extrusion of the honeycomb formed body and before drying, the one side of the honeycomb formed body and the center portion of the honeycomb formed body are gripped, and a tensile load is applied in the flow path direction. By applying statically, the partition of the one end surface part of a honeycomb molded object can be made thin. After the honeycomb formed body is dried, the end face of the dried honeycomb formed body is cut away, whereby the length of the portion where the partition wall thickness is reduced can be adjusted.

(4) A method in which the surface of the partition wall where the inflow side partition wall is disposed is sandblasted to reduce the thickness of the inflow side partition wall (hereinafter sometimes referred to as “method (4)”). Examples of the method (4) include a method of sandblasting using a polishing material mainly composed of alumina oxide and having a particle size of 4 to 250 μm after drying the honeycomb formed body. By projecting the abrasive at an angle with respect to the partition, the length of the portion where the thickness of the partition is reduced can be adjusted. Moreover, the length of the part which makes the thickness of a partition thin can also be adjusted by adjusting the particle size of abrasive | polishing material, and the time which sandblasting is performed.

(5) A method of increasing the thickness of the outflow side partition by disposing a film of the same material as or different from the partition wall on the surface of the partition where the outflow side partition is disposed (hereinafter referred to as “(5) Sometimes referred to as " As the method (5), for example, a conventionally known method for forming a ceramic film, such as a dipping method, is used to attach a ceramic slurry to the partition wall surface of the honeycomb structure, and then dry and fire. Can be mentioned. As a method of (5), a material gas containing raw material fine particles is supplied from the inflow side opening end side of the honeycomb structure portion, and the raw material fine particles are deposited on the surfaces of the partition walls forming the cells. It is also possible to suitably employ the method to do. As the raw material fine particles, a cordierite raw material or the like can be used. With the method (5), the thickness of the outflow side partition wall can be easily increased. The thickness of the outflow side partition wall can be determined by changing the supply flow rate of the source gas within a predetermined range. Specifically, at the initial stage of supply, the raw material fine particles reach the inside of the honeycomb structure portion by increasing the supply flow rate, and then the supply flow rate is decreased. Raw material fine particles are deposited on the inflow side opening end of the structure. By changing the supply flow rate in this way, the partition wall thickness at the inflow side opening end portion and the partition wall thickness at the outflow side opening end portion can be easily varied.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Example 1
80 parts by mass of silicon carbide powder and 20 parts by mass of Si powder were mixed to obtain a mixed powder. A binder, a pore former, and water were added to 100 parts by mass of the mixed powder to obtain a forming raw material.

  Next, the forming raw materials were kneaded and kneaded to prepare a columnar clay. Then, the obtained cylindrical clay was formed into a honeycomb shape using an extrusion molding machine to obtain a honeycomb formed body. The obtained honeycomb formed body was dielectrically heated and dried, and then dried at 120 ° C. for 2 hours using a hot air dryer to obtain a honeycomb dried body.

  A plugged portion was formed on the dried honeycomb formed body (honeycomb dried body). Specifically, first, a mask was applied to the opening of the cell on the inflow end face side of the honeycomb formed body. At this time, cells with masks and cells without masks were alternately arranged. Then, the end portion of the honeycomb formed body on the side where the mask was applied was immersed in the plugging slurry, and the opening portion of the cell where the mask was not applied was filled with the plugging slurry. Then, the plugged portions were formed in the same manner for the remaining cells on the outflow end surface of the honeycomb formed body after drying (that is, the cells in which the plugged portions were not formed on the inflow end surface).

  Next, the honeycomb formed body in which the plugged portions were formed was calcined (degreasing) at 550 ° C. for 3 hours in an air atmosphere. Thereafter, firing was performed at about 1450 ° C. for 2 hours in an Ar inert atmosphere to prepare a honeycomb structure precursor.

The resulting honeycomb structure precursor has a cylindrical shape with a length from the inflow end surface to the outflow end surface of 140.5 mm and a diameter of a cross section perpendicular to the direction extending from the inflow end surface to the outflow end surface of 165.0 mm. there were. The partition wall thickness of the honeycomb structure portion of the honeycomb structure precursor was 0.305 mm, and the cell density was 47 cells / cm ² . The porosity of the partition walls was 63%. The porosity of the partition wall is a value measured by “Autopore III 9420 (trade name)” manufactured by Micromeritics.

  Next, the surface of the partition wall of the obtained precursor of the honeycomb structure disposed in the range from the inflow end surface to 20% of the total length is ground with a file, and the partition wall disposed in the range Reduced the thickness. The thickness of the partition wall after grinding was 0.254 mm. Thus, the honeycomb structure of Example 1 was produced. The ground partition wall is the “inflow side partition wall” in the present invention.

Table 1 shows the “partition wall thickness A _out (mm)”, “inflow side partition wall thickness A _in (mm)”, “A _out −A _in (mm) _in the honeycomb structure of Example 1. ) ". Table 1 shows “the ratio of the applied length of the inflow side partition wall (%)”, “the total length L (mm) of the honeycomb structure”, and “the applied length L _in (mm) of the inflow side partition wall”. . “A _out −A _in (mm)” is a value (mm) obtained by subtracting “thickness A _in (mm) of the inflow side partition wall” from “thickness A _out (mm) of the partition wall at the outflow end face”. It is. “Ratio of application length of inflow side partition wall (%)” is the percentage of the length L _in from the inflow end face where the inflow side partition wall is disposed to the total length L of the honeycomb structure (L _in / L × 100 ). The “applicable length L _in (mm) of the inflow-side partition wall” is a length L _in (mm) from the inflow end surface on which the above-described inflow-side partition wall is disposed.

  About the obtained honeycomb structure, the reduction rate of pressure loss was calculated | required with the following method. Further, the obtained honeycomb structure was evaluated for a destructive test by the following method. The results are shown in Table 1.

[Pressure loss reduction rate (%)]
First, the pressure at the inflow end face side and the outflow end face side of the honeycomb structure when air at room temperature (25 ° C.) was passed through the honeycomb structure to be evaluated at a flow rate of 10 Nm ³ / min was measured. by calculating the to determine the pressure loss P _1. In addition, the pressure loss P ₀ was determined for the honeycomb structures of Comparative Examples 1 and 5 to 7 in the same manner. The honeycomb structures of Comparative Examples 1 and 5 to 7 are comparative honeycomb structures when the pressure loss reduction rate is obtained. From the pressure loss P ₀ of the honeycomb structure to be compared, a value obtained by subtracting the pressure loss P ₁ of the honeycomb structure being evaluated to determine the percentage of the value obtained by dividing the pressure loss P ₀ of the honeycomb structure to be compared . That is, the pressure loss reduction rate (%) was calculated by the following equation (1). In addition, in the honeycomb structures of Examples 1 to 3, 7 to 11 and Comparative Examples 2 to 4, the honeycomb structure of Comparative Example 1 is an evaluation target. In the honeycomb structure of Example 4, the honeycomb structure of Comparative Example 5 is an evaluation target. In the honeycomb structure of Example 5, the honeycomb structure of Comparative Example 6 is an evaluation target. In the honeycomb structure of Example 6, the honeycomb structure of Comparative Example 7 is an evaluation target. The pressure loss reduction rate (%) is determined to be acceptable when a pressure loss reduction of 5% or more is confirmed.
Reduction rate of pressure loss (%) = {(P ₀ −P ₁ ) / P ₀ × 100} (1)

[Evaluation of destructive testing]
First, a range of 130 mm from the outflow end face of the honeycomb structure was gripped by MAFTEC (trade name) manufactured by Mitsubishi Plastics. In this way, air heated by a propane burner was supplied to the honeycomb structure holding the outflow end face while applying vibration with a frequency of 100 Hz and an acceleration of 30 G, and the test was conducted for 100 hours (heating vibration (hot vibration) test). The conditions for flowing heated air in the heating vibration (hot vibration) test were a flow rate of 2 Nm ³ / min and a temperature of 150 to 800 ° C. (one cycle of 20 minutes). After the heating vibration test, whether or not the partition walls of the honeycomb structure were damaged was visually confirmed. The case where no damage was confirmed in the partition walls of the honeycomb structure was determined as “OK (passed)”. The case where damage was confirmed in the partition walls of the honeycomb structure was determined as “NG (failed)”.

(Examples 2-6, Comparative Examples 1-7)
“Thickness of partition wall A _out (mm) at the outflow end face”, “Thickness of inflow side partition wall A _in (mm)”, “Ratio of application length of inflow side partition wall (%)”, “ A honeycomb structure was manufactured in the same manner as in Example 1 except that the “full length L” was changed as shown in Table 1. In Comparative Examples 1 to 5-7, a honeycomb structure having a constant partition wall thickness was formed in the entire area from the inflow end surface to the outflow end surface of the honeycomb structure without grinding the partition walls. Produced.

  About the honeycomb structure of Examples 2-6 and Comparative Examples 2-4, the reduction rate (%) of the pressure loss was calculated | required by the method similar to Example 1. FIG. In addition, the honeycomb structures of Examples 2 to 6 and Comparative Examples 2 to 4 were evaluated for the destructive test in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
In Example 7, a honeycomb structure was manufactured by applying acid to the partition wall where the inflow side partition wall is disposed, partially eroding the partition wall, and reducing the thickness of the inflow side partition wall. . Except for the above-described method for reducing the thickness of the inflow-side partition wall, the method for manufacturing the precursor of the honeycomb structure is the same as that in Example 1. In the honeycomb structure of Example 7, “the partition wall thickness A _out (mm) at the outflow end face”, “the inflow side partition wall thickness A _in (mm)”, “A _out −A _in (mm)”, “ Table 1 shows the ratio of the applied length of the inflow side partition walls, the “total length L of the honeycomb structure”, and the “applied length L _in (mm) of the inflow side partition walls”.

(Example 8)
In Example 8, a honeycomb formed body was manufactured by extrusion molding, and then a portion where the inflow side partition wall was disposed was extended to reduce the thickness of the inflow side partition wall, thereby manufacturing a honeycomb structure. Except for the method of reducing the thickness of the inflow side partition wall described above, the method for manufacturing the honeycomb formed body and the precursor of the honeycomb structure is the same method as in Example 1. In the honeycomb structure of Example 8, “the partition wall thickness A _out (mm) at the outflow end face”, “the inflow side partition wall thickness A _in (mm)”, “A _out −A _in (mm)”, “ Table 1 shows the ratio of the applied length of the inflow side partition walls, the “total length L of the honeycomb structure”, and the “applied length L _in (mm) of the inflow side partition walls”.

Example 9
In Example 9, the honeycomb structure was manufactured by sandblasting the surface of the partition wall where the inflow side partition wall is disposed to reduce the thickness of the inflow side partition wall. Except for the above-described method for reducing the thickness of the inflow-side partition wall, the method for manufacturing the precursor of the honeycomb structure is the same as that in Example 1. In the honeycomb structure of Example 9, “partition wall thickness A _out (mm)”, “inflow side partition wall thickness A _in (mm)”, “A _out −A _in (mm)”, “ Table 1 shows the ratio of the applied length of the inflow side partition walls, the “total length L of the honeycomb structure”, and the “applied length L _in (mm) of the inflow side partition walls”.

(Examples 10 to 12)
In Examples 10 to 12, the honeycomb structure is obtained by disposing a ceramic film made of the same material as the partition wall on the surface of the partition wall where the outflow side partition wall is disposed, thereby increasing the thickness of the outflow side partition wall. Was made. That is, in Examples 10 to 12, honeycomb structures were manufactured by relatively reducing the thickness of the inflow side partition walls. The ceramic film was prepared by applying a ceramic slurry prepared from a cordierite raw material or the like to a portion where the outflow side partition wall is disposed. Except for the method of applying the ceramic slurry and increasing the thickness of the outflow side partition wall, the method for producing the honeycomb structure precursor is the same as that of Example 1. In the honeycomb structures of Examples 10 to 12, “thickness of partition wall A _out (mm)”, “thickness of partition wall A _in (mm)”, “A _out −A _in (mm)” Table 1 shows “the ratio of the applied length of the inflow side partition walls”, “the total length L of the honeycomb structure”, and “the applied length L _in (mm) of the inflow side partition walls”. In Examples 10 to 12, the supply ratio of the raw material fine particles serving as the raw material of the ceramic film was adjusted to adjust the “applied length ratio (%) of inflow side partition wall”.

(Examples 13 to 15)
In Examples 13 to 15, a honeycomb structure was produced by increasing the thickness of the outflow side partition by supporting the catalyst on the surface of the partition where the outflow side partition was disposed. That is, in Examples 13 to 15, honeycomb structures were manufactured by relatively reducing the thickness of the inflow side partition walls. The catalyst was supported by coating a catalyst slurry prepared from zeolite or the like on a portion where the outflow side partition wall was disposed. Except for the above-described method of supporting the catalyst and increasing the thickness of the outflow side partition wall, the method for manufacturing the precursor of the honeycomb structure is the same as in Example 1. In the honeycomb structures of Examples 13 to 15, “partition wall thickness A _out (mm)”, “inflow side partition wall thickness A _in (mm)”, “A _out −A _in (mm)”. Table 1 shows “the ratio of the applied length of the inflow side partition walls”, “the total length L of the honeycomb structure”, and “the applied length L _in (mm) of the inflow side partition walls”. In Examples 13 to 15, the application range of the catalyst slurry was adjusted to adjust the “applied length ratio (%) of inflow side partition wall”.

  For the honeycomb structures of Examples 7 to 15, the reduction rate (%) of the pressure loss was determined in the same manner as in Example 1. In addition, the honeycomb structures of Examples 7 to 15 were evaluated for destructive tests in the same manner as in Example 1. The results are shown in Table 1.

(result)
In the honeycomb structures of Examples 1 to 15, the pressure loss reduction rate (%) was 5% or more, and the pressure loss was sufficiently reduced. In addition, the honeycomb structures of Examples 1 to 15 were all evaluated as “OK” in the destructive test and excellent in durability. On the other hand, in the honeycomb structures of Comparative Examples 2 and 4, the pressure loss reduction rate (%) was 4%, and the pressure loss was not sufficiently reduced. The honeycomb structure of Comparative Example 3 was evaluated as “NG” in the destructive test, and the durability was low.

  The honeycomb structure of the present invention can be used as a catalyst carrier for supporting a catalyst for purifying exhaust gas. Moreover, the honeycomb structure of the present invention can be used for a filter for purifying exhaust gas.

1, 31: partition wall, 1a, 31a: partition wall (inflow side partition wall), 1b, 31b: partition wall (outflow side partition wall), 2, 32: cell, 3, 33: outer peripheral wall, 10, 40 honeycomb structure part, 11, 41: inflow end surface, 12, 42: outflow end surface, 45: partition wall substrate, 46: catalyst, 47: plugging portion, 100, 200, 300: honeycomb structure, A _in , B _in : partition wall thickness ( the thickness of the inflow-side partition _wall), a _{out, B} out: the thickness of the partition wall (the thickness of the outflow-side partition wall), L1, L2: entire length of the honeycomb structure _section, L1 _{in, L2} in: from the inflow end surface of the honeycomb structure section , L1 _out , L2 _out : Length from the outflow end face of the honeycomb structure part.

Claims (6)

A tubular honeycomb structure having partition walls that define a plurality of cells extending from an inflow end surface to an outflow end surface that serves as a fluid flow path,
The partition wall thickness A _{in in} the range from the inflow end surface of the honeycomb structure portion to at least 5% and 50% or less of the total length of the honeycomb structure portion is equal to the partition wall thickness at the outflow end surface of the honeycomb structure portion. A honeycomb structure which is thinner than the thickness A _out by 0.051 mm or more.   The honeycomb structure according to claim 1, wherein the partition wall is one in which a catalyst is supported on a partition wall base material made of a porous material.   The honeycomb structure according to claim 2, wherein the catalyst is supported on the partition wall base material at least in a range of more than 50% of the total length of the honeycomb structure portion.   Consists of the catalyst supported on the partition wall substrate in a range from 5% to 50% of the total length of the honeycomb structure portion from the inflow end surface and a range of more than 50% of the total length of the honeycomb structure portion. The honeycomb structure according to claim 2 or 3, wherein the thickness of the catalyst layer to be formed is different.   The thickness of the partition wall substrate in the range from 5% to 50% of the total length of the honeycomb structure portion from the inflow end surface is compared with the thickness of the partition wall substrate at the outflow end surface of the honeycomb structure portion. The honeycomb structure according to any one of claims 2 to 4, which is thinner by 0.051 mm or more.   The honeycomb structure according to any one of claims 1 to 5, wherein an overall length of the honeycomb structure part is 50 mm or more.

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