HONEYCOMB FILTER

Abstract

Honeycomb filter (100, 200), comprising: a columnar honeycomb structure (10) having arranged porous partition walls (1) surrounding a plurality of cells (2) serving as fluid passageways extending from an inflow end face (11) to an outflow end face (12); and porous sealing sections (5) provided either at the ends on the side of the inflow face (11) of the cells (2) or at the ends on the side of the outflow face (12) of the cells (2), wherein the sealing sections (5) include sealing sections (5) having cavities (6) therein, in the sealing sections (5) with the cavities (6), the porosity, including the cavities (6), extends as pores from 68% to 83%, wherein the sealing sections (5) with the cavities (6) are present only in a peripheral region (16) in a cross-section which is orthogonal to an extension direction of the cells (2) of the honeycomb structure (10), and the peripheral region (16) is a region extending to an eighth cell counted from a cell positioned at the outermost periphery of the honeycomb structure (10) in the cross section of the honeycomb structure (10) toward a center of the cross section.

Description

The present application is an application based on JP 2019-066,136, filed on 29.3.2019 in the Japanese Patent Office, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTIONField of the InventionThe present invention relates to a honeycomb filter. More particularly, the present invention relates to a honeycomb filter which can increase the exhaust gas purifying performance and effectively prevent the seal portions from falling off the cells when loaded with an exhaust gas purifying catalyst.DESCRIPTION OF THE RELATED ARTHeretofore, as a filter configured to trap particulate matter in exhaust gas discharged from an internal combustion engine such as a diesel engine or an apparatus configured to purify toxic gas components such as CO, HC and NOx, a honeycomb filter using a honeycomb structure has been known (see Patent Documents 1 to 4). The honeycomb structure has partition walls formed of a porous ceramic such as cordierite or silicon carbide, and includes a plurality of cells defined by the partition walls. In the honeycomb filter, the above honeycomb structure is provided with sealing portions that alternately seal the open ends on the inflow end face side of the plurality of cells and the open ends on the outflow end face side thereof. In other words, the honeycomb filter has a structure in which the inflow cells having the inflow end face side open and the outflow end face side sealed and the outflow cells having the inflow end face side sealed and the outflow end face side open are alternately arranged with the partition walls interposed therebetween. Further, in the honeycomb filter, the porous partition walls of the honeycomb structure function as filters that trap the particulates in an exhaust gas. Hereinafter, the particulate matter contained in an exhaust gas may be referred to as "PM". "PM" is an abbreviation for "particulate matter".In recent years, a honeycomb filter for purifying an exhaust gas discharged from an engine of an automobile or the like has been required to achieve a decrease in pressure loss mainly for improving the performance of fuel economy of automobiles. As one of the measures for reducing the pressure loss as compared with the conventional partition wall, investigations have been carried out on "thinner walls" to reduce the thickness of the partition walls of a honeycomb structure and "higher porosity" to further increase the porosity of the partition walls.Further prior art is also known from patent documents 5 and 6.[Patent Document 1] JP2015-047 554 A[Patent Document 2] WO 2011 / 036 971 A1[Patent Document 3] JP 2006-231 162 A[Patent Document 4] JP H07 42534 A[Patent Document 5] US 2006 / 0 185 335 A1[Patent Document 6] EP 2 481 542 A1Conventional honeycomb filters have presented a problem in that it is difficult to obtain satisfactory exhaust gas purifying performance when the honeycomb filters are loaded with an exhaust gas purifying catalyst. In recent years, for example, there has been a demand for improving the purification performance of honeycomb filters for purifying exhaust gases discharged from engines of automobiles to meet the exhaust regulations expanded each year due to the perception of environmental problems. In order to respond to the demand, for example, it has been necessary to promptly activate a catalyst loaded in a honeycomb filter by increasing the temperature rise speed of the catalyst. Consequently, there have been demands for developing a honeycomb filter that can provide satisfactory exhaust gas purifying performance immediately.Conventional honeycomb filters present a problem in that the seal portions are easily dropped from the ends of the cells. There has been another problem in that the seal portions are damaged due to various types of stresses applied to the honeycomb filters even if the seal portions do not fall off.For example, when a honeycomb filter is used as a filter for purifying an exhaust gas, the honeycomb filter is sometimes used by being accommodated in a shell body such as a metal shell. The accommodation of a honeycomb filter in a case body such as a metal case may be referred to as a mono-case. In the case of packaging a honeycomb filter, the honeycomb filter is held in a packaging body by applying a surface pressure to the circumferential surface of the honeycomb filter through the intermediary of a holding material such as a mat. Even if such a potting is carried out, the seal portions drop off from the ends of the cells or the seal portions are damaged in some cases. Specifically, the above holding material such as a mat is designed to be slightly shorter than the length in an axial direction of the honeycomb filter, and an edge of the holding material is sometimes disposed at a position from an end face of the honeycomb filter slightly toward the inner side. In such a case, sometimes in the cells positioned on the circumferential side of the honeycomb filter, the edge of the holding material is positioned unfavorably at the boundary between the sealing portions and the cavity portions of the cells, causing the sealing portions to easily fall off due to a high stress applied to the vicinity of the boundary from the holding material.SUMMARY OF THE INVENTIONThe present invention has been made in view of the above-described problems of the prior art. The present invention provides a honeycomb filter which, when loaded with an exhaust gas purifying catalyst, can increase the exhaust gas purifying performance and effectively prevent the sealing portions from falling off the cells.According to the present invention, a honeycomb filter described below is provided.[1] A honeycomb filter comprising:a pillar-shaped honeycomb structure having porous partition walls provided surrounding a plurality of cells serving as fluid passage passages extending from an inflow end face to an outflow end face; andporous sealing portions provided either at the ends on the inflow end face side of the cells or at the ends on the outflow end face side of the cells,wherein the sealing portions include sealing portions having voids therein, andin the seal portions having the voids, the porosity including the voids as pores extends from 68% to 83%,wherein the sealing portions having the voids are provided only in a circumferential region in a cross section orthogonal to an extending direction of the cells of the honeycomb structure, andthe circumferential region is a region extending up to an eighth cell counted from a cell positioned at the outermost circumference of the honeycomb structure in the cross section of the honeycomb structure toward a center of the cross section.[2] The honeycomb filter described in the above [1], wherein each of the sealing portions having the voids includes at least one void whose inner diameter extends in a radial direction of an end face of the honeycomb filter from 0.3 mm to 1.1 mm and whose inner diameter extends in the extending direction of the cells from 1.0 mm to 4.0 mm.[3] The honeycomb filter described in any one of the above [1] or [2], wherein the porosity of the partition walls extends from 50% to 70%.The honeycomb filter according to the present invention provides an effect that, when loaded with an exhaust gas purifying catalyst, enables the exhaust gas purifying performance to be increased, has high erosion resistance, and effectively prevents the sealing portions from falling off the cells. More specifically, the honeycomb filter provided with the sealing portions having the voids therein has an increased porosity of the sealing portions, and by reducing the stress concentration applied to the boundary region between the honeycomb structure and the sealing portions at the time of packaging, minimizes the possibility that the sealing portions fall off the cells. Further, the presence of the voids within the sealing portions suppresses an increase in mass of the honeycomb filter, increasing the temperature-rising performance of the honeycomb filter, thus enabling the exhaust gas purification catalyst to be promptly activated.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a perspective view schematically showing an embodiment of a honeycomb filter according to the present invention; FIG. 2 is a plan view showing the inflow end face side of the honeycomb filter shown in FIG. 1 ; FIG. 3 is a plan view showing the outflow end face side of the honeycomb filter shown in FIG. 1 ; FIG. 4 is a sectional view schematically showing the cross section taken along A-A' of FIG. 2; and FIG. 5 is a sectional view schematically showing a part of a cross section parallel to the extending direction of the cells of another embodiment of the honeycomb filter according to the present invention.DESCRIPTION OF THE PREFERRED EMBODIMENTSHereinafter, the embodiments of the present invention will be described; however, the present invention is not limited to the following embodiments. It should therefore be appreciated that those optionally produced by adding modifications, improvements, and the like to the following embodiments based on the general knowledge of a person skilled in the art without departing from the spirit of the present invention are also covered by the scope of the present invention.(1) Honeycomb FilterAn embodiment of the honeycomb filter according to the present invention is a honeycomb filter 100 shown in Figs. 1 to 4. FIG. 1 is a perspective view schematically showing the embodiment of the honeycomb filter according to the present invention. FIG. 2 is a plan view of the inflow end face side of the honeycomb filter shown in FIG. 1. FIG. 3 is a plan view of the outflow end face side of the honeycomb filter shown in FIG. 1. FIG. 4 is a sectional view schematically showing a cross section taken along A-A' of FIG. 2.As shown in FIGS. 1 to 4, the honeycomb filter 100 includes a honeycomb structure 10 and the sealing portions 5. the honeycomb structure 10 has the arranged porous partition walls 1 surrounding a plurality of cells 2 serving as fluid passage passages extending from an inflow end face 11 to an outflow end face 12. The honeycomb structure 10 is a columnar structure having the inflow end face 11 and the outflow end face 12 as their both end faces. In the honeycomb filter 100 of the present embodiment, the honeycomb structure 10 further includes a provided circumferential wall 3 enclosing the partition walls 1 on the circumferential side surface thereof.The seal portions 5 are provided either at the ends on the inflow end face 11 side of the cells 2 or at the ends on the outflow end face 12 side of the cells 2 to seal the open ends of the cells 2. The seal portions 5 are porous substances (i.e., porous bodies) made of a porous material. In the honeycomb filter 100 shown in FIGS. 1 to 4, the predetermined cells 2 having the seal portions 5 provided at the ends on the inflow end face 11 side and the remaining cells 2 having the seal portions 5 provided at the ends on the outflow end face 12 side are alternately arranged with the partition walls 1 interposed therebetween. In the following description, the cells 2 having the seal portions 5 provided at the ends on the inflow end face 11 side may be referred to as "the outflow cells 2 b". The cells 2 having the seal portions 5 provided at the ends on the outflow end face 12 side may be referred to as "the inflow cells 2 a".The honeycomb filter 100 includes, as the sealing portions 5, the sealing portions having the voids 6 therein. More specifically, at least one sealing portion 5 among the sealing portions 5 has a cavity 6 therein. Further, in the sealing portion 5, the porosity including the cavity 6 extends as a pore of 68% to 83%. The term "the porosity including the void 6 as a pore" means the porosity measured by regarding the void 6 as part of the pores of a porous body. The honeycomb filter 100 configured as described above provides an effect that, when loaded with an exhaust gas purifying catalyst, enables the exhaust gas purifying performance to be increased, has high erosion resistance, and effectively prevents the sealing portions 5 from falling off the cells 2. The honeycomb filter 100 is particularly effective as the honeycomb filter 100 provided with a honeycomb structure 10 having higher porosity. The provision of the sealing portions 5 having the voids 6 therein improves the porosity of the sealing portions 5 and reduces the stress concentration applied to the boundary portion between the honeycomb structure 10 and the sealing portions 5 at the time of canning, thus minimizing the possibility that the sealing portions 5 fall off the cells 2. In addition, the sealing portion 5 having the voids 6 therein suppresses an increase in mass of the honeycomb filter 100 while increasing the temperature-increasing performance of the honeycomb filter 100, thus enabling an exhaust gas purification catalyst to be promptly activated.The term "having the voids 6 therein" means that the voids 6, each of which has a maximum diameter of 0.1 mm or more in a direction in which the sealing portion 5 formed of a porous body is present. The maximum diameter of the cavity 6 in one direction can be determined from an image obtained by imaging the entire area of the cross-sectional layer of the cross section of the honeycomb filter 100 using, for example, industrial X-ray CT scanning.In the sealing portion 5 having the cavity 6, the porosity including the cavity 6 extends as a pore from 68% to 83%, preferably from 70% to 83%, and more preferably from 75% to 83%. In order to reduce the stress concentration applied to the boundary portion between the honeycomb structure 10 and the sealing portion 5 at the time of packaging, the above porosity preferably extends from 68% to 83%. Regarding the falling of the seal portions 5 that may occur at the time of enclosing, it is not preferable that the porosity of the seal portions 5 having the voids 6 be below 68%, for example. In terms of thermal shock resistance and wear or scraping (erosion) of the seal portions 5 or the like due to foreign matter coming together with exhaust gas flow, it is not preferable that the porosity of the seal portions 5 having the voids 6 exceeds 83%.The porosity of the sealing portions 5 having the voids 6 can be measured as described below. From the honeycomb filter 100, a cell equivalent portion including a sealing portion 5 and the partition walls 1 around the sealing portion 5 is cut out and processed to remove the partition walls 1 around the sealing portion 5. Thereafter, the mass of the sealing portion 5 is measured, and the porosity is calculated based on the measured mass and the true density of a sealing material constituting the sealing portion 5. When the porosity of the plugging portions 5 is measured, the porosity of all the plugging portions 5 provided at the ends of the cells 2 of the honeycomb structure 10 is to be measured.In the honeycomb filter 100, the sealing portions 5 may be mixed with the voids 6 and the sealing portions 5 may be mixed without the voids 6. The ratio of the seal portions 5 having the voids 6 with respect to the total number of the seal portions 5 is preferably 50% or more, more preferably extends from 50% to 70%, further more preferably extends from 60% to 70%, and particularly preferably extends from 65% to 70%.There is no particular limitation on the porosity of the sealing portions 5 without the voids 6. the porosity of the sealing portions 5 without the voids 6 extends, for example, preferably from 50% to 80%, more preferably from 60% to 80%, and particularly preferably extends from 65% to 75%. The porosity of the seal portions 5 without the voids 6 preferably remains in the above numerical ranges in terms of thermal shock resistance and resistance to abrasion or scraping (erosion) due to foreign matter coming together with exhaust gas flow. The porosity of the sealing portions 5 without the voids 6 can be measured according to the same method as that used for measuring the porosity of the above sealing portions 5 with the voids 6.There is no particular limitation to the sealing length of the sealing portions 5 in the extending direction of the cells 2. the sealing length of the sealing portions 5 preferably extends from 3 mm to 9 mm, more preferably extends from 3 mm to 8 mm, and particularly preferably extends from 3 mm to 7 mm, for example. It is not preferable that the sealing length of the sealing portions 5 be less than 3 mm due to the larger tendency that the sealing portions 5 fall too easily or that the erosion resistance deteriorates when the inflow end face 11 of the honeycomb filter 100 is dent or chiped. It is also not preferable that the sealing length of the sealing portions 5 exceeds 9 mm because an area through which a gas passes decreases, resulting in an increase in pressure loss or deterioration in exhaust gas purification performance.Each sealing length of the sealing portions 5 can be measured as described below. A rod having a length which is known and which is larger than the total length of the honeycomb filter 100 is inserted into each of the cells 2, and the seal length is measured from the difference between the length of a portion of the rod exposed from the honeycomb filter 100 and the length of the rod itself. When measuring each sealing length of the sealing portions 5, the sealing lengths of all the sealing portions 5 provided at the ends of the cells 2 of the honeycomb structure 10 are to be measured.The honeycomb filter 100 has a plurality of sealing portions 5 arranged from the periphery in the radial direction of the cross section of the honeycomb structure 10 toward the center. In the honeycomb filter 100, the sealing portions 5 having the voids 6 are randomly present in the radial direction of the cross section of the honeycomb structure 10. In other words, the sealing portions 5 having the voids 6 and the sealing portions 5 without the voids 6 are provided in a honeycomb filter 100 in a random manner. All the seal portions 5 in the honeycomb filter 100 may be the seal portions 5 having the voids 6. Alternatively, the sealing portions 5 having the cavities 6 may be provided only in a certain area (area). As in a honeycomb filter 200 shown in FIG. 5, the sealing portions 5 having the voids 6 may be present, for example, only in a circumferential region 16 in the cross section orthogonal to the extending direction of the cells 2 of the honeycomb structure 10. FIG. 5 is a sectional view schematically showing a part of the cross section parallel to the extending direction of the cells of another embodiment of the honeycomb filter according to the present invention. In the honeycomb filter 200 shown in FIG. 5, the same constituent elements as those of the honeycomb filter 100 shown in FIGS. 1 to 4 are assigned the same reference numerals, and their detailed descriptions are omitted.In the honeycomb filter 200 shown in FIG. 5, the sealing portions 5 having the voids 6 are provided only in a circumferential region 16 of a honeycomb structure 10. This configuration is preferable because the difference in elastic modulus between the sealing portions 5 in the circumferential region 16 and the honeycomb structure 10 increases, thus more effectively preventing the sealing portions 5 from falling off in the circumferential region 16. In addition, the above configuration is also preferable in terms of an increased exhaust gas purification performance due to an improvement in the heating performance and in terms of the erosion resistance of the honeycomb filter 200.The circumferential region 16 refers to a region extending up to the eighth cells 2 counted from the cells 2 positioned at the outermost circumference of the honeycomb structure 10 toward the center of the preceding cross section of the honeycomb structure 10. Further, the area expanding on the central side of the foregoing cross section among the cells 2 positioned closer to the center and directly to the eighth cells 2 (i.e., the ninth cells 2) counted from the cells 2 positioned at the outermost circumference is defined as a center area 15. From the viewpoint of thermal shock resistance and wear or scraping (erosion) of the seal portions 5 or the like caused by foreign materials coming together with exhaust gas flow, the seal portions 5 having the voids 6 are preferably not present in the center region 15 and present only in the peripheral region 16.When the seal portions 5 having the voids 6 are present only in the circumferential region 16 of the honeycomb structure 10, all the seal portions 5 present in the circumferential region 16 are preferably the seal portions 5 having the voids 6, however, alternatively, the seal portions 5 having the voids 6 and the seal portions 5 without the voids 6 in the circumferential region 16 may be mixed.The sealing portion 5 in the honeycomb filter 100 shown in FIGS. 1 to 4 preferably has at least one cavity 6, the inner diameter of which in the radial direction of an end face of the honeycomb filter 100 extends from 0.3 mm to 1.1 mm, and the inner diameter of which in the extending direction of the cells 2 extends from 1.0 mm to 4.0 mm. Hereinafter, the inner diameter of the cavity 6 in the radial direction of the end surface of the honeycomb filter 100 may be simply referred to as "the inner diameter in the radial direction". Further, the inner diameter of the cavity 6 in the extending direction of the cells 2 may be referred to as "the inner diameter in the direction of the total length". The sealing portions 5 having the cavities 6 whose inner diameter in the radial direction extends from 0.3 mm to 1.1 mm and whose inner diameter in the direction of the entire length extends from 1.0 mm to 4.0 mm provide an effect of reducing the stress concentration exerted on the boundary portion between the honeycomb structure 10 and the sealing portions 5 at the time of canning. The inner diameters of the cavities 6 can be measured according to the method described below. The entire area of the cross-sectional layer of the cross section of the honeycomb filter 100 is imaged using an industrial X-ray CT scan, and the inner diameters of the voids 6 are measured from the obtained image. The cross section to be imaged of the honeycomb filter 100 may be a cross section parallel to the extending direction of the cells 2 of the honeycomb filter 100, or a cross section parallel to each end face (an inflow end face 11 or an outflow end face 12) of the honeycomb filter 100.In the honeycomb structure 10, the porosity of the partition walls 1 preferably extends from 50% to 70%, and more preferably from 55% to 63%. The honeycomb filter 100 exhibits another marked effect when the honeycomb structure 10 having high porosity is used, wherein the porosity of the partition walls 1 extends from 55% to 63%. The porosity of the partition walls 1 is referred to by a value measured by the mercury pressing method. The porosity of the partition walls 1 can be measured using, for example, AutoPore 9500 (trade name) by Micromeritics. A part of the partition walls 1 is cut out from the honeycomb structure 10 to obtain a test piece, and the measurement of the porosity of the partition walls 1 can be carried out using the test piece obtained as described above. The porosity of the partition walls 1 preferably takes a constant value throughout the honeycomb structure 10. The absolute value of the difference between a maximum value and a minimum value of the porosity of the partition walls 1 of each part is, for example, preferably 10% or less.In the honeycomb structure 10, the thickness of the partition walls 1 preferably extends from 0.15 mm to 0.30 mm, and more preferably from 0.15 mm to 0.25 mm, and particularly preferably from 0.20 mm to 0.25 mm. The thickness of the partition walls 1 can be measured using, for example, a scanning electron microscope or a microscope. If the thickness of the partition walls 1 is below 0.15 mm, sufficient strength cannot be obtained. On the other hand, when the thickness of the partition walls 1 exceeds 0.30 mm, the pressure loss of the honeycomb filter 100 may increase.There is no particular limitation on the shapes of the cells 2 defined by the partition walls 1. The shapes of the cells 2 in the cross section orthogonal to the extending direction of the cells 2 may be, for example, polygonal, circular, elliptic, or the like. A polygonal shape may be triangular, quadrangular, pentagonal, hexagonal, octagonal, or the like. The shapes of the cells 2 are preferably triangular, quadrangular, pentagonal, hexagonal or octagonal. Regarding the shapes of the cells 2, all the cells 2 may have the same shape or different shapes. For example, quadrangular cells and octagonal cells may be mixed, although not shown. Further, as for the sizes of the cells 2, all the cells 2 may have the same size or different sizes. Among the plurality of cells, for example, some cells may be larger and some other cells may be relatively smaller, although not shown. In the present invention, the term "cells" means the spaces surrounded by the partition walls.In the honeycomb structure 10, the cell density of the cells 2 defined by the partition walls 1 preferably extends from 27 to 51 cells / cm 2 and more preferably from 31 to 47 cells / cm 2. This configuration makes it possible to suppress an increase in pressure loss while maintaining the PM trapping performance of the honeycomb filter 100.The circumferential wall 3 of the honeycomb structure 10 may be configured integrally with the partition walls 1, or may be made of a circumferential coating layer formed by applying a circumferential coating material enclosing the partition walls 1. The circumferential coating layer may be provided on the circumferential side of the partition walls after the partition walls and the circumferential wall are integrally formed, and then the formed circumferential wall is removed by a publicly known method such as grinding in a manufacturing process, although not shown.The honeycomb structure 10 may be pillar-shaped, and the shapes of the inflow end face 11 and the outflow end face 12 may be circular, elliptical, polygonal, or the like.There is no particular limitation on the size of the honeycomb structure 10, for example, the length from the inflow end face 11 to the outflow end face 12 and the size of the cross section orthogonal to the extending direction of the cells 2 of the honeycomb structure 10. Each size may be appropriately selected so that an optimum purification performance is obtained when the honeycomb filter 100 is used as a filter for purifying an exhaust gas. The length from the inflow end face 11 to the outflow end face 12 of the honeycomb structure 10 preferably extends from 90 mm to 160 mm, for example, and more preferably extends from 120 mm to 140 mm. Further, the area of the cross section orthogonal to the extending direction of the cells 2 of the honeycomb structure 10 preferably extends from 100 cm 2 to 180 cm 2 and more preferably from 110 cm 2 and 150 cm 2.The material of the partition walls 1 preferably includes, for example, at least one material selected from a group including silicon carbide, cordierite, a silicon-silicon carbide composite material, a cordierite-silicon carbide composite material, silicon nitride, mullite, alumina, and aluminum titanate.There is also no particular limitation on the material of the seal portions 5, for example, the same material as the above-described material of the partition walls 1 may be used.(2) Manufacturing Method of Honeycomb FilterThere is no particular limitation on the method for manufacturing the honeycomb filter according to the present invention, and for example, the following method may be used. First, a plastic kneaded material for manufacturing the honeycomb structure is prepared. The kneaded material for manufacturing the honeycomb structure can be prepared by adding an additive such as a binder, a pore former, and optionally water to a material selected from the above suitable materials of the partition walls as raw material powders.Subsequently, the kneaded material obtained as described above is subjected to extrusion, to thereby obtain a pillar-shaped honeycomb formed body having the partition walls defining a plurality of cells and a provided circumferential wall surrounding the partition walls. Then, the obtained honeycomb formed article is dried by, for example, microwave and hot air.Subsequently, sealing portions are disposed at the open ends of the cells of the dried honeycomb formed body. More specifically, for example, first, a sealing material containing a raw material for forming the sealing portions is prepared. Then, a mask is provided on the inflow end face of the honeycomb formed body to cover the inflow cells. Next, the sealing material that has been prepared is filled in the open ends of the outflow cells that are not provided with the mask on the inflow end face side of the honeycomb formed body. Thereafter, the sealing material for the outflow end face of the honeycomb formed body is also filled in the open ends of the inflow cells by the same method described above.In manufacturing the honeycomb filter according to the present invention, desired voids can be selectively formed in the sealing portions by, for example, reducing the viscosity of a sealing material when the sealing material is filled.Then, the honeycomb formed body is fired with the sealing portions provided at the open ends of one side of the cells to produce the honeycomb filter according to the present invention. The firing temperature and the firing atmosphere vary according to a material, and a skilled artisan can select a firing temperature and a firing atmosphere that are most suitable for a selected material.(Examples)The following describes the present invention further specifically by Examples; however, the present invention is by no means limited by the Examples.(Example 1)Ten parts by mass of a pore former, 20 parts by mass of a dispersing medium, and 1 part by mass of an organic binder were added to 100 parts by mass of a cordierite forming raw material and mixed, thereby kneading the mixture to produce a kneaded material. As the starting material forming cordierite, alumina, aluminum hydroxide, kaolin, talc and silica were used. As the dispersing medium, water was used. As the organic binder, methyl cellulose was used. As the dispersant, dextrin was used. As the pore former, coke having an average particle diameter of 15 μm was used.Subsequently, the kneaded material was subjected to extrusion using an extruding die for producing honeycomb formed bodies, thereby obtaining a honeycomb formed body whose entire shape was a round pillar shape. The shape of the cells of the honeycomb formed body was quadrangular.Subsequently, the honeycomb formed body was dried by a microwave dryer and further dried by a hot air dryer to completely dry the honeycomb formed body. Thereafter, both end faces of the honeycomb formed body were cut to predetermined dimensions.Subsequently, a sealing material for forming the sealing portions was prepared. Thereafter, using the sealing material, the sealing portions were formed at the open ends of the cells on the inflow end face side of the dried honeycomb formed body. More specifically, a mask was first provided on the inflow end face of the honeycomb formed body to cover the inflow cells. Then, the open ends of the non-maskd outflow cells were filled with the sealing material having a lower viscosity, thereby forming the sealing portions.Subsequently, the outflow end face of the honeycomb formed body was further provided with a mask to cover the outflow cells. Then, the open ends of the inflow cells which were not provided with the mask were filled with the sealing material having a lower viscosity, thereby forming the sealing portions.Subsequently, the honeycomb formed body in which the seal portions were formed was degreased and fired, thereby producing the honeycomb filter of Example 1.The honeycomb filter of Example 1 was round in a pillar shape, and the shapes of its inflow end face and its outflow end face were circular. The diameters of the inflow end face and the outflow end face were 118 mm. Further, the length of the cells of the honeycomb filter in the extending direction was 127 mm. In the honeycomb filter of Example 1, the thickness of the partition walls was 0.22 mm, the porosity of the partition walls was 55%, and the cell density was 31 cells / cm 2. Table 1 shows the thickness of the partition walls, the porosity of the partition walls, and the cell density of the honeycomb filter. The porosity of the partition walls was measured using AutoPore 9500 (trade name) of Micromeritics.In the honeycomb filter of Example 1, the sealing length of the sealing portions was 5.0 mm. Further, in the cross section orthogonal to the extending direction of the cells of the honeycomb structure, the sealing portions provided in the entire area of the cross section had voids therein. The presence of the voids within the sealing portions was checked by imaging the entire area of the cross-sectional layer of the cross section of the honeycomb filter portion using industrial X-ray CT scanning. The presence of the voids within the sealing portions is shown in the "presence of voids" column of Table 1. The existence area of the seal portions having the cavities is shown in the column "existence area" of "seal portions having cavities" of Table 1. In the "existence area" of Table 1, "only in the circumferential area" means that the seal portions having the voids are present only in the circumferential area of the honeycomb structure. "Entire area" means that the seal portions having the voids are present over the entire area of the honeycomb structure.The inner diameters of each of the voids within the sealing portions were measured according to the following method. First, the entire area of the cross-sectional layer of the cross section of the honeycomb filter portion was imaged using industrial X-ray CT scanning. Then, the inner diameters of the voids within each sealing portion were measured from the obtained image. The average value of the inner diameters in the radial direction of the cavities and the average value of the inner diameters in the direction of the total length of the cavities were calculated. The inner diameter (the average value) in the radial direction of the cavities was 0.9 mm, while the inner diameter (the average value) in the direction of the total length of the cavities was 3 mm. The inner diameters of the cavities are shown in the columns of "inner diameter in the radial direction of the cavity (mm)" and "inner diameter in the direction of the total length of the cavity (mm)" in Table 1.The ratio of the number of the seal portions having the voids with respect to the total number of the seal portions is shown in the column "ratio to the total number (%)" of the "seal portions having voids" of Table 1. In the honeycomb filter of Example 1, all the seal portions have the voids, so that the above ratio is 100%.Further, the porosity of the seal portions having the voids was measured. The porosity of the seal portions having the voids was 72%. The results are shown in Table 1. When a honeycomb filter in Example 2 and after that, which will be discussed later, has the seal portions without the voids, the porosity of the seal portions without the voids was separately measured. The porosity of the seal portions having the voids is shown in the column "porosity (having voids) (%)", while the porosity of the seal portions having no voids is shown in the column "porosity (having no voids) (%)".In Examples 1 and 6 and Comparative Example 2, all the seal portions are the seal portions having the voids, so that the porosity of a surface excluding the voids in the seal portions having the voids was measured according to the following method. Specifically, first, from the measurement results of the foregoing industrial X-ray CT scan, the positions of the voids within the sealing portions having the voids were identified, and only a portion having no voids was cut from the sealing portion having the voids. Then, the porosity of the portion which was cut out was measured. For Examples 1 and 6 and Comparative Example 2, the "porosity of the portion without the voids of the sealing portion having the voids" measured as described above is exceptionally shown in the column "porosity (without voids) (%)" of Table 1. (Table 1) (Table 1)Example 10,225531yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes65Entire area0,9310072Example 20,225531yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes70Only Peripheral Area0,937074Example 30,225531yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes70Only Peripheral Area0,836573Example 40,225531yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes69Only Peripheral Area0,836072Example 50,226347yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes72Only Peripheral Area13,27080Example 60,226347yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes70Entire area0,6210073Example 70,226347yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes71Only Peripheral Area0,926575Example 80,226347yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes70Only Peripheral Area0,926074Example 90,246247yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes73Only Peripheral Area145581Example 100,195631yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes66Only Peripheral Area0,73,57069Comparative Example 10,246247No no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no no75-----Comparative Example 20,235431yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes yes65Entire area0,4310066Further, on the honeycomb filter of Example 1, "evaluation of exhaust gas purifying performance", "evaluation of erosion resistance", and "evaluation of falling of seal portions" were carried out according to the following method. Table 2 shows the results.[Evaluation of Exhaust Gas Purification Performance]First, exhaust gas purifiers were produced using the honeycomb filters of Examples as the filters for purifying an exhaust gas. Each of the manufactured exhaust gas purifiers was connected to an outlet side of an engine exhaust manifold of an automobile with a 1,2-I direct-injection gasoline engine, and the concentration of NOx contained in the gas discharged through the outlet port of the exhaust gas purifier was measured to determine the NOx purification rate. Based on the value of each measured NOx purification rate, the exhaust gas purification performance was evaluated according to the following evaluation standard. The column "NOx purification rate ratio (%)" of Table 2 shows the value of the NOx purification rate (%) of the exhaust gas purifier using the honeycomb filter of each example when the value of the NOx purification rate of the exhaust gas purifier using the honeycomb filter of Comparative Example 1 is defined as 100%.Evaluation "excellent": When the value of the ratio of the NOx purification rate is 110 % or more, the evaluation result is referred to as "excellent".Rating "good": If the value of the ratio of the NOx purification rate exceeds 107% and is below 110%, then the rating result is referred to as "good".Rating "acceptable": If the value of the ratio of the NOx purification rate exceeds 100% and is 107% or less, then the rating result is referred to as "acceptable".Evaluation "Failed": When the value of the ratio of the NOx purification rate is 100% or less, the evaluation result is referred to as "Failed".[Evaluation of Falling of Sealing Portions]The side surface of the honeycomb filter of each example was wound with a mat according to the following method, and the honeycomb filter wound with the mat was slid into a shell body to hold the honeycomb filter by the shell body. In the wrapping of the mat, an edge of the mat was positioned at 5 mm on the inner side of an end face of the honeycomb structure constituting the honeycomb filter, with the whole side face of the honeycomb filter being covered with the mat. The honeycomb filter was held so that the degree of compression, i.e., the effective bulk density in the gap [GBD] (GBD), of the mat at this time was 0.45 g / cm 3 and the occurrence of falling of the seal portions from the cells was checked.Evaluation "OK": When the "falling of the seal portions" does not occur in the honeycomb filter to be evaluated, the evaluation result is referred to as "OK".Evaluation "NG": When the "falling of the seal portions" occurs in the honeycomb filter to be evaluated, the evaluation result is referred to as "NG".[Evaluation of Erosion Resistance]First, a honeycomb filter was shot (accommodated) into a sleeve body, and the shot honeycomb filter was placed on a gas burner inspection apparatus. Then, SiC abrasive grain was collided with the inflow end face of the honeycomb filter by the gas burner inspection device. The conditions under which the abrasive grain collapsed were as follows. The amount of grain fed was 5 grams. The temperature of the gas introduced into the honeycomb filter was 700° C. The flow rate of the gas introduced into the honeycomb filter was 120 m / s. The test time was 10 minutes during which the abrasive grain was gradually introduced. Thereafter, the honeycomb filter was taken out, and the honeycomb filter which had been taken out was photographed by computed tomography (CT), whereby the abrasion depth in the honeycomb filter (an erosion depth (mm)) caused by the impact of the abrasive grain was calculated. In the measurement test of the erosion amount, an abrasive grain having an average particle diameter of 50 μm was used. The "erosion resistance" of the honeycomb filter was evaluated according to the following evaluation standards. For Examples 1 to 10, Comparative Example 1 was defined as the reference honeycomb filter. The "erosion depth ratio (%)" of Table 2 shows the ratios of the erosion depths of the honeycomb filters to be evaluated when the erosion depth of the reference honeycomb filter is defined as 100%.Rating "excellent": If the value of the ratio of the erosion depth is below 70%, then the rating result is referred to as "excellent".Evaluation "good": When the value of the ratio of the erosion depth is 70% or more and is below 80%, the evaluation result is referred to as "good".Evaluation "acceptable": When the value of the ratio of the erosion depth is 80% or more and is below 100%, the evaluation result is referred to as "acceptable".Evaluation "Failed": When the value of the ratio of the erosion depth is 100% or more, the evaluation result is referred to as "Failed".(Examples 2 to 10)The honeycomb filters were produced according to the same method as that used for the honeycomb filter of Example 1, except that the configurations of the sealing portions were changed as shown in Table 1. In the honeycomb filters of Examples 2 to 5 and 7 to 10, the sealing portions existing in the circumferential portion of the cross section orthogonal to the extending direction of the cells of the honeycomb structure had the voids therein. More specifically, in the above cross section of the honeycomb filter of each of Examples 2 to 5 and 7 to 10, the sealing portions existing in a region extending toward the eighth cells counted toward the center of the cross section from the cells positioned at the outermost periphery of the honeycomb structure had the voids therein. In Examples 2 to 5 and 7 to 10, the viscosity of the sealing material for forming the sealing portions in the peripheral portion and the central portion was changed, whereby the presence of the voids in the sealing portions was adjusted.(Comparative Examples 1 and 2)The honeycomb filters were produced according to the same method as that used for the honeycomb filter of Example 1, except that the configurations of the sealing portions were changed as shown in Table 1. In the honeycomb filter of Comparative Example 1, none of the sealing portions has the voids therein. In the honeycomb filter of Comparative Example 2, although the seal portions have the voids, the porosity thereof is 66%.In addition, in the honeycomb filters of Examples 2 to 10 and Comparative Examples 1 and 2, the "evaluation of exhaust gas purifying performance", the "evaluation of falling of the sealing portion", and the "evaluation of erosion resistance" were carried out according to the same method as that used for Example 1. Table 2 shows the results. (Table 2) (Table 2)Example 110681acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptableacceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptableOKExample 210971good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good 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good good good good good good good good goodOKExample 310971good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good 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acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptableOKExample 610987good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good good 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acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptableOKExample 711277excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent 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good good good good good good good good good good good good good good good good good good good good good good good good good good good good good goodOKExample 910188acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable 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acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptableacceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable 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acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable acceptable 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excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellent excellentNG(Results)In the results of the "evaluation of exhaust gas purification performance", the "evaluation of falling of the sealing portion", and the "evaluation of erosion resistance", the honeycomb filters of Examples 1 to 10 have been superior to those of the honeycomb filter of Comparative Example 1 which is the reference. Consequently, it was verified that the honeycomb filters of Examples 1 to 10 had high cleaning performance, prevented the sealing portions from falling off the cells, and had high erosion resistance, while maintaining the required isostatic strength, as compared with the conventional honeycomb filters.Industrial applicabilityThe honeycomb filter according to the present invention can be used as a filter for trapping particulate matter in an exhaust gas.Description of the Reference Numerals1: Partition wall; 2: cell; 2a: inflow cell; 2b: outflow cell; 3: circumferential wall; 5: sealing portion; 6: cavity; 10: honeycomb structure; 11: inflow end face; 12: outflow end face; 15: central portion; 16: circumferential portion; and 100, 200: honeycomb filter.

Claims

A honeycomb filter (100, 200) comprising: a pillar-shaped honeycomb structure (10) having porous partition walls (1) arranged surrounding a plurality of cells (2) serving as fluid passage channels extending from an inflow end face (11) to an outflow end face (12); and porous sealing portions (5) provided at either the ends on the inflow end face (11) side of the cells (2) or the ends on the outflow end face (12) side of the cells (2), wherein the sealing portions (5) include sealing portions (5) having voids (6) therein, in the sealing portions (5) having the voids (6), the porosity including the voids (6) extends as pores of 68% to 83%, wherein the sealing portions (5) having the voids (6) are present only in a peripheral region (16) in a cross section, which is orthogonal to an extending direction of the cells (2) of the honeycomb structure (10), and the circumferential region (16) is a region extending up to an eighth cell counted from a cell positioned at the outermost circumference of the honeycomb structure (10) in the cross section of the honeycomb structure (10) toward a center of the cross section.The honeycomb filter (100, 200) according to claim 1, wherein each of the sealing portions (5) having the voids (6) has at least one void (6) whose inner diameter extends in a radial direction of an end face of the honeycomb filter (100, 200) from 0.3 mm to 1.1 mm and whose inner diameter extends in the extending direction of the cells (2) from 1.0 mm to 4.0 mm.The honeycomb filter (100, 200) according to any one of claims 1 or 2, wherein the porosity of the partition walls (1) extends from 50% to 70%.

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