JP3935159B2 - Ceramic honeycomb filter - Google Patents

Description

  The present invention relates to a ceramic honeycomb filter for removing fine particles contained in exhaust gas of a diesel engine.

  In order to remove particulates discharged from diesel engines, a ceramic honeycomb filter for collecting particulates with a structure in which the partition of the ceramic honeycomb structure has a porous structure and allows exhaust gas containing particulates to pass through the partition is used. Is underway. FIG. 1 is a front view of this ceramic honeycomb filter, and FIG. 2 is a schematic cross-sectional schematic view of the main part showing an example of use of the ceramic honeycomb filter for capturing particulates in exhaust gas. Usually, the shape of the outer periphery of the end face of the ceramic honeycomb filter 11 is substantially circular, and has a plurality of flow paths 11c formed by the outer peripheral wall 11a and the partition walls 11b orthogonal to the inner peripheral side of the outer peripheral wall 11a. Both ends of the path 11c are alternately plugged with the inflow side plugging material 1a and the outflow side plugging material 1b. As shown in FIG. 1, the ceramic honeycomb filter 11 is crimped and held in a metal storage container 12 through a support member 14 and is sandwiched and stored in a through-hole direction through a support member 13. . Here, although the support member 14 is generally formed of a metal mesh or a ceramic mat, it is used in combination according to use conditions. Therefore, when the ceramic honeycomb filter 11 is used in a diesel engine, mechanical vibrations and impacts from the engine, road surface, and the like are applied to the ceramic honeycomb filter via the support members 13 and 14.

  The exhaust gas purification action of the ceramic honeycomb filter having such a structure is performed as follows. First, the inflow side exhaust gas 2a flows in from the flow path 11c opened in the end surface of the inflow side of the ceramic honeycomb filter 11 housed in the storage container 12, passes through the partition wall 11b as shown by the arrow, and flows into the outflow side exhaust gas. Exhaust as 2b. When the inflow side exhaust gas 2a passes through the partition wall 11b, the particulates contained in the inflow side exhaust gas 2a are captured by the partition wall 11b, and the purified exhaust gas is released into the atmosphere as the outflow side exhaust gas 2b. . When the amount of fine particles trapped in the partition wall 11b exceeds a certain amount, the filter is clogged. Therefore, the filter is regenerated by burning it with a burner or an electric heater.

  As described above, the ceramic honeycomb filter for removing particulates contained in the exhaust gas of a diesel engine is housed and supported in a metal container, and particulate collection and combustion are repeatedly performed on the filter. In addition, since the ceramic honeycomb filter is subjected to mechanical vibration and impact, it has high particulate collection efficiency, low pressure loss, withstands the supporting force of the support member, and mechanical impact. In addition to being strong enough to withstand heat shocks, it is required to satisfy many characteristics such as efficient regeneration of the filter by particulate combustion.

Among the necessary characteristics of this ceramic honeycomb filter, the pressure loss and the collection efficiency of fine particles and the strength are in a contradictory relationship. Patent Documents 1, 2, and 3 describe techniques for controlling the pore diameter, pore distribution, or the size of pores existing on the partition wall surface. In the invention described in Patent Document 1, pores having a pore diameter of 5 to 40 μm and large pores having a pore diameter of 40 to 100 μm are formed on the partition wall surface, and the number of the small holes is 5 to 40 times the number of the large holes. Furthermore, the filter has an average pore diameter larger than 15 μm and a cumulative pore volume of 0.3 to 0.7 cm ³ / g, so that the collection efficiency can be maintained at a high value from the beginning. In addition, the pressure loss is said to be kept low. In the invention described in Patent Document 2, the pore volume having a pore diameter of less than 10 μm is 15% or less of the total pore volume, and the pore volume having a pore diameter of 10 to 50 μm is 75% or more of the total pore volume, A porous honeycomb filter having a pore volume exceeding a pore diameter of 50 μm is 10% or less of the total pore volume, a filter that has a high particulate collection efficiency and can prevent an increase in pressure loss due to pore clogging. Is supposed to be obtained. Further, in the invention described in Patent Document 3, the pore volume in the range of 5 to 20 μm in pore diameter is in the range of 30 to 40% of the total pore volume, and the pore in the range of 20 to 200 μm in pore diameter. An exhaust gas purifying filter having a volume of 50 to 70% of the total pore volume can obtain a filter excellent in particulate collection efficiency and combustion characteristics.

Japanese Patent Publication No. 3-10365 JP 2002-219319 A Japanese Patent No. 3446558

  However, only the technology related to the ceramic honeycomb filter as disclosed in Patent Documents 1 to 3 as the prior art has the following problems, has a low pressure loss characteristic, and mechanical at the time of use. A ceramic honeycomb filter having a strength capable of withstanding vibration and impact could not be obtained.

In the filter described in Patent Document 1, the total pore volume is 0.3 to 0.7 cm ³ / g, as shown in FIG. Although the range of the cumulative pore volume that can be taken is specified for pores having a pore diameter of 1 to 100 μm, the pore volume of 100 μm or more is at most 0.01 cm ³ / g or less. . With respect to the pores having a pore diameter of 100 μm or more, the exhaust gas containing fine particles easily passes through the inside of the pores. Therefore, the presence of an appropriate amount in the partition wall can reduce the pressure loss of the filter. In the filter described in Patent Document 1, since the cumulative pore volume of pores exceeding 100 μm is 0.01 cm ³ / g or less, there is a problem that low pressure loss characteristics cannot be obtained. Further, as shown in FIG. 4, the pore volume of 1 to 100 μm is described as being able to take a wide range as shown in FIG. 4, but the detailed distribution of the pores of 1 to 100 μm is described. Since there is no provision for the filter, there is a problem that a filter having both low pressure loss characteristics and high strength cannot be obtained.

  In the filter described in Patent Document 2, the pore volume having a pore diameter of less than 10 μm is 15% or less of the total pore volume, and the pore volume having a pore diameter of 10 to 50 μm is 75% or more of the total pore volume. In addition, it is described that the pore volume exceeding the pore diameter of 50 μm is 10% or less of the total pore volume, but the pore diameter is 10 μm or less, the pore diameter is 10 to 50 μm, the pore diameter is 50 to 100 μm, Since no detailed distribution of pores having a pore diameter of 100 μm or more is taken into consideration, there has been a problem that a filter having both low pressure loss and high strength cannot be obtained.

  In the filter described in Patent Document 3, the pore volume within a pore diameter range of 5 to 20 μm is within a range of 30 to 40% of the total pore volume, and the pore diameter within a pore diameter range of 20 to 200 μm. Although it is described that the volume is 50 to 70% of the total pore volume, the detailed distribution of pores having a pore diameter of 5 to 20 μm and a pore diameter of 20 to 200 μm is not considered at all, Since there is no description of the porosity and the total pore volume, there is a problem that a filter having both low pressure loss and high strength cannot be obtained.

  An object of the present invention is to provide a ceramic honeycomb filter that solves the above-described problems, has a low pressure loss, and has a strength capable of withstanding a supporting force and mechanical shock by a supporting member.

The ceramic honeycomb filter of the present invention plugs the end of a predetermined flow path of the ceramic honeycomb structure, and allows the exhaust gas to pass through a porous partition wall that defines the flow path, whereby fine particles contained in the exhaust gas Honeycomb filter that removes the pores, the total pore volume of the porous partition wall is 0.57 to 0.80 cm ³ / g, and the pore volume of 100 μm or more is 0.02 to 0.08 cm ^3. / G.

In the ceramic honeycomb filter of the present invention, the pore distribution of the porous partition wall is such that the pore volume is 2 μm or more: 0.55 to 0.75 cm ³ / g, the pore volume is 5 μm or more: 0.54 to 0.00 . 74 cm ³ / g, pore volume of 10 μm or more: 0.45 to 0.65 cm ³ / g, pore volume of 20 μm or more: 0.25 to 0.45 cm ³ / g, pore volume of 40 μm or more : it is preferred that 0.07 ~ 0.20 cm ³ / g.

  In the ceramic honeycomb filter of the present invention, it is preferable that the flow path near the outer peripheral wall of the ceramic honeycomb filter is plugged at both ends.

  In the ceramic honeycomb filter of the present invention, the length from the filter end surface of the plugging material for plugging both ends of the flow path near the outer peripheral wall is not more than 8.2% of the total length of the ceramic honeycomb filter, and The flow path in which both ends are plugged preferably exists in a range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face.

  In the ceramic honeycomb filter of the present invention, the interval between the partition walls is 2.54 mm or less, and the outer end surface of at least a part of the plugging material plugging the channels of the ceramic honeycomb filter is the partition end surface. On the other hand, it is preferable that the protrusion protrudes 0.01 to 5 mm in the flow path direction, and the protruding portion has an inclined surface at least with respect to the flow path direction.

  Further, the ceramic honeycomb filter according to another aspect of the present invention plugs an end of a predetermined flow path of the ceramic honeycomb structure, and allows the exhaust gas to pass through a porous partition wall that defines the flow path. A ceramic honeycomb filter for removing fine particles contained therein, wherein an interval between partition walls is 2.54 mm or less, and an outer end surface of at least a part of the plugging material plugged is relative to an end surface of the partition wall. Projecting 0.01 to 5 mm in the flow path direction, the protruding portion has an inclined surface at least with respect to the flow path direction, and the flow path near the outer peripheral wall of the ceramic honeycomb filter is plugged at both ends. It is characterized by being.

  In the ceramic honeycomb filter of the present invention, the length from the filter end surface of the plugging material for plugging both ends of the flow path near the outer peripheral wall is not more than 8.2% of the total length of the ceramic honeycomb filter, and The flow path in which both ends are plugged preferably exists in a range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face.

Next, the effect in this invention is demonstrated.
The ceramic honeycomb filter of the present invention is contained in the exhaust gas by plugging the end of a predetermined flow path of the ceramic honeycomb structure and allowing the exhaust gas to pass through the porous partition walls defining the flow path. A ceramic honeycomb filter for removing fine particles, wherein a total pore volume of a porous partition wall is 0.57 to 0.80 cm ³ / g, and a pore volume of 100 μm or more is 0.02 to 0.08 cm ^3. / G. Thus, by setting the total pore volume to 0.57 to 0.80 cm ³ / g, the pressure loss of the honeycomb filter can be lowered, and pores having a size of 100 μm or more have a great influence on the pressure loss. By containing an appropriate amount of the volume of 0.02 to 0.08 cm ³ / g, the pressure loss can be further reduced without lowering the strength. Here, to limit the total pore volume in the range of 0.57 ~0.80cm ³ / g, when less than 0.57 ^cm 3 / g, the pressure loss since the absolute amount decreases the pores rises If it exceeds 0.80 cm ³ / g, the strength decreases. Further, the pore volume of 100 μm or more is limited to the range of 0.02 to 0.08 cm ³ / g. When the pore volume is less than 0.02 cm ³ / g, pores of 100 μm or more effective for reducing pressure loss are obtained. This is because the effect of reducing the pressure loss is not great, and when it exceeds 0.08 cm ³ / g, large pores of 100 μm or more increase. This is because the strength decreases.

Here, the pore distribution of the porous partition walls of the ceramic honeycomb filter is as follows: pore volume of 2 μm or more: 0.55 to 0.75 cm ³ / g, pore volume of 5 μm or more: 0.54 to 0.74 cm ³ / g, pore volume of 10 μm or more: 0.45 to 0.65 cm ³ / g, pore volume of 20 μm or more: 0.25 to 0.45 cm ³ / g, pore volume of 40 μm or more: The reason why it is preferable to be 0.07 to 0.20 cm ³ / g will be described below. By including a desired ratio of small pores of 2 μm or less to large pores of 100 μm or more in the porous partition walls, pores of various sizes communicate with each other and the communication ratio between the pores increases. This is because the low pressure loss characteristic can be obtained and the strength characteristic that can be practically used can be obtained.

Specifically, the more optimal range is that the total pore volume of the porous partition wall is 0.63 to 0.78 cm ³ / g, and the pore distribution is a pore volume of 2 μm or more: 0.58 to 0.73 cm ³ / g, 5 μm or more pore volume: 0.57 to 0.72 cm ³ / g, 10 μm or more pore volume: 0.48 to 0.63 cm ³ / g, 20 μm or more pore volume: 0.3~0.45cm ³ / g, 40μm or more pore volume: 0.10~0.20cm ³ / g, 100μm or more pore volume: a 0.02~0.07cm ³ / g. Thus, by adjusting the pore distribution to a more optimal range, the communication ratio of pores of various sizes is further improved, so that the pressure loss can be further reduced. The total pore volume and pore distribution can be measured by mercury porosimetry using, for example, Autopore III 9410 manufactured by Micromeritics.

  As described above, since the ceramic honeycomb filter of the present invention has its pore distribution adjusted to an appropriate range, the pressure loss is effectively reduced and the strength characteristics are secured. It is suitable for a ceramic honeycomb filter used in the exhaust gas purification apparatus.

Here, a preferable range of the pore distribution of the porous partition wall in the ceramic honeycomb filter of the present invention will be described with reference to FIG. FIG. 5 is a graph showing the relationship between the pore diameter and the cumulative pore volume. Point (52) indicates the upper limit of the total pore volume of the present invention, and point (51) indicates the total pore volume of the present invention. The lower limit of the volume is shown, the point ○ (54) indicates the upper limit of the cumulative pore volume of the present invention having a pore diameter of 100 μm or more, and the point ● (53) indicates the cumulative pore volume of the present invention having a pore diameter of 100 μm or more. A lower limit □ (56) indicates the upper limit of the preferred cumulative pore volume at a pore diameter of 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 40 μm or more of the present invention, and a point ■ (55) indicates the present invention. The lower limit of the preferable cumulative pore volume at a pore diameter of 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, or 40 μm or more is shown. Further, point (57) indicates the pore distribution of the porous partition walls of the ceramic honeycomb filter of Example 1 described in the best mode for carrying out the present invention. In the preferred ceramic honeycomb filter of the present invention, the cumulative pore volume with respect to each pore diameter is represented by points Δ (52), □ (56), and ◯ (54), and points ▲ (51), □ (55), and It suffices if it exists between points (53). As shown in FIG. 5, by keeping the cumulative pore volume for each pore diameter within a narrow range, both low pressure loss and high strength can be achieved.

  In the ceramic honeycomb filter of the present invention, the reason why the flow path in the vicinity of the outer peripheral wall is preferably plugged at both ends will be described with reference to the schematic diagrams of FIGS. FIG. 3 is a front view of a ceramic honeycomb filter according to a preferred embodiment of the present invention, and FIG. The ceramic honeycomb filter according to a preferred embodiment of the present invention has a plurality of flow paths 11c formed by an outer peripheral wall 11a and partition walls 11b that are substantially orthogonal to each other on the inner peripheral side of the outer peripheral wall. The inflow side plugging material 1a and the outflow side plugging material 1b are alternately plugged, and the flow path near the outer peripheral wall is plugged with the plugging material 1c at both ends. In the ceramic honeycomb filter of the present invention having such a structure, since both ends of the flow path in the vicinity of the outer peripheral wall are reinforced with the plugging material, the corners of the end face of the ceramic filter are less likely to be damaged. This is because the strength of the honeycomb structure is improved, and the honeycomb structure is less likely to be damaged by the support force of the support member, mechanical vibration or impact during use. Furthermore, the flow path in which both ends of the flow path near the outer peripheral wall are plugged acts as a heat insulating space, and the heat of combustion of the fine particles is generated from the inside of the filter through the outer peripheral wall during filter regeneration. This is because the temperature at the center of the filter is maintained at a high temperature and fine particles are burned well. Here, the flow path in the vicinity of the outer peripheral wall means a flow path group adjacent to the outer peripheral wall and a flow path group adjacent thereto as shown in FIGS. 3 and 4. Further, when the flow path near the outer peripheral wall is inclined with respect to the outer peripheral wall and does not reach both end faces of the honeycomb structure, one end is plugged with a plugging material on the end face, The other end may be plugged with an outer peripheral wall.

  In the ceramic honeycomb filter of the present invention, the length from the filter end surface of the plugging material plugging both ends of the flow path near the outer peripheral wall is not more than 8.2% of the total length of the ceramic honeycomb filter, and The flow path in which both ends are plugged is preferably present in a range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. By appropriately adjusting the existence range of the plugged portions where both ends in the vicinity of the outer peripheral wall are plugged, while maintaining the effect of improving the strength of the ceramic honeycomb filter due to low pressure loss and plugging at both ends, fine particle combustion This is because the filter can be regenerated satisfactorily.

  Here, the reason why the length from the end face of the plugging material plugging both ends of the flow path is preferably 8.2% or less of the total length of the filter is that the both ends of the flow path in the vicinity of the outer peripheral wall With this plugging material, while maintaining the effect of improving the strength of the ceramic honeycomb structure, the flow path functions effectively as a heat insulating space, and the diffusion of combustion heat to the metal container at the time of particulate combustion can be ignored This is because it becomes possible to hold it down. Here, if the length from the end face of the plugging material exceeds 8.2% of the total length of the filter, the diffusion of the combustion heat at the time of particulate combustion through the plugging material cannot be ignored, It is not preferable because the collected fine particles are likely to remain unburned and the filter regeneration rate may be lowered. Here, when the flow path in the vicinity of the outer peripheral wall is inclined with respect to the outer peripheral wall and does not reach both end faces of the honeycomb structure, one end is plugged with a plugging material on the end face. The other end portion is plugged with the outer peripheral wall. Therefore, the plugging material whose length from the end face of the plugging material is 8.2% or less of the total length of the filter is a honeycomb. It refers to a plugging material present on the end face of the structure.

  Further, the flow path whose both ends are plugged is a flow path that exists within a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. Is preferable because an increase in the pressure loss of the filter can be minimized. That is, plugging both ends of the flow path makes it difficult for exhaust gas to flow through the flow path, so the ratio of porous partition walls having a filter function is reduced, leading to an increase in pressure loss of the ceramic honeycomb filter. Although the adverse effect may occur, as shown in FIG. 2, both ends of the flow path near the outer peripheral wall may be blocked by the support members 13a and 13b, so both ends near the outer peripheral wall are plugged. This is because, by keeping the ratio of the flow paths within a certain range, the increase in the pressure loss of the filter can be minimized, and the engine performance is not deteriorated. On the other hand, when the flow path whose both ends are plugged exceeds the range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face, the filter is relatively Since the ratio of the partition wall having a function is reduced, the pressure loss of the filter is increased, so that the exhaust pressure of the engine is increased, and the engine performance may be deteriorated. Here, it is said that the flow path having both ends plugged exists in a range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. It means that the channel whose both ends are plugged on the end face of the filter exists in the channel corresponding to a position having a length five times as large as the partition wall pitch from the outer peripheral wall toward the center. That is, it is not necessary that all the flow paths corresponding to the position having a length five times the partition wall pitch are plugged at both ends, and the flow paths that are plugged at both ends depending on the part are the maximum. It exists in the range of 5 times the length of the partition wall pitch. Here, the flow path in which both ends are plugged exists from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face in a range of a maximum length of 5 × (partition wall pitch). This will be specifically described with reference to FIG. FIG. 3 shows that the flow path having both ends plugged exists in a range of 2 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. The imaginary line 15 shows an outline that is smaller by a length of 2 × (partition wall pitch) toward the center of the end face than the outer peripheral wall, and the flow path existing between the imaginary line 15 and the outer peripheral wall is at both ends. It is plugged with. FIG. 3 shows an example in which all the channels existing in the range of 2 × (partition wall pitch) length are plugged at both ends from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. However, the same effect can be obtained if 80% or more of these channels are plugged at both ends.

  Furthermore, in the ceramic honeycomb filter of the present invention, the length from the end face of the plugging material in which the flow path near the outer peripheral wall is plugged at both ends is 3.3% or less of the total length of the ceramic honeycomb filter. Thus, while maintaining the effect of improving the strength of the ceramic honeycomb structure by plugging both ends, the effect of the flow path near the outer peripheral wall acting as a heat insulating air layer is further increased, and the heat dissipation of the metal container from the outer peripheral wall of the filter is achieved. The collected particulate matter can be burned and removed efficiently, and the filter regeneration efficiency is further improved.

  Further, the flow path in the vicinity of the outer peripheral wall whose both ends are plugged is a flow path existing in a range of 3 × (partition wall pitch) at the maximum from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. As a result, the pressure loss of the filter can be further reduced while maintaining the effect of improving the strength of the ceramic honeycomb structure by plugging both ends and the excellent filter regeneration efficiency. Further improvement.

  In the ceramic honeycomb filter of the present invention, the interval between the partition walls is 2.54 mm or less, and the outer end face of at least a part of the plugging material plugging the flow path of the ceramic honeycomb filter is relative to the end face of the partition wall. The reason why it is preferable that the protrusion protrudes by 0.01 to 5 mm in the flow path direction and the protrusion has an inclined surface at least in the flow path direction will be described. A representative example of a preferred form of the plugged portion of the ceramic honeycomb filter of the present invention is shown in FIG. In the ceramic honeycomb filter of the present invention, the outer end surface 15 of the plugging material as shown in FIGS. 7 (a) and 7 (b) is flat due to the protruding portion having the inclined surface 1d in the flow path direction of the plugging material. Those formed so as to be in the same plane as the outer wall 16 of the partition wall, those having protrusions protruding by the film thickness as shown in FIG. 7C, or those shown in FIG. As shown, the outer end surface 15 of the plugging material is convex, and the outer end surface 15 of the plugging material is completely buried in the partition wall outer end surface 16 of the honeycomb structure to form a gap 18. Since the protruding portion of the plugging material protrudes with the inclined surface 1d as compared with the existing one, the substantial opening ratio on the exhaust gas inflow side of the flow path 11c is increased, and the exhaust gas flow is reduced. The resistance is reduced, and the exhaust gas flows smoothly in the direction of the flow path. Fine particles less likely deposited on the outer end face, because as a result, the effect is increased to prevent an increase in pressure loss due to flow path inlet constriction generated by the deposited particles.

  Here, the flow path near the outer peripheral wall may be blocked by contact with the support member 13a, and does not contribute to the purification of exhaust gas particulates. It does not have to protrude. As a protrusion part shape, it is a shape as shown in FIG. 8, for example. Moreover, even if the plugging material is present in a range that contributes to fine particle purification, it is not necessary for all the plugging materials to protrude and have inclined surfaces, and about 50% or more of the plugging materials protrude. If the inclined surface is provided, the effect of reducing an increase in pressure loss can be increased. Here, the protrusion length 23 is set to 0.01 to 5 mm. If the protrusion length is 0.01 mm or less, the inclined surface of the protrusion does not provide an effect of smoothly flowing the exhaust gas in the flow path direction. This is because fine particles may accumulate on the outer end surface of the sealing material, and the pressure loss may easily increase due to narrowing of the flow path entrance. On the other hand, if the protruding length exceeds 5 mm, when a mechanical load is applied to the outer end face of the plugging material, the bending stress acting near the end face of the partition wall of the plugging material increases. This is because the protruding portion may be damaged during handling such as insertion into the plug, resulting in a protruding length of the plugging material of less than 0.01 mm.

  Furthermore, when the projection length is 0.1 mm or more, the resistance of the plugging material with respect to the exhaust gas flow becomes smaller. Therefore, when the projection length is 2 mm or less, the projection portion of the plugging material is more damaged. Therefore, the protrusion length of 0.1 to 2 mm is a more preferable range.

  Moreover, it is more preferable that the angle with respect to the flow path direction of the inclined surface which the protrusion part with respect to the partition wall end surface of the plugging material has is 2 ° or more. The reason for this is that if the angle of the inclined surface with respect to the flow path direction is less than 2 °, the effect of flowing the exhaust gas smoothly in the flow path direction by the protruding portion is small, and it is formed at the outflow side end of the inclined surface of the protruding portion. This is because fine particles are likely to be deposited on the corner portion 25 (FIG. 6), and the deposition portion of the fine particles grows with this portion serving as a nucleus, which may cause an increase in pressure loss due to narrowing of the channel entrance. When the angle of the inclined surface of the protruding portion of the plugging member with respect to the partition wall surface with respect to the flow path direction is 80 ° or less, the resistance to the exhaust gas flow is reduced and the exhaust gas flows smoothly in the flow path direction. From the viewpoint of, it is more preferable.

  In the present invention, it is preferable that the outer end face of the plugging material is not buried in the end face of the partition wall. The reason for this is that even if the outer surface of the plugging material protrudes from the end face of the partition wall, if the gap 18 is formed as shown in FIG. This is because an increase in pressure loss is likely to occur due to narrowing of the flow path entrance.

  In the ceramic honeycomb filter of the present invention, the surface roughness (maximum height Ry) of the outer end face of the plugging material is preferably 200 μm or less. This is because if the maximum height Ry exceeds 200 μm, fine particles are likely to adhere and accumulate on the surface of the outer surface of the plugging material, and the pressure loss is likely to increase due to narrowing of the flow path entrance.

  The ceramic honeycomb filter of the present invention has been described mainly focusing on the shape of the plugging material at the exhaust gas inlet, but the shape of the plugging material on the end surface on the exhaust gas outlet side is not particularly limited, and the present invention The protrusions may be provided in the same manner as described above, or the partition wall end face and the plugging material end face may be formed in the same plane as in the prior art.

  A ceramic honeycomb filter according to another aspect of the present invention plugs a predetermined flow path end of a ceramic honeycomb structure, and allows the exhaust gas to pass through a porous partition wall that defines the flow path. A ceramic honeycomb filter for removing fine particles contained therein, wherein a partition gap is 2.54 mm or less, and an outer end surface of at least a part of the plugged material that is plugged flows with respect to a partition end surface. It protrudes 0.01 to 5 mm in the road direction, the protruding portion has an inclined surface at least with respect to the flow path direction, and the flow path near the outer peripheral wall of the ceramic honeycomb filter is plugged at both ends. Therefore, both low pressure loss characteristics and strength can be achieved. That is, in the ceramic honeycomb filter of the present invention, since the projecting portion of the plugging material projects with the inclined surface 1d, the substantial opening ratio on the exhaust gas inflow side of the flow path 11c increases, Since the resistance to gas flow is reduced and the exhaust gas flows smoothly in the direction of the flow path, it is difficult for fine particles to accumulate on the outer end face of the plugging material. The increase in loss can be prevented, and both ends of the flow path near the outer peripheral wall are reinforced with plugging material, so that the corners of the ceramic filter are less likely to be damaged. As a result, the ceramic honeycomb structure The strength is improved, and it is difficult to break due to mechanical vibration or impact during use, and both low pressure loss and strength can be achieved. Further, the flow path in which both ends of the flow path near the outer peripheral wall are plugged acts as a heat insulating space, and the heat of combustion of fine particles during the regeneration of the filter from the inside of the filter through the outer peripheral wall is a metal storage container. This is because the temperature at the center of the filter is maintained at a high temperature and fine particles are burned well. Here, the flow path in the vicinity of the outer peripheral wall means a flow path group adjacent to the outer peripheral wall and a flow path group adjacent thereto as shown in FIGS. 3 and 4. When the flow path near the outer peripheral wall is inclined with respect to the outer peripheral wall and does not reach both end faces of the honeycomb structure, one end is plugged with a plugging material at the end face, One end may be plugged with an outer peripheral wall.

  In the ceramic honeycomb filter of another invention of the present invention, the length from the filter end surface of the plugging material plugging both ends of the flow path near the outer peripheral wall is 8.2% or less of the total length of the ceramic honeycomb filter. In addition, the flow path in which both ends are plugged preferably exists in a range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. While maintaining the effect of improving the strength of the ceramic honeycomb filter due to low pressure loss and plugging at both ends, by appropriately adjusting the existence range of the plugged portions where both ends near the outer peripheral wall are plugged This is because the filter can be regenerated by burning fine particles.

  Here, the reason why the length from the end face of the plugging material plugging both ends of the flow path is preferably 8.2% or less of the total length of the filter is that the both ends of the flow path in the vicinity of the outer peripheral wall With this plugging material, while maintaining the effect of improving the strength of the ceramic honeycomb structure, the flow path functions effectively as a heat insulating space, and the diffusion of combustion heat to the metal container at the time of particulate combustion can be ignored This is because it becomes possible to hold it down. Here, if the length from the end face of the plugging material exceeds 8.2% of the total length of the filter, the diffusion of the combustion heat at the time of particulate combustion through the plugging material cannot be ignored, It is not preferable because the collected fine particles are likely to remain unburned and the filter regeneration rate may be lowered. Here, when the flow path in the vicinity of the outer peripheral wall is inclined with respect to the outer peripheral wall and does not reach both end faces of the honeycomb structure, one end is plugged with a plugging material on the end face. The other end portion is plugged with the outer peripheral wall. Therefore, the plugging material whose length from the end face of the plugging material is 8.2% or less of the total length of the filter is a honeycomb. It refers to a plugging material present on the end face of the structure.

  Further, the flow path whose both ends are plugged is a flow path that exists within a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face. Is preferable because an increase in the pressure loss of the filter can be minimized. That is, plugging both ends of the flow path makes it difficult for exhaust gas to flow through the flow path, so the ratio of porous partition walls having a filter function is reduced, leading to an increase in pressure loss of the ceramic honeycomb filter. Although the adverse effect may occur, as shown in FIG. 2, both ends of the flow path near the outer peripheral wall may be blocked by the support members 13a and 13b, so both ends near the outer peripheral wall are plugged. This is because, by keeping the ratio of the flow paths within a certain range, the increase in the pressure loss of the filter can be minimized, and the engine performance is not deteriorated. On the other hand, when the flow path whose both ends are plugged exceeds the range of a maximum length of 5 × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the center of the honeycomb filter end face, the filter is relatively Since the ratio of the partition wall having a function is reduced, the pressure loss of the filter is increased, so that the exhaust pressure of the engine is increased, and the engine performance may be deteriorated.

  Moreover, as a material which comprises the ceramic honeycomb filter of this invention, since this invention mainly targets the exhaust gas discharged | emitted from a diesel engine, it is preferable to use a material with good heat resistance. For this reason, it is preferable to use a ceramic material whose main crystal phase is cordierite, mullite, alumina, silicon nitride, silicon carbide, LAS, etc. Among them, ceramic honeycomb filters whose main crystal phase is cordierite are inexpensive and heat resistant. It is most preferable because it is excellent in chemical stability and chemically stable.

  The partition wall thickness of the ceramic honeycomb filter of the present invention is preferably 0.1 to 0.5 mm, and the partition wall pitch is preferably 1.3 mm or more. When the partition wall thickness is less than 0.1 mm, the strength of the partition walls is lowered particularly when a honeycomb filter having an outer diameter exceeding 150 mm is produced, which is not preferable. On the other hand, when the partition wall thickness exceeds 0.5 mm, the ventilation resistance of the partition wall to the exhaust gas of the honeycomb filter increases, and the pressure loss increases. A more preferable partition wall thickness is 0.2 to 0.4 mm. In addition, when the partition pitch is less than 1.3 mm, the opening area of the cell of the honeycomb filter becomes small, so that the pressure loss at the inlet of the honeycomb filter becomes large. An increase in the pressure loss of the honeycomb filter is not preferable because it leads to a reduction in engine output.

  In the present invention, it is more preferable that the outer peripheral wall of the ceramic honeycomb filter has a thickness of 0.3 to 2.0 mm and is composed of ceramic particles and an amorphous oxide matrix existing therebetween. . This is because the heat insulation effect of the flow path in the vicinity of the outer peripheral wall whose both end faces are plugged in the outer peripheral wall becomes more effective. Such an outer peripheral wall is obtained by removing the outer peripheral portion of the ceramic honeycomb structure by processing, and filling the outer peripheral surface having a concave groove extending in the axial direction with a coating material containing ceramic particles and a colloidal amorphous oxide. It can be formed by coating. Alternatively, the outer peripheral portion of the honeycomb structure formed body may be removed and then fired to fill and apply the coating material. During the removal process, the flow path and the outer peripheral wall may be inclined. In addition, the thickness of the outer peripheral wall is preferable from the viewpoint of heat insulation, but if it exceeds 2.0 mm, the outer wall tends to crack when a thermal shock is applied to the filter. If it is less than the range, the heat insulating effect cannot be obtained, so the range of 0.3 to 2 mm is preferable. Further, when the outer peripheral wall is composed of ceramic particles and an amorphous oxide matrix existing between them, the outer peripheral wall is formed in the outer peripheral wall as compared with the case where the outer peripheral wall is composed of a single ceramic. This is because the continuity of the ceramics is impaired, so that heat is hardly transmitted and the heat insulating effect on the outer peripheral wall is further improved. Here, as the ceramic particles, those having heat resistance such as cordierite, alumina, silica and mullite can be used, but cordierate particles and silica particles are particularly preferable because they have a small thermal expansion coefficient and are advantageous for thermal shock. . Furthermore, the size of the ceramic particles is preferably a powder having an average particle diameter of 50 μm or less because both heat insulation and strength can be achieved. In addition, the amorphous oxide matrix is used to bond ceramic particles to form a heat-resistant outer peripheral wall, but colloidal silica, colloidal alumina, water glass, etc. that become colloidal when forming the outer peripheral wall. Can be used. In addition to the amorphous oxide matrix formed from the ceramic particles and the colloidal material, ceramic fibers, alumina cement, etc. may be appropriately added to the outer peripheral wall as long as the heat resistance and strength are not impaired. good.

  As described above, according to the ceramic honeycomb filter of the present invention, since the distribution of pores formed in the porous partition walls of the ceramic honeycomb filter is optimized to a desired range, the pressure loss is low. Thus, it is possible to obtain a ceramic honeycomb filter having both the pressure loss and the strength, which has the strength to withstand the supporting force by the supporting member and mechanical vibration and impact. Furthermore, the flow path with both ends plugged with plugging material is provided in the vicinity of the outer peripheral wall of the filter, or the end face of the plugging material is projected, so that strength improvement and pressure loss reduction are ensured. It is possible to achieve a highly reliable ceramic honeycomb filter that achieves both pressure loss and strength. In addition, by providing a flow path in which both ends are plugged with plugging material in the vicinity of the outer peripheral wall of the filter, there is an effect that the fine particles can be burned efficiently and an increase in pressure loss due to unburned fine particles can be avoided. .

The ceramic honeycomb filter of the present invention can be manufactured, for example, as follows.
A cordierite-forming raw material powder such as kaolin, talc, silica, aluminum hydroxide, and alumina is prepared, and the chemical composition is in mass ratio, SiO ₂ : 48 to 52%, Al ₂ O ₃ : 33 to 37%, MgO: 12~15%, CaO: 0~0.05%, Na 2 O
_{: 0~0.05%, K 2 O:} 0~0.05%, TiO 2: 0~1.0%, Fe 2 O 3: 0~1.0%, PbO: 0~0.1%, P ₂ O ₅ : After adjusting to be 0 to 0.2%, the pore-forming material and the binder are added to the cordierite forming raw material powder and dry-mixed, and then water is added and then kneaded to improve the plasticity. Have the dredged soil. After this kneaded material is extruded by a known extrusion molding method, a molded body having a honeycomb structure is extruded, and then the molded body is dried by a known drying method such as microwave drying, dielectric drying, or hot air drying. Next, the dried honeycomb structure is placed in a firing furnace, fired at a temperature of 1350 to 1440 ° C., and the fine pores unique to cordierite ceramics in the partition walls and the traces after combustion removal of the pore former A ceramic honeycomb structure having formed pores is obtained.

Here, the total pore volume of the porous partition walls of the ceramic honeycomb structure made of a material having cordierite as the main crystal is 0.57 to 0.80 cm ³ / g, and the pore volume of 100 μm or more is 0.02 to 0. 0.08 cm ³ / g can be achieved by adjusting the particle size of the cordierite forming raw material to be used and the particle size of the pore former. Further, the pore distribution of the porous partition wall is set to a pore volume of 2 μm or more: 0.55 to 0.75 cm ³ / g, a pore volume of 5 μm or more: 0.54 to 0.74 cm ³ / g, 10 μm. more pore ^{volume: 0.45 ~ 0.65 cm 3 / g} , 20μm or more pore ^{volume: 0.25 ~ 0.45 cm 3 / g} , 40μm or more pore volume: from 0.07 to 0. 20 cm ³ / g can be achieved by adjusting the particle size of the cordierite forming raw material to be used and the particle size of the pore former. Here, among the cordierite forming raw materials, talc and silica have an average particle size of 10 to 30 μm, and the pore former has an average particle size of 10 μm or more, and the particle size of 10 to 100 μm accounts for 50% or more. It is effective to use at least things.

  The pore former is a known graphite, wheat flour, resin powder or the like, and is preferably adjusted so as to have a particle size distribution in which an average particle size of 10 μm or more and a particle size of 10 to 100 μm occupy 50% or more. Moreover, when using resin powder, it is good also as the particle size distribution which adjusts the manufacturing conditions and occupies 50% or more for the average particle diameter of 10 micrometers or more and 10-100 micrometers of particle diameters. In addition, if the pore former is substantially spherical, the pores formed in the partition walls also become substantially spherical, so that the stress concentration on the pores can be reduced, and the ceramic honeycomb having excellent mechanical strength It is preferable because a structure is obtained. Furthermore, if the pore former is hollow, it can be easily removed from the partition wall when the pore former is burned and removed, and the problem that the partition wall cracks during combustion removal is unlikely to occur. It is preferable because the yield is improved.

  FIG. 3 is a schematic view of the end face of the ceramic honeycomb filter according to the present invention. FIG. 4 is a schematic cross-sectional view of the ceramic honeycomb filter according to the present invention in the flow path direction. The imaginary line 15 has a contour that is smaller by a length of 2 × (partition wall pitch) toward the center of the end surface than the outer peripheral wall, and the flow path existing between the imaginary line 15 and the outer peripheral wall is plugged at both ends. ing. Here, the plugging material is filled into the flow path by a known technique, for example, after a masking film is disposed on the end face of the ceramic honeycomb structure, the perforated portions are alternately formed in the flow path of the honeycomb structure. Then, the end face of the ceramic honeycomb structure is dipped in a separately prepared ceramic slurry for plugging, and the ceramic slurry is introduced into the ceramic honeycomb structure through the perforated portion of the masking film. At this time, the ceramic slurry is introduced into all the channels near the outer peripheral wall by disposing no masking film for the channels near the outer peripheral wall. After the introduced slurry is solidified, the honeycomb structure is extracted from the ceramic slurry and dried to form a plugging material. Further, the other end side of the honeycomb structure is introduced in the same manner, ceramic slurry is introduced, solidified, and dried to form a plugging material, and then the masking film is peeled off. Thereafter, the plugging material is fired to integrate the partition walls and the plugging material, thereby obtaining a ceramic honeycomb filter in which predetermined flow paths on the exhaust gas inflow side and the outflow side are plugged. The introduction of the ceramic slurry into the predetermined flow path may be performed on the formed body of the ceramic honeycomb structure after drying, and the plugging material may be fired and integrated simultaneously with the formed body.

  Further, for the flow path near the outer peripheral wall of the ceramic honeycomb structure, a masking film is used to make the plugging length different from the flow path in the central part of the honeycomb structure. The ceramic slurry can be introduced into the flow path and the flow path in the vicinity of the outer peripheral wall in separate steps. For example, after placing a masking film on the end face of a ceramic honeycomb structure, perforations are formed alternately in the central flow path of the honeycomb structure, and perforations are formed in the flow path near the outer peripheral wall. Instead, the end face of the ceramic honeycomb structure is immersed in a separately prepared ceramic slurry for plugging, and the ceramic slurry is introduced into the ceramic honeycomb structure through the perforated portion of the masking film. After the introduced slurry is solidified, the honeycomb structure is extracted from the ceramic slurry, dried and fired, and the plugging material and the partition walls in the central channel are integrated. After that, a masking film is arranged over the entire flow path end face of the central part, and the ceramic slurry is introduced only into the flow path near the outer peripheral wall, solidified, dried and fired, and the central flow path and the flow path near the outer peripheral wall. Thus, honeycomb structures having different plugging material lengths can be obtained.

  Here, the embodiment of the present invention is not limited to the shape shown in FIGS. 3 to 4, and the shape of the other invention shown in FIG. Since it acts as an adiabatic air layer, there is no heat dissipation of the metal container from the outer wall of the filter, and the collected particulates can be efficiently burned and removed, and the pressure loss of the filter can be minimized. Decline can be prevented.

  The outer end face of at least a part of the plugging material plugging the flow path of the ceramic honeycomb filter, which is a preferred embodiment of the present invention, protrudes 0.01 to 5 mm in the flow path direction with respect to the partition wall end face. The ceramic honeycomb filter in which the protruding portion has an inclined surface at least with respect to the flow path direction can be manufactured as follows. First, a resin mask 21 in which an opening was formed in a resin material was prepared so that a projecting portion of a predetermined plugging material was obtained. Here, the opening having the inclined surface 21a can be formed by subjecting the resin plate material to machining, heating, or the like, or using an injection molding method or the like. Next, a plugging material slurry is prepared and, as shown in FIG. 10 (a), a predetermined opening end on one end side of the through hole of the honeycomb structure is closed with a resin mask 21 prepared in advance. Then, the slurry was immersed so as to obtain a predetermined depth on one end side of the honeycomb structure. After the slurry was dried, the resin mask 21 was removed to obtain a ceramic honeycomb filter in which the outer end face of the plugging material protruded from the end face of the partition wall as shown in FIG. At this time, a ceramic honeycomb filter having various protrusion lengths 23 in various forms can be obtained by adjusting the thickness of the resin mask, the angle of the opening inclined surface 21a, the plugging material slurry, and the like.

Hereinafter, although the actual example of this invention is demonstrated, this invention is not limited to them.
(Examples 1 to 4, Reference Examples 1 and 2 )
Cordierite such as kaolin, calcined kaolin, alumina, aluminum hydroxide, silica, talc, etc., so that SiO ₂ is 42 to 56 mass%, Al ₂ O ₃ is 30 to 45 mass%, and MgO is 12 to 16 mass%. A binder, a lubricant, and a pore former were added to the ceramic material powder and mixed. At this time, the particle size, particle size distribution, addition amount, etc. of the cordierite forming raw material powder and the pore former are adjusted so that various types of pore distributions of the porous partition walls after firing are obtained, and are shown in Table 1. Formulation NO. Six types of raw materials 1 to 6 were prepared. Next, water was added to the mixture to produce a plasticizable batch, and the batch was formed into a cylindrical honeycomb structure by a known extrusion method. Next, the molded body was dried with a microwave dryer and then dried with hot air, and then fired at a temperature condition of 1400 ° C. to obtain an outer diameter of 267 mm, a length of 304 mm, a partition pitch of 1.5 mm, and a partition wall thickness. A 0.3 mm ceramic honeycomb structure was obtained. These formulation NO. Table 1 shows the pore distribution and A-axis compressive strength of the partition walls of the ceramic honeycomb structure prepared in 1-6.

Here, the measurement of the total pore volume and the pore distribution is performed by using the mercury intrusion method, using Autopore III manufactured by Micromeritics, and the small piece cut out from the ceramic honeycomb filter is stored in the measurement cell as a test piece. After depressurizing the inside, mercury is introduced and pressurized, and the relationship between the pore size and the cumulative pore volume is obtained from the relationship between the pressure at this time and the volume of mercury pushed into the pores existing in the sample. . At this time, the pressure for introducing mercury was 0.5 psi (3.4 × 10 ⁻³ MPa), and the constants for calculating the pore diameter from the pressure were contact angle = 130 ° and surface tension of 484 dyne / cm. The total pore volume was the cumulative pore volume at a pressure of 60,000 psi (414 MPa) (corresponding to a pore diameter of 0.003 μm). The A-axis compressive strength was measured according to the standard M505-87 “Testing method for ceramic monolithic carrier for automobile exhaust gas purification catalyst” established by the Japan Society for Automotive Engineers.

  Then, these compounding NO. The ceramic honeycomb structure obtained from the raw materials 1 to 6 is plugged from a cordierite-forming raw material by a known technique so that the channel ends of the ceramic honeycomb structure are alternately plugged. After filling the stop material slurry, the plugging material slurry was dried and fired to obtain various cordierite ceramic honeycomb filters of Examples 1-6. Here, the length of the plugging material of the flow path was adjusted to 7 to 10 mm.

The obtained ceramic honeycomb filters of Examples 1 to 4 and Reference Examples 1 and 2 were evaluated for pressure loss and isostatic strength. The results are shown in Table 2.
Here, the pressure loss was measured by applying a carbon powder having an air flow rate of 7.5 Nm ³ / min and a particle size of 0.042 μm at a rate of 3 g / h to a ceramic honeycomb filter at a pressure loss test stand. The differential pressure between the inflow side and the outflow side after charging 1 g of powder / filter volume 1 L) was measured as pressure loss (mmAq), and the rate of increase relative to the pressure loss before charging carbon powder was calculated. Pressure loss increase rate = 100 × {(pressure loss after charging carbon 1 g / L) − (pressure loss before charging carbon)} / (pressure loss before charging carbon) (%). As a result, if the rate of increase in pressure loss is 25% or less, it will be accepted (△), if it is more preferably 20% or less, it will be (◯), more preferably 15% or less will be (◎), and if it exceeds 25%, it will fail. The pressure loss was evaluated as (×).

In addition, the isostatic strength test is based on the automobile standard (JASO) M505-87 issued by the Japan Society of Automotive Engineers, and the both ends of the ceramic honeycomb structure are contacted with 20 mm thick aluminum plates to seal both ends. At the same time, put the outer wall surface in close contact with 2 mm thick rubber into a pressure vessel, introduce water into the pressure vessel, apply hydrostatic pressure from the outer wall surface, and measure the pressure when destroyed The isostatic strength was used. The case where the isostatic strength is 1.5 MPa or more is determined to be acceptable (Δ), the case where 1.8 MPa or more is preferable (O), the case where 2 MPa or more is preferable (◎), and the case where it is less than 1.5 MPa Is indicated by a failure (x).
Then, as a comprehensive judgment, both the pressure loss and the isostatic strength are judged as (◯), (◎) as well as (◎), and (△) as one of them. The thing with ((triangle | delta)) and the thing which has (x) in any was evaluated by (x).

In the ceramic honeycomb filters of Reference Examples 1 and 2 , the total pore volume of the partition walls is 0.55 to 0.80 cm ³ / g, and the pore distribution of the porous partition walls is 2 μm or more. 55 to 0.80 cm ³ / g, 5 μm or more pore volume: 0.50 to 0.80 cm ³ / g, 10 μm or more pore volume: 0.40 to 0.70 cm ³ / g, 20 μm or more pore volume: 0.20~0.50cm ³ / g, 40μm or more pore volume: 0.05~0.25cm ³ / g, or more of the pore volume 100μm is 0.02~0.10cm ³ / g , Formulation NO. From the fact that using the 1, ceramic honeycomb structure produced from 6 of the raw material, the pressure loss, any evaluation of the isostatic strength of the pass (△), the comprehensive judgment by (◎) becomes (△) . In the ceramic honeycomb filters of Examples 1 to 4, the total pore volume of the partition walls is 0.57 to 0.80 cm ³ / g, and the pore distribution of the porous partition walls is 2 μm or more. 55 to 0.75 cm ³ / g, 5 μm or more pore volume: 0.54 to 0.74 cm ³ / g, 10 μm or more pore volume: 0.45 to 0.65 cm ³ / g, 20 μm or more pore volume: 0.25~0.45cm ³ / g, 40μm or more pore volume: 0.07~0.2cm ³ / g, or more of the pore volume 100μm is 0.02~0.08cm ³ / g , Formulation NO. Honeycomb structures made from 2 to 5 materials have a pressure loss and isostatic strength evaluation results of both (◯) and a comprehensive judgment of pass (○), which is a superior ceramic in terms of pressure loss and strength. It turns out that it is a honeycomb filter.

(Comparative Examples 1-2)
In the same manner as in Examples 1 to 4 and Reference Examples 1 and 2 , the blending NO. Two types of raw materials 7 to 8 were prepared, and water was added to produce a plasticizable batch. A cylindrical honeycomb structure was formed from this batch by a known extrusion method. Next, the molded body was dried with a microwave dryer and then dried with hot air, and then fired under a temperature condition of 1400 ° C., having four different characteristics, an outer diameter of 267 mm, and a length. A ceramic honeycomb structure having 304 mm, a partition pitch of 1.5 mm, and a partition wall thickness of 0.3 mm was obtained. These pore distributions and the A-axis compressive strength are shown in Table 1. Next, after filling these ceramic honeycomb structures with a plugging material slurry made of a cordierite forming material by a known technique in which the flow path ends of the ceramic honeycomb structures are alternately plugged. The plugging material slurry was dried and fired to obtain cordierite ceramic honeycomb filters of Comparative Examples 1 and 2. Here, the length of the plugging material is adjusted to be 7 to 10 mm.

Table 2 shows the results of evaluating the pressure loss and isostatic strength of these ceramic honeycomb filters in the same manner as in Examples 1 to 4 and Reference Examples 1 and 2. In the ceramic honeycomb filter of Comparative Example 1, the total pore volume of the partition walls is less than 0.57 cm ³ / g, and the pore distribution of the porous partition walls is a pore volume of 2 μm or more: 0.55 cm ³ / g. Pore volume of less than 5 μm: less than 0.54 cm ³ / g, pore volume of 10 μm or more: less than 0.45 cm ³ / g, pore volume of 20 μm or more: less than 0.25 cm ³ / g, Pore volume of 40 μm or more: less than 0.07 cm ³ / g, pore volume of 100 μm or more: less than 0.02 cm ³ / g Since the honeycomb structure made from the raw material No. 7 was used, the pore volume was small at all pore diameters, so the isostatic strength evaluation result was a pass (◎), but the pressure loss evaluation result Was rejected (x), the overall judgment was rejected (x), and a ceramic honeycomb filter having both pressure loss and strength could not be obtained.

In the ceramic honeycomb filter of Comparative Example 2, the total pore volume of the partition walls exceeded 0.80 cm ³ / g, and the pore distribution of the porous partition walls was 2 μm or more: 0.75 cm ³ / g More than 5 μm pore volume: More than 0.74 cm ³ / g More than 10 μm pore volume: More than 0.65 cm ³ / g More than 20 μm pore volume: 0.45 cm ³ / g More than 40 μm pore volume: more than 0.20 cm ³ / g and more than 100 μm pore volume: more than 0.08 cm ³ / g Since the honeycomb structure produced from the raw material of No. 8 was used, the pore volume was large in all pore diameters, so the evaluation result of pressure loss was acceptable (◎), but the evaluation result of isostatic strength was It was rejected (x), the overall judgment was rejected (x), and it was not possible to obtain a ceramic honeycomb filter having both pressure loss and strength.

(Examples 5 to 19, Reference Examples 3 to 17 )
In the same manner as in Examples 1 to 4 and Reference Examples 1 and 2 , the blending NO. A ceramic honeycomb structure having an outer diameter of 267 mm, a length of 304 mm, a partition wall pitch of 1.5 mm, and a partition wall thickness of 0.3 mm was obtained from the four types of raw materials 1, 3, 4, and 6 . For these ceramic honeycomb structures, the end portions of the channels of the ceramic honeycomb structure are alternately plugged, and both ends are plugged for the channels near the outer peripheral wall. After the masking film is disposed on the end face of the ceramic honeycomb structure, the perforated portions are alternately formed in the flow path at the center of the honeycomb structure, and the perforated portions are formed in the flow path near the outer peripheral wall. Without immersing the end face of the ceramic honeycomb structure in the ceramic slurry made of the cordierite raw material for plugging prepared separately, through the perforated part of the masking film, the ceramic slurry is introduced into the ceramic honeycomb structure, After the introduced slurry is solidified, the honeycomb structure is extracted from the ceramic slurry, dried, and the plugging material and partition walls in the central channel are integrated, After that, a masking film is arranged over the entire end face of the flow path in the center, and the ceramic slurry is introduced only into the flow path near the outer peripheral wall, solidified, dried, and fired, so that the flow path near the outer peripheral wall is plugged. Various cordierite ceramic honeycomb filters of Examples 5 to 19 and Reference Examples 3 to 17 were obtained. Here, the length of the plugging material of the flow path excluding the flow path in the vicinity of the outer peripheral wall was adjusted to be 7 to 10 mm.

For the obtained ceramic honeycomb filters of Examples 5 to 19 and Reference Examples 3 to 17 , pressure loss and isostatic strength were evaluated in the same manner as in Examples 1 to 4 and Reference Examples 1 and 2 , A comprehensive judgment was made. Furthermore, after capturing fine particles discharged from the diesel engine, the mass regeneration rate after the fine particles were burned and removed was evaluated.

  Here, the mass regeneration rate means (fine particle trapping amount−burning residual amount after regeneration) × 100 / (fine particle trapping amount) (%). The test results are as follows (△) when the mass regeneration rate is 80% or more, (◯) when 85% or more is preferable, and (◎) when 90% or more is preferable, and less than 80%. Cases are indicated by a failure (x).

  The results are shown in Table 3. In Table 3, the plugging length ratio of the plugging portions at both ends is (the length from the end surface of one plugging material in which the channel near the outer peripheral wall is plugged at both ends) × 100 / (Total length of the filter), and in this embodiment, the total filter length is 304 mm. Further, the range of the both end plugged portions on the end face indicates the range where the flow path having both ends plugged exists by the length from the outer peripheral wall to the center of the end face. These measurements are shown as average values measured at arbitrary five locations of the ceramic honeycomb filter broken by the isostatic test.

In the ceramic honeycomb filters of Examples 5 to 19 , the total pore volume of the partition walls is 0.57 to 0.80 cm ³ / g, and the pore distribution of the porous partition walls is 2 μm or more. 55 to 0.75 cm ³ / g, 5 μm or more pore volume: 0.54 to 0.74 cm ³ / g, 10 μm or more pore volume: 0.45 to 0.65 cm ³ / g, 20 μm or more Pore volume: 0.25 to 0.45 cm ³ / g, pore volume of 40 μm or more: 0.07 to 0.20 cm ³ / g, pore volume of 100 μm or more is 0.02 to 0.08 Formulation NO., which is cm ³ / g. The honeycomb structure produced from the raw materials of 3 and 4 is used, and the ceramic honeycomb filters of Reference Examples 3 to 17 have a total pore volume of partition walls of 0.55 to 0.80 cm ³ / g, The pore distribution of the porous partition walls is a pore volume of 2 μm or more: 0.55 to 0.80 cm ³ / g, a pore volume of 5 μm or more: 0.50 to 0.80 cm ³ / g, a pore of 10 μm or more Volume: 0.40 to 0.70 cm ³ / g, pore volume of 20 μm or more: 0.20 to 0.50 cm ³ / g, pore volume of 40 μm or more: 0.05 to 0.25 cm ³ / g, 100 μm The above-mentioned pore volume is 0.02-0.10 cm < ³ > / g, compounding NO. Evaluation results of pressure loss and isostatic strength because the honeycomb structure manufactured from the raw materials 1 and 6 is used and the flow path near the outer peripheral wall of the ceramic honeycomb filter is plugged at both ends. Are acceptable (Δ) to (◎), indicating that a ceramic honeycomb filter excellent in pressure loss and strength can be obtained. Further, in the ceramic honeycomb filters of Examples 5 to 19 and Reference Examples 3 to 17, both ends of the flow path near the outer peripheral wall are plugged, and the corners of the honeycomb filter are reinforced, so that the isostatic strength is high. The evaluation is (◯) or (◎), both of which are acceptable, and the both ends of the flow path in the vicinity of the outer peripheral wall are not plugged with the plugging material. The ceramics of Reference Examples 1 and 2 and Examples 2 and 3 The strength characteristics are improved as compared with the isostatic strength (Δ) or (◯) of the honeycomb filter. Furthermore, from the evaluation results of the mass regeneration rate, the ceramic honeycomb filters of Reference Examples 6 and 7 , Examples 8 and 9 , Examples 17 and 18 , and Examples 15 and 16 have a range of plugging portions at both ends on the end surface of 2. X (partition wall pitch), and the plugging length ratio of the plugging portions at both ends is 3.3% or less, so that the heat insulation space is sufficiently secured. (A), and it can be seen that the fine particles are burned well. Further, in the ceramic honeycomb filters of Reference Examples 11 to 14 and Examples 13 to 16 , the range of the plugging portions at both ends on the end face is (4 to 6) × (partition wall pitch), so that a sufficient heat insulating space is secured. Therefore, it can be seen that the evaluation result of the mass regeneration rate is (◎), and the fine particles are burned well. However, among these, the ceramic honeycomb filters of Reference Example 14 and Example 16 had a pressure loss evaluation of (Δ) because the range of both end plugging portions on the end face was 6 × (partition wall pitch).

( Reference Examples 18-29 )
Similar to Example 1 , the formulation NO. After mixing and kneading 2 cordierite forming materials and forming a honeycomb structure by a known extrusion molding method, plugging is performed on predetermined flow paths at both ends, firing at 1400 ° C., and outer diameter of 295 mm A ceramic honeycomb structure having a length of 304 mm, a partition wall pitch of 1.5 mm, and a partition wall thickness of 0.3 mm was obtained. Table 1 shows the pore distribution and the A-axis compressive strength of this honeycomb structure. Thereafter, the peripheral portion of the fired body was removed by processing, and a ceramic honeycomb structure having an outer diameter of 284 mm having a groove extending in the axial direction on the outer peripheral surface after processing.

  Next, a resin mask 21 in which an opening was formed in the resin material was prepared so that a predetermined plugging material protrusion was obtained. Here, the opening having the inclined surface 21a can be formed by subjecting the resin plate material to machining, heating, or the like, or using an injection molding method or the like. Next, a plugging material slurry made of a cordierite forming raw material is prepared, and a predetermined opening end portion on one end side in the through hole of the honeycomb structure is closed with a resin mask 21 prepared in advance. The slurry was immersed so as to obtain a predetermined depth on one end side of the structure. After the slurry was dried, the resin mask 21 was removed to obtain a ceramic honeycomb filter plugged with a plugging material whose outer end face of the plugging material protruded from the end face of the partition wall. At this time, by adjusting the thickness of the resin mask, the angle of the opening inclined surface 21a, the plugging material slurry, etc., FIGS. 6 (a), 6 (b), 8 (g), 8 (n). The ceramic honeycomb structures of Examples 37 to 48 having various protrusion lengths 23 in the form of Subsequently, the plugging material was fired after forming the plugging portions on the other end surface side in the same manner. The projection length of the plugging material at this time was calculated as an average value of measured values at arbitrary five locations for the plugging material on the exhaust gas inflow side end face of the ceramic honeycomb structure. Here, the length of the plugging material was unified to approximately 9 mm (the plugging length ratio with respect to the entire length is 3%). Further, the surface roughness Ry of the outer surface of the plugging material was 76 μm.

  Next, a cordierite slurry prepared by adding 10 parts by weight of colloidal silica to 100 parts by weight of cordierite powder having an average particle diameter of 15 μm and further adding a binder, water, and the like to the outer peripheral surface of the ceramic honeycomb structure is applied. To form an outer peripheral wall. Thereafter, the outer peripheral wall was dried and fired, and the outer diameter was 267 mm, the length was 304 mm, the partition wall thickness was 0.3 mm, the partition wall pitch was 1.47 mm, and the outer wall thickness was 1.5 mm. 37 to 48 cordierite ceramic honeycomb filters were obtained.

Table 4 shows the results of evaluating the pressure loss and isostatic strength of the ceramic honeycomb filters of Reference Examples 18 to 29 . The ceramic honeycomb filters of Reference Examples 18 to 29 are blended NO. The determination of the pressure loss of the ceramic honeycomb filter of Example 1 manufactured with the honeycomb structure obtained from No. 2 was (◯), whereas the end face shape of the plugging material was 0.01 to Since the protrusion protrudes 5 mm and the protruding portion has an inclined surface at least in the flow path direction, accumulation of fine particles hardly occurs on the end surface of the inflow side plugged portion 1a, and the evaluation of pressure loss is (◎). It turns out that it is improving.

( Reference Examples 30 to 35 )
As in Example 2 , the formulation NO. No. 3 cordierite forming raw material was mixed and kneaded, and a honeycomb structure was formed by a known extrusion molding method, then plugged into predetermined flow paths at both ends, fired at 1400 ° C., and an outer diameter of 295 mm A ceramic honeycomb structure having a length of 304 mm, a partition wall pitch of 1.5 mm, and a partition wall thickness of 0.3 mm was obtained. Table 1 shows the pore distribution and the A-axis compressive strength of this honeycomb structure. Thereafter, the peripheral edge portion of the fired body was removed by processing, and a ceramic honeycomb structure having an outer diameter of 284 mm having a groove extending in the axial direction on the outer peripheral surface after processing on the outer peripheral surface after processing.

  Next, a resin mask 21 in which an opening was formed in the resin material was prepared so that a predetermined plugging material protrusion was obtained. Here, the opening having the inclined surface 21a can be formed by subjecting the resin plate material to machining, heating, or the like, or using an injection molding method or the like. Next, a plugging material slurry is prepared, and a predetermined opening end on one end side of the through hole of the honeycomb structure is closed with a resin mask 21 prepared in advance, The slurry was immersed so as to obtain a predetermined depth. Here, regarding the flow path in the vicinity of the outer peripheral wall existing in the range of (1 to 4) × (partition wall pitch) from the outer peripheral wall of the honeycomb filter end face toward the end face center of the honeycomb filter, No mask was placed so that plugging material could be introduced into the path. After the slurry is dried, by removing the resin mask 21, the outer end face of the plugging material protrudes from the end face of the partition wall, and the flow path in the vicinity of the outer peripheral wall is (1-4) × (partition pitch) from the outer peripheral wall. ), A ceramic honeycomb structure in which all the channels were plugged was obtained. At this time, by adjusting the thickness of the resin mask, the angle of the opening inclined surface 21a, the plugging material slurry, and the like, the protrusion length 23 is 0 in the form of FIGS. 6 (a) and 6 (b). Ceramic honeycomb structures of Examples 49 to 54 having a diameter of 14 mm were obtained. Subsequently, the plugging material was fired after forming the plugging portions on the other end surface side in the same manner. The projection length of the plugging material at this time was calculated as an average value of measured values at arbitrary five locations for the plugging material on the exhaust gas inflow side end face of the ceramic honeycomb structure. Here, the length of the plugging material was unified to approximately 9 mm (the plugging length ratio with respect to the entire length is 3%). Further, the surface roughness Ry of the outer surface of the plugging material was 76 μm.

Next, a cordierite slurry prepared by adding 10 parts by mass of colloidal silica to 100 parts by mass of silica powder having an average particle size of 15 μm and further adding a binder, water, etc. is applied to the outer peripheral surface of the ceramic honeycomb structure. An outer peripheral wall was formed. Then, drying of the outer peripheral wall and fired, the outer diameter 267 mm, length 304 mm, partition wall thickness of 0.3 mm, a pitch of the partition walls is 1.47 mm, the thickness of the outer peripheral wall is 1.5 mm, reference example 30 to 35 cordierite ceramic honeycomb filters were obtained.

Table 5 shows the results of evaluation of pressure loss, isostatic strength, and mass regeneration rate for the ceramic honeycomb filters of Reference Examples 30 to 35 . The ceramic honeycomb filters of Reference Examples 30 to 35 are blended NO. The determination of the pressure loss and isostatic strength of the ceramic honeycomb filter of Example 2 manufactured with the honeycomb structure obtained from No. 3 was both (◯), whereas both ends of the flow path near the outer peripheral wall were visible. Since the corners of the honeycomb filter are reinforced, the evaluation of isostatic strength is improved as (◎), and the end face shape of the plugging material protrudes from the end face of the partition wall by 0.14 mm, and Since the protruding portion has an inclined surface in at least the flow path direction, the accumulation of fine particles on the end face of the inflow side plugged portion 1a hardly occurs, and the evaluation of the pressure loss is improved to (◎). In both cases, the overall judgment is (◎), and it can be seen that a ceramic honeycomb filter having both low pressure loss and high strength can be obtained.

It is a front view showing an example of a ceramic honeycomb filter. It is principal part sectional drawing which shows an example of the usage example of a ceramic honeycomb filter. It is a front view which shows an example of the ceramic honeycomb filter of this invention. It is principal part sectional drawing which shows an example of the ceramic honeycomb filter of this invention. It is a figure which shows the relationship between the pore diameter of the ceramic honeycomb filter of this invention, and a cumulative pore volume. FIG. 3 is an enlarged view of a plugged portion of a preferred example of the ceramic honeycomb filter of the present invention. It is an enlarged view of a plugged portion of an example of a conventional ceramic honeycomb filter. It is another example of the plugged shape of the ceramic honeycomb filter of the present invention. It is a schematic schematic sectional drawing of the other example of the ceramic honeycomb filter of this invention. It is a schematic cross section of an example for carrying out plugging of a preferred ceramic honeycomb filter of the present invention. (A) State in which resin mask is installed (b) State in which resin mask is removed

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a: Inflow side plugging material 1b: Outflow side plugging material 1c: Plugging material of the both ends of the flow path near an outer peripheral wall 1d: The inclined surface formed in the protrusion part 1e: Ceramics for plugging materials Rally 2a: inflow side exhaust gas 2b: outflow side exhaust gas 11: ceramic honeycomb filter 11a: outer peripheral wall 11b: partition wall 11c: flow path 12: storage container 13a, 13b: support member 14: support member 15: plugging material Outer end face 16: Outer end face 17 of the partition wall: Corner 18 formed between the plugging material protruding portion and the end face of the partition wall 21: Gap 21: Resin mask 21a: Inclined surface 22 of the resin mask opening: Plugging Material slurry container 23: protrusion length 24: plugging material length 25: corner 51 formed at the outflow side end of the inclined surface of the protrusion portion: lower limit of the total pore volume of the ceramic honeycomb filter of the present invention Point 52 indicating: ceramic of the present invention Point 53 showing the upper limit of the total pore volume of the Nicham filter 53: Point showing the lower limit of the cumulative pore volume of the ceramic honeycomb filter of the present invention having a pore diameter of 100 μm or more 54: Accumulation of the ceramic honeycomb filter of the present invention having a pore diameter of 100 μm or more Point 55 indicating the upper limit of the pore volume: Point 56 indicating the preferred lower limit of the cumulative pore volume when the pore diameter of the ceramic honeycomb filter of the present invention is 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 40 μm or more. Point 57 indicating the upper limit of the preferred cumulative pore volume at a pore diameter of 2 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 40 μm or more of the honeycomb filter: pore distribution of the ceramic honeycomb filter of Example 2 of the present invention

Claims (2)

A ceramic honeycomb filter that removes particulates contained in exhaust gas by plugging a predetermined flow path end of the ceramic honeycomb structure and allowing the exhaust gas to pass through a porous partition wall defining the flow path. The total pore volume of the porous partition wall is 0.57 to 0.80 cm ³ / g, and the pore volume of 2 μm or more: 0.55 to 0.75 cm ³ / g, the pore volume of 5 μm or more. : 0.54 to 0.74 cm ³ / g, 10 μm or more pore volume: 0.45 to 0.65 cm ³ / g, 20 μm or more pore volume: 0.25 to 0.45 cm ³ / g, 40 μm or more pore volume: 0.07~0.20cm ³ / g, a ceramic honeycomb filter, characterized in that 100μm or more of the pore volume is 0.02~ 0.08 ^cm 3 / g. 2. The ceramic honeycomb filter according to claim 1, wherein a flow path near the outer peripheral wall of the ceramic honeycomb filter is plugged at both ends.