JP2018183709A - Honeycomb filter and method for producing honeycomb filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb filter which can achieve high filtration efficiency without much higher pressure loss.SOLUTION: A honeycomb filter has a porous honeycomb structure, and contains cordierite as a main component, where a pore size distribution of the porous honeycomb structure satisfies all of the following conditions: (a) D1<7 μm; (b) 10 μm≤D50≤14 μm; and (c) 0.10≤(D90-D10)/D50≤0.78, D1 represents a pore size when 1% of the total pore size volume has a pore size smaller than it, D10 represents a pore size when 10% of the total pore size volume has a pore size smaller than it, D50 represents a pore size when 50% of the total pore size volume has a pore size smaller than it, so-called a median size, and D90 represents a pore size when 90% of the total pore size volume has a pore size smaller than it.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a honeycomb filter and a method for manufacturing a honeycomb filter.

  Conventionally, a honeycomb filter has been used to remove a collected substance from a fluid containing the collected substance. For example, fine particles such as carbon particles contained in exhaust gas discharged from an internal combustion engine of a diesel engine are used. It is used as a ceramic filter (Diesel Particulate Filter) for collecting and a ceramic filter (Gasoline Particulate Filter) for gasoline engines. The honeycomb filter has a plurality of parallel flow paths partitioned by partition walls, and one end of a part of the plurality of flow paths and the other end of the remaining part of the plurality of flow paths are sealed.

  As the honeycomb filter, filters having a controlled pore diameter distribution described in Patent Documents 1 to 3 below are known.

US Pat. No. 7,744,670 JP 2002-219319 A US Pat. No. 6,827,754

  Recently, it has been required to increase the filtration (collection) efficiency of smaller particles for honeycomb filters. However, in order to increase the filtration efficiency (especially the filtration efficiency of small particles), there is a problem that pressure loss generally increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a honeycomb filter capable of realizing high filtration efficiency without excessively increasing pressure loss and a method for manufacturing the honeycomb filter.

The honeycomb filter according to the present invention includes a porous honeycomb structure having a plurality of flow paths, one end of a part of the plurality of flow paths, and a remaining flow in the plurality of flow paths. A plurality of sealing portions for closing the other end of the road. The main component of the porous honeycomb structure is cordierite. The pore size distribution of the porous honeycomb structure satisfies all the following conditions.
(1a) D1 <7 μm
(1b) 10 μm ≦ D50 ≦ 14 μm
(1c) 0.10 ≦ (D90−D10) /D50≦0.78

  Here, D1 is a pore diameter in which 1% of the total pore volume has a smaller pore diameter, and D10 has a pore diameter in which 10% of the total pore volume has a smaller pore diameter. D50 is a so-called median diameter in which 50% of the total pore volume has a smaller pore diameter, and D90 is 90% of the total pore volume. The pore diameter has a smaller pore diameter.

  In the honeycomb filter, the porosity of the porous honeycomb structure may be 60 to 70%.

A method for manufacturing a honeycomb filter according to the present invention includes a step of forming a mixture including an inorganic raw material containing a constituent element of cordierite, a binder, a pore former, and a solvent to obtain a formed body, and firing the formed body. A step of obtaining a porous honeycomb structure having a plurality of flow paths, and a step of sealing one end of each of the plurality of flow paths of the molded body or the porous honeycomb structure.
The volume-based particle size distribution measured by the laser diffraction particle size distribution measurement method of the pore former satisfies all the following conditions.
(2a) 10 μm ≦ D′ 50 ≦ 32 μm
(2b) 0.5 ≦ (D′ 90−D′10) /D′50≦1.0
Here, D'10 is accumulated from the smaller particle size and corresponds to a cumulative particle size of 10%, D'50 is accumulated to a particle size corresponding to 50%, and D'90 is accumulated from the smaller particle size. The particle size corresponds to a cumulative 90%.

  ADVANTAGE OF THE INVENTION According to this invention, the honey-comb filter which can implement | achieve high filtration efficiency, without making pressure loss too high, and its manufacturing method are provided.

FIG. 1 is a cross-sectional view along the axial direction of a honeycomb filter according to an embodiment of the present invention. FIG. 2 is a cross-sectional view in a direction perpendicular to the axis of the honeycomb filter according to one embodiment of the present invention. FIG. 3 is a cross-sectional view in a direction perpendicular to the axis of a honeycomb filter according to another embodiment of the present invention.

  A honeycomb filter 100 according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the honeycomb filter 100 includes a porous honeycomb structure 120 and a sealing portion 130.

  The porous honeycomb structure 120 has a columnar shape and has an inlet end face (one end) 100a and an outlet end face (the other end) 100b. The porous honeycomb structure 120 has a plurality of flow paths 110. Sealing portions 130 are respectively provided at the end portions of some of the flow channels 110 on the outlet end surface 100b side, and these partial flow channels 110 have inlets whose inlet end surfaces 100a are opened and whose outlet end surfaces 100b are sealed. A flow path 110a is formed. Sealing portions 130 are respectively provided at the ends of the remaining flow paths 110 on the inlet end face 100a side. The remaining flow paths 110 are outlet flow paths 110b in which the inlet end face 100a is sealed and the outlet end face 100b is opened. Form.

  The cross-sectional shapes of the inlet channel 110a and the outlet channel 110b can be, for example, a circle, an ellipse, a quadrangle, a hexagon, and an octagon. In the porous honeycomb structure 120, each inlet channel 110 a is adjacent to at least one outlet channel 110 b via a partition wall W.

  The arrangement of the inlet channel 110a and the outlet channel 110b in the porous honeycomb structure is not particularly limited. The inlet channel 110a may be adjacent to at least one outlet channel 110b, the inlet channel 110a may be adjacent to another inlet channel, or the outlet channel 110b may be adjacent to another outlet channel. May be.

  Specifically, for example, as illustrated in FIG. 2, the inlet channel 110 a is adjacent to the three other inlet channels 110 a and is adjacent to the three outlet channels 110 b. 110a and the outlet channel 110b may be regularly arranged. In this case, one outlet channel 110b is adjacent to the six inlet channels 110a, and is not adjacent to the other outlet channels 110b. Each flow path is adjacent to a total of 6 other flow paths through partition walls W. The aggregate of the partition walls W constitutes the porous honeycomb structure 120.

  Further, as shown in FIG. 3, the inlet channel 110a and the outlet channel are arranged so that one inlet channel 110a is adjacent to the four other inlet channels 110a and adjacent to the two outlet channels 110b. 110b may be regularly arranged. One outlet channel 110b is adjacent to the six inlet channels 110a, and is not adjacent to the other outlet channels 110b. Thus, each channel is adjacent to a total of six other channels.

  The thickness of each partition wall W is preferably 5 to 12 mils, that is, 0.125 to 0.30 mm, more preferably 6 to 10 mils, that is, 0.15 to 0.25 mm, and 6 to 8 mils, that is, 0.15 to 0.15. 0.20 mm is more preferable.

  The cell density, that is, the density of the flow path (cell) in the cross section orthogonal to the axis of the porous honeycomb structure can be set to 150 to 350 cpsi, for example.

  The main component, that is, the maximum component of the porous honeycomb structure 120 is cordierite. The porous honeycomb structure preferably contains 50% by mass or more of cordierite, preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass.

Cordierite is a compound composed of about 48% to about 52% by weight of SiO ₂ component, about 32% to about 36% by weight of Al ₂ O ₃ component, and about 12% to about 15% by weight of MgO component And usually forms a crystalline phase.

In the present embodiment, the pore size distribution of the porous honeycomb structure 120 satisfies all the following conditions (1a) to (1c).
(1a) D1 <7 μm
(1b) 10 μm ≦ D50 ≦ 14 μm
(1c) 0.10 ≦ (D90−D10) /D50≦0.78

  Here, D1 is a pore diameter in which 1% of the total pore volume has a smaller pore diameter, and D10 has a pore diameter in which 10% of the total pore volume has a smaller pore diameter. D50 is a so-called median diameter in which 50% of the total pore volume has a smaller pore diameter, and D90 is 90% of the total pore volume. It is a pore diameter having a smaller pore diameter.

  Moreover, D10 can be 8-12 micrometers. D90 can be 16-25 μm. D99 can be 85-150 μm. Dn (n is a real number of 0 to 100) is a pore diameter in which n% of the total pore volume has a smaller pore diameter.

  From the viewpoint of filtration efficiency, D15 is preferably less than 10 μm, and more preferably less than 9.5 μm. The pore size volume (Σ0-10 μm) of 10 μm or less is preferably larger than 15% of the total particle volume.

The narrower the pore size distribution, the higher the filtration efficiency without increasing the pressure loss. Therefore, (D90-D10) / D50 is preferably 0.30 to 0.70. More preferably, it is 40-0.65.
Further, 0.10 ≦ (D50−D10) /D50≦0.25.

  The pore size distribution of the porous honeycomb structure 120 can be measured by a mercury intrusion method (contact angle: 130 °, surface tension: 485 dyne / cm).

  The porosity of the porous honeycomb structure 120 is preferably 60 to 70%. If it is less than 60%, the pressure loss tends to increase, and if it exceeds 70%, the filtration efficiency tends to decrease.

  Although the material of the sealing part 130 is not specifically limited, It is preferable that it is a ceramic material, and can be the ceramic which has a cordierite as a main component similarly to the porous honeycomb structure 120. FIG. The sealing part 130 can be porous and can have the same pore size distribution as the porous honeycomb structure.

  A honeycomb filter having such a porous structure can realize high filtration efficiency without increasing pressure loss so much. This honeycomb filter can be used as an exhaust gas filter for a gasoline engine. In general, the particle size of particles generated from a gasoline engine is considered to be smaller than the particles generated from a diesel engine, and the filtration efficiency of particles in gasoline engine exhaust gas is compared with the filtration efficiency of particles in diesel engine exhaust gas. Tends to be low. However, in the porous honeycomb structure according to the present embodiment, it is possible to improve the filtration efficiency without excessively increasing the pressure loss by narrowing the width of the pore diameter distribution and making D50 smaller than the conventional one. High filtration efficiency can be achieved even with gasoline engine exhaust gas.

(Honeycomb filter manufacturing method)
Next, an embodiment of a method for manufacturing a honeycomb filter will be described. A method for manufacturing a honeycomb filter includes, for example, a raw material preparation step for preparing an inorganic raw material powder containing a constituent element of cordierite and a raw material mixture containing an additive, and forming a raw material mixture to obtain a molded body having a plurality of channels. A molding step and a firing step of firing the molded body, and a step of sealing one end of each flow path between the molding step and the firing step or after the firing step.

(Raw material preparation process)
In the raw material preparation step, various inorganic raw material powders containing constituent elements of cordierite and additives are mixed and then kneaded to prepare a raw material mixture.

  The inorganic raw material powder containing the constituent elements of cordierite is a mixture containing a magnesium source, an aluminum source, and a silicon source.

Examples of the magnesium source contained in the mixture are magnesium oxide and talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ). Moreover, the compound guide | induced to magnesia by baking alone in the air is also mentioned. Examples of such a compound include magnesium salt, magnesium alkoxide, magnesium hydroxide, magnesium nitride, and magnesium metal.

  Specific examples of magnesium salts include magnesium chloride, magnesium perchlorate, magnesium phosphate, magnesium pyrophosphate, magnesium oxalate, magnesium nitrate, magnesium carbonate, magnesium acetate, magnesium sulfate, magnesium citrate, magnesium lactate, and magnesium stearate. , Magnesium salicylate, magnesium myristate, magnesium gluconate, magnesium dimethacrylate, magnesium benzoate and the like.

Examples of the aluminum source are alumina (aluminum oxide), aluminum hydroxide, kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ). Moreover, the compound guide | induced to an alumina by baking alone in the air is also mentioned. Examples of such a compound include aluminum salts, aluminum alkoxides, and metal aluminum.

  Examples of the crystal type of alumina include γ type, δ type, θ type, and α type, and may be amorphous. As the alumina, α-type alumina is preferable.

  The aluminum salt may be an inorganic salt with an inorganic acid or an organic salt with an organic acid. Specific examples of the aluminum inorganic salt include aluminum nitrates such as aluminum nitrate and ammonium nitrate, and aluminum carbonates such as ammonium aluminum carbonate. Examples of the aluminum organic salt include aluminum oxalate, aluminum acetate, aluminum stearate, aluminum lactate, and aluminum laurate.

  Specific examples of the aluminum alkoxide include aluminum isopropoxide, aluminum ethoxide, aluminum sec-butoxide, aluminum tert-butoxide, and the like.

  Examples of the crystal type of aluminum hydroxide include a gibbsite type, a bayerite type, a norosotrandite type, a boehmite type, and a pseudoboehmite type, and may be indefinite (amorphous). Examples of the amorphous aluminum hydroxide include an aluminum hydrolyzate obtained by hydrolyzing an aqueous solution of a water-soluble aluminum compound such as an aluminum salt or an aluminum alkoxide.

Examples of the silicon source include silicon oxide (quartz, amorphous silica), talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ), and kaolin (Al ₂ Si ₂ O ₅ (OH) ₄ ). Moreover, the powder of the compound guide | induced to a silica by baking alone in the air is also mentioned. Examples of such compounds include silicic acid, silicon carbide, silicon nitride, silicon sulfide, silicon tetrachloride, silicon acetate, sodium silicate, sodium orthosilicate, glass frit and the like.

  The inorganic raw material powder containing the constituent elements of cordierite preferably contains talc, kaolin and silica.

  As for the particle diameter of the talc used, D′ 50 is preferably 5 to 30 μm, more preferably 10 to 20 μm. Here, D'50 is a particle size corresponding to a cumulative 50%. The particle size distribution is a volume-based particle size distribution obtained by a laser diffraction particle size distribution measurement method.

  Regarding the particle diameter of the kaolin used, D′ 50 is preferably 1 to 20 μm, and more preferably 1 to 10 μm.

About the particle size of the silica to be used, D′ 50 is preferably 1 to 20 μm, and more preferably 3 to 10 μm. The particle size distribution of silica satisfies the following formula (a). Here, D′ 10 is a particle size corresponding to 10% cumulative from the smaller particle size, and D′ 90 is a particle size corresponding to 90% cumulative from the smaller particle size.
(A) (D'90-D'10) / D'50 <2.0

  Moreover, the inorganic raw material powder containing the constituent elements of cordierite may be partially or entirely cordierite powder.

The blending amount of each component is appropriately adjusted so that the SiO ₂ component, Al ₂ O ₃ component, and MgO component fall within the above cordierite composition range. The particle diameter D′ 50 of the inorganic raw material powder containing the constituent elements of cordierite can be 1 to 30 μm.

  Examples of the additive include a pore former (pore forming agent), a binder, a lubricant, a plasticizer, and a solvent.

  As the pore former, a material formed by a material that disappears at a temperature lower than the temperature at which the molded body is degreased and fired in the firing step can be used. In degreasing and firing, when the molded body containing the pore former is heated, the pore former disappears due to combustion or the like. As a result, a space is created at the location where the pore former was present, and the inorganic raw material powder located between the spaces contracts during firing to form a communication hole in the partition wall through which fluid can flow. can do.

  The pore former is, for example, organic powder, carbon powder, or dry ice powder. Examples of organic powders are corn starch, barley starch, wheat starch, tapioca starch, bean starch, rice starch, pea starch, and potato starch (potato starch). Examples of resin powders are polyethylene powder, hollow resin powder (a compound having an ether structure which is gasified at a temperature below the softening point of the thermoplastic resin and does not contain chlorine or bromine inside the thermoplastic resin as an outer shell. Is a thermally expandable microsphere). An example of carbon powder is graphite. Content of a pore former is 10-50 mass parts with respect to 100 mass parts of inorganic raw material powder, for example, and 20-40 mass parts is preferable.

  The particle size distribution of the pore former satisfies the following formulas (2a) and (2b). Here, D'10 is accumulated from the smaller particle size and corresponds to a cumulative particle size of 10%, D'50 is accumulated to a particle size corresponding to 50%, and D'90 is accumulated from the smaller particle size. The particle size corresponds to a cumulative 90%. The particle size distribution is a volume-based particle size distribution obtained by a laser diffraction particle size distribution measurement method.

(2a) 10 μm ≦ D′ 50 ≦ 30 μm
(2b) 0.5 ≦ (D′ 90−D′10) /D′50≦1.0
(D′ 90−D′10) / D′ 50 may be 0.95 or less, or 0.9 or less.

  Note that D′ 15 can be 10 μm or less. Note that D′ n (n is a real number from 0 to 100) is a particle size corresponding to the cumulative n% accumulated from the smaller particle size.

  Moreover, the volume (Σ0-10 μm) of the pore former having a particle diameter of 10 μm or less can be less than 15% of the total particle volume.

  The binder is, for example, celluloses such as methylcellulose, carboxymethylcellulose, hydroxyalkylmethylcellulose, sodium carboxymethylcellulose; alcohols such as polyvinyl alcohol; salts such as lignin sulfonate; waxes such as paraffin wax and microcrystalline wax. The content of the binder in the raw material mixture is, for example, 20 parts by mass or less with respect to 100 parts by mass of the inorganic raw material powder.

  Lubricants or plasticizers include, for example, alcohols such as glycerin; higher fatty acids such as caprylic acid, lauric acid, palmitic acid, alginic acid, oleic acid and stearic acid; stearic acid metal salts such as stearic acid A1, polyoxyalkylene alkyl Ether. The content of the lubricant or plasticizer in the raw material mixture is, for example, 10 parts by mass or less with respect to 100 parts by mass of the inorganic raw material powder.

  Examples of the solvent include water and alcohol. Water is preferably ion-exchanged water because it has few impurities. When a raw material mixture contains a solvent, the content rate of a solvent is 10-100 mass parts with respect to 100 mass parts of inorganic raw material powders, for example.

(Molding process)
In the forming step, a green honeycomb formed body having a honeycomb structure having a plurality of flow paths is obtained. In the step of forming the mixture, for example, it may be formed into the shape of the target green honeycomb by using a forming device such as a uniaxial press or an extrusion molding machine similar to those usually used.

(Baking process)
In the firing step, the honeycomb structured green honeycomb formed body obtained in the forming step is fired to obtain a fired porous honeycomb structure. In the firing step, calcination (degreasing) for removing a binder or the like contained in the molded body (in the raw material mixture) may be performed before the molded body is fired. In the firing of the molded body, the firing temperature is usually 1300 ° C. or higher, preferably 1400 ° C. or higher. Moreover, a calcination temperature is 1500 degrees C or less normally, Preferably it is 1450 degrees C or less. The temperature raising rate is not particularly limited, but is usually 1 to 500 ° C./hour. When the pore former is organic powder or carbon powder, it is preferable to perform firing in an oxygen-containing atmosphere. Firing is usually performed using a conventional firing furnace such as a tubular electric furnace, a box-type electric furnace, a tunnel furnace, a microwave heating furnace, a rotary furnace, a roller hearth furnace, or a gas firing furnace. The firing time may be a time sufficient for the inorganic raw material powder to transition to the cordierite crystal, and varies depending on the amount of the raw material, the type of the firing furnace, the firing temperature, the firing atmosphere, etc., but usually 5 to 24 hours. It is.

(Sealing process)
The sealing step is performed between the molding step and the firing step or after the firing step. When a sealing step is performed between the forming step and the firing step, one end of each flow path of the green honeycomb molded body obtained in the forming step is sealed with a sealing agent, and then green in the firing step. By firing the sealing agent together with the honeycomb formed body, a honeycomb structure including a sealing portion that seals one end of each flow path is obtained. When performing the sealing step after the firing step, after sealing one end of each flow path of the honeycomb fired body obtained in the firing step with a sealing agent, by firing the sealing agent together with the honeycomb fired body, A honeycomb structure including a sealing portion that seals one end of each flow path is obtained. As the sealing agent, a mixture similar to the raw material mixture for obtaining the green honeycomb molded body can be used.

  According to the manufacturing method according to the present embodiment, the honeycomb filter having the porous structure described above can be easily obtained.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above embodiment, the inlet channel 110a and the outlet channel 110b are closed by the plug-shaped sealing part 130, but other sealing methods may be adopted. For example, the partition wall at the end of the porous honeycomb molded body is reduced toward the end face of the honeycomb filter until the cross-sectional area of one of the flow paths increases and the cross-sectional area of the other flow path becomes zero. The sealing portion may be formed by deforming as described above and then firing.

Example 1
A cordierite raw material (talc, aluminum hydroxide, kaolin, silica), a pore former, a binder, and water were mixed, and a honeycomb formed body was prepared with an extruder.

  The amount of each raw material other than water was set to 24.2% by mass, 28.6% by mass, 5.0% by mass, 10.7% by mass, 25.3% by mass, and 6.2% by mass in this order. Potato starch A shown in Table 1 was used as a pore former. D′ 10, D′ 50, and D′ 90 were obtained based on the volume-based particle size distribution obtained by a laser diffraction particle size distribution analyzer. Further, in order to give plasticity suitable for extrusion molding, an appropriate amount of water and a lubricant were added to the mixture of the raw materials, and molding was performed. The formed honeycomb formed body had the shape shown in FIG. 2, and the density of hexagonal cells was 290 cpsi. The outer diameter was 25.4 mm, the height was 150.3 mm, and the wall thickness was 10.4 mil.

  One end or the other end of each flow path of the obtained honeycomb formed body was sealed by plugging using the same forming raw material as described above. Thereafter, the sealed honeycomb formed body was fired in an air atmosphere to obtain a honeycomb filter.

Measurement of the total pore volume and pore distribution was carried out by the mercury intrusion method using an Autopore III manufactured by Micromeritics. First, a small piece cut out from the honeycomb filter is stored in the measurement cell as a test piece, and after the pressure inside the cell is reduced, mercury is introduced and then the pressure is applied, and the pressure and the pores existing in the sample are pushed into this The relationship between the pore diameter and the cumulative pore volume was determined from the relationship with the mercury volume. 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: 485 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 Purifying Catalyst” established by the Society of Automotive Engineers of Japan.

(Examples 2-3, Comparative Examples 1-3)
Except for changing the type of pore former as shown in Table 1, it was the same as Example 1.

(Measurement of initial pressure loss)
At each gas flow rate of 2 m ³ / h, 4 m ³ / h, and 6 m ³ / h, gas was supplied to each filter at a gas temperature of room temperature of 25 ° C., and the initial pressure loss was measured in the absence of soot. . The results are shown in Table 2.

(Measurement of pressure loss due to accumulated soot)
Soot was gradually deposited on each filter at a soot generation rate of 1.3 g / h, a gas flow rate of 6 m ³ / h, and a gas temperature of room temperature, and the change in pressure loss was measured. The results are shown in Table 2.

(Measurement of filtration efficiency)
Soot generation rate is 1.3 g / h, gas flow rate is 6 m ³ / h, gas temperature is gradually deposited on each filter at room temperature, and particles in the gas discharged from the filter outlet are collected at regular intervals. The weight was measured and the change in filtration efficiency over time was determined. The results are shown in Table 2.

(Evaluation of porous structure of porous honeycomb structure)
A porous honeycomb structure was cut out from the honeycomb filter, and the pore size distribution was measured by a mercury intrusion method. The results are shown in Table 3.

  It was confirmed that the example satisfying the conditions (1a) to (1c) can achieve both high filtration efficiency and low stagnation pressure loss.

  DESCRIPTION OF SYMBOLS 100 ... Honeycomb filter, 120 ... Porous honeycomb structure, 110 ... Channel, 130 ... Sealing part.

Claims (3)

A porous honeycomb structure having a plurality of flow paths;
One end of a part of the plurality of channels, and a plurality of sealing portions for closing the other end of the remaining channel among the plurality of channels,
The main component of the porous honeycomb structure is cordierite,
A honeycomb filter in which the pore size distribution of the porous honeycomb structure satisfies all of the following conditions.
(1a) D1 <7 μm
(1b) 10 μm ≦ D50 ≦ 14 μm
(1c) 0.10 ≦ (D90−D10) /D50≦0.78
Here, D1 is a pore diameter in which 1% of the total pore volume has a smaller pore diameter, and D10 has a pore diameter in which 10% of the total pore volume has a smaller pore diameter. D50 is a so-called median diameter in which 50% of the total pore volume has a smaller pore diameter, and D90 is 90% of the total pore volume. The pore diameter has a smaller pore diameter.   The honeycomb filter according to claim 1, wherein the porosity of the porous honeycomb structure is 60 to 70%. A step of obtaining a molded body having a plurality of flow paths by molding a mixture containing an inorganic raw material containing cordierite, a binder, a pore former, and a solvent;
Firing the molded body to obtain a porous honeycomb structure; and
Sealing any one end of each of the plurality of flow paths of the molded body or the porous honeycomb structure, and
A method for manufacturing a honeycomb filter, wherein a volume-based particle size distribution measured by a laser diffraction particle size distribution measurement method of the pore former satisfies all the following conditions.
(2a) 10 μm ≦ D′ 50 ≦ 30 μm
(2b) 0.5 ≦ (D′ 90−D′10) /D′50≦1.0
Here, D'10 is accumulated from the smaller particle size and corresponds to a cumulative particle size of 10%, D'50 is accumulated to a particle size corresponding to 50%, and D'90 is accumulated from the smaller particle size. The particle size corresponds to a cumulative 90%.

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