JP2008221028A - Encapsulation method of ceramic honeycomb filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encapsulation method of a ceramic honeycomb filter of which the encapsulation part of the inflow side is arranged apart from the end face of a ceramic honeycomb structure and which prevents the enlargement of the pressure loss without narrowing the passage through which an exhaust gas flows because the passage is clogged due to the attachment of slurry as the encapsulation part to the diaphragm between the end face of the ceramic honeycomb structure through the encapsulation part. <P>SOLUTION: The encapsulation method of the ceramic honeycomb filter comprises a step (a) of inserting the distal end of a nozzle communicating with the space formed by the cylinder and the plunger into the passage, a step (b) of injecting the slurry as the encapsulation part stored in the space into the passage of the ceramic honeycomb structure from the distal end of the nozzle by proceeding the plunger, and a step (c) of making the pressure in the nozzle more lower than atmospheric pressure by retreating the plunger after the step of injection. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sealing method for a ceramic honeycomb filter used for purifying exhaust gas containing particulate matter (PM) discharged from a diesel engine.

  Exhaust gas from diesel engines and the like contains a large amount of PM mainly composed of carbon, and if this is released into the atmosphere, it will adversely affect the human body and the environment. For this reason, filters for collecting and purifying PM are mounted on exhaust system parts such as diesel engines.

  FIG. 3 is a schematic cross-sectional view of a conventional ceramic honeycomb filter 40 that collects and purifies PM in automobile exhaust gas. In FIG. 3, the ceramic honeycomb filter 40 includes an outer peripheral wall 1 having a substantially circular or substantially elliptical cross section perpendicular to the flow path direction, and a large number of flow paths surrounded by partition walls 2 on the inner peripheral side of the outer peripheral wall 1. Ceramic honeycomb structures (1) having 3 and 4 are alternately plugged in a checkered pattern with sealing portions 5 and 6 on the exhaust gas inflow side end surface 7 and the outflow side end surface 8, respectively. The outer peripheral wall is shown as 1 and the ceramic honeycomb structure is shown as (1).

  In the ceramic honeycomb filter 40 of FIG. 3, the exhaust gas is purified as follows. Exhaust gas (indicated by a dotted arrow) flows in from the flow path 3 opened in the inflow side end face 7. Since the outflow side end face 8 of the flow path 3 is sealed with the sealing portion 6, the exhaust gas passes through the pores (not shown) formed in the partition wall 2 and then adjacent to the flow path 4. Spilled from the atmosphere and released into the atmosphere. At this time, PM or the like contained in the exhaust gas is collected by the pores formed in the partition wall 2 and the exhaust gas is purified. If PM trapped in the pores exceeds a certain amount and clogging of the pores occurs, the pressure loss increases, leading to a decrease in engine output, which is not preferable. For this reason, the function as a filter is temporarily stopped, and particulates collected by a burner or an electric heater are burned to regenerate the filter.

  On the other hand, Patent Document 1 (Japanese Patent Laid-Open No. 2004-19498) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-251266) are intended to facilitate the regeneration of the ceramic honeycomb filter 40 described above or to improve the purification performance. As shown in FIG. 4, a ceramic honeycomb filter 50 is proposed in which the inflow side sealing portion 5 is disposed away from the inflow side end surface 7 of the honeycomb structure (1). According to the ceramic honeycomb filter 50 shown in FIG. 4, the PM deposited on the upstream end face 5a of the sealing portion 5 is easily burned, and blockage of the flow paths 3 and 4 due to PM deposition can be prevented. The increase in pressure loss is expected to decrease over the long term.

  And in patent document 1, the proposal of the sealing method for obtaining the ceramic honeycomb filter 50 as shown in FIG. 4 is made. That is, in Patent Document 1, a cordierite composition powder is mixed with a predetermined amount of an organic binder and water to prepare a cream-like paste having a stable shape-retaining property, and then the paste has a predetermined length. A ceramic honeycomb filter sealing method has been proposed in which a paste injector (dispenser) having a pipe is used to alternately fill a position 10 mm from the inflow side end face of the ceramic honeycomb structure one by one.

  Patent Document 2 also proposes a sealing method for obtaining a ceramic honeycomb filter 50 as shown in FIG. That is, in Patent Document 2, a resin mask in which the length of the slurry introduction passage is adjusted in accordance with the distance from the inflow side end surface 7 to the sealing portion 5 is provided on the inflow side end surface 7 of the ceramic honeycomb structure (1). As a sealing method in which the slurry is inserted and injected into the flow path through the slurry introduction passage, or as another method, a syringe-like tube is inserted to a predetermined position in the flow path, and a predetermined amount of paste is inserted into the predetermined position through the tube. A method of introducing a sealing material in the form of a material has been proposed.

Japanese Patent Laid-Open No. 2004-19498 JP 2004-251266 A

  However, when injecting cream-like paste with a paste injector (dispenser) proposed in Patent Document 1, or as another method proposed in Patent Document 2, an injection needle-shaped tube is used as a predetermined channel. When a predetermined amount of paste-like sealing material is introduced to a predetermined position through this tube and inserted into the position, there are the following problems. A nozzle 62 such as a paste injector (dispenser) or a needle-like tube is configured at the lower end of a cylinder 61 filled with slurry S pressurized with pressurized air, for example, as shown in FIG. As the needle 63 moves up and down, the valve portion 64 is opened and closed to inject a predetermined amount of slurry. However, even when the injection of a predetermined amount of slurry is completed, the needle 63 descends and the valve portion 64 is closed, the slurry remaining in the nozzle 62 such as a paste injector (dispenser) or a needle-like tube, In order to continue to leak from the tip of a nozzle such as a paste injector (dispenser) or a syringe needle tube, when the syringe needle tube is pulled out from the flow path, the leaked slurry is sealed from the inflow side end surface 7 in FIG. It may adhere to the partition wall 2 in the flow path between the portions 5. In such a case, a part of the flow paths 3 and 4 is blocked by the leaked slurry, the flow path through which the exhaust gas flows is narrowed, and the pressure loss increases when used as the ceramic honeycomb filter 50. was there.

  Accordingly, an object of the present invention is to provide a method for sealing a ceramic honeycomb filter in which the sealing portion is arranged away from the end face of the ceramic honeycomb structure, and the slurry serving as the sealing portion is sealed from the end face of the ceramic honeycomb structure. The flow path is blocked by adhering to the partition wall up to the stop portion, and the flow path through which the exhaust gas flows is not narrowed, and when used as a ceramic honeycomb filter, pressure loss can be prevented from increasing. Another object is to obtain a method for sealing a ceramic honeycomb filter.

  In order to solve the above problems, the present invention provides a sealing method for a ceramic honeycomb filter in which a sealing portion is disposed away from an end face of a ceramic honeycomb structure, and (a) a space formed by a cylinder and a plunger; A step of inserting a tip of a communicating nozzle into a predetermined flow path of the ceramic honeycomb structure; and (b) a slurry that becomes the sealing portion housed in the space by advancing the plunger. Injecting into the flow path of the ceramic honeycomb structure from the tip of the nozzle; and (c) after the injecting step, retracting the plunger to bring the inside of the nozzle to a pressure lower than atmospheric pressure. It is characterized by.

  In the step (a), after determining the mutual position of the nozzle and each flow path of the ceramic honeycomb structure by image analysis or the like, the tip of the nozzle communicating with the space formed by the cylinder and the plunger is It is inserted into a predetermined flow path of the ceramic honeycomb structure. Here, the space formed by the cylinder and the plunger is, for example, between the end surface of the plunger 25 on the inner diameter side of the cylinder 24 as shown in FIG. The part 27 formed by is said. Further, it is preferable that the stroke of the plunger can be appropriately changed according to the amount of slurry to be injected. Further, in order to prevent the nozzle and the ceramic honeycomb structure from being damaged, and to facilitate insertion into the flow path, the nozzle is formed with a taper at the tip and an R at the corner of the tip. preferable.

  In the step (b), the plunger is advanced, and the slurry serving as the sealing portion accommodated in the space is injected into the flow path of the ceramic honeycomb structure from the tip of the nozzle. In addition, if a plurality of nozzles inserted into the channels of the ceramic honeycomb structure are used corresponding to the pitch of the channels, a plurality of sealing portions can be formed simultaneously by one injection.

  In the step (c), after a predetermined amount of slurry is injected into the flow path, the plunger is retracted so that the pressure in the nozzle is lower than the atmospheric pressure, and at least the slurry remaining at the tip of the nozzle is sucked up. So that no slurry remains.

  By the above sealing method, the slurry as the material of the sealing portion adheres to the partition wall from the inflow side end surface of the ceramic honeycomb structure to the sealing portion, the flow path is blocked, and the exhaust gas flows. The flow path is not narrowed, and when used as a ceramic honeycomb filter, an increase in pressure loss can be prevented.

  In the method for sealing a ceramic honeycomb filter of the present invention, the slurry serving as the sealing portion preferably contains an aggregation inhibitor in addition to the ceramic raw material and the liquid component. It is preferable that 70 mass parts and 0.01-10 mass parts of aggregation inhibitors are included.

  The ceramic raw material is preferably made of ceramic particles whose main crystal is the same as that of the honeycomb structure. This makes the thermal expansion coefficient almost equal, reduces the occurrence of cracks due to thermal cycling, and makes the honeycomb filter excellent in durability. be able to. The ceramic raw material has a maximum particle size of 85% or less, preferably 70% or less of the inner diameter of the nozzle, and an average particle size of 1 μm or more, preferably 2 μm or more. If the maximum particle size of the ceramic raw material is smaller than the inner diameter of the nozzle, it will not clog in the nozzle, but actually, if the maximum particle size of the ceramic raw material is slightly smaller than the diameter of the nozzle, it will clog and seal the sealing part. Cannot be formed. For this reason, the maximum particle size of the ceramic raw material is preferably 85% or less, more preferably 70% or less of the nozzle inner diameter. On the other hand, if the particle size of the ceramic raw material is too small, the specific surface area increases and a large amount of liquid component is required for imparting fluidity, and shrinkage increases when the slurry is dried, and sink marks are likely to occur. For this reason, the average particle size of the ceramic raw material needs to be 1 μm or more, preferably 2 μm or more.

  The liquid component is added to provide fluidity by interposing between the ceramic raw materials. After injecting the slurry into the flow path, it moves into the pores of the partition wall by capillary action, or the sealing part is dried. It evaporates in the process and disappears. Therefore, fluidity can be imparted to the ceramic raw material, and a liquid that evaporates at an appropriate temperature, such as water, alcohol, glycerin, etc., may be used, and water is particularly preferred because of its low cost. And it makes it difficult to give fluidity to a ceramic raw material that the liquid component is 10 to 70 parts by weight with respect to 100 parts by weight of the ceramic raw material as described above if the liquid component is less than 10% by weight. On the other hand, if the liquid component exceeds 70% by mass, the slurry may adhere to the partition walls or the opening of the flow path at the time of sealing, and the pressure loss of the honeycomb filter may increase. Further, there is a case where shrinkage is increased when the slurry is dried and sink marks are generated. Therefore, the liquid component is preferably 10 to 70 parts by mass, and more preferably 20 to 60% by mass with respect to 100 parts by mass of the ceramic raw material.

  The anti-agglomeration agent makes it difficult to agglomerate ceramic raw materials to form a uniform structure sealing portion, and also prevents the occurrence of sink marks by making it difficult for the ceramic raw material to move due to the movement of the liquid component. Specific examples include soda ash, water glass, polyacrylate, and polycarboxylate. In addition, when the aggregation inhibitor is used in an amount of 0.01 to 10 parts by mass with respect to 100 parts by mass of the ceramic raw material, the viscosity of the slurry may increase and fluidity may not be imparted even if the amount is too much or too little. Because there is. The aggregation inhibitor is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the ceramic raw material.

  In the ceramic honeycomb filter obtained by the sealing method of the present invention, the length of the sealing portions 5 and 6 on the exhaust gas inflow side and the exhaust gas outflow side in FIG. 4 is preferably 5 to 20 mm. The length of the sealing portions 5 and 6 is set to 5 mm or more. If the length is less than 5 mm, the bonding force between the sealing portions 5 and 6 and the partition wall 2 is reduced, and the sealing portion may fall off due to mechanical vibration or the like. Because. On the other hand, the length of the sealing portions 5 and 6 is set to 20 mm or less. If the length exceeds 20 mm, the thermal shock stress due to the thermal expansion difference or temperature difference between the sealing portions 5 and 6 and the partition wall 2 is increased, and the sealing portion is sealed. This is because a crack may easily enter the boundary between the stoppers 5 and 6 and the partition wall 2.

  The ceramic honeycomb structure constituting the ceramic honeycomb filter obtained by the sealing method of the present invention preferably uses a material having excellent heat resistance, such as cordierite, alumina, mullite, zirconia, sialon, silicon nitride, aluminum nitride. It is preferable to use a ceramic material whose main crystal is at least one selected from the group consisting of silicon carbide, aluminum titanate, and lithium aluminum silicate. Among them, a material having cordierite as the main crystal is most preferable because it is inexpensive, excellent in heat resistance and corrosion resistance, and has low thermal expansion.

  In the sealing method of the ceramic honeycomb filter in which the sealing portion of the present invention is arranged apart from the end face of the ceramic honeycomb structure, the slurry that becomes the sealing portion is between the end face of the ceramic honeycomb structure and the sealing portion. The flow path is blocked by adhering to the partition walls, and the flow path through which the exhaust gas flows is not narrowed, and when used as a ceramic honeycomb filter, an increase in pressure loss can be prevented.

  Hereinafter, as one embodiment of the present invention, a method for sealing the ceramic honeycomb filter 50 shown in FIG. 4 will be described. The ceramic honeycomb filter 50 shown in FIG. 4 is made of cordierite, has an outer diameter of 267 mm, an overall length L of 300 mm, a partition wall 2 of thickness 0.3 mm, a pitch of 1.57 mm, and a porosity. Is 65% and the average pore diameter is 20 μm. And the inflow side end surface 5a of the inflow side sealing part 5 is plugged from the inflow side end surface 7 to the position of the section L1 (120 mm) which is 0.4 times the total length L300 mm of the honeycomb structure (1). .

  FIG. 1 is a schematic cross-sectional view of the sealing device 10 for the ceramic honeycomb filter 50 shown in FIG. FIG. 2 is a schematic diagram showing a sealing process using the sealing device 10 of FIG. A sealing device 10 shown in FIG. 1 includes a moving table (not shown) with an XY stage on which a ceramic honeycomb structure (1) can be placed and soft chucked. On the honeycomb structure (1), slurry injection means 20 is provided. The slurry injection means 20 includes a piston 22 that can be moved up and down in the cylinder 21 by supplying compressed air (Pu, Pd), and a plunger 25 that is connected to the piston 22 by a rod 23 and driven in the cylinder 24. The nozzle 26 is provided so as to protrude below the cylinder 24 and communicates with the cylinder 24, and a space 27 formed between the raising and lowering of the plunger 25. The slurry injection means 20 is separated from the inflow side end face 7 of the ceramic honeycomb structure (1) by the separate pneumatic cylinder (not shown) and the flow path 3 of the ceramic honeycomb structure (1). It is possible to move up (U) and down (D) between the sealing positions.

  Further, a pipe line 38 is connected to the space 27 of the slurry injection means 20, and a valve 39 and a slurry supply means 30 are connected to the pipe line 38. The slurry supply means 30 includes a container 31 that stores the slurry S, and a rotary displacement screw supply machine 33 that is connected to the container 31 via a pipe line 32. The screw-type feeder 33 is rotatably mounted with a screw-like rotor 35 having a perfect circular cross section in a stator 34 having an oval cross section. A motor 36 is connected to the rotor 35. Then, the electrically controlled motor 36 rotates to drive the rotor 35, and the slurry S is transferred downward through the gap 37 between the stator 34 and the rotor 35, and supplied to the space 27 through the pipe line 38. It has come to be.

Next, the sealing method will be described in more detail with reference to FIG.
(A-1)
First, the valve 39 is opened, compressed air is supplied to the cylinder 21 with the air pressure Pu, and the plunger 25 connected to the piston 22 is raised according to the prescribed amount of slurry S to form a space 27. Then, the inside of the container 31 storing the slurry S is pressurized Ps to such an extent that the slurry S can flow gently from the pipe line 32. Further, the motor 36 of the screw type feeder 33 is operated simultaneously with the pressurization Ps. As a result, the slurry S flowing in from the pipe line 32 is transferred downward through the gap 37 between the stator 34 and the rotor 35, and is supplied to the space 27 through the pipe line 38. After the slurry S is supplied into the space 27, the pressure Ps into the container 31, the operation of the motor 36 of the slurry supply machine 33 is stopped, and the valve 39 is closed. The slurry S is a ceramic raw material, 100 parts by weight of cordierite powder having an average particle size of 16 μm and a maximum particle size of 270 μm, 30 parts by weight of water as a liquid component, and 2 parts of polycarboxylic acid ammonium salt as an aggregation inhibitor. A mass part is added and knead | mixed and produced.

(A-2)
Subsequently, in a state where the slurry S is stored in the space 27, the ceramic honeycomb structure (1) on the moving table with an XY stage (not shown) is moved, and the flow path 3 of the honeycomb structure (1). And the nozzle 26 of the slurry injection means 20 are aligned. Next, the tip 26 a of the nozzle 26 is lowered (D) to a site where the sealing portion of the flow path 3 is formed. The nozzle 26 is in the form of a stainless steel injection needle, the outer diameter is 0.5 mm, the inner diameter is 0.3 mm, the tip is tapered, and an R is formed at the tip.

(B)
Subsequently, compressed air is supplied to the cylinder 21 with the air pressure Pd, and the plunger 25 is slowly lowered to the lower end of the cylinder 24 together with the piston 22, and the slurry S in the space 27 is discharged from the nozzle 26 to the ceramic honeycomb structure (1). Inject into the flow path 3. At this time, the slurry S is injected in a section (L1) in which the inflow side end face 5a of the inflow side sealing portion 5 is 0.4 times the average of the total length (L) 300 mm of the ceramic honeycomb structure 1 from the inflow side end face 7. The position should be 120 mm. Further, the slurry S is uniformly injected into the flow path 3 by reciprocating the nozzle 26 in the direction of the flow path 3. In FIG. 2, the slurry supply means 30 is omitted in the injection step (b) and the wicking step (c).

(C)
After the slurry S is injected into the flow path 3, compressed air is supplied to the cylinder 21 with the air pressure Pu 2 to slightly raise the plunger 25, and the inside of the nozzle 26 together with the space 27 is set to a pressure lower than the atmospheric pressure. The slurry S is sucked up so that no slurry S drops on the tip 26a of the nozzle 26.

  Subsequently, although not shown in FIG. 2, the slurry injection means 20 in FIG. 1 is raised (U), the tip 26a of the nozzle 26 is retracted from the inflow side end face 7 of the ceramic honeycomb structure (1), and then X -The ceramic honeycomb structure (1) on the Y stage is moved (not shown), the next flow path 3 is positioned, and (a-1) to (c) are repeated.

  As described above, the slurry S serving as the sealing portion adheres to the partition wall 2 between the ceramic honeycomb structure (1) inflow side end surface 7 and the sealing portion 5 to block the flow path, and the exhaust gas flows. A ceramic honeycomb filter can be obtained in which the flow path is not narrowed and pressure loss can be prevented from increasing when used as a ceramic honeycomb filter (50).

  On the other hand, although not explained in FIGS. 1 and 2, the sealing portion 6 on the outflow side in FIG. 4 is obtained by aligning the resin sealing film attached to the outflow side end surface 8 with the flow path 3 with a laser. The checkerboard pattern is perforated, the outflow side end face 8 is immersed in the slurry as the material of the sealing portion 6, the slurry is filled into the flow path 3 through the perforation, and then the sealing film is removed. Dry. Subsequently, the end surfaces 5a of the inflow-side sealing portions 5 have a total length (L) from the inflow-side end surface 7 by firing the sealing portions 5 and 6 while controlling the temperature using a batch-type firing furnace. The ceramic honeycomb filter 50 is disposed in the section (L1) 120 mm which is 0.4 times.

Examples will be described below.
(Example 1)
The inflow side end face 7 and the outflow of the cordierite ceramic honeycomb structure (1) having an outer diameter of 320 mm, an overall length of 300 mm, a partition wall thickness of 0.3 mm, a partition wall pitch of 1.57 mm, and a porosity of 65%. The side end face 8 was ground. On the other hand, the slurry used as the material of the sealing part 5 was prepared by adding and mixing water as a liquid component and soda ash as an anti-aggregation agent to cordierite powder and adjusting the viscosity to 9 Pa · s. Next, the sealing portion 5 shown in FIG. 4 was formed by the sealing method according to the above-described embodiment, and Example 1 was obtained. That is, in FIG. 2 (a-2), the tip 26a of the nozzle 26 is inserted into a position 120 mm from the end face 7 of the honeycomb structure (1), and the pressure Pd is applied to the cylinder 21 as shown in FIG. 2 (b). The plunger 25 was moved down together with the piston 22 to cause the slurry S to be injected into the flow path from the nozzle. After completion of the injection, as shown in FIG. 2 (c), 50% pressure Pu2 at the time of injection is applied to the cylinder 21 to make the inside of the nozzle 26 lower than the atmospheric pressure, and the slurry S in the nozzle 26 is dripped. I tried not to.
In the sealing method of Example 1, since the slurry serving as the sealing portion did not adhere to the partition walls 2 from the inflow side end surface 7 of the ceramic honeycomb structure (1) to the sealing portion 5, It was found that the passage of exhaust gas was not narrowed without blocking the passage, and the pressure loss when the ceramic honeycomb filter 50 was used was prevented from increasing.

(Comparative Example 1)
On the other hand, as Comparative Example 1, a cordierite ceramic honeycomb structure and slurry similar to Example 1 were used except that the slurry injection means shown in FIG. 5 was used for slurry injection. That is, the tip of the nozzle 62 is inserted at a position 120 mm from the end face of the honeycomb structure (1), and as shown in FIG. 5, the needle 63 is raised to open the valve portion 64, and the slurry S flows from the nozzle. Injected into the tract. After the injection was completed, the needle 63 was lowered and the valve part 64 was closed. And the nozzle 62 was pulled out from the flow path, the nozzle was moved to the flow path which performs sealing next, and sealing was performed similarly.
In Comparative Example 1, when the nozzle 62 is pulled out from the flow path, the slurry adheres to the partition wall 2 between the inflow side end surface 7 of the honeycomb structure (1) and the sealing portion 5 to block the flow path. As a result, the flow path through which the exhaust gas flows was narrowed. From this, it was found that when used as the ceramic honeycomb filter 50, the pressure loss may increase.

It is a cross-sectional schematic diagram of the sealing device used for the sealing method of the ceramic honeycomb filter of embodiment. It is a schematic diagram which shows the sealing process using the sealing device of FIG. It is a cross-sectional schematic diagram of a conventional ceramic honeycomb filter that collects and purifies PM in automobile exhaust gas. FIG. 3 is a schematic cross-sectional view of a ceramic honeycomb filter proposed in Patent Document 2. It is the figure which showed the prior art.

Explanation of symbols

1: Outer wall (1): Ceramic honeycomb structure 2: Partition wall 3, 4: Channel 5: Inflow side sealing portion 6: Outflow side sealing portion 5a: Inflow side end surface of the inflow side sealing portion 5L: Inflow side Length of sealing part 7: Inflow side end surface 8: Outflow side end surface 10: Sealing device 20: Slurry injection means 21: Cylinder 22: Piston 23: Rod 24: Cylinder 25: Plunger 26: Nozzle 26a: Nozzle tip 27 : Space 30: Slurry supply means 31: Container for storing slurry 32: Pipe line 33: Screw-type feeder 34: Stator 35: Rotor 36: Motor 37: Gap 38: Pipe line 39: Valve 40, 50: Ceramic honeycomb filter 60: Conventional slurry injection means 61: Cylinder 62: Nozzle 63: Needle 64: Valve part L: Full length L1: Position of the exhaust gas inflow side sealing part Ps: Pressurization (in a container for storing slurry)
Pd, Pu, Pu2: Air pressure (compressed air)
S: Slurry

Claims (1)

A sealing method of a ceramic honeycomb filter in which a sealing portion is arranged apart from an end face of a ceramic honeycomb structure, wherein (a) a tip of a nozzle communicating with a space formed by a cylinder and a plunger is connected to the ceramic honeycomb A step of inserting the structure into a predetermined flow path; and (b) advancing the plunger to move the slurry serving as the sealing portion accommodated in the space from the tip of the nozzle to the ceramic honeycomb structure. Sealing the ceramic honeycomb filter, comprising: injecting into the flow path; and (c) after the injecting step, the plunger is retracted to bring the inside of the nozzle to a pressure lower than atmospheric pressure. Method.

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