JP4916405B2 - Manufacturing method of honeycomb structure - Google Patents

Description

  The present invention relates to a method for manufacturing a honeycomb structure. Specifically, the present invention relates to a process for extruding a honeycomb structure.

  In various fields including chemical, electric power, steel, and industrial waste treatment, honeycomb structures made of ceramics having excellent heat resistance, corrosion resistance, and mechanical strength are used. This honeycomb structure is used, for example, as a filter for dust collection and water treatment used for environmental measures such as pollution prevention, product recovery from high-temperature gas, or as a catalyst carrier. It is suitably used as a diesel particulate filter (DPF) that collects particulates (soot) contained in exhaust gas from an engine or the like and a catalyst carrier for exhaust gas treatment.

The honeycomb structure has, for example, a plurality of through holes (cells 3) serving as fluid flow paths partitioned by the porous partition walls 2 as in the honeycomb structure 1 shown in FIG. carries a catalyst for decomposing HC or NO _x are used as a catalyst for purifying exhaust gases above.

  Further, as shown in FIG. 2 and FIG. 3, a structure in which the cells 3 of the honeycomb structure 1 are sealed at different positions at both end surfaces where the cells 3 are opened, and exhaust gas is allowed to flow into each cell 3 opened at one end surface. A filter (honeycomb filter) that collects and removes particulate matter in the exhaust gas by forcibly passing through the porous partition walls 2 has been developed.

  Usually, a kneaded material obtained by mixing and kneading molding raw materials including ceramic raw material powder is extruded by extrusion from a die having a shape complementary to the partition wall pattern of the honeycomb structure, and the molded body. It is manufactured by baking.

  In the manufacturing method as described above, if coarse particles or foreign substances are present in the ceramic raw material powder, the resulting molded body (particularly, the partition wall) may be defective or the extrusion die may be damaged. There is. In particular, in recent years, for the purpose of reducing the pressure loss of exhaust gas, etc., the wall thickness of the partition walls of the honeycomb structure has been rapidly reduced, and the occurrence of defects in the structure partition walls is becoming a very serious problem.

  Therefore, in order to prevent the above-described problems, for example, a method for manufacturing a honeycomb formed body is disclosed in which the clay is passed through a screen having a predetermined mesh and then extruded from the die (for example, Patent Documents). 1).

WO05 / 018893 pamphlet

  Although the above method is a method that can effectively prevent the occurrence of defects in the molded body and the breakage of the die, even if continuous molding is performed, the extruder is caused by clogging of the screen that occurs over time. There was a problem that the load applied to the gradual increase. That is, it is necessary to periodically stop the extruder and replace the screen, and there remains a problem to be solved in that the productivity is reduced by this replacement operation.

  For such problems, ceramic raw material powder is sieved in advance to remove coarse particles and foreign matters, but even if such sieving is performed, the screen is still clogged sufficiently. It has not been suppressed and has not yet been resolved.

  Thus, at present, no method has been disclosed that can effectively prevent the occurrence of defects in the molded body and the breakage of the die without reducing the productivity. The present invention has been made in view of the problems of the prior art as described above, and can be used to manufacture a honeycomb structure that can effectively prevent generation of defects in a molded body and breakage of a die without reducing productivity. A method is provided.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have surprisingly found that the above-mentioned problems can be solved by adding a predetermined treatment to the cellulose-based binder contained in the forming raw material, The present invention has been completed. That is, the present invention provides the following method for manufacturing a honeycomb structure.

[1] A mixing / kneading step of obtaining a kneaded material by mixing and kneading a forming raw material containing ceramic raw material powder, a cellulose-based binder and a dispersion medium, and the kneaded material in a shape complementary to the partition wall pattern of the honeycomb structure An extrusion forming step of obtaining a honeycomb formed body having partition walls for partitioning and forming cells serving as fluid flow paths by extruding from a die formed with a slit, and firing the honeycomb formed body to obtain a honeycomb structure. And a firing step for obtaining a honeycomb structure, wherein the ceramic raw material powder has a coarse particle ratio of 20 mass ppm or less with a particle size of 90% or more of the slit width of the die When a 0.1% by mass aqueous solution is prepared as the cellulose-based binder, it is insoluble in water, and its fiber length is the slip of the die. The undissolved fiber content of 35% or more of the width is 1000 pieces / 2 ml or less, and the clay is passed through a screen having an opening of 75 to 170% of the slit width of the base. A method for manufacturing a honeycomb structure extruded from a honeycomb structure.

[2] As the cellulosic binder, an undissolved fiber content of 200 pieces / insoluble in water when a 0.1% by mass aqueous solution is prepared and whose fiber length is 35% or more of the slit width of the die The method for manufacturing a honeycomb structured body according to the above [1], wherein 2 ml or less is used.

[3] The method for manufacturing a honeycomb structured body according to [1] or [2], wherein the die having a slit width of 45 to 110 μm is used.

[4] The honeycomb structure according to any one of [1] to [3], wherein a material obtained by adding 3 to 8 parts by mass of the cellulose binder to 100 parts by mass of the ceramic raw material powder is used as the forming raw material. Manufacturing method.

[5] The method for manufacturing a honeycomb structure according to any one of [1] to [4], wherein a cordierite forming raw material is used as the ceramic raw material powder.

[6] As the cordierite forming raw material, talc powder having an average particle diameter of 3 to 25 μm, kaolin powder and / or calcined kaolin powder having an average particle diameter of 1 to 15 μm, alumina having an average particle diameter of 0.5 to 10 μm The powder and / or aluminum hydroxide powder, the one obtained by mixing powder selected from the group of boehmite powder having an average particle diameter of 0.05 to 1 μm and silica powder having an average particle diameter of 1 to 10 μm is used. The manufacturing method of the honeycomb structure according to any one of [1] to [5].

[7] A sieve having an opening corresponding to 60 to 170% of the slit width of the die for kaolin powder, calcined kaolin powder, alumina powder, aluminum hydroxide powder, boehmite powder and silica powder in the cordierite forming raw material The method for manufacturing a honeycomb structure according to any one of [1] to [6], wherein a sieve that is passed through and sieved is used.

  The method for manufacturing a honeycomb structured body of the present invention can effectively prevent the occurrence of defects in the molded body and the breakage of the die without reducing the productivity.

  Hereinafter, the best mode for carrying out the method for manufacturing a honeycomb structured body of the present invention will be specifically described. However, the present invention broadly encompasses manufacturing methods having the invention-specific matters, and is not limited to the following embodiments.

[1] Production method of the present invention:
The method for manufacturing a honeycomb structure of the present invention includes a mixing and kneading step of obtaining a kneaded material by mixing and kneading a forming raw material containing ceramic raw material powder, a cellulose-based binder and a dispersion medium, and the kneaded material is mixed with the kneaded material. An extrusion forming step of obtaining a honeycomb formed body having partition walls for partitioning and forming cells serving as fluid flow paths by extruding from a die formed with a slit having a shape complementary to the partition wall pattern of A firing step of obtaining a honeycomb structure by firing, and the ceramic raw material powder having a grain size of 90% or more of the slit width of the die and a ratio of coarse particles of 20 mass ppm or less is used. The cellulose-based binder is insoluble in water when a 0.1% by mass aqueous solution is prepared, and the fiber length is the slit width of the die. Using insoluble fiber content which is 5% or more of the following 1000/2 ml, was passed through a 75 to 170% of the mesh screens of the slit width of the die, in which extruded from the spinneret.

[1-1] Mixing / kneading step:
The first step of the production method of the present invention is a mixing / kneading step in which a clay is obtained by mixing and kneading a forming raw material containing ceramic raw material powder, a cellulose binder and a dispersion medium.

[1-1A] Ceramic raw material powder:
The “forming raw material” in the production method of the present invention includes at least a ceramic raw material powder, a cellulose-based binder, and a dispersion medium. The “ceramic raw material powder” is a ceramic powder constituting the honeycomb structure. Examples thereof include ceramic powders such as mullite, alumina, aluminum titanate, lithium aluminum silicate, silicon carbide, and silicon nitride.

In addition, the “ceramic raw material powder” includes a powder of a material that is a raw material of the ceramic constituting the honeycomb structure. For example, talc, kaolin, calcined kaolin, alumina, aluminum hydroxide, boehmite, silica, etc. mixed so that the composition after firing becomes the theoretical composition of cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ) Baked at 1400 to 1450 ° C., 95% or more of the crystal phase is converted to cordierite. Therefore, powders of these substances (cordierite raw materials) are also included in the “ceramic raw material powder”. In the production method of the present invention, since the coefficient of thermal expansion can be reduced by orienting the cordierite crystals in the direction of the extrusion flow path due to the flat particle shape of the talc and kaolin raw materials, It is preferable to use a lightening raw material.

  In the production method of the present invention, as the “ceramic raw material powder”, it is necessary to use a powder whose particle diameter is 90% or more of the slit width of the extrusion die and whose coarse particle ratio is 20 mass ppm or less. . By using the ceramic raw material powder having such a particle size distribution, along with the control of the fiber content of the cellulose-based binder described later, it is possible to suppress clogging of the screen that occurs over time. It becomes possible to reduce the frequency of stopping and replacing the screen. That is, it contributes to productivity improvement. On the other hand, when the ratio of the coarse particles exceeds 20 mass ppm, there is a possibility that problems such as clogging of the screen cannot be suppressed even if the undissolved fiber content of the cellulose binder described later is controlled.

  The “particle size” referred to in the present specification was measured by a laser diffraction / scattering particle size measuring device (for example, trade name “LA-910” (manufactured by Horiba, Ltd.)) based on the light scattering method. Means particle size. The ratio of the particles can also be measured by this measurement method. In addition, “average particle diameter” described later means a value of 50% particle diameter calculated by this measurement method.

  In the production method of the present invention, when a cordierite-forming raw material is used as the ceramic powder, talc powder having an average particle diameter of 3 to 25 μm, kaolin powder and / or calcined kaolin powder having an average particle diameter of 1 to 15 μm, average A powder selected from the group consisting of alumina powder and / or aluminum hydroxide powder having a particle size of 0.5 to 10 μm, boehmite powder having an average particle size of 0.05 to 1 μm, and silica powder having an average particle size of 1 to 10 μm. It is preferable to use what is obtained by mixing.

  In the production method of the present invention, from the viewpoint of suppressing clogging of the screen that occurs over time, it is preferable to remove coarse particles and foreign matters from the ceramic raw material powder by sieving. As the cordierite forming raw material, a material obtained by passing through a sieve having an opening corresponding to 60 to 170% of the slit width of the die is used. However, as for talc, it is preferable to use a talc that has been sieved by passing through a sieve having an opening corresponding to 60 to 140% of the slit width of the die.

[1-1B] Cellulosic binder:
The cellulose-based binder is an additive that functions as a reinforcing agent that imparts fluidity to the kneaded clay and maintains the mechanical strength of the honeycomb formed body before firing in the forming step described later. As the cellulose-based binder, at least from the group of methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxybutylcellulose, hydroxyethylmethylcellulose and hydroxypropylmethylcellulose from the shape retention during molding and drying and the gelation strength during firing. One type is preferably selected and used according to desired process conditions.

  The amount of the cellulose-based binder in the forming raw material is preferably 3 to 8 parts by mass, and more preferably 4 to 6 parts by mass with respect to 100 parts by mass of the ceramic raw material powder. By setting the amount of the cellulose binder to 3 parts by mass or more, an effect of improving the strength of the extruded product can be obtained. On the other hand, when the amount of the cellulose-based binder is 8 parts by mass or less, an effect of reducing the occurrence of burnout in the debinding temperature region during baking can be obtained.

  In the production method of the present invention, as the cellulose-based binder, an undissolved fiber which is insoluble in water when a 0.1% by mass aqueous solution is prepared and whose fiber length is 35% or more of the slit width of the die It is necessary to use one having a minute of 1000 pieces / 2 ml or less, and preferably using 200 pieces / 2 ml or less.

  By controlling the amount of such fibers to a predetermined level or less, screen clogging that occurs over time can be suppressed. Therefore, it becomes possible to stop the extrusion molding machine and reduce the frequency of replacing the screen, which contributes to the improvement of the productivity of the honeycomb structure. That is, the production method of the present invention has been found that the fiber contained in the cellulosic binder, rather than the coarse particles and foreign matter of the ceramic raw material powder, causes clogging of the screen.

  The number of undissolved fibers is measured by a method using a trade name: Coulter Counter (manufactured by Coulter, Inc.) disclosed in JP-A No. 2004-26861. An aqueous electrolyte solution for a coulter counter (trade name: ISOTON II, manufactured by Coulter Co.) is used as a solvent, and a cellulose binder is dissolved in the solvent to prepare a 0.1% by mass aqueous solution of the cellulose binder.

  However, since the cellulose binder only dissolves under low temperature conditions, after dispersing the cellulose binder in the solvent under a temperature condition of 80 to 90 ° C, methylcellulose is 5 ° C, and other cellulose binders are 25 ° C. Cool in a thermostat and dissolve. Thereafter, the temperature is set to 25 ° C., and the number of undissolved fibers whose fiber length is 35% or more of the slit width of the die is measured by a Coulter counter.

[1-1C] Dispersion medium:
In the production method of the present invention, water is generally used as a dispersion medium for dispersing ceramic raw material powder, cellulose binder, and the like. However, it may contain other solvents such as alcohol. The amount of the dispersion medium is preferably 20 to 75 parts by mass, and more preferably 25 to 40 parts by mass with respect to 100 parts by mass of the ceramic raw material powder.

[1-1D] Other additives:
As described above, the “forming raw material” in the production method of the present invention includes at least a ceramic raw material powder, a cellulose-based binder, and a dispersion medium. However, the “forming raw material” may contain other additives as necessary. Examples of the other additive include a pore former for adjusting the porosity of the honeycomb structure, a dispersant for obtaining a homogeneous clay, and a binder other than the cellulose-based binder.

  More specifically, pore-forming materials such as graphite, wheat flour, starch, phenol resin, polymethyl methacrylate, polyethylene, or polyethylene terephthalate, acrylic resin microcapsules; interfaces of ethylene glycol, dextrin, fatty acid soap, polyalcohol, etc. An activator; a binder such as polyvinyl alcohol; and the like may be appropriately selected and contained.

[1-1E] Mixing / kneading:
In the production method of the present invention, the clay is obtained by mixing and kneading the forming raw materials. The mixing / kneading method is not particularly limited, and mixing and kneading can be performed using a conventionally known mixer or kneader.

  Examples of the mixer include a sigma kneader and a ribbon mixer. However, a mixer that can be stirred while applying a shearing force to the forming raw material, such as a plow shear mixer (trade name: plow shear mixer, manufactured by Taiheiyo Kiko Co., Ltd.), a Henschel mixer (trade name: Mitsui Henschel mixer, Mitsui Mining Co., Ltd., etc.) can be suitably used. These mixers are preferable in that they have a high effect of pulverizing agglomerates of ceramic raw material powder formed in the forming raw material.

  Examples of the kneader include a sigma kneader, a Banbury mixer, and a screw type extrusion kneader. In particular, if a kneading machine (so-called vacuum kneader) equipped with a vacuum decompression device (for example, a vacuum pump) for degassing the air contained in the molding compound (and thus the clay) is used, defects will be caused. This is preferable in that a clay with good moldability can be obtained.

  Also, as the kneading machine, by using a continuous kneading molding machine that supplies the powder passed through the mixer at a constant supply amount and continuously extrudes the kneaded clay to the base while kneading with a screw, The molding can be continued and it is efficient. This method is preferable particularly when forming with a die having a thin slit width because it is not necessary to pay attention to cell deformation when supplying clay to the extrusion molding machine. Also in the manufacturing method of this invention, it is preferable to mix with a pro shear mixer and shape | mold with the continuous kneading extrusion molding machine provided with the vacuum pressure reduction apparatus.

[1-2] Extrusion molding process:
In the second step of the manufacturing method of the present invention, the clay is extruded from a die formed with a slit having a shape complementary to the partition wall pattern of the honeycomb structure, thereby forming a cell serving as a fluid flow path. This is an extrusion molding step for obtaining a honeycomb formed body provided with partition walls.

[1-2A] Base:
The die used in the manufacturing method of the present invention is formed with slits having a shape complementary to the partition wall pattern of the honeycomb structure. For example, the honeycomb structure 1 shown in FIG. 2 has a large number of quadrangular cells 3 and the partition walls 4 are arranged in a lattice pattern. When manufacturing such a honeycomb structure, an extruded body can be obtained by extruding clay from a die having slits having a shape complementary to the lattice pattern. With this method, a honeycomb structure formed body having a desired cell shape, partition wall thickness, and cell density can be easily obtained.

  In the production method of the present invention, the base having a slit width of 45 to 110 μm can be used in accordance with the use of a desired product. The thinner the slit width, the more easily affected by coarse particles and foreign matters, and the effect of the present invention can be exhibited.

[1-2B] Extruder:
Examples of the extrusion molding machine include a ram type extrusion molding machine and a biaxial continuous molding machine. Among these, a biaxial continuous molding machine is preferable. The biaxial continuous molding machine has an advantage that a uniform molded body can be obtained as compared with other extrusion molding machines.

[1-2C] Screen:
In the production method of the present invention, the clay is extruded from the base after passing through a screen having an opening of 75 to 170% of the slit width of the base. By setting the screen opening to 170% or less of the slit width of the die, coarse particles, foreign matter, fibers, etc. in the forming raw material can be captured by the screen. It is possible to effectively prevent the base from being damaged.

  In addition, by making the screen opening 75% or more of the slit width of the base, clogging of the screen can be suppressed, and this is in combination with controlling the fiber content in the cellulosic binder to a predetermined ratio or less. Thus, the extrusion molding machine is stopped, the frequency of replacing the screen is reduced, and consequently, the productivity is improved. In order to obtain these effects more reliably, it is preferable to pass through a screen having an aperture of 110 to 140% of the slit width of the die and then extrude from the die.

[1-2D] Others:
The honeycomb formed body thus obtained is preferably dried prior to firing. As a drying method, for example, a conventionally known drying method such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, freeze drying or the like can be used. Among these, a drying method in which hot air drying and microwave drying or dielectric drying are combined is preferable in that the entire molded body can be quickly and uniformly dried.

[1-3] Firing step:
The third step of the production method of the present invention is a firing step for obtaining a honeycomb structure by firing the honeycomb formed body.

  Firing means an operation for sintering and densifying the ceramic raw material powder to ensure a predetermined strength. Since the firing conditions (temperature and time) vary depending on the type of ceramic raw material powder constituting them, an appropriate condition may be selected according to the type of ceramic raw material powder used. For example, when using a cordierite forming raw material as a ceramic raw material powder, it is preferably fired at a temperature of 1410 to 1440 ° C. for 2 to 15 hours. If the firing condition (temperature / time) is less than the above range, it is not preferable in that the sintering of the ceramic raw material powder may be insufficient, and if it exceeds the above range, the generated cordierite may be melted. It is not preferable in terms.

  If an operation (calcination) for burning and removing organic substances (binder, pore former, dispersant, etc.) in the honeycomb formed body or the plugging portion is performed before firing or in the temperature raising process of firing, It is preferable because the removal of the water can be further promoted. Since the burning temperature of the binder is about 200 ° C. and the burning temperature of the pore former is about 300 ° C., the calcining temperature may be about 200 to 1000 ° C. The calcining time is not particularly limited, but is usually about 10 to 100 hours.

  In applications such as DPF, as in the honeycomb structure shown in FIGS. 2 and 3, one opening and the other opening of many cells 3 of the honeycomb structure 1 are alternately plugged. The plugging portion 10 is formed. In the honeycomb structure having such a plugged portion 10, when a gas to be treated is introduced into the cell 3 from the inlet side end face 2 a, contaminants such as particulates are trapped in the partition wall 4, while the porous partition wall 4. Since the treated gas that has passed through the gas and flows into the adjacent cell 3 is discharged from the outlet side end face 2b, the treated gas from which the particulates in the gas to be treated have been removed can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  In addition, about the average particle diameter described in the Example shown below and a comparative example, the laser diffraction / scattering type | formula particle size measuring apparatus (for example, brand name "LA-910" (Horiba Seisakusho) which made the light scattering method the measurement principle) The value of the 50% particle diameter measured by

  The number of undissolved fibers was measured using a trade name: Coulter Counter Z2 type (manufactured by Coulter). An aqueous electrolyte solution for a coulter counter (trade name: ISOTON II, manufactured by Coulter Co., Ltd.) was used as a solvent, a cellulose binder was dissolved in this solvent to prepare a 0.1% by mass aqueous solution of the cellulose binder, and 0.5 ml of this aqueous solution was then added. The number of undissolved fibers of 8 μm or more and 60 μm or less present therein was measured four times using an aperture tube having an inner diameter of 100 μm. Four measurement values were integrated to obtain the number of undissolved fibers contained in 2 ml of the aqueous solution. In addition, when the some cellulose binder was used, it mixed and measured according to the ratio which used each binder.

[Manufacture of honeycomb structure]
First, a clay was obtained by mixing and kneading a forming raw material containing ceramic raw material powder, a cellulose-based binder and a dispersion medium. At this time, a cordierite forming raw material was used as the ceramic raw material powder, methylcellulose was used as the cellulose binder, and water was used as the dispersion medium. The raw material specification of the ceramic raw material powder is shown in Table 1, the raw material specification of the cellulose-based binder is shown in Table 2, the blending ratio of the ceramic raw material powder of each Example / Comparative Example is shown in Table 3, and the cellulose-based binder of each Example / Comparative Example Table 4 shows the blending ratio. This compounding ratio is such that the coefficient of thermal expansion (25 to 800 ° C.) in the flow path direction (cell forming direction) is 0.3 × 10 ⁻⁶ / ° C. or lower by firing at a temperature of 1410 to 1440 ° C. for 2 to 15 hours. The average pore diameter is 3 to 8 μm, and the porosity is 25% or more.

  Next, the above-mentioned forming raw materials were mixed with a proshear mixer and formed with a continuous kneading extrusion molding machine equipped with a vacuum decompression device. The supply amount of the mixed powder was 450 kg / hr.

  In the molding, a honeycomb molded body having partition walls for partitioning cells serving as fluid flow paths was obtained by extruding from a die formed with a slit having a shape complementary to the partition wall pattern of the honeycomb structure. At this time, as the continuous kneading extrusion molding machine, a screen was disposed therein, and the openings described in Table 5 and Table 6 were used. As the die, those having slit widths described in Table 5 and Table 6 arranged in a lattice shape were used.

The honeycomb formed body thus obtained was as follows.
(1) Honeycomb compact A:
The shape of the end face (cell opening face) is a circle with an outer diameter of 106 mmφ, the total length (flow path length) is 100 mm, the cell shape is a square cell of 0.85 mm × 0.85 mm, the partition wall thickness is 47 μm, and the cell density is about 900. Cell / square inch honeycomb molded body.
(2) Honeycomb compact B:
The end face (cell opening face) has a circular shape with an outer diameter of 110 mmφ and a full length (flow path length) of 120 mm. The cell shape is a square cell of 1.00 mm × 1.00 mm, the partition wall thickness is 71 μm, and the cell density is about 600. Cell / square inch honeycomb molded body.
(3) Honeycomb compact C:
The shape of the end face (cell opening face) is a circle with an outer diameter of 110 mmφ, the total length (flow path length) is 120 mm, the cell shape is a square cell of 1.10 mm × 1.10 mm, the partition wall thickness is 102 μm, and the cell density is about 400. Cell / square inch honeycomb molded body.

[Evaluation method (overall)]
In the following evaluation of the pressure at 20 t passing and the rate of increase in pressure, when both evaluations were good, “good / ◯” was evaluated, and when either one was bad, “bad / ×” was evaluated. The results are shown in Tables 5 and 6.

[Evaluation method (pressure when passing through 20t)]
The above extrusion molding is continuously performed until the clay passes through 20 t. When the difference between the pressure when the clay passes through 20 t and the initial pressure is 15 bar (1500 kPa) or less, “good / ◯” and 15 bar (1500 kPa) are set. When it exceeded, it evaluated as "defect / x". The results are shown in Tables 5 and 6.

[Evaluation method (pressure increase rate)]
The value of the difference between the 20t passage pressure and the initial pressure was divided by 20 to calculate the rate of pressure increase per 1t passage. When the rate of pressure increase was 0.75 bar / t or less, it was evaluated as “good / ◯”, and when it exceeded 0.75 bar / t, it was evaluated as “bad / ×”. The results are shown in Tables 5 and 6.

[Evaluation results]
As a result of the evaluation by the above method, the honeycomb formed bodies of Examples 1 to 7 were formed as a raw material of ceramic raw material powder having a ratio of the coarse particles of a predetermined value or less and cellulose having an undissolved fiber content of a predetermined value or less. Since a system binder was used, both the pressure when passing through 20 t and the pressure increase rate showed good results. According to these methods, even when continuous molding is performed, the rate of increase in load on the extruder can be kept low due to clogging of the screen that occurs over time, and the extruder is periodically stopped. It was recognized that it was possible to reduce the frequency of changing the screen. That is, it was considered that the method was highly productive.

  On the other hand, the honeycomb molded body of Comparative Example 1 is a ceramic in which the ratio of the coarse particles exceeds 20 ppm by mass even though the cellulose-based binder having an undissolved fiber content of 1000 pieces / 2 ml or less is used as a forming raw material. Since the raw material powder was used, both the pressure when passing through 20t and the rate of pressure increase were poor. In addition, the honeycomb formed bodies of Comparative Examples 2 to 9 were poor in both the pressure when passing through 20 t and the rate of pressure increase because the cellulose-based binder with the undissolved fiber content exceeding 1000 pieces / 2 ml was used as a forming raw material. In these methods, when continuous molding is performed, it is not possible to suppress an increase in load applied to the extruder due to clogging of the screen that occurs over time, and the extruder is periodically stopped to remove the screen. It was recognized that the frequency of replacement would increase. In other words, it was thought that a decrease in productivity could not be avoided.

  Further, as is clear from Comparative Examples 2, 3, 6, 7, and 8, when a cellulose-based binder having an undissolved fiber content of more than 1000/2 ml is used as a forming raw material, Even when a ceramic raw material powder whose ratio was controlled to be less than 20 ppm by mass was used, the pressure at 20t and the rate of pressure increase were poor.

  The method for manufacturing a honeycomb formed body of the present invention adsorbs, absorbs, and decomposes dust collection / water treatment filters such as a diesel particulate filter (DPF) or NOx, CO, and HC in exhaust gas. It is useful as a method for producing a honeycomb structure suitably used as a catalyst carrier for the purpose.

1 is a perspective view schematically showing one embodiment of a honeycomb structure. 1 is a cross-sectional view schematically showing one embodiment of a honeycomb structure. FIG. 3 is a diagram schematically showing an end surface of the honeycomb structure, and is a diagram showing an end surface of the honeycomb structure shown in FIG. 2.

Explanation of symbols

1: honeycomb structure, 2: partition, 2a: inlet side end surface, 2b: outlet side end surface, 3: cell, 4: partition, 10: plugging portion.

Claims (7)

A mixing and kneading step of obtaining a clay by mixing and kneading a molding raw material containing ceramic raw material powder, a cellulose-based binder and a dispersion medium;
Extrusion molding that obtains a honeycomb formed body having partition walls for partitioning cells serving as fluid flow paths by extruding the clay from a die formed with a slit having a shape complementary to the partition wall pattern of the honeycomb structure. Process,
A firing step of obtaining a honeycomb structure by firing the honeycomb formed body,
A method for manufacturing a honeycomb structure comprising:
As the ceramic raw material powder, the ratio of coarse particles whose particle size is 90% or more of the slit width of the die is 20 mass ppm or less,
When the 0.1% by mass aqueous solution is prepared as the cellulose-based binder, the undissolved fiber content is insoluble in water, and the fiber length is 35% or more of the slit width of the die, which is 1000 pieces / 2 ml or less. Use things
A method for manufacturing a honeycomb structure, wherein the clay is extruded from the die after passing through a screen having an opening of 75 to 170% of the slit width of the die.   As the cellulose-based binder, when 0.1% by mass aqueous solution is prepared, the amount of undissolved fibers that are insoluble in water and whose fiber length is 35% or more of the slit width of the die is 200 pieces / 2 ml or less. The method for manufacturing a honeycomb structured body according to claim 1, wherein one is used.   The method for manufacturing a honeycomb structure according to claim 1 or 2, wherein the die has a slit width of 45 to 110 µm.   The method for manufacturing a honeycomb structured body according to any one of claims 1 to 3, wherein a material obtained by adding 3 to 8 parts by mass of the cellulose-based binder to 100 parts by mass of the ceramic raw material powder is used as the forming raw material.   The method for manufacturing a honeycomb structured body according to any one of claims 1 to 4, wherein a cordierite forming raw material is used as the ceramic raw material powder.   As the cordierite forming raw material, talc powder having an average particle diameter of 3 to 25 μm, kaolin powder and / or calcined kaolin powder having an average particle diameter of 1 to 15 μm, alumina powder having an average particle diameter of 0.5 to 10 μm, and / or Alternatively, aluminum hydroxide powder, boehmite powder having an average particle diameter of 0.05 to 1 μm, or powder obtained by mixing powder selected from the group of silica powder having an average particle diameter of 1 to 10 μm is used. A method for manufacturing a honeycomb structured body according to any one of the above.   In the cordierite forming raw material, kaolin powder, calcined kaolin powder, alumina powder, aluminum hydroxide powder, boehmite powder and silica powder are passed through a sieve having an opening corresponding to 60 to 170% of the slit width of the die. The method for manufacturing a honeycomb structured body according to any one of claims 1 to 6, wherein a sieved product is used.

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