JP5854729B2 - Method for manufacturing ceramic fired body and method for manufacturing honeycomb structure - Google Patents

Description

The present invention relates to the production how the manufacturing process and the honeycomb structure fired ceramics body.

  2. Description of the Related Art Conventionally, an SCR (Selective Catalytic Reduction) system that uses ammonia to reduce NOx to nitrogen is known as one of systems for purifying automobile exhaust gas.

  In addition, zeolite is known as a catalyst for adsorbing ammonia and reducing NOx to nitrogen in the SCR system.

  Patent Document 1 discloses a honeycomb structure including a honeycomb unit including a zeolite and an inorganic binder and having a plurality of through holes arranged in parallel in the longitudinal direction with a partition wall therebetween. Further, when manufacturing a honeycomb structure, after forming a honeycomb formed body by extruding a raw material paste containing zeolite, an inorganic binder, and water, the honeycomb formed body is dried using a microwave dryer. Is disclosed.

International Publication No. 09/141897

  However, when the honeycomb molded body is dried using a microwave dryer, the temperature of the honeycomb molded body containing water rises, but the temperature of the atmosphere existing around the honeycomb molded body hardly rises. The heat of the outer periphery of the body is dissipated to the atmosphere. At this time, since the honeycomb formed body containing zeolite and an inorganic binder has a low thermal conductivity, the heat inside the honeycomb formed body is not efficiently conducted to the outer peripheral portion, and the temperature difference between the inner and outer peripheral portions becomes large. Thus, there is a problem that cracks are likely to occur in the honeycomb formed body. In addition, if the output of the microwave dryer is reduced in order to reduce the temperature difference between the inside and the outer periphery of the honeycomb formed body, it takes a long time to dry the honeycomb formed body and the production efficiency decreases. There is.

In view of the problem of the prior art described above has, while suppressing the generation of cracks, a manufacturing method and a manufacturing method of the ceramic sintered body in a short time possible to dry the ceramic molded body ceramic fired body and to provide a manufacturing how the honeycomb structure used.

The method for producing a ceramic fired body according to the present invention includes a ceramic molded body in which a plurality of through holes are arranged in parallel in the longitudinal direction with partition walls formed by extrusion using a raw material paste containing water , zeolite, and an inorganic binder. a process of forming, the ceramic molded body in a state where the longitudinal direction is arranged to be substantially parallel to the horizontal plane, under the following reduced pressure atmosphere 20 kPa above 2 kPa, the ceramic from above the ceramic green body While irradiating the molded body with microwaves, irradiating both longitudinal end faces of the ceramic molded body with infrared rays and drying the ceramic molded body, and firing the dried ceramic molded body The process of producing.

The raw material paste preferably further includes one or more selected from the group consisting of inorganic fibers, scale-like substances, tetrapot-like substances, and three-dimensional needle-like substances.

  The zeolite is preferably a phosphate-based zeolite.

  When irradiating the infrared rays, it is desirable to use a lamp heater, a halogen heater or a far infrared heater.

  When drying the ceramic molded body, a drying device is used. The drying device includes a drying chamber that dries the ceramic molded body, a decompression unit that depressurizes the drying chamber, and the ceramic molded body in the drying chamber. It is desirable to have microwave irradiating means for irradiating microwaves and infrared irradiating means for irradiating infrared rays to both longitudinal end faces of the ceramic molded body in the drying chamber.

  The drying device is preferably a continuous type.

  The method for manufacturing a honeycomb structured body of the present invention includes a step of manufacturing a ceramic fired body using the method for manufacturing a ceramic fired body of the present invention.

According to the present invention, it is possible to suppress the generation of cracks, prepared how a honeycomb structure using the method for fabricating the preparation and the ceramic fired bodies dried to possible ceramic fired body of the ceramic molded body in a short time it is possible to provide a.

It is a perspective view which shows an example of the honeycomb structure manufactured by this invention. It is a side view which shows an example of the drying apparatus of this invention. It is a top view which shows an example of the drying apparatus of this invention. It is sectional drawing which shows an example of the exhaust gas purification apparatus manufactured by this invention. It is a perspective view which shows the other example of the honeycomb structure manufactured by this invention. FIG. 6 is a perspective view showing a honeycomb unit constituting the honeycomb structure of FIG. 5.

  Next, the form for implementing this invention is demonstrated with drawing.

  As an example of the method for manufacturing a honeycomb structure of the present invention, a method for manufacturing the honeycomb structure 10 (see FIG. 1) will be described.

  First, it extrudes using the raw material paste containing water, a zeolite, and an inorganic binder, and produces the cylindrical ceramic molded object by which the several through-hole was arranged in parallel by the longitudinal direction across the partition.

  Zeolite contained in the raw material paste is not particularly limited, but β-type zeolite, Y-type zeolite, ferrierite, ZSM-5-type zeolite, mordenite, faujasite, zeolite A, zeolite L, phosphate zeolite, etc. 2 or more may be used in combination. Among them, phosphate zeolite is preferable because of its excellent NOx purification performance.

  Examples of the phosphate zeolite include SAPO such as SAPO-5, SAPO-11, and SAPO-34, MeAPO, MeAPSO, and the like.

  The zeolite is preferably ion-exchanged with copper ions and / or iron ions in consideration of NOx purification performance.

  Zeolite ion-exchanged with copper ions and / or iron ions preferably has an ion exchange amount of 1.0 to 5.0% by mass. When the ion exchange amount of the zeolite is less than 1.0% by mass, the NOx purification performance becomes insufficient. On the other hand, when the ion exchange amount of the zeolite exceeds 5.0% by mass, the framework structure of the zeolite is broken by the influence of water and heat starting from the ion exchanged site, and the ion exchanged metal ion becomes a metal oxide. , NOx purification performance becomes insufficient.

  Note that the zeolite may be ion-exchanged with metal ions other than those described above.

  The average particle size of the primary particles or secondary particles of the zeolite is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm. When the average particle size of the primary particles or secondary particles of the zeolite is less than 0.5 μm, the porosity of the honeycomb unit 11 is reduced due to the filling effect of the zeolite, so that the exhaust gas hardly penetrates into the partition walls 11b. Zeolite is not effectively used for NOx purification. On the other hand, if the average particle size of the primary particles or secondary particles of the zeolite exceeds 10 μm, the surface area of the honeycomb unit 11 becomes small, so the area where the exhaust gas contacts the zeolite becomes small, and the NOx purification performance becomes insufficient. .

  The honeycomb unit 11 preferably has a zeolite content per apparent volume of 230 to 360 g / L. If the zeolite content per apparent volume of the honeycomb unit 11 is less than 230 g / L, the NOx purification performance will be insufficient. On the other hand, when the content of zeolite per apparent volume of the honeycomb unit 11 exceeds 360 g / L, the content of the inorganic binder in the honeycomb unit 11 becomes small, and the strength of the honeycomb unit 11 becomes insufficient. The aperture ratio of the honeycomb unit 11 is reduced, and the pressure loss is increased.

  The inorganic binder contained in the raw material paste is not particularly limited, and examples thereof include solids contained in alumina sol, silica sol, titania sol, water glass, sepiolite, attapulgite, boehmite, etc., and two or more kinds may be used in combination.

  The content of the inorganic binder in the honeycomb unit 11 is preferably 5 to 30% by mass, and more preferably 10 to 20% by mass. When the content of the inorganic binder in the honeycomb unit 11 is less than 5% by mass, the strength of the honeycomb unit 11 is lowered. On the other hand, if the content of the inorganic binder in the honeycomb unit 11 exceeds 30% by mass, the content of zeolite in the honeycomb unit 11 becomes small, and the NOx purification performance becomes insufficient.

  In order to improve the strength of the honeycomb unit 11, the raw material paste preferably further includes at least one selected from the group consisting of inorganic fibers, scale-like substances, tetrapot-like substances, and three-dimensional needle-like substances.

  The inorganic fibers contained in the raw material paste are not particularly limited as long as the strength of the honeycomb unit 11 can be improved, but alumina, silica, silicon carbide, silica alumina, glass, potassium titanate, aluminum borate, etc. And two or more of them may be used in combination.

  The aspect ratio of the inorganic fiber is preferably 2 to 1000, more preferably 5 to 800, and particularly preferably 10 to 500. When the aspect ratio of the inorganic fibers is less than 2, the effect of improving the strength of the honeycomb unit 11 is reduced. On the other hand, when the aspect ratio of the inorganic fiber exceeds 1000, the mold is clogged when the honeycomb unit 11 is extruded, or the inorganic fiber breaks and the effect of improving the strength of the honeycomb unit 11 is reduced. Or

  The scaly substance means a flat substance, preferably having a thickness of 0.2 to 5 μm, preferably having a maximum length of 10 to 160 μm, and having a ratio of the maximum length to the thickness. It is preferable that it is 3-250.

  The scaly substance contained in the raw material paste is not particularly limited as long as the strength of the honeycomb unit 11 can be improved, and examples thereof include glass, muscovite, alumina, silica, and the like. Also good.

  The tetrapot-like substance means a substance in which the needle-like portion extends three-dimensionally. The average needle-like length of the needle-like portion is preferably 5 to 30 μm, and the average diameter of the needle-like portion is 0.5. It is preferably ~ 5 μm.

  Examples of the tetrapot-like substance include single crystals and whiskers.

  Although it does not specifically limit as a material which comprises the tetrapod-like substance contained in a raw material paste, Zinc oxide etc. are mentioned, You may use 2 or more types together.

  The three-dimensional acicular substance means a substance in which the acicular parts are bonded by an inorganic compound such as glass near the center of each acicular part, and the average acicular length of the acicular parts is 5 to 30 μm. It is preferable that the average diameter of the acicular portion is 0.5 to 5 μm.

  The three-dimensional needle-like substance may have a plurality of needle-like portions that are three-dimensionally connected. The needle-like portion preferably has a diameter of 0.1 to 5 μm and a length of 0.3 to 30 μm. It is preferable that the ratio of length to diameter is 1.4 to 50.

  The material constituting the three-dimensional acicular substance contained in the raw material paste is not particularly limited, and examples thereof include alumina, silica, silicon carbide, silica alumina, glass, potassium titanate, aluminum borate, boehmite, and zinc oxide. Two or more kinds may be used in combination.

  The content of one or more selected from the group consisting of inorganic fibers, scale-like substances, tetrapot-like substances and three-dimensional needle-like substances in the honeycomb unit 11 is preferably 3 to 50% by mass, and 3 to 30 % By weight is more preferable, and 5 to 20% by weight is particularly preferable. When the content of one or more selected from the group consisting of inorganic fibers, scale-like substances, tetrapot-like substances and three-dimensional needle-like substances in the honeycomb unit 11 is less than 3% by mass, the strength of the honeycomb unit 11 is improved. The effect to make becomes small. On the other hand, when the content of one or more selected from the group consisting of inorganic fibers, scale-like substances, tetrapot-like substances and three-dimensional needle-like substances in the honeycomb unit 11 exceeds 50% by mass, the zeolite in the honeycomb unit 11 As a result, the NOx purification performance decreases.

  Moreover, you may add an organic binder, a dispersion medium, a shaping | molding adjuvant, etc. to a raw material paste suitably as needed.

  Although it does not specifically limit as an organic binder, Methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethyleneglycol, a phenol resin, an epoxy resin etc. are mentioned, You may use 2 or more types together. In addition, it is preferable that the addition amount of an organic binder is 1-10% with respect to the total mass of a zeolite, an inorganic binder, an inorganic fiber, a scale-like substance, a tetrapot-like substance, and a three-dimensional acicular substance.

  Although it does not specifically limit as a dispersion medium, Alcohol, such as water, organic solvents, such as benzene, methanol, etc. are mentioned, You may use 2 or more types together.

  Although it does not specifically limit as a shaping | molding adjuvant, Ethylene glycol, dextrin, a fatty acid, fatty acid soap, a polyalcohol etc. are mentioned, You may use together 2 or more types.

  When preparing the raw material paste, it is preferable to mix and knead, and it may be mixed using a mixer, an attritor or the like, or may be kneaded using a kneader or the like.

  Next, the obtained ceramic molded body is dried using the drying apparatus of the present invention.

  2 and 3 show an example of the drying apparatus of the present invention. The drying apparatus 100 is a continuous type, and the buffer chamber 110, the decompression chamber 120, the drying chamber 130, the decompression chamber 140, and the buffer chamber 150 are sequentially installed in the direction in which the ceramic molded body C is conveyed. The molded body C is conveyed by the conveyor 170 in a state of being fixed to the jig 160. At this time, the decompression chamber 120, the drying chamber 130, and the decompression chamber 140 can be decompressed by a decompression device (not shown). In addition, a microwave irradiation device 131 for irradiating the ceramic molded body C with microwaves is installed in the upper portion of the drying chamber 130. Further, on both side portions of the drying chamber 130, infrared irradiation devices 132 that irradiate infrared rays to both end surfaces of the ceramic molded body C in the longitudinal direction are installed.

  When the ceramic compact C passes between the buffer chamber 110, the decompression chamber 120, the drying chamber 130, the decompression chamber 140, and the buffer chamber 150 in order to maintain the decompression of the decompression chamber 120 and the drying chamber 130. A door (not shown) that can be opened and closed is installed.

  Although it does not specifically limit as a decompression device, A vacuum pump etc. are mentioned.

  The microwave irradiation device 131 is not particularly limited as long as microwave irradiation can be performed.

  Although it does not specifically limit as the infrared irradiation apparatus 132, A lamp heater, a halogen heater, a far-infrared heater, LT heater, a Colts heater, a carbon heater, a Kolce heater, a quartz tube heater etc. are mentioned. Among these, a lamp heater, a halogen heater, and a far infrared heater are preferable.

  Next, a method for drying the ceramic molded body C using the drying apparatus 100 will be described. First, in the buffer chamber 110, the ceramic molded body C is fixed to the jig 160 so that the longitudinal direction of the ceramic molded body C is substantially perpendicular to the direction in which the ceramic molded body C is conveyed by the conveyor 170. Next, the ceramic molded body C is conveyed by the conveyor 170 through the decompression chamber 120 decompressed by the decompression device (not shown) to the drying chamber 130 decompressed by the decompression device (not shown). .

  At this time, the pressure in the drying chamber 130 is 1 to 50 kPa, preferably 2 to 50 kPa, more preferably 2 to 20 kPa, and further preferably 3 to 10 kPa. When the pressure in the drying chamber 130 is less than 1 kPa, it becomes easy to discharge. On the other hand, when the pressure in the drying chamber 130 exceeds 50 kPa, the temperature difference between the inside and the outer periphery of the ceramic molded body C increases, and cracks are likely to occur in the ceramic molded body C.

  Moreover, although the drying chamber 130 is not normally heated, you may heat as needed.

  Furthermore, the atmosphere in the drying chamber 130 is normally air, but may be replaced with an inert gas such as nitrogen gas as necessary.

  Next, when the ceramic molded body C is conveyed to the drying position in the drying chamber 130, the conveyance of the ceramic molded body C by the conveyor 170 is stopped for a predetermined time. During this time, the microwave irradiation device 131 and the infrared irradiation device 132 irradiate the ceramic molded body C with microwaves and irradiate both end faces in the longitudinal direction of the ceramic molded body C with infrared rays.

  When the ceramic molded body C is irradiated with microwaves, the temperature of the ceramic molded body C rises and water contained in the ceramic molded body C evaporates. At this time, since the heat of the outer peripheral portion of the honeycomb formed body C is radiated to the atmosphere, a temperature difference is generated between the inside and the outer peripheral portion of the ceramic formed body C. However, since the pressure in the drying chamber 130 is 1 to 50 kPa, the temperature at which water evaporates decreases, and the temperature difference between the inside and the outer periphery of the ceramic molded body C can be reduced. As a result, generation of cracks in the ceramic molded body C can be suppressed.

  The outer peripheral portion of the ceramic molded body C includes both end portions in the longitudinal direction of the ceramic molded body C.

  On the other hand, both ends in the longitudinal direction of the ceramic molded body C have a larger amount of heat dissipated than the center in the longitudinal direction of the ceramic molded body C, but infrared rays are irradiated to both longitudinal ends of the ceramic molded body C. And since the temperature of the both ends of the longitudinal direction of the ceramic molded body C rises, the temperature difference of the center part of the longitudinal direction of the ceramic molded body C and both ends can be made still smaller.

  In addition, the irradiation amount of a microwave and infrared rays can be suitably adjusted according to the material which comprises the ceramic molded body C, the size of the ceramic molded body C, the pressure in the drying chamber 130, etc.

  Further, the ceramic molded body C may be dried by stopping the conveyance of the ceramic molded body C by the conveyor 170 for a predetermined time at a plurality of drying positions.

  Further, when the temperature difference between the inside and the outer periphery of the ceramic molded body C can be reduced without irradiating both longitudinal end faces of the ceramic molded body C with infrared rays, the infrared rays are not irradiated. May be.

  The ceramic molded body C dried as described above is transported to the buffer chamber 150 by the conveyor 170 via the decompression chamber 140 decompressed by a decompression device (not shown) and collected.

  Further, the recovered ceramic molded body C is degreased. The degreasing conditions are not particularly limited and can be appropriately selected depending on the type and amount of the organic substance contained in the ceramic molded body C, but it is preferably 400 ° C. for 2 hours.

  Next, by firing the degreased ceramic molded body, the cylindrical honeycomb unit 11 is obtained. The firing temperature is preferably 600 to 1200 ° C, more preferably 600 to 1000 ° C. When the firing temperature is less than 600 ° C., the condensation reaction via the inorganic binder does not proceed, and the strength of the honeycomb unit 11 is lowered. On the other hand, if the calcining temperature exceeds 1200 ° C., the sintering of the zeolite proceeds too much and the reaction sites of the zeolite decrease.

  Next, the outer peripheral coat layer paste is applied to the outer peripheral surface excluding both end surfaces of the columnar honeycomb unit 11.

  Although it does not specifically limit as a paste for outer periphery coating layers, The mixture of an inorganic binder and an inorganic particle, the mixture of an inorganic binder and an inorganic fiber, the mixture of an inorganic binder, an inorganic particle, and an inorganic fiber etc. are mentioned.

  Moreover, the outer periphery coating layer paste may further contain an organic binder.

  Although it does not specifically limit as an organic binder, Polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose, etc. are mentioned, You may use 2 or more types together.

  Next, by drying and solidifying the honeycomb unit 11 to which the outer periphery coating layer paste has been applied, a cylindrical honeycomb structure 10 is obtained. At this time, when the outer peripheral coat layer paste contains an organic binder, it is preferably degreased. The degreasing conditions can be appropriately selected depending on the type and amount of the organic substance, but it is preferably 20 minutes at 700 ° C.

  Note that the zeolite can be ion-exchanged by immersing the honeycomb unit 11 in an aqueous solution containing copper ions and / or iron ions. Moreover, you may produce the honeycomb unit 11 using the raw material paste containing the zeolite ion-exchanged with a copper ion and / or an iron ion.

  In the honeycomb structure 10, an outer peripheral coat layer 12 is formed on the outer peripheral surface of a single honeycomb unit 11 in which a plurality of through holes 11 a are arranged in parallel in the longitudinal direction with a partition wall 11 b interposed therebetween.

  The honeycomb unit 11 preferably has a porosity of 25 to 40%. When the porosity of the honeycomb unit 11 is less than 25%, the exhaust gas hardly penetrates into the partition walls 11b, and the zeolite is not effectively used for purification of NOx. On the other hand, when the porosity of the honeycomb unit 11 exceeds 40%, the strength of the honeycomb unit 11 becomes insufficient.

  The honeycomb unit 11 preferably has an opening ratio of a cross section perpendicular to the longitudinal direction of 50 to 75%. If the opening ratio of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is less than 50%, the zeolite is not effectively used for purification of NOx. On the other hand, if the opening ratio of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 exceeds 75%, the strength of the honeycomb unit 11 becomes insufficient.

In the honeycomb unit 11, the density of the through holes 11 a having a cross section perpendicular to the longitudinal direction is preferably 31 to 140 / cm ² . When the density of the through-holes 11a having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11 is less than 31 / cm ² , it becomes difficult for the exhaust gas and zeolite to come into contact with each other, and the NOx purification performance decreases. On the other hand, when the density of the through holes 11a having a cross section perpendicular to the longitudinal direction of the honeycomb unit 11 exceeds 140 / cm ² , the pressure loss of the honeycomb structure 10 increases.

  The thickness of the partition wall 11b of the honeycomb unit 11 is preferably 0.10 to 0.50 mm, and more preferably 0.15 to 0.35 mm. When the thickness of the partition wall 11b is less than 0.10 mm, the strength of the honeycomb unit 11 is lowered. On the other hand, when the thickness of the partition wall 11b exceeds 0.50 mm, the exhaust gas hardly penetrates into the partition wall 11b, and the zeolite is not effectively used for purification of NOx.

  The outer peripheral coat layer 12 preferably has a thickness of 0.1 to 2 mm. When the thickness of the outer peripheral coat layer 12 is less than 0.1 mm, the effect of improving the strength of the honeycomb structure 10 becomes insufficient. On the other hand, when the thickness of the outer peripheral coat layer 12 exceeds 2 mm, the content of phosphoric acid-based zeolite per unit volume of the honeycomb structure 10 is lowered, and the NOx purification performance is lowered.

  The honeycomb structure 10 (see FIG. 1) has a columnar shape, but is not particularly limited, and may have a prismatic shape, an elliptical column shape, or the like. Moreover, although the shape of the through-hole 11a (refer FIG. 1) is a square pillar shape, it is not specifically limited, A triangular prism shape, hexagonal column shape, etc. may be sufficient.

  The honeycomb structure 10 may not have the outer peripheral coat layer 12 formed thereon.

  Further, the exhaust gas purification apparatus 1000 (see FIG. 4) can be obtained by performing canning on the metal tube 30 in a state where the holding sealing material 20 is disposed on the outer peripheral portion of the honeycomb structure 10. The exhaust gas purification apparatus 1000 is provided with injection means (not shown) such as an injection nozzle that injects ammonia or a compound that generates ammonia by decomposition on the upstream side of the honeycomb structure 10 with respect to the flow direction of the exhaust gas. ing. Thereby, since ammonia is added to the exhaust gas, the NOx contained in the exhaust gas is reduced by the zeolite contained in the honeycomb unit 11.

  The compound that decomposes to generate ammonia is not particularly limited as long as ammonia can be generated in the exhaust gas, but urea water is preferable in consideration of storage stability.

  The urea water is heated by the exhaust gas and hydrolyzed to generate ammonia.

  Next, as another example of the method for manufacturing a honeycomb structure of the present invention, a method for manufacturing a honeycomb structure 10 ′ (see FIG. 5) will be described. First, in the same manner as the honeycomb unit 11, a quadrangular prism-shaped honeycomb unit 11 ′ is manufactured. Next, an adhesive layer paste is applied to the outer peripheral surface excluding both end faces of the honeycomb unit 11 ′, the honeycomb units 11 ′ are sequentially bonded, and dried and solidified to produce an aggregate of the honeycomb units 11 ′.

  At this time, after the assembly of the rectangular columnar honeycomb units 11 ′ is manufactured, the columnar honeycomb unit 11 ′ may be manufactured by cutting into a cylindrical shape and polishing. Alternatively, a columnar honeycomb unit 11 ′ may be manufactured by bonding honeycomb units 11 ′ whose cross section perpendicular to the longitudinal direction is formed in a fan shape, a square shape, or the like.

  Although it does not specifically limit as a paste for contact bonding layers, The mixture of an inorganic binder and an inorganic particle, the mixture of an inorganic binder and an inorganic fiber, the mixture of an inorganic binder, an inorganic particle, and an inorganic fiber etc. are mentioned.

  The adhesive layer paste may contain an organic binder.

  Although it does not specifically limit as an organic binder, Polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose, etc. are mentioned, You may use 2 or more types together.

  Next, the outer peripheral coat layer paste is applied to the outer peripheral surface excluding both end surfaces of the aggregate of the cylindrical honeycomb unit 11 ′.

  The outer periphery coat layer paste is not particularly limited, but may include the same material as the adhesive layer paste, or may include a different material. Further, the outer peripheral coat layer paste may have the same composition as the adhesive layer paste.

  Next, by drying and solidifying the aggregate of the honeycomb units 11 to which the outer peripheral coat layer paste has been applied, a cylindrical honeycomb structure 10 ′ is obtained. At this time, when an organic binder is contained in the adhesive layer paste and / or the outer periphery coat layer paste, it is preferable to degrease the aggregate of the honeycomb units 11 to which the outer periphery coat layer paste is applied. The degreasing conditions can be appropriately selected depending on the type and amount of the organic substance, but it is preferably 20 minutes at 700 ° C.

  The honeycomb structure 10 ′ has a configuration in which a plurality of honeycomb units 11 ′ (see FIG. 6) in which a plurality of through holes 11 a are arranged in parallel in the longitudinal direction with a partition wall 11 b interposed therebetween are bonded via an adhesive layer 13. This is the same as the honeycomb structure 10.

The honeycomb unit 11 ′ preferably has a cross-sectional area of 5 to 50 cm ² in a cross section perpendicular to the longitudinal direction. When the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 ′ is less than 5 cm ² , the pressure loss of the honeycomb structure 10 ′ increases. On the other hand, if the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 ′ exceeds 50 cm ² , the strength against the thermal stress generated in the honeycomb unit 11 becomes insufficient.

  The characteristics other than the cross-sectional area of the cross section perpendicular to the longitudinal direction of the honeycomb unit 11 ′ are the same as those of the honeycomb unit 11.

  The adhesive layer 13 preferably has a thickness of 0.5 to 2 mm. When the thickness of the adhesive layer 13 is less than 0.5 mm, the adhesive strength of the honeycomb unit 11 becomes insufficient. On the other hand, when the thickness of the adhesive layer 13 exceeds 2 mm, the pressure loss of the honeycomb structure 10 ′ increases.

  Further, the shape of the honeycomb unit 11 ′ excluding the honeycomb unit 11 ′ located on the outer peripheral portion of the honeycomb structure 10 ′ is a quadrangular prism shape, but is not particularly limited, and may be, for example, a hexagonal column shape.

  The honeycomb structure 10 ′ may not have the outer peripheral coat layer 12 formed thereon.

  The case where the honeycomb unit 11 or 11 ′ is manufactured as the ceramic fired body has been described above, but the shape of the ceramic fired body is not particularly limited. The material constituting the ceramic fired body is not particularly limited, and examples thereof include alumina, silica, titania, zirconia, ceria, mullite, zeolite, cordierite, aluminum titanate, and silicon nitride.

  The drying apparatus of the present invention is effective when manufacturing a ceramic fired body (honeycomb unit) using such a material, and is particularly effective when manufacturing a ceramic fired body (honeycomb unit) containing zeolite. .

  In this embodiment, the part means part by mass.

[Example 1]
3,000 parts SAPO-34 having an average primary particle diameter of 3 μm, 840 parts boehmite, 650 parts alumina fiber having an average fiber diameter of 6 μm and an average fiber length of 100 μm, 330 parts methylcellulose, 330 parts oleic acid and 1800 ion-exchanged water Parts were mixed and kneaded to prepare a raw material paste.

  Next, the raw material paste was extrusion-molded using an extrusion molding machine to produce a regular quadrangular prism-shaped ceramic molded body. Then, using the drying apparatus 100, the pressure in the drying chamber 130 is set to 6.7 kPa, the drying chamber 130 is not heated, the atmosphere in the drying chamber 130 is set to the atmosphere, and the ceramic molded body is placed for 15 minutes (0.25 hours). ) Dried. At this time, the output of each microwave irradiation apparatus 131 was 6 kW. Moreover, as the infrared irradiation device 132, an infrared heater was used, and the output of each infrared heater was set to 150W.

  At this time, the ceramic molded body had a temperature difference of 2.5 ° C. between the inner portion and the outer peripheral portion, and the crack generation rate was 0%.

  The temperature difference between the inside and the outer periphery of the ceramic molded body is determined by placing an optical fiber thermometer (manufactured by Neooptix) near the center near the end face of the ceramic molded body and near the corner near the end face. Measured and calculated.

  The occurrence rate of cracks in the ceramic molded body was determined by visually evaluating whether or not 100 ceramic molded bodies were transported to the buffer chamber 150.

Next, the dried ceramic molded body was degreased at 400 ° C. for 5 hours and then fired at 700 ° C. for 2 hours to produce a regular square columnar honeycomb unit 11 ′ (see FIG. 6) having a side of 38 mm and a length of 150 mm. did. In the honeycomb unit 11 ′, the density of the through holes 11a was 62 / cm ² , and the thickness of the partition walls 11b was 0.28 mm.

  Next, 767 parts of alumina fiber having an average fiber diameter of 0.5 μm and an average fiber length of 15 μm, 2500 parts of silica glass, 17 parts of carboxymethylcellulose, 600 parts of silica sol having a solid content of 30% by mass, 167 parts of polyvinyl alcohol, a surfactant 167 parts and 17 parts of alumina balloon were mixed and kneaded to prepare a heat-resistant adhesive layer paste.

  After applying the adhesive layer paste so that the thickness of the adhesive layer is 2 mm and adhering 16 honeycomb units 11 ′, the adhesive layer paste is dried and solidified at 150 ° C. for 10 minutes to form a regular quadrangular prism shape. An aggregate of the honeycomb unit 11 ′ was prepared. Next, using a diamond cutter, the aggregate of the regular square pillar-shaped honeycomb units 11 ′ is cut into a cylindrical shape so that the cross section perpendicular to the longitudinal direction is substantially point-symmetric, and the cylindrical honeycomb unit 11 ′ is cut. An assembly was produced.

  Further, after the adhesive layer paste is applied to the outer peripheral surface of the aggregate of the honeycomb unit 11 ′ so that the thickness of the outer peripheral coat layer becomes 1 mm, it is used for the adhesive layer using a microwave dryer and a hot air dryer. The paste was dried and solidified at 150 ° C. for 10 minutes and degreased at 400 ° C. for 2 hours to produce a cylindrical honeycomb structure 10 ′ (see FIG. 5) having a diameter of 143.8 mm and a height of 150 mm.

  Next, in a state where the holding sealing material (mat made of inorganic fibers) 20 is disposed on the outer peripheral portion of the honeycomb structure 10 ′, the honeycomb structure 10 ′ is canned to the metal pipe (shell) 30 to produce an exhaust gas purification device (see FIG. 2). .

[ Reference Example 2]
A honeycomb structure 10 ′ and an exhaust gas purification device were produced in the same manner as in Example 1 except that when the ceramic molded body was dried, infrared rays were not irradiated.

  At this time, the ceramic molded body had a temperature difference of 14.8 ° C. between the inside and the outer periphery, and a crack generation rate of 5%.

[ Reference Example 3]
A honeycomb structure 10 ′ and an exhaust gas purification device were produced in the same manner as in Reference Example 2 except that the pressure in the drying chamber 130 was set to 2.0 kPa.

  At this time, the ceramic molded body had a temperature difference of 1.2 ° C. between the inside and the outer periphery, and the crack generation rate was 0%.

[ Reference Example 4]
A honeycomb structure 10 ′ and an exhaust gas purification device were produced in the same manner as in Reference Example 2 except that the pressure in the drying chamber 130 was changed to 50.0 kPa.

  At this time, the ceramic molded body had a temperature difference of 20.4 ° C. between the inside and the outer periphery, and the crack generation rate was 8%.

[Comparative Example 1]
A honeycomb structure and an exhaust gas purification device were manufactured in the same manner as in Example 2 except that the pressure in the drying chamber 130 was set to 101.3 kPa when the ceramic molded body was dried.

  At this time, the ceramic molded body had a temperature difference of 35.0 ° C. between the inner part and the outer peripheral part, and the crack generation rate was 100%.

[Comparative Example 2]
When the ceramic molded body was dried, the pressure in the drying chamber 130 was set to 86.7 kPa, the output of each microwave irradiation device 131 was set to 60 W, the output of each infrared heater was set to 10 W, and the drying was performed for 24 hours. In the same manner as in Example 1, a honeycomb structure and an exhaust gas purification device were produced.

  At this time, the ceramic molded body had a temperature difference of 10.4 ° C. between the inner part and the outer peripheral part, and the crack generation rate was 0%.

[Comparative Example 3]
A honeycomb structure and an exhaust gas purification device were produced in the same manner as in Example 2 except that the pressure in the drying chamber 130 was changed to 86.7 kPa when the ceramic molded body was dried.

  At this time, the ceramic molded body had a temperature difference of 32.1 ° C. between the inner part and the outer peripheral part, and the occurrence rate of cracks was 100%.

  Table 1 shows the drying conditions and the evaluation results of the ceramic molded body.

表１より、実施例１、参考例２〜４のハニカムユニット１１’を製造する場合、セラミック成形体を乾燥させる時間が１５分間（０．２５時間）であっても、セラミック成形体の内部と外周部の温度差が小さくなって、セラミック成形体にクラックが発生することを抑制できることがわかる。また、実施例１のように、セラミック成形体を乾燥させる際に、セラミック成形体の長手方向の両端面に赤外線を照射すると、セラミック成形体の内部と外周部の温度差がさらに小さくなって、セラミック成形体にクラックが発生することをさらに抑制できることがわかる。

From Table 1, when manufacturing the honeycomb unit 11 ′ of Example 1 and Reference Examples 2 to 4, even if the time for drying the ceramic molded body is 15 minutes (0.25 hours), It turns out that the temperature difference of an outer peripheral part becomes small and it can suppress that a crack generate | occur | produces in a ceramic molded object. Further, as in Example 1, when drying the ceramic molded body, when infrared rays are applied to both end faces in the longitudinal direction of the ceramic molded body, the temperature difference between the inside and the outer periphery of the ceramic molded body is further reduced. It can be seen that the generation of cracks in the ceramic molded body can be further suppressed.

  On the other hand, when the honeycomb units of Comparative Examples 1 and 3 are manufactured, if the time for drying the ceramic molded body is 15 minutes (0.25 hours), the pressure in the drying chamber 130 is greater than 50 kPa, so It is considered that the temperature difference between the inside and the outer periphery of the body becomes large, and cracks are likely to occur in the ceramic molded body.

  Further, when the honeycomb unit of Comparative Example 2 is manufactured, since the pressure in the drying chamber 130 is larger than 50 kPa, the output of the microwave irradiation device 131 is set in order to suppress the occurrence of cracks in the ceramic molded body. It can be seen that it is necessary to decrease the temperature and to irradiate infrared rays on both end faces of the ceramic molded body in the longitudinal direction and to dry for 24 hours.

From Example 1 and Reference Examples 2 to 4, a method for manufacturing a ceramic fired body capable of suppressing generation of cracks and drying a ceramic molded body in a short time, and a honeycomb structure using the method for producing the ceramic fired body body of production how it can be seen that the can provide.

DESCRIPTION OF SYMBOLS 10, 10 'Honeycomb structure 11, 11' Honeycomb unit 11a Through-hole 11b Partition 12 Outer peripheral coat layer 13 Adhesive layer 20 Holding sealing material 30 Metal tube 100 Drying device 130 Drying chamber 131 Microwave irradiation device 132 Infrared irradiation device 1000 Exhaust gas purification apparatus

Claims (7)

Extruding using a raw material paste containing water , zeolite and an inorganic binder , and producing a ceramic molded body in which a plurality of through holes are arranged in parallel in the longitudinal direction across a partition ;
In a state where the ceramic molded body is arranged so that the longitudinal direction is substantially parallel to a horizontal plane , a microwave is applied to the ceramic molded body from above the ceramic molded body in a reduced pressure atmosphere of 2 kPa to 20 kPa. Irradiating infrared rays to both longitudinal ends of the ceramic molded body while irradiating the ceramic molded body, and drying the ceramic molded body,
A process for producing a ceramic fired body comprising firing the dried ceramic molded body to produce a ceramic fired body. The raw material paste, inorganic fibers, the manufacture of scaly substance, the ceramic sintered body according to claim 1, further comprising a least one selected from the group consisting of tetrapod-like materials and three-dimensional needles Method. The method for producing a fired ceramic body according to claim 1 or 2 , wherein the zeolite is a phosphate-based zeolite. Wherein when irradiating the infrared lamp heater, a manufacturing method of a ceramic fired body according to any one of claims 1 to 3, characterized by using a halogen heater or a far infrared heater. When drying the ceramic molded body, using a drying device,
The drying apparatus includes: a drying chamber that dries the ceramic molded body; a decompression unit that depressurizes the drying chamber; a microwave irradiation unit that irradiates the ceramic molded body in the drying chamber with microwaves; The method for producing a ceramic fired body according to any one of claims 1 to 4, further comprising infrared irradiation means for irradiating infrared rays to both longitudinal end faces of the ceramic molded body. The said drying apparatus is a continuous type, The manufacturing method of the ceramic sintered body of Claim 5 characterized by the above-mentioned. A method for manufacturing a honeycomb structured body comprising a step of manufacturing a ceramic fired body using the method for manufacturing a ceramic fired body according to any one of claims 1 to 6 .

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