JPS593059A - Manufacture of cordierite ceramic foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cordierite ceramic foam used as a catalyst carrier for automobile exhaust gas treatment, and more specifically, a cordierite ceramic foam that has excellent thermal shock resistance and low pressure loss. This relates to the foam manufacturing method.

The cordierite ceramic foam is made of cordierite ceramic material and has a three-dimensional network cell structure with internal communication spaces.

In recent years, cordierite ceramic foam has been in the spotlight because it is ideal as a catalyst carrier for automobile exhaust gas treatment, especially as a carrier for collecting and purifying diesel engine particulates.

However, when used in a car, the following important characteristics are required.

The first characteristic is excellent thermal shock resistance. This is because the temperature inside the carrier rises to 600 to 800°C or more in a few tens of seconds due to heating by exhaust gas or heat generated by a catalytic reaction, and the outside can withstand a temperature difference of 100 to 300°C. This property is achieved by reducing the coefficient of thermal expansion of the cordierite ceramic foam.

The next important characteristic is low pressure loss (small pressure loss during circulation).

If the catalyst has high pressure loss (high pressure loss during circulation),
Excessive load is placed on the automobile engine, deteriorating fuel efficiency and running performance.In addition, especially when used for collecting and purifying diesel particulates, the higher the pressure drop, the less particulates can be collected, and the shorter the time. Therefore, the particulates in the catalyst must be burnt and regenerated by throttling, which is a fatal drawback.

By the way, cordierite ceramic foam is produced by dipping a foam rubber such as urethane foam or plastic foam having communicating holes in a slurry made by dispersing cordierite powder in water, forming a slurry coating with a certain thickness, and drying and sintering the foam. A cordierite relamic porous body having a cell structure almost the same as that of the organic foam described above is produced by this method, but it is extremely difficult to uniformly coat the organic porous body with slurry to a predetermined thickness, and as described above. There is a problem that the characteristic of reducing pressure loss is lost.

Conventionally, as a technology to reduce this pressure loss, Japanese Patent Application Laid-Open No. 1987-
No. 67588 proposes a method of soaking in cordierite slurry and blowing air to remove the mesh after coating with the slurry. However, in this method, removing the internal mesh is difficult due to the three-dimensional structure of the three-dimensional network structure. This was difficult due to air blow-through, and the pressure loss could not be reduced.

In addition, it is generally known that alkaline substances such as feldspar, sodium silicate, and sodium hydroxide are added to the slurry as a method of reducing the viscosity of the cordierite slurry while keeping the same solid content so that it is less likely to sludge when coated with the slurry. However, this leaves components other than cordierite in the product, which impairs the characteristic of Corn 1lite, which has a low coefficient of thermal expansion.

The present invention is easy to manufacture, has high quality, has excellent thermal shock resistance, and has low pressure loss. That is, the object of the present invention is to provide a method for manufacturing a cordierite ceramic foam that is made of cordierite, which has a small coefficient of thermal expansion, and that can ensure communication holes of a predetermined diameter.

The method for producing a cordierite ceramic foam of the present invention involves immersing an organic porous body having a three-dimensional network cell structure in 'X-1-gelite slurry composed of predetermined components;
After the cordierite slurry is coated on the surface, centrifugal force is applied to remove excess cordierite slurry, and then the process of dipping, blowing off, and drying is repeated several times and then sintered at a predetermined temperature. The composition consists of

Next, the present invention will be explained based on embodiments shown in the drawings.

First Example First, a step (1) of producing cordierite slurry with predetermined components
).

Step (1) (A) Take 1.7% by weight of aluminum hydroxide, 31% by weight of talc, and 46% by weight of clay, mix, knead, and dry. This is called raw material powder.

Next, (B) this raw material powder was fired at 1410° C. for 5 hours, and then ground until the average particle size became 10 μ (microns). The chemical composition of this powder is 51% silica and 3% alumina.
6% and 13% magnesia, and X-ray diffraction revealed that the crystal system was all cordierite.

This powder is called cordierite powder.

Next, 70% by weight of the powder and 30% by weight of the raw material powder were taken into <C> Corjelai 1 and dispersed in water, and a polyvinyl alcohol surfactant was added thereto so that the solid content of each was 59%.
Two types of cordierite slurries 2 and 5 were prepared, containing 0% by weight and 63.4% by weight. Viscosity is 8o~100cp each
s, 200-230 cps.

Next, the step (2) of manufacturing a ceramic foam made of Corn 1 Lite using a three-dimensional network-like urethane foam having communicating holes with the Corjelai 1 to Slime 2 and 5 will be described. 2 First, as shown in Figure 1 (D), use a cylindrical shape with a diameter of 1 mm to 3 mm.
mm In this example, a three-dimensional network-like urethane foam 1 having 2 mm communicating holes is coated with cordierite slurry 2 of (E).
immerse it in water to make the slurry 2 adhere to the entire surface. The lower limit of the communicating hole is set to 1 mm because if it is less than 1 mm, clogging tends to occur. After drying, as shown in (F), centrifugal force is applied for 30 seconds at approximately 250 revolutions per minute using a centrifugal blower 3, thereby removing excess slurry 2 (G).
Drying step 4 was performed. Further similar (E), (F),
After repeating step (G), next step is (H) dipping step in slurry 5, blowing off step similar to step (F) using centrifugal blower 3 in (I), and drying step (J). Operation 6 was performed twice. As shown above, the solid content is 63.4% slurry 2 and 2
After repeating immersion, blowing off, and drying two more times in slurry 5 with a solid content of 59.0%, 140°C of (K)
After performing the firing step 6 for x 5hrs, the high density 0.
Product 8 of 3g/CC was obtained.

By repeating immersion, blowing off, and drying several times in the cordierite slurry made of the specified ingredients as described above, clogging in the three-dimensional communication ports is prevented and a layer of uniform thickness is formed. be done.

Further, as shown in Fig. 2.3, the excess A-gelite slurry in (F) and (I) is blown away by decelerating the rotation of the motor 8 equipped with a soft start function with a deceleration 1181, and Centrifugal blow-off machine 3
A predetermined number of three-dimensional reticulated porous bodies 1 after adhering to cargelite slurry are placed in a rotating container 9, and the desired amount is 5 to 10G to 240G.
Apply centrifugal force of 0G to 80Q for 5 to 120 seconds, preferably 10
This is done by adding for about 60 seconds. IO lower limit
The reason why it is overwritten with G is that if it is less than this, the excess Cogelato slurry cannot be sufficiently blown away, and the reason why the upper limit was set at 240G is because it is meaningless to go beyond this.Also, the combination of time is also Same as in case.

For blowing away excess cordierite slurry, it is appropriate to use centrifugal force for materials that do not have straight lines like the three-dimensional network porous material 1 and have three-dimensional communication ports. However, there are some areas that cannot be blown away using conventional methods of blowing compressed air.

The second embodiment will be explained.

The solid content was 61% by weight in the same manner as in Example 1 except that the cordierite powder was 30% by weight and the raw material powder was 70% by weight.
, five types of slurry with a weight of 55% by weight were prepared. Viscosity is 200~
It was 250 cps and 80-100 CpS. This was further coated with slurry and sintered in the same manner as in the first example to obtain a product with a bulk density of 0.3 (+/CC).

Next, first to third comparative examples to be compared to the first to third embodiments according to the present invention will be shown in order.

First Comparative Example A urethane foam having communicating holes of 211 IIll in size was immersed in slurry 2.5 obtained in the same manner as in the first example, and then the excess slurry was blown off and dried with 6 kg 7 cm of compressed air. After repeating this immersion, air blowing, and drying operation four times, the temperature was 1400℃ x 5 hours.
After firing, a product with a high density of 0.3 was obtained.

Second Comparative Example Two types of slurry with a solid content of 56% by weight and 53% by weight were prepared in the same manner as in the first example except that the raw material powder was made 100% by weight. Viscosity is 200~250cps, 80~
It was 100 cps. This slurry was coated with slurry three times at 56% by weight and three times at 53% by weight in the same manner as in Example 1, and then baked at 1400°C for 5hrS'c to obtain a product with a bulk density of 0.3. .

Third Comparative Example A slurry with a solid content of 67% by weight was prepared in the same manner as in Example 1, except that the raw material powder was 95% by weight and the feldspar powder was 5% by weight. This slurry, which had a viscosity of 200 to 250 cps, was coated with the slurry four times in the same manner as in Example 1.
After firing at 60°C for 5 hours, a product with a bulk density of 0.3 was obtained.

Table 1 shows the characteristics when the above-mentioned Example 1.2 and Comparative Example 1.2.3 were carried out using a carrier having a diameter of 93 mm and a height of 66 mm.

Table 1 As shown in Table 1 above, the slurry components in the first sample of the present invention.
The firing temperature was also the same as or equivalent to Example 2.
In the first comparative example, the temperature was the same as in the example, 1400°C (supposed to be the best for producing cordierite), the excess slurry was blown away with compressor air, and the solid content of the slurry was 100% by weight of the raw material powder. In the second comparative example, which was otherwise the same as the first example of the present invention, the pressure loss was significantly large in both cases, and the solid content of the slurry was reduced to 95% by weight of the raw material powder.
In the third comparative example, which contained 5% by weight of feldspar powder, the firing temperature was 1350° C., and was otherwise the same as the first example of the present invention, the coefficient of thermal expansion was large, and therefore it was susceptible to thermal shock.

As described above, the method for producing a cordierite ceramic foam of the present invention involves immersing an organic porous body having a three-dimensional network cell structure in a cordierite slurry made of predetermined components, and coating the cordierite slurry on the surface. After the cordierite has been coated with a material, centrifugal force is applied to remove excess cordierite slurry, and the process of soaking, blowing off, and drying is repeated several times, and then sintering is performed at a predetermined temperature. It is easy to manufacture because it is manufactured by direct coating using the structure of a three-dimensional network-like organic porous material, and it ensures continuous pores with a predetermined diameter and a rope-like wall with a uniform thickness and large surface area. Therefore, it has the effect of producing a cordierite ceramic foam with low pressure loss, strong structure, high quality, and small coefficient of thermal expansion.

[Brief explanation of the drawing]

Fig. 1 is a process diagram of the method for manufacturing a cordierite ceramic foam having a three-dimensional mesh shell structure according to the present invention, Fig. 2 is a cross-sectional view of an example of a centrifugal blower used in the manufacturing process, and Fig. 3 The figure does not show how four three-dimensional reticular porous bodies made of urethane foam to which cordierite slurry is attached are arranged in the rotating container of a centrifugal blower.
The figure is a perspective view of a ceramic porous body having a three-dimensional network cell structure, and FIG. 5 is a partially enlarged view thereof. In the figure 1...Three-dimensional network porous material 2...Solid content is 5
Cordierite slurry of 9.0% by weight 3...Centrifugal blowing off l14...Drying process 5...Solid content is 63.4
Heavy machinery% cordierite slurry 6...Dried culm 7.
... Firing process 8 ... Ceramic porous body Figure 1 CD) (E) (F) (G) (
)-1) (1) (J) (ni) (L
) Figure 2 Figure 4 Figure 4 Procedural amendments 1, Indication of the case 1981 Special revision application No. 109461 2, Name of invention Cordierite ceramic foam tlJ31i method 3, Person making the amendment (!1 and Relationship Patent applicant ↑ Tsu・No. Taito Shihama Address 7800 Mihama, Hitohigashi-cho, Ogasa-gun, Shizuoka Prefecture Name
Ki V Taller Industries Co., Ltd. 71p"i'nA Representative Takeshi 1) Tetsuo (1 other person) 4. Dai Umihito 465 Telephone 052-773-244
96, the entire text of the specification subject to amendment. Description 1, Name of the invention Method for manufacturing cordierite ceramic foam 2, Claims 1) An organic porous body having a three-dimensional network cell structure is immersed in a cordierite slurry composed of predetermined components,]- After the gelite slurry is coated on the surface, centrifugal force is applied to remove excess cordierite slurry, and then the process of drying is repeated several times, followed by sintering at a predetermined temperature. A method for producing cordierite ceramic foam characterized by: 2) The cordierite according to claim 1, wherein the organic porous body having the three-dimensional cell structure i is a urethane foam having continuous pores having a size of 1fflIll to 3mm. Ceramic foam manufacturing method. 3) The cordierite slurry has a chemical composition of powder constituting the slurry of 45 to 55% by weight of silica and 30 to 30% by weight of alumina.
45% by weight of talc or magnesia selected to be 11-16% by weight of magnesia], aluminum hydroxide or alumina, and clay, and an average of this preparation previously calcined at 1350-1450°C. 3. The method for producing a cordierite ceramic foam according to claims 1 and 2, wherein the cordierite ceramic foam has a particle size of 5 to 100 μm (microns). 3. Detailed Description of the Invention The present invention relates to a method for producing a cordierite ceramic foam used as a catalyst carrier for automobile exhaust gas treatment, and more specifically to a cordierite ceramic foam that has excellent thermal shock resistance and low pressure loss. This relates to the foam manufacturing method. The cordierite ceramic film A is made of Nigelrite-based Relamic material and has a three-dimensional network cell structure with internal communication spaces. In recent years, cordierite ceramic foam has been in the spotlight because it is ideal as a catalyst carrier for treating automobile exhaust gas, especially as a carrier for collecting and purifying diesel engine particulates. However, when used in a car, the following important characteristics are required. The first characteristic is excellent thermal shock resistance. This is because the temperature inside the carrier rises to 600 to 800°C or more in a few tens of seconds due to heating by exhaust gas or heat generated by a catalytic reaction, and the outside can withstand a temperature difference of 100 to 300°C. This property is achieved by reducing the coefficient of thermal expansion of the cordierite ceramic film A-film. The next important characteristic is low pressure loss (small pressure loss during circulation). If the catalyst has high pressure loss (high pressure loss during circulation),
Excessive load is placed on the automobile engine, deteriorating fuel efficiency and running performance. In addition, especially when used for collection and purification of devil particulates, the higher the pressure drop, the less particulate matter can be collected. However, the particulates in the catalyst must be combusted in the slot I-ring etc. in a short period of time, which is a fatal drawback. By the way] - Gelite ceramic foam is made from Corjerite] - Foam rubber such as urethane foam that has communicating holes in a slurry made by dispersing powder in water, or IC is made by dipping a plastic foam and forming an IC slurry coating with a certain thickness. By avoiding dry sintering, a cordierite ceramic porous body having almost the same cell structure as the organic foam described above can be produced, but it is extremely difficult to uniformly coat the organic porous body with slurry to a predetermined thickness. However, there is a problem in that the property of reducing pressure loss mentioned above is lost. Conventionally, as a technology to reduce this pressure loss, Japanese Patent Application Laid-Open No. 1987-
No. 67588 proposes a method in which the mesuri part is immersed in Corjelai 1-sludge, covered with the slurry, and then air is blown to remove it. This was difficult because only air was blown into the air, and the pressure loss could not be reduced. In addition, to reduce the viscosity of cordierite slurry while keeping the same solid content so that it is less likely to sludge when coated with cordierite slurry, it is common practice to add alkaline substances such as feldspar, sodium silicate, and sodium hydroxide to the slurry. Although this is known, components other than cordierite remain in the product, which impairs the low coefficient of thermal expansion characteristic of cordierite 1. The present invention is easy to manufacture, has high quality, has excellent thermal shock resistance, and has low loss. That is, the object of the present invention is to provide a method for manufacturing a cordierite ceramic form that covers cordierite I-, which has a small coefficient of thermal expansion, with a material and that can ensure communication holes of a predetermined diameter. The method for producing a ceramic foam made of =1-diI5-I of the present invention involves immersing an organic porous body having a three-dimensional network cell structure in cordierite slurry made of predetermined components.
- After the slurry is coated on the surface of gelite 1, centrifugal force is applied to remove excess =1-gelite slurry, and then it is dried. After repeating the steps of dipping, removing slurry, and drying several times, a predetermined temperature is set. The structure consists of sintering with Next, the present invention will be explained based on embodiments shown in the drawings. First Example First, a process of producing gelite slurry (1) of predetermined components.
). Step (1) (A) 17% by weight of aluminum hydroxide
31% by weight of talcum and 46% by weight of clay were mixed, kneaded, and dried. This is called raw material powder. Next, (B) this raw material powder was fired at 1410° C. for 5 hours, and then ground until the average particle size became 10 μ (microns). The chemical composition of this powder is 51% silica and 3% alumina.
G% and Magnesia 13%, and X-ray diffraction revealed that the crystal system was all cola 1 rye 1-. This powder is called cordierite powder. Next, (C) 10% by weight of cordierite powder and 30% by weight of raw material powder were dispersed in water, and polyvinyl alcohol and a surfactant were added thereto, so that the solid content of each was 59% by weight.
Two types of ]-gelite slurries 2 and 5 were prepared, 0% by weight and 63.4% by weight. Viscosity is 80~100cps each
, 200-230 cps. Next, Step 1 (2) of manufacturing a cordierite ceramic foam using a three-dimensional reticular urethane foam having communicating holes with the cordierite slurry 2 and 5 will be described. First, as shown in Figure 1 (D), it is cylindrical and has a diameter of 1 mm to 3 mm.
mm In this example, a three-dimensional network-like urethane foam 1 having 2 mm communicating holes is coated with cordierite slurry 2 of (E).
immerse it in water to make the slurry 2 adhere to the entire surface. The lower limit of the communicating hole is set to 1 mm because if it is less than 1 mm, clogging tends to occur. After that, as in (F), using centrifugal blower 3, centrifugal force was applied at 250 revolutions per minute for 30 seconds to remove excess slurry 2 (G).
Drying - [Step 4 was performed. Further similar ([), (F)
, (G)] - culm is repeated, then (+-1> immersion step in the slurry 5, blowing off step similar to step (F) using the centrifugal blowing machine 3 of (1), ( J) Drying step 6
This operation was performed twice. As shown above, slurry 2 with a solid content of 63°4% is used twice, slurry 5e with a solid content of 59.0% is added twice, and a further two times
+ After repeating immersion, blowing off, and drying 4 times, (K)
[Calcination at 1400° C. for 5 hrs] L culm 6 was performed to obtain product 8 with a high density of 0.3 g/cc. By repeating immersion, blowing off, and drying several times in the cordierite slurry made of predetermined components as described above, clogging in the three-dimensional communication [1] is prevented and a layer of uniform thickness is formed. It is formed. In addition, as shown in Fig. 2.3, the rotation of the motor 8 which has a soft star function is decelerated to blow off the surplus cordieri of (F) and (I).
1- A predetermined number of three-dimensional reticular porous bodies 1 to which cordierite slurry has been adhered are arranged in a rotating container 9 using a centrifugal blower 3 that rotates the rotating container 9 at reduced speed, and centrifugal force is applied thereto. To remove excess cordierai 1~sludge, it is appropriate to use centrifugal force for materials like the three-dimensional network porous material 1, where the eyes do not pass in a straight line and form communication ports in three-dimensional directions. However, there are some areas that cannot be blown away using conventional methods of blowing compressed air. A second embodiment will be explained. The solid content was 61% by weight in the same manner as in Example 1 except that the Cora light powder was 30% by weight and the raw material powder was 70% by weight.
, 55% by weight two slurries were made. Viscosity is 200~
It was 250 cps and 80-100 CpS. This was further coated with slurry and sintered in the same manner as in the first example to obtain a product with a bulk density of 0.3 o/cc. Next, first to third comparative examples to be compared with the first to third embodiments according to the present invention will be shown in order. 1st Comparative Example A urethane foam 71- having a communicating hole of 2 mm in size was immersed in slurry 2.5 obtained in the same manner as in the first example. The excess slurry was blown off and dried using a Completo IJ--]Nia of J/cm. After repeating this immersion, -I-i no blowing off, and drying operations four times,
After firing at X5hrs, a high density product (0.3g/cco) was obtained. Second Comparative Example Two types of slurry with a solid content of 56% by weight and 53% by weight were prepared in the same manner as in the first example except that the raw material powder was made 100% by weight. Viscosity is 200~250cps and 80~
It was 100 cps. This slurry was coated with J3 three times at 56% by weight and three times at 53% by weight in the same manner as in the first example, and then baked at 1400°C for 5 hours, resulting in a product with a bulk density of 0.30/cc. I got it. Third Comparative Example A slurry having a solid content of 67% by weight was prepared in the same manner as in Example 1, except that the raw material powder was 95% by weight and the feldspar powder was 5% by weight. This slurry, which had a viscosity of 200 to 250 cps, was coated with the slurry four times in the same manner as in Example 1.
After firing at 360°C for 5 hours, 1q of product has a bulk density of 0.3g/cc. Table 1 shows the characteristics when the above-mentioned Example 1.2 and Comparative Example 1.2.3 were carried out using a carrier having a diameter of 93 mm and a height of 66 mm. Table 1 As shown in Table 1 above, the slurry components in the first sample of the present invention.
The firing temperature was also the same as or equivalent to Example 2.
In the first comparative example, the temperature was the same as in the example, 1400°C (supposed to be the best for cordierite production), and the excess slurry was blown away with compressed air, and in the first comparative example, the solid content of the slurry was 100% by weight of the raw material powder. is the same as that of the first embodiment of the present invention, and in the first to second comparative examples, the pressure loss was significantly large, and the solid content of the slurry was 95% by weight of the raw material powder, 5% by weight of the feldspar powder, and the firing temperature was 1350%. In the third comparative example, which was set at .degree. C. and was otherwise the same as the first embodiment of the present invention, the coefficient of thermal expansion was large, and therefore it was susceptible to thermal shock. As described above, the method for producing gelite ceramics A according to the present invention involves immersing an organic porous body having a three-dimensional network cell structure in Cordierite I slurry made of predetermined components. After the slurry is coated on the surface, centrifugal force is applied to remove excess cordierai slurry, and then it is dried. Steps 1 of immersion, slurry removal, and drying are repeated several times, and then sintered at a predetermined temperature. It is easy to manufacture because it is manufactured by direct coating using the structure of a three-dimensional network-like organic porous material. As a shaped wall is secured, the pressure drop is low, the structure is strong and high quality, and a sufficient amount of cordierite with a small coefficient of thermal expansion is produced, resulting in excellent thermal shock resistance] - The effect of being able to manufacture gelite ceramic foam has. 4. Brief explanation of the drawings Figure 1 is a process diagram of the method for manufacturing a cordierite ceramic foam having a three-dimensional mesh shell structure according to the present invention, and Figure 2 is an example of a centrifugal blower used in the manufacturing process. Figure 3 is a diagram showing a cross section, and Figure 3 is a diagram showing an IC-like structure in which four three-dimensional reticular porous bodies made of urethane foam with cordierite slurry attached are arranged in a rotating container of a centrifugal blower, and Figure 4 is a diagram depicting an IC. FIG. 5 is a perspective view of a ceramic porous body having an original network cell structure, and FIG. 5 is a partially enlarged view thereof. In the figure 1...Three-dimensional network porous material 2...Solid content is 5
9.0% by weight cordierite slurry 3...Centrifugal blower 4...Drying process 5...Solid content is 63.4
ii 1% cordierite slurry 6...Dried Culm 7
... Firing process 8 ... Ceramic porous body

Claims (1)

[Claims] 1) An organic porous body having a three-dimensional network cell structure is immersed in cordierite slurry composed of predetermined components, the cordierite slurry is coated on the surface, and centrifugal force is applied. A method for producing a cordierite ceramic foam, which comprises removing excess cordierite slurry and then drying the foam, repeating the steps of dipping, blowing off, and drying several times, and then sintering at a predetermined temperature. 2) The cordierite ceramic according to claim 1, wherein the organic porous body having a three-dimensional network cell structure is a urethane foam having continuous pores with a size of 1 to 3 mm. Form manufacturing method. 3) The cordierite slurry has a chemical composition of powder constituting the slurry of 45 to 55% by weight of silica and 30 to 30% by weight of alumina.
A mixture of talc or magnesite, aluminum hydroxide or alumino, and clay selected to have a concentration of 45% by weight, 11 to 16% by weight of magnesia, and an average grain obtained by pre-calcining this mixture at 1350 to 1450°C. The method for manufacturing a cordierite ceramic foam according to claims 1 and 2, characterized in that the cordierite ceramic foam is made of cordierite powder having a diameter of 5 to 100 μm (microns).