JP3175785B2 - Raw material for forming cordierite ceramics and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of producing cordierite ceramics filter, porous cordierite porous method for manufacturing a ceramic filter used in particular in the exhaust gas purifying apparatus of a diesel vehicle, and cordierite quality Sera
Mix production material .

[0002]

Purifying device of the prior art exhaust gas, in particular heat resistance as the ceramic filter used in purifying apparatus for diesel vehicles withstand particularly rapid temperature increase, and the charge amount against mechanical impact such as vibration I have to endure.

[0003] Further, it is required to efficiently capture dust represented by unburned carbon contained in exhaust gas.
A porous cordierite ceramic mix is known as a material meeting the above conditions.

[0004] By the way, such porous cordierite material
Ceramics require a specific average pore diameter and porosity to efficiently capture dust, which must not change at high temperatures. Conventionally, porous cordierite ceramics
Since the filter using the filter shrank during firing, it deformed and cracked during firing. In addition, the average pore diameter or a vapor <br/> Anaritsu was Tsu or relatively small.

[0005]

On the other hand, as a means for relatively increasing the average pore diameter and porosity, kyanite is blended with cordierite to form a porous cordierite ceramic.
It is known to manufacture a box (Japanese Patent Publication No. Sho 62-4).
2880 publication). In this method, cordierite is made porous, and the pore size is set so that 20% or more of the pores in the fired body have pores having a pore diameter larger than 10 μm.
This is to control the distribution and improve the porosity.

That is, the composition of cordierite of 35 to
45% by weight calcined talc, 30-45% by weight clay and 1
Among 5 to 25% by weight of alumina, the same amount of kyanite is used instead of clay.

However, the cordierite ceramics produced in this manner have an average pore diameter of 10
Although large as μm or more, upon firing deformation is large, a relatively low strength, there is a disadvantage have cracks easy to mechanical shocks.

[0008]

SUMMARY OF THE INVENTION The present invention has a strong strength against heat and machine械的impact, moreover than those having an average pore diameter and porosity conventional cordierite ceramics As a result of various studies and studies for the purpose of increasing the size, the use amount of kyanite was increased from the conventional one.

[0009] Simultaneously mullite may also be used in place of kyanite, in the present invention, kyanite and / or mullite co Jieraito ceramics produced Hara
Fee to, Ru using 46-65 wt%.

[0010] Thus, the present invention is, kyanite and / or <br/> is mullite DOO 4 6-65 wt%, silica (provided that the chi
(Excluding those contained in yanite and / or mullite) 22
~ 40% by weight, alumina (however, the above kyanite and
And / or excluding mullite) 0-12% by weight,
That provides a magnesia 11 to 16% by weight Tona Turkey Jieraito ceramics produced raw materials. Also, the above Kojie
A sintering aid is further added to the raw material for the production of light ceramics.
Sintering aid containing cordierite ceramics
Provide raw materials. In addition, the cordierite-based ceramics
Raw material or cordierite containing sintering aid
The ceramic forming raw material is heated at 1350-1440 ° C. for 0.1 hour.
Cordierite characterized by firing for 1 to 24 hours
Provided is a method for manufacturing a porous ceramic filter .

[0011] The amount of kyanite and / or mullite in the present invention, co Jieraito ceramics produced
Raw materials (hereinafter referred to as cordierite raw materials)
~ 65 % by weight. The amount used is less than 46% by weight kyanite also increases the raw material other than mullite, calcined or shrinkage is increased, it becomes difficult to control the porosity or the average pore diameter is greater than 65 wt% in the reverse In this case, the composition deviates from the cordierite composition, and the coefficient of thermal expansion becomes high . Less sintering deformation when adopting a 46-57 wt% with respect to co Jieraito material, close to the theoretical composition of cordierite is particularly preferable because the thermal expansion coefficient is low.

The particle size of the kyanite used in the present invention is suitably from 15 to 149 μm in terms of the maximum particle diameter. The average pore diameter in the case of the maximum particle diameter is less than 15μm is less than 8 [mu] m, 149 .mu.m conversely
Also undesirable Re Izu since so that the unreacted mullite remain on the particle center of kyanite if exceeded. If the maximum particle diameter of Ru 30~74μm der an average pore diameter is particularly preferred because unreacted mullite is 5 wt% or less at 10 to 30 [mu] m.

Further, in the case of using mullite, the maximum particle diameter it is appropriate to Ru 20~149μm der.
The average pore straight if the maximum particle diameter is less than 20μm
If the diameter becomes smaller than 5 μm and exceeds 149 μm, unreacted mullite will remain in the center of the particle.
Nor any undesirable. The maximum particle diameter is 35~74μm
If Der Ru has an average pore diameter is particularly preferred because unreacted mullite is 5 wt% or less at 10 to 30 [mu] m.

[0014] kyanite their case together with mullite
The amount becomes 46 to 65% by weight based on the cordierite raw material.
Any ratio can be used within the range . The proportion, the former is 80 to 90 wt%, the latter is 20 to 10 wt%
A particularly preferred because it reduces the sintering deformation and shall be the.

[0015] Then the amount of put that silica present invention is 22 to 40% by weight relative to cordierite raw material. Use
If the amount of use is less than 22% by weight, it becomes an impurity of spinel occurs, when it exceeds 40 wt% conversely, mullite, enstatite, and the crystalline phases other than cordierite, such as cristobalite occurs This is inappropriate. And for the cordierite raw materials 27-33
The total weight% der Ru and cordierite crystal phase other than the near cordierite theoretical composition of the is 10 wt% or less
Is particularly preferred.

The particle size of the silica used in the present invention, it is appropriate to adopt a 20μm hereinafter in average particle diameter. Unfavorable when the average particle diameter is more than 20μm or remain unreacted silica, since you you experience uneven composition. If the average particle diameter of Ru der less 5μm is unreacted silica it may not remain, particularly preferred since less nonuniformity of the composition.

[0017] then use the amount of put that alumina in the present invention,
It is 0 to 12% by weight with respect to cordierite raw materials. Use
If the dose exceeds 12% by weight , a crystal phase other than cordierite such as spinel will be formed, which is not suitable . Total co Jieraito material to be other than near the 2-5 wt% der Ru and cordierite theoretical composition of cordierite crystal phase is particularly preferred because a 10 wt% or less.

The alumina used in the present invention preferably has an average particle diameter of 20 μm or less.
Unfavorable when the average particle diameter is more than 20μm or remain unreacted alumina, because you you experience uneven composition. If the average particle diameter of Ru der less 5μm is
Unreacted alumina may not remain, <br/> particularly preferred because less nonuniformity of the composition.

[0019] then use the amount of put that magnesia to the present invention
Is Ru Oh <br/> with 11-16% by weight relative to cordierite raw material. If the amount used is less than 11% by weight , a crystal phase other than cordierite such as mullite will be formed,
On the other hand, if it exceeds 16% by weight , a crystal phase other than cordierite such as spinel or enstatite will be formed, which is not suitable . And for co-Jieraito raw materials 1
Total 2-14 wt% der Ru and cordierite crystal phase other than the near cordierite theoretical composition are particularly preferred because a 10 wt% or less.

The particle size of magnesia used in the present invention is as follows:
It is appropriate to adopt an average particle diameter of 10 μm or less. When the average particle diameter exceeds 10 μm , unreacted magnesia remains or the composition becomes non-uniform .
In undesirable. If the average particle diameter of Ru der less 5μm is unreacted magnesia also not remain, particularly preferred since less nonuniformity of the composition.

The koji thus adjusted in particle size and blending amount
Eraito material is calcined by mixing the charge amount, in this case, water and a sintering aid is used. The amount of water used is 3
0 to 50% by weight is suitable. If the amount of water is less than 30 wt%, the viscosity of the raw 坏 soil has high moldability is deteriorated and unfavorable Re Izu so can not be molded low viscosity when it exceeds 50 wt% in the reverse .

On the other hand, as a sintering aid, an alkali metal compound
The object and / or a suitable alkaline earth metal compound. A <br/> alkali metal compound, the alkaline earth metal compound,
For example, hydroxides, oxides, sulfates, alumina compounds, silica compounds and the like can be mentioned . Alkali metal compounds and / or
Or it may be a compound such as 2 or more alkaline earth metal compound is combined.

The alkali metal in the alkali metal compound includes sodium, potassium, lithium and the like .
Examples of the alkaline earth metal in the earth metal compound include mosquito Le <br/> Siumu, barium, magnesium, beryllium and the like.

Specific examples of the sintering aid include soda feldspar, anorthite, and the like. These are preferable in view of the relationship between the melting point of the sintering aid and the sintering temperature described later. The amount of sintering aid used depends on all raw materials except water (that is,
It is appropriate Ru 1 to 30 wt% der in respect the total amount) with the aid. The low intensity when the amount of use is less than 1 wt%, an average pore diameter is reduced, in the case of more than 30 wt% in the reverse is unsuitable because the porosity is 10% or less. With respect to the total raw materials with the exception of water that Ru 1 to 10% by weight der,
Upon intensity is high, the porosity is preferably than 25% to 45% and an average pore diameter becomes 15~30μ m.

In the present invention, the firing conditions are 1350 to 1
It is preferable to employ a temperature of 440 ° C. for 0.1 to 24 hours.
Low or baked formation time than baked formation temperature is 1350 ° C. 0.1
Becomes the unreacted mullite and spinel remains when less than the time, also higher than the tempering formation temperature of 1440 ° C. Conversely
If the burn formation time exceeds 24 hours, or porosity is reduced to cause densification, cordierite decomposed nor any undesirable because mullite occurs with. Further, in the present invention, also some silica and alumina used in the raw material has in exchange cash to all kaolin and other clays, also also some magnesia and silica used as a raw material can be replaced in whole talc.

[0026] cordierite quality obtained by the present invention
The average pore diameter of the ceramic is 5 to 80 μm, especially 1
0-40 μm, the porosity is 20-45%,
Firing shrinkage photon Donaku, also it does not cause even destruction against thermal shock and mechanical shock. Therefore, the ceramic filter according to the present invention, for example, particulate traps and steelworks blast diesel engines, as a filter for various exhaust gas purifying apparatus of a boiler or the like, or useful as a filter during high-temperature sterilization of liquid.

[0027]

Examples (Examples 1 to 9) and Comparative Examples (Example 10) Each raw material of kyanite, mullite, kaolin, talc, alumina, silica and the like shown in Table 1 to synthesize cordierite (in parentheses) Maximum or average particle diameter shown
[Mu] m) a predetermined amount (unit: wt%) were mixed, to this mixture 100 weight%, the weight% of 0, 3, 5 a sintering aid, and water 20 to 35 wt%, cellulose 7 weight units of % was added, after the charge amount kneaded with a kneading machine, and left press <br/> using extruder. Shows a cordierite ceramic scan of characteristics obtained with this extrusion and calcined 5 hours at 1400 ° C. Table 2. The average pore diameter (unit: μm) was measured by a mercury intrusion porosimeter, and the porosity was measured by an Archimedes method. The coefficient of thermal expansion is 25-1
It is an average value at 000 ° C. (unit: 10 ⁻⁷ / ° C.).

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

According to the present invention, the average pore diameter and the porosity of the cordierite -based ceramics are set to values suitable for the filter, and the cordierite has substantially no shrinkage.

[0031]

According to the present invention, the mosquitoes <br/> Iyanaito and / or as a cordierite raw material to identify the amount of mullite. Heat resistance possessed by the cordierite thereby <br/>, withstand charge amount to a particularly rapid heating and mechanical shock. Accordingly, it is optimum as a filter used for an exhaust gas purifying apparatus vibration of an automobile or the like is large, and are exposed to rapid Atsushi Nobori.

Claims (4)

(57) [Claims] [Claim 1] kyanite and / or Murai door 4 6-6
5% by weight, silica (provided that the kyanite and / or
22-40% by weight of aluminum ( excluding that contained in mullite)
Except Murrell min) 0 to 12% by weight, magnesia 11-1
6% by weight Tona Turkey Jieraito ceramics produced original
Fees . 2. The silica or alumina having an average particle diameter of 20
The cordierite-based ceramic forming raw material according to claim 1 , which is not more than μm. 3. Cordierite substance according to claim 1 or 2.
A sintering aid is further added to the ceramic forming raw material
Raw material for producing cordierite ceramics containing sintering aids . 4. A cordiery according to claim 1 or 2.
A raw material for forming a ceramic ceramic or a sintering aid according to claim 3.
The raw material for producing cordierite ceramics containing the
Firing at 50-1440 ° C. for 0.1-24 hours is a special feature.
Of cordierite ceramic filter
Method.