KR101234445B1 - Ceramic filter composition for purifying exhaust gas and manufacturing method of ceramic honeycomb filter - Google Patents

Abstract

The present invention relates to a composition of a ceramic filter for exhaust gas purification and a method for manufacturing a ceramic honeycomb filter, which can be calcined at low temperature, has excellent thermal shock resistance with low thermal expansion, and improves porosity to effectively remove particulate matter contained in exhaust gas. .

Description

Ceramic filter composition for purifying exhaust gas and manufacturing method of ceramic honeycomb filter

The present invention relates to a composition of a ceramic filter for exhaust gas purification for removing particulates from exhaust gases such as a diesel engine and a method for producing a ceramic honeycomb filter.

Recently, a porous ceramic honeycomb filter has been widely used as an exhaust gas purification technology.

Particles, namely particulate matter contained in the exhaust gas, are formed by forming a porous structure of a honeycomb structure sintered cordierite or pure silicon carbide ceramic and passing the fluid such as exhaust gas including particulate matter. Various filters (Diesel Particulate Filter, DPF) for trapping matter have been put to practical use.

Two problems arise in such a ceramic honeycomb filter. One of the problems is that it is difficult to secure ceramic honeycomb materials that can be fired at low temperatures with excellent thermal shock resistance and high temperature durability of the exhaust gas purification honeycomb filter in harsh environments where the performance of diesel engines is improved and high and low temperatures are repeated. The other is to collect the fine particles by sealing one end face of the flow path partitioned by the partition wall of the ceramic honeycomb and opening the other end face and passing the exhaust gas through the partition wall. Due to the difference in thickness, material, drying process and thermal shock resistance, etc., with the bulkhead of the filter, it is easy to cause cracks or the exhaust gas containing particulates due to dropping due to adhesion instability of this part during the operation of diesel vehicles. There is a problem that occurs.

For example, Korean Patent Publication No. 10-2003-0088047 discloses a plurality of honeycomb filters made of silicon carbide sintered body by mixing, kneading, extruding and drying porous silicon carbide powder and firing in an argon atmosphere at a normal pressure of 2200 ° C. By using a sealing material composed of inorganic binder, organic binder, and inorganic particles to form a single ceramic honeycomb unit by three-dimensionally bonding to reduce the rapid thermal shock resistance generated in diesel engines to increase durability and to obtain a pure silicon carbide honeycomb filter By using this, the thermal conductivity was improved to facilitate the regeneration of the filter.

However, in order to fire the ceramic honeycomb, a special heat treatment device is required for high temperature firing at 2200 ° C., and not only is a high energy process requiring a lot of thermal energy, but also a single filter is used to reduce the thermal shock resistance of the filter. A new process of manufacturing a sealant to separate and bond the unit into two units and bonding the respective filters using the sealant as an adhesive not only reduces cost and productivity, but also prevents gas leakage of the encapsulant layer. For this reason, unnecessary overlap in manufacturing is generated, such as forming an uneven | corrugated prevention layer in the outer peripheral surface of a filter, and it has become a complex increase factor of a cost. This root cause is due to the adoption of silicon carbide (SiC) raw materials for the purpose of thermal conductivity and durability, so that the thermal expansion coefficient of silicon carbide ceramics is not so small as 4.2 × 10 ^-6 K ^-1 . This is because cracking can occur due to thermal stress or thermal shock, which can cause partial damage.

In addition, Korean Patent Publication No. 10-2008-0060221 discloses a method for producing a honeycomb ceramic particle collecting filter carrier, including silicon carbide 1, clay 0.05 to 0.5, cotton powder 0.1 to 0.35, engine oil 0.025 to 0.05, water 0.2 to 0.35 To form a paste, extruding the paste with a dye to form a honeycomb carrier having a cell density of 4 to 62 cells / cm 2, drying at room temperature, and alternating cells at the end faces of the honeycomb carrier. Sealed to form a green ceramic wall flow-type particle collecting filter carrier, and calcined step by step to hold for 0.5 to 12 hours at 1250 ~ 1350 ℃ to prepare a sintered honeycomb particle collecting filter carrier, silicon carbide 1, clay 0.2 ~ A method for producing a honeycomb ceramic particle collecting filter carrier made by attaching a plurality of the above filter carriers with an adhesive composed of 1 and water glass 0.06 to 0.35 has been introduced.

As an inorganic binder of silicon carbide, the sintering temperature of silicon carbide of 2200 ° C or higher was lowered to 1250 ~ 1350 ° C by using clay, and the problem of high temperature sintering was solved. However, 1250 ~ 1350 ° C is referred to as clay sintering temperature. Considering that the coefficient of thermal expansion of the honeycomb-type ceramic particle collecting filter carrier made by the patent is also similar to that of clay, the exhaust gas temperature is rapidly changed from low to high temperature due to the characteristics of the vehicle operation. In this case, there is a possibility that the durability of the honeycomb ceramic particle collecting filter carrier cannot be guaranteed for a long time.

In addition, as a method for forming a seal at one end of a flow path layer formed of a ceramic partition wall, Korean Patent Publication No. 10-2006-0093106 discloses a method for manufacturing a ceramic honeycomb fired body and a sealing material having a porous partition wall, wherein cordierite is a main component. 1 to 40 parts by weight of colloidal silica and 100 parts by weight of colloidal silica to 100 parts by weight of molten silica in the honeycomb fired body obtained by calcining the honeycomb filter to be fired at 1425 ° C. in the composition of the sealing material. 100 parts by weight of cordierite by mixing and adding 1.2 parts by weight of methyl cellulose and water as organic binders to obtain a slurry capable of sealing the ceramic slurry, and then immersing the ceramic Hancomb fired body in the slurry to form a seal. And Comparative Examples 1 to 3 of 50 parts by weight of unfired cordierite powder or 100 parts by weight of unfired cordierite T was compared to the thermal shock resistance. However, in the method of forming a seal, the amorphous oxide matrix composed of the ceramic particles and the colloidal oxide has the advantage of being fired at a low temperature of 1000 ° C. or lower, but compared with the sealant composed of a composition represented by unbaked cordierite. Above 600 ° C, there is a problem that the thermal shock resistance falls.

Patent Publication No. 10-2003-0088047 Patent Publication No. 10-2008-0060221 Patent Publication No. 10-2006-0093106

The present invention for solving the above problems is to provide a composition of the exhaust gas purification ceramic filter capable of low-temperature firing and excellent thermal shock resistance of low thermal expansion and improve the porosity to effectively remove particulate matter contained in the exhaust gas. The purpose.

In addition, the present invention is capable of low-temperature firing, has excellent thermal shock resistance of low thermal expansion, improves the porosity to effectively remove particulate matter contained in the exhaust gas, furthermore, uniformity is generated by thermal stress or thermal shock to partially seal the sealing portion. It is an object of the present invention to provide a method for producing a ceramic honeycomb filter for exhaust gas purification, which can prevent the damage of the scavenger and greatly improve the productivity.

The present invention for achieving the above object,

Provided is a composition of a ceramic filter for exhaust gas purification, comprising cordierite as a main component and comprising anthracite coal ash and a metal oxide as auxiliary components.

The anthracite coal ash preferably contains 3 to 40 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of cordierite.

And the metal oxide is preferably included 0.1 to 5 parts by weight based on 100 parts by weight of cordierite.

The metal oxide is made of Al ₂ O ₃ , SiO ₂ , MgO, BaO, TiO ₂ , ZrO ₂ , Fe ₂ O ₃ and one or two or more selected from the group consisting of aluminosilicate, clay and bentonite are mixed. desirable.

In addition, the present invention,

a) forming a ceramic paste made of a honeycomb-like semi-plastic body having a plurality of cells by mixing water with a ceramic composition containing cordierite as a main component and anthracite coal ash and metal oxide as auxiliary components;

b) mixing water with a ceramic composition containing cordierite as a main component and anthracite coal ash and metal oxide as auxiliary components to obtain a sealant slurry;

c) sealing the cells of the semi-baked body using the sealant slurry;

d) drying and firing the semi-baked body sealed by the sealing material slurry; provides a method for manufacturing a ceramic honeycomb filter for exhaust gas purification, comprising: a.

The anthracite coal ash in the steps a) and b) is 3 to 40 parts by weight based on 100 parts by weight of cordierite, the metal oxide is preferably included 0.1 to 5 parts by weight based on 100 parts by weight of cordierite.

In particular, in the step a), the ceramic composition comprises 3 to 40 parts by weight of anthracite coal ash and 0.1 to 5 parts by weight of metal oxide, in 100 parts by weight of cordierite, and 20 to 30 parts by weight of water in 100 parts by weight of the ceramic composition. It is preferable to form by mixing a part.

And in the step b) the ceramic composition comprises 3 to 40 parts by weight of anthracite coal ash, 0.1 to 5 parts by weight of metal oxide, 100 parts by weight of cordierite, 40 to 80 parts by weight of water to 100 parts by weight of the ceramic composition It is preferable to carry out mixing.

In the step d), the semi-baked body sealed by the sealing material slurry is preferably baked at 1000 to 1200 ° C, and more preferably 0.5 to 1200 to 1400 ° C. by sealing the semi-baked body sealed by the sealing material slurry. It is good to heat up at a rate of -2.0 degreeC / min.

Hereinafter, the composition of the ceramic filter for exhaust gas purification and the manufacturing method of the ceramic honeycomb filter of the present invention will be described in detail.

First, the composition of the ceramic filter for exhaust gas purification of the present invention has a cordierite as a main component, and comprises anthracite coal ash and a metal oxide as auxiliary components. That is, the composition of the ceramic filter of the present invention is characterized in that the cordierite having a low thermal expansion property as a main component, anthracite coal ash having a high temperature refractory properties, and a metal oxide as an inorganic thickener as an auxiliary component.

The anthracite coal ash has a high Al ₂ O ₃ content of 32 to 33 wt%, particularly unburned carbon content of 13 wt% or more, compared to bituminous coal ash as shown in Table 1.

Chemical Composition of Anthracite Coal Fly Ash and Bituminous Coal Fly Ash Fly ash Chemical Content (wt%) Particle Size (㎛) SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO K ₂ O Na ₂ O TiO ₂ MnO P ₂ O ₅ F.C. Anthracite Coal Fly Ash1 52.7 33.5 5.15 1.47 0.87 4.05 0.26 1.73 0.06 0.21 14.4 25.2 Anthracite coal ash2 53.7 32.8 5.10 1.41 0.87 4.22 0.17 1.81 0.05 0.21 13.5 27.3 Bituminous coal ash 1 69.7 18.4 7.0 2.05 0.39 0.72 0.49 1.30 0.03 0.15 1.8 18.27 Bituminous coal ash 2 61.5 25.5 3.8 3.93 1.17 1.16 1.32 1.59 0.05 0.11 2.0 19.99

In addition, as shown in the X-ray diffraction analysis results of FIG. 1 (A: anthracite coalification and B: bituminous coal ash) showing the change in crystal structure of anthracite coal ash and bituminous coal ash at high temperature firing, as the heat treatment temperature increases, The diffraction peak intensity increases, and the diffraction peak intensity of the quartz tends to decrease. In the case of the sample heat-treated at 1300 ° C., the X-ray peak of quartz was almost disappeared, and only the X-ray diffraction peak of mullite was observed. As the heat treatment temperature increases, SiO ₂ component in coal ash reacts with Al ₂ O ₃ component to form mullite. For this reason, the anthracite coal ash shows high fire resistance at high temperature of 1300 degreeC or more. Therefore, anthracite coal ash is a material having excellent high temperature characteristics and is a useful material that can achieve economical purposes such as resource recycling and a reduction in manufacturing cost as an auxiliary raw material of ceramic honeycomb filters.

The anthracite coal ash, in addition to the advantage of increasing the high temperature characteristics by forming a mullite at a temperature of 1300 ℃ or more, as described above, because the unburned carbon contains 13wt% or more 6 ~ 7 times higher than bituminous coal ash, it is a ceramic honeycomb filter As the micro voids are formed during firing, the secondary effect of increasing porosity and unburned carbon acts as exothermic energy and lowers the firing temperature.

The anthracite coal ash is suitable for 3 to 40 parts by weight to 100 parts by weight of cordierite, and when added to less than 3 parts by weight, the effects of high temperature characteristics of anthracite coal ash, resource utilization and porosity improvement, and improvement of extrusion characteristics are weak. When the amount is added in an amount greater than the weight part, the plasticity of the molding raw material is lowered, making it difficult to extrude, and the shrinkage rate is increased, which is disadvantageous. In particular, in order to further improve porosity and formability, it is more preferable to mix 10-20 parts by weight of anthracite coal ash based on 100 parts by weight of cordierite.

The metal oxide is intended to enhance plasticity during extrusion of the green body. The metal oxide may be used in combination with any one or two or more selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, BaO, TiO ₂ , ZrO ₂ , Fe ₂ O _3, and aluminosilicate, clay, and bentonite. In particular, the metal oxide is preferably mixed 0.1 to 5 parts by weight based on 100 parts by weight of cordierite. If the amount is less than 0.1 parts by weight, the addition of inorganic thickeners does not appear, and when mixed with more than 5 parts by weight, there is a problem of lowering plasticity during green body extrusion of the mixed raw materials.

A ceramic honeycomb filter is manufactured using such a composition (hereinafter, referred to as a "ceramic composition") of the purification ceramic filter for exhaust gas.

That is, using a ceramic composition comprising cordierite, anthracite coal ash, and a metal oxide, a honeycomb-like semi-plastic body and a sealing material slurry having a plurality of cells are prepared, and the cells of the semi-plastic body are sealed with the sealing material slurry. After drying and firing to prepare a ceramic honeycomb filter.

First, the semi-plastic body is made of ceramic paste by mixing and kneading the thixotropic thickener, lubricant, antifoaming agent, dispersant, and water together in the ceramic composition, and the ceramic paste is a honeycomb-shaped green body having a plurality of cells through a vacuum extruder. After molding, it is dried and semi-baked.

At this time, the anthracite coal ash may be subjected to a pretreatment process such as iron removal and powdering.

The ceramic composition consisting of a mixture of cordierite, anthracite coal ash and a metal oxide is dry ball milled and then mixed and kneaded with a thixotropic thickener and water. The thixotropic thickener includes methyl cellulose, polyacrylic resin, polyester resin and the like.

At this time, it is preferable to mix 1 to 10 parts by weight of thixotropic thickener and 20 to 30 parts by weight of water based on 100 parts by weight of the ceramic composition. If the thixotropic thickener is mixed in less than 1 part by weight, the thixotropic thickener does not appear to have an additive effect. If the thixotropic thickener is mixed in excess of 10 parts by weight, the strength of the green body may be lowered during extrusion of the mixed raw material.

The ceramic paste is formed into a honeycomb-shaped green body having a plurality of cells through a vacuum extruder after a aging period for a uniform homogenization. The ceramic paste is molded into a green body through an extruder, followed by natural drying, hot air drying, and semi-firing to produce a semi-fired body. Natural drying is to be left in the atmosphere for more than 12 hours, hot air drying can be completed in 6 to 12 hours at 50 ~ 80 ℃. The hot-air dried green body is maintained in a oxidizing atmosphere or a reducing atmosphere such as the presence of an inert gas in an electric furnace or the like at a temperature of 1000 to 1200 ° C. for at least 30 minutes to make a semi-plastic body.

The reason why the green body is semi-baked is that if the green body is not semi-baked, the thickening effect of the thixotropic thickener and the strength of the green body due to drying are absorbed into the partition wall by the moisture of the sealing material slurry, resulting in deformation of the green body. This is because cracks are generated in the deformed or deformed parts of the green body during redrying. The quasi-fired temperature is preferably 1000 to 1200 ° C., and lower than 1000 ° C., the ceramic honeycomb filter is weak in workability, and higher than 1200 ° C. consumes unnecessary thermal energy.

The sealing material slurry is for sealing a cell of a part of a plurality of cells of the semi-baked body, and is made of the same material as the semi-baked body. This is because the thermal expansion coefficient of the semi-plastic body and the sealing part can be the same, so that the difference in the thermal expansion coefficient between the sealing part and the semi-plastic body can be minimized.

Therefore, the sealant slurry is made by mixing a thixotropic thickener, an antifoaming agent, a dispersant, and water in a ceramic composition including cordierite as a main component and anthracite coal ash and metal oxide as auxiliary components. At this time, 1 to 10 parts by weight of thixotropic thickener and 40 to 80 parts by weight of water are preferably mixed with 100 parts by weight of cordierite. And a small amount of dispersant, wetting agent and defoamer are mixed in the sealing material slurry.

It has a viscosity of slurry suitable for sealing operation when 40 to 80 parts by weight of water is mixed.

As the thixotropic thickener, methyl cellulose, polyacrylic resin, polyester resin, and the like may be used, and among them, it is preferable to use polyacrylic resin or polyester resin in view of workability. This is not a sudden thickening effect when the polyester resin or polyester resin is reacted with water, but gradually increases with the amount of the resin, while a thickener such as methyl cellulose rapidly thickens as the content increases. Because is increased.

Next, the cell of the semi-baked body is sealed using the sealant slurry. At this time, the sealing method is not largely limited. For example, the semi-baked body may be immersed in the sealing material slurry for a predetermined time to seal the cell of the semi-baked body to a certain thickness and then dried to seal. In addition, before the sub-plastic body is immersed in the sealing material slurry, it is adhered to the end by using an adhesive film or a resin mask in which mosaic-shaped openings and sealing parts are alternately arranged at both ends of the semi-plastic body, and then immersed in the sealing material slurry. It can also be sealed. And after sealing both ends with a sealing material slurry without using an adhesive film or a resin mask, a mosaic type opening can be formed in the form of digging a needle-shaped coating.

At this time, 1-10 mm is preferable and, as for the thickness of a sealing part, 3-8 mm is more preferable. The thickness of the seal is not particularly limited, and an appropriate thickness may be selected in consideration of the workability of the sealant slurry. If the thickness of the seal is too thick, cracks may occur or be locally deformed due to the difference in residual stress as compared with the thin thickness of the partition wall during drying or firing. Anthracite coal ash is mostly transformed into mullite during the high temperature treatment process, and it has good slurry workability as well as good dryness or plastic shrinkage due to residual unburned carbon (13wt%). There is almost no crack.

Next, when the semi-baked body sealed by the sealing material slurry is dried and fired, a ceramic honeycomb filter for exhaust gas purification is completed.

At this time, the calcination temperature is 1200 to 1400 ° C, particularly 1200 ° C to 1300 ° C. Since the anthracite coal ash is included as an auxiliary component in the sealant slurry and the semi-baked body, sufficient practical strength can be obtained without unnecessary high temperature baking of 1450 ° C or higher. Furthermore, the semi-plastic body sealed by the sealant slurry may be fired in a reducing atmosphere such as an oxidative atmosphere in the air or an inert atmosphere such as nitrogen or argon gas. In particular, in consideration of cost and the like, it is more economic to fire in an oxidizing atmosphere. In addition, since the ceramic honeycomb filter is manufactured by using the sealing material slurry as the main component of the semi-baked body, that is, cordierite as the main component and anthracite coal ash as an auxiliary component, the bonding strength due to the firing of the body and the sealing part is excellent and high strength is achieved. It has the advantage of low thermal expansion and there is almost no plastic shrinkage and crack generation.

3 is a schematic diagram showing the shape of a ceramic honeycomb filter to which the present invention can be applied, and FIG. 4 is a cross-sectional view showing a model when exhaust gas passes through the ceramic honeycomb filter of FIG. 3. The ceramic honeycomb filter 1 has an outer circumferential wall 2 and a porous partition 2a therein, and seals 3 for sealing one opening end of the flow path 4 partitioned by the porous partitions 2 and 2a. ) And the flow path 4 at which the opposite end of the opening is opened are arranged so as to be regularly arranged like a mosaic pattern. The ceramic honeycomb filter 1 is surrounded by a ceramic fiber having elasticity, not shown, and sealed by a metal container. The exhaust gas 5 containing particulate matter flows into the flow passage 4 from the open end on the inflow side, passes through the porous partitions 2 and 2a, and then passes through the adjacent flow path 4 to the open end on the outflow side. Is discharged as purge gas 5a. When passing through the porous partitions 2 and 2a, the particulate matter trapped in the exhaust gas 5 is collected in the pores of the porous partitions 2 and 2a, so that the ceramic honeycomb filter 1 functions as an exhaust gas purification filter. .

The average porosity of the ceramic honeycomb filter is 30 to 65%, preferably 40 to 55%. If the porosity is less than 30%, the pressure of the exhaust gas is increased to cause side effects such as a decrease in engine output. If the porosity is higher than 65%, the honeycomb filter's strength decreases and the particulate collecting efficiency decreases.

The average pore diameter of the ceramic honeycomb filter is 0.5 to 40 µm, preferably 1 to 20 µm. When the average pore diameter is 0.5 μm or less, the filter pore clogging phenomenon increases, and when the average pore diameter is 40 μm or more, the collection performance of the fine particles is reduced.

The thermal expansion coefficient of the ceramic honeycomb filter is preferably 2.5 × 10 ⁻⁶ K ⁻¹ or less. In terms of thermal shock resistance, especially in internal combustion engines such as diesel engines, engine output fluctuates depending on operating conditions, so the flue-gas temperature fluctuates significantly at high and low temperatures. The lower the coefficient of thermal expansion, the better.

In the ceramic honeycomb filter of the present invention, when the collected fine particles accumulate in the partition wall after a certain time, the pores of the filter are closed and the function of the filter is reduced, so that the fine particles are periodically heated by heating means such as a heater. By burning, the function of the filter is regenerated. In this case, when the honeycomb filter is carrying a metal component having catalytic performance, the exhaust gas or the like can be purified or the regeneration temperature of the particulate matter can be reduced. It is preferable that the above-mentioned metal component contains at least one metal component of Pt, Pd, Rh, Ba, K, Sr, La, Ce.

According to the present invention, as a main component of cordierite and anthracite coal ash as auxiliary components, diesel having excellent thermal shock resistance with low thermal expansion at a temperature of 1400 ° C. or less without high temperature firing of 1600 ° C. or more, such as conventional silicon carbide An economical ceramic honeycomb filter capable of removing particulate matter of the internal combustion engine can be manufactured, and the honeycomb-shaped compression characteristics are excellent, thereby improving productivity and reducing extrusion failure rate.

In particular, by using anthracite coal ash, which is a raw material for recycling resources, as an auxiliary material, it is possible to improve the strength and porosity of the honeycomb, and to reduce the manufacturing cost, such as saving the firing energy due to the exothermic characteristics of the unburned carbon powder.

In addition, the present invention uses the sealing material slurry forming the semi-baked body and the sealing portion as the same composition, that is, cordierite as a main component and anthracite coal ash as an auxiliary component, so that the sealing portion can be firmly adhered to the body, and thermal stress or thermal shock can be achieved. This prevents cracks from occurring and prevents the seal from being partially broken, and thus has excellent mechanical properties.

1 is a view showing the crystal structure change of anthracite coal ash and bituminous coal ash at high temperature firing,
2 is a photograph of a scanning electron microscope of anthracite coal ash.
3 is a schematic diagram of the ceramic honeycomb filter of the present invention,
4 is a schematic view showing a cross section and a structure of a ceramic honeycomb filter of the present invention.
5 is a pore size distribution of the ceramic filter of Example 3,
6 is a pore size distribution diagram of the ceramic filter of Comparative Example 1. FIG.
7 is a system diagram of a smoke reduction performance evaluation device of the ceramic honeycomb filter of the present invention.
8 is a photograph taken the ceramic honeycomb filter of the present invention,
9 is a photograph of a ceramic filter after the end of the smoke reduction performance test.

Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

(Ceramic composition)

After mixing 100 parts by weight of the average particle size of DY CERAMICS and 2 parts by weight of calcined cordierite, 10 parts by weight of anthracite coal ash having an average particle size of 27.4 μm, and 0.2 parts by weight of SUMITOMO's average particle size of 45 μm α-alumina as a metal oxide Put into a ball mill dry grinding and mixing for 10 hours to obtain a ceramic composition.

(Manufacture of semiplastic bodies)

9.2 parts by weight of thixotropic thickener, 1.9 parts by weight of lubricant, 0.3 parts by weight of antifoam, 0.3 parts by weight of dispersant, and 20 parts by weight of water were added to a mixer, left to stand for at least 12 hours, and then mixed with the ceramic composition. After mixing for 1 hour using a ribbon mixer was put in the extruder and kneaded 2 to 3 times and left in a sealed state for more than 12 hours to prepare a ceramic paste for extrusion. At this time, as a thixotropic thickener, methyl cellulose, polyacrylic resin, and polyethylene glycol of Samsung Fine Chemicals were used in a ratio of 2: 1: 2. Lubricant used LU-64 by SANNOP.

The ceramic paste was extruded by attaching a honeycomb mold to a vacuum extrusion molding machine to make a honeycomb-shaped ceramic green body, which was naturally dried for at least 12 hours, and then dried by hot air at a temperature of 50 to 80 ° C. The green body was placed in an electric furnace and gradually heated up at a temperature increase rate of 0.5 to 2 ° C./min until reaching 1150 ° C. temperature, and maintained at 1150 ° C. for at least 30 minutes to obtain a honeycomb-type ceramic semi-plastic body.

The quasi-plastic bodies were 62 x 62 mm in width x length, respectively, and cut to 86 mm in length.

(Manufacture of sealing material slurry)

6 parts by weight of thixotropic thickener, 0.5 parts by weight of dispersant, 0.5 parts by weight of antifoaming agent and 40 parts by weight of water were added to a mixer, mixed for 30 minutes or more, and left for 12 hours or more to prepare a sealing material slurry.

(Manufacture of Ceramic Honeycomb Filter)

After one end of the semi-plastic body is immersed in the sealant slurry, the excess slurry is removed, and the slurry is left in the air for a period of time where no flow of the slurry occurs, and then placed in an oven and dried at a temperature of 50 to 80 ° C. for at least 6 hours. I was. The opposite end of the semi-plastic body was also sealed in the same manner as above.

Then, a needle pin having a plurality of needles having a predetermined length was made and inserted into the honeycomb seal to remove unnecessary seals to form mosaic-patterned openings, and the opposite end also formed an asymmetric opening in this manner.

The sealed semi-baked body was placed in an electric furnace and gradually heated up at a temperature increase rate of 0.5 to 2 ° C./min until reaching a temperature of 1250 ° C., and maintained at 1250 ° C. for at least 30 minutes to obtain a final ceramic honeycomb filter.

EXAMPLES 2-4

Unlike Example 1, a ceramic honeycomb filter was manufactured using a ceramic composition obtained by mixing 20 parts by weight, 30 parts by weight, and 40 parts by weight of anthracite coal ash based on 100 parts by weight of cordierite. Meanwhile, in the case of the ceramic composition in which 20 parts by weight of anthracite coal ash was mixed, 30 parts by weight of water was mixed with respect to 100 parts by weight of the ceramic composition to prepare a ceramic paste.

[Example 5]

Unlike Example 1, a ceramic honeycomb filter was manufactured using a ceramic composition obtained by mixing 5 parts by weight of α-alumina with respect to 100 parts by weight of cordierite.

[Comparative Example]

The average particle size of DY CERAMICS Co., Ltd. was prepared by mixing 100 parts by weight of calcined cordierite and 0.2 parts by weight of SUMITOMO's average particle size of 45 μm α-alumina as a metal oxide, followed by dry grinding and mixing for 10 hours to obtain a ceramic composition.

A ceramic honeycomb filter was manufactured in the same manner as in Example 1 using the ceramic composition.

The coefficient of thermal expansion, compressive strength, and porosity of the ceramic honeycomb filters of Examples 1 to 5 and the ceramic honeycomb filters of Comparative Example 1 were measured, and the results are shown in Table 2. The coefficient of thermal expansion was measured using a dilator, the compressive strength was measured using a model US-5884 universal testing machine of Instron Co., and the porosity was measured using a Mercury Porosimeter of Micromeritics Co.

Thermal expansion coefficient, compressive strength and porosity measurement results Compressive strength
(kg / cm ² ) Porosity
(%) Thermal expansion coefficient
(1 / K) Example 1 30 48.8 1.53 × 10 ^-6 Example 2 41 57.1 1.66 × 10 ^-6 Example 3 72 61.2 1.75 × 10 ^-6 Example 4 81 59.5 1.79 × 10 ^-6 Example 5 32 52.1 1.52 × 10 ^-6 Comparative Example 1 25 48.7 1.35 × 10 ^-6

As shown in Table 2, in Comparative Example 1, the compressive strength was low as 25kg / cm ² , but in Examples 1 to 5, the compressive strengths were all excellent at 30kg / cm ² or more. In addition, the porosity was excellent at 48.8% or more.

In particular, as shown in the pore distribution diagrams of Examples 3 and Comparative Examples 1 of FIGS. 5 and 6, Comparative Example 1 has one kind of 3 μm, whereas Example 3 has two kinds of pore sizes of 3 μm and 7 μm. In particular, 7 micron pore content increased due to the unburned carbon of anthracite coal ash.

Next, the shrinkage ratios of Example 2, Example 4 and Comparative Example 1 were measured, and the results are shown in Table 3. Shrinkage was measured by measuring the width and length of the ceramic filter before and after firing directly.

Shrinkage rate measurement result Example 2 Example 4 Comparative Example 1 Firing temperature (캜) 1250 1250 1250 Shrinkage 1 (%) 7.8 10.5 6.5 Shrinkage 2 (%) 7.1 10.9 5.0

As shown in Table 3, the shrinkage ratios of Examples 2 and 3 were measured to be lower than 10.9%.

And the PM removal rate was measured over 3 times using the ceramic honeycomb filter of Example 2, and the result is shown in Table 4. Figure 7 shows a schematic diagram of an evaluation device for measuring the PM removal rate, Figure 8 is a photograph showing the ceramic honeycomb filter of Example 2, Figure 9 is a ceramic honeycomb disassembled the device after the test on the PM removal rate A picture taken with a filter.

PM removal rate measurement result of ceramic No filter filter mounted Reduction performance (%) Primary 20.1 5.9 70.6 Secondary 25.8 7.2 72.1 Third 18.8 4.6 75.5

As shown in the PM removal rate measurement results of Table 4, the PM honey removal rate of the ceramic honeycomb filter of Example 2 was very excellent, which is 70.6% or more.

1: ceramic honeycomb filter, 2: outer wall,
2a: porous bulkhead, 3: seal,
4: euro, 5: exhaust gas,
5a: purifying gas, 6. diesel engine,
7. thermocouple-1, 8.pressure gage-1,
9.Heater, 10. thermocouple-2,
Ceramic Honeycomb Filter, 12.Pressure gage-2,
13. Smoke analyzer, 14. Front exhaust pipe,
15. Rear exhaust pipe, 16. Honeycomb container,
17.Electric Controller

Claims (13)

It is composed of cordierite as a main component, anthracite coal ash and metal oxide as auxiliary components,
10 to 20 parts by weight of anthracite coal ash and 0.1 to 5 parts by weight of a metal oxide are included in 100 parts by weight of the cordierite, the composition of the ceramic filter for exhaust gas purification.
The method of claim 1,
The metal oxide is made of Al ₂ O ₃ , SiO ₂ , MgO, BaO, TiO ₂ , ZrO ₂ , Fe ₂ O ₃ and any one or two or more selected from the group consisting of aluminosilicate, clay and bentonite are mixed. A composition of a ceramic filter for purification of exhaust gas.
a) A ceramic paste formed by mixing water with a ceramic composition comprising 10 to 20 parts by weight of anthracite coal ash and 0.1 to 5 parts by weight of metal oxide in 100 parts by weight of cordierite into a honeycomb-like semi-plastic body having a plurality of cells. After the semi-baking at 1000 ~ 1200 ℃ to obtain a semi-baked body;
b) obtaining a ceramic composition comprising 3 to 40 parts by weight of anthracite coal ash and 0.1 to 5 parts by weight of metal oxide, and then mixing 40 to 80 parts by weight of water to 100 parts by weight of cordierite to obtain a sealing material slurry. Wow;
c) sealing the cells of the semi-baked body using the sealant slurry;
d) drying the calcined body sealed by the sealing material slurry and firing at 1200 to 1400 ° C .; a method of manufacturing a ceramic honeycomb filter for exhaust gas purification comprising: a.
The method of claim 3,
The step d) is a method for producing a ceramic honeycomb filter for exhaust gas purification, characterized in that for heating the semi-baked body sealed by the sealing material slurry at a rate of 0.5 ~ 2.0 ℃ / min to 1200 ~ 1400 ℃. delete delete delete delete delete delete delete delete delete

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