KR100826762B1 - Ceramic filter and Method for preparing the same - Google Patents

Abstract

The present invention includes a ceramic filter and a method for producing the same, and more particularly, a porous ceramic paper including an inorganic fiber having a void, wherein the void is formed by carbonization of an organic component. The present invention relates to a ceramic filter and a method for manufacturing the same, which are capable of maintaining excellent mechanical strength of the ceramic filter while improving the pore uniformity by converting the organic fiber into an inorganic hollow fiber, even after firing.

Ceramic Filter, Manufacturing Method, Pore, Uniformity

Description

Ceramic filter and method for preparing the same {Ceramic filter and Method for preparing the same}

1 is a schematic perspective view of a ceramic filter in the form of a wound honeycomb according to an embodiment of the present invention.

2 is a scanning electron microscope (SEM) photograph of the porous ceramic plate-shaped paper prepared in Example 1 of the present invention.

3 is a SEM photograph of a cross section of an aluminum phosphate hollow fiber present in a porous ceramic paper specimen prepared by coating with an aluminum phosphate coating solution used in Example 1 of the present invention and firing.

4 is a green paper specimen (1) before firing, a porous ceramic paper specimen (2) prepared by coating and firing with an aluminum phosphate coating solution used in Example 9 of the present invention, a porous ceramic paper specimen prepared in Comparative Example 1 For each of the porous ceramic paper specimens 4 prepared in (3) and Comparative Example 2, it is a graph of gas permeability change before and after firing at 1000 ° C.

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<Description of the symbols for the main parts of the drawings>

10 ... ceramic plate paper

20 ... ceramic waveform paper

The present invention relates to a ceramic filter and a method of manufacturing the same, and more particularly, to a ceramic filter having excellent pore uniformity and excellent mechanical strength, and a method of manufacturing the same.

Diesel cars have a higher energy efficiency than gasoline cars and are recognized as being particularly environmentally friendly due to their relatively low emissions of carbon monoxide and hydrocarbons, and their usage has grown rapidly since the mid-80s. However, over the past few years, diesel vehicles have been criticized for their emissions, especially nitrogen oxides and dust, and they have recently solved the air pollution problem due to the increase in the amount of particulate matter (PM) emitted by increasing demand for diesel vehicles. In order to achieve this, countries are implementing strong PM emission standards. Accordingly, the entry of vehicles equipped with soot filtration equipment is emerging as a big issue.

In the late 1970s, a diesel particulate filter (DPF) was proposed and researched as a device for filtering particulate matter from diesel engines. Until 1980, the DPF was installed due to the development of engine design and fuel improvement. Without this, research on the environmental regulations could not be satisfied. However, since 1980, the regulatory standard has been strengthened, and accordingly, research on the DPF has begun to be actively conducted.

Such a DPF must have the ability to trap and remove particles contained in the exhaust gas and to burn off the particles completely before the impact caused by the pressure drop affects the engine and to have high temperature resistance and durability. The DPF can be divided into honeycomb monolith filter, ceramic fiber filter and metal filter. Among these, the honeycomb monolith filter has a disadvantage in that it is vulnerable to high temperature thermal shock and short in life, and the metal filter has a disadvantage in that it is inexpensive to manufacture and easy to manufacture, but has a disadvantage in that heat resistance and corrosion resistance are weak. Research on fiber filters using ceramic fibers has been actively conducted. These ceramic fiber filters are manufactured in the form of foam, extruded article or non-woven paper. The foam and the extruded form are susceptible to thermal shock, and the extruded honeycomb form does not have a large porosity, resulting in low gas permeability. It is known that the nonwoven paper form has high porosity and high particle removal efficiency.

In order to use the nonwoven paper made of ceramic fiber as a filter, the wave form is made in the green paper state through the wave form to increase the surface area within a single volume.In the case of the ceramic paper made of only the ceramic fiber, the paper itself has a tensile force. Due to the small length of the fibers used, structural breakage may occur during the corrugation process. In order to overcome these disadvantages and obtain various ceramic filter types, organic fibers and organic binders may be added to have fluidity and tensile force. Ceramic green paper is manufactured. However, in order to use the ceramic green paper containing the organic fiber at a high temperature, the organic components contained in the ceramic green paper must be finally heat treated to remove the organic components in the ceramic green paper. It becomes difficult to maintain the paper form, and since the organic fibers are left in the place where the position is located, there is a fear that the size of the final pore is uneven and the strength is reduced. For this reason, the amount of use of organic fibers in the prior art is limited, and accordingly, since the fluidity and the tensile force are not maintained after the green paper is manufactured, it is difficult to make the waveform.

In order to improve the above problem, International Patent Publication No. 03/004438 discloses a technical configuration to compensate for the decrease in strength by coating a mixture of silica sol, clay, and inorganic nanoparticles before firing, Therefore, there was a concern that the pores were partially blocked, and there was still a problem due to the change in pore size distribution caused by the removal of the organic fiber.

In addition, US Patent No. 6444006 discloses a technical configuration that prevents a decrease in strength after firing by uniformly depositing SiC precursors on the surface of ceramic paper using chemical vapor deposition and then performing heat treatment. Due to the use of chemical vapor deposition, process efficiency is very low and manufacturing costs are expensive.

Therefore, the first technical problem to be achieved by the present invention is to improve the fluidity and tensile force of the paper in the green paper state by using the organic fiber, while reducing the uniformity of the pores that may be caused by the loss of the organic fiber after firing and It is to provide a ceramic filter having excellent pore uniformity and mechanical strength by minimizing a decrease in the mechanical strength of the paper.

The second technical problem to be achieved by the present invention is to provide a method of manufacturing the ceramic filter.

In order to achieve the first technical problem, according to the present invention,

Provided is a porous ceramic paper comprising an inorganic fiber having voids (hereinafter also referred to as "hollow fiber"), wherein the voids are formed by carbonization of an organic component.

In one embodiment of the ceramic filter of the present invention, the inorganic fiber is characterized in that the aluminum phosphate hollow fiber.

In one embodiment of the ceramic filter of the present invention, the organic component is characterized in that the organic fiber.

In one embodiment of the ceramic filter of the present invention, the structure is a honeycomb structure in which ceramic corrugated paper and ceramic plate-shaped paper are bonded to each other.

In one embodiment of the ceramic filter of the present invention, when the structure is a honeycomb structure in which the ceramic corrugated paper and the ceramic plate paper are bonded, the ceramic corrugated paper and the ceramic plate paper are made of the same material.

In one embodiment of the ceramic filter of the present invention, the bending strength after firing of the ceramic paper is 1.0 MPa or more, and the gas permeability is 10 cc / sec / cm ² It is characterized by the above.

On the other hand, in order to achieve the second technical problem, the present invention

(a) preparing a ceramic green paper using a slurry composition of 0.1-10 mm long ceramic fibers, organic fibers and organic binders;

(b) first drying the ceramic green paper;

(c) fabricating a ceramic filter using the dried ceramic green paper;

(d) coating the ceramic filter with an aluminum phosphate solution; And

(e) preparing a porous ceramic filter comprising drying the ceramic filter coated with the aluminum phosphate solution and baking the same, thereby forming an aluminum phosphate hollow fiber having a void formed in the ceramic filter by carbonizing the organic fiber. Provide a method.

In addition, in order to achieve the second technical problem, the present invention

(a) preparing a ceramic green paper using a slurry composition of 0.1-10 mm long ceramic fibers, organic fibers and organic binders;

(b) first drying the ceramic green paper;

(c) coating the dried ceramic green paper with an aluminum phosphate solution;

(d) carbonizing the organic fiber by drying and firing the ceramic green paper coated with the aluminum phosphate solution to form an aluminum phosphate hollow fiber in the ceramic paper in which voids are formed; And

(e) providing a method of manufacturing a ceramic filter comprising the step of preparing a ceramic filter using ceramic paper including the aluminum phosphate hollow fiber in which the voids are formed.

In one embodiment of the ceramic filter manufacturing method of the present invention, the ceramic fiber is at least one selected from the group consisting of alumina, aluminosilicate, alumino borosilicate, mullite, and mixtures thereof, and the content of the ceramic fiber in the slurry composition The silver slurry is characterized in that 50 to 80% by weight based on the solid content.

In one embodiment of the method of manufacturing a ceramic filter of the present invention, the organic fiber is at least one selected from the group consisting of natural fibers, synthetic fibers, and mixtures thereof, and the content of organic fibers in the slurry composition is 5 to 5 times the ceramic fiber content. It is characterized in that 50% by weight.

In one embodiment of the method of manufacturing a ceramic filter of the present invention, the organic binder is methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, purified starch, dextrin, polyvinyl alcohol, polyvinyl butyral, polymethylmetha. At least one selected from the group consisting of acrylate, polyethylene glycol, paraffin, wax emulsion, microcrystalline wax, and mixtures thereof, wherein the content of the organic binder in the slurry composition is 1 to 20% by weight of the ceramic fiber content.

In one embodiment of the ceramic filter manufacturing method of the present invention, the slurry composition is characterized in that it further comprises a pH adjuster.

In one embodiment of the ceramic filter manufacturing method of the present invention, the pH adjusting agent is characterized in that the ammonium aluminum sulfate.

In one embodiment of the ceramic filter manufacturing method of the present invention, the aluminum phosphate solution is prepared by mixing aluminum hydroxide and phosphoric acid, characterized in that the P / Al atomic ratio in the solution is 3 to 50.

In one embodiment of the ceramic filter manufacturing method of the present invention, the aluminum phosphate solution is characterized in that it further comprises selected from the group consisting of isopropyl alcohol and mixtures thereof as a penetration solvent.

In one embodiment of the ceramic filter manufacturing method of the present invention, the content of the penetration solvent in the aluminum phosphate solution is characterized in that 1 to 30% by weight relative to the water content in the aluminum phosphate solution.

In one embodiment of the ceramic filter manufacturing method of the present invention, the weight of the aluminum phosphate in the aluminum phosphate solution is characterized in that 1 to 80% based on the solids content.

In one embodiment of the ceramic filter manufacturing method of the present invention, the firing temperature is characterized in that 400 to 1100 ℃.

Hereinafter, the present invention will be described in more detail.

According to one embodiment of the invention, the ceramic filter of the present invention comprises a porous ceramic paper comprising an inorganic fiber having pores, preferably an aluminum phosphate hollow fiber, the porous ceramic paper comprising a ceramic fiber, an organic fiber and Ceramic green paper prepared by using a slurry composition including an organic binder is coated with an inorganic binder solution such as aluminum phosphate, and then fired. The pores are formed by carbonization of organic fibers during firing. In particular, when the ceramic filter of the present invention is made of a honeycomb wound filter, sufficient organic fibers are used to perform a smooth wave forming process.

The organic green fibers prepared using the organic fibers are coated with an inorganic binder solution such as aluminum phosphate, for example, to coat organic components (organic fibers and / or organic binders, mainly organic fibers) included in the green paper. By firing this, the organic components (organic fibers and / or organic binders, mainly organic fibers) inside the green paper are carbonized, but the inorganic hollow fiber, in which the external inorganic binder coating layer retains its shape, that is, inorganic fibers having voids Is formed in the ceramic paper constituting the filter. That is, in the present invention, even if the organic fiber is removed from the ceramic filter by firing, since pores similar to the shape are maintained by the newly formed inorganic hollow fiber, irregular pores are prevented from being formed even if the organic fiber is removed during firing. will be. Accordingly, the ceramic filter of the present invention maintains excellent wave form state by using a sufficient amount of organic fibers when manufactured as a wound filter, and at the same time, the organic fibers inside the inorganic binder coating layer are carbonized during firing as described above. Forming the pores and the external inorganic binder is characterized in that the mechanical strength of the ceramic paper and the uniformity of the pores can be improved due to the presence of the inorganic fibers remaining in the form of sintered inorganic layers, that is, inorganic fibers having pores therein. .

The inorganic binder usable in the present invention is not particularly limited as long as the shape of the coating layer may remain as it is during sintering after coating the organic binder, and may be, for example, aluminum phosphate. In this case, the inorganic fiber having voids present in the ceramic filter after firing is an aluminum phosphate hollow fiber.

The ceramic filter according to the present invention may have a simple plate-like structure or may have a honeycomb structure in which ceramic corrugated paper and ceramic plate-shaped paper are bonded to each other. When the structure of the ceramic filter of the present invention is a honeycomb structure in which ceramic corrugated paper and ceramic plate paper are adhered to each other, the ceramic plate paper may be made of the same material as the ceramic corrugated paper, or may be made of a different material. Is made of the same material.

According to a preferred embodiment of the present invention, the bending strength after firing of the ceramic paper used in the ceramic filter is 1.0 MPa or more, and the gas permeability is 10 cc / sec / cm ^2. More preferably 15 cc / sec / cm ² That's it.

In the present invention, the ceramic green paper may be prepared using a papermaking method commonly used in the art, and the slurry composition used is prepared by mixing the ceramic fiber with the organic fiber and a small amount of the organic binder. The ceramic fiber that can be used in the preparation of the slurry composition should be made of a material that can withstand high temperatures of about 1200 ° C. or more, and may include one or more alumina or silica, for example, alumina, alumino silicate, alumino boro. One or more selected from the group consisting of silicates, mullites and mixtures thereof can be used. On the other hand, the ceramic fiber generally has a diameter of 1 to 20 microns and a length of 0.1 to 10 mm, preferably 0.1 to 1 mm can be used, when the length is less than 0.1 mm, the strength of the produced paper is very weak, When it exceeds 10 mm, it is difficult to uniformly disperse the fibers, which may cause unevenness of the paper. In addition, the content of the ceramic fiber in the slurry composition may be 50 to 80% by weight, more preferably 70 to 80% by weight based on solids in the slurry composition. When the content of the ceramic fiber is less than 50% by weight, it may adversely affect the strength and pore characteristics after firing. When the content of the ceramic fiber exceeds 80% by weight, the amount of the organic fiber and the organic binder is too small so that the tensile strength may drop during the corrugation step. There is.

In addition, the slurry composition used in the manufacture of the ceramic green paper in the present invention is preferably a natural fiber such as conifer pulp, wood fiber, hemp; Synthetic fibers such as nylon, rayon, polyester, polypropylene, polyethylene, aramid or acrylic; And it may include one or more organic fibers selected from the group consisting of.

The organic fibers usable in the present invention are preferably natural fibers such as conifer pulp, wood fibers, hemps; Synthetic fibers such as nylon, rayon, polyester, polypropylene, polyethylene, aramid or acrylic; And mixtures thereof. The content of the organic fiber, based on the ceramic fiber, may be 5 to 50% by weight of the ceramic fiber content, more preferably 15 to 25% by weight. When the content of the organic fiber is less than 5% by weight, the tensile strength of the ceramic green paper may be lowered. When the content of the organic fiber exceeds 50% by weight, an excessive amount of aluminum phosphate hollow fiber may be present after firing. There is.

On the other hand, the organic binder usable in the present invention is not particularly limited as long as it is commonly used in the art, for example, methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, purified starch, dextrin, polyvinyl alcohol, polyvinyl One or more selected from the group consisting of butyral, polymethylmethacrylate, polyethylene glycol, paraffin, wax emulsion, microcrystalline wax and mixtures thereof can be used. The content of the organic binder may be 1 to 20% by weight of the ceramic fiber content, based on the ceramic fiber, when less than 1% by weight is not bonded to each other, and when more than 20% by weight of the ceramic Since the fluidity | liquidity of a green paper becomes large unnecessarily and adhesiveness appears, there exists a possibility that workability may fall.

On the other hand, the slurry composition usable in the present invention may be further added a pH adjusting agent to improve the adhesion of the organic binder to the ceramic fiber or organic fiber, such pH adjusting agent is not particularly limited as long as it is commonly used in the art. Can be used, for example, using ammonium aluminum sulfate (alum) to maintain the pH of the slurry composition between 5.5 and 6.5.

The amount of water used in the slurry composition is not critical, and may be just enough to keep the entire process smooth. In order to remove water smoothly in the process, excess water can be removed through a vacuum pump connected to the papermaking device and the excess water can be removed through the press.

The aluminum phosphate solution usable in the present invention is prepared by mixing aluminum hydroxide and phosphoric acid, which aluminum phosphate is used to increase the temperature and structural stability of the ceramic green paper filter structure. The atomic ratio of P / Al in the aluminum phosphate solution may be 3 to 50. When the atomic ratio is less than 3, the solubility of alumina is very low and the formation of aluminum phosphate may not be smooth. Because of the excessive amount, the alumina concentration is low, resulting in poor coatability and damage to the surface of the fiber, thereby weakening the strength.

On the other hand, the phosphoric acid in the role of the carbonization (carbonization) of the organic fiber at a low temperature during firing serves to prevent the combustion is not blown away.

The process for coating the ceramic green paper with the aluminum phosphate solution is not particularly limited, and may be, for example, by impregnation or spraying. Preferably, the aluminum phosphate solution further includes a mixed solvent of water and a penetrating solvent. It is preferable to use one selected from the group consisting of ethanol, isopropyl alcohol, and mixtures thereof. The content of the penetrating solvent is suitably 1 to 30% by weight based on the water content of the aluminum phosphate solution. If the content of the penetrating solvent is less than 1% by weight, the role may not be smooth and may cause precipitation of aluminum phosphate when it exceeds 30% by weight. In addition, the weight of the aluminum phosphate in the total aluminum phosphate solution may be 1 to 80% by weight based on the solid content, if less than 1% by weight it must be repeated several times to coat the required amount, if more than 80% by weight Aluminum phosphate remains between the pores, pore reduction phenomenon and there is a fear that the impact resistance of the paper is reduced.

After drying the green ceramic paper coated with the aluminum phosphate solution, the porous ceramic paper may be manufactured by baking at 400 to 1100 ° C. in vacuum, inert gas or air. When the firing temperature is less than 400 ° C, the organic component is not completely removed. When the firing temperature is above 1100 ° C, the aluminum phosphate may be deformed, leading to a decrease in strength. In the present invention, the aluminum phosphate hollow fiber present in the ceramic filter after firing the ceramic filter is in a form in which two phases of Al (PO ₃ ) ₃ (aluminum metaphosphate) and AlPO ₄ (aluminum orthophosphate) are mixed. It is judged to exist.

On the other hand, the ceramic filter according to the present invention may be produced by coating and firing the ceramic green paper prepared above with an aluminum phosphate solution, and then processing it into a desired form, but when manufacturing in a honeycomb form, the ceramic green paper After the corrugation step, the corrugated ceramic corrugated paper and ceramic plate-shaped paper are adhered to each other to be manufactured in a honeycomb form, and then coated with aluminum phosphate solution and calcined, that is, coated with aluminum phosphate solution. The firing process is preferably performed after the ceramic filter is manufactured in the form of honeycomb. At this time, the waveform can be performed using a waveform device commonly used in the art, for example, the drum of the waveform device that can be used in the present invention, the length of the valley and pitch, 2mm and 3mm, respectively, It is preferable that the surface temperature and the paper feed rate are made to be adjustable.

1 is a schematic perspective view of a honeycomb-type ceramic filter according to an embodiment of the present invention. The ceramic filter as shown in FIG. 1 can be manufactured using the ceramic corrugated paper and the ceramic plate paper prepared as described above. The ceramic plate paper is placed under the ceramic corrugated paper and adhesive is applied to the contact surface. After coating, they are bonded to each other to produce them. The adhesive used in this case is not particularly limited as long as it is conventionally used in the art, and thus, the final ceramic filter is manufactured by winding in a cochlear shape in a state where the upper layer and the lower layer are joined, then coating with an aluminum phosphate coating solution, drying and baking. can do.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited thereto.

Example  One

1- (1) Waveform  Manufacture of Ceramic Green Paper

3 g of alumina-silica fiber having an average length of 300 μm was added to 2000 ml of water, and the mixture was vigorously stirred to disperse the fibers. Then, 5 wt% of coniferous pulp was added to the ceramic fiber as an organic fiber, and then the ceramic paper had flexibility. 10 wt% of the acrylic binder was added to the ceramic fiber, and 5 ml of an aqueous 1% aluminum sulfate solution of pH 3 was added to adjust the pH of the entire slurry composition to about 5.5. Next, the mixture was continuously stirred lightly to uniformly mix the solids in the slurry, and then a ceramic paper having a diameter of 9.5 cm and a thickness of 500 μm was prepared using a papermaking apparatus, and then wave-formed using a wave forming apparatus. Thereafter, the ceramic paper prepared above was naturally dried at room temperature for 30 minutes and then dried in the drying oven at 100 ° C.

Next, using the corrugating apparatus (model name: KIER, manufacturer: Mars apparatus, the length of the valleys and pitch: 2mm and 3mm, respectively) at the feed rate of 2 to 10 m / min at a surface temperature of 150 ℃ The green paper was corrugated.

Preparation of 1- (2) Ceramic Plate Paper

A ceramic plate-like paper was prepared in the same manner as in Example 1- (2) except that the wave was not waved.

1- (3) Winding type  Manufacture of ceramic filters

The ceramic plate-shaped paper was placed on the lower layer of the corrugated ceramic corrugated paper prepared by the above method, and the adhesive was applied to the contact surface, and then bonded to each other. At this time, the adhesive used was starch powder and silica powder was added to enhance the adhesive strength after high temperature heat treatment. As described above, the wound-type ceramic filter was manufactured by winding in a cochlear shape in a state where the upper and lower layers were joined, followed by heating and drying at 100 ° C. Then, Al (OH) ₃ (manufactured by Aldrich) and H ₃ PO ₄ (85%, manufactured by Junsei) were mixed so that the P / Al atomic ratio was 23, and then stirred while raising the temperature to 150 ° C OH) ₃ powder was dissolved in phosphoric acid to prepare a clear and viscous solution and mixed with a mixed solvent of water and isopropyl alcohol in a weight ratio of 3: 1, so that the weight of aluminum phosphate in the total aluminum phosphate solution A solution of 20% on basis was prepared. Finally, the wound ceramic filter was coated with the aluminum phosphate coating solution using a dipping coating method, dried at 110 ° C., and calcined at 1000 ° C. in an atmospheric condition to prepare a desired wound ceramic filter.

Example  2

A desired wound ceramic filter was manufactured in the same manner as in Example 1, except that 10 wt% of the organic fiber was added to the ceramic fiber.

Example  3

A desired wound ceramic filter was manufactured in the same manner as in Example 1, except that 15 wt% of the organic fiber was added to the ceramic fiber.

Example  4

A desired wound ceramic filter was manufactured in the same manner as in Example 1, except that 20 wt% of the organic fiber was added to the ceramic fiber.

Example  5

A desired wound ceramic filter was manufactured in the same manner as in Example 1, except that 25 wt% of the organic fiber was added to the ceramic fiber.

Example  6

A desired wound ceramic filter was manufactured in the same manner as in Example 2, except that a solution having a weight of 50% based on the solids content of aluminum phosphate in the total aluminum phosphate solution was used.

Example  7

A desired wound ceramic filter was manufactured in the same manner as in Example 3, except that a solution in which the aluminum phosphate weight was 50% based on the solids content in the total aluminum phosphate solution was used.

Example  8

A desired wound ceramic filter was manufactured in the same manner as in Example 4, except that a solution in which the aluminum phosphate weight was 50% based on the solids content in the total aluminum phosphate solution was used.

Example  9

A desired wound ceramic filter was manufactured in the same manner as in Example 5, except that a solution having a weight of 50% based on the solids content of aluminum phosphate in the total aluminum phosphate solution was used.

Comparative example  One

3 g of alumina-silica fiber having an average length of 300 μm was added to 2000 ml of water, and the mixture was vigorously stirred to disperse the fibers. Then, 5 wt% of coniferous pulp was added to the ceramic fiber as an organic fiber, and then the ceramic paper had flexibility. 10 wt% of the acrylic binder was added to the ceramic fiber, and 5 ml of an aqueous 1% aluminum sulfate solution of pH 3 was added to adjust the pH of the entire slurry composition to about 5.5. Next, the mixture was continuously stirred gently so that the solids in the slurry were evenly mixed, and then a ceramic paper having a diameter of 9.5 cm and a thickness of 500 μm was prepared using a papermaking machine, and then dried at 110 ° C. and heat-treated at 1000 ° C. under atmospheric conditions. To remove the organic binder and the organic fiber to prepare a porous ceramic paper.

Comparative example  2

To the silica-alumina synthetic sol having a solid content of 10% by weight, isopropyl alcohol as a penetrating solvent was mixed in an amount of 1/4 with respect to the weight ratio of the sol to prepare a coating solution, and then Example 1- (1 The same ceramic green paper as that used before the corrugated ceramic green paper was coated by impregnating the coating solution, dried at room temperature, heated to 1000 ° C., and calcined to prepare a porous ceramic paper.

Test Example  One

Measurement of strength

The ceramic green paper before the waveform used in Examples 1 to 9 was coated with the respective aluminum phosphate coating liquids used in Examples 1 to 9, and then calcined at 1000 ° C. to prepare porous ceramic paper specimens. For each of the porous ceramic papers prepared in Fig. 2, the strength was measured using a texture analyzer (manufactured by Stable micro system; Texture analyzer XT plus) at a rate of 1 mm / min and a three points bending test was performed. Through bending strength was measured, the results are shown in Table 1 below.

In the case of a conventional ceramic filter, the strength of the ceramic filter after firing tends to deteriorate as the amount of the organic fiber is increased, but as shown in Table 1, the ceramic filter according to the present invention has a predetermined level of the amount of the organic fiber. Until the usage increases, the strength also increases because the inorganic hollow fiber replaces the space occupied by the organic fiber.

Test Example  2

Scanning electron microscope SEM ) Picture

The porous ceramic sheet paper prepared in Example 1 was coated with the aluminum phosphate solution used in Example 1- (3), dried at room temperature, heated to 1000 ° C., and calcined to prepare a porous ceramic sheet paper. Afterwards, a SEM photograph thereof is taken and illustrated in FIG. 2. Referring to FIG. 2, it can be seen that aluminum phosphate hollow fibers generated through ceramicization of organic fibers are present in several places. In addition, the SEM photograph of the cross section of the aluminum phosphate hollow fiber is shown in FIG. Referring to Figure 3, there is a void in the interior of the aluminum phosphate hollow fiber formed in accordance with the present invention, it can be confirmed that the organic fiber is carbonized and the remaining spot, and in the case of Comparative Example 2 of the SEM analysis result of the linear ceramic Since only the fibers exist and the irregular inorganic materials formed as the sol particles are sintered between the spaces, the permeability decreases much.

Test Example  3

gas Transmittance  Measure

Porous ceramic paper specimens prepared by coating the ceramic green paper before waveform used in Example 9 according to the present invention with the aluminum phosphate coating solution used in Example 9 and then firing at 1000 ° C., Comparative Examples 1 and 2 For each of the porous ceramic paper prepared in, to check the gas permeability change before and after firing at 1000 ℃ gas flow in accordance with the air pressure was confirmed and the results are shown in FIG. Referring to Figure 4, 1 represents the permeability curve according to the air pressure of the green paper before firing, 2 represents the permeability of the specimen subjected to heat treatment at 1000 ℃ after coating with the aluminum phosphate solution used in Example 9, 3 is The transmittance of the test piece according to Comparative Example 1 is shown, and 4 represents the transmittance of the test piece prepared in Step 2 as compared. Referring to FIG. 4, in the case of 2 (Example 9), since aluminum phosphate hollow fiber remains after firing, it can be seen that it almost matches the gas permeability of the green paper, and both the pulp and the organic fiber are blown off without the inorganic binder treatment. In the case of (Comparative Example 1), since the permeability was rather increased after firing, it was confirmed that all organic fibers were blown away and uneven pores remained in place, and when heat-treated after coating using a conventional silica-alumina composite sol In Comparative Example 2, pores were blocked due to the silica-alumina synthesis sol, and it was confirmed that the gas permeability was significantly poor.

Test Example  4

Maximum pore size, Average flow pore size  And flow measurement

Among the specimens used in Test Example 3, the porous ceramics prepared by coating the ceramic green paper before use in Example 9 with the aluminum phosphate coating solution used in Example 9 and then baking at 1000 ° C. were prepared. The distribution of the average flow pore size and pore size of the ceramic paper was measured for the ceramic paper specimen and the porous ceramic paper specimen prepared by Comparative Example 2. The measurement was measured using a device called PMI's capillary flow porometer, and the measuring principle is as follows. When air is injected into a sample completely wetted with a test solution of a certain surface tension and reaches a certain pressure, a drop of test solution, which fills the largest hole in the pores, bursts out. This is called the maximum pore. As the air continues to be injected, all of the small pores of the solution burst into the droplets, and each pore size is estimated based on the largest pore. Check the permeation rate by blowing air under the same conditions to the dried sample from which the solution that filled the smallest pore was removed.Mean flow pore corresponding to the air pressure that is 1/2 of the gas permeation rate of the dried sample. flow pore). The permeability of the gas at the largest pore size (BPD) and mean flow pore diamater (MFP), and air pressure of 0.5 inch water pressure (0.018 psi) Table 2 shows. In the case of the porous ceramic paper prepared in Comparative Example 2, the average flow pore size was 32.6 µm, which is larger, whereas the large amount of particles blocked by the particles reduced the overall gas permeability to one-third than that of Example 9. You can check it.

As described above, the ceramic filter according to the present invention can obtain an excellent waveform state by using an organic fiber in a sufficient amount, and pores are formed due to the presence of inorganic hollow fiber having pores formed by carbonization of the organic fiber even after firing. It is uniform and has excellent gas permeability and at the same time has excellent mechanical strength. In addition, according to the method of manufacturing a ceramic filter according to the present invention, by forming an aluminum phosphate hollow fiber having a void formed by carbonization of an organic fiber in the filter, it is possible to manufacture a ceramic filter having uniformly maintained pores and excellent mechanical strength. have.

Claims (18)

And a porous ceramic paper including an inorganic fiber, wherein the inorganic fiber includes pores formed by carbonization of an organic component. 2. The ceramic filter of claim 1, wherein the inorganic fiber is an aluminum phosphate hollow fiber. The ceramic filter according to claim 1, wherein the organic component is an organic fiber. The ceramic filter according to claim 1, wherein the ceramic filter has a honeycomb structure in which ceramic corrugated paper and ceramic plate paper are bonded to each other. The ceramic filter according to claim 4, wherein the ceramic corrugated paper and the ceramic plate paper are made of the same material. The bending strength after firing of the ceramic paper is 1.0 MPa or more, and the gas permeability is 10 cc / sec / cm ^2. The ceramic filter characterized by the above. (a) preparing a ceramic green paper using a slurry composition of 0.1-10 mm long ceramic fibers, organic fibers and organic binders; (b) first drying the ceramic green paper; (c) fabricating a ceramic filter using the dried ceramic green paper; (d) coating the ceramic filter with an aluminum phosphate solution; And (e) preparing a porous ceramic filter comprising drying the ceramic filter coated with the aluminum phosphate solution and baking the same, thereby forming an aluminum phosphate hollow fiber having a void formed in the ceramic filter by carbonizing the organic fiber. Way. (a) preparing a ceramic green paper using a slurry composition of 0.1-10 mm long ceramic fibers, organic fibers and organic binders; (b) first drying the ceramic green paper; (c) coating the dried ceramic green paper with an aluminum phosphate solution; (d) carbonizing the organic fiber by drying and firing the ceramic green paper coated with the aluminum phosphate solution to form an aluminum phosphate hollow fiber in the ceramic paper in which voids are formed; And (e) manufacturing a ceramic filter using a ceramic paper comprising ceramic phosphate hollow fibers having the voids formed therein. The ceramic fiber according to claim 7 or 8, wherein the ceramic fiber is at least one selected from the group consisting of alumina, aluminosilicate, alumino borosilicate, mullite, and mixtures thereof, wherein the content of the ceramic fiber in the slurry composition is a solid content in the slurry composition. A method for producing a ceramic filter, characterized in that 50 to 80% by weight based on. The method according to claim 7 or 8, wherein the organic fiber is at least one selected from the group consisting of natural fibers, synthetic fibers and mixtures thereof, and the content of organic fibers in the slurry composition is 5 to 50% by weight of the ceramic fiber content. Method for producing a ceramic filter characterized in that. The method of claim 7 or 8, wherein the organic binder is methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, purified starch, dextrin, polyvinyl alcohol, polyvinyl butyral, polymethylmethacrylate, polyethylene glycol At least one selected from the group consisting of paraffins, wax emulsions, microcrystalline waxes, and mixtures thereof, wherein the content of the organic binder in the slurry composition is 1 to 20% by weight of the ceramic fiber content. The method of claim 7 or 8, wherein the slurry composition further comprises a pH adjusting agent. 13. The method of claim 12, wherein the pH adjusting agent is ammonium aluminum sulfate. 9. A method according to claim 7 or 8, wherein the aluminum phosphate solution is prepared by mixing aluminum hydroxide and phosphoric acid, and the P / Al atomic ratio in the solution is 3 to 50. The method of claim 7 or 8, wherein the aluminum phosphate solution further comprises selected from the group consisting of isopropyl alcohol and mixtures thereof as a penetration solvent. The method of claim 15, wherein the content of the penetrating solvent in the aluminum phosphate solution is 1 to 30 wt% based on the water content in the aluminum phosphate solution. The method of claim 7 or 8, wherein the weight of the aluminum phosphate in the aluminum phosphate solution is 1 to 80% based on the solids content. The method for producing a ceramic filter according to claim 7 or 8, wherein the firing temperature is 400 to 1100 ° C.

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