KR101237348B1 - Process for preparing aluminosilicate filter having excellent thermal shock resistance - Google Patents

Abstract

Disclosed is a method for producing a honeycomb type plugged aluminosilicate filter which can be produced economically, which is excellent in oxidation resistance and which can maintain filtration efficiency even for long-term use.

In the method for producing an aluminosilicate filter according to the present invention, a flat aluminosilicate fiber sheet and a corrugated aluminosilicate fiber sheet are alternately laminated, and only one end of the plurality of unit cells formed by the stacking is plugged with a ceramic sealant. As a result, the aluminosilicate filter can be economically produced without using the extrusion method, and the aluminosilicate filter prepared by the above method has an excellent porosity than the filter by the extrusion method and can maintain the filtration efficiency even when used for a long time. In addition, high temperature oxidation resistance can be improved by forming an oxidation resistant film on the aluminosilicate filter.

Aluminosilicate Filter, DPL

Description

 Process for preparing aluminosilicate filter having excellent thermal shock resistance

1 is a step-by-step diagram illustrating a method of manufacturing the plugged aluminosilicate filter of the present invention.

2 is a schematic diagram of an aluminosilicate filter made by a method according to one embodiment of the invention.

DESCRIPTION OF THE REFERENCE NUMERALS

1, 1 ': flat aluminosilicate fiber sheet

2, 2 ': ceramic sealant

3: corrugated aluminosilicate fiber sheet

The present invention relates to a method for producing particulate aluminosilicate (Al ₂ O ₃ -SiO ₂ ) filter for removing dust generated in diesel vehicles and other industrial sites, and more particularly economically. The present invention relates to a method for preparing a plugged aluminosilicate filter which can maintain filtration efficiency even after long-term use and excellent in high temperature oxidation resistance, and to an aluminosilicate filter prepared therefrom.

As the industry develops, the harmful substances such as dust, soot, waste gas, smoke, and volatile organic chemicals (VOC's) generated in each industrial process are increasing. Therefore, in order to prevent the emission of such pollutants, some polymer filters are used, but polymer filters have weak problems in heat resistance, chemical resistance, abrasion resistance, and flame resistance.

In other words, polyester shrinks at 150 ° C, and PTFE (Teflon), which has excellent heat resistance, has only heat resistance up to 250 ° C. The atmosphere of the process using an industrial filter is dust, various waste gases, and moisture. This is a harsh environment that occurs at the same time. Most polymer nonwoven filters, such as polyester, polypropylene, acrylic, polyamide, polyimide, and glass fiber, shake off the dust on the surface of the filter by jet pulses. As the dust falls, the surface abrasion of the filter caused by the dust is worse than expected, which causes the filter to break and shorten the life cycle of the filter.

In addition, if a spark is generated during the combustion process of each industry and is attached to the filter, the flame attached to the filter may lead to a fire or a hole in the filter, and in the case of waste incinerators, boilers, coal-fired power plants, and coal gasification combined cycle, There is a problem that the risk of exposure to the atmosphere, contrary to tightened environmental regulations.

Therefore, the development of a ceramic filter has been made in order to solve this problem, in particular, an extrusion type silicon carbide (SiC) filter produced by extruding, drying and heat-treating a composition containing silicon carbide powder is widely used.

In the case of the extruded silicon carbide filter, the silicon carbide has excellent hardness and thermal conductivity, but the manufactured extruded filter is relatively heavy and has a problem of pressure drop because the porosity is only 40%. It is very likely to occur.

On the other hand, diesel engines are low in fuel consumption and have excellent reliability, and thus are widely used in automobiles, ships, general industries, etc., and have high demands for power output and high load operation. However, diesel cars are recognized as the leading cause of air pollution, accounting for 40% of total air pollution. Air pollution by these diesel vehicles is mainly caused by nitrogen oxides (NOx) and particulate matter (PM).

In order to prevent air pollution caused by diesel cars, countries are tightening exhaust gas regulations. The main targets of these regulations are nitrogen oxides and particulate matter. There is a method of improving the combustion performance of an engine for reducing the concentration of nitrogen oxides by exhaust gas recirculation and reducing particulate matter.

In other words, concrete countermeasures for diesel vehicle exhaust regulation are divided into engine improvement and aftertreatment technology. First, engine improvement technologies include fuel chamber improvement, intake system improvement (turbo charger and intercooler), and fuel injection system improvement (electronic control). High pressure fuel injection device), exhaust gas recirculation device and the like are being applied or under development.

In addition, the post-treatment technology includes an oxidation catalyst for purifying high-boiling hydrocarbons in particulate matter, a denitrification oxide catalyst for decomposing or reducing nitrogen oxides in an excess oxygen atmosphere, and a diesel particulate filter for filtering particulate matter. There is a system (Diesel Particulate Filter: DPF).

Among the post-treatment techniques, the particulate matter removal filter system has the advantage of reducing the emissions by reliably capturing soot, but the back pressure of the exhaust gas increases due to the increase of particulate matter trapped in the DPF over time, thereby burdening the engine. There is a growing problem.

For this reason, the reduction of the back pressure of the DPF itself and the regeneration method of burning and removing the collected particulate matter become an important factor in determining the performance of the DPF.

As the material of the DPF, aliminosilicate and silicon carbide (SiC) have attracted attention due to problems such as thermal expansion and durability during regeneration by the combustion of the collected particulate matter.

The DPF produces a honeycomb structure having a porous partition wall arranged to form a plurality of cells extending axially from one end face to the other end face in an extrusion manner, and at least a portion of the cell It can be manufactured in the form of a plugged honeycomb structure including a plugging process in which the plug is plugged on the surface. In this case, the manufactured filter is heavy, and since the porosity is only up to 40%, a pressure drop occurs and thus the filtration efficiency. This falling problem may occur. In addition, the extrusion method requires a costly extrusion molding apparatus and requires high temperature firing, so there is a problem in that energy is consumed, and it is difficult to manufacture a large volume DPF.

In order to solve this problem, aluminosilicate sheets prepared using aluminosilicate fibers are corrugated with an embossing roller, and then the honeycomb structure is formed by gluing and laminating the corrugated sheet and the flat sheet and then plugging the DPF. In this case, there is a problem in that the strength of the filter produced is low because the bonding strength between the aluminosilicate fibers is weak.

Accordingly, there is still a need for a method that can produce plugged aluminosilicate filters that are superior in strength and excellent in oxidation resistance using relatively aluminosilicate fibers.

Therefore, the first technical problem to be achieved by the present invention is to provide a method for producing a plugged aluminosilicate filter which can be manufactured economically, the filtration efficiency can be maintained for a long time, and excellent in strength and high temperature oxidation resistance.

The second technical problem to be achieved by the present invention is to provide a plugged aluminosilicate filter manufactured using the above production method.

In the present invention to achieve the first technical problem

(a) applying a ceramic sealant over one end of the flat aluminosilicate fiber sheet;

(b) laminating the corrugated aluminosilicate fiber sheet on the flat aluminosilicate fiber sheet;

(c) applying a ceramic sealant on top of the corrugated aluminosilicate fiber sheet at an end opposite the end to which the ceramic sealant is applied;

(d) laminating a flat aluminosilicate fiber sheet on the corrugated aluminosilicate fiber sheet; And

(e) repeating steps (b) to (d) several times to form a laminate in which the flat aluminosilicate fiber sheet and the corrugated aluminosilicate fiber sheet are alternately laminated; And

(f) impregnating the laminate with a slurry comprising silicon powder, a phenol resin and an alcohol, followed by heat treatment in an inert atmosphere, to provide a method for producing a plugged aluminosilicate filter.

According to one embodiment of the present invention, the corrugated aluminosilicate fiber sheet is a hot waveform by impregnating a raw aluminosilicate fiber sheet or a flat aluminosilicate fiber sheet in a slurry in which silicon powder is dispersed in a thermoplastic resin solution. And then cooled.

According to another embodiment of the present invention, a ceramic adhesive may be applied together with the ceramic sealant.

According to another embodiment of the present invention, after the heat treatment step (f), (g) the resultant may be further included after the impregnation in the slurry containing alumina sol and heat treatment again .

The present invention provides a plugged aluminosilicate filter manufactured by the above method to achieve the second technical problem.

The production method according to the present invention can produce a plugged aluminosilicate filter with excellent strength, and unlike the extruded aluminosilicate filter, the porosity is high, and thus the filtration efficiency is excellent.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The method for producing a plugged aluminosilicate filter according to the present invention comprises the steps of: (a) applying a ceramic sealant over one end of a flat aluminosilicate fiber sheet;

(b) laminating the corrugated aluminosilicate fiber sheet on the flat aluminosilicate fiber sheet;

(c) applying a ceramic sealant on top of the corrugated aluminosilicate fiber sheet at an end opposite the end to which the ceramic sealant is applied;

(d) laminating a flat aluminosilicate fiber sheet on the corrugated aluminosilicate fiber sheet; And

(e) repeating steps (b) to (d) several times to form a laminate in which the flat aluminosilicate fiber sheet and the corrugated aluminosilicate fiber sheet are alternately laminated; And

(f) impregnating the laminate with a slurry comprising silicon powder, phenol resin and alcohol, followed by heat treatment in an inert atmosphere.

Hereinafter, a manufacturing method according to the present invention will be described step by step with reference to FIG.

(a) step

As shown in Fig. 1 (a), the ceramic sealant 2 is coated on one end of the flat aluminosilicate fiber sheet 1.

The flat aluminosilicate fiber sheet 1 used in the process according to the invention can be produced by leveling a raw aluminosilicate fiber sheet.

The aluminosilicate fiber sheet is made of aluminosilicate fibers, and any porous structure having pores supporting the composition can be used, and in particular, it is more preferable to use paper, nonwoven fabric, woven fabric, and the like. .

In the case of the paper, the honeycomb structure formed by laminating it has good heat resistance and corrosion resistance, and is lighter than that formed by extrusion molding, so that the pressure loss of the combustion exhaust gas is reduced, and thus, it is attracting attention as a gas phase reaction catalyst and heat exchange element.

In other words, since paper is a sheet of paper, aluminosilicate fibers are easily formed, embossed, or bonded by a conventional paper processing method, and thus, development of a structure that utilizes heat resistance, electrical properties, porosity, and adsorption functions has been actively conducted. . In addition, the honeycomb structure manufactured through corrugate processing to corrugate is particularly preferable in the present invention because it can be used as a heat exchanger, a catalyst carrier, a dehumidifier, a filter for an environmental purifier, a heat insulating material, and the like.

The nonwoven fabric is formed by combining short fibers with an adhesive on the basis of a web or sheet-like fiber aggregate, bonding the fibers using thermoplastic fibers, or entangles the fibers by needle punching or sewing. .

The woven fabric is manufactured by spinning, weaving, cotton, or the like, and is preferably woven loosely for supporting the slurry, and includes sufficient pores for supporting the slurry in the woven fabric.

The ceramic sealant 2 may be a paste including 20 to 40 parts by weight of the binder solution based on 100 parts by weight of the silicon carbide-silicon mixed powder. In this case, the silicon carbide-silicon mixed powder may be prepared by mixing 50 to 100 parts by weight of silicon powder with respect to 100 parts by weight of silicon carbide powder, and the binder solution may be prepared by mixing and dissolving 5 to 30 parts by weight of the binder with respect to 100 parts by weight of the solvent. have.

If the binder is less than 5 parts by weight, the viscosity of the binder solution is too low, so that the molding strength after drying and heat treatment of the sealing material is not sufficient. If the binder is more than 30 parts by weight, the viscosity of the binder solution is too high, It is also undesirable because dispersion and sealant paste production are difficult.

The binder solution included in the sealant serves as a medium for dispersing the silicon carbide or silicon well so as not to precipitate or phase-separate, and then serves as an adhesive with the sheet when applied to the sheet for the production of honeycomb filters. To provide a bond.

Examples of the binder used in the binder solution include an organic binder or an inorganic binder. The organic binder is, for example, polyvinyl alcohol (PVA, Polyvinyl alcohol), polyvinyl acetate (PVAc, Polyvinyl acetate), starch (Corn Starch), methyl cellulose (MC, Methyl Cellulose), carboxymethyl cellulose (CMC, Carboxymethyl Cellulose), hydroxyethyl cellulose (HEC, Hydroxyethyl Cellulose), poly acrylate, polyacrylamide, or a mixture thereof. Examples of the inorganic binder may include silica sol, alumina sol, silane, or a mixture thereof. have. Such a binder forms the binder solution by mixing with a solvent such as water, methanol, ethanol or a mixture thereof.

The ceramic sealant may further include carbon, and the content thereof may be 0.1 to 5 parts by weight based on 100 parts by weight of the silicon carbide-silicon mixed powder.

On the other hand, silicon or silicon carbide contained in the ceramic sealant may be used in the form of a powder having a particle size of about 0.1 to 50㎛, when the particle size is less than 0.1㎛ is preferable because there is a problem such as an increase in the manufacturing cost but good manufacturing cost In addition, when it exceeds 50 micrometers, there exists a problem, such as a fall of a bonding force and a fall of a compactness, and is unpreferable.

The sealant may further include various additives such as a curing accelerator, a pigment, an emulsifier, a functional filler, a dispersant, an antifoaming agent, a stabilizer, a leveling agent, a tackifier, a catalyst, or a mixture thereof, together with the components, which are silicon carbide. It may be added in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the silicon mixed powder.

A ceramic adhesive may be applied together with the ceramic sealant.

The ceramic adhesive may include 100 to 300 parts by weight of resin based on 100 parts by weight of the metal powder.

The resin may be used in an amount of 100 to 300 parts by weight based on 100 parts by weight of the metal powder, and if the content is less than 100 parts by weight, it is not preferable because the viscosity is very high and disadvantageous to the process. It is not preferable because the amount of metal carbide (ex. Silicon carbide) binder produced by the reaction of the metal powder and the resin carbide is relatively reduced, and the unreacted resin carbide is largely left, resulting in a weakening of the high temperature adhesive strength.

They can bond the ceramic fiber sheets to each other to produce a filter for various uses, in particular, the metal carbide produced by the reaction of the metal powder and the carbide of the resin in the adhesive composition in a high-temperature reducing atmosphere acts as an adhesive between the ceramic fiber sheets, It will improve the mechanical strength and heat transfer characteristics of the ceramic fiber sheet while maintaining a stable adhesion.

The resin used in the ceramic adhesive has adhesiveness or tackiness, which is used for initial adhesion between sheets, and when placed under a high temperature reducing atmosphere, it acts as a carbon source and reacts with metal powder in the composition to produce metal carbide between ceramic fiber sheets. It will act as an adhesive.

A thermosetting resin is mentioned as said resin, An epoxy resin, a melamine resin, an alkyd resin, a urea resin, a phenol resin, an unsaturated polyester resin, a polyurethane resin etc. are mentioned. Preferably, a phenol resin can be used.

As the phenol resin used in the present invention, any one can be used as long as it is a phenol resin having at least two or more phenolic hydroxyl groups in one molecule. Specifically, novolak-type phenol resins, resol-type phenol resins, phenol aralkyl resins, and tri- Phenolic resins, such as a phenol alkane type resin and its polymer, a naphthalene ring containing phenol resin, etc. are illustrated. In particular, when the naphthalene ring-containing phenol resin is used in combination, a thermosetting resin composition is obtained because of low hygroscopicity and further excellent adhesion. Moreover, you may use together with an amine hardening | curing agent and an acid anhydride type hardening | curing agent.

As the epoxy resin used in the present invention, a resin having a structure having two or more oxirane rings in a molecule, for example, glycidyl ether, glycidyl ester, glycidyl amine, linear aliphatic epoxy Resins such as epoxite and cycloaliphatic epoxides can be used alone or in combination. Specifically, bifunctional, such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin and naphthalene type epoxy resin, epoxy resin, triglycidyl isocyanurate type epoxy resin, Triglycidyl-p-aminophenol type epoxy resin, tetraglycidyl diaminodiphenyl methane type epoxy resin, tetraglycidyl m-xylenediamine type epoxy resin and tetraglycidyl-1,3-bisaminomethyl Multifunctional glycidyl amine type epoxy resins such as cyclohexane type epoxy resins, multifunctional glycidyl ether type such as tetraphenyl glycidyl ether ethane type epoxy resins and triphenyl glycidyl ether methane type epoxy resins Multifunctional resol type epoxy resin such as epoxy resin, phenol type epoxy resin, alkylphenol type epoxy resin, phenol type epoxy resin and cresol type epoxy It can be given to a group of jideung novolak type epoxy resin as an example. Among these, it is preferable that bisphenol type epoxy resin is used especially from a low cost viewpoint, and a polyfunctional group epoxy resin is used from an insulation and heat resistance viewpoint.

As such a metal powder, a powder having various particle diameters may be used, and the powder may have the same particle diameter, or may be used by mixing powder components having different particle diameters. The particle diameter of the said metal powder becomes like this. Preferably it is 0.1-50 micrometers. If the particle diameter of the metal powder is less than 0.1㎛, there is a problem of product cost increase, and if it exceeds 50㎛, the chemical resistance degradation caused by the metal powder is not sufficiently converted to metal carbide, but remains as a metal component itself, It is not preferable because there is a problem such as a decrease in strength.

The metal powder used in the ceramic adhesive reacts with the resin to form metal carbide when placed under a high temperature reducing atmosphere. For example, silicon (Si), alumina, aluminosilicate (Al ₂ O ₃ -SiO ₂ ) , Silica (SiO ₂ ) or mixtures thereof may be used, and silicon may be preferably used.

As such a metal powder, the component which has various particle diameters can be used, a predetermined component may have the same particle diameter, and the same component which has a different particle diameter can also be mixed and used. The particle diameter of the said metal powder becomes like this. Preferably it is 0.1-50 micrometers. If the particle diameter of the metal powder is less than 0.1㎛, there is a problem of product cost increase, and if it exceeds 50㎛, the chemical resistance degradation caused by the metal powder is not sufficiently converted to metal carbide, but remains as a metal component itself, It is not preferable because there is a problem such as a decrease in strength.

In addition to the resin, various additives such as a curing accelerator, a pigment, an emulsifier, a functional filler, a dispersant, an antifoaming agent, a stabilizer, a leveling agent, a tackifier, a catalyst, and the like may be used in the ceramic adhesive. It can be used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of powder. The ceramic adhesive serves to promote adhesion of the flat carbon fiber sheet layer and the corrugated carbon fiber sheet layer to be laminated thereon.

(b) step

As shown in Fig. 1 (b), the corrugated aluminosilicate fiber sheet 3 is laminated on the flat aluminosilicate fiber sheet 2.

The corrugated aluminosilicate fiber sheet is prepared by impregnating, drying and hot corrugating a raw aluminosilicate fiber sheet or a flat aluminosilicate fiber sheet into a slurry comprising thermoplastic resin, filler and solvent, and then cooling. The impregnation slurry may include 0 to 200 parts by weight of the filler, and 500 to 1800 parts by weight of the solvent, based on 100 parts by weight of the thermoplastic resin.

In addition, the impregnation slurry may be used as necessary, various additives such as a reaction initiator, a curing accelerator, a curing delay agent, and the content thereof may be used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic resin.

The thermoplastic resin, which is the subject of the slurry for impregnation, may be used without limitation as long as it is a polymer material softened at high temperature and hardened upon cooling. In the present invention, it is preferable to use polyvinyl alcohol, polyvinylacetate, or a mixture thereof. desirable.

Silicon may be used as the filler, and the reason for dispersing the silicon in the thermoplastic resin and impregnating the same as the filler is that in order to convert the carbon fiber to the silicon carbide component, silicon powder is supplied in the maximum number of steps as much as possible. Because it can increase. In fact, in the silicon slurry impregnation process, which is a part of the process of manufacturing the honeycomb filter, it is desirable to add an excessive amount of silicon in the silicon slurry in order to supply the silicon to the maximum conversion, so that the surface of the aluminosilicate fiber sheet This is because aggregation occurs and uniform dispersion between the aluminosilicate fibers becomes difficult. Therefore, when silicon is pre-injected into the slurry for impregnation, silicon is infiltrated in advance between the aluminosilicate fibers, thereby obtaining more homogeneous silicon carbide (SiC). The filler is preferably used in an amount of 0 to 200 parts by weight based on 100 parts by weight of the thermoplastic resin. When the content is more than 200 parts by weight, the elastic force of the impregnated sheet is reduced during the corrugation process due to the aggregation of silicon powder. There is a problem that can be broken and there is no big problem even if the silicon powder is not added, but it is preferable to add even a small amount in terms of increasing the silicon carbide conversion rate by adding a little silicon powder.

As the filler, a component having various particle diameters may be used, and certain components may have the same particle diameter, or a mixture of the same components having different particle diameters may be used. The particle size of such a filler is preferably 0.1 to 100 μm, and when the particle size of the filler is less than 0.1 μm, there is a problem such as an increase in product cost. When the particle size exceeds 100 μm, the filler is a pore of the aluminosilicate fiber sheet. There is a problem such that the impregnation is not uniformly impregnated, which is not preferable.

As a solvent used in the impregnation slurry for the corrugating method according to the present invention, water, alcohols, ethers or a mixture thereof may be used, and as the alcohols, for example, methanol, ethanol, isopropyl alcohol. , Butyl alcohol, octyl alcohol, benzyl alcohol, cyclohexanol, ethylene glycol, glinerol, diethylene glycol, and the like can be used, the ethers can be used cellosolve, butyl cellosolve and the like.

The solvent is preferably contained in 100 to 2000 parts by weight based on 100 parts by weight of the thermoplastic resin.

When the content of the solvent is less than 100 parts by weight, the viscosity of the thermoplastic resin solution becomes too high, and uniform mixing and dispersion of the silicon powder in the thermoplastic resin solution is not possible, so that uniform impregnation of the aluminosilicate fiber sheet is impossible. In addition, since the thermoplastic resin blocks pores in the aluminosilicate fiber sheet, there is a problem that no uniform impregnation of the silicon slurry occurs during the subsequent silicon slurry impregnation process. In addition, when it exceeds 2000 parts by weight, the viscosity of the thermoplastic resin solution is too low, that is, the content of the thermoplastic resin is too low, it is not preferable to exhibit the shape holding force necessary for maintaining the waveform shape during hot waveforms.

The corrugating method is, for example, after impregnating the raw aluminosilicate fiber sheet or the flat aluminosilicate fiber sheet into the slurry and passing through the interlocking gear of the corrugating apparatus heated to 150 ° C. to 200 ° C. and cooling in air. When the thermoplastic resin is softened at high temperature, the aluminosilicate fiber sheet is formed into a gear-shaped corrugated form to obtain a corrugated aluminosilicate fiber sheet that maintains its shape when cooled.

The impregnating slurry not only helps to corrugate the aluminosilicate fiber sheet, but the thermoplastic resin improves the inter-fiber adhesion of the aluminosilicate fiber sheet, and the silicon powder serves to change the carbon component into the silicon carbide component. .

Through the lamination, as shown in FIG. 1B, a plurality of unit cells in which a ceramic sealant is positioned at one end is formed.

(c) step

As shown in FIG. 1 (c), the ceramic sealant 2 ′ is applied to the top of the corrugated aluminosilicate fiber sheet 3 at the opposite end to the end where the ceramic sealant 2 is applied.

The ceramic sealant 2 ′ may be the same as the ceramic sealant 2 of step (a), and may be applied together with a ceramic adhesive (not shown).

(d) step

Then, as shown in FIG. 1 (d), the flat aluminosilicate fiber sheet 1 ′ is laminated again on the corrugated aluminosilicate fiber sheet 3.

Likewise, a plurality of unit cells in which the ceramic sealant is positioned at the other end is formed through the lamination.

(e)

The process is repeated several times to form a laminate in which the flat aluminosilicate fiber sheet and the corrugated aluminosilicate fiber sheet are alternately stacked as shown in FIG.

(f)

The laminate is then immersed in a slurry comprising silicon powder, phenol resin and alcohol and then heat treated under reducing atmosphere to obtain a plugged aluminosilicate filter.

The aluminosilicate fiber sheet laminate has good heat resistance and corrosion resistance, and has a low pressure drop due to light weight and high porosity than that formed by extrusion molding, and a three-dimensional filtering method of deep bed filtration. Since it is filtered by the method, the filtration efficiency is also excellent.

The impregnation may use a method of applying the slurry to the laminate, dipping the laminate into the slurry, or spraying (spraying) the slurry onto the laminate, and in particular, the slurry may It is sufficient to include enough, and repeat the process of dipping and squeezing the laminate to the slurry two or three times to be seated, or the process of applying or spraying the slurry to the laminate two or three times to repeat the slurry is laminated It is better to make sure that it is supported enough.

The silicon powder in the slurry used for the impregnation may have various particle diameters, preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 20 μm, and even more preferably 1 μm to 10 μm. When the particle diameter of the silicon powder is in the above range, there is an effect that can improve the pore formation and mechanical strength of the filter. In addition, the slurry impregnation is excellent, there is an effect that can be uniformly slurry-impregnated ceramic fiber filter.

That is, when the particle size of the metal silicon powder is less than 0.1 μm, it is difficult to apply mass production because it is quite expensive, and when it exceeds 100 μm, it is not impregnated into the inside of the carbon fiber filter and is present on the surface as a cake to dry. In addition to the problem of peeling (peeling), it is not preferable because there is a problem in producing the desired silicon carbide fiber filter by forming the silicon carbide fibers unevenly only in the portion where the metal silicon powder is present in the filter molded body.

The slurry for impregnating the laminate may include 20 to 60 parts by weight of phenolic resin, and 50 to 200 parts by weight of alcohol, based on 100 parts by weight of silicon powder. If the content of the phenol resin is less than 20 parts by weight, it is not preferable because the amount of carbides that bind the carbon fibers is not sufficient. If it exceeds 60 parts by weight, the amount of carbides that binds the carbon fibers is excessively high and carbonized. It is not converted to silicon and remains as carbides, oxidized and blown away at a high temperature, resulting in a decrease in strength, which is undesirable.

As the alcohol, for example, one selected from methanol, ethanol, isopropyl alcohol, butyl alcohol, octyl alcohol, benzyl alcohol, cyclohexanol, ethylene glycol, glycerol and diethylene glycol can be used.

When the alcohol is less than 50 parts by weight, the fluidity of the slurry cannot be sufficiently supplied, so that the carbon fiber sheet honeycomb cannot be sufficiently impregnated, and when it is more than 200 parts by weight, the content of the metal silicon and phenol resin in the slurry is It is not preferred because it is relatively low and there is not enough supply of silicon and phenol.

The heat treatment is performed under an inert atmosphere, ie a vacuum atmosphere or an inert gas of argon or nitrogen. Looking at the heat treatment process in detail, first, the organic material in the aluminosilicate fiber sheet honeycomb impregnated with the silicon slurry is degreased, and is composed of a carbonization process for converting the organic material into carbides and a high temperature baking process in an inert atmosphere. First, the degreasing step is to gradually increase the temperature and maintain in a vacuum or inert atmosphere from 800 ℃ to 1000 ℃ at room temperature, 1 to 3 ℃ at room temperature to prevent deformation and breakage of the filter that may occur during the temperature increase during the heat treatment The temperature is raised at a rate of / min and kept sufficiently for 2 hours or more to completely convert the organics into carbides.

The degreasing molded body is subjected to heat treatment in an inert atmosphere in a high temperature firing furnace. In this case, when the temperature increase rate is raised at a rate of 1 ° C. to 3 ° C./min, the holding temperature is 1410 ° C. or more, which is the melting point of the metal silicon, More preferably, it is sufficiently maintained at 1600 ° C. or higher, and the cooling is natural cooling to minimize the amount of thermal shock applied to the filter. The holding time may vary depending on the size of the sample, and is generally maintained for more than 5 hours to completely convert the carbon to silicon carbide.

If the final temperature of the heat treatment is less than 1410 ℃ is not preferable because there is a problem that the silicon does not melt and is not converted to silicon carbide.

As the heat treatment proceeds, a silicon carbide layer begins to form from the surface of the aluminosilicate fiber. At this time, the remaining silicon forms the outermost layer of the filter. If silicon does not remain, the outermost layer forms SiO ₂ through heat treatment under an oxidizing atmosphere.

The slurry comprising silicon powder, phenol resin and alcohol used for impregnation during the heat treatment is polyvinyl alcohol and silicon powder used in the manufacture of corrugated aluminosilicate fiber sheets, silicon powder of ceramic adhesive and silicon carbide together with phenol resin. Forming a bond between the aluminosilicate fiber sheets that ultimately constitutes the filter, and carbides of the ceramic sealant are β-siliconized to plug only one end of the plurality of unit cells.

As the heat treatment proceeds, the slurry used for impregnation, the ceramic adhesive and the slurry used for corrugation react with the aluminosilicate fibers to form a SiC-Al ₂ O ₃ -SiO ₂ interfacial phase to form aluminosilicate fibers. Make the bond stronger.

After the step (f), an oxidation resistant film may be formed on the surface of the composite by performing an additional heat treatment to be described below under an oxidation atmosphere.

(g) step

After the result of the step (f) is impregnated into a slurry containing alumina sol (AlOOH sol), it can be heat-treated under an oxidizing atmosphere.

At this time, the silicon carbide on the surface of the aluminosilicate fiber is converted to silicon dioxide by the slurry containing the alumina sol (AlOOH sol) to form an aluminum oxide film thereon.

Looking specifically at the heat treatment process for forming the oxidation resistant film, it is preferable to increase the temperature from room temperature to 1000 ℃ at a rate of 1 to 10 ℃ / min, maintained for 0.5 to 5 hours to complete the heat treatment.

The reason for forming such an oxidation resistant film is to prevent the filter from being oxidized upon continuous exposure to hot air.

At this time, even if there is only SiO ₂ layer by oxidation of some silicon carbide there is an advantage that the oxidation resistance is improved, but more preferably, in order to give a crack prevention property against degradation to increase the life of the filter, on the SiO ₂ layer It is more preferable to form an Al ₂ O ₃ layer.

At this time, the slurry containing alumina sol is preferably 10 to 30 parts by weight of AlOOH nanopowder with respect to 100 parts by weight of the slurry, if the content is less than 10 parts by weight there is a problem that a sufficient amount of Al ₂ O ₃ film is not formed However, when the content exceeds 30 parts by weight, the internal coating of the porous material is problematic due to the high viscosity, which is not preferable.

The silicon carbide composite fiber filter manufactured by the method according to the present invention can be cut and used to the required shape and size as schematically shown in FIG.

The plugged aluminosilicate fiber filter produced by the method according to the present invention has a cell density of 50 cpi to 300 cpi and a porosity of 50 to 80% of the unit cell, which is excellent in filtration efficiency and does not sharply drop even after long-term use.

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

Example 1

After preparing several sheets of aluminosilicate fiber sheets having a width of 300 mm, a length of 400 mm, and a thickness of 0.4 mm, 1000 parts by weight of water was uniformly mixed with respect to 100 parts by weight of polyvinyl alcohol to prepare a PVA solution. The solution was uniformly impregnated with a carbon fiber sheet and dried, and planarized using a thermopressor.

The impregnated and leveled aluminosilicate fiber sheet was hot corrugated at 80 ° C. to 150 ° C. and then cooled to prepare a corrugated aluminosilicate fiber sheet.

On one end of the leveled aluminosilicate fiber sheet, a ceramic adhesive comprising 100 parts by weight of phenol resin resin and 100 parts by weight of silicon carbide-silicon mixed powder (weight ratio is 2: 1) on 100 parts by weight of silicon powder 30 wt parts of a 5 wt% polyvinyl alcohol aqueous solution was mixed, and then a ceramic sealing material prepared by mixing / kneading was uniformly applied using a stirrer, and then the corrugated aluminosilicate fiber sheet was laminated. The same ceramic adhesive and ceramic sealant as described above were applied onto the corrugated aluminosilicate fiber sheet at the end opposite the end to which the ceramic sealant was applied. A flat aluminosilicate fiber sheet was laminated on the corrugated aluminosilicate fiber sheet. The above procedure was repeated to obtain a laminate.

The laminate was impregnated with a silicon powder slurry I containing 40 parts by weight of phenol resin and 100 parts by weight of ethanol (after heat treatment, a composition in which unreacted metal silicon does not remain) with respect to 100 parts by weight of silicon powder, and then the laminate Hot air was dried at a temperature of 80 ℃ ~ 90 ℃. The dried laminate was subjected to a degreasing process by heat treatment at 800 ° C. for 2 hours in a non-oxidizing atmosphere, and then heat-treated at 1600 ° C. for 2 hours in a non-oxidizing atmosphere. Heat treatment was performed at a rate of 1 ℃ / min from room temperature to 800 ℃ to prevent deformation and damage of the filter that can occur during the temperature rise, and after raising the temperature at a rate of 5 ℃ / min from 800 ℃ to 1600 ℃, the final The heat treatment was completed by maintaining at a temperature of 1600 ℃ for 2 hours to prepare a cube honeycomb aluminosilicate fiber filter of the width / length / height 200mm / 200mm / 200mm size.

The plugged aluminosilicate fiber filter was then impregnated with AlOOH sol slurry (product name: NYACOL AL20, purchased from NYACOL NANO TECHNOLOGIES, Inc.) and then placed in an electric furnace to 1000 ° C. at room temperature at a rate of 5 ° C./min in air. After raising the temperature, the mixture was maintained for 2 hours to form an oxidation resistant film Al ₂ O ₃ . Then, the aluminosilicate fiber laminated molded body was processed, thereby producing a filter in a desired shape such as round or elliptical.

Comparative Example 1

In the same manner as in Example 1, in the case of the silicon powder slurry impregnated in the laminated aluminosilicate fiber sheet honeycomb block, a slurry in which 80 parts by weight of phenol resin and 200 parts by weight of ethanol was uniformly mixed with respect to 100 parts by weight of silicon powder Impregnated.

Test Example: Measurement of Physical Properties

The physical properties of the aluminosilicate filters of Example 1 and Comparative Example 1 prepared above were evaluated using the following method.

1) Three-point bending strength test: Five sheets of carbon fiber sheets (50mm / 20mm / 0.4t) were laminated, impregnated, and heat-treated according to the Examples and Comparative Examples to prepare a test bar having a thickness of 2.0 mm.

2) SiC property evaluation: A portion of the filter prepared in each Example and Comparative Example was removed and ground to a mortar to prepare a powder, and then compared the pattern through XRD.

3) Porosity: Porosity was measured using a mercury porosimeter.

4) Microstructure: The microstructure of the fiber was observed using SEM.

5) Oxidation Resistance Evaluation: After each sample was heat-treated in an oxidation atmosphere at 1400 ° C for a long time, the XRD evaluation was performed to compare the patterns.

It can be seen that the plugged aluminosilicate filter according to the present invention has excellent porosity, excellent oxidation resistance, and can maintain long-term filtration efficiency.

The method for producing a plugged aluminosilicate filter according to the present invention may provide a plugged aluminosilicate filter having superior porosity and excellent oxidation resistance than the extrusion method.

Claims (13)

(a) applying a ceramic sealant over one end of the flat aluminosilicate fiber sheet; (b) laminating the corrugated aluminosilicate fiber sheet on the flat aluminosilicate fiber sheet; (c) applying a ceramic sealant on top of the corrugated aluminosilicate fiber sheet at an end opposite the end to which the ceramic sealant is applied; (d) laminating a flat aluminosilicate fiber sheet on the corrugated aluminosilicate fiber sheet; (e) repeating steps (b) to (d) several times to form a laminate in which the flat aluminosilicate fiber sheet and the corrugated aluminosilicate fiber sheet are alternately laminated; And (f) impregnating the laminate with a slurry comprising silicon powder, a phenol resin and an alcohol, followed by heat treatment in an inert atmosphere, The ceramic sealing material is a paste containing a silicon powder, silicon carbide powder and an organic binder solution, characterized in that the manufacturing method of the aluminosilicate filter. The corrugated aluminosilicate fiber sheet is hot corrugated by impregnating a raw aluminosilicate fiber sheet or a flat aluminosilicate fiber sheet into a slurry comprising thermoplastic resin, filler and solvent. It is produced by negative cooling. The method of claim 1 wherein the flat aluminosilicate fiber sheet is produced by leveling an unprocessed aluminosilicate fiber sheet. The method of claim 2 wherein the thermoplastic resin is any one selected from the group consisting of polyvinyl alcohol (PVA), polyvinylacetate, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose. The method of claim 2 wherein the filler is silicon. delete The method of claim 1 wherein a ceramic adhesive is applied together with the ceramic sealant. 8. The method of claim 7, wherein said ceramic adhesive is a slurry comprising silicon powder and a phenolic resin. The method of claim 1 wherein the heat treatment under inert atmosphere is performed at a temperature of 1410 ° C. to 1700 ° C. under a vacuum, argon or nitrogen atmosphere. The method of claim 1, further comprising (g-1) heat treating the resultant in an oxidizing atmosphere after the step (f). The method of claim 10, further comprising (h) after the step (g-1), the resultant is impregnated into a slurry containing an alumina sol and then heat-treated again in an oxidizing atmosphere. The method of claim 1, further comprising the step of (g-2) after the step (f), the resultant is impregnated into a slurry containing alumina sol and then heat treated again in an oxidizing atmosphere. delete

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