KR20060084124A - Method for preparing of corrugated ceramic paper and corrugated ceramic paper using the same - Google Patents

Abstract

A method of making corrugated ceramic paper is provided.

The manufacturing method of the corrugated ceramic paper according to the present invention is characterized by improving the dispersion of the fiber and forming uniform pores in the final paper by using the ceramic fiber of the sub-millimeter length, organic fibers or pulp, etc. Even though the auxiliary material of is not used, the moisture content of the green ceramic paper is adjusted first in the pre-corrugation step to maintain the flowability and tensile strength of the green ceramic paper in the corrugation step, thereby optimizing the waveform and then moisture It is possible to maintain excellent the degree of waveform by suppressing the restoration of the corrugated shape by completely drying and then firing it to maintain the strength of the final ceramic paper is excellent. Ceramic paper prepared according to the present invention is excellent in uniformity of pores and excellent in strength.

Ceramic Paper, Pore Uniformity

Description

Method for preparing corrugated ceramic paper and corrugated ceramic paper produced by the same {Method for preparing of corrugated ceramic paper and corrugated ceramic paper using the same}

Figure 1 shows the size and distribution of the pore diameter in the ceramic paper prepared according to Example 1 of the present invention.

Figure 2 shows the size and distribution of the pore diameter in the ceramic patterner prepared by Comparative Example 1.

The present invention relates to ceramic papers, and more particularly, to a method for producing corrugated ceramic paper and a corrugated ceramic paper produced thereby.

Since the late 1970s, a diesel particulate filter (DPF) has been proposed and studied as a device for filtering particulate matter from diesel engines.DPF is divided into honeycomb monolith filter, ceramic fiber filter and metal filter. Can be. Among these, honeycomb monolith filter has a disadvantage of short life because it is vulnerable to high temperature thermal shock, and metal filter has advantages of price and ease of manufacture, but has a disadvantage of heat resistance and corrosion resistance. Research is actively being conducted.

The ceramic fiber filter has a porosity of 80% or more, has excellent ability to collect fine particles of 1 μm or less, and has a strong advantage in thermal shock due to the inherent elasticity of the fiber, and is used in the diesel engine because it can be structured in various forms. In addition to the dust filter may be used as a heat insulating material or a photocatalyst support.

U.S. Patent No. US 5322537 discloses an exhaust gas filter manufactured using aluminosilicate ceramic fibers having a length of 0.1 to 10 mm, but entanglement during dispersion due to the presence of ceramic fibers having a length of up to 10 mm is disclosed. There is a problem that the uniform dispersion of the ceramic fiber is difficult to occur due to the poor uniformity of the pores of the ceramic filter, the overall physical properties of the filter is reduced.

In addition, US Patent Publication No. US 6444006 discloses a ceramic filter manufactured using a ceramic fiber having a length of 0.1 to 10 mm in the same manner as US 5322537, but after completely drying the green ceramic paper in the step before the waveform, Due to the oxidization step, structural breakdown may occur during the corrugation process. To improve this, Kevlar fiber and wood fiber are added to the slurry for forming the green ceramic fiber. Pore size of the rough ceramic paper may be uneven and there is a disadvantage that the strength is poor.

Accordingly, the first technical problem to be achieved by the present invention is to overcome the problems of the prior art to provide a method of manufacturing a ceramic filter having excellent pore uniformity and excellent strength.

The second technical problem to be achieved by the present invention is to provide a ceramic filter manufactured by the above manufacturing method and excellent in uniformity and strength of pores.

The present invention to achieve the first technical problem

(a) preparing a ceramic green paper using a slurry solution of 0.1-1 mm ceramic fiber, silica sol and organic binder;

(b) first drying the ceramic green paper;

(c) corrugating the primary dried ceramic green paper using a corrugating apparatus;

(d) completely drying the corrugated ceramic green paper; And

(e) heat treating the completely dried ceramic green paper to obtain a ceramic paper.

According to an embodiment of the present invention, the ceramic fiber used in step (a) may be alumina or aluminosilicate.

According to another embodiment of the present invention, the content of the silica sol in the step (a) may be 5 to 30% by weight based on the ceramic fiber.                     

In addition, the organic binder of step (a) is an acrylic binder, polyvinyl alcohol, amphoteric starch or a mixture thereof, and the amount of the organic binder may be 5 to 40% by weight based on the silica sol.

According to another embodiment of the present invention, the step of the first drying is performed through a natural drying or a dryer, the content of water in the ceramic green paper after the first drying is 40 to the ceramic green paper at the complete drying It may be ~ 160% by weight.

According to a preferred embodiment of the present invention, in step (d), the length change due to the waveform after completely drying the ceramic green paper may be 10% or more.

In addition, the heat treatment temperature of the step (e) is a manufacturing method of the corrugated ceramic paper, characterized in that 800 ~ 1200 ℃.

The present invention to achieve the second technical problem,

It provides a corrugated ceramic paper, characterized in that produced by the manufacturing method.

According to one embodiment of the present invention, the average flow pore size of the ceramic paper is 4 ~ 6㎛, pores of 2 to 12㎛ size may be present in a ratio of 90% or more of the total pores.

In addition, the bending strength of the ceramic paper is preferably 3400 kPa or more.

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

The manufacturing method of the corrugated ceramic paper according to the present invention is characterized by improving the dispersion of the fiber and forming uniform pores in the final paper by using the ceramic fiber of the sub-millimeter length, organic fibers or pulp, etc. Even though the auxiliary material of is not used, the moisture content of the green ceramic paper is adjusted first in the pre-corrugation step to maintain the flowability and tensile strength of the green ceramic paper in the corrugation step, thereby optimizing the waveform and then moisture It is possible to maintain excellent the degree of waveform by suppressing the restoration of the corrugated shape by completely drying and then firing it to maintain the strength of the final ceramic paper is excellent.

The ceramic fiber used in the present invention may be one containing at least one of alumina or silica such as alumina, alumina silicate, and cut the fiber to a length of 1 mm or less. The length of the cut fiber is preferably 0.1 to 1mm, but if less than 0.1mm, the strength of the produced paper is very weak, and when it exceeds 1mm, it is difficult to uniformly disperse the fiber, which may cause unevenness of the paper. have.

Ceramic green paper in the present invention can be prepared using a papermaking method commonly used in the art, wherein the slurry solution used is prepared by mixing the ceramic fiber with silica sol and a small amount of organic binder. Among the additive components, the silica sol adheres to the prepared paper and serves as an inorganic binder after heat treatment, and the content of the silica sol is 5 to 30% by weight based on the fiber. If the content of the silica sol is less than 5% by weight, the strength of the ceramic paper may be lowered because it may not be entirely coated as an inorganic binder. When the content of the silica sol exceeds 30% by weight, the pore size and porosity in the ceramic paper may be increased by silica. Can be degraded.

Examples of the organic binder that can be used in the present invention include acrylic based polyvinyl alcohol, cationic starch, and mixtures thereof. The organic binder serves to improve the bonding force between the fiber and the fiber and the fiber and the silica sol in the papermaking process. do. The amount of the organic binder may be 5 to 40% by weight based on the silica sol used. When the amount of the organic binder is less than 5% by weight, a large amount of silica sol is lost during the papermaking process because the bonding strength between the ceramic fiber and the silica sol is weakened. There is a concern that the connection between the fiber and the fiber is weak, there is a problem that it is difficult to maintain the structure of the paper. On the other hand, when the usage-amount of the said organic binder exceeds 40 weight%, the fluidity | liquidity of ceramic green paper becomes unnecessarily large and adhesiveness appears, and workability | operativity falls.

The ceramic green paper is manufactured according to a conventional papermaking method using the slurry solution for preparing the ceramic paper prepared above, wherein the excess water is smoothly removed using a vacuum pump connected to the papermaking machine, Excess water can be removed.

The first step of drying the ceramic green paper thus prepared is through natural drying or a dryer, and the content of water in the ceramic green paper after the first drying is 40 to 160% by weight relative to the ceramic green paper upon complete drying. Can be. When the moisture is less than 40% by weight, the flexibility of the ceramic green patter is low, so there is a risk of structural breakdown in the waveform step. When the moisture content is more than 160% by weight, the flowability of the ceramic green patter is too high. There is a problem that waveforms cannot be properly formed due to the highness.

As such, the ceramic green paper is first dried to control moisture, and then the ceramic green paper is put into a wave forming device. The corrugating apparatus is not particularly limited as long as it is conventionally used in the art. For example, the drum of the corrugating apparatus has a length of 2 mm and a 3 mm valley and a pitch, respectively, and is manufactured such that the surface temperature and the feeding speed of the paper are adjustable. Can be used.

The ceramic green paper is corrugated and then completely dried through a secondary drying step. In the present invention, the degree of waveform is measured as a percentage ratio compared to before the waveform by measuring the degree of reduction of the length of the corrugated ceramic paper, and in step (d) the waveform after the ceramic green paper is completely dried It is preferable that the change in length is more than 10%. As the rate of change is larger, the degree of waveforming is increased.

In addition, the heat treatment temperature of the step (e) is preferably 800 ~ 1200 ℃, which is a temperature range in which the silica sol can serve as an inorganic binder, while belonging to the general temperature of the alumina-silica fiber to be used. If the temperature is less than 800 ℃, the strength of the inorganic binder becomes weak because the firing temperature is low, and the inorganic binder does not work properly.When the temperature is above 1200 ℃, the fiber is severely deformed and the original shape cannot be maintained. There exists a possibility that the 2nd crystal phase which adversely affects heat resistance may precipitate from a component.

The average flow pore size of the corrugated ceramic paper prepared according to the present invention is preferably 4-6 μm, and the uniformity of the pores is preferably a pore having a size of 2-12 μm at a rate of 90% or more of the total pores. This is because the case where the pore size is within the above range is suitable for filtering out dust particles while withstanding the pressure of air caused by the flow of exhaust gas.

In addition, the bending strength of the ceramic paper is preferably 3400 kPa or more, but below the numerical value, the durability of the filter may be deteriorated.

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

Example 1

1 g of fiber made of alumina silicate having an average length of 300 μm was added to 500 ml of water, and the mixture was stirred vigorously to disperse the fibers. After the fibers were dispersed, the silica sol was added with 20 wt% of the weight of the fibers, followed by stirring to further disperse evenly. This was done. Next, the positive starch corresponding to 15% by weight (0.03 g) of the silica sol added above is dissolved in water, placed in a slurry in which the fiber is dispersed, and gently stirred to floc by surface charge of the positive starch. At this time, the pH of the entire slurry was about 5.5. Next, the mixture was continuously stirred lightly so that the solids in the slurry were mixed evenly while adding more water so that the total slurry had a capacity of 2L. Then, ceramic paper having a diameter of 9.5 cm and a thickness of 500 μm was manufactured using a papermaking apparatus. The ceramic paper thus prepared was naturally dried as primary drying at room temperature for 30 minutes, and the weight thereof was measured. The ceramic paper was gradually supplied at a rate of 45 cm per minute, and the ceramic paper was contacted in the corrugation apparatus at 90 ° C. or higher to keep the moisture from the paper while drying. The corrugated ceramic paper was dried in a drying oven at 100 ° C, and the mass was measured. Then, the amount of water remaining on the paper during molding was checked. Got a paper. The wave form degree of the paper was evaluated by the change in the length of the bone in the vertical direction. The paper weight after primary drying for 30 minutes at room temperature was 1.93g, the paper weight after complete drying through the corrugation step and the secondary drying step is 1.35g, the moisture content of the first drying 42.96% of the paper weight and the diameter of the paper after corrugation decreased from 9.5 centimeters to 8.5 centimeters, so the rate of change in the length of the bone in the vertical direction was 10.53%, and the average flow pore size was about 5 ㎛, and the size of 2-12 ㎛ The pores were 90% of the total pores and the bending strength was 3800 kPa.

Figure 1 shows the size and distribution of pores in the ceramic paper produced by this embodiment. Referring to this figure, it can be seen that the pore size is very uniform since the distribution of pore sizes is within 2 to 12 μm.

Example 2

Ceramic paper was prepared in the same manner as in Example 1, except that the content of water in the paper was 95% by weight with respect to the completely dried ceramic green paper by drying for 20 minutes in the natural drying conditions when the first drying, The change in length due to corrugation was 12.63%, the average flow pore size was about 5㎛, the pores of 2-12㎛ size were 90% of the total pores, and the bending strength was 3800kPa.

Comparative Example 1

10.5 g of alumina fiber having a length of 0.1 to 10 mm was dispersed in 5 L of water, and a dispersion obtained by dispersing 1.8 g of wood fiber and 1.8 g of Kevlar fiber in 1 L of water was added to the alumina fiber dispersion. Next, after adding 2 g of an acrylic binder, pH was adjusted to 6, 15 L of water was further added, stirred, and ceramic green paper was prepared using a papermaking apparatus. After the ceramic green paper was completely dried at 150 ° C., the ceramic green paper was corrugated using a corrugating apparatus and heat-treated at 1200 ° C. to obtain a final corrugated ceramic paper. The change in length due to the wave form was 9.47%, the average flow pore size was 9 μm, the pores of 2 to 12 μm were about 60% of the total pores, and the bending strength was 1600 kPa. The pore size and distribution in the ceramic paper produced by Comparative Example 1 are shown in FIG. 2. It can be seen that the pore size is nonuniform because the pore size distribution is distributed over 2 to 30 μm. If the pore size is nonuniform, some pores are easily occluded, or the physical properties of the filter manufactured using the There is a problem falling. In addition, the bending strength of the ceramic paper is only 1600kPa, so the durability is very weak.

Comparative Example 2

Ceramic paper was prepared in the same manner as in Example 1 except that the moisture content in the paper was dried at 50 ° C. under natural drying conditions for the first drying to 9.93% by weight based on the completely dried ceramic green paper. The change in length due to the waveform was 7.45%.

Comparative Example 3

A ceramic paper was prepared in the same manner as in Example 1 except that the moisture was completely dried in the first drying process, and the ceramic paper was not maintained after the wave form and structural destruction occurred.

Example 3

Except for using the acrylic binder to give flexibility to the ceramic green paper and the content of moisture in the first drying process 68.47% by weight based on the weight of the fully dried ceramic green paper ceramic in the same manner as in Example 1 Paper was prepared and the change in length by waveform was 11.34%.

Example 4

The ceramic paper was manufactured in the same manner as in Example 3, except that the moisture content during the first drying was 10% by weight based on the weight of the completely dried ceramic green paper, and the change in length due to the wave form was 5.32 Was%.

As described above, according to the present invention, it is possible to excellently control the degree of waveform of the ceramic paper without using the organic fiber, and excellent reproducibility, thereby the ceramic paper is excellent in uniformity of pores and excellent durability. .

Claims (10)

(a) preparing a ceramic green paper using a slurry solution of 0.1-1 mm ceramic fiber, silica sol and organic binder; (b) first drying the ceramic green paper; (c) corrugating the primary dried ceramic green paper using a corrugating apparatus; (d) completely drying the corrugated ceramic green paper; And (e) heat treating the completely dried ceramic green paper to obtain ceramic paper. The method of claim 1, wherein the ceramic fiber used in step (a) is alumina or aluminosilicate. The method of claim 1, wherein the content of the silica sol in the step (a) is 5 to 30% by weight based on the ceramic fiber.        According to claim 1, wherein the organic binder of step (a) is an acrylic binder, polyvinyl alcohol, amphoteric starch or a mixture thereof, the amount of the waveform is characterized in that 5 to 40% by weight based on the silica sol Of the prepared ceramic paper.        The method of claim 1, wherein the first drying step is carried out through a natural drying or a dryer, the content of water in the ceramic green paper after the first drying is 40 to 160% by weight relative to the ceramic green paper at the time of complete drying Method for producing a corrugated ceramic paper, characterized in that.        The method of manufacturing a corrugated ceramic paper according to claim 1, wherein in step (d), the length of the ceramic green paper after the drying is completely changed by the wave form, wherein the change in length is 10% or more.        The method of claim 1, wherein the heat treatment temperature of the step (e) is 800 ~ 1200 ℃ manufacturing method of the corrugated ceramic paper.        A corrugated ceramic paper produced by the method according to claim 1.        The corrugated ceramic paper of claim 8, wherein the average flow pore size of the ceramic paper is 4 to 6 μm, and pores having a size of 2 to 12 μm are present at a rate of 90% or more of the total pores. 9. The corrugated ceramic paper of claim 8, wherein the bending strength of the ceramic paper is at least 3400 kPa.

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