JP2001335379A - Method of making fiber formed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of making a large fiber formed body of which an inorganic binder is not migrated to the surface, a sufficient strength under a high temperature is employed and especially a thickness is above 100 mm by a simple method without needing special equipment. SOLUTION: A ceramic fiber is mixed with the powder of an ionic organic binder and after the water containing a heat resistant inorganic binder is added and mixed so as to nearly get a wet condition in whole, the wet mixture is filled in the form, pressurized and formed. The ionic organic binder is selected from gelatinized starch, CMC, a polymer flocculant or a polymer dispersant having a cationic or anionic property and the ionic organic binder of 1 to 10 pts.wt. is added to the ceramic fiber of 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber molded product comprising a ceramic fiber and a heat-resistant inorganic binder, which are bonded to each other with an organic binder.
The present invention relates to a method for producing a large-sized fiber molded article having a thickness of at least m.

[0002]

2. Description of the Related Art Conventionally, molded articles made of ceramic fibers have been used as burner tiles, furnace lining materials, tundishes, etc. because of their high melting points and low wettability with molten metals.

[0003] Such a fiber molded body has conventionally been generally produced by the following method. That is, a ceramic fiber and an inorganic binder such as alumina sol and silica sol are suspended in water, and an organic binder such as starch is added to the suspension to cause aggregation, and the fiber and other flocs are formed while being dehydrated. Specific dehydration molding methods include dehydration molding by suction, dehydration molding by centrifugal force, and dehydration molding by pressurization with a high-pressure pump.

[0004] In addition to the above-mentioned molding method, a method of adding a large amount of an organic binder to a ceramic fiber and an inorganic binder such as alumina sol or silica sol to form a slurry and subjecting the slurry to injection molding, Instead, a method of molding using a thermosetting resin is known, but it is not generally adopted.

[0005]

Among the above-mentioned conventional methods for producing a fiber molded body, the method of dehydrating fiber flocks, which is the mainstream method, is a simple method. There is a problem that becomes difficult.
That is, in the dehydration molding, as the thickness of the molded body increases, the filtration resistance increases, and dehydration becomes difficult. Therefore, when considering that the production time increases and the cost increases, the thickness is generally reduced. Only a fiber molded body of about 100 mm at the maximum could be produced.

Therefore, conventionally, when a large-sized fiber molded body having a thickness of 100 mm or more is manufactured, a number of thin fiber molded bodies are laminated and bonded using a mortar or the like. For this reason, the production of a large-sized fiber molded article of a thick deformed product such as a burner tile has been extremely complicated and time-consuming, and has been a major factor in cost increase.

[0007] Even with the injection molding method, it has been difficult to form a large fiber molded article in relation to a mold.
In addition, the apparatus becomes large-scale, and a large amount of an organic binder is required to be degreased, so that the process is complicated and an inexpensive product cannot be obtained.

Further, in the method of obtaining a molded article using a thermosetting resin, when heated during use, the resin is burned and removed, so that the strength of the molded article is significantly reduced. In addition, even when an inorganic binder such as colloidal silica is used in combination, the inorganic binder migrates to the surface during drying and is unevenly distributed on the surface side, so that there is a problem that the strength at high temperatures is reduced.

The present invention has been made in view of such conventional circumstances,
By a simple method that does not require special equipment, it is possible to produce an inexpensive fiber molded body having sufficient strength at high temperatures without the surface migration of an inorganic binder, particularly a large fiber molded body having a thickness of 100 mm or more. The aim is to provide a method.

[0010]

Means for Solving the Problems To achieve the above object, a method for producing a fiber molded article provided by the present invention comprises:
The ceramic fiber is mixed with the ionic organic binder powder, and water containing a heat-resistant inorganic binder is added and mixed so that the whole becomes almost wet. Then, the wet mixture is filled in a mold and pressed to be molded. It is characterized by doing.

[0011] In the method for producing a fiber molded article of the present invention, the ionic organic binder may be any one of a pregelatinized starch, a CMC, a polymer flocculant, and a polymer dispersant having a cationic or anionic property. It is characterized by being. Further, the amount of the ionic organic binder powder to be added is 1 to 10 parts by weight based on 100 parts by weight of the ceramic fiber.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a fiber molded article according to the present invention, a wet mixture containing a ceramic fiber, an ionic organic binder powder and a heat-resistant inorganic binder is prepared, filled into a mold and added. Since the pressure molding is performed, the dehydration molding which is indispensable for the conventional general method is not required.
Therefore, there is no limitation on the thickness of the molded article due to the filtration resistance during dehydration, and a large fiber molded article having a thickness of 100 mm or more can be easily manufactured.

In the present invention, the ceramic fibers and the heat-resistant inorganic binder to be used may be those conventionally used in this type of fiber molded article. For example, as the ceramic fiber, alumina silica fiber, mullite fiber, alumina fiber, or the like can be used. Further, the heat-resistant inorganic binder is used to maintain the strength of the molded body even after the organic binder has disappeared by firing, for example, alumina sol, silica sol, oxides that are sintered at a low temperature such as titania sol are used. You.

[0014] The ionic organic binder used in the present invention swells or dissolves by the addition of water to bind the ceramic fiber and the heat-resistant inorganic binder to each other, thereby imparting shape retention to the molded article. It is. In addition, by imparting ionicity (anionic or cationic) to the organic binder, a heat-resistant inorganic binder can be fixed to the surface of the organic binder to prevent the inorganic binder from migrating to the surface of the molded body. Therefore, it is possible to obtain a homogeneous fiber molded body having no variation in strength after firing or at a high temperature.
In the present invention, a powder of an ionic organic binder is used in order to enhance the mixing property with the ceramic fiber.

As such ionic organic binder powders, there are those obtained by imparting ionicity such as anionicity or cationicity with pregelatinized starch, CMC (carboxymethylcellulose), polymer flocculant, polymer dispersant and the like. And one or more of these can be used in combination. Among these, the pregelatinized starch is preferred because it swells immediately with water to exhibit a sizing property and is excellent in shape retention. The types of starch include rice starch,
Any of corn starch, potato starch, tapioca and the like may be used.

The method according to the present invention will be described in the order of steps.
First, a ceramic fiber and an ionic organic binder powder such as pregelatinized starch are mixed, and the organic binder powder is uniformly dispersed in the fiber while the ceramic fiber is defibrated. After uniformly mixing and dispersing the ceramic fiber and the ionic organic binder powder, add the heat-resistant inorganic binder diluted by adding water, and further mix so that the solution spreads over the entire mixture of the ceramic fiber and the ionic organic binder. I do.

Incidentally, depending on the ionicity of the organic binder,
Preferred heat-resistant inorganic binders are used in combination. For example, colloidal silica or silica sol is used as an inorganic binder for a cationic organic binder, and alumina sol is used for an anionic organic binder.
The titania sol of the inorganic binder can be used for both cationic and anionic organic binders.

The mixer used for mixing the above-mentioned ceramic fiber and the ionic organic binder powder only needs to have the ability to defibrate the fiber and the ability to uniformly disperse the powder in the fiber. For example, a Ladige mixer, a Henschel mixer , An omni mixer, a ribbon mixer, or the like. The subsequent mixing of the heat-resistant inorganic binder can also be performed continuously using the same mixer.

The amount of the ionic organic binder added is
The range is preferably 1 to 10 parts by weight based on 100 parts by weight of the ceramic fiber. If the amount of the ionic organic binder powder is less than 1 part by weight, the shape retention of the molded product is not sufficient, and if it exceeds 10 parts by weight, the ceramic fibers are sticky with the organic binder or the ceramic fibers are excessively agglomerated. Occurs, making molding difficult.

The amount of water (without inorganic binder) added is
The mixture is adjusted so as to be almost wet, but generally 3 parts per 100 parts by weight of ceramic fiber.
The content is preferably in the range of 0 to 200 parts by weight. Water is necessary for swelling or dissolving the ionic organic binder to develop moldability. However, if the amount is less than 30 parts by weight with respect to 100 parts by weight of the fiber, moldability cannot be obtained.
If the amount exceeds 00 parts by weight, excess water is excessively increased, which is not preferable.

The heat-resistant inorganic binder is necessary to maintain the strength of the fiber molded product even after the organic binder has disappeared due to high temperature during use.
If the amount is less than 1 part by dry weight without water, sufficient strength cannot be obtained. Conversely, when the amount exceeds 20 parts by weight, the amount of the inorganic binder remaining in the molded body is determined by the amount of the organic binder, so that the inorganic binder not bound to the organic binder migrates to the surface during drying. As a result, only the strength of the surface is improved. Therefore, the amount of the inorganic binder to be added to 100 parts by weight of the fiber is preferably in the range of 1 to 10 parts by weight in terms of dry weight.

The mixture of the ceramic fiber, the organic binder, and the inorganic binder prepared as described above is filled in a molding die while being almost entirely wet, and is molded under pressure. Specifically, it is pressed into a predetermined shape by squeezing from an opening of the mold, or is press-formed into a predetermined shape using a uniaxial press or the like.

As described above, if the amount of water is adjusted to 200 parts by weight or less based on 100 parts by weight of the ceramic fiber, excessive dehydration of water during pressure molding is almost eliminated.
If left for a few seconds, the shape retention of the molded body is increased. In particular, when pregelatinized starch is used as an organic binder, excess water is absorbed and disappears. After demolding, the product is further dried, and if necessary, further fired at a temperature of about 700 ° C. or more to obtain a final fiber molded product.

Since the fiber molded body thus manufactured has sufficient strength as it is, has a high melting point and is hardly wetted by molten metal, it can be used as a burner tile, a furnace lining material, a tundish, or the like. Are offered as various products. Further, the organic binder is burned off during use or firing at a high temperature, but at the same time, the heat-resistant inorganic binder reacts with the ceramic fiber and bonds with each other, so that sufficient strength as a fiber molded body can be maintained. .

In the present invention, a finely crushed fiber product such as a used blanket or fiber board can be used in place of a part of the ceramic fiber as a raw material. Therefore, fiber products such as used blankets and fiber boards which have been conventionally treated as industrial waste can be recycled and reused.

When mixing the ceramic fiber and the heat-resistant inorganic binder, various additives such as oxides or non-oxides may be added and mixed as a partial substitute for these raw materials or for improving the properties. Can be. In particular, by adding and mixing the clay, the strength of the fiber molded body can be further improved, and the amount of the inorganic binder added can be reduced, so that the cost can be reduced.

Further, in the mixing step of the ceramic fibers, the bulk specific gravity of the obtained fiber molded article is changed by changing the fiber opening time (mixing time with the inorganic binder and the organic binder) and / or the rotation speed of the mixer. Can be changed in the range of 0.15 to 0.6.

[0028]

【Example】Example 1  Cationic to 100 parts by weight of ceramic fiber
Add 4 parts by weight of pregelatinized starch and mix for 1 minute
For a while. Then, 100 weight of ceramic fiber
2 parts by weight of silica sol to water
100 parts by weight of this aqueous solution (ceramic fiber 1
98 parts by weight of water only relative to 00 parts by weight)
Was added and mixed for an additional minute with a Lodige mixer.

The resulting wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity was measured to be 0.24, and the flexural strength was 0.30 MPa. When this fiber molded body was fired at 700 ° C. for 3 hours, the bulk specific gravity did not change and the bending strength was 0.22 MPa.

[0030]Example 2  Cationic to 100 parts by weight of ceramic fiber
Add 5 parts by weight of pregelatinized starch and mix for 1 minute with a Lodige mixer
For a while. Then, 100 weight of ceramic fiber
Add silica sol to water so as to be 4 parts by weight
164 parts by weight of this aqueous solution (ceramic fiber 1
160 parts by weight as water only with respect to 00 parts by weight
Part) and mix for an additional 1 minute with a Lödige mixer.
Was.

The resulting wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, and the bulk specific gravity was measured to be 0.33, and the flexural strength was 0.25 MPa. When this fiber molded body was fired at 700 ° C. for 3 hours, the bulk specific gravity did not change and the bending strength was 0.22 MPa.

[0032]Example 3  Cationic to 100 parts by weight of ceramic fiber
5 parts by weight of neutralized pregelatinized starch and 20 parts by weight of dry clay powder were added.
Then, the mixture was mixed for 1 minute using a Lodige mixer. Then,
4 parts by weight for 100 parts by weight of lamic fiber
Silica sol is added to water so that
Parts by weight (water per 100 parts by weight of ceramic fiber)
96 parts by weight).
Mix for an additional minute with the mixer.

The resulting wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity is 0.4, and the bending strength is 0.32.
MPa. When this fiber molded body was fired at 700 ° C. for 3 hours, the bulk specific gravity did not change and the bending strength was 0.26 MPa.

[0034]Example 4  Use crushed to 50 parts by weight of ceramic fiber
50 parts by weight of the used blanket
5 parts by weight of cationic pregelatinized starch are added to
Mix for 1 minute with a Lödige mixer. Then the cerami
100 weight of check fiber and used blanket
Add silica sol to water so that it becomes 4 parts by weight to
100 parts by weight of this aqueous solution (ceramic fiber
96 weight as the addition amount of water only to 100 weight parts
Part) and mix for an additional 1 minute with a Lödige mixer.
Was.

The resulting wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity is 0.36, and the bending strength is 0.2.
It was 8 MPa. This fiber molded body is heated at 700 ° C. for 3 hours.
When calcined for an hour, the bulk specific gravity did not change, and the bending strength was 0.20 MPa.

[0036]Example 5  Anionic to 100 parts by weight of ceramic fiber
8 parts by weight of pre-gelatinized starch and add 1 minute with a Lodige mixer
For a while. Then, 100 weight of ceramic fiber
Alumina sol was added to water so as to be 6 parts by weight with respect to
110 parts by weight of this aqueous solution (ceramic fiber
The amount of water only added to 100 parts by weight is 104
Parts) and mix for an additional minute with a Lodige mixer.
did.

The obtained wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity was measured to be 0.30, and the flexural strength was 0.20 MPa. When this fiber molded body was fired at 700 ° C. for 3 hours, the bulk specific gravity did not change and the bending strength was 0.14 MPa.

[0038]Example 6  Cationic to 100 parts by weight of ceramic fiber
Add 3 parts by weight of CMC and mix for 1 minute with a Lodige mixer
Mixed. Then, 100 parts by weight of ceramic fiber
Add silica sol to water so that it becomes 6 parts by weight
100 parts by weight of this aqueous solution (ceramic fiber 1
94 parts by weight of water only per 100 parts by weight)
Was added and mixed for an additional minute with a Lodige mixer.

The obtained wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity is 0.50, and the bending strength is 0.5.
It was 40 MPa. 700 ° C.
, For 3 hours, the bulk specific gravity did not change and the bending strength was 0.24 MPa.

[0040]Example 7  Cationic to 100 parts by weight of ceramic fiber
4 parts by weight of a gum-based polymer flocculant
Mix in sir for 1 minute. Then ceramic fiber
Silica sol so that it is 4 parts by weight for 100 parts by weight
Was added to water, and 100 parts by weight of this aqueous solution (ceramic film) was added.
The addition amount of water alone to 100 parts by weight of fiber is 9
6 parts by weight) and add another 1 minute with a Lodige mixer
Mixed.

The obtained wet mixture is placed in a mold,
Press molded. The fiber molded body obtained by drying after demolding is 200 mm long × 200 mm wide × 200 mm thick.
mm, the bulk specific gravity is 0.43, and the bending strength is 0.4.
It was 40 MPa. 700 ° C.
, The bulk specific gravity did not change and the bending strength was 0.21 MPa.

[0042]

According to the present invention, an inexpensive fiber molding method which does not require special equipment and does not involve dehydration, has no surface migration of the inorganic binder and has sufficient strength at high temperatures. In particular, a large-sized fiber molded body having a thickness of 100 mm or more, which can be produced only by pasting, can be easily produced as an integrated body.

Also, used fiber products such as fiberboard and blanket used for the furnace material can be reused as a part of the raw material, so that the recycling reduces the cost and the amount of industrial waste. Can contribute.

Claims (6)

[Claims] 1. A method for producing a fiber molded body comprising a ceramic fiber and a heat-resistant inorganic binder which are mutually bonded by an organic binder, wherein the ceramic fiber is mixed with an ionic organic binder powder, A method for producing a fiber molded article, comprising adding and mixing water containing an inorganic binder so that the whole is almost wet, filling the wet mixture in a mold, and pressing and molding. 2. The method according to claim 1, wherein the ionic organic binder is any one of a pregelatinized starch, a CMC, a polymer flocculant, and a polymer dispersant having cationic or anionic properties. The method for producing a fiber molded article according to the above. 3. The method according to claim 1, wherein the amount of the ionic organic binder powder is 1 to 10 parts by weight based on 100 parts by weight of the ceramic fiber.
The method for producing a fiber molded article according to the above. 4. The method according to claim 1, wherein the amount of water is 30 to 200 parts by weight based on 100 parts by weight of the ceramic fiber. . 5. The method according to claim 1, wherein the addition amount of the heat-resistant inorganic binder is 1 to 20 parts by weight on a dry weight basis with respect to 100 parts by weight of the ceramic fiber.
The method for producing a fiber molded article according to any one of the above. 6. The method for producing a fiber molded product according to claim 1, wherein a part of the used fiber product is finely crushed in place of the ceramic fiber. Method.