JPS6137227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously producing an alumina fiber molded article and an apparatus therefor.

One of the conventional methods for producing an alumina fiber molded article is, for example, as described in British Patent No. 1098595, in which water is removed from a slurry containing alumina fibers and a colloidal inorganic binder. A method of removing alumina fibers to produce a molded body of alumina fibers is known. However, in order to produce on an industrial scale by this manufacturing method, in order to reduce the loss of inorganic binder during removal of water from the slurry,
The pH of the slurry needs to be maintained at an acidic level of about 3 to 5. Therefore, according to the conventional method, equipment during dehydration is easily corroded, and acidic wastewater must be treated, which causes many problems.

Furthermore, in conventional methods, fixing aids such as polyacrylamide and organic binders such as acrylic latex are required, and due to the presence of these agents, the drying temperature of the molded product must be kept to a maximum of 170°C. Productivity is extremely low.

Furthermore, according to the above specification, in the conventional production method, it is described that a binder is further added to the molded body in a wet state after dehydration, but even if it is added in this way, the molded body It is difficult for the binder to penetrate uniformly into the interior, and adding the binder increases the moisture content of the molded product, making the drying conditions even more unfavorable.

Therefore, the present inventors conducted extensive research, and as a result, provide a method and an apparatus for producing an alumina fiber molded article without using any acids, organic substances, etc., as in the conventional method described above.

That is, the method of the present invention involves dehydrating alumina fiber-containing mat or the like to a moisture content of 100 to 300% to form a molded body, then spraying the molded body with a liquid containing a binder, and then further Moisture content of molded body is 100
It is characterized by dehydration to ~300%.

Further, the apparatus according to the present invention has at least two dewatering zones arranged along a continuously moving movement track, and a means for spraying a liquid containing a binder is provided between these dewatering zones, so that each dewatering In the zone,
It is characterized in that a compression molding means for compression molding the alumina fibers and the like on the moving track is attached.

Next, the present invention will be explained in detail.

First, the drawing is a layout diagram of a part of an example of an apparatus for carrying out the present invention. As shown in this drawing, a moving track 1 usually consisting of a net conveyor moves continuously in the direction of arrow A. At least two dewatering zones 2, 3 are arranged along the dewatering system 1, and a spraying means 4 is provided between these two dewatering zones 2, 3.

Further, compression molding means 5, 6 such as a roller conveyor consisting of a plurality of press rolls are attached to each dewatering means, especially each dewatering zone 2, 3 before and after the spraying means 4, and furthermore, a moving track 1 A press roll 7 or the like is provided on the leading side of the roll. In the manufacturing apparatus having such a configuration, when the mat 8 containing alumina fibers is placed on the moving track 1 and moved, the alumina fiber molded bodies are sequentially dehydrated. It can be manufactured continuously through processes such as spraying.

To explain in more detail, first, alumina fibers are put into water and stirred, and the alumina fibers are opened and made into a slurry, and then water is removed from the slurry to an extent that the shape can be maintained to form matte. The water-containing mat 8 is placed on the moving track 1 and continuously fed. In this case, the alumina fibers to be treated usually contain 70 to 100% by weight of Al ₂ O ₃ with the remainder consisting of SiO ₂ , MgO, Fe ₂ O ₃ , Na ₂ O, etc., and have a fiber diameter of 0.1% by weight. ~10μm,
The majority are single fibers of 2 to 4 μm.

Next, the water-containing mat 8 is sent along with the moving track 1 such as a net conveyor to the first dehydration zone 2.
to go into. In this primary dehydration zone 2, a compression molding means 5 such as a press roll is passed through a moving track 1.
Therefore, the water-containing mat 8 is continuously dehydrated in the dewatering zone 2 while maintaining airtightness.

Next, after passing through the first dehydration zone 2, the mat 8
The liquid reaches the spraying means 4, and the spraying means 4 sprays a liquid containing the binder onto the surface of the mat 8. The spraying means 4 is usually configured in an L-shape, and its tip is configured to spray the liquid all over the entire surface of the mat 8 while reciprocating in the width direction of the mat 8.

Next, the moisture increased by the spraying by the spraying means 4 is removed, and a liquid containing a binder is impregnated into the mat 8, and in particular, in order to ensure that the binder is evenly distributed, a second Next, dehydration is carried out in dehydration zone 3. In this dewatering zone 3 as well, compression molding means 6 is provided as in the primary dehydrating zone 2, and the mat 8 is subjected to secondary dewatering. Further, the mat 8 after the secondary dehydration is fed into a press roller 7 to finally adjust the thickness, and then dried through a dryer or the like to obtain a molded body of alumina fibers.

As described above, a molded article of alumina fibers is produced by processing matte, etc. containing alumina fibers. Preferably, the process and composition is as follows.

That is, alumina fiber has a high true fiber specific gravity, unlike glassy raw cotton such as rock wool and ceramic fiber. Therefore, during the above treatment, it is necessary to increase the specific gravity of the pine and reduce the porosity to eliminate air intake in each dehydration zone. Furthermore, unlike the above-mentioned glass fibers, since the fibers do not originally contain shots of unfiberized particles, the shots are not entrained in the recovered water during dehydration. For this reason, as mentioned above, the pine enters the first dehydration zone in a highly moist state, where it is dehydrated to a dehydration rate of 100-300% and simultaneously compressed by compression molding means, after which a binder is applied by spraying means. The pine that has been sprayed with a liquid containing pine enters a secondary dehydration zone, where it is dehydrated to a dehydration rate of 100 to 300% and at the same time compressed by compression molding means. Binders to promote penetration.

In addition, at this time, if the spraying means 4 is capable of spraying the spraying liquid over the entire surface of the mat,
Although it can be configured in either way, it is usually configured as shown in the figure.
The horizontal part 4a of this tube is oriented in the direction of movement of the mat 8, and a nozzle is formed below the horizontal part 4a, so that the horizontal part 4a can reciprocate in the width direction of the mat 8. It is preferable to configure.

In addition, in the horizontal part, the moving speed of the pine is 5 to 50 cm/
When the length is about 10 to 20 mm, preferably about 50 to 100 mm, the width of the mat is 30 to 150 mm.
cm, it is preferable to reciprocate about 5 to 25 times per minute.

In addition, in each dehydration zone, the water content is dehydrated in the first stage to about 100 to 300%, and then in the second stage, the water content increased by the spraying liquid is dehydrated again to about 100 to 300%. Each dehydration zone must be sufficiently forcibly dehydrated. For this reason, each of the dehydration zones 2 and 3 is configured to be depressurized and forcibly dehydrated, and in particular, the primary dehydration zone 2 is configured to have a length of 10 to 40 cm in the direction of movement of the mat 8. A porous plate is provided on the upper surface of the dehydration zone 2 so that dehydration can be performed under reduced pressure from each pore. In this case, the diameter of the pores in the porous plate is 1 to 5 mm.
It is sufficient to distribute the pores with a pitch of about 5 to 20 mm in φ, and the pressure in the water is -100 to -100 in gauge pressure.
It is sufficient to maintain it at −400 mmHg. In addition, the length of the mat 8 in the second dehydration zone 3 in the moving direction is 5 to 20 cm, and the diameter of the pores of the porous plate is 1 to 5 mm.
The pitch of φ is preferably 5 to 20 mm, and the pressure is preferably maintained at about -200 to -500 mmHg in gauge pressure.

Further, in each dehydration zone having the above configuration, for example, a roller conveyor is provided as the compression molding means 5 in the first dehydration zone 2.
When roller conveyors are arranged like this,
The mat 8 is compressed during dewatering, and this also improves airtightness.

Similarly, roller conveyors are arranged as compression molding means 6 in the second dewatering zone 3, and the airtightness of the mat is similarly improved, but these compression molding means are not necessarily effective in improving the airtightness of the mat other than the roller conveyor. If enhanced, it can be configured either way.

The thickness of the dehydrated pine is adjusted as described above, and then dried in a conventional manner to obtain a molded body made of polycrystalline alumina fibers.

In addition, when processing as described above, the alumina fibers, especially short fiber raw cotton, are first decomposed in water to form a slurry, and this slurry is dehydrated and made into a mat shape before being processed. I can handle it without it. Therefore, for example, any material formed by dehydrating the slurry using a vacuum forming machine, fourdrinier machine, circular paper machine, compression molding machine, etc. may be used, and in addition to mat shape, it may be formed into, for example, board, paper, felt, or sheet. , block, etc. may be used. Further, the moving track does not necessarily need to be configured as a net conveyor, but can be configured in any manner as long as the mat etc. can be moved continuously and dewatering treatment etc. can be performed during this time.

Next, examples will be described.

Example 1 20 kg of alumina fibers with a true specific gravity of 3.5 and a fiber diameter of 3 μm were put into 4 m ³ of water and stirred to uniformly open the fibers, and the resulting slurry had a pH of 7.0. This slurry was fed to a fourdrinier machine at a feed rate of 50/min to form a wet mat. This pine was treated with the equipment shown. At this time, the feed speed of the net conveyor 1 was 10 cm/min, the width of the mat was 100 cm, and the binder was a mixture of alumina sol #200 manufactured by Nissan Chemical Co., Ltd. and Snowtex-O. At this time, the ratio of A ₂ O ₃ :SiO ₂ was 1:1, this mixture was contained at 5%, and this liquid was sprayed at a spraying speed of 0.5/min.

Also, the gauge pressure in the primary dehydration zone 2 is -250
The sample was dehydrated by suction at mmHg, and the moisture content after passing through the first dehydration zone 2 was 250%. Further, the gauge pressure in the second dehydration zone 3 was -350 mmHg, and the water content after passing through was 220%. After drying, the formed board had a bulk specific gravity of 0.15, a thickness of 20 mm, and a pure white, uniform board with a bending strength of 5 Kg/cm ² .

Example 2 Slurry similar to Example 1 was transferred to a circular mesh forming machine10
A wet sheet was formed by feeding the liquid at a feed rate of /min. This sheet was conveyed using the net conveyor 1 of the illustrated apparatus at a feed rate of 20 cm/min and a width of 100 cm, and the spraying liquid containing the binder of Example 1 was sprayed at a rate of 60 c.c./min. After drying the formed paper treated in this way, the paper has a bulk specific gravity of 0.15 and a thickness of 2.
It was a pure white paper with flexibility.

The fixation rate of the binder was 70%, and the amount of binder recovered in the secondary dewatering zone was the same as that used for diluting the binder spray stock solution.

As explained in detail above, the present invention is to produce a molded article by dehydrating alumina fiber-containing mat, etc., spraying it with a liquid containing a binder, and then dehydrating it again. No auxiliaries or binders are used, and therefore the drying temperature is 180℃.
A pure white fiber molded product can be obtained even if the process is carried out at temperatures above ℃,
There are no problems with drying.

Furthermore, the binder can be uniformly distributed on the surface and inside the molded body. Furthermore, the fibers of this molded product have an extremely high heat resistance of approximately 1600℃, and it also has excellent wind speed resistance, heat insulation, and spalling resistance properties, so it can be used as a refractory for lining high-temperature industrial furnaces, or as a high-temperature refractory. Suitable as insulation packing.

[Brief explanation of the drawing]

The drawing is a layout diagram of an example of an apparatus for carrying out the present invention. Symbol, 1... Moving orbit, 2... First dehydration zone, 3... Second dehydration zone, 4... Spraying means, 4
a...Horizontal part, 5, 6...Compression molding means, 7...Press roll, 8...Matsu.

Claims (1)

[Claims] 1. Mats, etc. containing alumina fibers are made with a moisture content of 100.
It is characterized by dehydrating to a moisture content of ~300% to form a molded body, then spraying a liquid containing a binder onto this molded body, and then further dehydrating the molded body to a moisture content of 100 to 300%. A method for producing an alumina fiber molded article. 2. At least two dehydration zones are arranged along a continuously moving moving track, while a means for spraying a liquid containing a binder is provided between these dehydrating zones, and each dehydrating zone is provided along the moving track. An apparatus for producing an alumina fiber molded article, characterized in that it is equipped with a compression molding means for compression molding the above alumina fiber, etc.