JPH0735608B2 - Method for producing alumina-silica fiber precursor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing an alumina-silica fiber precursor,
In particular, it relates to a method for producing a high-quality alumina-silica fiber precursor containing almost no non-fibrous material (hereinafter referred to as shot).

[Prior Art] In recent years, alumina-silica short fibers have attracted attention as a lightweight heat insulating material for high temperatures usually at 1300 ° C or higher, and various manufacturing methods thereof have been proposed.

For example, JP-B-44-17751 discloses that an aluminum compound containing no organic polymer, 4,000 to 4,500 cp.
A method for producing an alumina-silica heat-resistant fiber has been reported by spinning a fiber stock solution having a high viscosity as described in 1. above using a nozzle in which a small-diameter hole is provided directly at the peripheral end of a rotating disk.

On the other hand, although alumina-silica short fibers have been considerably researched for use in composite materials such as FRM, in this case, shots contained in a small amount in the alumina-silica short fibers, which is hardly a problem in high-temperature heat insulating material applications, are FRM. It adversely affects the strength and wear resistance of the product. Similarly, in many cases, the shot quality is a problem in terms of expanding the applications of alumina silica short fibers.

[Problems to be Solved by the Invention] In such a case, it is desirable to use long fibers that do not contain shot quality, but since it is considerably disadvantageous in terms of economy as compared with short fibers, shot fibers are generally used. Alumina-silica short fibers are usually purified and used to remove quality beforehand. Further, in general, it is possible to reduce the shot amount to some extent by reducing the spinning ability to some extent, which is common to ordinary spinning methods. However, the shot amount contained in the alumina-silica short fibers is still about 3 to 5% by weight. Is the limit.

Further, Japanese Patent Publication No. 17751/44 does not disclose any method for producing high quality alumina-silica short fibers containing almost no shot matter.

The present invention has been completed as a result of earnest research in view of such actual circumstances, contains almost no shot quality, and can be directly used for FRM or inorganic paper for which shot quality is unfavorable. It is an object of the present invention to provide a method for producing a high-quality alumina-silica fiber precursor which can be produced at a price almost equal to the fiber cost.

[Means for Solving Problems] That is, the present invention provides a high-quality alumina-silica fiber precursor containing almost no non-fibrous material from a fiber stock solution composed of a mixed solution of an aluminum compound aqueous solution containing an organic polymer and a silica compound. In the method of producing, the viscosity 1500 ~ 3500
It is characterized in that the fiber stock solution of cp is spun using a plurality of nozzles having an inner diameter of 0.2 to 0.4 mm and a spinning hole depth to inner diameter ratio of 5 to 20 provided at the peripheral end of a hollow rotating disk. It is a method for producing an alumina-silica fiber precursor.

Hereinafter, the present invention will be described in detail.

In the present invention, the alumina-silica fiber is an inorganic fiber having an Al ₂ O ₃ content of 70% by weight or more and an SiO ₂ content of 30% by weight or less, and the alumina-silica fiber precursor is immediately after spinning the fiber stock solution under specific conditions. The fibrous substance of 1) refers to the one that still contains water and organic substances.

In the present invention, the fiber stock solution is a mixture of an aqueous solution of an aluminum compound such as aluminum oxychloride and an aqueous solution of a silica compound such as silica sol, and an organic polymer such as polyvinyl alcohol, and an additive is further added if necessary. Refers to the one that has been concentrated and adjusted to a predetermined viscosity.

In the present invention, the aluminum compound may be one or more selected from aluminum basic chlorides, basic acetates and basic nitrates. Among these, the basic chloride of aluminum is represented by the rational formula Al ₂ (OH) nClm.
(However, aluminum oxychloride represented by n + m = 6) is preferable.

In the present invention, the organic polymer may be any one as long as it imparts a spinning assisting effect to the fiber stock solution, and is preferably a medium or high molecular weight one such as polyvinyl alcohol, partially saponified polyvinyl alcohol, or polyvinyl acetate. The water-soluble polymer having an average degree of polymerization of about 1700 to 2000 is preferable.

In the present invention, an oxide such as magnesium, boron or phosphorus may be used as an additive that imparts preferable physical properties to the alumina-silica fiber. Furthermore, a silicon-based or alcohol-based antifoaming agent may be added to the fiber stock solution.

The fiber stock solution in the present invention is a mixture of an aqueous solution of an aluminum compound containing the above organic polymer and an aqueous solution or colloidal solution of a silica compound and an additive, and concentrated under reduced pressure to adjust the viscosity to impart the necessary spinnability. Spinning is performed.

It is desirable that the fiber stock solution retains the spinnability for several days or more. However, in order to maintain such stable spinnability,
It is affected by pH, water-soluble organic polymer, aluminum compound, silica compound and kinds of additives, blending ratio of each component, viscosity and the like.

When aluminum oxychloride is used as the aluminum compound, the molar ratio of A1 / C1 is 1.5 to 2.2, preferably 1.7 to 1.9, and if the molar ratio is less than 1.5, the alumina solid content is small and spinning is disadvantageous. If it exceeds, the property of the solution becomes unstable.

The content of the organic polymer in the fiber stock solution in the present invention is 1 to 10% by weight, preferably 5 to 8% by weight based on the inorganic solid content, and if it is less than 1% by weight, there is no spinning assisting effect.
Even if it exceeds 10% by weight, the spinnability effect does not change and it is uneconomical.

Further, the content of the aluminum compound in the fiber stock solution is 70% by weight or more based on the inorganic solid content, preferably 72 to 95% by weight, and the content of the silica compound is 30% by weight or less based on the inorganic solid content. , Preferably 5 to 28% by weight is desirable.

The method for producing an alumina-silica fiber precursor of the present invention is a fiber stock solution prepared as described above, a plurality of fiber stock solution projecting on the fiber stock solution outlet side of a ring-shaped nozzle plate provided at the peripheral end of a hollow rotating disk. Spinning is preferably performed using a protrusion nozzle.

The spinning method will be described more specifically by showing one embodiment of the production method of the present invention, and the inner diameter of the nozzle will be about 0.2 mm.
Approximately 0.4 mm and a spinning apparatus equipped with a plurality of projecting nozzles having a ratio of the depth of the spinning hole to the inner diameter of the nozzle of 5 to 20 at the peripheral end portion of the rotating disk, and the fiber stock solution containing the above-mentioned compound. , The viscosity at 20 ° C. is adjusted to 1,000 to 10,000 cp, preferably 1,500 to 3,500 cp and then introduced, and when the fiber stock solution introduced into the rotary disk passes through the nozzle hole and is spun, it is almost shot. In order to give a sufficient pressure to the fiber stock solution inside the rotating disk so as to be spun in a state of not containing, the peripheral speed of the peripheral end of the rotating disk is 30 to 60 m / sec, preferably 37 to 52 m / sec. Spinning is performed by applying a certain number of rotations to the rotating disk and passing it through a protruding nozzle.

The inner diameter of the protrusion nozzle is preferably about 0.2 mm to about 0.4 mm, preferably 0.25 to 0.35 mm.If it is less than about 0.2 mm, the nozzle diameter is too small and clogging easily occurs. It is inferior in nature and causes shots.

The ratio of the depth of the spinning hole to the inner diameter of the nozzle is preferably 5 to 20, preferably 10 to 15, and if it is less than 5, spinnability is poor and shots are generated. If it exceeds 20, clogging of the protruding nozzle occurs. It is easy to do and becomes an obstacle during spinning.

The fiber stock solution is generally advantageous in terms of production capacity because it contains a large amount of inorganic solid content as the viscosity increases. However, in the present invention, the fiber stock solution is spun through a small-diameter nozzle hole, so that
Viscosity at 20 ℃ is 1,000 ~ 10,000cp, preferably 1,5
00 to 3,500 cp is desirable. If it is less than 1,000 cp, the spinnability is inferior and it causes shots. If it exceeds 100,000 cp, the projection nozzle is easily clogged, which causes shots and causes troubles.

Further, when the characteristics of the fiber stock solution used in the present invention were examined in detail, it was found that when the viscosity was about 1,000 cp or more, the increase in the solid content with the increase in the viscosity did not increase so much as to greatly affect the production capacity. .

For example, the undiluted solid content of alumina-silica fiber having Al ₂ O ₃ content of 80% by weight and SiO ₂ content of 20% by weight has viscosities of 1,000 cp and 10,000 c.
There is only a 3% difference in the stock solution from p. Furthermore, since the stability of the fiber stock solution and the maintenance surface of the small-diameter protruding nozzle portion of the rotating disk are generally better as the low-viscosity stock solution is used, the spinning method of the present invention is good and stable with almost no shot quality. In order to obtain the spinnability, the viscosity of the fiber stock solution to be spun under the above-mentioned conditions of the nozzle hole should be 1,000 to 10,000
It is preferably in the relatively low viscosity range of 0 c.p., preferably 1,500 to 3,500 cp.

The peripheral speed of the peripheral edge of the rotating disk is 30 to 60 m / sec, preferably
37 to 52 m / sec is desirable.If it is less than 30 m / sec, the spinnability is poor and it causes shots.If it exceeds 60 m / sec, the peripheral speed is too high and it is difficult to put it into practical use. It is not preferable because it becomes thinner than the above.

Next, an apparatus for producing the alumina-silica fiber precursor of the present invention will be described.

FIG. 1 is a sectional view showing an example of a rotary disc spinning apparatus used for producing the alumina-silica fiber precursor of the present invention.

In FIG. 1, an introducing pipe 2 for supplying a fiber stock solution is inserted into a hollow rotating shaft 9 of a funnel-shaped rotating disk body 1 installed in a horizontal direction, and its tip is on an inclined surface 10 of the rotating disk body 1. It is protruding. The peripheral end of the inclined surface 10 of the rotating disk body 1 is fixed to one surface of the ring-shaped nozzle plate 3 with bolts 5, and the lid 6 is fixed to the other surface of the ring-shaped nozzle plate 3 with a screw 7 to seal it. The formed intermediate space portion 11 is formed. A protrusion 12 is provided on the outer peripheral surface of the ring-shaped nozzle plate 3 on the outlet side of the spinning dope, and the protrusion 12 penetrates the spinning hole.
A plurality of projecting nozzles 4 having holes 13 are provided.

A ring-shaped nozzle plate 3 is provided outside the rotating disk body 1.
An annular body 8 having a larger diameter and having a large number of air nozzles formed on the surface thereof is installed.

FIG. 2 is a partial sectional view showing an example of the projection nozzle, and FIG. 3 is a partial sectional view showing another example. d is the inner diameter of the nozzle, D
Is the outer diameter of the nozzle, L is the length of the protrusion, and l is the depth of the spinning hole.

In the present invention, as a result of a spinning test using the above fiber stock solution, d is about 0.2 mm to about 0.4 mm, and the l / d ratio is 5 to 2
It was found that at 0 good spinning was achieved.

In this case, the wall thickness of the nozzle is preferably about 0.1 mm to about 0.5 mm, and therefore D is preferably about 0.4 mm to about 1.4 mm. Further, L is preferably at least D or more in order to prevent the spinning dope that has passed through the nozzle holes from adhering to the ring-shaped nozzle plate surface.

Further, by making L a length of at least D or more, the thickness of the ring-shaped nozzle plate is thinned by the length of L as compared with the case where the projection is not provided, so the weight of the ring-shaped nozzle plate is reduced. be able to.

Next, an example of a specific method for producing an alumina-silica fiber precursor using the apparatus shown in FIG. 1 will be described. The fiber stock solution is an inlet pipe 2 installed in the hollow rotary shaft 9 of the rotary disk body 1. Then, it is supplied to the ring-shaped nozzle plate 3 through the funnel-shaped rotating disk, and is spun through the plurality of projecting nozzles 4 by the centrifugal force due to the high speed rotation given to the rotating disk. What is spun by centrifugal force is further assisted in spinning force by hot air blown out from the air nozzle of the annular body 8 having a ring shape slightly larger than the diameter of the rotating disc installed on the outer periphery of the rotating disc. Along with partial drying, it is further dried by hot air for the purpose of collecting cotton and collected on the net surface to become an alumina-silica fiber precursor.

In FIG. 1, the ring-shaped nozzle plate 3 having a plurality of projecting nozzles 4 is fixed to the rotating disk body 1 to which power is applied by bolts 5, and thus has a disassembleable structure.

Therefore, when the protrusion nozzle 4 is serviced, since the fiber stock solution is water-soluble, the liquid pool in the nozzle portion can be easily removed by washing or immersing only the ring-shaped nozzle plate 3 with water or warm water for several minutes. The ring-shaped nozzle plate 3 which can be disassembled is further fixed to the lid 6 and the screw 7, but there is no problem even if the lid 6 and the ring-shaped nozzle plate 3 are integrated. Figure 4 (a),
FIG. 4 (b) shows the ring-shaped nozzle plate 3 having a plurality of disassembled projecting nozzle portions. FIG. 4 (a) is a sectional view and FIG. 4 (b) is a front view showing a part thereof. .

Further, as a means for forming the projection nozzle, a plurality of openings, which are considerably larger than the projection nozzle, are provided in advance in the ring-shaped nozzle plate, and a fitting member having the projection nozzle is fitted into the openings, and an adhesive is used. It can be formed by fixing with, for example.

As a concrete example, FIG. 5 is a partial explanatory view of the injection needle 14, and FIG.
The figure is an illustration of a projection nozzle formed using an injection needle. As shown in FIG. 5, a normal injection needle cut into a predetermined length to be used as a projection nozzle is used.
As shown in FIG. 6, this is fixed with an adhesive agent 15 or the like to the opening portion previously opened in the ring-shaped nozzle plate 3. In this way, for example, by using an injection needle or the like by cutting it to a predetermined length and using it, the target nozzle configuration is easier than the method of making a small-diameter hole in a thing of a predetermined thickness and manufacturing a nozzle part. This is a very effective method when it is necessary to increase the ratio of the depth to the diameter of the nozzle hole.

[Operation] In the present invention, since the fiber stock solution is spun using the projection nozzle projecting from the fiber stock solution outlet side of the ring-shaped nozzle plate provided at the peripheral end of the hollow rotating disk, the fiber stock solution and the ring-shaped solution are formed. It does not contact the nozzle plate, and the fiber concentrate is ejected from the tip of the protrusion nozzle with a small contact area.
Since the spinning is performed, the affinity with the projection nozzle is reduced, and because of the fiber stock solution at the exit of the spinning hole, there is no hemispherical lump, thread breakage, etc., and continuous and uniform operation is performed. It is presumed that a good quality alumina-silica fiber precursor with few shots can be produced.

[Examples] Next, the present invention will be described more specifically with reference to Examples.

Reference Example The shot content measurement method in alumina silica short fibers is generally difficult, and there is no standardized measurement method, but the inventors have forcibly stirred the alumina silica short fibers in water as one measurement method, A method for determining the shot content was devised by gently pouring the supernatant slurry liquid into another container, and collecting and separating the shot material deposited on the bottom of the original container through a filter paper. In the same measurement method, the slurry liquid was refined three times, and the collected shots were totaled to obtain the shot content by weight ratio. As a measurement example of the same measuring method, an example of the measurement result of the shot content in the currently marketed alumina-silica short fibers is shown below.

Arcen bulk (manufactured by Denki Kagaku Kogyo Co., Ltd., composition: Al ₂ O ₃ / SiO ₂ = 80/20) Shot content: 3-5% Suffil bulk (manufactured by ICI, composition: Al ₂ O ₃ / SiO ₂ = 95/5) Shot content: 3% Example 1 For embedding an injection needle to be used as a protruding small diameter nozzle at the peripheral edge of a rotating disk with an outer diameter of 200 mm, 48 holes with an inner diameter of 7 are opened at equal intervals. , 48 pieces of injection needles with inner diameter of 0.25 mm and outer diameter of 0.46 mm cut so that the length of the needle portion is 3 mm are fixed with adhesive for metal, and spinning device as shown in Fig. 1. Set. Next, aluminum oxychloride solution and silica sol were mixed at a ratio of Al ₂ O ₃ content of 80% by weight and SiO ₂ content of 20% by weight, and polyvinyl alcohol was added to the inorganic solid content at 7% by weight, followed by concentration operation. The viscosity at 20 ° C. was adjusted to 3,000 cp. This fiber stock solution is spun at 4,000 rpm with the above-mentioned spinning device.
When the fiber was spun at a peripheral speed of 42 m / sec, an alumina-silica fiber precursor with almost no shot was obtained. After heat-treating this precursor by an ordinary method to form alumina-silica fiber, the shot amount of the above-mentioned method was measured to be 0.3.
% By weight. Most of the fibers had a diameter of 3 to 5 μm.

Example 2 The fiber stock solution preparation and spinning operation were all carried out under the same conditions as in Example 1 except that the Al ₂ O ₃ content of the fiber stock solution was 95 wt% and the SiO ₂ content was 5 wt%. An alumina silica fiber precursor was obtained. This precursor was heat-treated by a usual method to form alumina-silica fiber, and the shot amount was measured by the above-mentioned method to find that it was 0.5% by weight. Most of the fibers had a fiber diameter of 3 to 5 μm.

Comparative Example 1 An alumina-silica fiber was obtained under the same conditions as in Example 1, except that the inner diameter of the nozzle was 0.5 mm. When the shot amount was measured by the above method, it was 3% by weight.

Comparative Example 2 An alumina-silica fiber was obtained under the same conditions as in Example 1 except that the spinning hole depth was 0.75 mm (depth 1 / inner diameter d = 3).
The shot amount measured by the above method was 5% by weight.

Comparative Example 3 The fiber stock solution was adjusted and the spinning operation was performed under the same conditions as in Example 1 except that the spinning hole depth was 6 mm (depth 1 / inner diameter d = 24). Clogged and spinning became impossible.

Comparative Example 4 Example 1 except that the fiber stock solution had a viscosity of 1000 c.p.
Alumina-silica fiber was obtained under the same conditions as above. The shot amount measured by the above method was 2% by weight.

Comparative Example 5 Example 1 except that the fiber stock solution has a viscosity of 5000 c.p.
When the fiber stock solution was adjusted and the spinning operation was performed under the same conditions as described above, the nozzle was clogged 8 hours after the start of spinning, and spinning was impossible.

[Effects of the Invention] As described above, according to the production method of the present invention, it is possible to inexpensively provide a high-quality alumina-silica fiber precursor containing almost no shots. Becomes a high-quality alumina-silica fiber through a normal heat treatment process, which impairs shot quality, such as FRM
It becomes a fiber that can be directly used for various purposes.

Moreover, since the spinning device of the present invention is provided with the protrusion nozzles in the form of protrusions, the dirt on the peripheral edge of the disk accompanied by high-speed rotation is much smaller than that of the peripheral edge directly having a small diameter opening. It is very small and very effective in preventing the occurrence of shots.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a rotary disk spinning apparatus used for producing the alumina-silica fiber precursor of the present invention, and FIGS. 2 and 3 are sectional views showing an example of a projection nozzle, respectively.
FIG. 4A is a cross-sectional view of a ring-shaped nozzle plate, FIG. 4B is a front view showing a part of the ring-shaped nozzle plate, FIG. 5 is a partial explanatory view of an injection needle, and FIG. 6 uses an injection needle. It is an explanatory view of a projection nozzle formed by. DESCRIPTION OF SYMBOLS 1 ... Rotating disk main body, 2 ... Introducing tube 3 ... Ring nozzle plate, 4 ... Projection nozzle 5 ... Bolt, 6 ... Lid part 7 ... Screw, 8 ... Annular body 9 ... Hollow rotating shaft, 10 ... Inclined surface 11 ... Medium Space portion, 12 ... Protrusion 13 ... Spinning hole, 14 ... Injection needle 15 ... Adhesive, d ... Inner diameter of nozzle l ... Depth of spinning hole, D ... Outer diameter of nozzle L ... Length of protrusion

Claims (1)

[Claims] 1. A method for producing a high-quality alumina-silica fiber precursor containing almost no non-fibrous material from a fiber stock solution comprising a mixed solution of an aluminum compound aqueous solution containing an organic polymer and a silica compound, wherein a viscosity of 1500 to 3500c is obtained. .
The fiber stock solution of p. is spun using a plurality of nozzles having an inner diameter of 0.2 to 0.4 mm and a spinning hole depth to inner diameter ratio of 5 to 20 provided at the peripheral end of a hollow rotating disk. A method for producing an alumina-silica fiber precursor.