KR910000294B1 - Process for synthesis of alumina-gol - Google Patents

Abstract

The solution which comprises 1 mol aluminum 2-but oxide or aluminam iso-propoxide and 3-10 mol alcohol is added to 0.4-1.5 acetyl acetone. The above mixed solution is hydrolyzed with 0.25-1.25 mol water. Then 0.0005-1.3 mol conc. acid is added to the hydrolyzed mixture, thus making it possible to synthesize polymerized alumina sol in non-aqeous solution. The synthesized alumina sol is dried at 80-90 deg. C When the viscosity of the sol reaches at 105-10wCPS, it if fed into spinneret, then spun as a multi-crystalline alumina inorganic fiber.

Description

Synthesis method of polymerized alumina sol in non-aqueous solution and preparation method of alumina polycrystalline inorganic fiber using same

Figure 1 is a graph showing the viscosity over time of the polymerized alumina sol obtained by adding the amount of acetin acetone (0.1 mol. 0.5 mol, 1.5 mol).

2 is an FT-IR spectra of the polymerized alumina sol obtained by the method of the present invention.

3 is an FT-IR spectra of alumina sol obtained by a conventional method.

4 is a cross-sectional view of the present invention fabric manufacturing apparatus.

5 is an X-ray diffraction partial rate according to the present invention inorganic fiber and heat treatment temperature.

6 is an electron micrograph after firing of the inorganic fiber of the present invention (a) is 524 times, (b) is 1350 times enlarged picture.

The present invention relates to a method for synthesizing a highly viscous alumina sol in a polymerized state from a non-aqueous solution and a method for producing an inorganic fiber using the same.

Such aluminazole has higher viscosity and superior radioactivity than conventional colloidal alumina sol made from aqueous solution, and is superior to conventional colloidal sol as a raw material for coating and binder as well as preparing alumina inorganic fibers.

The alumina sol according to the conventional method has a very low viscosity as a colloidal state and could not obtain viscosity and workability suitable for spinning without the addition of water-soluble high molecular water such as polyethylene oxide. However, the alumina sol according to the present invention has a very high viscosity of the sol itself structurally than the colloidal since the precursor is contained in a chain form rather than a spherical form.

In the present invention, the aluminum alkoxide is hydrolyzed, but the amount of water is limited to less than the theoretical water content so that only a part of the alcohol group around the aluminum atom is partially hydrated to form a precursor in a chain state. To maintain partial hydration to the end, a portion of the alcohol group around Al was capped using acetylacetone, which forms a stable compound bond. I was.

In addition, the reaction and concentration were maintained below the volatilization point of acetylacetone. The main use of this alumina sol is to make inorganic fibers, and it can be used for composite materials, coatings and binders.

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

In the present invention, aluminum alkoxide is used as a starting material to dissolve it in alcohol and reacts with acetylacetone, which causes a stable chemical bond at first, followed by hydrolysis by addition of water, followed by polymerization with acid to add a stable polymerization sol. The first reaction with acetylacetone to form is as follows.

In the above, AA is acetylacetone (CH ₃ COCH ₂ COCH ₃ ), R is secondary-butyl group or iso-propyl group.

The aluminum alkoxides used in the present invention are aluminum secondary-butoxide or aluminum iso-propoxide and they all form a clear sol. The alcohol is suitably used because 1-propanol, 2-butanol, and the like can form a clear sol for each alkoxide. The amount of alcohol does not matter, but there is a problem of separation later, and if it is small, precipitation occurs, so the amount of 1-propanol is suitably 3-6 mol to 1 mol of aluminum secondary-butoxide, and 1 mol of aluminum iso-propoxide. A suitable amount of iso-protanol was 7-10 mol relative to. The amount of acetylacetone is also an important factor. The maximum amount is 1.5 moles with respect to 1 mole of alkoxide, and when more is added, complexes of aluminum acetylacetonate are formed by the following reaction to form precipitates.

When water is added to the transparent sol where acetylacetonation has occurred, a hydrolysis reaction occurs.

In this reaction, too, the reaction varies depending on the amount of water. When the amount of water is large, rapid gelation occurs, making it difficult to form a transparent sol, and even when the amount of water is small, the rapid gelation is also undesirable. Therefore, the amount of water is preferably 0.25-1.25 moles per 1 mole of alkoxide.

The hydrolyzed solution is added with acid to form a polymer sol. The reaction is as follows.

The reaction of 1) is an ideal polymerization reaction, and the reaction of 2) is a reaction in which unreacted materials that do not undergo hydrolysis are polymerized. OR in 1) may react with water to form an OH bond and generate ROH. At this time, the acid added as a catalyst is suitable for strong acid. If the amount of acid is excessive, rapid gelation occurs, and if the acid is small or small, the polymerization reaction occurs, but the rate decreases. That is, acid acts as a catalyst, which accelerates the reaction. The amount of acid is suitably up to 1.5 moles for hydrochloric acid per mole of alkoxide. Thereafter, the alumina polymerization sol is formed by the condensation reaction.

Thus after the formation of the sol is dried when the dryer to 80-90 ℃ 100 sigan PH so as 7.8 13.3 viscosity is changed to 10 ⁸ cps from 10cps to 10 ⁵ -10 ⁷ cps when the fourth-degree fiber production apparatus suitable for spinning To prepare inorganic fibers.

4 is a schematic configuration diagram of a textile manufacturing apparatus of the present invention using a centrifugal separation method.

The apparatus of the present invention includes a body (1), a pressurizing device (2) installed on top of the body, a cylinder body (3) condensed inside the body and a rotating device (4) for rotating the cylinder body. And a heater 5 and a sol storage tank 14 for heating the cylinder body.

The body 1 has a space inside. The ring pressurization device 2 was operated by an external pressure means (not shown) to cause the sol 6 in the sol storage tank 14 to fall on the cylinder body 3 to be described later at a constant speed.

The cylinder body 3 is perforated with holes 7 at regular intervals on the outer circumference, and is adhered to the rotary shaft 11 and is driven by the rotary shaft and the belt 8 by the power of the motor 9 and the reducer 10. This was to be delivered.

The heater 5 is provided adjacent to the cylinder 3, and the heater 12 of the heater is configured to be adjacent to the bottom of the cylinder to be heated to a constant temperature.

Such a device of the present invention is rotated at a constant speed by the cylinder body 3 and the rotary device 4 inside the body 1.

In the above state, the cylinder body is heated and maintained at a constant temperature by the heater 5, and the pressurizing device 2 is operated by an external pressure means so that the sol 6 in the sol-jojo major 14 moves at a constant speed. Falls on (3)

The sol 6 dropped to the cylinder body is spun through the through hole 7 formed in the cylinder body by the centrifugal force of the cylinder body, and the short fibers 13 are continuously manufactured.

Example 1

4 mol of iso-propanol ((CH ₃ ) ₂ CHOH) was added to the three-necked flask at room temperature, and then 1 mol of aluminum di-butoxide (Al (OC ₄ H ₉ ) ₃ ) was slowly dropped over 6-7 minutes. When dropped, it becomes a translucent solution. When 0.5 mol of acetylacetone was dropped through the pipette while stirring with a stirrer, the solution produced a transparent sol. The mixture was stirred for at least 2 hours so that the acetylacetonation reaction could sufficiently occur, and then 1 mol of water was added thereto. When water is added, the color of the sol becomes lighter, but the transparent sol remains intact. The mixture was stirred for 1 hour for sufficient hydrolysis, after which 0.0015 mol of hydrochloric acid was added, the solution was again dried at 80 ° C. in a drier, and the pH and viscosity were measured according to the drying time.

TABLE 1

TABLE 2

The above sol was dried and calcined at 1100 ° C. or higher to find that all of the sol was transferred to α-Al ₂ O ₃ .

Experimental Example

The viscosity change with time of the alumina sol obtained by installing in Example 1 except having changed the addition amount of acetylacetone into 1.5 mol and 0.1 mol was the same as FIG.

As shown in FIG. 1, when the amount of acetylacetone added was 1.5 mol or 0.1 mol, the viscosity did not exceed 10 ² cps even after 100 hours of drying time, but when 0.5 mol was used as in Example 1, the viscosity after 100 hours was 10 ^{It was found that} more than ⁸ it was possible to obtain aluminimazole having excellent radioactivity.

In addition, the alumina sol prepared by the method of Example 1 of the present invention was analyzed by FT-IR as shown in FIG. 2, and the alumina sol prepared by the conventional aqueous solution by FT-IR was analyzed by the third result. The alumina sol prepared according to the present invention is different from the alumina sol prepared by the conventional method due to the fact that the second and the third degrees are different from each other.

As apparent from Table 2, the alumina sol prepared according to the present invention is a polymerizable sol, which can adjust the viscosity according to drying time without adding an additive, and thus can produce high purity alumina fibers. Can be used as

Example 2

The alumina sol synthesized according to Example 1 was dried at 80 ° C. for 97 hours, and when the viscosity reached 10 ⁶ cps, the alumina sol was placed in the sol storage tank 14 of FIG. 4, and then the cylinder body 3 inside the body 1 was rotated. 4), pressurizing the device while rotating to 3000RPM by heating to 450 ° C. with the heater 5 and dropping the sol 6 in the sol storage tank 14 into the cylinder body 3 at 5 ml / sec. The sol dropped to the yarn is spun through a through hole 7 having a diameter of 495 mu formed in the cylinder body, thereby producing short fibers 13.

As a result of heat-treating the short fibers thus prepared, as shown in X-ray diffraction analysis of FIG. 5, the amorphous fiber was amorphous below 900 ° C, γ-Al ₂ O ₃ began to appear at 900 ° C, and δ-Al ₂ O at 950 ° C. Partially transitioned to ₃ , α-A1 ₂ O ₃ and θ-Al ₂ O ₃ appeared at 1000 ℃, α-Al ₂ O ₃ was the main phase above 1050 ℃.

In addition, when the prepared short fiber was fired, the average particle diameter of the fiber was about 70 μm and the fiber was polycrystalline alumina as shown in FIG.

Claims (2)

After dissolving 1 mol of aluminum secondary-butoxide or aluminum iso-propoxide in 3-10 mol of alcohol, 0.4-1.5 mol of acetylacetone was added for reaction, followed by hydrolysis with 0.25-1.25 mol of water, followed by strong acid 0.0005-1.3 A mole is added to the method for synthesizing the polymerized alumina sol in a non-aqueous solution. Method for producing alumina polycrystalline inorganic fiber which is alumina sol synthesized by the method of claim 1 is dried at 80-90 ℃ and spun with a spinning machine when the viscosity is 10 ⁵ -10 _w cps.

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