JPH0478736B2 - - Google Patents

Description

[Detailed description of the invention]

₍ Industrial _{Application Field} ) _The present invention relates to a compound ( The present invention relates to a method for producing fibers or membranes of barium titanogallate). (Prior art) A compound (barium titanogallate) having a tetragonal tunnel structure represented by the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ (x = 0.2 to 1.0) has excellent heat resistance and heat insulation properties. Because of its excellent properties, it is useful as a heat-resistant and heat-insulating material, and is also used as a reinforcing material for plastics, metals, ceramics, etc. Conventionally, as a method for producing this type of compound, the flux method is known in the case of compounds that use an alkali metal instead of Ba (Japanese Patent Application No. 1983-1999).
124095). This method uses alkali molybdate as a flux, melts it at high temperature, and then slowly cools it to grow a fibrous single crystal through a dissolution-precipitation reaction. However, the compound represented by Ba in the above general formula (barium titanogallate) cannot be grown using this method because there is no suitable flux. On the other hand, as methods for producing polycrystalline fibers for inorganic fibers such as alumina fibers and zirconia fibers, methods such as a precursor polymer method, a slurry method, an inorganic salt method, and a sol method have been known, and it is difficult to apply them to the production of the above compounds. can also be considered. First, representative examples of these methods are as follows. The precursor polymer method is

In this method, ertel silicate is mixed into a viscous solution containing polyaluminoxane, an inorganic polymer having a main chain consisting of [Formula] (Y is, for example, an ethyl group or an ethoxy group), dry spinning, and firing. The slurry method _{uses Al2O3} fine powder and a small amount of _MgCl2 .
Al ₂ (OH) ₅ Cl・ as a binder component in 6H ₂ O
In this method, 2.2H ₂ O is added to form a viscous slurry, which is then dry spun and fired. The inorganic salt method is a method in which a water-soluble organic polymer such as polyethylene oxide or PVA is added to an aqueous solution of aluminum salt, and water-soluble polysiloxane is further mixed to form a viscous liquid, which is then blown out from a nozzle and fired. The sol method is a method in which silica sol and boric acid are added to alumina sol containing ions such as HCOO and CH ₃ COO to form a viscous liquid, which is then spun and fired. (Problems to be Solved by the Invention) However, when the flux method and the method for producing polycrystalline fibers are applied to the production of a compound having the above general formula (barium titanogallate), the following problems arise. There is a point. First, the flux method has the problem that not only is it impossible to obtain long fibers, but also that expensive flux is used, requiring a recovery process, which increases manufacturing costs. On the other hand, in the case of manufacturing polycrystalline fibers, the spinning solution is used to spin fibers, so the spinning stock solution is important, and the physical properties of the solution such as viscosity, spinnability, uniformity, and stability are important. In addition to being an important factor, it is also important that the spinning stock solution is easy to produce and has excellent spinnability. From this point of view, when applying the above-mentioned various methods, firstly, although the precursor polymer method has high uniformity, it is difficult to control the manufacturing process for producing the spinning dope. In the sol-gel method, it is difficult to control the concentration because precipitation and turbidity occur during the concentration stage, and the viscosity increases rapidly. Since the inorganic salt method uses a water-soluble organic polymer to provide the viscosity that gives the fiber form, the stock solution may lack stability, such as gelation during the preparation stage. In addition, the slurry method is a so-called heterogeneous system, and the viscosity, amount added, and dispersion state of the solid particles constituting the spinning stock solution subtly affect spinnability, making it difficult to control. The present invention is based on the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆
Compound (barium titanogallate) having a tetragonal tunnel structure represented by (x = 0.2 to 1.0)
When producing fibers or membrane-like products, it solves the problems of the spinning dope in conventional methods, makes it easy to adjust the viscosity of the spinning dope, and has excellent spinnability, uniformity, and stability. The object of the present invention is to provide a method that has good properties and is easy to manufacture. (Means for Solving the Problem) In order to achieve the above object, the present inventors
We focused on the advantage of applying the manufacturing method of polycrystalline fibers rather than the flux method, which uses expensive flux, and as a result of intensive research to solve the unique problems, we developed a specific material as a composition raw material. It was discovered that a viscous liquid suitable for spinning can be obtained by adding it to a specific organic acid aqueous solution at a predetermined ratio, dissolving and concentrating it, and that the desired purpose can be achieved by extruding, molding, and baking this liquid. , completed the present invention. That is, the general formula Ba _x Ga _16+2x according to the present invention
In short, the method for producing fibers or membranes of the compound represented by Ti _16-2x O ₅₆ (barium titanogallate) uses a titanium alkoxide as the Ti component of the raw materials, a nitrate of the component as the Ga component, Using the carbonate of the component as the Ba component, each raw material blended in the composition ratio shown by the above general formula is added to the Ba component,
Add to an aqueous solution of single or mixed organic acids such as citric acid and tartaric acid in a molar amount or more of 0.85 times the total amount of Ti component and Ga component, dissolve and concentrate to obtain a spinning solution, and then spin this to form a fiber or film. _Ba
Formations consisting of a single phase of Ga _16+2x Ti _16-2x O ₅₆ can be obtained, or Ba _x Ga _16+2x Ti _16-2x O ₅₆ is the main formed phase and Ga ₂ TiO ₅ phase, β−Ga ₂ O ₃
This method is characterized by obtaining a two-phase, three-phase, or four-phase mixed molded product in which a small amount of (β-gallium) and an unknown phase are formed. The present invention will be explained in detail below. (Function) First, as a raw material for producing a compound (barium titanogallate) having a composition represented by the above-mentioned general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ and having a tetragonal tunnel structure, the following specific ingredients are used. Use raw materials. Titanium alkoxide is used as the Ti component. As this titanium alkoxide, for example,
Examples include titanium tetraisopropoxide and titanium tetra-normal butoxide. Incidentally, titanium alkoxide reacts very easily with citric acid and tartaric acid to obtain a transparent and uniform solution, which can be converted into an oxide by firing. As the Ga component, its nitrate is used because of its availability and ease of handling. Even if the nitrate is added as a Ga component to the transparent solution thus obtained, the solution will not become non-uniform. In addition, Ga〓 may form a solid solution with Fe, Cr, and Al.
In this case, appropriate organic salts, inorganic salts, and alkoxides thereof can be used as raw materials. In addition, its carbonate is used as the Ba component, but
When mixed with an organic acid aqueous solution (described later), it releases CO ₂ and becomes a transparent homogeneous solution. Each of these raw materials is added to a single or mixed aqueous organic acid solution of citric acid and tartaric acid in a composition ratio according to the above general formula, and is dissolved and concentrated to form a viscous liquid with stringiness. In this case, the amount of the single or mixed organic acids of citric acid and tartaric acid needs to be 0.85 times or more of the total number of moles of the Ba component, Ti component, and Ga component. If the amount is less than 0.85 times the mole, the resulting spinning stock solution will become non-uniform, will not exhibit spinnability, and will be difficult to solidify.
Cannot form into fibrous or film-like materials. It is preferable to use water in an amount of 20 to 50 times the total number of moles of the Ba component, Ti component, and Ga component in the aqueous solution of the organic acid. This will give you a clear and homogeneous solution.
When this is heated and concentrated to a viscosity of about 1 to 100 poise, a viscous liquid that is stringable at 90 to 100°C is obtained. This liquid solidifies as the temperature decreases. Therefore, it is preferable to perform the spinning at 90 to 100°C. When spinning, a long fiber is obtained using a nozzle, and a film-like material is obtained when extruded through a slit.
Moreover, it can be made into ultra-fine short fibers by extruding it through a thick diameter nozzle and burning and blowing it away with flame. In addition, when the range of x in the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ is 0.2≦x≦1.0, there is not much difference in the spinnability seen in the spinnability, viscosity, etc. of the spinning dope. unacceptable. The obtained fibrous or film-like material is subjected to water removal,
After heating in air at 700 to 1000℃ to decompose and remove organic substances, baking at 1200 to 1600℃ yields the desired compound (fiber or film-like material) having a tetragonal tunnel structure. It will be done. However, 1200℃
If it is less than 1600°C, sintering will not be completed, and if it exceeds 1600°C, it will start to melt, which is not preferable. In addition, in the above general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ , when x = 0.6 and 1350°C, the generated phase obtained by firing is a single phase or a trace of only a compound having a tetragonal tunnel structure. Ga ₂ TiO ₅ phase, β−
It becomes a mixed phase with Ga ₂ O ₃ phase, but as x becomes smaller than 0.6, unknown phase (3.29 Å, 3.15
Å, 2.48 Å, 2.22 Å, and 2.18 Å), and as x becomes larger than 0.6, β-Ga ₂ O ₃ (β- Gallia) phase, Ga ₂ TiO ₅
and the number of unknown phases increases. The optimal composition range of x is 0.5
<x≦0.65, but even when x is in the range 0.2≦x≦1.0 shown in the above general formula, the basic physical properties for its use are hardly affected. (Example) Next, an example of the present invention will be shown. Example 1 This example is an example in which x=0.6 in the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ and in which citric acid is used as the organic acid. First, add 21.0 g of titanium tetraisopropoxide to a solution of 28.6 g of citric acid dissolved in 50 ml of distilled water.
was added dropwise and stirred for about half a day to obtain a transparent solution. Next, 0.59 g of barium carbonate was gradually added to this solution and stirred until the solution became transparent and uniform. All the above operations were performed at room temperature. In addition, gallium nitrate nonahydrate (Ga
After adding 35.9 g of (NO ₃ ) ₃ ·9H ₂ O) and stirring at room temperature for a while, the mixture was heated at 100° C. and concentrated until the viscosity reached 100 poise. This was a transparent, uniform, viscous solution, and when it was allowed to cool, its viscosity gradually increased and it had good stringability. Next, the material in an appropriate viscous state is extruded through a nozzle into a dry atmosphere at room temperature to form a material with a diameter of 5 to 100 μm.
m long fibers were obtained. This fiber was colorless and transparent. The obtained fibers were dried at 100°C overnight and then heated to 900°C.
The mixture was heat-treated at 1350°C for 2 hours, and then fired at 1350°C for 30 hours. The obtained fiber contains a single phase of barium gallotitanogallate with a tetragonal tunnel structure of composition Ba _0.6 Ga _17.2 Ti _14.8 O ₅₆ and traces of Ga ₂ TiO ₅
The fibers were composed of a mixed phase with a β-Ga 2 O phase and a β-Ga ₂ O ₃ phase. Example 2 This example is an example in which x=0.5 in the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ and synthesis using tartaric acid as the organic acid. First, 14.2 g of titanium tetraisopropoxide was added dropwise to a solution of 16.3 g of tartaric acid dissolved in 30 ml of distilled water, and a transparent solution was obtained by stirring for about half a day. Next, 0.33 g of barium carbonate was gradually added to this solution, and the solution was stirred until it became transparent and uniform. All the above operations were performed at room temperature. In addition, gallium nitrate nonahydrate (Ga
After adding 23.7 g of (NO ₃ ) ₃ ·9H ₂ O) and stirring at room temperature for a while, the mixture was heated at 100° C. and concentrated until the viscosity reached 100 poise. This was a transparent and uniform viscous solution, and when it was left to cool, the viscosity gradually increased and it had good stringability. Next, the material in an appropriate viscous state is extruded through a nozzle into a dry atmosphere at room temperature to form a material with a diameter of 5 to 100 μm.
m long fibers were obtained. This fiber was colorless and transparent. The obtained fibers were dried at 100°C overnight and then heated to 900°C.
The mixture was heat-treated at 1350°C for 2 hours, and then fired at 1350°C for 40 hours. The obtained fibers were composed of a mixed phase of gallotitanogallate having a tetragonal tunnel structure with a composition of Ba _0.5 Ga ₁₇ Ti ₁₅ O ₅₆ and a small amount of an unknown phase. Example 3 This example is an example in which x=0.7 in the general formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ , and in which citric acid is used as the organic acid. First, add 14.2 g of titanium tetraisopropoxide to a solution of 23.5 g of citric acid dissolved in 50 ml of distilled water.
was added dropwise and stirred for about half a day to obtain a transparent solution. Next, 0.47 g of barium carbonate was gradually added to this solution and stirred until the solution became transparent and uniform. All the above operations were performed at room temperature. In addition, gallium nitrate nonahydrate (Ga
After adding 24.9 g of (NO ₃ ) ₃ ·9H ₂ O) and stirring at room temperature for a while, the mixture was heated at 100° C. and concentrated until the viscosity reached 100 poise. This was a transparent, uniform, viscous solution, and when it was allowed to cool, its viscosity gradually increased and it had good stringability. Next, the material in an appropriate viscous state is extruded through a nozzle into a dry atmosphere at room temperature to form a material with a diameter of 5 to 100 μm.
m long fibers were obtained. This fiber was colorless and transparent. The obtained fibers were dried at 100°C overnight and then heated to 900°C.
The mixture was heated at 1350° C. for 2 hours, and then heated at 1350° C. for 50 hours. The obtained fibers contain gallotitanogallate having a tetragonal tunnel structure with a composition of Ba _0.7 Ga _17.4 Ti _14.6 O ₅₆ and some amounts of β-Ga ₂ O ₃ (β-gallia) phase and Ga ₂ TiO The fiber consisted of a mixed phase of 5 and ₅ . (Effects of the Invention) As detailed above, according to the present invention, when producing fibers or membranes of the compound (barium titanogallate) having a tetragonal tunnel structure represented by the general formula, spinning It is easy to adjust the viscosity of the stock solution to an appropriate value, and it has excellent spinnability, uniformity, and stability, good spinnability, and is easy to manufacture. Therefore, it has the excellent effect that fibers or membranes having the desired composition can be obtained more easily and at lower cost.

Claims (1)

[Claims] 1 General formula Ba _x Ga _16+2x Ti _16-2x O ₅₆ (However, x=0.2
~1.0) When producing a compound having a tetragonal tunnel structure, a titanium alkoxide is used as the Ti component of the raw materials, a nitrate of the component is used as the Ga component, and a carbon salt of the component is used as the Ba component. Aqueous solutions of single or mixed organic acids of citric acid and tartaric acid in a molar amount or more of 0.85 times or more based on the total amount of the Ba component, Ti component, and Ga component are prepared using the following methods: In addition, _Bax Ga _16+2x Ti _16-2x O _{56Ba x} Ga _16+2x characterized by obtaining a formation consisting of a single phase
A method for producing a fiber or film-like product of barium titanogallate represented by Ti _16-2x O ₅₆ . 2 The phase generated by the firing is Ba _x Ga _16+2x
Ti _16-2x O ₅₆ is the main phase, and other
Claim 1: It is a mixed system in which a small amount of Ga ₂ TiO ₅ phases, β-Ga ₂ O ₃ (β-Galia), and an unknown phase are formed.
The method described in.