JPH0333219A - Method for producing barium titanogallate fibers or membranes - Google Patents

Abstract

PURPOSE:To obtain fiber or film of the subject compound having a tetragonal tunnel structure by compounding raw materials of Ti, Ba and Ga components at ratios corresponding to the final composition, dissolving the mixture in an aqueous solution of citric acid or tartaric acid, concentrating the solution and spinning the obtained dope. CONSTITUTION:A spinning dope is produced by using (A) a titanium alkoxide as a Ti component, (B) Ga nitrate as a Ga component and (C) Ba carbonate as a Ba component, compounding the above components at ratios of formula (x is 0.2-1.0), adding the mixture to (D) an aqueous solution of >=0.85mol (based on 1mol of A+B+C) of organic acids consisting of citric acid and/or tartaric acid, dissolving the mixture and concentrating the obtained solution. A green fiber or film formed by spinning the dope is converted to an object fiber or film consisting of a single phase expressed by the formula.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has a tetragonal tunnel structure and has a general formula B a
XGal, +2xTiiG-2) (09, (however, x=
The present invention relates to a method for producing fibers or membranes of a compound (barium titanogallate) having a composition represented by 0.2 to 1.0).

(Prior art) General formula B a X G a 16 + 2 XT]
, z G −2X O56 (X = Q, 2~1.O
) has a tetragonal tunnel structure (barium titanogallate), which has excellent heat resistance and heat insulation properties, and is therefore useful as a heat-resistant and heat-insulating material, and is also used as a reinforcing material for plastics, metals, ceramics, etc. It will be done.

Conventionally, as a method for producing this type of compound, a flux method is known in the case of a compound using an alkali metal instead of Ba (Japanese Patent Application No. 61-124095). In this method, alkali molybdate is used as a flux and melted at high temperature, then slowly cooled, and a fibrous single crystal is grown through a dissolution-precipitation reaction.

However, the compound represented by Ba in the above general formula (barium titanogallate) cannot be grown by this method because there is no suitable flux.

On the other hand, conventional methods for producing polycrystalline fibers such as alumina fibers and zirconia fibers include the pre-drunken polymer method,
A slurry method, an inorganic salt method, a sol method, etc. are known, and may be applied to the production of the above-mentioned compounds. First, representative examples of these methods are as follows.

The Maeho polymer method involves dry spinning by mixing ertel silicate into a viscous solution containing polyaluminoxane, an inorganic polymer having a main chain consisting of -AQ-0- (Y is, for example, an ethyl group or an ethoxy group). This is a method of firing.

Slurry method is Al1,0. Fine powder and small amounts of M g CQ
26H, O, binder component L, TE A Q, (OH
) Add 5CQ, 2.2H and O to make a viscous slurry,
This is a method of dry spinning and firing.

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 an aluminum salt, and water-soluble polysiloxane is further mixed to form a viscous liquid, which is blown out from a nozzle and then fired.

In the sol method, silica sol and phosphoric acid are added to alumina sol containing ions such as HCOO, CH, and Coo to form a viscous liquid.
This method involves spinning and firing the fibers.

(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, with the flux method, not only is it impossible to obtain long fibers, but also expensive flux is used.
There is a problem in that a recovery process is required, 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 the various methods described above are applied, firstly, although the pre-polymer method has high uniformity, it is difficult to control the manufacturing process for producing the spinning dope. Sol-
In the gel method, during the concentration stage, precipitation and turbidity occur, and the viscosity increases rapidly, making it difficult to control the concentration. The inorganic salt method uses a water-soluble organic polymer to provide the viscosity that gives the fiber shape, so! The stock solution may lack stability, such as gelation at step 111. Also,
The slurry method is a so-called heterogeneous system, and there are problems such as the viscosity of the solid particles constituting the spinning stock solution, the amount of addition, the dispersion state, etc., which subtly affect the spinnability, making it difficult to control.

The present invention provides the general formula B axGatg+z)(Tlz
Problems with the spinning stock solution in the conventional method when producing fibers or membranes of a compound (barium titanogallate) having a tetragonal tunnel structure represented by 6-zxO□ (x = 0.2 to 1.0) The purpose of the present invention is to provide a method that can easily adjust the viscosity of the spinning stock solution, has excellent spinnability, uniformity, and stability, has good spinnability, and is easy to manufacture. It is something to do.

(Means for Solving the Problems) The present inventors have found that in order to achieve the above object, it is advantageous to apply a method for producing polycrystalline fibers instead of a flux method that uses expensive flux. As a result of intensive research to solve unique problems, we developed a viscosity suitable for spinning by using a specific material as a composition raw material, adding it to a specific organic acid aqueous solution at a predetermined ratio, dissolving and concentrating it. They discovered that the desired purpose could be achieved by extruding, molding, and baking a liquid obtained, and completed the present invention.

That is, the general 2 BaxOax6+zXT according to the present invention
In short, the method for producing fibers or membranes of the compound (barium titanogallate) represented by il&-2XO□ is to use titanium alkoxide as the raw material Ti component, use the nitrate of the Ga component as the raw material, and use the Ba component as the raw material. Using the carbonate of the component, each raw material blended in the composition ratio shown by the above general formula was added with citric acid and By adding it to an aqueous solution of tartaric acid alone or a mixed organic acid, dissolving and concentrating it to obtain a spinning solution, then spinning this to form a fibrous or membrane-like product, and then baking it at 1200 to 1600 ° C.
Ba) (Ga1G,XTi,!-2xO,, a formation consisting of a single phase can be obtained, or Ba
zxT il, -2xo□ is the main produced phase, and Ga.

This method is characterized by obtaining a two-, three-, or four-phase mixed molded product in which a small amount of Tie, β-Ga, O, (β-Galia), and unknown substances are produced.

The present invention will be explained in detail below.

(Function) First, the general formula BaxGa+s+*xTlns-z
) (As raw materials for producing a compound (barium titanogallate) having a composition represented by Oss and having a tetragonal tunnel structure, the following specific component materials are used.

Titanium alkoxide is used as the Ti component. Examples of the titanium alkoxide include titanium tetraisopropoxide and titanium tetra-normal butoxide. In addition, titanium alkoxide is citric acid,
It reacts very easily with tartaric acid, giving a clear homogeneous solution, which can be converted into an oxide by calcination.

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.

Further, Ga may be dissolved in solid form with Fe, Cr, and A(I).

In this case, appropriate organic salts, inorganic salts, and alkoxides of these can be used as raw materials.Also, carbonates of Ba components are used, but when mixed with an organic acid aqueous solution (described later), they release CO2. The solution becomes clear and homogeneous.

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, will be difficult to solidify, and will not be able to form into a fibrous or film-like product. 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.

As a result, a transparent homogeneous solution is obtained, and when this is heated and concentrated to a viscosity of about 1 to 100 voids,
A viscous liquid with stringiness is obtained at ~100°C. This liquid solidifies as the temperature decreases. Therefore, it is preferable to perform the spinning at 90 to 10'O<0>C.

During spinning, long fibers are obtained by using a nozzle, and a membrane-like material is obtained by extruding from 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.

Note that the general formula BaxGa,! +2XTi16-2x
When the range of X in O, G is 0.2≦X≦1.0, there is not much difference in the spinnability, viscosity, etc. of the spinning dope.

The obtained fibrous or film-like material is heated to a temperature of 700 to
After heating in air at 1000°C to decompose and remove organic substances, baking at 1200-1600'C yields the desired compound (fiber or film-like material) having a tetragonal tunnel structure. .

However, sintering will not be completed below 1200℃, and
If the temperature exceeds 0°C, it will start to melt, which is not preferable.

Note that the general formula B axGaxi4zxTltc-z
When x = 0.6.1350°C in x○sG, the generated phase after firing is a single phase consisting only of compounds that form a tetragonal tunnel structure, or a trace of Ga2TiOs.
Phase, β-Ga20. It will be a mixed phase with the phase, but if X is 0.6
The smaller the size, the more unknown compounds (3, 29, 3.
■The larger the number of lattice spacings of 5, 2.48, 2.22, and 2.18, and the larger X is greater than 0.6, the more compounds other than those having a tetragonal tunnel structure in the formed phase. β-Ga, ○, (β-Galia) phase, Ga, Ti
O, and the number of unknown uses increases. The optimal composition range of X is 0,
5<x≦0.65, but even when the range of

(Example) Next, examples of the present invention will be shown.

One example of this is the general formula B a) (Ga□, +2) (Til
G-2XO,.

This is an example in which x=0.6 and synthesis using citric acid as the organic acid.

First, 21.0 g of titanium tetraisopropoxide was added to a solution of 28.6 g of citric acid dissolved in 50+nQ of distilled water.
A clear solution was obtained by lowering ga-W and stirring for about half a day.

Next, 0.59 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.

To this, 35.9 g of gallium nitrate nonahydrate (Ga(No, ), -9H20) was added,
After stirring at room temperature for a while, the mixture was heated at 100° C. and concentrated until the viscosity reached 100 poise. This solution was a transparent, uniform, and viscous solution, and when it was left to cool, its viscosity gradually increased and it had good stringability.

Next, the material in an appropriate viscous state was extruded through a nozzle into a dry atmosphere at room temperature to obtain long fibers with a diameter of 5 to 100 μm. This fiber was colorless and transparent.

The obtained fibers were dried at 100°C overnight, then heat treated at 900°C for 2 hours, and then fired at 1350°C for 30 hours.

The obtained fibers were B ao + & G ant 42
A single phase of barium gallotitanogallate with a tetragonal tunnel structure of composition T 114 os Osb and trace amounts of Ga.

The fiber consisted of a mixed phase of Tie phase and β-Ga2oJ phase.

Blunder fi2 In this example, the general formula B a xG a 1B +Z
In T 111-x OS &, x=0.5, and this is an example of 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 mQ 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 (G a (N O3) 3.9 Ha O) 23
, 7 g, stirred at room temperature for a while, and then heated to 100°C.
The mixture was heated and concentrated until the viscosity reached 100 poise.

This was a transparent and uniform viscous solution, and when it was allowed to cool, the viscosity gradually increased and it had good spinnability.

Next, the material in an appropriate viscous state was extruded through a nozzle into a dry atmosphere at room temperature to obtain long fibers with a diameter of 5 to 100 microns. This fiber was colorless and transparent.

The obtained fibers were dried at 100°C overnight, then heat treated at 900°C for 2 hours, and then fired at 1350°C for 40 hours.

The obtained fiber was a fiber composed of a mixed phase of gallotitanogallate having a tetragonal tunnel structure with a composition of Ba, sGa, iTi, and 50sb, and a small amount of an unknown substance.

A running example of BaXGa1 is the general formula BaXGa1. ．． xTi1G-, xO
, , this is the case where x=0.7, and this is an example of synthesis using citric acid as the organic acid.

First, 4.2 g of titanium tetraisopropoxide was added to a solution of 23.5 g of citric acid dissolved in 50 g 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 the mixture was stirred until it became transparent and uniform. All the above operations were performed at room temperature.

To this, 24.9 g of gallium nitrate nonahydrate (Ga(No3L"9H20)) was added, stirred for a while at room temperature, and then heated at 100°C until the viscosity reached 1.
It was concentrated to 0.00 voids. This was a transparent, uniformly viscous solution, and when it was allowed to cool, the viscosity gradually increased and it had good stringability.

Next, the material in an appropriate viscous state was extruded through a nozzle into a dry atmosphere at room temperature to obtain long fibers with a diameter of 5 to 100 μm. This fiber was colorless and transparent.

The obtained fibers were dried at 100°C overnight, then heat-treated at 900°C for 2 hours, and then at 1350°C for 50 hours.

The obtained fiber is B a@, 7Ga17□T1z<, so
It was a fiber consisting of a mixed phase of gallotitanogallate having a tetragonal tunnel structure with a composition of As described in detail above, according to the present invention, when producing fibers or membranes of the compound (barium titanogallate) having a tetragonal tunnel structure represented by the above general formula, the spinning stock solution It is easy to adjust the viscosity 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 (2)

[Claims] (1) General formula Ba_x Ga_16_+_2xTi_1
When producing a compound having a tetragonal tunnel structure represented by 6_-_2xO_56 (x: 0.2 to 1.0), titanium alkoxide was used as the Ti component of the raw material,
Using the nitrate of the component for the Ga component and the carbonate of the component for the Ba component, each raw material is blended in the composition ratio shown by the above general formula, and the total amount of the Ba component, Ti component, and Ga component is It was added to an aqueous solution of single or mixed organic acids of citric acid and tartaric acid in a molar amount or more of 0.85 times or more, dissolved and concentrated to obtain a spinning solution, which was then spun to form a fibrous or membrane-like product. After that, by firing at 1200 to 1600°C, Ba_xGa_16_+_2xTi_16_
- Ba_xGa_16_+_2xTi_16_- characterized by obtaining a formed body consisting of a single phase of _2xO_56
A method for producing a fiber or film-like product of barium titanogallate represented by _2xO_56. (2) The phase generated by the calcination is Ba_xGa_1
6_+_2xTi_16_-_2xO_56 is the main generation phase, and in addition, Ga_2TiO_5 phase and β-Ga_
The method according to claim 1, which is a mixed system in which a small amount of 2O_3 (β-gallia) and an unknown phase are produced.