JPH0478734B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to fibers or fibers of a compound having an orthorhombic tunnel structure and having a composition represented by the general formula A1-xTi _2+x M _5-x O ₁₂ . This invention relates to a method for producing a film-like material.

(Prior art) General formula A _1-x Ti _2+x M _5-x O ₁₂ (However, A: Na, K,
Rb or Cs, M: Al, Ga, Fe or Cr, x: 0~
Compounds with an orthorhombic tunnel structure shown by 0.5) have excellent heat resistance and heat insulation properties, and are useful as heat resistance and heat insulation materials, and are also used as reinforcing materials for plastics, metals, cement, etc.

Conventionally, the flux method has been known as a method for producing this compound (Japanese Patent Application No. 41160/1982). In this method, alkali molybdate is used as a flux, the material is slowly cooled from a high temperature, and a fibrous single crystal is grown through a dissolution-precipitation reaction.

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 a method in which ertel silicate is mixed into a viscous solution containing polyaluminoxane, an inorganic polymer having a main chain consisting of -Al-O-, followed by 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, both the flux method and the method for producing polycrystalline fibers have the following problems.

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 dope is important because the fibers are spun using a spinning solution, and the physical properties of the solution such as viscosity, spinnability, uniformity, and stability are important. In addition to these factors, 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 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 there are problems such as the particle size, amount added, dispersion state, etc. of solid particles constituting the spinning dope slightly affect spinnability, making it difficult to control.

The present invention solves the problems of the spinning dope in the conventional method when producing fibers or membranes of a compound having orthorhombic tunnels represented by the general formula A _1-x Ti _2+x M _5-x O ₁₂ . The purpose of the present invention is to provide a method that solves the above problems, allows easy adjustment of the viscosity of the spinning dope, has excellent spinnability, uniformity, and stability, has good spinnability, and is easy to manufacture. That is.

(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 by adding it to a specific organic acid aqueous solution at a predetermined ratio, dissolving and concentrating it, a viscous liquid suitable for spinning can be obtained, and that the desired purpose can be achieved by extruding, molding, and baking this liquid. , completed the present invention.

That is, the present invention provides general seats A _1-x Ti _2+x M _5-x
O ₁₂ (However, A: Na, K, Rb or Cs, M: Al,
When producing a compound having an orthorhombic tunnel structure represented by Ga, Fe or Cr, An inorganic salt is used, a carbonate of the component is used as the component A, and each raw material in the composition ratio shown by the above general formula is 1.0% relative to the total amount of the metal alkoxide.
It is added to an aqueous solution of single or mixed organic acids such as citric acid or tartaric acid in an amount of twice the mole or more, dissolved and concentrated to form a spinning solution, which is then spun to form a fibrous or membrane-like product. A method for producing a fiber or film-like product of a compound having an orthorhombic tunnel structure having a composition represented by the general formula A _1-x Ti _2+x M _5-x O ₁₂ , characterized by firing at ℃ This is a summary.

The present invention will be explained in detail below.

(Function) First, as a raw material for producing a substance having an orthorhombic tunnel structure and having a composition represented by the above-mentioned general formula A _1-x Ti _2+x M _5-x , the following specific component raw materials are used.

Titanium alkoxide is used as the Ti component.
Examples of the titanium alkoxide include titanium tetrase propoxide and titanium tetra-normal butoxide.

The M component is Al, Ga, Fe, or Cr, and its alkoxide, organic salt, or inorganic salt is used as a raw material for the M component. For example, if the M component is Al,
Examples of alkoxides include aluminum triisopropoxide, aluminum trinormal butoxide, aluminum triethoxide, etc.; organic salts include acetate; and inorganic salts include chloride, sulfate, nitrate, etc. Can be mentioned.

Even when the M component is Ga, it is possible to use the compounds shown in the case of Al, but nitrates are mainly used because of their ease of availability and handling. Of course, it goes without saying that it is not limited to nitrates.

Furthermore, when the M component is Fe or Cr,
It is possible to use compounds such as those shown in the case of Al.

Incidentally, titanium alkoxide and aluminum alkoxide react very easily with citric acid and tartaric acid to obtain a transparent and uniform solution, which can be converted into an oxide by firing.

In the thus obtained transparent homogeneous solution, M
Even if an organic salt or an inorganic salt of a metal component such as Al, Ga, Fe or Cr is added as a component, the solution will not become non-uniform.

In addition, carbonate of Na, K, Rb, or Cs is used as component A, but carbonate as an alkali metal component such as Na, K, Rb, or Cs releases CO ₂ when mixed with an organic acid aqueous solution (described later). The solution becomes clear and homogeneous.

These raw materials are blended so as to have the composition ratio of the above general formula.

Next, these manufacturing raw materials are mixed with citric acid,
When tartaric acid is added to a single or mixed organic acid aqueous solution and dissolved and concentrated, it becomes a viscous liquid with stringiness.
In this case, the amount of the single or mixed organic acids such as citric acid and tartaric acid needs to be at least 1.0 times the total mole of the metal alkoxide. If the amount is less than 1.0 times the mole, the resulting spinning stock solution may become non-uniform or exhibit no stringiness, and
It becomes difficult to solidify and cannot be formed into fibrous or film-like materials.

As for the aqueous solution of the organic acid, it is preferable to use water in an amount of 20 to 50 times the mole of metal alkoxide.

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.

The obtained fibrous or film-like material is subjected to water removal,
After heating in the air at 700 to 1000°C to decompose and remove organic substances, firing at 1200 to 1400°C yields the desired compound fiber or membrane having an orthorhombic tunnel structure. However, if the temperature is lower than 1200°C, sintering will not be completed, and if the temperature exceeds 1400°C, it will start to melt, which is not preferable.

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

Example 1 (a) This example is an example in which a fiber having the compositional formula Na _1-x Ti _2+x Al _5-x O ₁₂ (x=0) is synthesized using citric acid as the organic acid.

First, titanium tetraisopropoxide was added to a solution of 13.44 g of citric acid dissolved in 50 ml of distilled water.
A clear solution was obtained by dropping 5.68 g and stirring for about half a day. 10.86 g of aluminum triisopropoxide was added to this solution, and by stirring for about one day, a transparent and uniform solution was obtained.
Furthermore, 0.53 g of sodium 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.

The resulting solution was heated to 100°C and concentrated until the viscosity reached 100 poise. When this was allowed to cool, the viscosity gradually increased and it had good spinnability.

Next, the material in an appropriate viscous state is extruded through a nozzle in a dry atmosphere at room temperature, and a diameter of 5 to 50
A long fiber of 100 μm was obtained. This fiber was colorless and transparent.

After drying the obtained fibers at 100℃ overnight,
It was heat treated at 1300°C for 2 hours and then baked at 1300°C for 10 hours.

The obtained fibers were titanoaluminate fibers having an orthorhombic tunnel structure with a composition of Na ₁ Ti ₂ Al ₅ O ₁₂ .

(b) This example uses tartaric acid as the organic acid and the composition formula
This is an example in which a fiber of Na _1-x Ti _2+x Al _5-x O ₁₂ (x=0) is synthesized.

First, a solution of 10.51 g of tartaric acid dissolved in 50 ml of distilled water was used as an organic acid aqueous solution.
In the same manner as in (a), long fibers having a NaTi ₂ Al ₅ O ₁₂ composition were obtained.

(c) This example is an example in which a fiber having the composition formula Na _1-x Ti _2+x Al _5-x O ₁₂ (x=0.2) is synthesized using aluminum acetate as the M component.

Basic aluminum acetate 15.31 as Al component
In the same manner as in Example 1(a) except that g was used.
A long fiber with a composition of N _90.8 Ti _2.2 Al _4.8 O ₁₂ was obtained.

(d) This example is an example in which a fiber having the compositional formula Na _1-x Ti _2+x Al _5-x O ₁₂ (x=0.2) is synthesized using aluminum nitrate as the M component.

N _2.8 Ti _2.2 was prepared in the same manner as in Example 1(a) except that 10.66 g of aluminum nitrate was used as the Al component.
Long fibers of Al _4.8 O ₁₂ composition were obtained.

Example 2 This example uses citric acid as the organic acid and the composition formula
This is an example in which a fiber of K _1-x Ti _2+x Ga _5-x O ₁₂ (x=0.2) is synthesized.

First, 5.68 g of titanium tetraisopropoxide was added dropwise to a solution of 4.61 g of citric acid dissolved in 30 ml of distilled water, and a transparent solution was obtained by stirring for about half a day. Add 12.79g of gallium nitrate to this solution,
A clear homogeneous solution was obtained. Further, 0.50 g of potassium carbonate was gradually added to this solution, and the mixture was stirred until it became transparent and homogeneous. All the above operations were performed at room temperature.

The resulting solution was heated to 100°C and concentrated until the viscosity reached 100 poise. When this was allowed to cool, the viscosity gradually increased and it had good spinnability.

Next, the material in an appropriate viscous state is extruded through a nozzle in 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 1300°C for 2 hours, and then baked at 1300°C for 10 hours.

The obtained fibers were titanogallate fibers having an orthorhombic tunnel structure with a composition of K _0.8 Ti _2.2 Ga _4.8 O ₁₂ .

In addition, although each of the above examples has been shown using representative examples of the A component and the M component, it goes without saying that other A components and M components can be used in the same manner.

In addition, when spinning, a film-like product can be obtained by using a slit instead of a nozzle, and if it is extruded through a thick diameter nozzle and fired and blown off with flame,
Ultra-fine short fibers are obtained.

(Effects of the Invention) As detailed above, according to the present invention, when producing fibers or membrane-like products having the above compositional formula, it is easy to adjust the viscosity of the spinning dope 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 easily and inexpensively obtained by spinning.

Claims (1)

[Claims] 1 General formula A _1-x Ti _2+x M _5-x O ₁₂ (However, A: Na,
K, Rb or Cs, M: Al, Ga, Fe or Cr, x:
0 to 0.5), titanium alkoxide is used as the Ti component, an alkoxide, organic salt or inorganic salt of the component is used as the M component, and as the A component. Using the carbonate of the component, each raw material having the composition ratio shown by the above general formula is added to an aqueous solution of citric acid or tartaric acid alone or a mixed organic acid in an amount of 1.0 times the mole or more based on the total amount of the metal alkoxide. After dissolving and concentrating to obtain a spinning solution, this is then spun to form a fibrous or membrane-like product, and then
General formula characterized by firing at ~1400℃
A method for producing fibers or membranes of a compound represented by A _1-x Ti _5+x M _2-x O ₁₂ .