JPH0543236A - Production of combined barium hexatitanate fiber - Google Patents

Abstract

PURPOSE:To synthesize combined barium hexatitanate fibers having excellent heat insulating property, heat and chemical resistances and high dielectric constant. CONSTITUTION:The oxides of Ti, K and Ba or compds. of Ti, K and Ba forming oxides when heated are mixed in 1:(0.1-1):0.5 molar ratio of TiO2K2 OBaO and this mixture is mixed with K2MoO4 or a K2O-MoO3 mixture as a flux in 20:80-40:60 molar ratio. A melt is formed by heating the mixture to >=900 deg.C and a fibrous material based on potassium tetratitanate having laminar structure is synthesized by slowly cooling the melt to 700-800 deg.C. Interlaminar K ions are partially extracted by acid treatment to form a compsn. represented by a formula (K1-xBax)Ti6O13 (where x is 0.5-1.0) and then the fibrous material is heated to a temp. between 1,000 deg.C and the melting temp. Tunnel structure is formed and combined barium hexatitanate fibers having the above-mentioned compsn. are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite barium hexatitanate fiber having excellent heat resistance, heat insulation, high dielectric properties and chemical resistance.

[0002]

2. Description of the Related Art Conventionally, potassium hexatitanate fibers have been synthesized by various methods. This fiber material has excellent chemical resistance such as heat resistance, heat resistance and alkali resistance, and is therefore excellent as a heat resistance and heat insulating material and a reinforcing material for plastics, metals, ceramics, etc. If barium can be solid-dissolved in the potassium salt of this potassium hexatitanate, a composite barium hexatitanate fiber having the functionality of highly dielectric barium hexatitanate can be synthesized. Barium fiber was not synthesized.

An object of the present invention is to provide a method for synthesizing a novel composite barium hexatitanate fiber.

[0004]

Means for Solving the Problems The present inventor has conducted extensive research into the manufacturing process and conditions under which a composite barium hexatitanate fiber having a tunnel structure can be synthesized, and as a result, has found a new synthetic process. Is.

That is, according to the present invention, titanium oxide, potassium oxide, barium oxide, or a titanium compound, a potassium compound, or a barium compound which produces these oxides by heating, in a molar ratio of TiO ₂ : K ₂ O: BaO = 1: 0.1: 0.
The mixture is mixed at a ratio of 1 to 1: 0.5: 0.5, and this mixture and flux K ₂ MoO ₄ (or a mixture of K ₂ O and MoO ₃ ) is used.
In a molar percentage of 20:80 to 40:60 and heated to 900 ° C. or above to form a melt, then 7
The fibrous material mainly composed of a potassium tetratitanate structure having a layered structure is synthesized by gradually cooling to 00 to 800 ° C., and then treated with an acid to extract a part of interlayer potassium ions, and the composition thereof is (K ₂ _xBax) Ti ₆ O ₁₃ (x = 0.5 to 1.0), which is heat-treated at a temperature of 1000 ° C. or higher to a melting temperature or lower to form a tunnel structure.
The gist is the method for producing (K ₂ _xBax) Ti ₆ O ₁₃ fibers.

The present invention will be described in more detail below.

[0007]

[Action]

In the synthesis process according to the present invention, first, titanium oxide, potassium oxide, barium oxide, or a titanium compound, a potassium compound, or a barium compound which forms these oxides by heating, is used in a molar ratio of TiO ₂ : K ₂ O. : Ba
Mix in a ratio of O = 1: 0.1: 0.1 to 1: 0.5: 0.5. Preferably TiO ₂ : K ₂ O: BaO = 1: 0.1
Mix in a ratio of 5: 0.15 to 1: 0.2: 0.2.

Then, this mixture is mixed with flux K ₂ MoO ₄ (or a mixture of K ₂ O and MoO ₃ ) in a molar ratio of 20:80 to 40:60. It is preferably mixed at 30:70 mol%.

Next, this mixture is heated to 900 ° C. or higher, preferably 1000 to 1100 ° C. to be melted to form a melt, and the melt is gradually cooled to 700 to 800 ° C. The slow cooling rate is preferably 1 ° C / h to 10 ° C / h, more preferably about 5 ° C / h. By this slow cooling operation, a fibrous material mainly composed of a composite barium tetratitanate fiber having a layered structure and potassium tetratitanate type structure is synthesized by a dissolution-precipitation reaction. Here, if the material is rapidly cooled to the above temperature range, it becomes amorphous or fine fibers and long fibers cannot be obtained, so it should be avoided. The reason for synthesizing the fibrous material mainly composed of the composite barium tetratitanate fiber as the intermediate product is that it has a layered structure and has been clarified to be the longest fiber.

Next, the fibrous material mainly containing the obtained composite barium tetratitanate fiber is separated from the flux. Flux can be easily dissolved in hot water. Then, after thoroughly washing with water, a part of interlayer potassium is extracted by an acid treatment of immersing the fiber in an acid aqueous solution. The concentration of the acid aqueous solution is 0.
When treated with an aqueous solution of 01N hydrochloric acid at a rate of 1000 ml per 2 g of fiber, (K ₂ _xBax) Ti ₆ O ₁₃ (x =
A composition of 0.5-1.0) is achieved. If x is less than 0.5, the dielectric properties will be low, and if it exceeds 0.1, the growth of the fibers will be affected, and the higher the Ba content, the shorter the fibers, which is not preferable.

Then, the treated fiber is washed with water to obtain 10
00 ° C or higher and melting temperature or lower, preferably 1200 to 125
Heat treatment at 0 ° C. for 1 hour or more produces a composite barium hexatitanate fiber having a tunnel structure and a (K ₂ —xBax) Ti ₆ O ₁₃ composition.

Next, examples of the present invention will be described.

[0014]

EXAMPLE A powdery raw material is used in a molar ratio of TiO ₂ : K ₂ CO ₃ :
BaCO ₃ = 1.0: 0.17: 0.17 mixed in the ratio,
The resulting mixture was mixed with flux K ₂ MoO ₄ powder in a molar percentage of 30: 70%. Fill a 100 ml platinum crucible with about 100 g of the whole mixture,
Heat at 0 ° C for 1 hour, then at a cooling rate of 4 ° C / h to 80
The fibers were synthesized by gradually cooling to 0 ° C.

After the gradual cooling, the crucible was taken out into the atmosphere and allowed to cool to room temperature. The fibers were separated by immersing the crucible in hot water to dissolve the flux. The separated fibers were washed well with water and dried at about 100 ° C.

Next, this fiber material was treated with a 0.01N hydrochloric acid aqueous solution at a liquid volume of 500 ml per gram for 1 hour in order to extract a part of potassium for controlling the composition. After this acid treatment, it was washed with water, dried, and then heat-treated at 1200 ° C. for about 1 hour. The state of the obtained fiber was almost unchanged. When powdered and identified by X-ray diffractometry, it was a potassium hexatitanate-type structure single phase having a tunnel structure. Furthermore, chemical analysis by the results of examining the composition, the composition formula was _{(K 1. 2 Ba 0.} 8) Ti 5. 8 O 13.

[0017]

As described above, according to the present invention,
A composite barium hexatitanate fiber having a tunnel structure can be synthesized. Since this fiber has excellent heat resistance, heat insulation, high dielectric properties, and chemical resistance, it can be used for various purposes.

Claims (1)

[Claims] 1. A titanium oxide, potassium oxide, barium oxide, or a titanium compound, a potassium compound, and a barium compound, which produce these oxides by heating, in a molar ratio of Ti.
O ₂ : K ₂ O: BaO = 1: 0.1: 0.1 to 1: 0.5:
The mixture is mixed at a ratio of 0.5, and this mixture and flux K ₂ MoO ₄ (or a mixture of K ₂ O and MoO ₃ ) are mixed at a molar ratio of 20:80 to 40:60, and the temperature is 900 ° C or higher. To form a melt, which is then gradually cooled to 700 to 800 ° C. to synthesize a fibrous material mainly composed of a potassium tetratitanate structure having a layered structure, and then acid-treated to remove one of the potassium ions between layers. Part and extract its composition from (K ₂ _xBax) Ti
A composite barium hexatitanate (K ₂ _xBax) Ti, which is characterized as ₆ O ₁₃ (x = 0.5 to 1.0) and is heat-treated at a temperature of 1000 ° C. or higher to a melting temperature or lower to form a tunnel structure. ₆
O ₁₃ fiber manufacturing method.