JPH0742112B2 - Oxygen-deficient metal titanate fiber and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal titanate compound fiber used as a plastic dielectric material, for example, and a method for producing the same.

[0002]

2. Description of the Related Art Metal titanate compounds such as barium titanate and strontium titanate are used in dielectrics, semiconductors,
It is widely used as a piezoelectric material and is industrially produced in large quantities. On the other hand, fiber-shaped barium titanate is considered to be applied to grain-oriented ceramics and fiber-reinforced plastics having high dielectric constant and piezoelectricity.

Among these, as examples of applications to high dielectric constant plastics, the relative permittivity ε = 16.4 in JP-A-63-264761, and the relative permittivity ε = 25.8 in JP-A-63-63728. Has been obtained.

[0004]

However, in the prior art, in order to obtain a high dielectric constant, the compounding amount of the dielectric ceramics must be increased, and as a result, the strength of the composite material deteriorates and molding is difficult. There was a problem of becoming. An object of the present invention is to provide a filler for a composite material having both a high dielectric constant and a high strength, and a method for producing the same.

[0005]

In order to achieve the object of the present invention, the oxygen-deficient metal titanate fiber of the present invention comprises
Perovskite type AT, which is composed of at least one or more A group elements among Ca, Sr, Ba, Mg and Pb
It is represented by io _3-x (0 <x <3, x does not have to be an integer), and the fiber diameter is 0.2 to 30 μm, and the length is 10 times or more the fiber diameter. There is. Also, C
ATiO _3−X (0 <x <, which is composed of at least one or more Group A elements among a, Sr, Ba, Mg, and Pb
3, x does not have to be an integer) and the fiber diameter is 0.2 to 30 in the perovskite-type base metal salt compound represented by
μm, the length is 10 times or more of the fiber diameter, and the central part is mainly potassium titanate (K ₂ O.nTiO ₂ n = 2 to
Derived from potassium titanate such as titanium dioxide hydrate (TiO ₂ · nH ₂ O (0 <n <5), anatase titanium dioxide, rutile titanium dioxide, etc.) It is a conductor or a semiconductor, and the surface layer is mainly composed of a metal titanate compound.

Further, the above-mentioned method for producing an oxygen-deficient metal titanate compound of the present invention comprises Ca, Sr, Ba and M.
At least one element of g and Pb is included.
Compound and reducing potassium titanate or titanate
Reducing titanium dioxide fiber derived from
React in a concentrated alkaline aqueous solution under normal pressure
Characterized by Alternatively, Ca, Sr, B
at least one element out of a, Mg and Pb
Compounds containing and reductive potassium titanate or titanium
Reducible titanium dioxide fiber derived from potassium citrate and
React in a highly concentrated alkaline aqueous solution and under hydrothermal conditions.
Characterized by letting. In this way, C
Perovskite-type ATi consisting of at least one or more Group A elements among a, Sr, Ba, Mg and Pb
It is represented by O _3−X (0 <x <3, x does not have to be an integer) and is represented by ATiO ₃ having a fiber diameter of 0.2 to 30 μm and a length 10 times or more the fiber diameter. In addition to the perovskite-type metal titanate compound described above, or in addition to the above structure, the central portion is mainly reducible potassium titanate or a conductor or semiconductor derived from potassium titanate, and the surface layer is mainly Reduction consisting of metal titanate compounds
It is intended to obtain a sexual metal titanate fibers.

Namely, a reducing potassium titanate fiber is a TiO ₂ source of AO · TiO ₂ is a perovskite-type metal titanate is titanium dioxide hydrate is a derivative therefrom, anatase titanium dioxide, rutile dioxide Any of titanium fibers may be used. The strong alkaline aqueous solution may be potassium hydroxide, sodium hydroxide, lithium hydroxide or the like.

The alkaline earth metal compounds of Ca, Sr, Ba and Mg and Pb are preferably hydroxides, but chlorides, oxides, carbonates or the like can be substituted. That is, a compound that dissolves in an alkaline solution at room temperature is desirable, but any compound that dissolves at a boiling point of the alkaline solution or lower may be used. The potassium titanate fiber used in the present invention is prepared by a flux method (Japanese Patent Laid-Open No. 56-22632) or a firing method (Japanese Patent Laid-Open No. 59-4
Many manufacturing methods such as 3440) have been disclosed. Titanium hydroxide hydrate fiber is heat-treated by acid treatment of this potassium titanate fiber, anatase type titanium dioxide heat-treat titanium dioxide hydrate fiber at 800 ° C, and rutile type titanium dioxide fiber at 1100 ° C. It is obtained by The method of adding conductivity to these potassium titanate fibers can be obtained by using a solid reducing agent or by heat treatment in a reducing gas atmosphere (JP-A-61-55219).

[0009]

[Function] Oxygen-deficient metal titanate fibers are Ca, S
Of r, Ba, Mg and Pb, having a perovskite type represented by ATiO _3−X (0 <x <3, x does not need to be an integer), which consists of at least one or more A group elements, In addition, it has a structure in which the fiber diameter is 0.2 to 30 μm and the length is 10 times or more the fiber diameter, and shows its electrical characteristics. In addition to the above structure, the central portion is made of a conductor or semiconductor made of reducing potassium titanate or a derivative of potassium titanate, and the surface layer is mainly oxygen deficient.
Since it has a two-layer structure composed of a perovskite-type metal titanate salt compound, the electrical characteristics of each metal-titanate salt compound, that is, conductivity or semiconductor
It becomes a metal salt fiber and becomes a composite material with a large dielectric constant.
It It also has the tensile strength of the raw material fibers, which are whiskers.

In addition, in the production method thereof, reducible potassium titanate or a reducible titanic acid fiber derived from potassium titanate and Ca, Sr, Ba, Mg and Pb are contained in a high-concentration alkaline aqueous solution. Since the compound was mixed and reacted, a high reaction temperature can be obtained under normal pressure. Further, under hydrothermal conditions, water does not become a gas phase even at a high temperature and reacts in a liquid phase, so that a high reaction temperature can be obtained. Thus, reducing titanic acid
As a material with potassium or reducing titanic acid dioxide fiber
Oxygen-deficient metal titanate obtained by using
Composites with mixed fibers have good tensile and flexural strengths.
The mechanical strength such as degree increases.

[0011]

EXAMPLES (1) Example 1 Potassium tetratitanate represented by K ₂ O.4TiO ₂ was synthesized by a flux method. That is, a predetermined amount of titanium dioxide, barium carbonate, and potassium molybdate is mixed, heated to 1100 ° C. in a platinum crucible, cooled to 850 ° C. at a rate of 5 ° C./hour, and then the crucible is taken out of the furnace and placed in the atmosphere. It was cooled to room temperature. Subsequently, the product was washed with water to separate the flux, and potassium tetratitanate was obtained. Put this potassium tetratitanate in a closed furnace,
By performing heat treatment at 900 ° C. for 30 minutes in a hydrogen atmosphere, a blue-gray conductive reducing potassium titanate fiber was obtained.

Reducing potassium titanate 5 thus obtained
g, barium hydroxide octahydrate 11.4 g (BaO / Ti
O ₂ ≈0.75), 50 g of potassium hydroxide and pure water 3
0 cc was placed in a fluororesin container equipped with a reflux condenser, and a reaction was carried out at a liquid temperature of 150 ° C. for 10 hours. After the reaction was completed, the content was washed with water, filtered, and dried at 80 ° C. for 24 hours to obtain about 10 g of a product.

The resulting product retained the color of reducing potassium titanate and showed peaks of barium titanate and some potassium titanate as measured by powder X-ray diffraction. In addition, in the observation with the electron microscope, the shape of the starting material potassium titanate fiber was left as it was.
Since the reaction from potassium titanate to barium titanate is considered to be a dissolution and precipitation reaction from the surface, a reductive potassium titanate with a conductor at the center and a barium titanate as a dielectric or semiconductor on the surface has a two-layer structure. It is considered that the fiber having Also, the acid thus obtained
Element-deficient metal titanate fiber is used as PBT (polybutylene
Composite material in which 40 vol% of terephthalate) resin is mixed
About the conventional potassium titanate fiber
Is an oxygen-deficient material obtained by producing and reducing titanium dioxide fiber.
40% by volume of depleted metal titanate fiber mixed with PBT resin
Compared with the combined composite material, as shown in Table 2,
Oxygen-deficient metal titanate obtained by the method for producing
Fiber, compared to those obtained by conventional manufacturing methods,
It can be seen that the mechanical strength is high as a whole.

[Table 2] (2) Example 2 10 g of reducible potassium titanate prepared by the same method as in Example 1, 16.0 g of octahydrate of barium hydroxide, octadecahydrate of strontium hydroxide (BaO.SrO / TiO ₂ ≈)
0.75), potassium hydroxide 150g and pure water 60c
Put c in a fluororesin container equipped with a reflux condenser,
The reaction was carried out at a liquid temperature of 200 ° C. for 5 hours. After the reaction was completed, the content was washed with water, filtered, and dried at 80 ° C. for 24 hours to obtain about 18 g of a product.

The obtained product retained the color of reducing potassium titanate, and showed a perovskite structure similar to barium titanate and a slight peak of potassium titanate as measured by powder X-ray diffraction. In addition, in the observation with the electron microscope, the shape of the starting material potassium titanate fiber was left as it was. Since the reaction from potassium titanate to barium titanate is considered to be a dissolution and precipitation reaction from the surface, reducing center potassium titanate is a conductor, and the surface is a dielectric or semiconductor barium titanate and strontium titanate. It is considered that a fiber having a two-layer structure was obtained. (3) Example 3 4-titanic acid produced by the same method as in Example 1 was treated with 1N hydrochloric acid for 24 hours to produce a titanium dioxide hydrate fiber represented by 4TiO ₂ .2H ₂ O, This was placed in a closed furnace and treated at 900 ° C. for 30 minutes in a hydrogen atmosphere to obtain a conductive reducing titanium dioxide fiber.

10 g of this reducible titanium dioxide fiber and 19.8 g of barium hydroxide octahydrate (BaO / TiO ₂ =
0.5), 50 g of potassium hydroxide and 30 cc of pure water were placed in a fluororesin container equipped with a reflux condenser and reacted at a liquid temperature of 150 ° C. for 10 hours. After the reaction was completed, the content was washed with water, filtered, and dried at 80 ° C. for 24 hours to give about 1
5 g of product was obtained.

The resulting product retained the color of reducing titanic acid and showed peaks of barium titanate and anatase-type and rutile-type titanium dioxide as measured by powder X-ray diffraction. In addition, in observation with an electron microscope, the shape of the reducing titanium dioxide fiber as the starting material was left as it was. Since the reaction from titanium dioxide to barium titanate is considered to be a dissolution and precipitation reaction from the surface, it has a double-layered structure in which the central part is a conductive reducing titanium dioxide and the surface is a dielectric or semiconductor barium titanate. It is considered that the fiber was obtained. (3) Example 4 10 g of reducing potassium titanate prepared by the same method as in Example 1 and 36.6 g of barium hydroxide octahydrate (BaO /
TiO ₂ = 1.2), potassium hydroxide 50 g, pure water 60
cc was filled in a closed pressure vessel, and the reaction was carried out at 250 ° C. for 5 hours. After the reaction was completed, the content was washed with water, filtered, and dried at 80 ° C. for 24 hours to obtain about 24 g of a product.

The obtained product had a slight color of reducing barium titanate, and showed a barium titanate peak as measured by powder X-ray diffraction. In addition, in the observation with an electron microscope, the fiber shape of the starting material potassium titanate was left as it was. The product is considered to be a dielectric or semiconductor barium titanate because of its color tone. (4) Comparative Example 4 Potassium titanate 5 prepared by the same method as in Example 1
g, barium hydroxide octahydrate 11.4 g (BaO / Ti
O ₂ = 0.75), 50 g of potassium hydroxide and pure water 3
0 cc was placed in a fluororesin container equipped with a reflux condenser, and a reaction was carried out at a liquid temperature of 150 ° C. for 10 hours. After the reaction was completed, the content was washed with water, filtered, and dried at 80 ° C. for 24 hours to obtain about 10 g of a product.

The powder X-ray diffraction of the obtained product showed peaks of barium titanate and some potassium titanate. In addition, in the observation with the electron microscope, the shape of the starting material potassium titanate fiber was left as it was. Since the reaction from potassium titanate to barium titanate is considered to be a dissolution and precipitation reaction from the surface, it has a two-layer structure in which the central part is potassium titanate as an insulator and the surface is barium titanate as a dielectric or semiconductor. It is believed that the fibers that it possessed were obtained.

Here, the dielectric constants of the composite molded articles obtained by compounding the fibers obtained in Examples 1, 2 and 4 and Comparative Example with PBT (polybutylene terephthalate) at a ratio of 40 vol% are shown in Table 1. Shown in.

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION As is clear from Table 1, the present invention
The material in which the oxygen-deficient metal titanate fiber is composited has a dielectric constant that is at least twice as high as that of the conventional material in which oxygen-deficient ATiO ₃ fiber is not composited . Also, the strength is superior to that of the conventional one. As a result, it is possible to provide a highly reliable material having a good crystallinity without breaking the fiber shape. Further, the oxygen-deficient titanium of the present invention
According to the method for producing metal acid salt fiber, Ca, Sr, B
at least one element out of a, Mg and Pb
Compounds containing and reductive potassium titanate or titanium
Reducible titanium dioxide fiber derived from potassium citrate and
To react under high pressure in a high-concentration alkaline aqueous solution
Therefore, the equipment required for producing the oxygen-deficient metal titanate fiber can be simplified, and the production cost can be reduced. There is also no danger of work. On the other hand, when performing under hydrothermal conditions,
Since the reaction time can be shortened, the manufacturing process becomes efficient. It
In addition, the oxygen-deficient chia obtained by the production method of the present invention.
Composite materials mixed with metal tantalate fibers are produced by the conventional method.
Compared to the composite material in which the fibers obtained by
Increased mechanical strength, which provides superior composite materials
can do.

On the other hand, when the reaction is carried out under hydrothermal conditions, the reaction time can be shortened, so that the production process becomes efficient.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-237100 (JP, A) JP-A-3-69511 (JP, A) JP-A-3-218926 (JP, A) JP-A-2- 167823 (JP, A) JP 1-83515 (JP, A) JP 63-30399 (JP, A) JP 62-21799 (JP, A) JP 62-7160 (JP, B2)

Claims (4)

[Claims] 1. ATiO comprising at least one or more Group A elements among Ca, Sr, Ba, Mg and Pb.
_In a perovskite-type metal titanate fiber represented by _3-X (0 <x <3, x does not have to be an integer),
The fiber diameter is 0.2 to 30 μm, and the length is 10 with respect to the fiber diameter.
Oxygen-deficient metal titanate fiber characterized by being more than doubled. 2. ATiO, which comprises at least one or more A group elements of Ca, Sr, Ba, Mg and Pb.
_{In the} perovskite-type metal titanate compound represented by _3-X (0 <x <3, x does not have to be an integer), the fiber diameter is 0.2 to 30 μm, and the length is relative to the fiber diameter. Oxygen , which is 10 times or more, and whose central portion is a conductor or semiconductor mainly composed of potassium titanate or a derivative of potassium titanate, and whose surface layer is mainly composed of a metal titanate compound. Defective metal titanate fiber. 3. A compound containing at least one element selected from the group consisting of Ca, Sr, Ba, Mg and Pb, and reduction.
And by reducing titanium dioxide fibers derived from potassium sex potassium titanate or titanic acid in high concentration alkaline aqueous solution, and oxygen according to claim paragraph 1 or 2, wherein the reaction is carried out in the normal pressure A method for producing a deficient metal titanate fiber. Wherein Ca, Sr, Ba, of Mg and Pb, and compounds containing at least one element, reducing <br/> derived from potassium titanate or potassium titanate reducible titanium fiber dioxide The method for producing an oxygen-deficient metal titanate fiber according to claim 1 or 2, wherein and are reacted in a high-concentration alkaline aqueous solution under hydrothermal conditions.