JPH0432764B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing a fibrous alkali metal titanate, and more particularly to a method for producing a fibrous alkali metal titanate comprising a titanium hydroxide slurry and an oxygen-containing alkali metal compound. Fibrous alkali metal titanates are used as plastic reinforcement materials, friction materials, filtration materials, battery diaphragms,
Known as a pigment and insulating material. <Prior Art> Various methods have already been proposed for producing fibrous alkali metal titanates. That is, firing method,
Melting methods, hydrothermal methods, flux methods, melt methods, etc. are known. Generally, in any of the methods, titanium oxide and a basic oxygen-containing alkali metal compound are often used as raw materials. Recently, fibrous alkali metal titanates have been expected to be used as a substitute for asbestos, but the currently available fibrous alkali metal titanates have a smaller aspect ratio than asbestos and cannot be used as a practical substitute for asbestos. The current situation is that this is not the case. Japanese Patent Publication No. 42-27264 describes hydrous titania, anatase TiO ₂ as a titanium source, a TiO ₂ product in a commercially available sulfate process for producing pigments, electronic material powders, catalysts, etc., and well-purified anatase pigment. , crushed rutile ore and commercially available ilmenite. Furthermore, as basic oxygen-containing alkali metal compounds, alkali metal hydroxides, alkali metal carbonates, and the like are disclosed. The above-mentioned special public service 1977-
No. 27264 synthesizes a fibrous alkali metal titanate by firing a non-liquid mixture of the titanium source and a basic oxygen-containing alkali metal compound at 200 to 1150°C, and has a diameter of 0.005 to 0.1 micron and a length of 0.005 to 0.1 micron. Calcinate at 200 to 850 °C to produce colloid-rich products with particle sizes at least 10 times the diameter of the colloid.
Also, the diameter is 0.1 to 0.6 microns and the length is 10 to 100 times the diameter.
If the pigment type with twice the particle size is produced, it is fired at 850-975℃, and the insulated type with a particle size of 0.6-3 microns in diameter and 100-1000 times the diameter is produced. 975-1150 for manufacturing things
It is stated that the desired fibrous alkali metal titanate can be obtained by firing at .degree. Also disclosed is a manufacturing method in which an alkali metal halide is added to a non-liquid mixture of raw materials and fired. However, it is difficult to separate the target material that has grown as long fibers during firing, and due to the fibers breaking during the fibrillation process, the fiber length of the obtained fibrous alkali metal titanate is essentially 10 to 20 μm, and the aspect ratio is The ratio was also around 50, which was not fully satisfactory, and its industrial use was extremely limited. <The present invention, purpose and structure> The purpose of the present invention is to provide a method for producing a fibrous alkali metal titanate that can be easily separated from the fibrous nodule produced by firing and prevents fiber breakage during the defibration process. It's about doing. Another object of the present invention is to provide a method for producing a fibrous alkali metal titanate having a large aspect ratio and high strength. In producing a fibrous alkali metal titanate, the present invention adds an oxygen-containing alkali metal compound to a titanium hydroxide slurry containing 10 to 35% by weight of titanium hydroxide in terms of TiO ₂ and whose pH is in the acidic range. The present invention relates to a method for producing a fibrous alkali metal titanate, which is characterized in that the slurry is neutralized, the slurry is mixed with an oxygen-containing alkali metal compound, dried, and then fired at a temperature of 900 to 1300°C. Examples of the titanium hydroxide slurry of the present invention include those produced industrially as an intermediate in a titanium oxide pigment production process using a sulfuric acid method. This is a titanyl sulfuric acid solution obtained by cooking and extracting titanium ore or titanium slag with sulfuric acid, purified, thermally hydrolyzed, and bleached as necessary (hereinafter referred to as wet cake).
The composition is roughly as follows. TiO(OH) ₂ 40.4-49.0% by weight (33-40% by weight in terms of TiO2) _{H2SO4 2.0-3.2} % by weight (6.1-9.8% by weight based on _TiO2 ) _H2O 47.8-57.6 _% by weight Furthermore, water is added to form a slurry having a concentration of 10 to 35% by weight in terms of TiO ₂ . In the present invention, the titanium hydroxide slurry and the oxygen-containing alkali metal compound as described above are mixed, dried, and then fired at a temperature of 900 to 1300°C to obtain the desired fibrous alkali metal titanate with a high aspect ratio. is obtained. In the above mixing step, the oxygen-containing alkali metal has both the role of a neutralizer for sulfate groups in the titanium hydroxide slurry and the role of a constituent component of the fibrous alkali metal titanate. As a result of examining various neutralizing agents, that is, alkaline compounds, the present inventor found that the slurry neutralized with the oxygen-containing alkali metal compound of the present invention is the only titanium source capable of producing fibrous alkali metal titanate with a high aspect ratio. I found out. For example, if the slurry is neutralized with ammonia, the growth of the target fibers will be inhibited, which is not preferable. The oxygen-containing alkali metal compound used in the present invention is a compound that generates M ₂ O (M is an alkali metal) during firing, such as oxides, hydroxides, carbonates, and bicarbonates of potassium, sodium, cesium, and rudybium. , oxalates, nitrates, etc. Examples of such compounds are _K2O , KOH, _{K2CO3 ,
KHCO3} , _K2C2O4 , _KNO3 , _Na2O , _{NaOH ,}
Na ₂ CO ₃ , NaHCO ₃ , Na ₂ C ₂ O ₄ , NaNO ₃ ,
_Cs2O , _Cs2OH , _{Cs2CO3 , CsHCO3 , Cs2C2O4 ,
CsNO3} , _Rb2O , _RbOH , _Rb2CO3 , _RbHCO3 ,
Examples include Rb ₂ C ₂ O ₄ and RbNO ₃ . The mixing ratio of the titanium hydroxide slurry and the oxygen-containing alkali metal compound is preferably a molar ratio of 3 to 3.5 in terms of _TiO2 / _M2O , but the present invention is not limited to this molar ratio. In the present invention, since the oxygen-containing alkali metal compound is also used for neutralizing the titanium hydroxide slurry, it is important to mix the oxygen-containing alkali metal compound in a slight excess to the desired molar ratio. After neutralization, the oxygen-containing alkali metal compound may be further added in a reaction amount, or the total amount of the neutralization amount and the reaction amount may be added. Further, a small amount of potassium chloride or the like may be added as a reaction aid. Since the blended raw material used in the present invention is subjected to a calcination reaction, it is necessary to remove water from the mixed slurry, and a heating and drying method is suitable as a method for this purpose. In order to increase reactivity, it is more convenient to press to shape and increase density. At this time, it is better to add some organic glue, surfactant, etc. to the above-mentioned blend raw materials for better moldability. As for the press pressure, you should choose one that can be used for modeling, but generally 20~
A pressure of 300 Kg/cm ² , preferably 50 to 150 Kg/mm ² is suitable. Firing can be carried out over a wide temperature range, but
Preferably 900~1300℃, more preferably 1000~
It is best to do this at a temperature of 1200℃. The firing time is preferably about 15 minutes to 6 hours, more preferably about 30 minutes to 3 hours. Further, it is preferable to slowly cool the alkali metal titanate obtained by the heating reaction in order to cause sufficient fiber growth. Slow cooling can be carried out by lowering the temperature over a wide range of temperatures, but usually between 900 and
A range of 950°C is preferred. After slow cooling, it is preferable to further bake or repeat the above-mentioned firing and slow cooling two or more times, since fibers with even higher aspect ratios can be obtained. The product obtained by the above reaction is a nodule,
It is rich in fiber. In the present invention, the fibrous alkali metal titanate is defibrated from this nodule to obtain one with a high aspect ratio. In the defibration step, the fiber material produced above is put into water and defibrated using a disper stirring method or the like. In this case, it is preferable to leave it in water for at least 1 hour to allow it to fully blend in with the water. Various known defibrators can be used. The desired fibrous alkali metal titanate can be obtained by filtering and drying the thoroughly defibrated dispersion rich in fibers. The fibrous alkali metal titanate obtained in the present invention has the general formula M ₂ O・nTiO ₂ (M is an alkali metal,
n is a real number of 2 to 8 or a mixture thereof), the fiber diameter is preferably 0.1 to 1 μm, and the fiber length is preferably in the range of 50 to 300 μm. Examples and comparative examples are listed below. Example 1 Titanium hydroxide slurry (as chemical analysis value)
TiO ₂ 29.9% by weight, H ₂ SO ₄ 4.17% by weight) were placed in a container equipped with a high-speed stirrer to neutralize and react with the H ₂ SO ₄ contained in the titanium hydroxide slurry. Sodium hydroxide is added so that the molar ratio of TiO ₂ /K ₂ O is 3.3, and the mixture is thoroughly mixed and dispersed. Next, this mixed thriller was left to dry in a heating dryer overnight, and then finely ground. This diameter is 60
The molded product obtained by molding at a pressure of 200 Kg/cm ² using a 1.0 mm mold was reacted for 7 hours in a Matsufuru furnace at 1100°C. After crushing the obtained reaction product and soaking it in water overnight, washing the reaction product separately,
After drying, fibrous potassium titanate was obtained. The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1. Example 2 A molded product for reaction obtained in the same manner as Example 1 was reacted for 4 hours in a Matsufuru furnace at 1100°C, and then slowly cooled to 950°C at a rate of 20°C/hr. has ended. The reaction product taken out from the furnace was defibrated in the same manner as in Example 1 to obtain fibrous potassium titanate. The yield and fiber properties were as shown in Table 1. Example 3 Fibrous potassium titanate was obtained by carrying out the same operation as in Example 1, except that potassium carbonate (first grade reagent) was used instead of potassium hydroxide for reaction in Example 1. The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1. Example 4 Potassium carbonate (grade 1 reagent) was added to the same titanium hydroxide slurry used in Example 1 as an alkali metal compound for neutralization and reaction at a TiO ₂ equivalent/K ₂ O molar ratio of 3.5. After addition and mixing, the same operation as in Example 1 was performed to obtain fibrous potassium titanate. The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1. Comparative Example 1 A predetermined amount of ammonia water necessary for neutralization was added to the same titanium hydroxide slurry as used in Example 1, and then potassium carbonate for reaction was mixed with TiO ₂ /K ₂ O.
were added and mixed so that the molar ratio was 3.3, and the same operation as in Example 1 was performed to obtain fibrous potassium titanate. The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1. Comparative Example 2 A titanium hydroxide slurry that had been neutralized in the same manner as in Comparative Example 1 was filtered, washed, and then placed in a dryer to obtain dry hydrous titanium. Using the obtained hydrated titania, potassium carbonate (grade 1 reagent) was added so that the molar ratio of TiO ₂ /K ₂ O was 3.3.
After thoroughly mixing it using a powder mixer, mix it into a powder with a diameter of 60
Molded using a mm mold at a pressure of 200Kg/ ^cm2 ,
The obtained molded body was reacted for 7 hours in a Matsufuru furnace at 1100°C. The obtained reaction product was roughly framed and immersed in water, and the reaction product was filtered, washed, and dried to obtain fibrous potassium titanate. The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1. Comparative Example 3 Commercially available anatase-type titanium oxide [manufactured by Teikoku Kako Co., Ltd.]
and added potassium sulfate (1st grade reagent) equivalent to 25% by weight based on TiO ₂ , and added potassium carbonate (1st grade reagent) for reaction at a molar ratio of TiO ₂ /K ₂ O of 3.3. Example 1 except that the amount was added and mixed.
Fibrous potassium titanate was obtained in the same manner as above.
The yield and fiber properties of the obtained fibrous potassium titanate were as shown in Table 1.

[Table] <Effects of the present invention> According to the production method of the present invention, it is easy to separate the fibers produced by firing from the fibrous nodules, and it is possible to prevent the fibers from breaking during the defibration process. A fibrous alkali metal titanate having a large aspect ratio and high strength can be obtained.

Claims (1)

[Claims] 1. In producing fibrous alkali metal titanate, an oxygen-containing alkali is added to a titanium hydroxide slurry containing 10 to 35% by weight of titanium hydroxide in terms of TiO ₂ and whose pH is in the acidic range. 1. A method for producing a fibrous alkali metal titanate, which comprises adding a metal compound to neutralize the slurry, mixing the slurry with an oxygen-containing alkali metal compound, drying, and then firing at a temperature of 900 to 1300°C. 2. The method according to claim 1, wherein in mixing the titanium hydroxide slurry and the oxygen-containing alkali metal compound, the molar ratio of TiO ₂ /M ₂ O (M is an alkali metal) is 3 to 3.5. 3. The method according to claim 1, wherein the oxygen-containing alkali metal compound is at least one selected from the group of alkali metal oxides, hydroxides, and carbonates. 4. The fibrous alkali metal titanate is a compound represented by the general formula _M2O.nTiO2 (M is an alkali metal, n is a real number _from 2 to 8 or a mixture thereof), according to claim 1. the method of.