JPH075440B2 - Method for producing long-fiber alkali metal titanate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for producing a long-fibrous alkali metal titanate salt, and more specifically, a method for fiberizing alkali hexatitanate and octatitanate octane crystalline. Concerning the law. The long fibers of these compounds are excellent in mechanical properties such as high bending strength, and also have characteristics such as high electrical insulation, thermal or chemical stability, and negative thermal conductivity-temperature coefficient characteristics. It is a material. Therefore, plastic reinforcement material, anti-friction material,
Widely used for battery diaphragms, heat insulating structural materials, excess materials, pigments, etc.

(Prior Art) Various methods have already been proposed as a method for producing a fibrous alkali metal titanate. That is, a firing method, a melting method, a hydrothermal method, a flux method and a melt method are known. Generally, in any of the methods, there are many examples in which titanium oxide and a basic oxygen-containing alkali metal compound are adopted as the raw materials.

Recently, fibrous alkali metal titanate has been expected as a substitute material for asbestos, but the fibrous alkali metal titanate currently available has a small aspect ratio compared to asbestos and is sufficiently suitable for practical use as a substitute for asbestos. The current situation is that it has not been completed.

Japanese Examined Patent Publication No. 42-27264 has hydrous titania as a titanium source,
Anatase TiO ₂ , TiO ₂ products in a commercial sulfate process for producing pigments, electronic powders or catalysts, well refined anatase pigments, ground rutile ore and commercial ilmenite are disclosed. . Also disclosed are alkali metal hydroxides and alkali metal carbonates as basic oxygen-containing alkali metal compounds. JP-B-42-27264 is for synthesizing 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 having a diameter of 0.005.
200-850 to produce a rich colloidal form with particle size ~ 0.1 micron and length at least 10 times the diameter
Baking at ℃, the diameter is 0.1 ~ 0.6 microns and the length is 10 ~
When producing a pigment-rich product with 100 times the particle size, it should be fired at 850 to 975 ℃, and an insulating type with a particle size of 0.6 to 3 microns and a length of 100 to 1000 times the particle size. It is described that the desired fibrous alkali metal titanate can be obtained by firing at 975 to 1150 ° C. when producing a rich product. Also disclosed is a manufacturing method in which an alkali metal halide is added to a non-liquid mixture of raw materials and then the mixture is fired.

However, it is difficult to separate the target substance that has grown as long fibers during firing, and due to the breaking of the fibers in the defibration process, the fiber length of the obtained fibrous alkali metal titanate is substantially 10 to 10.
The thickness was 20 μm and the aspect ratio was around 50, which was not sufficiently satisfactory, and the industrial application was extremely limited.

(Problems to be Solved by the Invention) An object of the present invention is to provide a long fibrous alkali metal titanate salt which can be easily separated from a fibrous nodule formed by firing and which prevents fiber breakage in a defibration process. To provide a manufacturing method.

Another object of the present invention is to provide a method for producing a long fiber-shaped alkali metal titanate salt having a large aspect ratio and a large mechanical strength such as bending strength and tensile strength.

(Means for Solving Problems) In the present invention, a mixture of a titanium source compound, an oxygen-containing alkali metal compound and a minute amount of an oxygen-containing iron compound is heated to a firing temperature at a slow heating rate of 10 ° C./minute or less. About 900-1350
Fiber diameter characterized by firing in the temperature range of ℃ 0.4
~ 200μm, fiber length up to 20mm, aspect ratio 50 ~ 500
0 relates to a method for producing a long fibrous alkali metal titanate salt.

The titanium source compound of the present invention is a compound substantially containing TiO ₂ , and specific examples thereof include titanium oxide, rutile ore, titanium hydroxide wet cake, and hydrous titania. The particle shape is preferably fine particles as much as possible.
For example, in anatase type fine particles in titanium oxide, in rutile ore, the particles are crushed by colliding the particles at high speed,
So-called "jet crushed products" are preferred. A suitable particle size is in the range of 200 to 425 mesh.

The oxygen-containing alkali metal compound used in the present invention is
It is a compound that produces M ₂ O (M is an alkali metal), and examples thereof include oxides, hydroxides, carbonates, bicarbonates, oxalates, and nitrates of potassium, sodium, cesium, and rubidium. Examples of such compounds include K ₂ O, KO
H, K ₂ CO ₃ , KHCO ₃ , K ₂ C ₂ O ₄ , KNO ₃ , Na ₂ O, NaOH, Na ₂ CO ₃ , NaHCO ₃ , Na ₂ C ₂ O ₄ , NaNO ₃ , Cs ₂ O, CsOH, _{Cs 2 CO 3, CsHCO 3,} Cs 2 C 2 O 4, CsNO 3, Rb 2 O, RbOH, Rb 2 CO 3, RbHCO 3, Rb 2 C 2 O 4, etc. RbNO ₃ can be mentioned. Of these, alkali metal nitrates are particularly preferable.

Examples of the oxygen-containing iron compound in the present invention include iron nitrate, sulfate, chloride, oxide, hydroxide and the like.

The mixing ratio of the titanium source compound and the oxygen-containing alkali metal compound is 4.0 in terms of the molar ratio in terms of TiO ₂ / M ₂ O (M is an alkali metal).
A range of up to 2.2 is preferred. In addition, it is necessary to add a small amount of oxygen-containing iron compound, but the addition amount is Fe ₂ O ₃ / TiO ₂
It is preferable that the converted molar ratio does not exceed 0.4.

In the present invention, the titanium source compound, the oxygen-containing alkali metal compound and the oxygen-containing iron compound may be mixed at the same time,
Alternatively, the remaining components may be added to the mixture of the two and mixed. The respective raw materials may be mixed as they are, or may be used by adding water to form a slurry and spray-drying. Although the method for preparing the mixture of raw materials is not limited to the above, the raw material mixture obtained by spray-drying the slurry-like raw material has oxygen-containing alkali metal uniformly and finely adhered to the particle surface of the titanium source compound. It becomes a granulated body, and since this granulated body has extremely high reactivity, it is particularly preferable.

In the present invention, these mixed raw materials are fired at a temperature of about 900 to 1350 ° C. to obtain a long-fiber alkali metal titanate salt.

In the present invention, a fiber shape having a fiber diameter of 0.4 to 200 μm, a fiber length of up to 20 mm, and an aspect ratio of 50 to 5000 is shown. In the chemical formula, M ₂ O.nTiO ₂ (M is an alkali metal), n is 6
And the compounds of 8 and M ₂ Ti ₈ O ₁₆ and compounds containing these titanium atoms partially replaced with iron atoms are obtained.

In the case of alkali hexatitanate, the addition amount of iron is preferably 0.17 or less in terms of Fe ₂ O ₃ / TiO ₂ molar ratio. The calcination can be carried out in a relatively wide temperature range, but is preferably carried out in the range of 1000 to 1250 ° C, preferably around 1150 ° C.

In the case of alkali octatitanate, the following two types of compounds represented by the general chemical formula MxTi ₈ -xFexO ₁₆ (0 <x ≦ 4) are obtained depending on the amount of iron added. That is, the amount of iron added is Fe
_When the molar ratio of ₂ O ₃ / TiO ₂ is in the range of 0.17 to 0.4, the firing temperature is in the range of 900 to 1200 ° C., preferably by firing at 1150 ° C. or less, a compound having a layered crystal structure can be obtained. . Then, the addition amount of iron is 0 in terms of Fe ₂ O ₃ / TiO ₂ conversion molar ratio.
In the range of 05 to 0.17, a compound having a tunnel structure can be obtained by treating at a firing temperature of 1150 to 1350 ° C, preferably 1220 ° C or higher. This is a compound known by the mineral name bridelite. The relationship between the chemical composition of the product and the reaction temperature is schematically shown in FIG.

In order to obtain an alkali metal titanate crystal in which fibers are sufficiently grown, it is preferable to gently raise the temperature to a predetermined firing temperature. The temperature raising process does not necessarily have to be a constant rate and continuous operation, but it is usually desirable to perform it at a rate of 6 ° C / min to 10 ° C / min. The firing time is usually about 45 minutes to 20
Predetermined reaction conditions can be satisfied if time is taken. After the reaction for a certain period of time, slow cooling is not particularly required. No significant difference is observed in the size of the fibrous crystals due to the rapid cooling. Since the heating rate has a large effect on the size of fibrous crystals, careful control is especially important at temperatures above 600 ° C.

Although the details of the reason are not clear, it is considered that, for example, the oxygen-containing alkali metal compound undergoes thermal decomposition during firing, and a gas such as the generated gas brings about a fiber shape that is easily disintegrated. Furthermore, it is considered that the oxygen-containing iron compound added in a small amount is involved in nucleation and promotes the growth of fiber-shaped crystals.

The crystalline fibrous alkali metal titanate salt produced by the above reaction is a nodule rich in fibrous material and acicularly grown from the surface thereof. Since this nodule contains a large amount of water-soluble alkali metal compound, the defibration step includes a method in which the above-generated fibrous substance is put into cold water or hot water and is performed by a disper stirring method or the like. In this case, it is preferable that the nodule is left in cold water or hot water for 1 hour or more so that it becomes sufficiently compatible with water. As the disintegrator, various known disintegrators can be used. After thoroughly defibrating and separating the dispersion liquid, it is washed with water. The alkali titanate fiber obtained by drying is a long fiber having a high aspect ratio without deteriorating the crystal shape by the defibration treatment.

(Examples) Examples will be described in detail below.

Example 1 3.9 commercially available reagent titanium oxide (anatase type) and the molar ratio of each TiO ₂ / K ₂ O potassium nitrate and ferric nitrate and Fe ₂ O ₃
Weigh so that the molar ratio of / TiO ₂ is 0.012, and mechanically grind and mix for a sufficient time. Next, this raw material powder was filled in an alumina crucible and placed in a heating furnace. The temperature rising rate was 10 ° C./minute, and the temperature was maintained at 1200 ° C. for 10 hours. afterwards,
The temperature was gradually cooled to about 900 ° C at a temperature decreasing rate of 10 ° C / min, and the heating power was turned off. In the crucible taken out of the furnace, pale yellow needle-like crystals like chestnut shells had grown. It was found from observations with a stereomicroscope and a scanning electron microscope that many of these crystals have a diameter of 3 to 4 μm, a length of 4 to 6 mm, and an aspect ratio of up to 1000. As a result of powder X-ray diffraction and chemical analysis, it was revealed that this crystal was potassium hexatitanate containing a trace amount of iron. The results of differential thermal analysis suggested that this result had an exothermic peak at 1320 ° C and decomposed and melted in air.

Example 2 The starting material was prepared in the same manner as in Example 1, and about 0.5 g of distilled water was added thereto. Then, a firing process was performed under the same conditions as in Example 1. The situation of the obtained product was almost the same as in Example 1, but the length of the needle-like crystals grown on the surface of the fibrous nodule was 5 to 7 mm, which was slightly longer than that in Example 1. Was there. The aspect ratio of the potassium hexatitanate fiber was in the same range as in Example 1.

Example 3 Titanium hydroxide, potassium nitrate and ferric oxide were each added to TiO ₂
Weigh so that the molar ratio of / K ₂ O is 3.6 and the molar ratio of Fe ₂ O ₃ / TiO ₂ is 0.052, and perform sufficient mechanical mixing. This was filled in an alumina crucible and placed in a heating furnace as in Example 1. The temperature rising rate was 5 ° C./min, and the temperature was maintained at 1200 ° C. for 12 hours. Immediately thereafter, the heating power source was turned off and a rapid cooling operation was performed to complete the reaction. 5 to 8 mm for the crucible taken out of the furnace
Light yellow needle-like crystals of length had grown on the surface of the fibrous nodules. The fibrous product in the nodule was obtained by immersing it in water for one day and night, defibrating it with a disper stirrer, separating, washing with water and drying. It was observed that all of these crystals had an aspect ratio of 700-1500.

From the results of X-ray diffraction and chemical analysis, these are 1.2 mol%
It was clarified to be potassium hexatitanate containing iron.

Example 4 Titanium oxide, cesium nitrate and ferric nitrate were each added to TiO ₂ / C.
Weigh so that the molar ratio of s ₂ O is 2.75 and the molar ratio of Fe ₂ O ₃ / TiO ₂ is 0.23, and mix sufficiently mechanically. This was filled in an alumina crucible and placed in a heating furnace as in Example 1. The temperature rising rate was 10 ° C./min, and the temperature was maintained at 1050 ° C. for 6 hours. Immediately thereafter, the heating power source was turned off to perform a rapid cooling operation to stop the reaction. In the crucible taken out of the furnace, fibrous crystals were attached to the wall in the form of lumps. The fibrous product in the nodule was roughly crushed and immersed in water, and then allowed to stand in a warming bath for 2 hours and dried separately. Next, this was defibrated using a jet crushing method [Pneumatic Japan Industrial Co., Ltd., PJM-100 type] to obtain fibrous crystals. Each of these crystals was cesium octatitanate having a length of 1.5 to 2 mm and an aspect ratio of 500 to 1250.

Example 5 Titanium oxide (anatase type), potassium nitrate and ferric nitrate were weighed so that the molar ratio of TiO ₂ / K ₂ O was 3.2 and the molar ratio of Fe ₂ O ₃ / TiO ₂ was 0.125, respectively, and sufficient Perform mechanical grinding and mixing for hours. Next, this raw material powder was filled in an alumina crucible and placed in a heating furnace. Temperature rising rate is 7 ° C /
Minutes, and kept at 1270 ° C. for 15 hours. After that, the temperature was gradually cooled to 1000 ° C. at a temperature decreasing rate of 20 ° C./min, and the heating power source was turned off. In the crucible taken out of the furnace, the average fiber diameter is 40-120μ.
m, the average fiber length was 6 to 15 mm, and brown crystals having an aspect ratio of up to 300 were observed. As a result of powder X-ray diffraction and chemical analysis, this crystal was found to have a briderite structure.
It was revealed to be potassium octatitanate containing mol% iron.

(Effect of the invention) According to the method of the present invention, the produced fiber is remarkably longer than the known fiber length, has a large aspect ratio and strength, and is easily separated from the fibrous nodule. The effect is obtained.

[Brief description of drawings]

Fig. 1 shows the product obtained under the condition that the molar ratio of TiO ₂ / M ₂ O (M is an alkali metal potassium) is fixed to 4 in the starting material, the reaction temperature and the starting material Fe ₂ O ₃ / TiO _2. The relationship with the molar ratio of ₂ is schematically shown.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayoshi Suzue 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture, Tokushima Plant, Otsuka Chemical Co., Ltd. (56) Reference JP-A-52-37832 (JP, A)

Claims (4)

[Claims] 1. A mixture of a titanium source compound, an oxygen-containing alkali metal compound, and a minute amount of an oxygen-containing iron compound is heated to a firing temperature at a slow heating rate of 10 ° C./min or less to about 900-1.
Fiber diameter characterized by firing in the temperature range of 350 ℃
0.4 ~ 200μm, fiber length up to 20mm, aspect ratio 50 ~
5,000 production methods of long-fiber alkali metal titanate. 2. The mixing ratio of the titanium source compound and the oxygen-containing alkali metal compound is 4.0 to 2.2 in terms of the molar ratio of TiO ₂ / M ₂ O (M represents an alkali metal), and the addition ratio of the oxygen-containing iron compound is Fe ₂ O
_The method according to claim 1, wherein the molar ratio of ₃ / TiO ₂ does not exceed 0.4. 3. The method according to claim 1, wherein the oxygen-containing alkali metal compound is an alkali metal nitrate. 4. The method according to claim 1, wherein the oxygen-containing iron compound is iron nitrate, sulfate, chloride, oxide or hydroxide.