JPH08209455A - Potassium titanate fiber and its production - Google Patents

Abstract

PURPOSE: To produce a potassium titanate fiber having suitable fiber shapes and physical properties useful as a composite reinforced material, an abrasion material, a filter material, etc., and to provide a method for producing the fiber in a simple process and enabling the easy adjustment of the physical properties. CONSTITUTION: This potassium titanate fiber has a composition containing 0.1-10wt.% of Al2 O3 and/or SiO2 and fiber shapes of an average fiber diameter of 0.2-2μm and an average fiber length of 5-30μm. Further, the fiber preferably has a nitrogen-absorbing specific surface area of 1-30m<2> /g and a bulk specific gravity (a tap density) of 0.05-0.5g/cc. The fiber is produced by compounding a mixture of (a) titanium oxide and (b) potassium oxide and/or a potassium compound producing potassium oxide by heating (a molar ratio in terms of TiO2 /K2 O: 2.0-8.0) as the main component with (c) metallic titanium [0.1-5wt.% based on the component (a)], and (d) alumina and/or (e) silica [0.1-10wt.% based on the component (a)] followed by baking at a temperature in the range of 900-1200 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a potassium titanate fiber used as a composite reinforcing material for plastics and light metals, a friction material, a filtering material and the like, and a method for producing the same, more specifically, a specific amount of alumina and / or silica. The present invention relates to a potassium titanate fiber having a specific fiber shape and a method for producing a potassium titanate fiber having an arbitrary fiber property.

[0002]

2. Description of the Prior Art Potassium titanate fibers are currently used as composite reinforcing materials for plastics and light metals, friction materials, filtering materials and the like. The physical properties required for the potassium titanate fiber vary depending on the application to which it is applied, but generally, the aspect ratio, which is the ratio of the fiber diameter to the fiber length, is high, and the reaction with the plastic or light metal that serves as the matrix. It is required that the compound be a stable compound with little property and be inexpensive.

Conventionally, various methods such as a firing method, a flux method, a melting method, a hydrothermal method, and a melt method have been known as means for producing potassium titanate fibers. Among them, the firing method is
The flux method and the melt method are considered to be industrially advantageous manufacturing techniques. The flux method is a method in which a mixture of potassium carbonate and titanium dioxide is used as a starting material, and a melting material (flux) such as potassium chloride or potassium fluoride is added to this to react them. The resulting potassium titanate fibers are thin and long. Although it has the advantage that the yield of single fiber crystals is high as well as having a fiber shape with excellent aspect properties, the economical problem that the manufacturing cost becomes high by using an expensive melting material, and potassium chloride and There are drawbacks such as the generation of harmful and highly corrosive gas containing chlorine and fluorine by potassium fluoride, the need for expensive equipment for recovering the melting material, and the complicated process. The melt method is a process in which a mixture of potassium carbonate and titanium dioxide is heated to 1100 ° C. or higher and melted, and then rapidly cooled and solidified. Although the obtained nodules are extremely rich in fiber, their composition is potassium dititanate fiber K ₂ Ti ₂ O ₅ ), which is an amorphous fiber having a large fiber diameter, is weak in strength and has a drawback that the field of use is limited as it is.

On the other hand, the firing method is a relatively inexpensive raw material,
For example, a method of using rutile sand or anatase sand which is a raw material ore or an upgrade ore of ilmenite as a titanium-based raw material instead of high-purity titanium dioxide (Japanese Patent Laid-Open No. 60-34617) has been proposed. It has attracted attention as a method for producing potassium titanate fiber. However, according to this method, although fibers having stable needle-like crystals can be produced, there is a problem in that the application is limited because the fibers have many variations in shape.

As a method for improving the firing method which solves the above problems, Japanese Patent Laid-Open No. 62-256799 discloses a mixture of titanium oxide-containing ore and a potassium compound, titanium powder and / or titanium hydride powder and alcohol. It discloses a method of obtaining potassium titanate fibers having a regular fiber shape by heating and firing a composition in which the compounds are added and mixed.

[0006]

Recently, as the applications of potassium titanate fibers have expanded, fibers such as the fiber shape represented by the aspect ratio, the bulk specific gravity, the specific surface area, etc. in each application field can be used. There is a stricter demand for higher quality in terms of physical properties, such as those with a high aspect ratio for plastic reinforcements, and those with a high bulk specific gravity and specific surface area for filtering and friction materials. It is required to provide individual physical properties most suitable for the purpose. Therefore, in order to meet the above requirements at a low production cost, it is necessary to develop a manufacturing technique capable of easily adjusting the physical properties without using expensive equipment and complicated steps.

As a result of intensive studies to solve the above-mentioned problems, the present inventors set the TiO ₂ / K ₂ O conversion molar ratio of titanium oxide and potassium carbonate, which are the main raw materials, to a specific range, and mixed this mixture. When a composition in which metallic titanium powder and an alumina component and / or a silica component are added and mixed is fired, in addition to the fiber shape such as fiber diameter and fiber length, bulk specific gravity (tap density) and nitrogen adsorption ratio surface area (N ₂ SA) It was confirmed that the above can be easily adjusted to desired physical properties within a specific range.

The present invention was developed on the basis of such findings, and an object thereof is to provide a potassium titanate fiber having a physical property range suitable for applications such as a composite reinforcing material, a friction material or a filtering material. Another object of the present invention is to provide a method for producing a potassium titanate fiber capable of adjusting a desired fiber shape, bulk specific gravity (tap density) and nitrogen adsorption specific surface area within the above-mentioned physical property ranges.

[0009]

The potassium titanate fiber according to the present invention for attaining the above-mentioned object comprises Al ₂ O ₃
And / or has a composition containing 0.1 to 10% by weight of SiO ₂ , an average fiber diameter of 0.2 to 2 μm and an average fiber length of 5
The main feature of the composition is to have a fiber shape of ˜30 μm, and the nitrogen adsorption specific surface area (N ₂ SA) is preferably 1 to 30.
m ² / g, and further has a bulk density (tap density) of 0.05 to 0.
It is an additional requirement to have the physical properties of 5g / cc.

The main physical characteristic of the potassium titanate fiber according to the present invention is a composition containing 0.1 to 10% by weight of Al ₂ O ₃ and / or SiO _2. An average fiber diameter of 0.2 to
It has a fiber shape of 2 μm and an average fiber length of 5 to 30 μm, and has a wide range of nitrogen adsorption specific surface area (N ₂ SA) of 1 to 30 m ² / g and bulk specific gravity (tap density) of 0.05 to 0.5 g / cc. Physical properties are provided.

The potassium titanate fibers having the above-mentioned physical properties are (a) titanium oxide (TiO ₂ ) and (b) potassium oxide (K ₂ O).
And / or a potassium compound that produces potassium oxide by heating is used as a main raw material, and (c) metallic titanium powder (T
i), (d) Alumina (Al ₂ O ₃ ) or an aluminum compound that produces alumina by heating, and / or (e) Silica (SiO ₂ ) or a silicon compound that produces silica by heating is added and mixed, and then 900 It is manufactured by a method of firing in a temperature range of ~ 1200 ° C for 0.5 to 10 hours.

As the titanium oxide (TiO ₂ ) constituting the main raw material, any one or more of titanium hydroxide, anatase titanium dioxide, rutile titanium dioxide, natural rutile ore and upgraded ilmenite ore can be used. And (b) potassium oxide (K
₂ O) and / or potassium compounds that generate potassium oxide by heating include K ₂ O, KOH, and K ₂ CO ₃
Alternatively KNO ₃ or a mixture of two or more of these is used. For the metal titanium powder (Ti) to be added and mixed with these main raw materials, it is preferable to use an undermesh product of titanium sponge obtained in the refining process of metal titanium from the viewpoint of cost, but use titanium hydride powder or the like. You can also

As the (d) alumina (Al ₂ O ₃ ), generally commercially available alumina powder can be appropriately used. However, instead of the alumina powder, it is also possible to use an aluminum compound such as aluminum hydroxide [Al (OH) ₃ ] that produces alumina by heating or a metal aluminum powder. (e) As the silica (SiO ₂ ) component, it is also possible to use a silicon compound such as silicon hydroxide [Si (OH) ₄ ] that produces silica by heating or a metal silicon powder, but in view of cost, white carbon is used. Those having a SiO ₂ content of about 95% by weight are preferably used.

The mixing composition of the raw material components is such that the mixing ratio of the component (a) and the component (b) is 2.0 to TiO ₂ / K ₂ O conversion molar ratio.
The amount of component (c) added to component (a) is 0.1 to 5% by weight, and the amount of component (d) and / or component (e) added is 0.1 to 10% by weight. Set to each. When the mixing ratio of these is out of the above range, the desired A
0.1 to 10% by weight of l ₂ O ₃ and / or SiO ₂
Has a composition containing and an average fiber diameter of 0.2 to 2 μm,
A fiber shape with an average fiber length of 5 to 30 μm was not obtained, and the nitrogen adsorption specific surface area (N ₂ SA) was 1 to 30 m ² / g and the bulk specific gravity (tap density) was 0.05 to 0.5 g / cc. It becomes impossible to obtain the potassium titanate fiber provided with.

The mixture obtained by adding the components (c) to (e) to the component (a) and the component (b) is subjected to a firing treatment in the temperature range of 900 to 1200 ° C. to be converted into potassium titanate fibers. If the firing temperature is lower than 900 ° C, potassium titanate fibers are not smoothly produced, and if the heating temperature is higher than 1200 ° C, the production of potassium titanate fibers having the desired fiber shape and physical properties is hindered and the production cost is reduced. Is not preferable because it increases the

In the above method, the addition amount of the component (c), the component (d) and / or the component (e) is adjusted to adjust the molar ratio of the component (a) and the component (b) in terms of TiO ₂ / K ₂ O. If the calcination treatment is performed at the same temperature and time while maintaining a constant value, the fiber shape, bulk specific gravity (tap density), and nitrogen adsorption specific surface area (N ₂ SA) can be arbitrarily controlled within the above-mentioned physical property range. it can.

In particular, the TiO as the component (a) and the component (b)
_The mixing molar ratio in terms of ₂ / K ₂ O is within the range of 2.0 to 8.0, and the component (c) is 0.1 to 5% by weight with respect to the component (a).
The mixture containing 0.1 to 10% by weight of the component (d) was added to 9
By setting the conditions for firing for 0.5 to 10 hours in the temperature range of 00 to 1200 ° C., the average fiber diameter is 0.2 to 0.7 μm.
It is possible to give a high aspect property of (a)
Similarly, the TiO ₂ / K ₂ O conversion molar ratio of the component and the component (b) is in the range of 2.0 to 8.0, and the component (c) is 0.1 to 5% by weight relative to the component (a). And (e) component 0.1 to 1
By firing the mixture containing 0% by weight in the temperature range of 900 to 1200 ° C. for 0.5 to 10 hours, it becomes possible to obtain potassium titanate fibers in the form of very thick fibers having an average fiber diameter of 0.8 μm or more. .

[0018]

The potassium titanate fiber provided by the present invention contains Al ₂ O ₃ and / or SiO _{2 in an amount} of 0.1-10.
It has a fiber shape of 0.2 to 2 μm in average fiber length and 5 to 30 μm in average fiber length, which is suitable for various applications due to its unique component composition, and has a bulk specific gravity (tap density). ) A wide range of physical properties such as 0.05 to 0.5 g / cc and a nitrogen adsorption specific surface area (N ₂ SA) of 1 to 30 m ² / g are provided.

Further, according to the manufacturing method of the present invention, the mixing ratio of the component (a) and the component (b), which are the main raw materials, is TiO ₂ / K.
Adjust the molar ratio of ₂ O in the range of 2.0 to 8.0,
On the other hand, it is possible to control the desired average fiber shape, bulk specific gravity, and nitrogen adsorption specific surface area within the above-mentioned physical properties by subjecting the additive mixture in which the components (c) to (e) are appropriately selected to a firing treatment. At this time, the component (c) functions as a reaction accelerator for efficiently producing potassium titanate fibers when mixed with the main raw material and fired, and the component (d) and the component (e) are used alone or When used together, it acts like a reaction modifier. Therefore, by appropriately increasing / decreasing the components (c) to (e) within the specified addition and mixing range, the mixing ratio of the main raw material components is not changed and the baking conditions are constant (baking temperature 900 to 1200 ° C). , Firing time 0.5
The desired physical properties are easily imparted within 10 hours). On the other hand, the fiber surface is coated with alumina and / or silica, which contributes to the improvement of the specific surface area and the provision of excellent weather resistance. Combined with such actions, it becomes possible to industrially produce potassium titanate fiber having a fiber shape and physical properties suitable for each purpose of use by simply setting the conditions.

[0020]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples. However, the scope of the invention is not limited to these examples.

Example 1 Commercially available anatase type titanium oxide [manufactured by Teika Co., Ltd., JA-
1] 6 mol of 1.9 mol of granular potassium carbonate (manufactured by Asahi Glass Co., Ltd.) was used as a main raw material, and metallic titanium powder was added as an additive to the main raw material in an amount of 3% by weight with respect to titanium oxide and Al. ₂ O ₃ powder was added in an amount ratio of 3% by weight to titanium oxide, pre-blended in a vinyl bag, and then secondary pulverized and mixed with a hammer mill ("Pulperizer" manufactured by Hosokawa Micron Corp.). The mixed raw material was placed in a nickel crucible, set in an electric furnace, and fired at 1070 ° C. for 2 hours. Then, the fired product is placed in water in a plastic container and immersed for 1 hour, and then a colloid mill [Special Kika Kogyo Co., Ltd.
Manufactured by "My Colloider"]. The obtained slurry was classified, and the fine particle side was adjusted with sulfuric acid to adjust the amount of potassium to pH 7.5. The slurry is filtered, 6
Heat treatment was performed at a temperature of 00 ° C. for 1 hour to disperse and classify the heat treated product.

The potassium titanate fiber thus obtained has an extremely regular fiber shape as shown in the electron microscope photograph (SEM photograph) shown in FIG. 1, and is a needle-like single crystal potassium octatitanate fiber. Was confirmed. When the physical properties of the fiber were measured, the results shown in Table 1 were obtained. For the measurement of each physical property, the average fiber length was calculated from the data obtained by displaying an image of an optical microscope on a television monitor and analyzing the image with a computer. The average fiber diameter was measured by SEM of dispersedly sampled fibers.
Each fiber was measured with a magnifying glass and the magnification was converted. The standard deviation was calculated from the data measured with a magnifying glass based on the SEM photograph taken to measure the average fiber diameter. The nitrogen adsorption specific surface area was measured by the BET multipoint continuous flow method [Yuasa Ionics Co., Ltd., Cantersoap type, QS-17].

Example 2 To the same main raw material as in Example 1, 3% by weight of metallic titanium powder and 3% by weight of SiO ₂ powder were added as additives, respectively, to titanium oxide. The subsequent operating conditions were the same as in Example 1 to produce potassium titanate fiber. The obtained potassium titanate fiber has a regular fiber shape as shown in the electron micrograph of FIG.
It was confirmed to be potassium titanate fiber. The results of measuring the physical properties of the fibers are also shown in Table 1.

Example 3 With respect to the same main raw material as in Example 1, metal titanium powder as an additive was added in an amount of 3% by weight based on titanium oxide, and SiO ₂ powder 1.
5% by weight and 1.5% by weight of Al ₂ O ₃ powder were added respectively. The subsequent operating conditions were the same as in Example 1 to produce potassium titanate fiber. The obtained potassium titanate fiber had a regular fiber shape as shown in the electron micrograph of FIG. 3, and it was confirmed to be octapotassium titanate fiber. The results of measuring the physical properties of the fiber are shown in Table 1.
It was also published in.

Example 4 A potassium titanate fiber was produced under the same operating conditions as in Example 1, except that the firing temperature was changed to 1040 ° C. and the firing time was changed to 3 hours. The obtained potassium titanate fiber was potassium octatitanate fiber, and the fiber physical properties were as listed in Table 1.

Example 5 A potassium titanate fiber was produced under the same operating conditions as in Example 2, except that the firing temperature was changed to 1040 ° C. and the firing time was changed to 3 hours. The obtained potassium titanate fiber was potassium octatitanate fiber, and the fiber physical properties were as listed in Table 1.

Example 6 A potassium titanate fiber was produced under the same operating conditions as in Example 3, except that the firing temperature was changed to 1040 ° C. and the firing time was changed to 3 hours. The obtained potassium titanate fiber was potassium octatitanate fiber, and the fiber physical properties were as listed in Table 1.

Example 7 Potassium titanate fibers were produced under the same operating conditions as in Example 4, except that the firing temperature was changed to 1100 ° C. The obtained potassium titanate fiber was potassium octatitanate fiber, and the fiber physical properties were as listed in Table 1.

Comparative Example 1 To the same main raw material as in Example 1, 3 wt% of metallic titanium powder alone as an additive was added and mixed with titanium oxide.
The subsequent operating conditions were the same as in Example 1 to produce potassium titanate fiber. The obtained potassium titanate fiber is
As shown in the electron micrograph of FIG. 4, the fiber had a nonuniform fiber shape. In addition, as also shown in Table 1, the fiber physical properties were inferior to those of the examples.

[0030]

[Table 1] [Table Note] * The standard deviation was calculated from the data measured with a magnifying glass from the SEM photograph of the average fiber diameter.

As is clear from the results shown in Table 1, according to the examples satisfying the requirements of the present invention, the firing conditions were set to a temperature of 900-1.
It is possible to adjust the fiber shape and properties such as bulk specific gravity and nitrogen adsorption specific surface area within a desired range by selecting the type of additive component and the ratio of addition amount within the range of 200 ° C. and firing time of 0.5 to 10 hours. Is recognized. On the other hand, in Comparative Example 1 in which the additive component was only metallic titanium powder, the fiber shape was uneven and the bulk specific gravity was extremely high.

[0032]

As described above, according to the present invention, potassium titanate fiber having a fiber shape and physical properties suitable for a composite reinforcing material, a friction material and a filtering material for plastics and light metals, and a simple operating means for the fiber. Thus, it is possible to provide a production method in which desired physical properties can be adjusted.
Furthermore, since the potassium titanate fiber produced as an incidental effect is in a composite form in which the surface is coated with alumina or / and silica, excellent weather resistance can be imparted. Therefore, it is possible to expand the application.

[Brief description of drawings]

FIG. 1 is an electron microscope enlarged photograph showing the fiber shape of the potassium titanate fiber obtained in Example 1 (magnification:
3000 times).

FIG. 2 is an electron microscope enlarged photograph showing the fiber shape of the potassium titanate fiber obtained in Example 2 (magnification:
3000 times).

FIG. 3 is an electron microscope enlarged photograph showing the fiber shape of the potassium titanate fiber obtained in Example 3 (magnification:
3000 times).

FIG. 4 is an electron microscope enlarged photograph showing the fiber shape of the potassium titanate fiber obtained in Comparative Example 1 (magnification:
3000 times).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasumasa Tanaka 3-3-5 Chigasaki, Chigasaki City, Kanagawa Japan Whisker Company Limited

Claims (8)

[Claims] 1. A fiber having a composition containing 0.1 to 10% by weight of Al ₂ O ₃ and / or SiO ₂ and having a fiber shape with an average fiber diameter of 0.2 to 2 μm and an average fiber length of 5 to 30 μm. A potassium titanate fiber characterized by: 2. A nitrogen adsorption specific surface area (N ₂ SA) of 1 to 30 m ²
The potassium titanate fiber according to claim 1, which is / g. 3. The bulk specific gravity (tap density) is 0.05 to
The potassium titanate fiber according to claim 1, which has an amount of 0.5 g / cc. 4. A main raw material comprising (a) titanium oxide (TiO ₂ ) and (b) potassium oxide (K ₂ O) and / or a potassium compound which produces potassium oxide by heating, and (c) metallic titanium powder (Ti), (d) alumina (Al ₂ O ₃ ) or an aluminum compound that produces alumina by heating, and / or (e) silica (SiO ₂ ) or after adding and mixing a silicon compound that produces silica by heating, 900-1200
A method for producing a potassium titanate fiber, which comprises firing in a temperature range of ° C. 5. The mixing ratio of the component (a) and the component (b) is TiO ₂
/ K ₂ O converted molar ratio is in the range of 2.0 to 8.0, (a)
0.1 to 5% by weight of the component (c) is added to the component,
The addition amount of the component (d) and / or the component (e) is 0.1 to 1
The method for producing potassium titanate fiber according to claim 4, wherein the amount is set to 0% by weight. 6. The method according to claim 4 or 5, wherein (c)
TiO ₂ / K of the component (a) and the component (b) by adjusting the addition amount of the component, the component (d) and / or the component (e)
_A feature that the fiber shape, bulk specific gravity (tap density) and nitrogen adsorption specific surface area (N ₂ SA) are arbitrarily controlled without changing the ₂ O conversion molar ratio and without changing the firing temperature and firing time. And a method for producing potassium titanate fiber. 7. The method according to claim 4 or 5, wherein (a)
The mixing molar ratio of TiO ₂ / K ₂ O conversion of the component and the component (b) is within the range of 2.0 to 8.0, and the component (a) is mixed with the component (c).
A high aspect ratio, characterized in that the mixture containing 0.1 to 5% by weight of the component and 0.1 to 10% by weight of the component (d) is fired in the temperature range of 900 to 1200 ° C. for 0.5 to 10 hours. Showing a method for producing potassium titanate fiber. 8. The method according to claim 4 or 5, wherein (a)
The mixing molar ratio of TiO ₂ / K ₂ O conversion of the component and the component (b) is within the range of 2.0 to 8.0, and the component (a) is mixed with the component (c).
Extra-thick fiber shape characterized in that a mixture containing 0.1 to 5% by weight of the component and 0.1 to 10% by weight of the component (e) is fired in the temperature range of 900 to 1200 ° C. for 0.5 to 10 hours. 1. A method for producing potassium titanate fiber.