JPH10212625A - Production of potassium titanate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make waste liquid treatment unnecessary and increase fiber yield by eliminating potassium ion elution process in production of potassium titanate by melting method. SOLUTION: A mixture of titanium oxide with potassium oxide (having 1.5-2.5 molar ratio of TiO2 /K2 ) is heat-melted and cooled and the resultant potassium titanate fiber mass-like material is immersed in water. The fiber mass is fibrillated in water and titanium dititanate powder is added (in an amount controlled according to composition of the objective product fiber) and uniformly mixed. The mixture is recovered from the liquid and dehydrated and dried and subjected to baking treatment (at 900-1,200 deg.C) and potassium titanate fiber represented by the formula K2 Tin O2n+1 [(n) is 4-6] is deposited from the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing potassium titanate fibers useful as sliding members, paint fillers, reinforcing fibers of metals and plastics, and the like.

[0002]

2. Description of the Related Art Potassium titanate fiber has the general formula K ₂ T
i _n O _{2n +} is a synthetic inorganic fibers represented by _1, a variety of engineering applications in various fields have been tried as asbestos fibers alternate materials. Among them, potassium hexatitanate fiber (K ₂
Ti ₆ O ₁₃ ), potassium tetratitanate fiber (K ₂ Ti ₄ O)
₉ ) Due to its wear resistance and thermal stability, various proposals have been made regarding the practical use of base fibers for sliding members such as brake pads for automobiles, fillers for heat-resistant paint, and reinforcing fibers for plastics. It has been done. A melting method is known as an industrial production method of the potassium titanate fiber. The melting method uses titanium dioxide (TiO ₂ ) and potassium oxide (K
₂ O) (a compound that generates these oxides by heating) may be used as a raw material, and the TiO ₂ / K ₂ O
(1.5 to 2.5) a step of heating and melting the mixture prepared at a ratio of, a step of cooling the heated melt to obtain a lump (fiber lump) of potassium titanium dioxide fibers (K ₂ Ti ₂ O ₅ );
Dissolving the fiber mass with water, an acid aqueous solution or the like as a treatment liquid, eluting K ions in the fiber to convert the composition into a hydrated potassium titanate fiber having a predetermined chemical composition, and the hydrated titanic acid Through the step of baking (crystal structure conversion) the potassium fiber, a potassium titanate fiber as an object is obtained.

[0003]

The starting material is TiO ₂
/ K ₂ O (molar ratio) is adjusted to be about 2.
As shown in the K ₂ O-TiO ₂ phase diagram in FIG. 1, it is possible to achieve heat melting treatment in a low temperature range in the composition range, which suppresses the corrosion and erosion of the melting crucible and reduces the melting method. This is important in that it enables industrial production of potassium titanate fiber by the above method. However, the primary phase fiber produced by cooling the heated melt is potassium dititanate fiber K ₂ Ti ₂ O ₅ (TiO ₂ / K ₂ O molar ratio = 2),
For this reason, potassium hexatitanate fiber K ₂ Ti ₆ O ₁₃ (equivalent molar ratio = 6), potassium tetratitanate fiber K ₂ Ti ₄ O ₉ (equivalent molar ratio = 4) and the like are derived from the primary phase fiber. For this purpose, a K ion elution process (depotassium treatment) is required as a composition conversion process. Performing the K ion elution process inevitably lowers the fiber yield (product fiber yield based on the amount of raw material used), and involves a complicated process and a large cost burden for treating the waste liquid from the elution process. Is what you do. The present invention eliminates the disadvantages of the conventional K ion elution treatment and the waste liquid treatment associated therewith, such as the complicated and costly burden, while adopting the above-mentioned raw material composition for performing the heating and melting treatment at a low temperature range. And a method for producing a potassium titanate fiber capable of obtaining a high yield.

[0004]

According to the present invention, there is provided a method for producing a potassium titanate fiber comprising the steps of: mixing titanium dioxide or a titanium compound which becomes titanium dioxide by heating with potassium oxide or a potassium compound which becomes potassium oxide by heating;
A step of heating and melting the mixture blended so that the molar ratio of O ₂ / K ₂ O is 1.5 to 2.5, a step of cooling the heated melt to obtain a fiber mass made of potassium dititanate fibers,
The fiber mass is immersed in water to be defibrated, and titanium dioxide powder is added to the solution to obtain TiO ₂ / K ₂ O (molar ratio).
Is a step of forming a uniform mixture of potassium dititanate fiber and titanium dioxide powder, wherein the mixture is from 4 to 6, the mixture is recovered from the liquid, dehydrated and dried, and then subjected to a baking treatment,
Wherein: wherein, n = 4 to 6] K ₂ Ti _n O _{2n + 1} is characterized by comprising the step, to generate precipitate of potassium titanate fibers represented by.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not different from the conventional method in that the starting material is adjusted to have the same composition as that of the conventional method, so that potassium dititanate fiber is produced as the primary phase fiber.
The conversion process of the primary phase fiber into the chemical composition of the target fiber and the conversion process of the crystal structure are significantly different from the conventional method. That is, in the conventional method, K ions in the crystal are eluted (de-potassium) from the primary phase fiber dititanate K ₂ Ti ₂ O ₅ (molar ratio of TiO ₂ / K ₂ O = 2) to obtain the fiber composition ( TiO ₂ / K ₂ O molar ratio) is converted to a composition corresponding to the target fiber, whereas the present invention, on the contrary,
Titanium dioxide (TiO ₂ ) is added to and mixed with the primary phase fiber,
The mixture is given a chemical composition corresponding to the target fiber. In contrast to the conventional method, a target fiber is obtained by causing a crystal structure conversion by a baking treatment on the dekalized fiber (hydrated potassium titanate fiber).
A mixture of the primary phase fiber (potassium dititanate fiber) and titanium dioxide is subjected to a baking treatment, and a target fiber is precipitated as a reaction product.

As described above, in the present invention, K ions are not eluted from primary phase fibers (loss of fiber constituent components) unlike the conventional method, and the entire amount of potassium constituting the primary phase fibers is used as a constituent component of the target fiber. Therefore, the yield of the target fiber is increased accordingly. In addition, the conventional method of eluting K ions of the primary phase fiber requires updating the treatment liquid in accordance with a decrease in ion elution ability due to an increase in the concentration of K ions in the treatment liquid (water, acid aqueous solution, etc.). And the waste liquid treatment is required. On the other hand, the treatment liquid (water) in the present invention is a dispersion medium for performing the fibrillation of the fiber mass and the uniform mixing of the titanium dioxide powder, and does not require ion eluting ability. The treatment liquid does not need to be renewed, and can be used repeatedly over a long period of time, which makes it possible to effectively use the treatment liquid (water resources) and reduce the burden of waste liquid treatment.

Hereinafter, the present invention will be described in the order of steps.

[Raw material adjustment] Titanium dioxide (TiO)_Two) Is a purified you
Titanium sand, purified rutile sand, etc.
As halogen compounds, sulfates, nitrates, hydration
Use of objects and the like is also possible. Potassium oxide (K_TwoO)
Typically, potassium carbonate (K _TwoCO_Three) Is obtained industrially
Easy and suitable for use. In addition, hydroxide,
It is also possible to use halogen compounds, nitrates and the like. Origin
The composition of the ingredients is TiO_Two/ K_TwoO is 1.5 to 2.5
Adjustment to the range is, as described above, within this composition range.
And achieved melting treatment by heat treatment in a relatively low temperature range,
Efficient use of potassium dititanate fiber as primary phase fiber
This is because it can be generated.

[0008]

[Heat melting and cooling and solidification of the melt] The melting treatment of the starting material is achieved by heating and holding at a temperature of about 950 to 1100 ° C for an appropriate time, and then cooling the heat-melted product to form a mass of primary phase fibers. obtain. The fiber mass is a bundle of potassium dititanate fibers grown along the temperature gradient during the cooling and solidification process.

[0009]

[Disintegration of fiber mass and addition of titanium dioxide powder] When the fiber mass is put into water and held for an appropriate time, the bonds between the fibers are broken by swelling and cleavage, and the fibers are dispersed in the liquid. By adding a gentle stirring flow to the treatment liquid, defibration can be promoted. Titanium dioxide (purified anatase sand, purified rutile sand, etc.) is added to this liquid and mixed uniformly. The addition of the titanium dioxide powder may be performed simultaneously with the introduction of the fiber mass into the liquid. The amount of titanium dioxide powder added is
It is adjusted according to the composition of the target product potassium titanate fiber. That is, when the target fiber is potassium hexatitanate fiber [K ₂ Ti ₆ O ₁₃ ], the potassium dititanate fiber (K ₂ Ti ₂ O ₅ ) and the titanium dioxide (TiO ₂ ) added thereto are mixed. If the mixture has a TiO ₂ / K ₂ O molar ratio of about 6, and the target fiber is potassium tetratitanate fiber [K ₂ Ti ₄ O ₉ ], the TiO ₂
/ Adjust the amount of titanium dioxide powder to be added so that K ₂ O is 4. The treatment liquid (water) used in the above-mentioned fiber lump defibration and titanium dioxide powder suspension / mixing treatment contains various soluble substances eluted from the fiber lump, but the next fiber lump is defibrated as it is. And titanium dioxide powder can be repeatedly used as a treatment liquid for performing suspension mixing.

[0010]

[Baking treatment] A uniform mixture of potassium dititanate fiber and titanium dioxide powder is collected from the treatment liquid, dehydrated and dried, and subjected to a baking treatment. By the firing treatment, the potassium dititanate fiber reacts with the titanium dioxide particles, and the desired potassium titanate fiber is precipitated and formed. When the mixture to be calcined has a composition in which the molar ratio of titanium dioxide / potassium dititanate is about 6, the following formula [1]
In the case of a mixture in which potassium hexatitanate fiber [K ₂ Ti ₆ O ₁₃ ] is produced and the molar ratio is about 4, the potassium tetratitanate fiber [K ₂ Ti 6 ₄ O
₉ ] is generated. When the mixture has a composition in between these, a mixed phase fiber of potassium hexatitanate fiber and potassium tetratitanate fiber is obtained. The baking treatment is performed at a temperature of about 900 to 1200 ° C. for an appropriate time (about 1
~ 4Hr) is achieved by holding. _{K 2 Ti 2 O 5 + 4TiO} 2 → K 2 Ti 6 O 13 ... (1) _{K 2 Ti 2 O 5 + 2TiO} 2 → K 2 Ti 4 O 9 ... [2]

[0011]

【Example】

[1] Preparation of Starting Material Purified Anatase Powder (Purity: 99%) Industrial Potassium Carbonate Powder (Purity: 99.5%) Compounding Ratio: TiO ₂ / K ₂ O = 2.0 [2] Heat Melting and Cooling Solidification Put the starting material powder in a platinum crucible, at 1100 ° C for 1 hour
After heating and melting, the molten product is poured into a metal dish, and directional solidification is performed upward from the bottom of the dish to obtain a fiber mass made of potassium dititanate fiber.

[3] Fibrillation and Composition Adjustment The fiber mass is immersed in 4 times (weight) water (reuse the water used in the preceding fibrillation treatment) and defibrated in 4Hr. Titanium dioxide powder (purity: 99%) is added thereto, mixed uniformly, and then recovered from the liquid. The addition amount of the titanium dioxide powder is TiO ₂ / mixture with potassium dititanate fiber.
K ₂ O (molar ratio) was adjusted to 6. [4] Firing treatment After the recovered mixture is dehydrated and dried (110 ° C × 4 hours),
A baking treatment (1000 ° C. × 4 hours) is performed. The obtained fiber crystal structure (X-ray diffraction), fiber morphology (scanning electron microscope),
And fiber yield (weight ratio of product yield to total amount of starting material and titanium dioxide powder used for mixing treatment)
Is as follows. Fiber crystal: potassium hexatitanate fiber K ₂ Ti ₆ O ₁₃ fiber form: polycrystalline, fiber diameter about 10-50 μm, length about 5
0 to 300 μm Fiber yield: about 87%

[0013]

[Comparative example]

[1] Preparation of starting materials Same as in the example [2] Heat melting and cooling and solidification treatment Same as in the example [3] Fibrillation and composition adjustment Immerse fiber mass in 170 times (weight) water and defibrate At the same time, K ions are eluted and potassium dititanate fiber is
The composition was converted into a hydrated potassium titanate fiber of iO ₂ / K ₂ O (molar ratio) 6.

[4] Firing treatment Same as in the embodiment [dehydration drying (110 ° C × 4Hr) → firing treatment (1000 ° C × 4Hr).
The fiber form and fiber yield [weight ratio of product yield to starting material] are as follows. Fiber crystal: Potassium hexatitanate fiber K ₂ Ti ₆ O ₁₃ Fiber form: polycrystalline, fiber diameter about 20-50 μm, length about 1
00-300 μm Fiber yield: about 61%

[0015]

According to the method of the present invention, the target product fiber can be obtained in a high yield without the need for K ion elution (depotassium) treatment of the primary phase fiber. In addition, the treatment liquid used for the defibration of the primary phase fiber mass and the mixing treatment of titanium dioxide can be reused repeatedly, and by circulating in the system,
The complexity and the cost required for the conventional waste liquid treatment process are reduced, and environmental pollution due to the waste liquid is also avoided.

[Brief description of the drawings]

FIG. 1 is a TiO ₂ —K ₂ O system phase diagram.

Claims (1)

[Claims] 1. Titanium dioxide or a titanium compound which becomes titanium dioxide when heated, and potassium oxide or a potassium compound which becomes potassium oxide when heated, are mixed with TiO ₂
A step of heating and melting a mixture blended so that the molar ratio of / K ₂ O is 1.5 to 2.5; a step of cooling the heated melt to obtain a fiber mass made of potassium dititanate fibers; The lump is immersed in water for defibration, and titanium dioxide powder is added to the liquid to obtain TiO ₂ / K ₂ O (molar ratio).
Forming a uniform mixture of potassium dititanate fiber and titanium dioxide powder, wherein 4 to 6 is obtained. The above mixture is recovered from the liquid, dehydrated and dried, and then subjected to a baking treatment to obtain a formula: K ₂ Ti _n O _{2n + 1} wherein, n = 4 to 6]
A step of depositing and generating a potassium titanate fiber represented by
A method for producing a potassium titanate fiber, comprising: