JPS5930724A - Manufacture of fibrous potassium titanate - Google Patents

Abstract

PURPOSE:To manufacture filaments of a K2Ti4O9-K2Ti2O5 mixture without using a flux, by heating a mixed composition consisting of K2O and TiO2 is a specified ratio to a specified temp. to form K2Ti6O13 and a liq. phase mixed composition, slowly cooling the composition, and further cooling it. CONSTITUTION:A mixed composition consisting of K2O and TiO2 represented by a formula K2O.nTiO2 (2<n<3) or a mixture of starting materials for manufacturing the composition is heated and kept at 1,000-1,350 deg.C to form a solid phase K2Ti6O13 and a liq. phase mixed composition by decomposition and melting reactions. The composition is slowly cooled at <=70 deg.C/hr rate from said temp. to 900-950 deg.C, and by regulating the slow cooling rate, a mixtur of solid phase K2Ti4O9 with a liq. phase mixed composition is formed by an association reaction. K2Ti2O5 is then crystallized from the composition by cooling to manufacture fibrous potassium titanate made of a K2Ti4O9-K2Ti2O5 mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing a mixed fiber of potassium acid fiber and potassium titanium fiber.

Conventionally, methods for producing fibrous potassium titanate include the flux method, hydrothermal synthesis method, melt method, and sintering method, but the industrial method is the 7-lux method.

This method has the disadvantage of high cost due to the need for a recovery process.

The melt method can be used in the chemical field because the resulting fibers have a large fiber diameter and low strength, but there are problems with its use in fields that require physical strength.

Furthermore, although the firing method is simple to produce, it has the drawback that only short fibers can be obtained.

As a result of research on making long fibers of potassium titanate using the flux method, the inventor of S゛杢 discovered potassium molybdate and potassium tungstate as new 7 luxes that can be made into long fibers without pollution. 1
(See No. 031819). Furthermore, as a result of research to elucidate the fiber growth mechanism using the 7 lux, it was found that titanium oxide same phase and potassium oxide liquid phase were formed at high temperature, and when this was slowly cooled, tetratitanium acid force It was found that the flux has a catalytic effect and only a small amount of flux is needed. However, since we use 7 lacs, although it is a small amount,
Flux removal and recovery equipment is required, and a large amount of industrial water is also required, resulting in high production costs.

As a result of further research, we found that potassium oxide 1, represented by the general formula 20·nTiO2 (where n = 3 to 5),
Decomposition is carried out by removing the melt from 900°C to SO at a rate of 70°C/h or less using a mixed composition of titanium dioxide and titanium dioxide (hereinafter referred to as mixed composition) without using flux. By carrying out the melt-association reaction, we succeeded in obtaining single potassium titanate fibers and mixed fibers of potassium tetratitanate fibers and potassium nichimenate fibers or potassium hexatitanate fibers (Patent Application 1973-/63!).
ilr issue).

It has been found that when a smaller n is used, such as 2<n<J, a mixed fiber of potassium tetratitanate fiber and potassium nichimen fiber can be obtained in the same manner, and the present invention has been completed. The reaction formula is as follows (where n
shows J and lr as representative examples. ).

(Solid phase) (Liquid phase) f (K2Ti40.) +g (K2Ti2O5)
(4) (Solid phase) (Solid phase) (However, a + b, Or d + e r f
r g represents an arbitrary coefficient, n represents kokunkuko, and Ir. )2. The value of n in the liquid-solid phase changes depending on the temperature.

That is, 1, . 5) Due to the decomposition melting-association reaction in formula i, potassium tetratitanate and the liquid phase become predominant at high temperatures, the association reaction is promoted by slow cooling, and the potassium titanate fibers grow long. After slow cooling, the mixture is taken out into the atmosphere and rapidly cooled, and according to equation (4), most of the liquid phase of the mixed composition becomes crystals of potassium nititanate fibers.

Therefore, the final result is an aggregate of mixed-phase fibers of potassium tetratitanate fibers and potassium nichimenate fibers.The gist of the present invention is as follows.

A mixed composition of potassium oxide and titanium dioxide represented by
A mixed composition of potassium hexatitanate in the same phase and a liquid phase is generated by a decomposition-melting reaction by heating and maintaining at 0°C, and then slowly cooled from this temperature to qoo to q and to°C at a rate of 70°C/h or less. , a method for producing fibrous potassium titanate which forms a solid phase of potassium tetratitanate and a liquid phase through an association reaction by adjusting the slow cooling rate.

If the value of n in the general formula of the raw material in the present invention is 20·nTio□ is less than 2, harmonic melting will occur, and the decomposition melting-association reaction will not occur, making it impossible to achieve the purpose.

Further, when n is 3 or more, the fiber becomes a mixed phase fiber of potassium tetratitanate fiber alone or potassium hexatitanate fiber or potassium nithimenate fiber.

No potassium titanate fibers are produced and potassium tetratitanate fibers are obtained as longer fibers than in the case of n=3. This is because the liquid phase component increases as the value of n is larger than 2 and smaller than Hiro, and the liquid phase acts like 7 lux due to the association reaction.1. This is thought to be due to promoting the growth of potassium tetratitanate fibers.

Titanium compounds that further decompose to produce titanium dioxide can be used as well.

As the potassium oxide, potassium oxide or a mixture of seven or two of potassium carbonate, potassium bicarbonate, potassium hydroxide, potassium nitrate, etc., which are decomposed by heating to produce potassium oxide, can be used.

The above raw materials are expressed in the general formula 20・nTio2, where n is
Preferably//! The decomposition melt-association reaction is carried out by slow cooling from this temperature to OO~SO''C preferably for 7~70 hours at 0~i, zzo<0>C, preferably under tetratitanic acid.

By repeating this operation of heating, baking, holding, and slow cooling, the growth of potassium tetratitanate fibers can be improved. In this case, there is no problem even if the slow cooling rate is changed for each repetition or during slow cooling. However, since the potassium nititanate fibers are first crystallized from the liquid phase by rapid cooling after 900°C, the repetition of the decomposition-melting-association reaction is not related to the growth of potassium nitimenate;

After slow cooling from qoo to 5♂C, it is taken out into the atmosphere and allowed to cool. Slow cooling to room temperature may be used, but potassium tetratitanate fibers do not grow at low temperatures, so time is wasted.

What is obtained by cooling consists of a mixed phase of potassium tetratitanate fibers and potassium nititanate fibers, both of which have a layered structure. This is useful as a hot water and boiling ion adsorbent.

Example 1 Titanium oxide (TiO2) and potassium carbonate in a molar ratio of 20
．． Mixed in the ratio of r to /. Put this mixture 252 into a platinum crucible and heat it in an electric furnace. Raise the temperature to OC and leave it at q
Baked for an hour. Thereafter, it was slowly cooled to 950°C at a rate of 16°C/h.

Ruriho was taken out into the atmosphere and cooled to room temperature.

It was a lump consisting of a mixed phase with lime fibers.

This crucible was immersed in warm water for several hours and the fibers were taken out from the crucible. The obtained fibers were washed with cold water and then dried at io0°C. When this dried product was identified by X-ray powder diffraction method, it was found to be an intermediate phase between potassium tetratitanate and potassium nithimenate. When this is fired at 1000°C for 30 minutes, the length of the fibers obtained with good crystallinity decreases to the average Qt.
It was nm.

The results of carrying out the above method by changing the conditions of firing temperature and slow cooling rate are shown in Table 7 below.

Note that the comparative example is an example in which the slow cooling step was omitted.

In the same method as in Example 1, the steps of decomposition-melting-holding-slow cooling were repeated twice. The results were as shown in Table 2.

As the results show, long fibers are obtained compared to the fiber lengths in Table 1.

Claims (1)

[Scope of Claims] 1 general formula is 20n'l'i0□ (where n is ko<n<
A mixed composition of potassium oxide and titanium dioxide (hereinafter referred to as "mixed composition") represented by 3) or its manufacturing raw material mixture is heated and maintained at 1000 to 330°C to form a solid phase of potassium hexatitanate and a liquid. A mixed composition of phases is produced by a decomposition melting reaction, and from the temperature
After slowly cooling the mixture at a rate of 70° C./h' or less and adjusting the slow cooling rate to generate a mixed phase of solid potassium tetratitanate and liquid phase mixed composition by association reaction, A method for producing fibrous potassium titanate comprising a mixed phase fiber of potassium tetratitanate fibers and potassium nititanate fibers, the method comprising crystallizing potassium nititanate from a liquid phase mixed composition by cooling. 2. The method according to claim 1, wherein the heating-holding-slow cooling step is repeated two or more times.