JPS6317221A - Crystalline titanium oxide sol and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled sol composed of ultrafine particles, having excellent purity and dispersibility, etc., and stabilized with an alkaline ion, by reacting a water-soluble titanium compound with an alkali and subjecting the produced gel to hydrothermal treatment at a high temperature. CONSTITUTION:A water-soluble titanium compound (e.g. titanium tetrachloride) is made to react with an alkali metal hydroxide or carbonate and/or an ammonium compound to obtain a gel. The gel is filtered and washed to remove impurities, added with a water-soluble alkali (e.g. ammonium hydroxide) and subjected to hydrothermal treatment at >=100 deg.C to obtain crystalline anatase titanium oxide sol stabilized with alkaline ion and having particle diameter of <=500Angstrom . The obtained titanium oxide sol is useful for the delustering of artificial fiber, coating of paper, etc., as well as a raw material for IR-reflection multi-layer film, catalyst, piezoelectric material, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crystalline anatase-type titanium oxide sol stabilized with alkaline ions and a method for producing the same.

Titanium oxide is used as pigment, paste improver, humidity sensor,
It is an industrial material used in many fields such as infrared reflective multilayer films, catalysts, piezoelectric materials (titanate) raw materials, and titanium dioxide-coated mica.

(Prior Art) Titanium oxide raw material powder used for these purposes is usually obtained by adding sulfuric acid to ilmenite and hydrolyzing the sulfate to first obtain metatitanic acid. It is produced by a method in which it is filtered, dried, and calcined (sulfuric acid method), a hydrochloric acid method in which hydrochloric acid is used instead of sulfuric acid, or a method in which anhydrous titanium chloride is thermally decomposed in a gas phase.

However, titanium oxide powders obtained by these methods generally have coarse and irregular particle sizes, which poses a problem, especially when applied to fields that require uniform to ultra-fine particles.

On the other hand, a method of producing anhydrous titanium chloride by thermal decomposition in the gas phase is known, but although this method yields fine, uniform particles, the particles have poor dispersibility, and when dispersed in a solvent such as water, There is a problem with sedimentation and separation over time.

Furthermore, according to the content described in JP-A No. 59-223231, when producing titanium oxide using the sulfuric acid method, it is basically the same material as that added as a nuclear material in order to promote the rearrangement to the rutile type by calcination. It is called titania sol.

However, as is clear from the manufacturing method,
The titania sol obtained as an intermediate for producing fine-particle titanium oxide contains a large amount of acid, and is therefore different from the crystalline titanium oxide sol of the present invention.

Therefore, when applied to infrared reflective multilayer films, catalysts, raw materials for piezoelectric materials, mica coated with titanium dioxide, etc., these titanium dioxide powders do not have sufficient purity, particle size, and dispersibility, and problems remain. The current situation is that

(Problems to be Solved by the Invention) In view of these circumstances, the present inventors have conducted extensive research to obtain a crystalline titanium oxide sol that is excellent in purity, particle size, and dispersibility characteristics. discovered a new crystalline anatase-type titanium oxide sol stabilized with alkaline ions, and completed the present invention.

(Means for solving the problems) That is, the present invention relates to a crystalline anatase-type titanium oxide sol stabilized with alkaline ions and a method for producing the same.
Mizutoshi's invention is a crystalline anatase-type titanium oxide sol stabilized with alkaline ions with a particle size of 500A or less, and the second invention is a water-soluble titanium compound and an alkali metal hydroxide or carbonate sol. After reacting with a salt and/or an ammonium compound to generate a gel, this is
Particle size soo! resulting from hydrothermal treatment at 00℃ or higher!
The present invention relates to the following method for producing a crystalline anatase-type titanium oxide sol stabilized with alkaline ions.

(Function) First, the crystalline anatase-type titanium oxide sol stabilized with alkaline ions and having a particle size of 500 s or less, which is an invention by Mizue, will be explained in detail.

Conventionally, the method for manufacturing titanium oxide sol has been to use an inorganic titanium salt aqueous solution as a raw material and remove the acid groups contained therein by some method, or add titanium acetate to water and perform hydrolysis. A method has been proposed. Separately, methods have also been proposed in which titanium alkoxide is hydrolyzed by various means to obtain a sol.

However, the sols obtained by these methods are either amorphous or titanium hydroxide, and are not anatase-type crystalline titanium oxide sols.

In contrast, the crystalline titanium oxide sol stabilized with alkaline ions of the present invention has an anatase crystal form,
Moreover, this provides very fine colloidal particles of less than 500 mm in size in an aqueous solution state to form a stable sol solution.

Conventional amorphous sols cannot be crystallized when used for matting synthetic fibers, synthetic fibers, etc., or for coating paper manufacturing, due to the low heat resistance of the base material. Ta. However, the crystalline titanium oxide sol stabilized with alkaline ions of the present invention can be coated with a crystalline material on such a base material by low-temperature treatment such as drying. This is a significant improvement over the previous model, and it can be used under a wide range of conditions.

Such a sol has not been previously known and will create new uses in the field of application of titanium oxide composite materials.

Its characteristics are as follows.

First, the crystalline anatase-type sol stabilized with alkaline ions of the present invention can be obtained at a higher concentration than a non-formed sol, and can be used to create a multilayer infrared reflective film of titanium oxide-silica. In such cases, the desired film thickness and reflection performance can be obtained by coating twice.

Second, the crystalline anatase-type titanium oxide sol stabilized with alkaline ions of the present invention has excellent sol stability, so conventional titanium dioxide powder can form a uniform film during coating and other operations. In contrast, with the product of the present invention, the sol is evenly dispersed even after long-term storage.
A uniform coating film can be obtained.

Moreover, since they are ultrafine particles of 5ooX or less, when applied to a humidity or gas sensor containing tin or vanadium in titanium oxide, a sensor with extremely high sensitivity can be obtained due to the large specific surface area.

Furthermore, since it is possible to coat at a higher concentration than an amorphous sol, a tough product can be obtained.

These facts are very useful in the production of titanium oxide ceramic coating films.

The colloidal particle size was measured by electron microscopic observation, and in the sol of the present invention, substantially all colloidal particles had a particle size of 500X or less.

Next, a method for producing a crystalline anatase-type titanium oxide sol stabilized with alkaline ions, which is the second invention, will be described in detail.

The second invention provides particles obtained by reacting a water-soluble titanium compound with an alkali metal hydroxide or carbonate, and/or an ammonium compound to form a gel, and then hydrothermally treating the gel at a temperature of 1008C or higher. The present invention relates to a method for producing a crystalline anatase-type titanium oxide sol stabilized with alkaline ions having a diameter of 500 Å or less. Examples of water-soluble titanium compounds used in the present invention include titanium tetrachloride, titanium nitrate, and titanium sulfate. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, and alkali metal carbonate. Examples of the salt include sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and the like.

Further, examples of ammonium compounds include ammonium bicarbonate, ammonium carbonate, aqueous ammonia, etc., but are not limited thereto.

In the present invention, first, the water-soluble titanium compound and an alkali metal hydroxide or carbonate, and/or an ammonium compound are reacted to form a gel.

Regarding the conditions for producing this gel, the temperature during the reaction between the two is approximately 10 to 90°C.

Regarding the addition ratio, the equivalent ratio A/B of the alkali metal hydroxide or carbonate and/or ammonium compound (A) and the acid radical derived from the water-soluble titanium compound (B) is 1.0 to 1. Do this so that it falls within the range of 3.

However, even if it deviates from this range, in the step of washing the produced gel described below, if the upper limit is exceeded, washing with a dilute acid solution is performed, and if it is below the lower limit, the desired result is washed with a dilute alkaline solution. Although not particularly limited, the above range is desirable for economic reasons. There is also no particular limitation on the order of addition, with either the water-soluble titanium compound or the ammonium compound added first. This can be carried out by adding either one or both at the same time.

The gel thus produced is then filtered and washed to remove impurities.

It is preferable that the amount of residual impurities be as small as possible in terms of the production and use of the titanium oxide sol. For example, if the above-mentioned filtration and cleaning operation is not performed at all, the resulting sol will be unstable, and the sol of the present invention will not be able to be used. can't get it.

The filtration and washing means are not particularly limited, and any commonly used means such as a filter press, water filtration such as centrifugal filtration, repulp-centrifugation method, etc. can be used.

After filtration and washing, a water-soluble alkali is added to the gel,
Subject to hydrothermal treatment.

Examples of the water-soluble alkali to be added include ammonium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, methylamine, trimethylamine, ethylenediamine, and ethanolamine.

Further, the amount of water-soluble alkali added is approximately 0.00000000000000000000000000000000000000000000000 O is in the range of 1 to 0.60 mol, and the pH of the sol is in the range of 8 to 12, more preferably PH 9 to 11.
Do this so that it falls within the range of 5.

In this case, if the amount added exceeds this range, the sol with excellent dispersibility of the present invention cannot be obtained.

Regarding the hydrothermal treatment conditions, the temperature is 10,000 or higher, and generally, the higher the treatment temperature and the longer the treatment time, the better the development of crystal form and the larger the particle size can be obtained.

In addition, if the treatment is carried out at a temperature below 1000C, the gel will not crystallize even if it is carried out for a long time, and even if a part of it crystallizes, its crystallinity will be extremely low and its amorphous nature will remain, which is the object of the present invention. cannot be achieved.

An advantage of the present invention is that it is possible to obtain a sol with a desired particle size by selecting treatment conditions according to each use of the crystalline titanium oxide sol of the present invention, and that this can be controlled by selecting the hydrothermal treatment conditions. This is a major feature of

(Example 54) Examples of the present invention will be listed below to further explain the present invention, but the present invention is not limited thereto.

Moreover, unless otherwise specified, all percentages indicate weight percent.

Example 1 2000 g of titanium tetrachloride aqueous solution 9i (Ti022%) and 2212 g of ammonia water (NH32%) (NH3/CI
An equivalent ratio of 1.3) was added under stirring to form a gel.

This was filtered and washed with water until no chloride ions were observed in the filtrate, to obtain a gel containing 10% Ti08 and 30.3% NH.

Add 11 ammonium hydroxide (NH34, 5%) to 400 g of this gel so that the NH3/τ102 molar ratio is 0.2.
．． Add 2g and put this in an autoclave, 160
Hydrothermal treatment was carried out at °C for 4 hours to obtain the sol of the present invention. Note that the pH of this sol solution was 10.8.

Further, when this sol was diluted to 1.0% Ti0 and left to stand, the dispersion stability rate after 1 month was 99%. Furthermore, the colloid particle diameter was 105A when observed under an electron microscope, and the result of X-ray diffraction showed that it was anatase type crystalline.

The dispersion stability rate was calculated by measuring the 1102 concentration of a liquid sampled from the upper layer of the sol liquid after one month, and using the following formula.

Examples 2 to 4 10,000 g of titanium tetrachloride aqueous solution (11,083%) and 18,135 g of sodium bicarbonate aqueous solution (Na 2%) (H
a/cl equivalent ratio of 1.05) was simultaneously added to a reaction tank to which 5000 g of water had been previously added while stirring.

The generated gel was washed with water and filtered to obtain 2758 g of gel containing 10.8% Tide. This gel was diluted with water and τ1
Add sodium hydroxide to 400g of gel with a concentration of 0.3%.
/TiO□ molar ratio of 0.08, this was placed in an autoclave, and treated under the treatment conditions shown in Table 1 to obtain the sol of the present invention. Note that the pH of this sol solution was 11.3.

These X-ray diffraction results are shown in Table 1, and the X-ray diffraction diagram of Example 2 is shown in FIG.

Furthermore, from the results of X-ray diffraction, 5cherrer's formula % formula %
The particle diameter was calculated using () β: half width (run 9 am) cos θ; 2θ = 25.3”.

The particle size is the particle size from the electronic al@mirror observation result and 5ch
The particle diameters from the error equation were almost the same.

Further, as a comparative example, the same amount of the above gel was placed in a Mitsuro flask and treated with a mantle heater under the conditions listed in Table 1. The results are shown in Table 1.

Table 1 Example 5 10000g of sodium carbonate aqueous solution (Na1%) and 8515g of titanium nitrate aqueous solution (11021%) (Na/
NO3 equivalent ratio 1.02) was added with stirring. After thoroughly washing the obtained gel with water and confirming that no nitric acid remained in the wet cake, it was diluted with water to obtain a slurry containing 28% Ti.

Next, 5.4 g of 25% ammonia water was added to 400 g of this slurry so that the NH8/TIQe molar ratio was 0.2, and hydrothermal treatment was performed at 200° C. for 4 hours to obtain the sol of the present invention. Note that the pH of this sol solution was 10.1.

As a result of X-ray diffraction, the sol of the present invention had an anatase crystal form, a particle size of 1aoX, and a dispersion stability rate of 92%.

Example 6 In the same manner as in Example 5, a gel was obtained using an aqueous sodium carbonate solution and an aqueous titanium nitrate solution. This gel slurry (Ti02
8%) to 400 g of NH2/τi0. Molar ratio 0.02
By adding 0.49 g of monoethanolamine and performing hydrothermal treatment at 200'C for 4 hours,
A sol of the present invention having a sol liquid pH of 11.5 was obtained.

As a result of X-ray diffraction, the sol of the present invention had an anatase crystal form, a particle size of 180'A, and a dispersion stability rate of 89%.

Example 7 Titanium nitrate aqueous solution (TiO33%) 2000g and ammonia water (NH33%) 221;'g (NH3/NO3
(equivalent ratio 1.3) was added under stirring to form a gel.

This was filtered and washed with water until no nitrate ions were observed in the filtrate, yielding a gel containing 10.6% of 1102 and 29% of NH3.

Add (NH3+Na)/Ti0I to 400g of Conogel! −
! Sodium hydrogen carbonate is 7.6 to give a nil ratio of 0.3.
g and put it in an autoclave at 250°C.
After 2 hours of hydrothermal treatment, the sol liquid P)I was 10.3
A sol of the present invention was obtained.

As a result of X-ray diffraction, this sol of the present invention had an anatase type crystal form, a particle size of 180, and a dispersion stability rate of 96%.

For comparison, a gel was obtained in the same manner as above and then autoclaved without any filtration and water washing. As a result, the liquid pH was 9.4, but this product did not exhibit a sol state.

[Brief explanation of drawings]

Figure 1 shows the crystalline anatase type titanium oxide sol stabilized with alkaline ions of the present invention obtained in Example 2 at 60°C.
It is an X-ray diffraction diagram of a dried product.

Claims (2)

[Claims] (1) Crystalline anatase-type titanium oxide sol stabilized with alkaline ions with a particle size of 500 Å or less. (2) A particle size of 500 Å or less is obtained by reacting a water-soluble titanium compound with an alkali metal hydroxide or carbonate, and/or an ammonium compound to form a gel, and then hydrothermally treating the gel at 100°C or higher. A method for producing a crystalline anatase-type titanium oxide sol stabilized with alkaline ions.