JP2783417B2 - Manufacturing method of rutile type titanium oxide sol - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a rutile-type titanium oxide sol.

Technical Background of the Invention and Problems Thereof In recent years, titanium oxide particles have been widely used in applications utilizing their chemical properties. For example, titanium oxide has an appropriate bonding force with oxygen and also has acid resistance,
Used as an oxidation-reduction catalyst, used as a surface coating material for decorative materials or plastics by using ultraviolet blocking power, used as an anti-reflection coating material using a high refractive index, It is used as an antistatic material used, or is used as a functional hard coat material or the like by combining these effects.

As described above, titanium oxide is used in many applications, but in any case, titanium oxide requires many functions. For example, when using titanium oxide as a catalyst, not only activity to the main reaction, but also selectivity, mechanical strength, heat resistance, acid resistance or durability are required, and when using titanium oxide as a cosmetic material, In addition, not only the effect of blocking ultraviolet rays, but also smoothness, texture, and transparency are required. Further, when titanium oxide is used as a coating material, in addition to transparency and high refractive index, further excellent film forming properties, adhesion, film hardness, mechanical strength, wear resistance, and the like are required.

As described above, in order to use titanium oxide particles for various purposes, the titanium oxide particles are required to have various characteristics according to each application. Preferably, there is. Moreover, when transparency is required for the titanium oxide particles, these particles are not only uniform in particle shape and size, but also
It is required to be highly dispersed in a medium during compounding. To produce titanium oxide particles that satisfy these properties,
It is particularly preferable to use highly dispersed colloidal titanium oxide (titanium oxide sol).

By the way, titanium oxide is classified into anatase type and rutile type. The anatase type is inferior to the rutile type in light resistance, heat resistance, ultraviolet absorbing ability, and the like. Therefore, rutile type titanium oxide is preferable.

As a method for producing such a rutile-type titanium oxide sol in which the rutile-type titanium oxide fine particles are dispersed, a hydrated titanium oxide obtained by hydrolyzing an aqueous solution of a titanium salt is treated with a caustic alkali, and then ripened in hydrochloric acid. It has been known.

Rutile-type titanium oxide sol obtained by these methods,
Since the sol contains anions derived from titanium salts or metal ions derived from alkalis, it is necessary to remove these. However, it is extremely difficult to wash and remove these ions from the sol. Further, the conventional sol has a problem that it can stably exist only in an acidic region.

JP-A-63-210027 discloses that a mixed gel of a titanium compound and a tin compound is subjected to hydrothermal treatment to obtain a crystalline titanium oxide / tin oxide sol.

By the way, the applicant of the present application dissolves anatase-type titanium oxide particles characterized in that after hydrated titanium oxide gel or sol is dissolved with hydrogen peroxide, heating and hydrolysis are performed in the presence of an inorganic compound such as SiO _2. A patent application was filed for a method for producing the titanium oxide sol thus obtained (Japanese Patent Application Laid-Open No. 63-229139).

The present inventors have conducted intensive studies based on the above-described technology, and as a result, dissolve the hydrated titanium oxide by adding hydrogen peroxide to a gel or sol of hydrated titanium oxide having a specific specific surface area, The inventors have found that if the obtained solution is heated in the presence of a specific amount of SnO ₂ , the dispersed particles in the obtained titanium oxide sol will be rutile-type titanium oxide, and have completed the present invention.

An object of the present invention is to solve the above problems, and to provide a method for producing a rutile-type titanium oxide sol having excellent dispersibility, long-term stability, and excellent light resistance. It is an object.

SUMMARY OF THE INVENTION A method for producing a rutile-type titanium oxide sol according to the present invention comprises:
Hydrogen peroxide is added to a gel or sol of hydrated titanium oxide containing hydrated titanium oxide particles having a specific surface area of 150 m ² / g or more to dissolve the hydrated titanium oxide, and then the obtained solution is
It is characterized by heating in the presence of a tin compound in an amount of O ₂ / SnO ₂ = 1.5 to 14 (weight ratio).

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the rutile-type titanium oxide sol according to the present invention will be specifically described.

In the present invention, to produce a rutile-type titanium oxide sol,
First, a hydrated titanium oxide gel or sol is prepared by a conventionally known method. The hydrated titanium oxide gel can be obtained, for example, by neutralizing an aqueous solution of a titanium salt such as titanium chloride or titanium sulfate by adding an alkali, and washing the resultant. The hydrated titanium oxide sol can be obtained by passing an aqueous solution of a titanium salt through an ion exchange resin to remove anions, or hydrolyzing a titanium alkoxide.

Hydrated titanium oxide particles in the obtained gel or sol,
It is preferably amorphous, and its specific surface area is
It is desirably 150 m ² / g or more, preferably 155 m ² / g or more, in order to obtain rutile-type titanium oxide.

The term “hydrated titanium oxide” as used herein is a general term for what is called a hydrate of titanium oxide, titanium hydroxide or hydrous titanic acid obtained by the above method.

The specific surface area according to the present invention is a value obtained by drying a gel or sol and calcining the powder after firing at 280 ° C. for 160 hours by the BET method.

Next, hydrogen peroxide is added to the hydrated titanium oxide sol or gel obtained as described above or a mixture thereof to dissolve the hydrated titanium oxide to form a uniform aqueous solution (hereinafter sometimes referred to as a titanic acid aqueous solution). Prepare. When preparing such an aqueous solution of titanic acid, if necessary, about 50 ° C
It is preferable to heat or stir as described above. At this time, if the concentration of the hydrated titanium oxide is too high, it takes a long time to dissolve the hydrated titanium oxide, and an undissolved gel may precipitate, or the resulting aqueous solution may become viscous. Therefore, the TiO ₂ concentration is desirably about 10% by weight or less, preferably about 5% by weight or less.

The amount of hydrogen peroxide to be added is 1 in H ₂ O ₂ / TiO ₂ weight ratio.
With the above, the hydrated titanium oxide can be completely dissolved. If the H ₂ O ₂ / TiO ₂ ratio is less than 1, the hydrated titanium oxide may not completely dissolve and unreacted gel or sol may remain. Also, as the H ₂ O ₂ / TiO ₂ ratio increases, the dissolution rate of hydrated titanium oxide increases and the reaction is completed in a short period of time. It only remains in large quantities inside, and is not economical. When hydrogen peroxide is used in such an amount, the hydrated titanium oxide is completely dissolved in about 0.5 to 20 hours.

Next, a tin compound is added to the obtained aqueous solution of titanic acid.

As the tin compound, tin salts such as tin chloride and tin nitrate, stannates such as potassium stannate, or oxides and hydroxides are used.

These tin compounds are usually added in the form of an aqueous solution, but may be added in powder form. Further, a tin oxide hydrate gel or sol may be added.

The amount of tin compound added is expressed as TiO ₂ / SnO ₂ (weight ratio)
It is selected from the range of 1.5 to 14, preferably 2 to 10.

When the addition amount of the tin compound is made smaller than the above range, the crystal structure shifts from the rutile structure, and anatase-type titanium oxide is obtained. Further, when the addition amount is increased beyond the above range, a crystal structure different from the rutile structure comes to be exhibited.

The mixed solution to which the tin compound has been added is then heated to a temperature of about 60 ° C. or higher, preferably 80 ° C. or higher, and hydrolyzed to obtain the desired rutile-type titanium oxide sol.

The method of mixing the aqueous solution of titanic acid and the tin compound is not particularly limited, and a predetermined amount of the aqueous solution of titanic acid and the tin compound may be mixed at a time, or a part of the aqueous solution of titanic acid and a part of the tin compound may be mixed first. The mixture may be heated, and the remainder of the two may be added as the reaction proceeds.

Further, a method in which the entire amount of the tin compound and a part of the aqueous solution of titanic acid are first mixed and heated, and then the remaining aqueous solution of titanic acid may be added.

The mixing time of the tin compound does not necessarily need to be after the hydrated titanium oxide is dissolved in the hydrogen peroxide, but may be mixed in a gel or sol stage before being dissolved in the hydrogen peroxide. It may be mixed at the time of preparing the gel or sol of the titanium oxide. In short, when the titanic acid aqueous solution is heated and hydrolyzed, the tin compound described above may be present in the reaction system.

In the present invention, the stability of the resulting rutile-type titanium oxide sol can be increased by heating and hydrolyzing a mixed aqueous solution of a titanic acid aqueous solution and a tin compound in the presence of a silicon compound.

When adding a silicon compound, the addition amount of the silicon compound is preferably 0.05 to 0.2 (weight ratio) as SiO ₂ / (TiO ₂ + SnO ₂ ), and the silicon compound may be an alkali such as water glass. Metal silicate, or a silicic acid solution obtained by removing alkali metal silicate aqueous solution,
Alternatively, silica gel, silica sol, or the like is used.

The dispersed particles of the rutile-type titanium oxide sol thus obtained consist of crystal grains having a size of about 40 to 150 ° (Debye-Scherrer method) grown or polycrystals in which crystal grains are aggregated. It is a sol in which extremely uniform particles having a particle size in the range of about 5 to 100 mμ are dispersed.

Such a titanium oxide sol obtained by the present invention,
Although it can be used for the intended use as it is, it can be used after being concentrated to an appropriate concentration by a known method such as evaporation under reduced pressure and ultrafiltration. Further, depending on the application, an organic solvent dispersion sol can be prepared by mixing or solvent replacement with an alcohol such as isopropanol, a glycol such as ethylene glycol, or an organic solvent such as dimethylformamide. Further, by the surface treatment of the titanium oxide particles, an organic solvent dispersion sol such as toluene and xylene can be obtained.

Therefore, if the rutile-type titanium oxide sol obtained by the present invention is used as a compounding agent for plastics, various effects such as prevention of deterioration of plastics due to ultraviolet rays can be expected. Long-term storage becomes possible in comparison.

Further, the rutile-type titanium oxide fine particles obtained by the present invention have the same effect as the conventional rutile (TiO ₂ ) with an ultraviolet shielding effect.
Since it has almost the same high refractive index as that of, and exhibits electrical conductivity, it can be used as a surface coating agent for substrates such as glass and plastics to obtain a high refractive index conductive film with excellent transparency and ultraviolet shielding effect. Can be Therefore, it is useful as a coating agent for a lens that requires a high refractive index or a front plate coating agent for a cathode ray tube or the like that requires an antistatic function. In addition, an antistatic fiber can be obtained by blending it with a synthetic fiber.

Effects of the Invention The rutile-type titanium oxide sol obtained by the present invention has excellent dispersibility and long-term stability, excellent light resistance, and also with respect to the ultraviolet shielding effect and transparency, the conventional titanium oxide fine particle dispersion and In comparison, it has excellent characteristics. Moreover, no gelation or precipitation occurs even when mixed with or replaced with an organic solvent.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

To obtain an aqueous solution containing 1.0 wt% as TiO ₂ by diluting Example 1 of titanyl sulfate solution with pure water. While maintaining the aqueous solution at 10 ° C., 15% by weight aqueous ammonia was added with stirring, and the pH was adjusted.
= 9.5 as a white slurry. This slurry was filtered and washed to obtain a hydrated titanium oxide gel cake having a solid content of 10.2% by weight.

After adding 771 g of 35% hydrogen peroxide solution and 597 g of pure water to 882 g of the cake, the mixture was heated at 83 ° C. for 3 hours to obtain TiO _2.
2250 g of a 4.0% by weight aqueous solution of titanic acid were obtained. This aqueous solution of titanic acid was yellow-brown and transparent and had a pH of 8.8.

Next, 626 g of a 1.6% by weight stannic acid aqueous solution as SnO ₂ obtained by dealkalizing the potassium stannate aqueous solution with a cation exchange resin.
And 2250 g of the above titanic acid aqueous solution and 6020 g of pure water were mixed. Further, 94.6 g of a silica sol having an average particle diameter of 7 μm and a silica concentration of 15% by weight was mixed with the above mixed solution, and then heated at 150 ° C. for 18 hours. The solution was initially tan, but after 18 hours became a pale milky-blue, clear colloid.

The colloid liquid thus obtained was concentrated to a solid content concentration of 25.6% by weight by a vacuum evaporation method to obtain a stable titanium oxide sol. The specific surface area, crystallite diameter (by the Debye-Scherrer method), and X-ray diffraction pattern of the dispersed particles of the sol were measured. The results are shown in Table 1 and FIG.

The X-ray diffraction was measured after drying the sol-dispersed particles at 110 ° C., under the conditions of LAD-II C type manufactured by Rigaku Corporation, Cu bulb, 35 KV, 12.5 mA.

From this X-ray diffraction, it can be seen that the obtained titanium oxide sol is of a rutile type.

Example 2 The aqueous solution of titanic acid, the aqueous solution of stannic acid and pure water of Example 1 were mixed, and TiO ₂ / SnO ₂ = 2.3 (wt / wt), (TiO ₂ + SnO ₂ )
A 0.5% by weight mixed aqueous solution was prepared. After that, Example 1
In the same manner as in the above, a titanium oxide sol was obtained. The results are shown in Table 1 and FIG.

Example 3 Cation exchange resin particles were added to the aqueous solution of titanic acid of Example 1 to adjust the pH to 3.8. To this, a 3.0% by weight aqueous solution of potassium stannate as SnO ₂ was added, and TiO ₂ /
It was gradually added until SnO ₂ = 9 (wt / wt). Thereafter, the cation exchange resin particles were separated, and the silica sol and pure water used in Example 1 were added, and SiO ₂ / (TiO ₂ + SnO ₂ ) = 0.17 (w)
t / wt), a mixed aqueous solution having a (SiO ₂ + TiO ₂ + SnO ₂ ) concentration of 2.0% by weight. This was heated at 180 ° C. for 12 hours. The solution is
Initially a tan color, it turned into a pale milky blue transparent colloid after 12 hours.

The properties of the dispersed particles of titanium oxide sol obtained by concentrating this colloid solution in the same manner as in Example 1 are shown in Table 1 and FIG.

Example 4 Titanium tetrachloride and stannic chloride were combined with TiO ₂ / SnO ₂ = 9 (wt /
wt) and pure water so as to give a solid content (TiO ₂ + SnO ₂ ) concentration of 4% by weight, and mixed and dissolved. Add 5% by weight of ammonia water to this so that the liquid temperature does not exceed 20 ° C.
It was added until pH 9.5. The resulting gel is washed with 0.5% by weight of ammonia water and then with pure water to obtain a solid content of 1%.
877.2 g of a 1.4% mixed gel was obtained. After adding 1429 g of 35 wt% hydrogen peroxide solution and 2694 g of pure water, the mixture was heated at 83 ° C. for 4 hours to obtain 5 kg of a 2.0 wt% solution as (TiO ₂ + SnO ₂ ). This solution was tan transparent and had a pH of 9.1.

Next, the average particle size is 5mμ, and the silica concentration is 15% by weight.
Was mixed with 5 kg of the above yellow-brown transparent liquid and 4.5 kg of pure water, and heated at 143 ° C. for 172 hours. The solution was initially a tan transparent liquid, but after 172 hours became a pale milky pale white transparent colloid liquid.

The colloid solution thus obtained was concentrated to a solid concentration of 24.5% by weight with an ultramembrane to obtain a stable titanium oxide sol. The properties of the dispersed particles of the obtained sol are shown in Table 1 and FIG.

Example 5 A titanium oxide sol was produced in the same manner as in Example 1 except that silica sol was not added. The properties of the dispersed particles of the obtained sol are shown in Table 1 and FIG.

Example 6 Using an aqueous solution of titanyl sulfate having a TiO ₂ concentration of 7.4% by weight,
An aqueous solution of titanic acid was prepared in the same manner as in Example 1. Next, a titanium oxide sol was produced in the same manner as in Example 3 using this titanic acid aqueous solution. The properties of the resulting titanium oxide sol dispersed particles are shown in Table 1 and FIG.

Comparative Example 1 A titanium oxide sol was obtained in the same manner as in Example 1 except that a stannic acid aqueous solution having a SnO ₂ concentration of 0.8% by weight was used.

Comparative Example 2 The titanyl sulfate solution was diluted with pure water to obtain TiO ₂ of 5.0.
An aqueous solution containing about 10% by weight was obtained. While stirring this aqueous solution, 15% aqueous ammonia was added to obtain a white slurry having a pH of 9.5. The liquid temperature during the addition was about 40 ° C. The slurry was filtered and washed to obtain a hydrated titanium oxide gel cake having a solid content of 15.1% by weight.

After adding 771 g of 35% hydrogen peroxide solution and 883 g of pure water to 596 g of the cake, the mixture was heated at 83 ° C. for 3 hours to obtain 2250 g of a 4.0% by weight titanic acid aqueous solution as TiO ₂ . This aqueous solution of titanic acid was yellow-brown and transparent and had a pH of 8.7.

Add cation exchange resin particles to this titanic acid aqueous solution
The pH was adjusted to 3.8. The subsequent operations and conditions are described in Example 3.
In the same manner as in the above, a titanium oxide sol was obtained.

Comparative Example 3 A titanium oxide sol was obtained in the same manner as in Example 3, except that potassium stannate was added so that TiO ₂ / SnO ₂ = 1 (wt / wt).

The properties of the dispersed particles of the titanium oxide sol obtained in Comparative Examples 1 to 3 are shown in Table 1, FIG. 7, FIG. 8, and FIG.

[Brief description of the drawings]

1 to 6 are X-ray diffraction diagrams of titanium oxide in a rutile-type titanium oxide sol obtained by the present invention, and FIGS. 7 to 9 are graphs of titanium oxide sol obtained in a comparative example. FIG. 3 is an X-ray diffraction diagram of titanium oxide.

Claims (1)

(57) [Claims] 1. Hydrogen peroxide is added to a gel or sol of hydrated titanium oxide containing hydrated titanium oxide particles having a specific surface area of 150 m ² / g or more to dissolve the hydrated titanium oxide, and then obtain a solution. Is heated in the presence of a tin compound in an amount of TiO ₂ / SnO ₂ = 1.5 to 14 (weight ratio) in a rutile-type titanium oxide sol.