JPH02255532A - Production of rutile type titanium oxide sol - Google Patents

Abstract

PURPOSE:To obtain the title sol which is excellent in dispersibility and is also excellent in long-term stability and light resistance by heating a soln. prepd. by dissolving the gel or sol of titanium hydroxide in hydrogen peroxide in the presence of a specific ratio of a tin compd. CONSTITUTION:An alkali is added to an aq. sol. of a Ti salt, such as titanium chloride, to neutralize the soln. and the soln. is washed to obtain the titanium hydroxide gel. The aq. soln. of the Ti salt is otherwise passed through an ion exchange resin to remove anions therefrom or to hydrolyze the titanium alkoxide to obtain the titanium hydroxide sol. The hydrogen peroxide is added to the resulted gel or sol or the mixture composed of both to dissolve the titanium hydroxide. The uniform aq. soln. is thus prepd. The tin compd. (tin salt, such as tin chloride, stannic acid salt, such as potassium stannate, the oxide or hydroxide of tin) is added to this aq. soln. at a ratio of TiO2/SnO2=1.5 to 14 (by weight) and thereafter, the soln. is heated and is thereby hydrolyzed. The rutile type titanium oxide sol is thus obtd.

Description

[Detailed description of the invention] Technical field of invention The present invention relates to a method for producing a rutile-type titanium oxide sol.

In recent years, titanium oxide particles have been increasingly used to utilize their chemical properties. For example, titanium oxide has an appropriate bonding strength with oxygen and is also acid resistant.
It is used as a redox catalyst, or as a surface coating material for cosmetic materials or plastics due to its ultraviolet blocking power, or as an antireflection coating material due to its high refractive index, or as a conductive material. It is used as an antistatic material, and it is also used as a functional hard coat material by combining these effects.

As mentioned above, titanium oxide is used for many purposes, but in each case, titanium oxide is required to have many functions. For example, when using titanium oxide as a catalyst, not only the activity for the main reaction but also the selectivity and
Mechanical strength, heat resistance, acid resistance, and durability are required, and when titanium oxide is used as a cosmetic material, it is required not only to have a UV shielding effect but also to have smoothness, texture, and transparency. . Furthermore, when titanium oxide is used as a coating material, in addition to transparency and high refractive index, it is required to have even better film forming properties, adhesion, film hardness, mechanical strength, abrasion resistance, and the like.

In order to use titanium oxide particles for various purposes,
Titanium oxide particles are required to have various properties depending on their use, but ultrafine particles are preferable no matter what purpose they are used for. Moreover, when titanium oxide particles are required to have transparency, the particles are required not only to be uniform in particle shape and size, but also to be highly dispersed in the medium during blending. : In order to produce titanium oxide particles that satisfy these characteristics, it is particularly preferable to use highly dispersed colloidal titanium oxide (titanium oxide sol).

By the way, there are two types of titanium oxide: anatase type and rutile type, and since anatase type is inferior to rutile type in terms of light resistance, heat resistance, ultraviolet absorption ability, etc., rutile type titanium oxide is preferable.

A method for producing such a rutile-type titanium oxide sol in which rutile-type titanium oxide fine particles are dispersed includes a method of treating hydrated titanium oxide obtained by hydrolyzing an aqueous titanium salt solution with caustic alkali, and then aging it in hydrochloric acid. It has been known.

The rutile-type titanium oxide sols obtained by these methods contain anions derived from titanium salts or metal ions derived from alkali, so these must be removed. However, it is extremely difficult to wash these ions out of the sol. Furthermore, conventional sols have problems such as being able to exist stably only in an acidic region.

Further, JP-A-63-210027 discloses that a crystalline titanium oxide/tin oxide sol can be obtained by hydrothermally treating a mixed gel of a titanium compound and a tin compound.

By the way, the applicant of the present application has disclosed that anatase-type titanium oxide particles are dispersed by first dissolving a hydrated titanium oxide gel or sol with hydrogen peroxide, and then heating and hydrolyzing it in the coexistence of an inorganic compound such as SiO2. A patent application was filed for a method for producing titanium oxide sol (Japanese Unexamined Patent Publication No. 63-229139).

As a result of extensive research based on the above technology, the present inventors added hydrogen peroxide to the gel or sol of hydrated titanium oxide to dissolve the hydrated titanium oxide, and identified the resulting solution. The present inventors have discovered that when heated in the presence of a certain amount of SnO2, the dispersed particles in the resulting titanium oxide sol become rutile-type titanium oxide, and have completed the present invention.

Purpose of the Invention The present invention aims to solve the above-mentioned problems, and provides a method for producing a rutile-type titanium oxide sol that has excellent dispersibility, long-term stability, and light resistance. It is an object.

Summary of the Invention The method for producing a rutile-type titanium oxide sol according to the present invention includes adding hydrogen peroxide to a gel or sol of hydrated titanium oxide to dissolve the hydrated titanium oxide, and then adding the resulting solution to Ti
It is characterized by heating in the coexistence of a tin compound in an amount of O/S n O2 = 1, 5 to 14 (weight ratio).

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

In the present invention, in order to produce a rutile-type titanium oxide sol, first, a gel or sol of hydrated titanium oxide is prepared by a conventionally known method. Hydrated titanium oxide gel can be obtained, for example, by adding an alkali to an aqueous solution of a titanium salt such as titanium chloride or titanium sulfate, neutralizing the solution, and washing the solution. Further, a 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 by hydrolyzing titanium alkoxide.

The hydrated titanium oxide particles in the obtained gel or sol are preferably amorphous, and further have a specific surface area of 1
50r+f/g or more preferably 155rr? /g or more is desirable in order to obtain rutile-type titanium oxide.

The hydrated titanium oxide herein is a general term for hydrated titanium oxide obtained by the above method, titanium hydroxide, or hydrated titanic acid.

Note that the specific surface area of the present invention is determined by drying the gel or sol,
This is a value measured by the BET method on the powder after firing at 280° C. for 16 hours.

Next, hydrogen peroxide is added to the hydrated titanium oxide sol or gel or a mixture thereof obtained as described above to dissolve the hydrated titanium oxide to form a homogeneous aqueous solution (hereinafter sometimes referred to as titanic acid aqueous solution). Prepare. When preparing such a titanic acid aqueous solution, the temperature may be adjusted to about 50°C as necessary.
It is preferable to heat or stir the mixture to a higher level. At this time, if the concentration of hydrated titanium oxide becomes too high, it will take a long time to dissolve it, and undissolved gel may precipitate, or the resulting aqueous solution may become viscous. Therefore, the T L 02 concentration is approximately 10% by weight.
The content is preferably about 5% by weight or less.

The amount of hydrogen peroxide to be added can completely dissolve hydrated titanium oxide as long as the H20□/TiO2 weight ratio is 1 or more. When the H202/TiO2 ratio is less than 1, hydrated titanium oxide may not be completely dissolved, and unreacted gel or sol may remain. Also H20□/T
The larger the L O□ ratio, the higher the dissolution rate of hydrated titanium oxide, and the reaction will complete in a shorter time. However, even if hydrogen peroxide is used in excess, a large amount of unreacted hydrogen peroxide will remain in the system. It is not economical. When hydrogen peroxide is used in such an amount, hydrated titanium oxide is completely dissolved in about 0.5 to 20 hours.

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

Examples of tin compounds include tin salts such as tin chloride and tin nitrate;
A stannate such as potassium stannate, or an oxide or hydroxide is used.

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

The amount of tin compound added is T iO2/S n O2 (
(weight ratio) is selected from the range of 1.5 to 14, preferably 2 to 10.

When the amount of the tin compound added is reduced below the above range, the crystal structure shifts from the rutile structure, resulting in anatase-type titanium oxide. Furthermore, if the amount added is increased beyond the above range, a crystal structure different from the rutile structure will 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.

There are no particular restrictions on the method of mixing the titanic acid aqueous solution and the tin compound, and a predetermined amount of the titanic acid aqueous solution and the tin compound may be mixed at once, or a portion of the titanic acid aqueous solution and a portion of the tin compound may be mixed first. Mix and heat, and as the reaction progresses, the remainder of both may be added.

Furthermore, it is also possible to first mix and heat the entire amount of the tin compound and a portion of the titanic acid aqueous solution, and then add the remaining titanic acid aqueous solution.

Furthermore, the timing of mixing the tin compound does not necessarily have to be after the hydrated titanium oxide has been dissolved in peracid and hydrogen hydride; it may be mixed in the gel or sol stage before being dissolved in hydrogen peroxide; may be mixed during the preparation of the hydrated titanium oxide gel or sol. In short, when heating and hydrolyzing a titanic acid aqueous solution, it is sufficient that the above-mentioned tin compound is present in the reaction system.

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

When adding a silicon compound, the amount of the silicon compound added is 0.
05 to 0.2 (weight ratio), and the silicon compound includes alkali metal silicates such as water glass,
Alternatively, a silicic acid solution obtained by dealkalizing an aqueous alkali metal silicate solution, silica gel, silica sol, or the like may be used.

The dispersed particles of the rutile-type titanium oxide sol obtained in this way consist of crystal grains with a size of about 40 to 150 people (Debye-Sierer method) grown, or a polycrystalline body of aggregated crystal grains. It is a sol in which extremely uniform particles having an average particle size in the range of about 5 to 100 mμ are dispersed.

The titanium oxide sol obtained by the present invention can be used as it is for the intended purpose, but it can be used by vacuum evaporation,
It can also be used after being concentrated to an appropriate concentration by a known method such as ultrafiltration. Depending on the application, it can also be mixed with or replaced with an alcohol such as isopropanol, a glycol such as ethylene glycol, or an organic solvent such as dimethylformamide to form an organic solvent-dispersed sol. Furthermore, by surface treatment of titanium oxide particles, a sol dispersed in an organic solvent such as toluene or xylene can also 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 preventing deterioration of plastics due to ultraviolet rays can be expected. In comparison, long-term storage is possible.

Furthermore, the rutile-type titanium oxide fine particles obtained by the present invention have an ultraviolet shielding effect as well as the conventional rutile (TiO□
), and it also exhibits conductivity, so if used as a surface coating agent for substrates such as glass and plastic, it can create a high refractive index conductive film with excellent transparency and ultraviolet shielding effects. can get. Therefore, it is useful as a coating agent for lenses that require a high refractive index, or as a coating agent for front plates of cathode ray tubes and the like that require an antistatic function. Moreover, by blending it with synthetic fibers, antistatic fibers can be obtained.

Effects of the Invention The rutile-type titanium oxide sol obtained by the present invention has excellent dispersibility, long-term stability, and light resistance, and is superior to conventional acid and titanium oxide fine particle dispersions in terms of ultraviolet shielding effect and transparency. It has superior properties compared to liquids. Furthermore, even when mixed with an organic solvent or replaced with a solvent, no gelation or precipitation occurs.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A titanyl sulfate solution was diluted with pure water to obtain TiO2.
An aqueous solution containing 0% by weight was obtained. While maintaining this aqueous solution at 10° C., 15% by weight aqueous ammonia was added while stirring to obtain a white slurry liquid with a pH of −9.5. This slurry was filtered and washed to obtain a cake of hydrated titanium oxide gel 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 this cake, the mixture was heated at 83° C. for 3 hours to obtain 2250 g of a 4.0 wt % titanic acid aqueous solution as T i 02. This titanic acid aqueous solution was yellowish brown and transparent and had a pH of -8.8.

Next, 626 g of a 1.6% by weight stannic acid aqueous solution (S n O2 obtained by dealkalizing a potassium stannate aqueous solution with a cation exchange resin), 2250 g of the titanic acid aqueous solution, and 6020 g of pure water were mixed. Furthermore, silica sol 94. has an average particle diameter of 7 mμ and a silica concentration of 15% by weight.
6. was mixed with the above liquid mixture, and then heated at 150°C for 18 hours. The solution was initially yellowish brown, but after 18 hours it became a pale milky blue and transparent colloidal liquid.

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

X-ray diffraction was performed using a Rigaku Denki LAD-nc model, Cu tube, 35KV, 1 after drying the sol dispersed particles at 110°C.
Measurement was performed under the condition of 2.5 mA.

This X-ray diffraction reveals that the obtained titanium oxide sol is of rutile type.

Example 2 The titanic acid aqueous solution, stannic acid aqueous solution and pure water of Example 1 were mixed, and T i O2/S n O2-2,3 (vt
/wt), (TlO+5n02) 0.5% by weight mixed aqueous solution was prepared. Thereafter, a titanium oxide sol was obtained in the same manner as in Example 1. The results are shown in Table 1 and Figure 2.

Example 3 Cation exchange resin particles were added to the titanic acid aqueous solution of Example 1 to adjust the pH to 3.8. Add 3 to this as S n 02.
A 0% by weight potassium stannate aqueous solution was diluted with T t O2/S n O2-9 (vt
/vt).

Thereafter, the cation exchange resin particles were separated, the silica sol used in Example 1 and pure water were added, and 5i02/(T10
+5n02) -0,17(vt/wt),(81
A mixed aqueous solution having a concentration of 2.0% by weight (0+TiO2+5nO2) was prepared. This was heated at 180°C for 12 hours. The solution was initially yellow-brown in color, but after 12 hours it became a clear colloidal liquid with a pale milky blue color.

Table 1 and FIG. 3 show the properties of dispersed particles of titanium oxide sol obtained by concentrating this colloidal liquid in the same manner as in Example 1.

Example 4 Titanium tetrachloride and stannic chloride were combined into TiO22/SnO2
-9 (wt/wt) Solid content (T102+5nO3)
Pure water was added to give a concentration of 4% by weight, and the mixture was mixed and dissolved. 5% by weight of aqueous ammonia was added to the solution until the pH reached 9.5, while controlling the temperature so that it did not exceed 20°C. The generated gel was washed with 0.5% by weight ammonia water and then with pure water to obtain 877.2 g of a mixed gel with a solid content concentration of 11.4%. After adding 1,429 g of 35% by weight hydrogen peroxide solution and 2,694 g of pure water, it was heated to 83°C.
Heated for 4 hours at (T 102 + S n 02 )
5 ml of a 2.0% by weight solution was obtained. This solution was yellowish brown and transparent and had a pH of 9.1.

Next, 111 g of silica sol with an average particle diameter of 5 mμ and a silica concentration of 15% by weight and the above yellow-brown transparent liquid 5 were added.
kg and 4.5 kg of pure water and heated to 17 kg at 143°C.
Heated for 2 hours. The solution was initially a yellowish brown and transparent liquid, but after 172 hours it became a pale milky bluish white transparent colloidal liquid.

The colloidal liquid thus obtained was concentrated to a solid content concentration of 24.5% by weight using an ultramembrane to obtain a stable titanium oxide sol. The properties of the dispersed particles of the obtained sol are shown in Tables 1 and 4.
As shown in the figure.

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. 5.

Example 6 A titanic acid aqueous solution was prepared in the same manner as in Example 1 using a titanyl sulfate aqueous solution having a TiO□ concentration of 7.4% by weight. 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 dispersed particles of the titanium oxide sol obtained 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 an aqueous stannic acid solution having a S n 02 concentration of 0.8% by weight was used.

Comparative Example 2 A titanyl sulfate solution was diluted with pure water to obtain an aqueous solution containing 5.0% by weight of TiO2. While stirring this aqueous solution, 15% ammonia water was added to obtain a white slurry with a pH of 9.5. The liquid temperature during the addition was about 40°C. This slurry was filtered and washed to obtain a cake of hydrated titanium oxide gel having a solid content concentration of 15.1% by weight.

After adding 771 g of 35% hydrogen peroxide solution and 883 g of pure water to 596 g of this cake, the mixture was heated at 83°C for 3 hours, and T
2250 g of 4.0% by weight titanic acid aqueous solution as iO2
I got it. This titanic acid aqueous solution is yellowish-brown and transparent with a pH of -8.
,7.

Add cation exchange resin particles to this titanic acid aqueous solution and p
It was set as H3.8. The subsequent operations and conditions were the same as in Example 3 to obtain a titanium oxide sol.

Comparative Example 3 In Example 3, TiO22/SnO2-1 (vt/
wt) except that potassium stannate was added.
A titanium oxide sol was obtained in the same manner as in Example 3.

The properties of the dispersed particles of titanium oxide sols obtained in Comparative Examples 1 to 3 are shown in Table 1, FIG. 7, FIG. 8, and FIG. 9.

[Brief explanation of drawings]

Figures 1 to 6 are X-ray diffraction diagrams of titanium oxide in the rutile-type titanium oxide sol obtained by the present invention, and Figures 7 to 9 are the oxidized It is an X-ray diffraction diagram of titanium.

Claims (1)

[Claims] 1. Hydrogen peroxide is added to a gel or sol of hydrated titanium oxide to dissolve the hydrated titanium oxide, and then the resulting solution is
A method for producing a rutile-type titanium oxide sol, which comprises heating in the coexistence of a tin compound in an amount of TiO_2/SnO_2=1.5 to 14 (weight ratio). 2. The method for producing a rutile-type titanium oxide sol according to claim 1, wherein the specific surface area of the hydrated titanium oxide particles present in the gel or sol is 150 m^2/g or more.