JP3537466B2 - Fine powder of titanium dioxide and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] INDUSTRIAL FIELD The present invention is zirconium having excellent dispersibility and light resistance
Aluminum solid solution anatase type titanium dioxide fine powder, more specifically, food packaging materials, ultraviolet ray deterioration inhibitor,
The present invention relates to an easily dispersible zirconium / aluminum solid solution anatase-type titanium dioxide fine powder useful for ultraviolet ray shielding sheets and films, sunscreen cosmetics and the like.

2. Description of the Related Art Titanium dioxide fine powder having a particle size of 0.1 μm or less, for example, transmits visible light when blended with a resin, while blocking ultraviolet rays to protect substances which are discolored or deteriorated by the ultraviolet rays. Therefore, it is used for plastics packaging materials for foods and pharmaceuticals, plastics coating materials for agriculture and horticulture, cosmetics, and the like. Since such titanium dioxide fine powder is fine particles, it has a very strong cohesive force and is difficult to disperse in a resin. Therefore, since the undispersed aggregated particles remain in the dispersion medium resin when added to and mixed with the resin, the original visible light high transmittance and ultraviolet shielding ability of the titanium dioxide fine powder having the above-described size are substantially achieved. The fact is that it is not available. Further, the fine powder of titanium dioxide having the above-mentioned size has a problem of oxidizing and deteriorating the dispersion medium resin due to strong photoactivity.

In order to solve the above problems, a method has been proposed in which the surface of titanium dioxide is coated to improve the dispersibility. For example, Japanese Patent Publication No. 63-51974 discloses a fine powdered titanium dioxide composition which has improved the above-mentioned problems. The fine titanium dioxide particles having a size substantially in the range of 0.01 to 0.1 [mu] m are coated with silicon and ( Or) a titanium dioxide composition treated with an oxide of aluminum. Japanese Patent Application Laid-Open No. 2-194603 discloses a fine particle titanium dioxide powder having excellent dispersibility and weather resistance. ₂ to 0.1 to 5% tin hydrated oxide and / or ZrO
₂ as 0.1% to 5% of zirconium hydrous oxide of coated as the innermost layer, then the SiO ₂ by weight of the fine particulate titanium dioxide 0.1 to 8% silicon oxide hydroxide of the intermediate layer It discloses a fine particle titanium dioxide powder which is coated and finally coated on the outermost layer with a hydrated oxide of 0.1 to 10% as Al ₂ O _{3 with} respect to the weight of the particle titanium dioxide.

There are several other applications for improving the dispersibility by surface treatment. In each case, when providing a coating layer on the surface of the titanium dioxide powder, first disperse the titanium dioxide fine powder into primary particles. It is necessary to make it. However, conventional titanium dioxide fine powder has a problem in dispersibility in water, and the operation itself of dispersing titanium dioxide into primary particles is difficult, and therefore, titanium dioxide fine powder with excellent dispersibility is industrially produced stably. It was difficult to do.

[0005] Regarding the production of zirconium solid solution titanium dioxide fine particles, Suyama et al. Reported that they could be synthesized by a gas phase method (Y. Suyama, M. Tanak).
a, A. Kato: Ceramurgia Inter
n. , Vol. 5, No. 2, pp. 84-88 (19
79)). However, the zirconium-dissolved titanium dioxide fine particles synthesized by them contain a mixture of coarse particles having a size of 0.3 μm or more, and are inferior in high visible light transmission ability and ultraviolet shielding ability. Incidentally, there is no report of anatase type titanium dioxide fine powder in which zirconium and aluminum are simultaneously dissolved.

As described above, the conventional fine titanium dioxide powder has problems such as poor dispersibility, strong photoactivity, and it is not easy to provide a coating in an industrially stable manner. Was. Therefore, there has been a demand for a novel titanium dioxide fine powder which has excellent dispersibility and light resistance and can be easily and stably manufactured industrially. In addition, there was no synthesis example of titanium dioxide fine powder having an anatase structure in which zirconium and aluminum were dissolved.

It is an object of the present invention to provide a novel titanium dioxide fine powder having an anatase structure in which zirconium and aluminum are dissolved as a solid solution, which has the above-mentioned disadvantages of the fine titanium dioxide powder, and a method for producing the same.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, by dissolving zirconium and aluminum in titanium dioxide fine powder having an anatase structure,
The inventors have found that the dispersibility and light fastness are improved, and completed the present invention. That is, the present invention provides an anatase-type titanium dioxide fine powder having a size in the range of 0.005 to 0.1 μm and having zirconium and aluminum dissolved in the crystal structure. . Further, the present invention provides the titanium dioxide fine powder having a coating layer on the particle surface, preferably a coating layer of at least one hydrated oxide selected from the group consisting of hydrated oxides of silicon and hydrated oxide of aluminum. To provide.

The method for producing the above titanium dioxide particles is to add a water-soluble zirconium compound and a water-soluble aluminum compound to the titania sol, add an alkali to neutralize the mixture, wash with filtered water, and then bake at 700 to 1000 ° C. . When a coating layer of silicon and / or aluminum is further provided, after firing, the fired product is dispersed in water to form an aqueous slurry, which is water-soluble in the slurry and is selected from the group consisting of silicon compounds and aluminum compounds. After adding at least one compound, neutralization may be performed.

[0010] The amount of zirconium and aluminum, preferably 0.5 to 25% by weight with respect to TiO _2, respectively as ZrO _2, preferably 1-15 wt%, Al
0.5 to 10% by weight, preferably 1 to 7% by weight as ₂ O ₃ is suitable. If the addition ratio of ZrO ₂ is less than this range, it is difficult to obtain the effect of improving dispersibility and light fastness. If the addition ratio is too large, there is no particular difference in light fastness, but the dispersibility is poor. . Al ₂ O ₃ has an effect of preventing grain growth and transition from anatase to rutile. Therefore, if the addition ratio of Al ₂ O ₃ is less than this range, it becomes difficult to industrially produce fine powder having an anatase structure having a small particle diameter, and if the addition ratio is too large, ultraviolet rays are blocked. This is not preferable because the effect is reduced.

The fine powder according to the present invention has a particle size of 0.005.
で あ れ ば 0.1 μm, but 0.005
A range of 0.05 μm is more preferable.

Although rutile type ultrafine powder has been known, there is a problem that its use is limited due to its high price. The present invention has found that even anatase-type titanium dioxide, which is generally inferior to rutile-type in light resistance, can obtain sufficiently satisfactory light resistance by dissolving zirconium and aluminum in a solid solution. It has great significance in providing the material of the above.

The zirconium-aluminum solid solution titanium dioxide fine powder of the present invention is excellent in dispersibility and dispersion stability in water, so that it can be easily mixed with various water-soluble resins to form a coating film. It is easy to disperse and mix into the base for use or other cosmetic ingredients. Furthermore, since it does not substantially contain coarse agglomerated particles, paints, viscosity modifiers for plastics, silicone rubber fillers for preventing deterioration in physical properties at high temperatures,
It can be suitably used as a surface coating agent such as a pigment and a toner, a frost color pigment of an aluminum metallic paint, a solid lubricant such as a fiber and a film, and the like. In particular, it has a good affinity for urethane and has a low photoactivity compared to conventional titanium dioxide, so that it is suitably used for polyurethane elastic fibers which are considered to be weak against ultraviolet rays.

Further, the fine powder of titanium dioxide having an anatase structure in which zirconium and aluminum are dissolved in the present invention is excellent in dispersibility in water and can be easily dispersed in primary particles. Surface treatment with hydrated oxides and the like for improvement can be easily and uniformly performed, and has excellent dispersibility and light resistance in resin.
Fine powder having a coating layer on the surface can be industrially easily and stably produced.

The zirconium-aluminum solid solution anatase type titanium dioxide fine powder of the present invention is typically produced by the following method. That is, a titania sol obtained by washing and coagulating a precipitate formed by heating and hydrolyzing an aqueous titanyl sulfate solution, or a titania sol obtained by heating and hydrolyzing an aqueous hydrochloric acid solution of titanium, After addition of a zirconium compound and a water-soluble aluminum compound, neutralization was performed by adding an alkali, followed by washing, drying,
What is necessary is just to bake.

The titania fine particles, which are components of the titania sol, mean hydrous titanium oxide, and in the present invention, those having an amorphous or anatase type structure are used. The titania sol from the coagulated precipitate generated by heating and hydrolyzing the aqueous solution of titanyl sulfate is made into a slurry after washing the coagulated precipitate, neutralized with an alkali such as aqueous sodium hydroxide solution or aqueous ammonia, filtered and washed. Remove sulfate groups. Thereafter, the slurry is slurried, and a monobasic acid such as hydrochloric acid or nitric acid is added to adjust the pH of the slurry to 3 or less, preferably to 2
It is obtained by adjusting to 調整 1 and peptizing. Further, the titania sol from the coagulated precipitate generated by heating and hydrolyzing an aqueous hydrochloric acid solution of titanium is filtered, washed, slurried, and a monobasic acid such as hydrochloric acid or nitric acid is added, and the slurry is p-pulped.
It is easily obtained by adjusting H to 3 or less, preferably 2-1.

The water-soluble zirconium compound to be added to the titania sol includes zirconium oxychloride, zirconium chloride and zirconium sulfate, and the water-soluble aluminum compound includes aluminum chloride, polyaluminum chloride, aluminum sulfate, sodium aluminate and the like. is there.

When the zirconium compound or the aluminum compound is added, the concentration of the titania sol is 50 to 250 g / l as TiO ₂ , preferably 80 to 200 g / l. It is preferable that the amounts of the zirconium compound and the aluminum compound be adjusted so that the amounts of zirconium and aluminum in the produced titanium dioxide are within the above-mentioned preferred ranges.

It is not necessary for all of the added zirconium and aluminum to be present in the crystal lattice of titanium dioxide, and a part of the added zirconium and aluminum is made of zirconium titanate (ZrTiO ₄ ) Zirconium, aluminum titanate, amorphous aluminum oxide, and the like may be present at the same time.

The firing temperature is in the range of 700 to 1000 ° C.
Preferably, the range of 800 to 950 ° C. is appropriate. That is, if the firing temperature is lower than this range, the amount of adsorbed water increases, which has an unfavorable effect such as difficulty in dispersing when mixed with the resin. On the other hand, if the height is increased, the titanium dioxide particles adhere to each other or sinter to generate coarse particles larger than 0.1 μm, which is not preferable.

Although the titanium dioxide of the present invention is produced by the above method, a small amount of rutile-type crystals may be produced depending on the firing temperature. It goes without saying that rutile-type crystals can be contained within a range that does not impair the effects of the present invention, but it is desirable that the proportion of rutile-type crystals is about 10% by weight or less. Further, by mixing titania fine particles having a rutile structure in the starting material, a mixture of anatase-type titanium dioxide fine particles and rutile-type titanium dioxide fine particles can be produced, and the obtained anatase-type titanium dioxide fine particles can be produced. May be used in combination with rutile-type titanium dioxide fine particles. In these cases, it is needless to say that both can be mixed in an arbitrary ratio according to desired characteristics.

Although the zirconium-aluminum solid solution anatase type titanium dioxide fine powder of the present invention is excellent in water dispersibility, the dispersibility and dispersion stability in a coating material are compatible with a dispersion medium resin and a solvent. This causes a problem, and a problem may occur in dispersion stability depending on the type of the resin or the solvent. In such a case, it is preferable to improve the familiarity by coating the particle surface with a hydrated oxide of silicon or aluminum by a known method. The zirconium of the present invention
Since the aluminum-dissolved titanium dioxide fine powder is excellent in water dispersibility, such coating treatment is particularly effectively utilized. The type of the coating material is not particularly limited, and it can be treated with a known substance according to the type of the resin or the solvent used. For example, the above-described treatment with silicon and / or aluminum oxide may be performed, or the innermost layer may be coated with a hydrated oxide of tin and / or hydrated oxide of zirconium, and then the hydrated oxide of silicon may be interposed. The layer may be coated and finally coated with a hydrated aluminum oxide. In addition, it can be coated with a hydrated oxide such as titanium, cerium or zinc. Furthermore, known organic coating materials such as surfactants such as aluminum stearate, dodecylbenzenesulfonic acid, and alkanolamine, polyhydric alcohols, organosiloxane compounds, silane-based, titanate-based, and aluminum-based coupling agents are also used. it can. Generally, silicon and / or
Alternatively, treatment with a hydrated oxide of aluminum is suitably performed.

This coating treatment can be performed by a known method. For example, when the treatment is performed with a hydrated oxide of silicon and / or aluminum, the zirconium-aluminum solid solution titanium dioxide obtained in the above-mentioned calcination step is converted to 100 to 400 g / l, preferably 2 to ₂ as TiO 2.
It is made by dispersing in water so as to have a concentration of 00 to 300 g / l to form an aqueous slurry, adding a water-soluble silicate or aluminum compound thereto, and then adding an alkali or acid to neutralize the slurry. For example, when sodium silicate is used as a water-soluble silicate, an acid such as sulfuric acid, hydrochloric acid, nitric acid or the like is added to the aqueous slurry, and p
Adjust H to 7. Also, for example, when aluminum sulfate is used as the water-soluble aluminum compound,
The pH of the aqueous slurry in which zirconium / aluminum solid solution titanium dioxide is dispersed is adjusted to 7 by adding an alkali such as sodium hydroxide or potassium hydroxide.

The treatment amount of the hydrated oxide of silicon or aluminum is suitably 1 to 20% by weight based on TiO ₂ in terms of SiO ₂ and Al ₂ O ₃ , respectively. If the treatment amount is less than this, a sufficient dispersibility improving effect cannot be obtained, and if the treatment amount is too large, the ultraviolet shielding effect is undesirably reduced.

Further, a treatment method using an organic coating material is also known, and the treatment can be performed by an appropriate method as needed.

The titania sol synthesized from naturally occurring ores such as rutile-type titanium oxide and ilmenite as a TiO ₂ source contains various impurities derived from ores such as niobium, tantalum and iron. There is no problem even if it contains an amount acceptable for pigment use.

Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are provided for illustrative purposes only, and are not intended to limit the scope of the invention.

Example 1 Hydrous titanium oxide obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with pure water until the supernatant had an electric conductivity of 1100 μS / cm, and then an aqueous solution of sodium hydroxide was added. The pH of the slurry was adjusted to 9 and stirring was continued for 1 hour. Thereafter, hydrochloric acid was added dropwise to adjust the pH of the slurry to 7, and the electric conductivity of the supernatant was 250 μS / cm.
The substrate was washed with pure water until the temperature became.

Thereafter, hydrochloric acid was added to the slurry to adjust the pH of the slurry to 1.0, followed by stirring for 15 hours.
One liter of a titania sol having an anatase crystal structure of 130 g / l was obtained as iO ₂ . 48 g of 240 g / l zirconium oxychloride aqueous solution as ZrO ₂
After the addition of l, 60 ml of 100 g / l polyaluminum chloride as Al ₂ O ₃ was added, and the mixture was stirred for 1 hour. Thereafter, an aqueous solution of sodium hydroxide is added, and the p
H was adjusted to 7. The electric conductivity of the supernatant is 60 μS /
cm, washed with pure water, filtered and dried. The dried product is calcined at 900 ° C. for 1 hour to obtain a mixture of 0.007 to 0.
A fine powder having a particle size of 02 μm was obtained.

When this fine powder was examined by X-ray diffraction, it showed a diffraction pattern similar to that of the anatase type titanium dioxide, but the position of the diffraction line was shifted to a lower angle side than that of the anatase type titanium dioxide. . The lattice spacing d corresponding to the (101) plane of the anatase-type titanium dioxide was determined to be 3.528 ° using high-purity silicon powder (99.9%) as an internal standard.

Comparative Example 1 An aqueous solution of sodium hydroxide was added to 1 liter of the titania sol used in Example 1 to adjust the pH of the slurry to 7. The supernatant was washed with pure water until the electric conductivity of the supernatant became 60 μS / cm, then filtered and dried. 9
When fired at 00 ° C. for 1 hour, 0.04 to 0.19 μm
A fine powder having a particle size of m was obtained.

When this fine powder was examined by X-ray diffraction, two powders of rutile-type titanium dioxide and anatase-type titanium dioxide were obtained.
It was a phase mixture. Rutile titanium dioxide (110)
Plane diffraction intensity and anatase type titanium dioxide (101)
The quantitative ratio of these two phases was determined from the ratio to the diffraction intensity of the surface. As a result, about 85% by weight of rutile type titanium dioxide and about 15% by weight of anatase type titanium dioxide were obtained.

The anatase-type titanium dioxide (101) was prepared using high-purity silicon powder (99.9%) as an internal standard.
The lattice spacing d was determined to be 3.521 °.

Comparative Example 2 ZrO ₂ was added to 1 liter of the titania sol used in Example 1.
After adding 48 ml of 240 g / l aqueous solution of zirconium oxychloride, the mixture was stirred for 1 hour. Then, the pH of the slurry was adjusted to 7 by adding an aqueous sodium hydroxide solution. The supernatant was washed with pure water until the electric conductivity of the supernatant became 60 μS / cm, then filtered and dried. This dried product is 90
The powder was fired at 0 ° C. for 1 hour to obtain a fine powder having a particle size of 0.02 to 0.05 μm.

When this fine powder was examined by X-ray diffraction, it was found to be a two-phase mixture of rutile-type titanium dioxide and anatase-type titanium dioxide. Rutile titanium dioxide (11
0) plane diffraction intensity and (10)
1) When the quantitative ratio of these two phases was determined from the ratio to the diffraction intensity of the plane, the rutile type titanium dioxide was about 10% by weight,
The anatase type titanium dioxide was about 90% by weight.

Incidentally, both diffraction lines were shifted to lower angles than the original positions of the diffraction lines of titanium dioxide.
The lattice spacing d corresponding to the (101) plane of the anatase-type titanium dioxide was determined to be 3.534 ° using high-purity silicon powder (99.9%) as an internal standard.

From the comparison of the measured values of the (101) lattice spacing d of the anatase of the above-mentioned Example and Comparative Example, the fine powder of Example 1 shows that Zr ⁴⁺ and Al ³⁺ have a crystal lattice of anatase-type titanium dioxide. It can be seen that the crystal is a solid solution substituted with Ti ⁴⁺ in the solid.

COMPARATIVE EXAMPLE 3 The same procedure as in Comparative Example 1 was carried out except that the firing conditions were changed to 750 ° C. for 1 hour.
A fine powder of anatase-type titanium dioxide having a particle diameter of 0.01 to 0.05 μm was obtained.

Example 2 200 g of the fine powder obtained in Example 1 was made into a 150 g / l aqueous slurry, and 30 ml of a 200 g / l sodium aluminate aqueous solution was added as Al ₂ O ₃ , and hydrochloric acid was added dropwise. The pH of the slurry was adjusted to 6.5. filtration,
Washed and dried at 110 ° C.

Example 3 400 g of the fine powder obtained in Example 1 was converted into an aqueous slurry of 200 g / l, and after adding 290 ml of 85 g / l sodium silicate aqueous solution as SiO ₂ , 107 g / l as Al ₂ O ₃ was further added. 243m of aluminum sulfate aqueous solution
1 was added. An aqueous solution of sodium hydroxide was added dropwise to the slurry to adjust the pH to 7.5. Filter and wash 110
Dried at ° C.

When the fine powders obtained in Examples 1 to 3 and Comparative Examples 1 and 3 were exposed to sunlight for 8 hours, the color tone of each of the fine powders of Comparative Example turned blue-black, whereas That of the fine powder did not particularly change color.

The fine powders of Example 1 and Comparative Examples 1 and 3 were dispersed in water to a concentration of 0.01% by weight.
Table 1 shows the results of measuring the transmittance of visible light (550 nm) and ultraviolet light (320 nm) with a spectrophotometer Ubest-50 manufactured by JASCO Corporation in a quartz cell having a thickness of 0 mm. From this table, it can be seen that the dispersion of the fine powder of the present invention has a high visible light transmittance. Example 1
The properties of the dispersion of Comparative Example 3 were measured after the dispersion of Comparative Example 3 was left for 3 days. The powder was not particularly changed, and had excellent dispersion stability in water.

When the fine powders of Examples 2 and 3 were blended into a nitrocellulose solution to prepare a nitrocellulose paint, the paint was examined every 5 minutes with a grind gauge.
The dispersion time until it becomes 0 μm or less is 15-20.
Min and excellent in dispersibility.

[0044]

[Table 1]

Continuation of the front page (56) References JP-A-63-95152 (JP, A) JP-A-2-212315 (JP, A) JP-A-61-201604 (JP, A) JP-B-63-51974 (JP) , B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01G 23/00

Claims (5)

(57) [Claims] 1. Anatase-type titanium dioxide fine powder having a size in the range of 0.005 to 0.1 μm, wherein zirconium and aluminum are dissolved in the crystal structure. 2. The fine titanium dioxide powder according to claim 1, having a coating layer on the particle surface. 3. The fine titanium dioxide powder according to claim 2, wherein the coating layer is at least one hydrated oxide selected from the group consisting of a hydrated oxide of silicon and a hydrated oxide of aluminum. 4. After adding a water-soluble zirconium compound and a water-soluble aluminum compound to the titania sol, neutralize by adding an alkali, and filter and wash with water.
The method for producing fine titanium dioxide powder according to claim 1, wherein the powder is fired at 0 ° C. 5. A water-soluble zirconium compound and a water-soluble aluminum compound are added to the titania sol, neutralized by adding an alkali, and filtered and washed with water.
After firing at 0 ° C., the fired product is dispersed in water to form an aqueous slurry, and water-soluble, at least one compound selected from the group consisting of silicon compounds and aluminum compounds is added to the slurry, followed by neutralization. The method for producing fine titanium dioxide powder according to claim 3, wherein