JPH11157839A - Strongly agglomerative titanium oxide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a titanium oxide excellent in ultraviolet shielding ability and giving a natural and proper whiteness without damaging the color tone of a substrate by heating and hydrolyzing a titanyl sulfate aq. solution in the presence of a nucleus and firing. SOLUTION: The titanium oxide is obtained by heating and hydrolyzing the titanyl sulfate aq. solution obtained by the reaction of an ilmenite ore with sulfuric acid in the presence of the nucleus of a titanium oxide fine crystal, filtering the resultant hydrolyzed product, washing if necessary and firing at 600-900 deg.C, preferably 600-800 deg.C. The anatase type strong agglomerative titanium oxide having 0.001-0.1.5 μm primary particle diameter, 0.6-2.0 μm secondary particle diameter and value L of 35-50 and value (b) of (-10) to 0 at the time of being used as a coating material is obtained by coating the titanium oxide with at least one kind of an organic material selected from a hydrated oxide and/or a fatty acid of Al, Si, Zr, Sn, Ti, Zn or the like at need, a silicon compound and a polyol compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a titanium oxide which gives a special color tone when formulated in paints, inks, cosmetics and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Titanium oxide is widely used as a white pigment for paints, inks, plastics, etc. due to its whiteness and high refractive index. The titanium oxide for a pigment is usually designed to have a primary particle diameter of 0.15 to 0.3 μm so that the hiding power (the ability to hide the substrate) is maximized.

In general, when expressing the particle size of fine particle powder, there are a primary particle size and a secondary particle size. Primary particles are single particles that are not crushed by substantial mechanical stress, and secondary particles refer to aggregates of primary particles.

[0004] When such fine particle powder is dispersed in a medium such as resin, oil or water and applied to paints, inks, cosmetics, etc., it is usually used after dispersing so as to be close to primary particles. In the material design, the primary particle diameter is usually set to be optimal according to the application and purpose.

[0005] The light scattering ability of the fine particle powder is a function of the particle diameter and the wavelength of light. In the case of titanium oxide, as described above, the scattering ability with respect to visible light is the maximum at a particle diameter of 0.15 to 0.3 µm. Become. That is, since the pigment titanium oxide is intended to conceal the substrate and give high whiteness, the primary particle diameter is set in this range.

On the other hand, when the primary particle diameter is smaller than this range, the opaque power deviates from the maximum particle diameter range, so that the scattering ability with respect to visible light is reduced, and thus the transparency is increased. At the same time, the ultraviolet shielding ability is increased. Primary particle size is 0.1
Those having a particle size of μm or less are called ultrafine titanium oxide, and are used for sunscreen cosmetics, ultraviolet shielding paints and the like by utilizing this property. In addition, ultrafine titanium oxide preferentially scatters blue light in visible light, so the coating film containing it has a bluish appearance. It is also used for metallic paints with various colors.

In general, when these pigment titanium oxides or ultrafine titanium oxides are applied to paints, cosmetics, etc., they are used in a state close to primary particles by mechanical dispersion as described above. Thereby, desired characteristics can be obtained according to the designed primary particle diameter.

[0008]

However, the blue tint of the ultrafine titanium oxide is often not so preferred in general, and when used as a cosmetic or an ultraviolet shielding paint, it exhibits a different color tone from that of the base material. In many cases, giving a natural appearance is a problem.

[0009] Titanium oxide for pigments is the most suitable material for completely concealing the substrate and obtaining a high whiteness, but is not suitable for utilizing the color tone and texture of the substrate.
Also, the ultraviolet shielding ability is not so high.

[0010]

The present inventors have conducted intensive studies to solve these problems and found that the primary particle diameter was 0.00
The anatase-type titanium oxide having a particle size of 1 to 0.15 μm and a secondary particle diameter of 0.6 to 2.0 μm gives a natural and appropriate white color without impairing the color tone and texture of the substrate, and has an ultraviolet shielding ability. Was completed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has a primary particle size of 0.001 to 0.001.
It is a highly cohesive titanium oxide having an anatase crystal form having a diameter of 0.15 μm and a secondary particle diameter of 0.6 to 2.0 μm. The strongly cohesive titanium oxide of the present invention is not easily disintegrated into primary particles even when mechanically dispersed under conditions usually used industrially,
Most of those that remain as secondary particles.

Since the light scattering ability is determined in a state where the titanium oxide particles are dispersed in the medium, that is, by the secondary particle diameter, if the secondary particle diameter is considerably larger than the above range, the scattering ability for visible light becomes small. Transparency is produced, and blue light is not preferentially scattered unlike ultrafine titanium oxide, so that a natural color tone without bluish feeling is provided. Further, the specific surface area is large in accordance with the primary particle diameter even in spite of the strong cohesiveness, so that the ultraviolet absorbing ability is considerably higher than when the secondary particle diameter is almost the same and the primary particle diameter is large.

In the present invention, the primary particle diameter is determined by the following method. First, 0.5 g of the powder is pulverized for 10 minutes with an Ishikawa-type stirring stirrer (manufactured by Ishikawa Factory), and a transmission electron micrograph is taken. From the photograph, the primary particle size was measured using a particle analyzer.
, Manufactured by Carl Zeiss Co., Ltd.), and the calculated weight average diameter is defined as the primary particle diameter.

Next, regarding the secondary particle size, this is the median size when the powder is dispersed in water and measured with a laser diffraction / scattering type particle size distribution analyzer LA-910 manufactured by HORIBA, Ltd. It shall be represented by Here, in order to disperse the powder in water, sodium hexametaphosphate is dissolved in ion-exchanged water to form a 1.0% aqueous solution.
17.0g with 40g of 0.5mm diameter zircon beads
Add to a 140cc glass mayonnaise bottle and disperse for 5 minutes on a paint shaker before measuring.

The particle size is determined by the above method. The strongly cohesive titanium oxide of the present invention has a primary particle size of 0.001 to 0.15 μm.
m is preferably 0.01 to 0.1 μm, and the secondary particle diameter is 0.6 to
It is characterized by being 2.0 μm. If the primary particle size is larger than the above range, it is difficult to obtain a strongly cohesive titanium oxide,
It is also not preferable from the viewpoint that the ultraviolet absorbing ability is reduced. If the primary particle size is smaller than 0.001 μm, the crystallinity of the titanium oxide is deteriorated, and the intrinsic physical properties of the titanium oxide are impaired.
On the other hand, if the secondary particle diameter is smaller than the above range, the opaque property becomes equivalent to that of the pigment titanium oxide, and the appropriate transparency and natural feeling of the strongly cohesive titanium oxide of the present invention cannot be obtained. Further, those larger than the above range are easily broken and hardly have strong cohesiveness.

The above is a general description of the characteristics of the strongly cohesive titanium oxide of the present invention. An index that expresses this characteristic more specifically and simply will be described. That is, the strongly cohesive titanium oxide of the present invention has a L value of 35 to 50 and a b value of -10 when a titanium oxide-containing coating film is prepared by the following method and measured with a color difference meter.
00.

(Method of preparing titanium oxide-containing coating film and measuring coating color) Paint preparation method Put the following ingredients into a 140 cc glass mayonnaise bottle,
Shake for 10 minutes using a paint shaker and disperse. Titanium oxide sample 10.0 g Veccosol J-524-IM-60 (*) 12.0 g Solvent (4/1 = xylol / n-butanol) 12.0 g 0.5 mm Φ Zircon beads 60.0 g (*) Dainippon Ink and Chemicals, Inc. Alkyd varnish

Beccosol is added to 34.0 g of the mill base dispersed.
12.0 g of J-524-IM-60 was added and shaken for 5 minutes using a paint shaker to stabilize.

Becozole J-524-IM-6 in 2.3 g of stabilized product
0, 20% nitrocellulose clear lacquer, DBP (di-n-butyl phthalate) and cellosolve acetate were added in the following composition, and the mixture was shaken for 5 minutes using a paint shaker to prepare a paint. Stabilized product 2.3 g Veccosol J-524-IM-60 16.9 g 20% nitrocellulose clear lacquer (**) 23.2 g DBP (di-n-butyl phthalate) 1.1 g cellosolve acetate 0.8 g (**) 20% nitro Cellulose clear lacquer was prepared by mixing the following components. 1 / 2RS nitrocellulose (***) 26.7% by weight xylol 12.2 n-butanol 9.8 ethyl acetate 25.6 butyl acetate 6.5 MIBK (methyl isobutyl ketone) 19.2 (***) nitrocellulose / isopropyl alcohol = 3/1, weight ratio

2. Coating film preparation and coating color measurement method The coating material prepared by the above method is applied to a morest chart paper with an applicator (film thickness after drying is 8 μm), and the coating film obtained by natural drying is coated on a black ground. Color is measured with a color difference meter (Suga Test Machine Co., Ltd. SM Color Computer SM-5
Color).

Compared with other materials by this method, the pigment titanium oxide has a large hiding power and a high whiteness, and thus has an L value of 50 or more, and the ultrafine titanium oxide has a b value due to the scattering of blue light. Becomes -10 or less.

In the same manner as usually used for pigmented titanium oxide or ultrafine titanium oxide, the surface of the particles is selected from the group consisting of Al, Si, Zr, Sn, Ti, and Zn by a known method. At least one hydrated oxide and / or oxide may be coated, and further, at least one organic substance selected from the group consisting of fatty acids, silicone compounds, and polyol compounds may be coated. By these surface treatments, it is possible to appropriately impart weather resistance and improve dispersibility.

Next, the present invention relates to a method for producing strongly cohesive titanium oxide, which comprises the steps of (1) heating and hydrolyzing an aqueous solution of titanyl sulfate in the presence of a nucleus;
It is characterized by comprising a step of firing at a temperature of 0 to 900 ° C.

Titanyl sulfate as a starting material can be usually produced by reacting ilmenite ore with sulfuric acid. This is called digestion in the titanium oxide industry,
Not limited to ilmenite ore, for example, hydrous titanium oxide may be digested. After diluting this product with water and removing impurities as necessary, hydrolysis is performed by heating. At this time, nuclei, which are microcrystals of titanium oxide, are added for the purpose of accelerating the hydrolysis reaction and adjusting the particle size and crystallinity.
The hydrolysis product thus obtained is filtered, optionally washed, and then calcined at 600 to 900 ° C, preferably at 600 to 800 ° C. If the sintering temperature is lower than this range, the primary particle diameter becomes small but does not cause strong aggregation. Conversely, if the sintering temperature is high, the primary particle diameter becomes too large and the titanium oxide of the present invention cannot be obtained.

Then, after crushing and sizing as required, a hydrated oxide and / or oxide such as Al, Si, Zr, Sn, Ti, Zn, etc. may be coated by a conventional method. May be coated with an organic substance such as a fatty acid, a silicone compound or a polyol compound. By these surface treatments, it is possible to appropriately impart weather resistance and improve dispersibility.

It is considered that the strong cohesiveness of the titanium oxide of the present invention is mainly derived from the above-mentioned production method.
Although the details of the mechanism of strong cohesion are not always clear, there is a state where the surface energy becomes very large at the stage of crystal growth in the hydrolysis or firing step,
At that time, it is considered that the particles are strongly aggregated.

When the highly cohesive titanium oxide of the present invention is applied to paints, cosmetics, and the like, excessive dispersion treatment breaks the cohesion and loses its original characteristics. As long as the particles are dispersed, the secondary particles are maintained, and the natural texture as described above can be given.

[0028]

Examples are shown below.

Example 1 (Preparation of Titanium Oxide) A nucleus obtained by neutralizing titanium tetrachloride with caustic soda was added to an aqueous solution of titanyl sulfate (200 g / liter as TiO ₂ ) obtained by cooking ilmenite ore. Thereafter, the resultant was hydrolyzed by heating at 110 ° C. for 3 hours to obtain an aqueous suspension containing hydrous titanium oxide. This aqueous suspension was filtered and sufficiently washed. The obtained washed cake was baked at 700 ° C. for 3 hours to obtain titanium oxide.

(Surface Treatment) The titanium oxide was made into an aqueous slurry of 200 g / liter, and aluminum sulfate and sodium hydroxide were added to coat the surface of the titanium oxide with hydrous aluminum oxide. The surface treatment amount is Al
_{It was set} to 5.0% based on TiO _{2 in} terms of ₂ O ₃ . Thereafter, the slurry was filtered and washed, and the obtained washed cake was dried at 120 ° C. for 24 hours, and pulverized to obtain an anatase-type strongly cohesive titanium oxide of the present invention (sample A).

Comparative Example 1 Titanium tetrachloride and aqueous sodium hydroxide solution (NaOH / TiO ₂ weight ratio 2.
After sufficient mixing of 0), the mixture was hydrolyzed by heating at 60 ° C. for 30 minutes to obtain an aqueous suspension containing hydrous titanium oxide. This aqueous suspension was filtered and sufficiently washed. 600 obtained washing cake
Calcination was performed at ℃ for 3 hours to obtain titanium oxide. Thereafter, surface treatment was performed in the same manner as in Example 1 to obtain a titanium oxide (sample B) as a comparative sample.

Comparative Example 2 A comparative titanium oxide powder (sample C) was obtained in the same manner as in Example 1 except that the firing temperature was changed to 950 ° C.

Comparative Example 3 Titanium oxide was obtained by reacting titanium tetrachloride vapor with oxygen in the gas phase at 1100 ° C. Thereafter, surface treatment was performed in the same manner as in Example 1 to obtain a titanium oxide (sample D) as a comparative sample.

Comparative Example 4 A nucleus obtained by neutralizing titanium tetrachloride with caustic soda was added to an aqueous solution of titanyl sulfate (200 g / liter as TiO ₂ ) obtained by digestion of ilmenite ore. The mixture was hydrolyzed by heating for an hour to obtain an aqueous suspension containing hydrous titanium oxide. This aqueous suspension is filtered,
After washing sufficiently, an aqueous caustic soda solution (NaOH / TiO ₂ weight ratio 3.3) was added to the repulp slurry while stirring, and heated at 95 ° C. for 2 hours. Next, the aqueous suspension of the treated product was filtered and sufficiently washed, and then, hydrochloric acid (HCl / TiO ₂ weight ratio: 1.3) was added to the repulp slurry while stirring, and heated at 95 ° C. for 2 hours. To prepare a titania sol.
This was fired in an electric furnace at 800 ° C. for 2 hours.
Surface treatment was carried out in the same manner as in Example 1 to obtain a comparative sample titanium oxide (sample E).

With respect to the samples A to E, the primary particle diameter, the secondary particle diameter, and the coating color (color of the coating film) were examined by the above-described methods. Table 1 shows the results. The crystal form was examined by powder X-ray diffraction.

[0036]

[Table 1]

Further, the above-mentioned paint was applied to a cellulose triacetate film, and a spectrophotometer (UV-2200 manufactured by Shimadzu Corporation) was used.
A, with an integrating sphere) at 300 nm. Table 2 shows the results.

[0038]

[Table 2]

According to Tables 1 and 2, the primary particle diameter of the present invention was 0.1%.
The highly cohesive titanium oxide having a secondary particle diameter of 0.6 μm or less (sample A) having a particle size of 0.6 μm or less has a lower L value of the coating film as compared with the pigment titanium oxide of the comparative sample (samples C and D). Low and high UV shielding ability. In addition, the b value of the coating film is higher than that of the comparative sample ultrafine titanium oxide (sample B).
That is, there is little blueness. Furthermore, even when compared with Sample E, it is found that the hiding power is low and the bluish color is small.

[0040]

As described above, the strongly cohesive titanium oxide of the present invention gives a natural and appropriate white color without impairing the color tone of the substrate, and has an ultraviolet shielding ability.
It is a very useful material for applications such as ink and cosmetics.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI A61K 7/02 A61K 7/02 N (72) Inventor Takayuki Kadowaki 1 Ishiharacho, Yokkaichi-shi, Mie Pref.

Claims (5)

[Claims] A strongly cohesive titanium oxide having a primary particle size of 0.001 to 0.15 μm, a secondary particle size of 0.6 to 2.0 μm, and an anatase crystal form. 2. The L value of the coating film is 35-50, and the b value is -1.
The strongly cohesive titanium oxide according to claim 1, wherein the number is from 0 to 0. 3. The particle surface is coated with a hydrated oxide and / or an oxide of at least one element selected from the group consisting of Al, Si, Zr, Sn, Ti, and Zn. The strongly cohesive titanium oxide according to claim 1 or 2, wherein 4. The strongly cohesive oxidation according to claim 1, wherein the surface is coated with at least one organic substance selected from the group consisting of a fatty acid, a silicone compound, and a polyol compound. Titanium. 5. A step of (1) heating and hydrolyzing an aqueous solution of titanyl sulfate in the presence of a nucleus;
The method for producing strongly cohesive titanium oxide according to claim 1, comprising a step of firing at a temperature of 0 to 900 ° C.