JP3422832B2 - Dendritic or starfish-shaped fine titanium dioxide and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a particulate dendritic or starfish-shaped titanium dioxide and a method for producing the same, and a dendritic or starfish-shaped particulate titanium dioxide prepared by applying a conductive treatment. The present invention relates to fine particle titanium dioxide and a method for producing the same, as an ultraviolet ray preventive or shielding agent for sunscreen cosmetics, ultraviolet protective coatings, plastics, etc., and also as a conductivity imparting agent or charging agent for plastics, coatings, rubber, fibers, etc. It is useful as an inhibitor, and also as a conductivity-imparting agent for a support of a recording material such as electrophotographic copying paper and electrostatic recording paper, or a substrate thereof.

[0002]

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION The primary particle size is 0.1.
Titanium oxide particles with a particle size of less than μm show transparency because they transmit visible light when compounded into resin film or molded product, while exhibiting transparency while protecting substances that are discolored or deteriorated by ultraviolet rays. , The primary particle size is about 0.
Since it exhibits useful properties different from pigment grade titanium oxide having a particle size of 15 to 0.5 μm, it is being used as an ultraviolet ray preventive or shielding agent for sunscreen cosmetics, ultraviolet ray preventive paints, plastics and the like.

[0003]

By the way, the transparency and the ultraviolet ray shielding property of the fine particle titanium oxide are increased in inverse proportion to the particle size, whereas the ultraviolet ray shielding property is in a certain particle size range. Shows the maximum value, and the ultraviolet ray shielding property is lowered regardless of whether the particle diameter is large or small outside the above range. Therefore, there is a demand for the appearance of fine particle titanium oxide which satisfies both transparency and ultraviolet ray shielding property at the same time.

As a method for producing fine particle titanium oxide having an average particle diameter of the primary particles of about 0.05 to 0.1 μm, for example, it is obtained by hydrolyzing a titanyl sulfate solution or titanium tetrachloride solution. Another method is to bake the titania sol of hydrous titanium oxide or the titania sol obtained by treating the hydrous titanium oxide with caustic alkali and then heat-treating it in the presence of hydrochloric acid. However, particle sintering is likely to occur remarkably in the firing process, which makes it difficult to disperse even the primary particles substantially in various application medium systems, and as a result, a sufficient ultraviolet shielding effect may be brought about. First, the improvement is strongly desired.

Further, as the conductivity-imparting agent of the titanium oxide type compound, spherical titanium oxide powder or spherical conductive titanium oxide powder based on spherical fine particles of titanium oxide powder,
A conductive substance containing fibrous potassium titanate as a main component,
Needle-like conductive titanium oxide based on high-quality needle-like titanium oxide having a length of 1 to 10 μm has been proposed.

The titanium oxide-based conductivity-imparting agent has a needle-like (including fibrous) or rod-like shape rather than a spherical shape, and has a smaller powder resistance value of itself,
That is, as the conductivity is higher, a desired conductive resin product, rubber product or the like can be obtained even if the compounding ratio of the resin, rubber or the like to the medium is reduced. The spherical conductive titanium oxide powder,
The powder resistance of itself is 1 to 10 Ωcm, which shows extremely excellent conductivity. However, since it is a spherical powder, it is mixed with a medium such as resin or rubber to obtain a predetermined conductivity. For application, it is generally necessary to incorporate fairly large amounts of powder into the medium. For this reason, the strength of products such as conductive resin and conductive rubber is reduced, and it is not economical. Further, although the electroconductive substance has no problem in terms of shape, it has a drawback that it has a high powder resistance value and is easily broken during dispersion.
Further, the needle-shaped conductive titanium oxide has solved the above-mentioned problems, and shows very excellent conductivity even if it is added in a small amount to the medium, but the shape is needle-shaped. However, because of its long length, when it is added to a medium to form a conductive composition such as paint, there is a problem in terms of surface smoothness of the coating film of the composition. In addition, as an antistatic agent for magnetic recording media, together with the increase in recording density, the effect of imparting conductivity,
There is a demand for a material having further excellent transparency and surface smoothness of the magnetic layer.

[0007]

As a result of various studies to solve the above problems, the present inventors have found that a specific length, a specific thickness and a specific specific surface area obtained under specific conditions are obtained. In addition to having excellent ultraviolet shielding properties, the specific shape of the titanium dioxide fine particles has excellent transparency and surface smoothness in the application system, and further, the titanium dioxide fine particles are used as a substrate for conductivity. The material which has been subjected to the imparting treatment has extremely excellent performance as a conductivity imparting agent, and the present invention has been completed based on the knowledge that the scope of application of its application can be greatly expanded.

That is, according to the present invention, 1) the length is 0.2 to 0.5.
dendritic or starfish-shaped fine particle titanium dioxide having a thickness of 0.05 to 0.1 μm and a specific surface area of 70 to 130 m ² / g, 2) aluminum, silicon on the particle surface, The dendritic or starfish-like fine particle titanium dioxide according to the above 1) having a coating of a hydrous oxide or oxide of at least one element selected from the group of titanium, zirconium, tin and antimony, 3) containing antimony on the particle surface 1) The dendritic or starfish-shaped fine particle conductive titanium dioxide according to 1), which has a conductive layer made of tin oxide or tin-containing indium oxide, 4) treated the hydrous titanium oxide with an alkali, and then obtained the reaction product and hydrochloric acid. 1 to 1 mol of titanium oxide of the reaction product
The reaction was carried out under instantaneous mixing at a ratio of 4 mol, and then 85 ° C.
A dendritic or starfish that is aged by heating as described above, has a length of 0.2 to 0.5 μm, a thickness of 0.05 to 0.1 μm, and a specific surface area of 70 to 130 m ² / g. 5) A method for producing particulate titanium dioxide, 5) A slurry of the dendritic or starfish particulate titanium dioxide obtained by the method of 4) above is prepared from a group of water-soluble salts of aluminum, silicon, titanium, zirconium, tin and antimony. The method for producing dendritic or starfish-shaped fine particle titanium dioxide, which comprises adding at least one selected and neutralizing to coat the surface of the fine particle titanium dioxide particles with a hydrous oxide or oxide of said element, 6) above 3) A conductive composition containing dendritic or starfish-shaped fine particles of titanium dioxide, 7) A sunscreen cosmetic containing the dendritic or starfish-shaped fine particles of titanium dioxide of 8), UV protection paint containing the dendritic or starfish particulate titanium dioxide of item 1) or 2), and 9) UV protection plastics composition containing the dendritic or starfish particulate titanium dioxide of 1) or 2) above. Is.

As is clear from the drawings (electron micrographs), the dendritic or starfish-shaped fine particles of titanium dioxide of the present invention form needle-shaped or rod-shaped constituent particles that are aggregated and combined to form a bundle-shaped product. , And those bundles that are radially combined to form a single particle, which are conventional needle-shaped,
It shows a dendritic or starfish-like shape which is completely different from the rod-like or spherical shape. The length of the dendritic or starfish-shaped particulate titanium dioxide of the present invention having such a shape indicates the longest portion of each single particle, and the thickness thereof is the short axis of the bundle-like material constituting the longest portion. The dendritic or starfish particulate titanium dioxide of the present invention has a length of 0.2 to 0.5 μm and a thickness of 0.
It is 05 to 0.1 μm. Specific surface area is 70-130m
A ² / g, preferably 70m ² / g~100m ² /
It is g.

The dendritic or starfish-shaped fine particle titanium dioxide of the present invention is useful for various sunscreen cosmetics, UV-preventive paints, and UV-preventive plastics compositions. Hydrous oxides of metals such as silicon, titanium, zirconium, tin and antimony can be precipitated and coated to further improve the dispersibility of the titanium dioxide in a dispersion medium, light resistance and the like. The amount of the hydrous oxide or oxide of the metal to be coated is 1 to 100% by weight in terms of the total oxide conversion of the metal with respect to titanium oxide.

The dendritic or starfish particulate titanium dioxide of the present invention, which is obtained by subjecting the dendritic or starfish particulate titanium dioxide to a conductive treatment, is blended with plastics, rubber, fibers or the like as a conductivity-imparting material or substrate. , Conductive plastics, conductive paint, magnetic paint, conductive rubber,
It can be used as a conductive composition such as a conductive fiber. The conductive treatment forms a conductive layer made of antimony-containing tin oxide or tin-containing indium oxide on the particle surface of the dendritic or starfish-shaped fine particle titanium dioxide. In order to form a conductive layer, for example, a water-soluble tin compound and a water-soluble antimony compound are added to the fine titanium dioxide particles, and a tin hydroxide and an antimony hydroxide are deposited on the surface of the titanium oxide particles. After that, it is fired, and a conductive layer made of antimony-containing tin oxide is applied to manufacture. In this case, the amount of tin oxide is Sn
O ₂ is 10 to 150% by weight, preferably 30 to 10%
It is 0% by weight. If it is less than this range, it becomes difficult to form a continuous conductive layer, and desired conductivity cannot be obtained. If it is too large, improvement in conductivity corresponding to the increase in amount cannot be expected, so that it is not economical. The amount of the antimony oxide in the conductive layer is Sb _{2 with} respect to the tin oxide (SnO ₂ ).
O ₃ as 5 to 40 wt% preferably 10-30 wt%
Is. If it is less than this range, it becomes difficult to obtain the desired conductivity, and if it is too large, the conductivity is lowered and the coloring due to antimony oxide becomes strong, which is not desirable.

Next, the method for producing the dendritic or starfish-shaped fine particle titanium dioxide of the present invention will be described. First, an alkali is added to the hydrous titanium oxide aqueous suspension, and then 90 to 1
The reaction product is obtained by heat treatment at a temperature of 00 ° C., and then the pH is adjusted to neutral as necessary to perform solid-liquid separation, and the solid content is washed with water. Examples of the alkali used in the alkali treatment include sodium hydroxide and sodium carbonate, but it is preferable to use an aqueous solution of sodium hydroxide. The solid content washed with water is suspended in water to obtain a suspension, and the suspension and hydrochloric acid are mixed at a ratio of 1 to 4 mol of hydrochloric acid to 1 mol of titanium oxide in the suspension. While adding, both are instantly added and mixed to react. More specifically, for example, 1 to 4 mol of hydrochloric acid is added at a rapid rate of 2 mol / sec at the latest to 1 mol of titanium oxide as the reaction product in the suspension. Further, the suspension and hydrochloric acid may be added and mixed in the above ratio instantaneously and simultaneously, or the suspension may be instantaneously added and mixed in hydrochloric acid in the above ratio.
Then, it is heat-aged at a temperature of 85 to 100 ° C., preferably 90 to 100 ° C. for 1 hour or more to obtain an aqueous suspension of dendritic or starfish-shaped fine particles of titanium dioxide, which is filtered, washed and dried to obtain a powder. .

Examples of the hydrous titanium oxide, which is a titanium source of the dendritic or starfish-shaped fine particles of titanium dioxide, include those obtained by hydrolysis or neutralization hydrolysis of a titanyl sulfate solution or a titanium tetrachloride solution. More specifically, for example, while keeping an aqueous solution of titanium tetrachloride at room temperature, it is neutralized with an aqueous solution of sodium hydroxide to precipitate colloidal amorphous titanium hydroxide, and the colloidal titanium hydroxide is aged by heating. The resulting rutile-type microtitania sol can be used.

On the particle surface of the dendritic or starfish-shaped fine particles of titanium dioxide obtained as described above, aluminum,
Hydrous oxides or oxides of metals such as silicon, titanium, zirconium, tin and antimony may be precipitated and coated. In this method, for example, dendritic or starfish-shaped fine particle titanium dioxide is dispersed in water to form a slurry, and if necessary, wet pulverization and classification treatment are performed, and then aluminum, silicon, titanium, zirconium, tin, and antimony are added to each of them. At least one selected from the group of water-soluble salts is 1 to 100% by weight in terms of total oxide equivalent to titanium oxide.
After the addition, when the water-soluble salt is alkaline in the slurry, an acidic solution such as sulfuric acid or hydrochloric acid is used. When the water-soluble salt is acidic in the slurry, an alkaline aqueous solution such as sodium hydroxide or ammonia water is used. It can be carried out by precipitating and coating on the surface of the titanium oxide particles by mixing, separating the particles, drying and crushing. This coating treatment can improve the dispersibility, durability, etc. of the dendritic or starfish-shaped fine particle titanium dioxide in the dispersion medium.

The dendritic or starfish-like fine particle titanium dioxide of the present invention is useful for various sunscreen cosmetics, UV-preventive paints, and UV-preventive plastics compositions, as described above, and also has electrical conductivity. The treated dendritic or starfish-shaped fine particles conductive titanium dioxide is compounded into plastics, rubber, fibers, etc. as a conductivity-imparting material or substrate, and is used as a conductive plastics, conductive paint, magnetic paint, conductive rubber, It can be used as a conductive composition such as a conductive fiber.

When the dendritic or starfish-like fine particle titanium dioxide of the present invention is used as a sunscreen cosmetic, for example, an oily component, a moisturizer, a surfactant, a pigment, a fragrance, a preservative, water, alcohols, an additive, etc. It can be used in various forms such as lotions, creams, pastes, sticks, and emulsions by mixing with a sticky agent and the like.

When it is used as ultraviolet protection plastics or conductive plastics, for example, vinyl chloride resin, ABS resin, polyethylene, polypropylene,
Vinylidene chloride, polystyrene, polycarbonate, nylon, EVA resin, polyacetal resin, polyamide resin, phenol resin, melamine resin, acrylic resin,
It is mixed with synthetic resins such as polyester resin, urea resin, silicone resin, and fluororesin.

When used as a coating for preventing ultraviolet rays, a conductive coating, or a magnetic coating, for example, polyvinyl alcohol resin, vinyl chloride-vinyl acetate resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, polyester resin, ethylene vinyl acetate. It is mixed with a copolymer, an acrylic-styrene copolymer, a fibrin resin, a phenol resin, an amino resin, etc., and dispersed in water or a solvent. In the case of a conductive coating, the coating is applied to an insulating substrate such as paper or a polymer film to form a conductive coating film having a light weight and excellent adhesion on the substrate to form an electrostatic recording paper. , Electrophotographic copy paper, antistatic coating, etc.

On the other hand, in the case of a paint used for producing a magnetic recording medium, the adhesive force between the non-magnetic support and the magnetic layer is improved, the magnetic recording medium is prevented from being charged, the film strength is enhanced, and the magnetic layer is thin. It is useful for improving dispersibility and surface smoothness of the lower non-magnetic layer due to layering and surface smoothing. In particular, with the recent trend toward higher recording density in magnetic recording, there is a marked tendency for the recording wavelength to become shorter,
Along with this, there is a further demand for thinner magnetic layers in magnetic recording media. However, when the magnetic layer is made thinner, the influence of the support is likely to appear on the magnetic surface, and deterioration of the electromagnetic conversion characteristics cannot be avoided. For this reason, for example, by providing a non-magnetic undercoat layer on the surface of the non-magnetic support and then providing the magnetic layer as an upper layer, the influence of the surface roughness of the support can be eliminated, and the magnetic layer can be thinned to a high level. A method for achieving output is being used. Therefore, the dendritic or starfish-shaped fine particle titanium dioxide of the present invention can make the surface smoothness of the upper magnetic layer more preferable when it is filled in the non-magnetic layer of the undercoat layer. The filling ratio of the fine particle titanium dioxide into the lower non-magnetic layer is 20 to 80 in terms of volume filling ratio.
%.

When used as a conductive rubber, for example, silicone rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, butadiene-
Acrylonitrile rubber, ethylene-propylene-diethane polymer, ethylene-propylene rubber, fluororubber,
Ethylene-vinyl acetate copolymer, chlorinated polyethylene,
It is mixed with conventionally known ones such as acrylic rubber, chloroprene rubber, urethane rubber, polysulfide rubber, chlorosulfonated polyethylene rubber, and epichlorohydrin rubber.

When it is used as a conductive fiber, it is blended with a fusible fiber such as a polyamide resin, a polyester resin, a polyolefin resin, a polyvinyl resin or a polyether resin.

The conductive composition thus obtained is
Compared with the conventional electrically conductive composition containing a spherical electrically conductive powder, high electrical conductivity can be obtained with a smaller amount of the resin binder, which is economically advantageous. Since such a small amount is required, the binder can be used without lowering its strength. When a high-concentration conductive paint is used, desired conductivity can be obtained even with a thin coating film.

When the dendritic or starfish-like particulate titanium dioxide of the present invention is used as various cosmetics and paints, various organic treatment agents used in the cosmetics field and paint fields, such as carboxylic acids and polyols, It may be coated with at least one organic substance such as amine, siloxane, and silane coupling agent. In that case, dispersibility in cosmetics and paints and durability of coating films may be further improved.

[0024]

【Example】

Example 1 (1) Hydrous titanium oxide obtained by hydrolysis of an aqueous solution of titanium tetrachloride was used as an aqueous suspension having a concentration of 100 g / liter in terms of TiO ₂ . 4 to 2 liters of this aqueous suspension
1400 g of an 8% aqueous sodium hydroxide solution was added with stirring, heated at 95 ° C. for 120 minutes, filtered, and thoroughly washed. The washed cake was repulped with water to obtain an aqueous suspension of 100 g / liter in terms of TiO ₂ , and 1.5 liter of this aqueous suspension was placed in a flask equipped with a reflux condenser, and 570 g of 35% hydrochloric acid was stirred for a moment (4 Mol / sec), followed by heat aging at 95 ° C. for 120 minutes to give a rutile type crystal having a length of 0.30 μm, a thickness of 0.055 μm and a specific surface area of 79.
An aqueous suspension containing m ² / g of dendritic or starfish-like particulate titanium dioxide was obtained.

(2) The aqueous suspension containing the dendritic or starfish-shaped fine particles of titanium dioxide obtained in (1) above is filtered and washed, and the obtained washed cake is dried at 120 ° C. for one day to obtain powder ( Sample A) was obtained.

Comparative Example 1 (1) Hydrous titanium oxide obtained by hydrolysis of an aqueous solution of titanium tetrachloride was used as an aqueous suspension having a concentration of 100 g / liter in terms of TiO ₂ . 4 to 2 liters of this aqueous suspension
1400 g of an 8% aqueous sodium hydroxide solution was added with stirring, heated at 95 ° C. for 120 minutes, filtered, and thoroughly washed. The washed cake is repulped with water to obtain an aqueous suspension of 100 g / liter in terms of TiO ₂ , 1.5 liter of this aqueous suspension is placed in a flask equipped with a reflux condenser, and 570 g of 35% hydrochloric acid is stirred for 30 minutes. 95 after addition
The mixture was heated to 0 ° C. and aged for 90 minutes to obtain an aqueous suspension containing rod-shaped fine particles of titanium dioxide having a long axis of 0.07 μm, an axial ratio of 7, and a specific surface area of 99 m ² / g.

(2) The aqueous suspension containing the rod-shaped fine particles of titanium dioxide obtained in (1) above is filtered and washed, and the obtained washed cake is dried at 120 ° C. for a whole day and night to obtain powder (Sample B). Obtained.

Comparative Example 2 The rod-shaped fine particle titanium dioxide of Sample B of Comparative Example 1 was fired in an electric furnace at 500 ° C. for 1 hour to give a primary particle diameter of 0.06.
Microparticle titanium dioxide (Sample C) having a specific surface area of 25 m ² / g was obtained.

Example 2 An aqueous suspension containing finely divided dendritic or starfish-like titanium dioxide obtained in Example 1 was heated to 90 ° C., into which 150 g of tin chloride (SnCl ₄ .5H ₂ O) and chlorination were added. 25 g of antimony (SbCl ₃ ) was added to 200 ml of 6N hydrochloric acid solution.
And a 10% aqueous sodium hydroxide solution were added in parallel for 60 minutes so as to maintain the pH of the suspension at 2-3, and tin oxide was added to the surface of the dendritic or starfish-like fine titanium dioxide particles. And a hydrate of antimony oxide was applied. The final pH of the suspension at this time was 3. Next, the deposited dendritic or starfish-shaped fine particle titanium dioxide aqueous suspension is filtered, and the specific resistance of the filtrate is 50 μS.
The cake of dendritic or starfish-shaped fine particles of titanium dioxide that has been washed and adhered is dried at 120 ° C. for one day and then calcined in an electric furnace at 500 ° C. for 1 hour to obtain SnO ₂ of 51 as TiO ₂ weight basis. 0.6%, 1 as Sb ₂ O ₃
Dendritic or starfish-shaped fine particles of conductive titanium dioxide powder having a length of 0.36 μm, a thickness of 0.065 μm, and a specific surface area of 33 m ² / g, deposited on a conductive layer of tin oxide containing 3.3% antimony (sample D) was obtained. The powder resistance was measured and found to be 13 Ωcm. The powder resistance is 1 for the sample powder.
A columnar green compact (diameter 18 mm, thickness 3 mm) was formed by molding at a pressure of 00 Kg / cm ² , and its direct current resistance was measured to determine the powder resistance [Ωcm] by the following formula.

[0030]

[Equation 1]

Comparative Example 3 The total amount of the aqueous suspension containing rod-shaped fine particles of titanium dioxide obtained in (1) of Comparative Example 1 was heated to 90 ° C., and then 150 g of tin chloride (SnCl ₄ .5H ₂ O) was added thereto. And 25 g of antimony chloride (SbCl ₃ ) were added to a 6N-hydrochloric acid aqueous solution 200 m.
1 and a 10% aqueous sodium hydroxide solution were added in parallel over 60 minutes so as to maintain the pH of the suspension at 2-3, and tin oxide and antimony oxide were added to the surface of the rod-shaped fine particles of titanium dioxide. Of hydrate was applied.
The final pH of the suspension at this time was 3. Then, the deposited rod-shaped fine particle titanium dioxide aqueous suspension is filtered,
The rod-shaped particulate titanium dioxide cake, which had been washed and deposited until the specific resistance of the filtrate reached 50 μS, was dried at 120 ° C. for one day and then calcined in an electric furnace at 500 ° C. for 1 hour to form TiO 2.
0.1 μm in length, 0.015 μm in thickness, and 41 m in specific surface area deposited by a conductive layer of antimony-containing tin oxide consisting of 47.2% SnO _{2 and} 11.6% Sb ₂ O _{3 based on 2} weight. ² / g of rod-shaped fine particles conductive titanium dioxide powder (Sample E) was obtained. 15Ωcm when powder resistance is measured
Met.

Test Example 1 Samples A and B obtained in Example 1, Comparative Example 1 and Comparative Example 2
Particulate titanium dioxides C and C were used as sunscreen creams in the following formulations. (1) Stearic acid 2.5 parts by weight (2) White beeswax 3.5 〃 (3) Cetanol 3.5 〃 (4) Squalane 17.0 〃 (5) Glycerin monostearate 3.0 〃 (6) Fine particles Titanium dioxide 3.0 〃 (7) Methylparaben 0.1 〃 (8) Glycerin 12.0 〃 (9) Triethanolamine 1.0 〃 (10) Purified water 54.1 〃 (11) Perfume 0.3 〃

The components (1) to (6) heated and mixed at 80 ° C. are added to the components (7) to (10) heated and mixed at 80 ° C., well mixed with a homomixer, and vigorously stirred. . (11) was added at around 45 ° C. to prepare a sunscreen cream.

Evaluation Method Each of the above creams was applied on quartz glass to a film thickness of 25 μm, and the transmitted light of 750 to 300 nm was measured by a spectrophotometer. Table 1 shows the above evaluation results.

[0035]

[Table 1]

Test Example 2 (1) Samples D and E obtained in Example 2 and Comparative Example 3
Each 20 g of acrylic resin (Acridic A-1
65-45; solid content 45% by weight, manufactured by Dainippon Ink and Chemicals, Inc., 30.6 g, toluene / butanol (1/1) mixed solution 16.4 g, and glass beads 50 g were placed in a glass bottle and shaken with a paint shaker for 30 minutes. Finally, it was dispersed to make a mill base.

(2) A paint was prepared by adding the above acrylic resin and toluene / butanol mixed solution so that the pigment concentration was 20%, 30% and 40% to each mill base. This paint was applied to art paper so that the dry film thickness was 37 μm, and naturally dried for 40 hours to prepare a test piece. The electrical resistance of the art paper test piece was measured with a digital ohm meter (R-506 type, manufactured by Kawaguchi Denki Seisakusho), and the surface resistivity was calculated from the following formula. The above results are shown in Table 2.

[0038]

[Equation 2]

[0039]

[Table 2]

[0040]

INDUSTRIAL APPLICABILITY The present invention is a dendritic or starfish-like fine particle titanium dioxide obtained by a simple method of treating an aqueous hydrous titanium oxide suspension with an alkali, then rapidly adding hydrochloric acid and aging by heating. The titanium dioxide is used as a cosmetic or paint having an ultraviolet ray preventing or shielding function by coating or adhering various metal compounds or the like on the particle surface of the titanium dioxide, and as a substrate for a substance imparting a conductive function. It is possible to achieve such a great effect on an industrial scale.

[Brief description of drawings]

FIG. 1 is an electron micrograph (magnification: 100,000 times) showing the particle structure of the dendritic or starfish-shaped fine titanium dioxide powder (Sample A) of the present invention obtained in Example 1.

FIG. 2 is an electron micrograph (magnification: 100,000 times) showing the particle structure of the rod-shaped fine particle titanium dioxide powder (Sample B) obtained in Comparative Example 1.

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Claims (9)

(57) [Claims] 1. A length of 0.2 to 0.5 μm, a thickness of 0.05 to 0.1 μm, and a specific surface area of 70.
Dendritic or starfish-like particulate titanium dioxide, which is ˜130 m ² / g. 2. The dendritic or starfish-like fine particle dioxide according to claim 1, which has a coating of at least one hydrous oxide or oxide selected from the group consisting of aluminum, silicon, titanium, zirconium, tin and antimony on the surface of the particles. Titanium. 3. The dendritic or starfish-shaped fine particle conductive titanium dioxide according to claim 1, which has a conductive layer made of antimony-containing tin oxide or tin-containing indium oxide on the surface of the particles. 4. Titanium oxide hydroxide is treated with alkali, and then the obtained reaction product and hydrochloric acid are mixed instantaneously at a ratio of 1 to 4 mol of hydrochloric acid to 1 mol of titanium oxide of the reaction product. And then heat aging at 85 ° C. or higher, the length is 0.2 to 0.5 μm, the thickness is 0.05 to 0.1 μm, and the specific surface area is 70.
A method for producing dendritic or starfish-shaped fine particle titanium dioxide having a particle size of ˜130 m ² / g. 5. A dendritic or starfish-shaped fine particle titanium dioxide obtained by the method of claim 4 is used as a slurry, and at least one selected from the group consisting of water-soluble salts of aluminum, silicon, titanium, zirconium, tin and antimony. A method for producing dendritic or starfish-shaped fine particle titanium dioxide, characterized in that the particle surface of the fine particle titanium dioxide is coated with a hydrous oxide or oxide of the element by adding. 6. A conductive composition containing the dendritic or starfish-shaped fine particles of titanium dioxide according to claim 3. 7. A sunscreen cosmetic containing the dendritic or starfish particulate titanium dioxide of claim 1 or 2. 8. An anti-UV coating material containing the dendritic or starfish particulate titanium dioxide of claim 1 or 2. 9. An ultraviolet protection plastics composition containing the dendritic or starfish-shaped fine particles of titanium dioxide according to claim 1 or 2.