JPS61168528A - Truly spherical fine particle composed of titanium oxide - Google Patents

Abstract

PURPOSE:To improve the fluidity and dispersibility of titanium oxide fine particle, by specifying the average particle diameter, particle size distribution, sphericity, and surface area of the particles. CONSTITUTION:The objective truly spherical fine titanium oxide particle has an average particle diameter of 1-20mu, a particle size distribution of 0.5-30mu, a sphericity of 0.85-1.00 and a surface area of 1-50m<2>/g. The titanium oxide powder can be produced from a colloidal liquid of titanium oxide or hydrated oxide or from a mixture obtained by adding titanium oxide gel to the above colloidal liquid, by spray-drying the colloidal liquid to form a sphere by the surface tension of the colloidal liquid, and sintering the particle to decrease its surface area.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fine titanium oxide powder that is perfectly spherical, has a sharp particle size distribution, and has an average particle size of 1 to 20μ. Particle size is 1~
20μ, particle size distribution of 0.5 to 30μ, sphericity of 0.85 to 1.00, and surface area of 1 to 50rrF/g.

There are two types of titanium oxide powders that are conventionally known industrial products. One is a normal titanium pigment obtained by hydrolyzing a titanium metal salt and/or titanate, and the other is a titanium powder obtained by vapor phase oxidation of titanium tetrachloride or the like. The former titanium oxide powder is
Usually, a hydrous titanium oxide gel is created by hydrolyzing titanium sulfate or hydrochloride in an aqueous solution, and then washed, dried, and calcined to form a gel with a desired crystal structure.
A lump of titanium oxide with a size of 111 mm was prepared and then finely ground to an average particle size of 0.2 to 03 μm. This powder has an amorphous shape, and since it has very strong adhesiveness, agglomeration occurs to form loose secondary agglomerated particles ranging in size from several micrometers to over 100 micrometers, and their shape is also irregular. Therefore, when this powder is used, for example, in paints or cosmetics, it has drawbacks such as poor dispersibility, poor spreadability and fluidity, and cannot be used in large quantities.

On the other hand, the latter titanium oxide powder is made by vaporizing a volatile titanium compound and burning it in the same size as the vaporized state to form fine particles, so the shape of the missing particles is almost spherical and the average particle size is It is very small, about 0.03μ. Furthermore, since these primary particles are produced by high-temperature combustion, the surface activity of the particles is reduced and their cohesive force is weak. However, since the secondary particles are too small, they not only loosely aggregate to form secondary aggregated particles, but also loosely aggregate to form tertiary aggregated particles. However, since the cohesive force between the particles is weak, they become very bulky, causing problems in transportation and handling.

However, when used, it has good dispersibility, so it returns to -order particles, and since the size of these -order waves is about 11/10 of visible light, it is transparent and has no hiding power, so it is used as a white pigment. Can not. Furthermore, the crystal structure of this titanium oxide powder is difficult to control during the manufacturing process, and it is a mixture of anatase and rutile.

In contrast to the conventional titanium oxide powder described above, the true spherical fine powder made of titanium oxide of the present invention.

Sphericity 0.85-1.00, average particle diameter 1-20μ1, particle size distribution 0.5-30μ, and surface area 1-50m2/g
It is characterized by

The sphericity referred to here refers to the fact that single particles are dispersed so that they do not overlap, and an electron micrograph is taken at a magnification of 2000 times using a scanning electron microscope (SEM), and this image is analyzed using a Shimadzu image analyzer. HD is the equivalent diameter obtained by measuring the area and circumference of the projected plane of one single particle and assuming that it is a perfect circle from one area, and the braiding diameter that is obtained from the circumference and assuming that it is a perfect circle. was defined as Hd, and the ratio of these two was defined as sphericity.

A ball with this value of 0.850 to 1.00 was defined as a true sphere. Among the sampled particles, those in which 90% or more of the particles were true spheres were named true spherical fine particles. Incidentally, particles with small adhesion or depression on the surface are not considered to be true spheres.

The titanium oxide powder of the present invention can be produced using a colloidal solution of a titanium oxide and/or hydrous oxide or a mixed solution obtained by adding a titanium oxide gel thereto as a starting material.

The colloidal liquid of titanium oxide and/or hydrous oxide is
Generally, metatitanic acid obtained by hydrolyzing one or more of titanium mineral acid salts, organic acid salts, and titanate salts is neutralized with aqueous ammonia, washed well with pure water, and then treated with hydrochloric acid. In addition, it can be obtained by lowering the pH to 2 or less. However, the method for producing the colloidal liquid is not limited to the above-mentioned method, and may be produced by any method. However, the average particle size of the colloid needs to be 2500 Å or less, preferably 800 Å or less. Average particle size is 2
This is because if it is 500 Å or more, the interparticle strength during drying will be weak and breakage will occur during drying, resulting in not only a wide particle size distribution but also a concern that non-spherical particles may be mixed in.

The titanium oxide gel that is mixed into the colloidal liquid as necessary may be either a hydrogel and/or a xerogel. For example, any material such as titanium Aerosil obtained by a gas phase oxidation method or ordinary pigmented titanium oxide can be used. However, the average particle diameter of the gel needs to be 11z or less, and preferably 0.5μ or less. Further, it is preferable that the mixed state be as uniform as possible. Further, the viscosity at this time must be 500 cp or less, more preferably 50 cp or less.

The colloidal liquid or gel-containing colloidal liquid thus obtained is dried by a spray drying method. At this time, the colloidal liquid is granulated into spherical particles due to the surface tension of the liquid. The fine particles granulated in this way do not have enough strength when dried alone, and may not be able to maintain their shape due to mechanical force when dispersed in cosmetics or paints. By firing the primary particles that make up the fine particles and the secondary
It is possible to promote sintering between secondary particles and increase mechanical strength. This sintering inevitably increases the surface area of the particles to 50
m2/g or less. By the way, powder with a surface area of 50m2/g or more.

For example, when used in cosmetics, due to its strong surface activity,
Oxidation, reduction, or decomposition of organic substances such as fragrances may occur, leading to deterioration of their quality.

The true spherical fine particles of titanium oxide according to the present invention have a very large average particle diameter and a true spherical shape compared to ordinary titanium oxide powder, so they have very good fluidity when handling the powder, and they also have excellent fluidity when handling the powder. Since it has no properties, it has extremely good dispersibility when mixed with other substances. In addition, the hiding power, which is particularly important as a white pigment, is the same as that of ordinary white pigments, and the adhesion is not strong, so when used as a cosmetic, it does not lose its hiding power, spreads well, and has a high level of compaction. In the case of molded products, makeup cosmetics with good contents can be obtained without causing caking even after use over time. In addition, when this product is used in UV-blocking cosmetics, it has no agglomeration and is perfectly spherical, so it spreads well on the skin, making it possible to create transparent UV-blocking cosmetics without the need for thick makeup. can.

In addition, if the surface of these titanium oxide fine particles is made hydrophobic with a titanium coupling agent, etc., and this is highly dispersed in a transparent resin paint, it can be applied to the surface of glass such as a show window to create a thin film, resulting in transparent UV-cut glass. It is very effective as it eliminates the discoloration of products in the show window due to ultraviolet rays. Furthermore, since this titanium oxide acts as a filler for the resin, it also serves as a hard coating agent for the ultraviolet resin film. Furthermore, if a UV-cutting film is made using a similar method and used in agricultural greenhouses, it will have the effect of speeding up the growth of certain plants. Furthermore, the average particle size is 1 to 2.
If 0μ true spherical titanium oxide is used for letterpress printing paper,
It has various beneficial effects such as improving ink adhesion and eliminating ink smearing.

Example 1 Titanium sulfate containing 14.2 wt% of titanium as an oxide was hydrolyzed with aqueous ammonia, and after washing thoroughly with pure water, hydrochloric acid was added to adjust the pH to 2 or less.

T10. A titania sol with a concentration of 31% and 7wt% was obtained. This sol was supplied to the i-type two-fluid nozzle, and the drying atmosphere temperature was 70°C while adjusting the processing liquid amount to 60Q/Hr, the air/liquid ratio = 2100, and the air flow rate = Matsuha 1.1.
The air volume was adjusted so that the humidity was 6.6 vol. 1%. The obtained dry powder was calcined at 600° C. for 3 hours and then measured using a particle size distribution analyzer Capa-500 manufactured by Itaba. This was also measured using a JEOL JSM-T20 scanning electron microscope (
A photograph was taken using a SEM), and the image was analyzed using an image analyzer manufactured by Shimadzu, and the sphericity was determined from the projection surface of each single particle. Moreover, the surface area was measured by the BET method. The results are shown in Table-1. An electron micrograph of this powder is shown in FIG. 16. Example 2 Titanium oxide powder was obtained in the same manner as in Example 1 except that the air/liquid ratio was changed to 3500. An electron micrograph of this powder is shown in FIG.

Example-3 Titanium oxide powder was obtained in the same manner as in Example-1 except that the firing temperature was changed to 800°C. An electron micrograph of this powder is shown in FIG.

Example-4 In place of the titania sol used in Example-1.

This titanium silua (0 parts) and titanium dioxide Aerosil (
Titanium oxide powder was obtained in the same manner as in Example 1, except that 30 parts of Nippon Aerosil P-25) was used. An electron micrograph of this powder is shown in FIG.

Table 1 summarizes the properties of titanium oxide powder obtained in each example.
Shown below.

Table-1

[Brief explanation of the drawing]

1 to 4 are electron micrographs of titanium oxide powders obtained in Examples 1 to 4, respectively. Patent applicant Catalysts & Chemicals Co., Ltd. 1 Figure-C-), k Figure 3 Umbrella]; 4th ring

Claims (1)

[Claims] 1. The fine particles have an average particle diameter of 1 to 20 μ, a particle size distribution of 0.5 to 30 μ, a sphericity of 0.85 to 1.00, and a surface area of 1 to 50 m^2/g. True spherical fine particle powder made of titanium oxide.