JP2728271B2 - Method for producing spherical oxide particles - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing spherical metal oxide particles having a uniform particle size.

Technical background of the invention and its problems A method for producing silica particles of 0.05 to 2 μm by contacting an alkyl silicate with ammonia and water in an alcohol solvent is disclosed by W. Stber et al. [J. col.
loid & Interface Sci, 26 , (1968)].

Further, a method is also known in which a solution obtained by dissolving a metal alkoxide in an organic solvent and a solution comprising water and a dispersant are mixed, and the metal alkoxide is hydrolyzed to produce fine ceramic powder (particularly known). See JP-A-60-166203). In addition, it has been reported that the progress of silica sphere growth with respect to reaction conditions in the case of using a mixed solution comprising ethanol, aqueous ammonia and ethyl silicate was observed based on the particle size distribution ("Powder and powder metallurgy"). 23, 4
Pp. 137-142).

However, conventional alcoholic solvents such as those described above
In the method for producing silica particles in an alkyl silicate / ammonia / water-based solution, there is a problem that control of particle growth and control of particle size distribution are not easy, and secondary aggregation of particles is also likely to occur.
Such a method is not suitable as a method for industrially producing silica particles having a uniform particle diameter.

JP-A-60-166203 discloses a method in which a dispersant is used to suppress aggregation of particles generated by hydrolysis. The method described in this publication is a method very suitable for synthesizing extremely fine silica particles, but is unsuitable for synthesizing oxide particles having a relatively large particle size and uniform particle size. It is.

Furthermore, in these conventionally known methods for producing oxide particles by one step, it takes a long time to obtain oxide particles having a desired particle size, particularly relatively large particles, and lacks uniformity in particle size. There was a problem.

Object of the Invention The present invention is intended to solve the problems associated with the prior art as described above, and efficiently produces high-purity spherical oxide particles having a small particle agglomeration and a uniform particle size. It is intended to provide a way to do so.

SUMMARY OF THE INVENTION The method for producing spherical oxide particles according to the present invention comprises, in a dispersion in which core particles are dispersed, hydrolyzing a metal alkoxide in the presence of a protective colloid, and converting the hydrolysis product into the core particles. It is characterized by deposition and particle growth.

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for producing metal oxide particles by hydrolyzing metal alkoxides, wherein the hydrolysis reaction of metal alkoxides is carried out in the presence of a protective colloid in a dispersion in which core particles are dispersed. This is a method for producing a spherical oxide in which a hydrolysis product of a metal alkoxide is deposited on core particles to grow the particles.

In the method of the present invention, the metal alkoxide is hydrolyzed in an alcohol solvent in which core particles are dispersed.

The alcohol solvent used for hydrolyzing the metal alkoxide usually contains alcohol, water and ammonia.

The amount of the alcohol solvent used at the time of hydrolysis of the metal alkoxide in the present invention, based on the metal alkoxide,
Usually, the weight ratio is 1 to 50 times, preferably 2 to 20 times.

The amount of water added to hydrolyze the metal alkoxide is usually at least 4 times the molar ratio to the metal alkoxide, but in particular, in the present invention, the molar ratio is 5 to 100.
Preferably, it is about twice.

Ammonia is the pH of the alcohol solvent during hydrolysis.
It is added in such an amount that the value can be kept in the range of 10-13.

The temperature during the hydrolysis performed as described above is
Usually it is 10-100 ° C.

The metal alkoxide used in the present invention can be represented by M (OR) _n . In the above formula, n is a metal M
Where M is Be, Al, P, Si, Sc, Ti, V, Cr, Fe, Ni,
Zn, Ga, Ge, As, Se, Y, Zr, Nb, In, Sn, Sb, Te, Hf, Ta, W, Pb, B, V
Represents any atom of O, Bi, Ce and Cu. Also. R is an alkyl group, usually having 1 to 5 carbon atoms.
, Preferably an alkyl group having 2 to 3 carbon atoms.

The alcohol solvent used in the production method of the present invention can be appropriately selected from alcohols that dissolve the metal alkoxide, and is generally used when the number of carbon atoms of the alkyl group constituting the alcohol is large. The distribution tends to be broad, and therefore, in the present invention, alkyl alcohols having 1 to 6 carbon atoms are preferably used. Among these alcohols, particularly preferred alcohols are methanol, ethanol, and propanol having 1 to 3 carbon atoms. is there.

The present invention hydrolyzes a metal alkoxide in an alcohol solution of a metal alkoxide as described above in the presence of a protective colloid.

As the protective colloid used in the present invention, among the substances capable of uniformly dispersing the core particles and the obtained spherical oxide particles in a liquid and further preventing aggregation of the core particles and the obtained spherical oxide particles. Can be selected as appropriate. Examples of such substances include gelatin,
Examples include casein soda, globulin, hemoglobin, albumin, gum arabic, starch, dextrin, protalbic acid, sodium alginate, risarbic acid, and polyvinyl alcohol. The substances forming such protective colloids can be used alone or in combination.

The protective colloid as described above is preferably used such that 0.05 ≦ (protective colloid / particle) × 100 ≦ 13% by weight based on the obtained spherical oxide particles. The amount of protective colloid
If the amount is less than 0.05% by weight, it may not be possible to effectively prevent the aggregation of the particles, while if it exceeds 13% by weight, the particles are likely to aggregate. The protective colloid can be added in advance to the dispersion of the core particles, or can be added together with the metal alkoxide when adding the metal alkoxide.

Examples of the core particles used in the present invention include metal oxide particles, metal hydroxide particles, and resin particles. These core particles can be used alone or in combination. When the core particles are metal oxide particles or metal hydroxide particles, the metal alkoxide to be added may be a metal alkoxide having the same kind of metal element as the core particles, or a metal alkoxide having a different element. It doesn't matter. The particle size of the core particles used in the present invention is preferably in the range of 0.05 to 9.0 μm, and more preferably particles having a uniform particle size distribution are used.

In the present invention, as the core particles, the metal alkoxide is hydrolyzed in the alcohol solvent as described above.
Particles produced by a general method for obtaining particles of 0.2 to 0.3 μm can also be used. The core particles obtained by this method do not need to be newly dispersed in a liquid because the core particles are already well dispersed in the alcohol solvent at the production stage, and can be used very preferably in the present invention. . Further, spherical oxide particles produced by the method of the present invention can be used as core particles.

The standard deviation (SD) of the spherical oxide particles thus obtained is usually in the range of 0.01 to 0.20 μm. Further, the uniformity coefficient (CV) calculated by the equation described below is usually
It is in the range of 1.0 to 2.0.

Further, the spherical oxide particles obtained by the production method according to the present invention have an agglomeration ratio of 4.0% or less, and have a characteristic that they are extremely difficult to agglomerate.

Effect of the Invention According to the method for producing spherical particles according to the present invention, spherical oxide particles, in the presence of a protective colloid in a dispersion in which core particles are dispersed, hydrolyze a metal alkoxide, and the hydrolysis product Is deposited on the core particles to grow the particles, so that high-purity spherical oxide particles having a uniform particle size and less aggregation of the resulting spherical particles can be efficiently produced.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 After mixing 5.5 g of water and 78 g of 28% ammonia water in 351 g of ethanol, the mixture was kept at 15 ° C. while stirring, and then 14.5 g of 28% ethyl silicate was diluted with 351 g of ethanol. The liquid was added to the mixture. Stirring was further continued for 2 hours to obtain a core particle dispersion I in which core particles having an average particle size of 0.35 μm were dispersed.

Under stirring, 457 g of ethanol, 706 g of water and 28 g of water were added to 457 g of the nuclear particle dispersion I having a liquid temperature of 35 ° C. and a pH of 12.5.
A mixture of 579 g of aqueous ammonia solution and 0.3 g of gelatin and a liquid obtained by diluting 1537 g of 28% ethyl silicate with 362 g of ethanol were simultaneously applied for 19 hours, and the pH value of the liquid during the reaction was raised to 1
A hydrolysis reaction was carried out by gradually adding while maintaining at 1.8, to obtain a liquid in which spherical oxide particles in which the hydrolyzate was deposited and grown on the core particles were dispersed.

Example 2 Liquid 2499 in which the spherical oxide particles obtained in Example 1 were dispersed
After adding and mixing 2696 g of ethanol, 20 g of water, and 538 g of 28% aqueous ammonia to g, the liquid temperature was maintained at 35 ° C. and the pH value was maintained at 12.4 with stirring to obtain a nuclear particle dispersion liquid II.

191 g of ethanol, 501 g of water and 28
A mixture of 305 g of aqueous ammonia and 6.8 g of gelatin and a solution of 810 g of 28% ethyl silicate diluted with 191 g of ethanol were simultaneously added over 15 hours, and gradually added while maintaining the pH value of the solution during the reaction at 12.0. A hydrolysis reaction was carried out to obtain a liquid in which the hydrolyzate was deposited on the core particles and the spherical oxide particles that grew were dispersed.

Example 3 A liquid in which the spherical oxide particles obtained in Example 2 were dispersed was centrifuged, the supernatant was discarded, and water was added to the remaining precipitate to make a total amount of 1527 g, followed by sufficient stirring. Take 832 g of this solution, add 3697 g of ethanol, 784 g of water, and 924 g of 28% aqueous ammonia and mix them.
° C, and the pH value of the liquid is maintained at 12.4, and the nuclear particle dispersion liquid III is maintained.
I got

To this core particle dispersion III, 151 g of ethanol, 751 g of water and 2
A mixture of 962 g of 8% aqueous ammonia and 5.0 g of gelatin and a solution obtained by diluting 641 g of 28% ethyl silicate with 151 g of ethanol were simultaneously added for 15 hours, and gradually added while maintaining the pH value of the reaction solution at 11.9. A hydrolysis reaction was performed to obtain a liquid in which the hydrolyzate was deposited on the core particles and the spherical oxide particles that grew were dispersed.

Example 4 The liquid in which the spherical oxide particles obtained in Example 3 were dispersed was centrifuged, and the supernatant was discarded. Water was added to the remaining precipitate to make the total amount to 1430 g, followed by sufficient stirring. Take 874g from this liquid,
3884 g of ethanol, 824 g of water and 971 of 28% ammonia water
g, and then, while stirring, the liquid temperature was kept at 65 ° C., and the pH value of the liquid was kept at 12.3 to obtain a nuclear particle dispersion liquid IV.

124 g of ethanol, 888 g of water and 28
A mixture of 789 g of aqueous ammonia 789 g and gelatin 16.3 g, and a liquid obtained by diluting 526 g of 28% ethyl silicate with 124 g of ethanol were simultaneously added for 13 hours, and gradually added while maintaining the pH value of the reaction solution at 11.7. A liquid in which oxide particles were dispersed was obtained.

Example 5 The liquid in which the spherical oxide particles obtained in Example 4 were dispersed was centrifuged, the supernatant was discarded, and water was added to the remaining precipitate to make a total amount of 1363 g, followed by sufficient stirring. Take 896g from this liquid,
To this, 3983 g of ethanol, 845 g of water, and 995 of 28% ammonia water
After mixing, the liquid temperature was maintained at 65 ° C. and the pH value of the liquid was maintained at 12.5 with stirring to obtain a nuclear particle dispersion liquid V.

110 g of ethanol, 1174 g of water, 2
A mixture of 699 g of 8% aqueous ammonia and 26.1 g of gelatin and a solution obtained by diluting 466 g of 28% ethyl silicate with 110 g of ethanol were simultaneously added for 12 hours, and gradually added while maintaining the pH value at 11.5 during the reaction. A decomposition reaction was performed to obtain a liquid in which spherical oxide particles that grew by depositing a hydrolyzate on the core particles were dispersed.

Example 6 362 g of ethanol and 706 g of water added to the core particle dispersion I
Except that the mixture of 579 g of 28% aqueous ammonia and 0.3 g of gelatin was replaced with a mixture of 362 g of ethanol, 706 g of water, 579 g of 28% aqueous ammonia and 0.43 g of polyvinyl alcohol,
A liquid in which spherical oxide particles were dispersed was obtained in the same manner as in Example 1.

Example 7 191 g of ethanol and 501 g of water added to the nuclear particle dispersion liquid II
Spherical oxidation was performed in the same manner as in Example 2 except that the mixture of 305 g of 28% aqueous ammonia and 6.8 g of gelatin was replaced with a mixture of 191 g of ethanol, 519 g of water, 305 g of 28% aqueous ammonia, and 6.8 g of polyvinyl alcohol. A liquid in which the material particles were dispersed was obtained.

Example 8 151 g of ethanol and 751 g of water added to the core particle dispersion liquid III
And a mixture of 962 g of 28% aqueous ammonia and 5.0 g of gelatin,
Except that a mixture of 151 g of ethanol, 764 g of water, 962 g of 28% ammonia water and 5.0 g of polyvinyl alcohol was used.
In the same manner as in Example 3, a liquid in which spherical oxide particles were dispersed was obtained.

Comparative Example 1 362 g of ethanol and 706 g of water added to the core particle dispersion I
Spherical oxide particles were dispersed in the same manner as in Example 1 except that the mixture of 579 g of 28% aqueous ammonia and 0.3 g of gelatin was replaced with a mixture of 362 g of ethanol, 706 g of water, and 579 g of 28% aqueous ammonia. A liquid was obtained.

The following evaluations were performed on the spherical oxide particles obtained in Examples and Comparative Examples.

(1) Average particle size (Dp, μm): Measured by a scanning electron microscope photomicrograph.

(2) Standard deviation (SD, μm): Calculated in the same manner as 1.

(3) Uniformity coefficient (Cv): Cv was determined by the following equation.

Cv = (SD / Dp) × 100 (4) Aggregation ratio: For 400 spherical oxide particles in a scanning electron microscope photo, the percentage of the total number of aggregated spherical oxide particles of 400 is referred to as the aggregation ratio. And

 Table 1 shows the results.

Claims (1)

(57) [Claims] The present invention is characterized in that a metal alkoxide is hydrolyzed in a dispersion in which core particles are dispersed in the presence of a protective colloid, and the hydrolysis product is deposited on the core particles to grow the core particles. A method for producing spherical oxide particles.