JPH06122516A - Production of inorganic oxide particle - Google Patents

Abstract

PURPOSE:To produce inorganic oxide particles having controlled particle diameter by hydrolyzing an organometallic compound while controlling the electrical conductivity of a reaction liquid composed of a hydrolysis catalyst, water, an electrolyte and a solvent at the start of the reaction. CONSTITUTION:A solvent such as methanol is incorporated with a hydrolysis catalyst such as ammonia water in an amount to get a water-content of 0.1-30wt.% and a catalyst content of 1-10wt.% based on the hydrolyzing object. An electrolyte substance such as NaOH is added to the obtained mixture at a liquid temperature of 0-60 deg.C to adjust the electrical conductivity to 0-10ms/cm at the start of the reaction. A methanol solution of a hydrolyzable organometallic compound expressed by the formula M(OR)m or MRn(OR)k-n [(m) is 1-4; (k) is 1-4; n<k; R is alkyl; M is metallic element such as Na, K, Ca, Al, Ti or Zr] is dropped to the above product to synthesize inorganic oxide particles such as SiO2 particles. The particles are separated by filtration, washed and dried to obtain inorganic oxide particles having particle diameter of 0.1-10mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing inorganic oxide particles, and more particularly to a method for controlling particle diameter in producing inorganic oxide particles.

[0002]

2. Description of the Related Art The following method has been known as a method for controlling the diameter of inorganic oxide particles such as silica particles.

For example, a method of controlling the particle size by previously synthesizing silica seed particles and growing the silica seed particles (Japanese Patent Laid-Open No. 63-112411), or controlling the particle size by keeping water and ammonia concentrations constant. The method (Japanese Patent Laid-Open No. 63-310714) and the like are known. However, these methods have a problem that the manufacturing process is complicated and the reproducibility is poor at the same time.

On the other hand, a method of controlling the particle size by changing the concentration of hydrochloric acid used in the hydrolysis reaction and the reaction temperature (Japanese Patent Laid-Open No. 159911) is also known. However, in this method, the reaction time is long, and when the reaction is attempted to be completed in a short time, the silica particles aggregate to form a lump, and it is not possible to obtain uniform monodisperse silica particles.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing inorganic oxide particles having an arbitrary particle size in a controlled and stable manner.

[0006]

[Means for Solving the Problems] The inventors of the present invention have conducted earnest research on a method for solving the problems of the above-mentioned conventional techniques and for producing inorganic oxide particles having an arbitrary particle size in a controlled and stable manner. I came. As a result, they have found that the particle size can be controlled by controlling the electric conductivity of the hydrolysis reaction liquid at the start of the reaction, and have completed the present invention.

That is, the present invention provides a method for producing inorganic oxide particles by hydrolyzing a hydrolyzable organometallic compound in a reaction solution comprising a hydrolysis catalyst, water, an electrolyte substance and a solvent. Is a method for producing inorganic oxide particles, which is characterized by controlling the particle size by controlling the electrical conductivity at the start of the reaction, and another invention is ammonia,
When the alkoxysilane is hydrolyzed in a reaction liquid consisting of water, an electrolyte substance, and alcohol to produce silica particles, the electric conductivity at the start of the reaction of the reaction liquid (hereinafter, referred to as start-up conductivity) is controlled. This is a method for producing silica particles, which is characterized by controlling the particle size.

The method for producing the inorganic oxide particles of the present invention, which can control the diameter of the inorganic oxide particles, will be specifically described below.

The production of the inorganic oxide particles of the present invention is carried out with a solvent,
It is carried out by hydrolyzing an organometallic compound (hereinafter, also referred to as an organometallic compound) which can be hydrolyzed in a reaction liquid composed of a hydrolysis catalyst, water and an electrolyte substance.

Usually, the particle size of the inorganic oxide particles is controlled by a method of changing the amount of the organometallic compound used in the reaction, but in the method of the present invention, the particle size can be controlled by the conductivity at the start of the reaction solution. In other words, the particle size can be easily controlled without changing the reaction time.

In the present invention, the particle size means a value obtained by observing the inorganic oxide particles with a scanning electron microscope, measuring the diameter of the particles in the longitudinal direction, and calculating the average diameter.

The electric conductivity of the present invention is defined by the reciprocal of the electric resistance of the reaction solution, and is represented by the unit S / cm (= 1 / ohm). The electrical resistance of a solution cannot be generally stated because the rate of change in electrical resistance varies depending on the dissolved chemical species, but it varies depending on the amount of dissolved ions. The electrical conductivity is
It also changes depending on the ion concentration in the reaction solution, the composition of the reaction solution, and the temperature of the reaction solution.

Any method may be used to measure the electric conductivity, but the electric conductivity may be measured by a commercially available electric conductivity meter (for example, CM-11P manufactured by Toa Denpa Kogyo Co., Ltd.) which is composed of a platinum electrode, a Hoystone bridge, and the like. Good.

The starting conductivity in the present invention means a solvent,
It refers to the electric conductivity of a reaction liquid when a reaction liquid composed of a hydrolysis catalyst, water, and an electrolyte substance is prepared and the reaction temperature is appropriately selected.

The control of the conductivity at the start may be performed by using any component in the reaction solution, but since the electrolyte substance which can greatly change the electric conductivity in a small amount does not greatly deteriorate the composition of the reaction solution. Preferably used. That is, a method of keeping a mixed solution of a solvent, a hydrolysis catalyst, and water at a reaction temperature in advance and adding an electrolyte substance until the target electric conductivity is reached while measuring the electric conductivity is suitable and simple.

The inorganic oxide particle size is determined by the conductivity at the start of the reaction solution, but it may be changed depending on the reaction conditions used, the reaction volume, the addition rate of the organometallic compound, and other synthesis conditions, and therefore it is used. It is preferable to previously obtain a calibration curve of the conductivity at the start and the particle size of the inorganic oxide under a predetermined synthesis condition. By using this calibration curve, the particle size of the inorganic oxide particles can be controlled to a desired particle size more accurately and with high reproducibility by the starting conductivity of the reaction solution.

The solvent used in the present invention is not particularly limited as long as it can dissolve the organometallic compound as the reaction raw material and can be mixed uniformly with water at a constant ratio, but is generally easily available. Possible alcohols such as methanol, ethanol, iso-propanol and ethylene glycol are preferably used. Further, two or more kinds of solvents may be mixed and used.

In the present invention, a hydrolysis catalyst and water are used. Each of these may be used alone, or a solution prepared by previously mixing both may be used. The content of water in the reaction solution varies depending on the type of organic metal compound and solvent used and cannot be unconditionally limited, but it is generally preferable to select from the range of 0.1 to 30% by weight. The content of the hydrolysis catalyst also varies depending on the type of organic metal compound and solvent used, etc., and cannot be unconditionally limited,
It is preferably in the range of 1 to 10% by weight. When the concentrations of water and the hydrolysis catalyst in the reaction solution are lower than the respective ranges described above, the growth of the particle size is delayed and the inorganic oxide particles having a uniform particle size cannot be obtained. On the other hand, when it is higher than the above range, the growth of the particle size is accelerated, but the inorganic oxide particles having a uniform particle size cannot be obtained.

As the above hydrolysis catalyst, a known base or acid hydrolysis catalyst can be used, and it may be determined according to the kind of the intended inorganic oxide particles.

When the inorganic oxide particles are silica, zirconia, titania, or a composite oxide thereof, ammonia; amines such as propylamine and aniline; base hydrolysis of amides such as dimethylformamide and acetamide. A catalyst is used. If the inorganic oxide particles are alumina or composite oxide particles containing alumina and a gel is formed without particles when a base hydrolysis catalyst is used, a mineral acid such as sulfuric acid or hydrochloric acid is used. Alternatively, an acid hydrolysis catalyst such as an organic acid such as acetic acid or citric acid is used.

Next, as the electrolyte substance used in the present invention,
The above-mentioned solvent, which is soluble in a reaction liquid containing water, and is a substance which does not react with the solvent, the hydrolysis catalyst, and water,
Furthermore, there is no particular limitation as long as it is a substance that ionically dissociates in this reaction solution. Representative substances include inorganic salts such as sodium hydroxide, calcium hydroxide, sodium chloride, ammonium chloride and sodium nitrate, organic salts such as sodium glutamate and sodium aspartate, and the like. Two or more kinds of the electrolyte substances may be mixed and used.

The content of the electrolyte substance is determined by the value of electric conductivity to be set, the kind of the organometallic compound and the solvent, and the like. Generally, the reaction solution is used so that the electric conductivity at the start of the reaction is 0 to 10 mS / cm. When the electric conductivity of the reaction solution at the start of the reaction is higher than the above range, aggregation of particles is likely to occur, and thus it tends to be difficult to obtain inorganic oxide particles having a uniform particle size.

The hydrolyzable organometallic compound used in the present invention is typically represented by the general formula M (OR) m [m = 1 to 4] MRn (OR) k−n [k = 1 to 4]. , An integer smaller than n = k], or a low condensate obtained by partially hydrolyzing these metal alkoxides. In the above general formula, M is Na, K, Ca,
A metal element such as Al, Si, Ti, and Zr is shown, and R is an alkyl group such as an ethyl group and a butyl group.

Specific examples of the hydrolyzable organometallic compound include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane and phenyltriethoxysilane; sodium methoxide. , Sodium alkoxides such as sodium ethoxide; aluminum alkoxides such as trinormalbutoxyaluminum and triisopropoxyaluminum; titanium titanium alkoxides such as tetraisopropoxytitanium and tetranormalbutoxytitanium; zirconium such as tetraisopropoxyzirconium and tetranormalbutoxyzirconium. Examples include alkoxides.

These organometallic compounds may be used alone or
A mixture of two or more species may be used, and in the latter case, a composite inorganic oxide is produced.

As mentioned above, since the particle size also changes depending on other reaction conditions such as the reaction amount of the organometallic compound, when the present invention is carried out, it is necessary to keep the conditions other than the starting conductivity constant. is there.

The hydrolysis reaction conditions of the present invention are not particularly limited, but generally, the reaction is carried out at 0 to 60 ° C. under atmospheric pressure.

[0028]

INDUSTRIAL APPLICABILITY When the inorganic oxide particles of the present invention are produced, the electric conductivity of the reaction solution at the start of the reaction is controlled, so that the inorganic oxide particles having an arbitrary particle diameter in the range of 0.1 to 10 μm can be obtained. The particles can be produced stably with good reproducibility.

[0029]

EXAMPLES The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

Example 1 1600 m of methanol in a glass flask equipped with a stirrer
1, 356 ml of ammonia water (25% by weight) were added, and the reaction solution temperature was kept at 10 ° C. Sodium hydroxide (5 mol /
l) Add little by little to make the electric conductivity of the reaction liquid 2.15 S / c.
It matched to m. 25 ml / h of 163 ml of a methanol solution (22% by weight) of tetraethoxysilane (trade name: ethyl silicate 28, manufactured by Colcoat Chemical Co., Ltd.) was added to this reaction liquid.
The silica particles were synthesized by adding dropwise at a rate of. The silica particles were recovered from the reaction solution by centrifugation or spontaneous precipitation, and washed by centrifugation or decantation with a large amount of solvent.

The particle size of the obtained silica particles was 1.50 μm as a result of observation with a scanning electron microscope. This reaction was repeated 3 times to confirm the reproducibility of synthesis. The results are shown in Table 1.

[0032]

[Table 1]

Comparative Example 1 Comparative Example 1 shows the result of synthesizing silica particles in Example 1 when the control of the electric conductivity at the start of the reaction of the reaction solution was not performed. The same procedure as in Example 1 was performed except that the amount of the electrolyte substance added was 67 mmol. The results are shown in Table 2.

[0034]

[Table 2]

Examples 2 to 4 The same procedure as in Example 1 was carried out except that the amount of sodium hydroxide added was changed to the starting conductivity shown in Table 3. The results are also shown in Table 3. From this, it can be seen that there is a substantially linear relationship between the starting conductivity and the particle size.

[0036]

[Table 3]

Examples 5 to 9 The same procedure as in Example 1 was carried out except that the electrolyte substances shown in Table 4 were used instead of sodium hydroxide. The results are also shown in Table 4.

[0038]

[Table 4]

Examples 10 to 13 The same procedure as in Example 1 was carried out except that triethoxyphenylsilane was used instead of tetraethoxysilane and the starting conductivity was changed. The results are shown in Table 5. A nearly linear relationship is found between the initial conductivity and the particle size.

[0040]

[Table 5]

Examples 14-16 1600 m of methanol in a glass flask equipped with a stirrer
1, 356 ml of ammonia water (25% by weight) were added, and the reaction solution temperature was kept at 20 ° C. sodium hydroxide (5 mol /
1) The reaction solution was added little by little and the electric conductivity of the reaction solution was adjusted to a predetermined value. To this reaction solution, 0.1% hydrochloric acid was added in advance, and pre-hydrolyzed at room temperature for 2 hours to obtain 163 ml of a methanol solution (18% by weight) of tetraethoxysilane (trade name: ethyl silicate 28, manufactured by Colcoat Chemicals), and tetra-n. -72 ml of a methanol solution (9% by weight) of butoxytitanium (manufactured by Nippon Soda Co., Ltd.) was simultaneously added dropwise at a rate of 25 ml / h to synthesize silica-titania particles. The silica-titania particles were recovered from the reaction solution by centrifugation or spontaneous precipitation, and washed by centrifugation or decantation using a large amount of solvent.

Table 6 shows the results when the electric conductivity of the reaction solution at the start of the reaction was changed. From this, it can be seen that there is a substantially linear relationship between the starting conductivity and the particle size.

[0043]

[Table 6]

Claims (2)

[Claims] 1. When starting the reaction of a reaction solution, when an inorganic oxide particle is produced by hydrolyzing a hydrolyzable organometallic compound in a reaction solution consisting of a hydrolysis catalyst, water, an electrolyte substance, and a solvent. A method for producing inorganic oxide particles, which comprises controlling the particle size by controlling the electrical conductivity of the. 2. By controlling the electrical conductivity at the start of the reaction of the reaction solution when the alkoxysilane is hydrolyzed in the reaction solution consisting of ammonia, water, an electrolyte substance and alcohol to produce silica particles. A method for producing silica particles, which comprises controlling the particle diameter.