JPH04243902A - Production of flocculate of fluoride fine particle - Google Patents

Abstract

PURPOSE:To obtain an aggregate of fluoride fine particles having a narrow particle size distribution and a wide range of utilization by stably predistributing a sparingly soluble fluoride as colloidal particles in water with a peptizer and depositing the dispersion with a coagulant. CONSTITUTION:A sparingly soluble fluoride having 1-10000ppm fluoride ion concentration when converted into a saturated aqueous solution is dispersed in water with a peptizer. A coagulant is then added to the resultant dispersion containing fluoride colloidal particles having 0.005-1mum particle diameter to deposit the fluoride colloidal particles. Thereby, the objective aggregate is obtained. Calcium fluoride, strontium fluoride, barium fluoride, aluminum fluoride, etc., are cited as the sparingly soluble fluoride used. Glyceraldehyde-3- phosphate, alpha-glycerophosphoric acid, beta-glycerophosphoric acid, erythrose-4- phosphate, etc., are cited as the peptizer. Phosphoric acid, carbonic acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, etc., are cited as the coagulant.

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 aggregates of fluoride fine particles having a narrow particle size distribution and a wide range of applications.

0002

[Prior Art and Problems to be Solved by the Invention] Slightly soluble fluorides such as calcium fluoride, barium fluoride, and aluminum fluoride are used as catalysts, refining fluxes, welding materials, etc.
Fire extinguishers, fluorine-containing wastewater purification compositions, oral compositions,
It is widely used as a raw material for pharmaceuticals, etc. When used for these purposes, it is required that the formulation be easy to formulate and have a good effect. For this reason, fluoride is mainly used in the form of fine particles or aggregates of solidified fine particles, and these fine particles preferably have uniform particle shape and particle size, in other words, those with narrow particle size distribution.

[0003] Conventionally, fine particles of these fluorides have been produced by pulverizing the bulk of natural or synthesized by various methods, or, since these fluorides are generally poorly soluble in water, the target poorly soluble fluoride has been produced. It has been produced by removing water from a precipitate obtained by reacting a water-soluble salt containing metal ions constituting the compound with a water-soluble fluoride or hydrofluoric acid. Therefore, it is difficult to control the particle size, and particle size uniformity is maintained by sieving after production. In recent years, unlike these methods, metal hydroxides, oxides, carbonates, etc. that produce the necessary fluoride are made into fine particles of the required particle size and size, and various other particles are added to these. A method for obtaining desired fluoride fine particles by applying fluoride has been developed. For example, fine particles of lime or magnesium oxide,
A method for producing fine particles of calcium fluoride or magnesium fluoride using a combination of hydrofluoric acid or an aqueous ammonium fluoride solution (US Pat. No. 4,120,940);
A method for producing fine particles of calcium fluoride by combining fine particles of calcium carbonate and an aqueous solution of potassium or sodium hexafluorosilicate (U.S.S.R.SU
-81-802185), a method for producing calcium fluoride fine particles by combining an aqueous calcium hydroxide solution, carbon dioxide gas, and hydrofluoric acid (Japanese Unexamined Patent Publication No. 01-083514)
and so on.

However, even with these methods, it is not possible to produce products with a large particle size distribution or small particle size after production, and it is necessary to make the particle shape and particle size of the raw materials uniform in some way before producing fluoride. There are problems such as the need to use certain or dangerous hydrofluoric acid, and the equipment and operations are complicated.

[0005]Therefore, a method for obtaining aggregates of fluoride fine particles free of these drawbacks has been desired.

[0006]

[Means for Solving the Problems] Under these circumstances, the inventors of the present invention have conducted intensive research and have found that a poorly soluble fluoride is stably dispersed in water as colloidal particles using a deflocculant, and this is then dispersed using a flocculant. The present invention has been completed based on the discovery that, by precipitation, a fluoride fine particle aggregate consisting of fine particles with uniform particle shape and narrow particle size distribution can be obtained.

That is, the present invention provides particles with a particle size of 0.005 to 1 μm obtained by dispersing a poorly soluble fluoride having a fluoride ion concentration of 1 to 10,000 ppm in water using a peptizer when made into a saturated aqueous solution. The present invention provides a method for producing fluoride fine particle aggregates, which comprises adding a flocculant to a liquid containing fluoride colloid particles to precipitate fluoride colloid particles.

The poorly soluble fluoride used as a raw material in the present invention has a fluoride ion concentration of 1 to 1 when made into a saturated aqueous solution.
0,000 ppm, specifically fluorides such as calcium fluoride, strontium fluoride, barium fluoride, aluminum fluoride, magnesium fluoride, titanium fluoride, indium fluoride, or lanthanum fluoride. Examples include lanthanoids.

The poorly soluble fluoride raw material is first dispersed as colloidal particles, and the deflocculant used at this time is
For example, carbon number 3 to 1 having one or more phosphoric acid group and/or sulfuric acid group and/or carboxyl group in the molecule
0 monosaccharides, and oligosaccharides in which 2 to 6 of them are linked,
and 3 to 1 carbon atoms having one or more phosphoric acid groups and/or sulfuric acid groups and/or carboxyl groups in the molecule.
A compound selected from the group consisting of 0 polyhydric alcohol and ascorbic acid derivatives is used, specifically, glyceryl aldehyde-3-phosphate, α-glycerophosphate, β-glycerophosphate, erythrose-4-phosphate. acid, ribose-5-phosphate, glucose-1-phosphate, glucose-6-phosphate, inositol monophosphate, inositol hexaphosphate, fructose-1-phosphate, fructose-6-phosphate, fructose-1, Sugar phosphate esters with typical examples being 6-diphosphoric acid and heptulose-7-phosphate; sugar sulfate esters with typical examples being sucrose sulfate; glyceric acid; gluconic acid; ascorbic acid-2-
Examples include ascorbic acid derivatives such as phosphoric acid and ascorbic acid-2-sulfuric acid as typical examples; and salts thereof, and these compounds can be used alone or in combination of two or more types.

The dispersion method is not particularly limited as long as it achieves the purpose of the present invention, but particularly preferred examples include:
Sodium fluoride, potassium fluoride, lithium fluoride,
Aqueous fluorides such as ammonium fluoride, chlorides that provide metal ions constituting the target poorly soluble fluoride, water-soluble salts such as nitrates, sulfates, acetates, glucose-1-phosphates, glycerophosphates, etc. , and a method of mixing the deflocculant described above, then adding water and applying stirring and/or ultrasound; a method of adding the aqueous solution of the water-soluble fluoride and the metal ions constituting the target poorly soluble fluoride. aqueous solution of a water-soluble salt of If it contains metal ions constituting a chemical compound and has high water solubility, it can also be produced using the above method. If produced in this way, an extremely fine and stable fluoride colloid can be obtained. At this time, a wide range of combination ratios (molar ratios) of fluoride ions, metal ions constituting the target poorly soluble fluoride, and deflocculant are allowed. Ion: peptizer = 0.01-100:1:0.01-10
Although 0 is possible, it is preferable that the ratio be as close as possible to the stoichiometric ratio when fluoride ions and metal ions constituting the target poorly soluble fluoride form a salt. It is desirable that the ratio is sufficient to stabilize the colloidal particles, that is, the ratio is as close to 1:1 as possible: metal ions constituting the target hardly soluble fluoride: peptizer=1:1. Considering the above, it is more desirable that the ratio of fluoride ion:metal ion constituting the target hardly soluble fluoride:deflocculant=0.1 to 10:1:0.05 to 20. Of course, among these combinations, if the ratio of fluoride ions and metal ions constituting the target poorly soluble fluoride deviates from the stoichiometric ratio when forming a salt,
Free fluoride ions that do not become colloidal particles and metal ions constituting the target poorly soluble fluoride may be present in the composition, but even in this case, these do not impair the effects of the present invention.

The fluorine content in the fluoride colloid liquid is preferably 10 to 100,000 ppm, more preferably 150 to 60,000 ppm.

[0012] To confirm the production of fluoride colloid,
For example, this can be done by the following method.

(1) When comparing the precipitate amount or turbidity of the sample solution and a solution obtained by removing the deflocculant from the sample solution (control solution), the former is smaller than the latter.

(2) Filter the sample solution with a Millipore filter with a pore size of 0.8 μm, and transfer 8 to 9 ml of the filtrate (10 PC bottles) to an ultracentrifuge (Hitachi SCP70H, rotor: SRP70AT, 50000 rpm, 20 hr,
15°C), a precipitate was observed.

(3) When the sample solution was filtered through a Millipore filter and the dynamic light scattering of the filtrate was measured, the result was 0.00.
Particles of 5 to 1μ are detected (DLS-70 manufactured by Otsuka Electronics)
0).

(4) The sample solution was subjected to a transmission electron microscope (
When observing with Hitachi H-7000), 0.005 to 1μ
particles are observed. In addition, as for the observation sample, the sample solution was filtered with a Millipore filter and subjected to hydrophilic treatment (
A sample is placed on a carbon support film prepared by JEOL JFC-1100) and moisture is removed.

[0017] The above-mentioned fluoride colloid particles are generally extremely fine, and the particle size may be about 5 nm. Moreover, surprisingly, the results of the above-mentioned electron microscopy and dynamic light scattering methods revealed that colloidal particles with an extremely narrow particle size distribution were obtained.

The fluoride colloid particles thus obtained are precipitated by adding a flocculant to the colloid solution. This method allows for high purity, fine,
Moreover, aggregates of fluoride fine particles with uniform particle size can be obtained. In contrast, methods conventionally used for other colloid systems, such as centrifugation or ultracentrifugation of colloidal liquids to sediment colloidal particles to obtain aggregates; vacuum drying and heating of colloidal liquids. A method of removing moisture to obtain a dry aggregate by drying, freeze drying or air drying;
A method in which an organic solvent commonly used for crystallization, such as alcohol, hydrocarbon, halogenated hydrocarbon, or ketone, is added to obtain an aggregate; or a method in which a colloidal solution is dialyzed and concentrated using a dialysis membrane to obtain an aggregate. These methods can also be applied, but they all have the problems of being somewhat complicated to operate, and that coexisting water-soluble salts and deflocculants precipitate at the same time, resulting in a decrease in purity.

The flocculant used in the present invention is not particularly limited as long as it achieves the purpose of the present invention, but for example, a water-soluble acid, preferably an acid having a phosphoric acid group or a carbonic acid group,
Among them, phosphoric acid, carbonic acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, and phosphonic acid, and water-soluble salts of these water-soluble acids, such as salts of alkali metals such as sodium, potassium, and lithium, and amines such as ammonia. is preferred.

[0020] In order to precipitate fluoride fine particles by this method, generally, an appropriate amount of the above-mentioned flocculant is mixed into a fluoride colloid solution prepared in advance, and the mixture is left to stand or stirred for a period of time until precipitation is obtained. Just leave it there. The amount of flocculant added is 0 to the slightly soluble fluoride to be precipitated.
．． It is used in an amount of about 0.01 to 1000 equivalents, preferably about 0.05 to 10 equivalents, but when the amount of deflocculant is large, better results can be obtained by using a large amount of flocculant. The production temperature is preferably from 0°C to around 40°C, but different conditions may be used. In addition, the time until precipitation is obtained depends on the type and concentration of fluoride colloid particles, the type and amount of deflocculant,
Although it varies depending on the type and amount of flocculant, experimentally,
Precipitation is completed from immediately after mixing the flocculant to approximately 20 hours later.

The aggregate obtained in the present invention is a colorless precipitate, which can be used as it is, but the supernatant can be removed by decanting or centrifugation, washed with water, and then air-dried, heat-dried, or frozen. If moisture is removed by drying or vacuum drying, a dried aggregate of fluoride fine particles can be obtained. Further, by pulverizing this using a ball mill, mortar, etc., a fine powder of fluoride can be obtained. The powder obtained at this time is composed of fine particles having a constant particle size, and can basically be treated as an aggregate of fine particles and used.

The fluoride fine particle aggregate obtained in the present invention can be analyzed and identified, for example, by the following method.

(1) When a dry sample was measured by powder X-ray diffraction method, only the diffraction line of the target fluoride was obtained, and the diffraction lines of raw material salts, peptizer, and flocculant were not observed. The fluoride has a broad diffraction line, and the particle size estimated from it is almost the same as the original colloidal particle.

(2) When the morphology of the dried sample was observed using a scanning electron microscope, it was found that the sample was an aggregate of fine particles;
Moreover, the diameter of the observed particles is almost the same as that of the original colloidal particles.

(3) When the dried sample is analyzed by Raman spectroscopy, the peak derived from the target fluoride is the main peak, and the peaks from the raw material salt and deflocculant are not observed. However, in this method, a peak due to the added flocculant is also observed.

(4) When conducting elemental analysis of the dried sample,
90 wt% or more is the target fluoride.

The fluoride fine particle aggregate obtained by the method of the present invention has a narrow particle size distribution and a particle size of 0.005.
Since it is as fine as ~1 μm, it is extremely useful as a raw material for catalysts, refining fluxes, welding materials, fire extinguishers, fluorine-containing wastewater purification compositions, oral compositions, pharmaceuticals, etc.

[0028]

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Preparation of fluoride colloid liquid: Sodium fluoride as a water-soluble fluoride as a raw material, a metal salt constituting the target hardly soluble fluoride, and calcium glucose-1-phosphate as a peptizing agent. After mixing with purified water at various concentrations to achieve the predetermined mixing ratio as shown in Table 1, colloid formation was confirmed by precipitate formation when left at room temperature for one day. I wrote it down. Their mixing ratio (
The molar ratio) is fluoride ion:calcium ion:glucose-1-phosphate ion=0.1 to 10:1:1. The total fluorine concentration in the solution is 8 to 60,000 ppm.
It is.

As a control, a peptizer was not used, sodium fluoride was used as the raw water-soluble fluoride, and calcium chloride was used as the metal salt constituting the target hardly soluble fluoride.Fluoride ion: Calcium ion = Precipitate formation was similarly determined with the naked eye for those mixed and dissolved at a ratio of 2:1.

The results are shown in Table 1. Further, the measurement results of dynamic light scattering of the obtained calcium fluoride colloid (F:Ca:G1P=2:1:1) are shown in FIG.

[0032]

[Table 1]

Example 2 In this example, sodium fluoride, calcium chloride, and the sodium salts of various deflocculants shown in Table 2 were mixed in a molar ratio of 2:1:1, and the total fluorine concentration was 500 ppm. Table 2 shows the results obtained by visually observing the formation of colloid in the solution in the same manner as in Example 1 after one day.

[0034]

[Table 2]

From the above results, it is clear that not only glucose-1-phosphate but also various other compounds act as peptizers and produce similar fluoride colloids.

Example 3 This example shows an example of an experiment in which the amount of phosphoric acid that forms a precipitate was investigated.

[0037] 200mM glucose-1-
A fluoride colloid is prepared by mixing 10 ml of a potassium phosphate aqueous solution, 10 ml of a 200 mM calcium chloride aqueous solution, and 20 ml of a 200 mM sodium fluoride aqueous solution, and when potassium phosphate is added thereto,
The point at which precipitate forms was investigated. The results are shown in Table 3.

[0038]

[Table 3]

In this case, the peptizing agent glucose-1-
Since the addition ratio of phosphoric acid was high, a slightly larger amount of potassium phosphate was required, that is, 0.05 equivalent. In addition, when powder X-ray diffraction of the dried precipitate obtained was measured, extremely wide diffraction lines were obtained (Figure 2), and commercially available calcium fluoride powder (Wako Pure Chemical Industries, Ltd.) giving diffraction lines as shown in Figure 3 was obtained. ), it can be seen that it is made up of very small particles.

Example 4 In this example, an example of producing a calcium fluoride fine particle aggregate is shown.

After mixing 1.95 g of glucose-1-calcium phosphate tetrahydrate and 0.44 g of sodium fluoride, add purified water to make 100 ml, irradiate with ultrasound for 5 minutes, and leave for 1 hour to form a colorless and transparent colloid. A liquid was prepared. When 20 ml of this was taken and 0.22 g of potassium phosphate was added, it immediately became cloudy and a precipitate was formed. After leaving it for 1 day, 400
The supernatant was removed by centrifugation at 0 rpm for 10 minutes. After washing twice with purified water and vacuum drying, powder X-ray diffraction gives a broad diffraction line of calcium fluoride, Raman spectroscopy gives a calcium fluoride peak, and scanning electron microscope shows an average particle size of 10 nm. Aggregates of calcium fluoride fine particles were obtained.

Example 5 In this example, an example of producing a strontium fluoride fine particle aggregate is shown.

Glucose-1-phosphate disodium 4
After mixing 18.8 g of hydrate and 5.81 g of potassium fluoride, add 50 ml of purified water and dissolve. Add 7.93 g of strontium chloride and purified water to make 100 ml, and leave for 1 hour to form a colorless and transparent colloid. Prepared. This is 20m
After adding 0.53 g of sodium carbonate to the solution and leaving it for 1 day, it became cloudy and a precipitate was formed. After that, 4000rp
The supernatant was removed by centrifugation at m for 10 min. After washing twice with purified water and heating and drying at 50°C, powder X-ray diffraction gives a broad diffraction line of strontium fluoride, Raman spectroscopy gives a strontium fluoride peak, and scanning electron microscopy gives an average peak of strontium fluoride. An aggregate of fine strontium fluoride particles having a particle size of 12 nm was obtained.

[0044]

Effects of the Invention The method for producing fluoride fine particle aggregates of the present invention comprises a method for producing fluoride fine particle aggregates from a water-soluble fluoride, a water-soluble salt of a metal constituting the target hardly soluble fluoride, and a peptizer, to a particle size of 0. 0
A fluoride colloid liquid having a narrow particle size distribution of 0.5-1 micron is produced, and a flocculant is added thereto to obtain a fluoride fine particle aggregate. Therefore, according to the present invention, it is possible to easily and safely produce a poorly water-soluble fluoride fine particle aggregate consisting of fine particles with a particle size of 0.005-1 micron and a narrow particle size distribution. Can be done.

[Brief explanation of the drawing]

[Figure 1] Figure 1 shows the results of dynamic light scattering measurements of calcium fluoride colloid prepared in Example 1 in which calcium fluoride was dispersed using glucose-1-phosphate as a peptizer. It is a diagram.

FIG. 2 is a powder X-ray diffraction analysis of the dried calcium fluoride fine particle aggregate produced in Example 3.

FIG. 3 shows powder X-ray diffraction of commercially available calcium fluoride powder (manufactured by Wako Pure Chemical Industries, Ltd.).

Claims (4)

[Claims] Claim: 1. A particle size of 0.00 mm obtained by dispersing a poorly soluble fluoride having a fluoride ion concentration of 1 to 10,000 ppm in water using a peptizer when made into a saturated aqueous solution.
A method for producing fluoride fine particle aggregates, which comprises adding a flocculant to a liquid containing fluoride colloid particles of 0.05 to 1 μm to precipitate fluoride colloid particles. [Claim 2] The peptizer is a monosaccharide having 3 to 10 carbon atoms having one or more phosphate groups and/or sulfate groups and/or carboxyl groups in the molecule, and 2 to 6 carbon atoms thereof. selected from the group consisting of bound oligosaccharides, polyhydric alcohols having 3 to 10 carbon atoms having one or more phosphate groups and/or sulfate groups and/or carboxyl groups in the molecule, and ascorbic acid derivatives The method for producing a fluoride fine particle aggregate according to claim 1, wherein the fluoride fine particle aggregate is a compound comprising: 3. The method for producing fluoride fine particle aggregates according to claim 1, wherein the flocculant is selected from the group consisting of water-soluble acids and water-soluble salts thereof. 4. The method for producing a fluoride fine particle aggregate according to claim 1, wherein the flocculant is a water-soluble salt of phosphoric acid or carbonic acid.