JP6779736B2 - Dispersion method and crushing method of particles in slurry - Google Patents

Description

The present invention relates to a method of crushing particles in a suspension of fine particles (hereinafter referred to as slurry) and a method of dispersing agglomerated particles in the slurry.

Devices for pulverizing or dispersing particles in a slurry include a jet mill, a high-pressure homogenizer, a high-shearing device, and a bead mill. Each has its own characteristics, and the model is selected according to the required performance of items such as particle type, final particle size, and slurry viscosity change.

Among these models, the bead mill described in Patent Document 1 and the like uses ceramic particles such as zirconia oxide as crushing media (beads), stirs the slurry and beads in a closed container, and after the treatment. A device that separates beads from a slurry. There are various types of bead mills. As a method of stirring the beads, there are a method of rotating a plurality of pin-shaped protrusions (Patent Document 1) and a method of rotating a plate-shaped stirrer (Patent Document 2). Further, as a method for separating the beads, a method of passing the treated slurry through a screen or a slit to separate the beads, or a method of separating the beads by using centrifugal force in a stirring container (Patent Document 3). is there.

In the bead mill, since the beads act on the particles in the slurry, the particle crushing / dispersing ability is high. For example, if 0.1 to 1 mm beads are used, hard particles (titanium oxide, barium titanate, etc.) of several micrometers can be pulverized to a submicron size. Also, in the dispersion, by using small diameter beads with a diameter of 0.1 mm or less, oxide particles with a particle diameter of several tens of nanometers are agglomerated, and almost a single particle is dispersed and dispersed. It can be distributed. Further, the bead mill can perform a dispersion treatment of relatively soft organic particles to a crushing / dispersion treatment of hard ceramic particles.

On the other hand, in the dispersion of pigments and pigments which are coloring materials for liquid crystals and printing inks, as described in Patent Document 4, crystal particles such as sodium chloride are mixed with an organic solvent and a slurry of particles, and a bead mill, a kneader, etc. Dispersion treatment is performed using a stirring / crushing device such as a homogenizer. After the treatment, sodium chloride particles and the like are dissolved in water and separated.

Japanese Unexamined Patent Publication No. 2008-253928 Japanese Unexamined Patent Publication No. 2003-144950 JP-A-2007-190447 JP-A-2007-041330

As described above, the bead mill is an excellent device, but the beads used for crushing / dispersing have a problem that the surface is slightly peeled off while the treatment is continued. As the beads are peeled off, the beads are worn out, so it is necessary to renew the beads. Further, there is a problem that the particles from which the beads are peeled off (bead fragments) are mixed in the slurry after the treatment. The size of bead fragments is 10 micrometers or less, often 1 micrometer or less, and screens and centrifuges cannot separate them all.

In many cases, it is okay for a small amount of inseparable bead debris (often zirconium oxide) to be mixed into the product slurry, but for high-purity electronic component raw materials, coloring materials, pharmaceuticals, etc. However, even a small amount of the mixture causes problems such as deterioration of product performance. In particular, in pharmaceutical products, contamination with fine foreign substances may cause health hazards, and thus contamination with such bead fragments is strongly avoided.

On the other hand, the salt milling method has an advantage that the problem of bead contamination does not occur because the dispersion media (sodium chloride or the like) is dissolved in a solvent such as water and separated after the dispersion treatment. However, in the salt milling method, the slurry solvent is limited to a certain organic solvent or the like. Therefore, there is a problem that it cannot be applied to general pulverization / dispersion treatment because it cannot be utilized for dispersion treatment in water. Further, since the dispersion medium is soft, it cannot be processed by applying strong shearing, so that there is a problem that only processing of soft particles or processing with a low degree of dispersion can be performed.

In this way, in both the pulverization and dispersion treatment using a bead mill and the salt milling method, high-purity barium titanate particle dispersion treatment, nano-sized pharmaceutical raw materials, coloring materials, etc. can be subjected to high-purity and high-purity pulverization and dispersion treatment. could not. Therefore, a new method for solving these technical problems has been sought.

(1) A metal oxide or carbon oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in an acid, the metal oxide or carbon oxide. The particles in the slurry having an average particle size larger than the average particles in the slurry to be treated are mixed with the slurry and stirred to pulverize and / or disperse the particles in the slurry, and then further. By adding an acidic substance to the slurry, the beads and bead fragments remaining in the slurry are dissolved and treated , and as the metal oxide or carbon oxide, barium carbonate, calcium carbonate, magnesium carbonate, magnesium oxide, etc. When using lead oxide or lead carbonate beads, the beads are dissolved by adding hydrochloric acid, nitrate, ammonium chloride or ammonium nitrate to adjust the pH of the slurry to 2.0 to 5.5. It is a method of dispersing particles in a slurry and a method of pulverizing the particles.

(2) A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the metal oxide or charcoal oxide. The average particle size of the particles in the slurry is larger than the average particle of the particles in the slurry. The stirring medium and the slurry are mixed and stirred to crush or / or disperse the particles in the slurry. Later, the stirring media is separated from the treated slurry, and an acidic substance is added to the slurry to dissolve the stirring media remaining in the slurry . Metal oxides or carbon dioxide are used. When beads of barium carbonate, calcium carbonate, magnesium carbonate, magnesium oxide, lead oxide, or lead carbonate are used as the compound, acetic acid or acetate is added to dissolve the beads to dissolve the beads.

(3) A metal oxide or carbon oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the metal oxide or carbon oxide. The particles in the slurry were pulverized and / or dispersed by mixing and stirring the stirring medium, which is a particle having an average particle size larger than the average particles of the particles in the slurry to be treated. Later, the stirring media is separated from the treated slurry, and an acidic substance is further added to the slurry to dissolve the stirring media remaining in the slurry, which can be used as a raw material for foods or pharmaceuticals. In the case of treatment, the particles in the slurry are crushed and / or dispersed by rotating the stirrer in the container using beads made of magnesium oxide, magnesium carbonate, or calcium carbonate, and then the treatment is performed. The beads are separated, and acetic acid or an acetate is added to dissolve the beads to dissolve the beads.

(4) A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the metal oxide or charcoal oxide. The particles in the slurry were pulverized and / or dispersed by mixing and stirring the stirring medium, which is a particle having an average particle size larger than the average particles of the particles in the slurry to be treated. Later, the stirring media is separated from the treated slurry, and an acidic substance is further added to the slurry to dissolve the stirring media remaining in the slurry . Metal coal oxides are beaded. After adding carbon dioxide to the slurry to be treated, the slurry is treated.

By using the method for dispersing particles in the slurry and the method for pulverizing the particles in the slurry of the present invention, it is possible to prevent contamination by the bead component in the pulverization / dispersion treatment in which there is a problem of contamination of raw materials by bead fragments in the prior art. As a result, in raw material powders such as electronic device materials, it is possible to prevent the performance of the device from deteriorating due to contamination of zirconium oxide or the like caused by bead fragments. Further, in the coloring material, it is possible to prevent the occurrence of color unevenness due to impurities.

Drugs (nano-drugs) produced by crushing raw material powder to submicrons or less may cause side effects due to contamination of bead fragments, so contamination by bead fragments is extremely disliked. At present, there is no pulverization method corresponding to the production of nano-drugs, but the method of the present invention can solve the problem of bead fragment contamination.

It is the schematic of the bead mill for performing the crushing treatment and the dispersion treatment of the particles in a slurry.

The present invention can be applied to a process of pulverizing and / or dispersing particles in a slurry by stirring a slurry containing particles of metal oxide or carbonic acid oxide and fine particles. As an apparatus for the treatment, an apparatus such as a bead mill or a kneader that agitates the slurry such as a disperser or a kneader is used.

In the present specification, as a typical device for carrying out the present invention, an example using a so-called bead mill will be described. There are several types of bead mills, one of which is shown in FIG. The bead mill basically has a rotating body (rotor 4) that agitates a mixture of slurry and beads in a cylindrical barrel (container) composed of a barrel side surface 1, a lower end surface 2, and an upper end surface 3. It is a thing. The slurry is supplied from the slurry inlet 5 installed on one end surface (lower end surface 2 in FIG. 1) of the barrel, and the rotor 4 is rotated at high speed to stir the slurry together with the beads inside the barrel 1. .. Although it depends on the target slurry particles, the rotation condition of the rotor 4 is about 3 to 40 m / sec. Inside the barrel, as the slurry swirls, shearing force and collision force are generated by the beads, and the particles in the slurry are crushed or dispersed. Here, dispersion means that secondary particles formed by aggregating a plurality of single particles (primary particles) are divided into single particles.

When the treated slurry passes through the bead separation centrifuge 6 inside the barrel, the beads are separated, and the slurry further passes through the rotor 4 and the rotation axis of the centrifuge 6 to form the slurry. It is discharged to the outside of the device from the outlet 7. The rotor 4 and the centrifuge 6 are rotated by an electric motor. Incidentally, the bead diameter is generally several tens to 1,000 times larger than that of the slurry particles. The discharged slurry is returned to the supply tank and supplied to the bead mill again.

The bead mill for carrying out the present invention does not necessarily have to be the one shown in FIG. 1, and any of various bead mills may be used. In FIG. 1, the rotation axes of the bead mill are arranged vertically, but they may be arranged horizontally. The shape of the rotor 4 for stirring the beads may be a plate-shaped stirrer or a fin-shaped rotor as long as the slurry and the beads can be effectively stirred. In FIG. 1, the centrifuge 6 is used for bead separation, but a screen type or a slit type may be used. Further, the beads may be separated outside the device.

Generally, in the slurry grinding process, particles of several micrometers to submicrons are processed and relatively large beads of 0.2 to 3 mm are used. In the dispersion treatment, agglomerates (secondary particles) of relatively small particles of submicrons to several tens of nanometers are treated. The beads used for the dispersion treatment are generally 15 to 200 micrometers.

In the prior art, it is common to use beads made of zirconia oxide. On the other hand, in the present invention, an oxide or carbonic acid oxide which is not soluble in neutral water but is soluble in acid at room temperature (10 to 70 ° C.) is used as beads. As an index for selecting a substance as a raw material for beads, a substance having a solubility in water at 25 ° C. of 1 cm ³ / liter or less is preferable. In general bead mill operation, the bulk volume of the beads is 50 to 70% of the bead mill volume, and the filling rate of the bead aggregate is 60 to 65%. Therefore, the true volume of the beads is 30 to 30 to the bead mill volume. It is 45%. On the other hand, the slurry volume is determined by the volume of the entire processing system including the one in the supply tank, and is 3 to 5 times the volume of the bead mill. That is, the water volume is 7 to 15 times the true volume of the beads. If the amount dissolved in water during the treatment exceeds 3% of the amount of beads, the shape and diameter of the beads change, and the pulverization / dispersion performance changes. Therefore, dissolution of beads of 3% or more is not desirable. Taken together, the bead dissolution should be 2 cm ³ or less per liter of water. Considering the increase in the amount of dissolution when the temperature of the slurry rises during the treatment, the solubility (25 ° C.) needs to be 1 cm ³ or less per liter. When metal charcoal oxide is used as beads, it is preferable to add carbon dioxide gas to the slurry. By adding carbon dioxide gas, dissolution of calcium carbonate, magnesium carbonate, etc. can be suppressed.

In order to convert the solubility expressed in volume per liter to normal solubility, it is necessary to convert it to g / liter in consideration of the true specific gravity of the substance. For example, the calcium carbonate, since the specific gravity of 2.93 g / cm ^3, acceptable solubility is a condition of the present invention (1 cm ³ / l) is 0.34 g / cm ^3. On the other hand, the actual solubility is 0.015 g / liter (literature value: 0.00015 mol / liter), and the actual solubility is about 1/23 of the allowable solubility, which satisfies the condition of the present invention. Further, it is a condition of the bead raw material of the present invention that it can be dissolved even with a small amount of acid, that is, a pH relatively close to 7. Other substances that satisfy this condition include magnesium oxide, magnesium carbonate, barium carbonate, and lead oxide.

The effectiveness as beads is also determined by the hardness. The harder the substance, the larger the beads can be produced. In that sense, for example, relatively hard magnesium oxide or lead oxide can produce relatively large beads up to about 3 mm. With slightly soft calcium carbonate or magnesium carbonate, the beads are relatively small, about 1 mm or less.

The slurry particles to be the subject of the present invention are generally about 30 nanometers to 1 micrometer in the dispersion treatment, and the bead diameter is 15 to 100 micrometers. Further, in the pulverization treatment, the slurry particles are generally about 1 to 100 micrometers, and the bead diameter is 0.1 to 5 mm. Examples of the substance species of the slurry particles include oxides such as titanium oxide, barium titanate, and red iron oxide, colorant pigments, and organic substances such as organic chemicals.

After the pulverization / dispersion treatment is completed, an acid substance is added to the slurry discharged from the bead mill. Add an acidic substance (additive agent) to dissolve the beads. As the additive agent, one that does not react with or has little reaction with the particles in the slurry and that easily dissolves the substance of the beads is used. When the beads are separated from the slurry discharged from the bead mill, (1) the amount of bead fragments is small (less than a few tenths of the slurry particles), and (2) the bead fragment particle size is small (mostly 10). Since it is (micrometer or less), bead fragments dissolve in a short time even with diluted acid. Therefore, it is a condition for effectively carrying out the present invention that the beads are separated from the slurry before the dissolution treatment.

When the particles in the slurry are resistant to acid, hydrochloric acid, nitric acid, or salts of these acids may be used as the additive agent. If the pH is too high, it will take time to dissolve the beads. Low pH damages the slurry powder. Therefore, when processing a slurry of a relatively stable substance such as titanium oxide, aluminum oxide, or graphite, it is preferable to set the pH to an appropriate value of 2 to 5.5. When it is necessary to suppress the reaction of slurry particles, the pH is preferably in the range of 3.5 to 5.5. When the bead separation operation of the slurry is performed before the dissolution treatment, a small amount of hydrochloric acid or nitric acid may be used, and the pH can be relatively high, about 5. Ammonium hydrochloride or ammonium nitrate can also be used if the pH is not desired to be lowered too much. If ammonium hydrochloride or ammonium nitrate is used, beads can be dissolved even at a pH closer to 7 (4 to 6).

In the case of beads of magnesium, calcium, barium, lead oxide or carbonic acid oxide, it is preferable to use an organic acid as an additive agent. In particular, with the use of acetic acid or acetate, dissolution of these substances occurs quickly. Acetic acid and acetate may be mixed and used. As the acetate salt used in the present invention, those having high solubility such as sodium acetate and potassium acetate are preferable. The use of acetic acid as an additive has the effect of dissolving only bead fragments because acetic acid is a weak acid and is difficult to react with many organic substances and general oxides such as titanium oxide and aluminum oxide. In addition, acetic acid is a food, and even if it remains in the slurry in the treatment of raw materials for foods and chemicals, it has the effect of not causing harmful side effects to the human body. Therefore, a combination of calcium carbonate, magnesium carbonate, magnesium oxide beads, which are compounds of potassium and magnesium, which are elements that are not harmful to the human body, and an acetic acid or acetate-added drug, can be used for dispersion treatment of nano-drugs and health foods. Good to apply.

使用したビーズは、酸化マグネシウム、炭酸マグネシウム、及び炭酸カルシウムであった。処理対象のスラリーは、酸化チタン（一次粒子径６５ナノメートル、二次粒子径１８９ナノメートル）、グラファイト（二次粒子径５４マイクロメートル）、乳酸・グリコール酸共重合体（PLGA、粒子径５５マイクロメートル）であった。実験条件と結果を表１に示す。表には、処理条件、分散結果、ビーズ分離の有無、処理後ビーズ混入量、溶解処理後のビーズ混入量などを記載した。また、各々の処理の比較例として、酸化ジルコニウムのビーズでの実験例を記載した。ビーズ破片溶解処理は、４０℃で２０分間、スラリーを攪拌して行った。 The present invention was carried out using the apparatus of FIG. The experimental device had a barrel volume of 500 cm ³ , and the peripheral speed of the rotor could be changed in the range of 2 to 40 m / sec.

The beads used were magnesium oxide, magnesium carbonate, and calcium carbonate. The slurry to be treated is titanium oxide (primary particle diameter 65 nanometers, secondary particle diameter 189 nm), graphite (secondary particle diameter 54 μm), lactic acid / glycolic acid copolymer (PLGA, particle diameter 55 μm). It was (meters). The experimental conditions and results are shown in Table 1. In the table, treatment conditions, dispersion results, presence / absence of bead separation, amount of beads mixed after treatment, amount of beads mixed after dissolution treatment, etc. are described. In addition, as a comparative example of each treatment, an experimental example using zirconium oxide beads was described. The bead fragment dissolution treatment was carried out by stirring the slurry at 40 ° C. for 20 minutes.

In Example 1, a titanium oxide slurry was treated with 30 micrometer beads of magnesium oxide. After the dispersion treatment, the secondary particle size of titanium oxide was 77 nanometers, and the dispersion state was sufficient. The beads mixed after the treatment were 2.1% by mass of the titanium oxide powder as a raw material. After this treatment, hydrochloric acid was added to the slurry at a ratio of 0.004 mol / liter to adjust the pH to 2.5, and the mixture was stirred at 40 ° C. for 20 minutes. As a result, magnesium oxide was not detected in the slurry after the dissolution treatment, and titanium oxide was not chemically damaged. On the other hand, in the treatment of the zirconium oxide beads of Comparative Example 1, the bead mixing ratio was 1.1% by mass, and the ratio did not change even in the hydrochloric acid treatment.

In Example 2, a graphite slurry was treated with 100 micrometer beads of magnesium carbonate. After the dispersion treatment, the secondary particle size of graphite was 195 nanometers, which was a sufficiently dispersed state. The beads mixed after the treatment were 2.8% by mass of the graphite powder as a raw material. Ammonium nitrate was added to the slurry after this treatment at a ratio of 0.01 mol / liter to adjust the pH to 4.8, and the mixture was stirred at 40 ° C. for 20 minutes. As a result, magnesium oxide in the slurry after the dissolution treatment was not detected. There was no chemical damage to graphite. On the other hand, in the treatment of the zirconium oxide beads of Comparative Example 2, the bead mixing ratio was 1.8% by mass, and the ratio did not change even in the acid treatment.

In Example 3, the PLGA slurry was treated with 60 micrometer beads of calcium carbonate. In addition, 100 cm ³ of carbon dioxide gas was bubbled per minute into the supply tank (3 liters) holding the slurry. After the dispersion treatment, the particle size of PLGA became 220 nanometers, which was a sufficiently dispersed state. The beads mixed after the treatment were 1.2% by mass of the PLGA powder as a raw material. A 1: 1 (molar ratio) mixture of acetic acid and sodium acetate was added to the post-treatment slurry at a ratio of 0.005 mol / liter, and the mixture was stirred at 40 ° C. for 20 minutes. As a result, calcium carbonate in the slurry after the dissolution treatment was not detected. Also, PLGA] had no chemical damage. On the other hand, in the treatment of the zirconium oxide beads of Comparative Example 3, the bead mixing ratio was 0.9% by mass, and the ratio did not change even in the acid treatment.

The method for crushing / dispersing a slurry according to the present invention is for crushing / crushing raw material powder slurries such as ceramics, carbon nanotubes, cellulose nanofibers, pigments, inks, paints, dielectrics, magnetic materials, pharmaceuticals, foods, and lithium ion battery electrodes. Suitable for dispersion.

1 ・ ・ Barrel side surface 2 ・ ・ Lower end surface 3 ・ ・ Upper end surface 4 ・ ・ Rotor 5 ・ ・ Slurry inlet 6 ・ ・ Centrifuge 7 ・ ・ Slurry outlet

Claims (5)

A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the particles of the metal oxide or charcoal oxide A stirring medium having an average particle size larger than the average particles of the particles in the slurry to be treated and the slurry are mixed and stirred to pulverize and / or disperse the particles in the slurry, and then the treatment is performed. By performing a separation operation of the stirring media from the subsequent slurry and further adding an acidic substance to the slurry, the stirring media remaining in the slurry is dissolved .
When barium carbonate, calcium carbonate, magnesium carbonate, magnesium oxide, lead oxide, or lead carbonate beads are used as the metal oxide or carbon oxide, hydrochloric acid, nitrate, ammonium chloride, or ammonium nitrate is added when the beads are dissolved. A method for dispersing particles in a slurry and a method for pulverizing the beads, which comprises dissolving the beads by setting the pH of the slurry to 2.0 to 5.5 . A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the particles of the metal oxide or charcoal oxide A stirring medium having an average particle size larger than the average particles of the particles in the slurry to be treated and the slurry are mixed and stirred to pulverize and / or disperse the particles in the slurry, and then the treatment is performed. By performing a separation operation of the stirring media from the subsequent slurry and further adding an acidic substance to the slurry, the stirring media remaining in the slurry is dissolved.
When barium carbonate, calcium carbonate, magnesium carbonate, magnesium oxide, lead oxide, or lead carbonate beads are used as the metal oxide or carbon oxide, acetic acid or acetate is added to dissolve the beads to dissolve the beads. dispersion method and pulverizing method features and be away rally in the particles to be. A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the particles of the metal oxide or charcoal oxide A stirring medium having an average particle size larger than the average particles of the particles in the slurry to be treated and the slurry are mixed and stirred to pulverize and / or disperse the particles in the slurry, and then the treatment is performed. By performing a separation operation of the stirring media from the subsequent slurry and further adding an acidic substance to the slurry, the stirring media remaining in the slurry is dissolved.
When processing raw materials for foods or pharmaceuticals, beads made of magnesium oxide, magnesium carbonate, or calcium carbonate are used to crush and / or disperse particles in the slurry by rotating a stirrer in a container. after processing, performs bead separation process, further dispersion method and pulverizing method features and be away rally in the particles that the addition of acetic acid or acetate to dissolve the beads for the bead lysis. A metal oxide or charcoal oxide having a solubility in neutral water at 25 ° C. of 1 cm ³ / liter or less in terms of solid volume and being soluble in acid, and the particles of the metal oxide or charcoal oxide A stirring medium having an average particle size larger than the average particles of the particles in the slurry to be treated and the slurry are mixed and stirred to pulverize and / or disperse the particles in the slurry, and then the treatment is performed. By performing a separation operation of the stirring media from the subsequent slurry and further adding an acidic substance to the slurry, the stirring media remaining in the slurry is dissolved.
As bead material, in the case of using a carbonate of a metal, the dispersion method and pulverizing method features and be away rally in the particles treating the slurry with added carbon dioxide at a bead mill. A process of crushing or / or dispersing the particles in the slurry is performed with a bead mill, and after a separation operation of the stirring medium from the slurry is performed, an acidic substance is added to the slurry discharged from the bead mill to be combined with the slurry. The method for dispersing particles in a slurry and a method for pulverizing the particles in the slurry according to any one of claims 1 to 4, wherein the stirring media and the fragments of the stirring media remaining in the slurry discharged to the outside of the bead mill are dissolved and treated.

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