JP6984430B2 - Clay particles and their manufacturing method - Google Patents

Description

The present invention relates to clay particles and a method for producing the same, and more specifically, it has excellent handleability, powder properties, and fluidity, and is expected to be used as a carrier, a filler, an auxiliary agent, and the like. It relates to clay particles and a method for producing them.

Inorganic oxidizing compounds such as zeolite, silica, alumina and clay are being studied as catalyst materials by utilizing the large specific surface area. Among them, clay minerals such as montmorillonite and hectorite have an ion exchange ability with cations, and therefore have undergone a modification reaction for ion exchange with specific cations, and are being studied as solid powder catalysts (for example, non-clay minerals). See Patent Document 1).

In addition, since the particle size of clay used as a catalyst affects the catalyst performance, various studies have been conducted to adjust the particle size. For example, a pulverization method using a jet mill and a granulation method using a spray dryer. Etc. have been proposed (see, for example, Patent Document 1).

Journal of the Japanese Society of Ion Exchange, Vol. 24 (2013) No. 1, p. 1-7

Japanese Unexamined Patent Publication No. 2015-25035

Granulation by the spray-drying method is widely used as a method for adjusting the particle size of particles because it is possible to prepare spherical particles having a high bulk density. The particle size of the particles obtained by the spray-drying method is determined by the concentration of the undiluted solution and the size of the droplets generated during spraying. Therefore, in order to obtain fine particles, it is necessary to reduce the concentration of the stock solution or make the droplets as small as possible. Industrially, thinning the undiluted solution reduces productivity, so it is common to make fine droplets at the highest possible concentration.

However, when clay is dispersed in water, it becomes a colloidal liquid (sol) at a low concentration of about 1 to 2% by weight, and at a higher concentration, it gels and the viscosity increases significantly, and the fluidity of the liquid is lost. Liquid transfer becomes difficult, and spray drying itself becomes impossible.

Therefore, it is expected to provide uniform and fine spherical particles and a method for efficiently producing them.

As a result of diligent studies to solve the above problems, the present inventors have excellent clay particles having a specific compound in a specific ratio and a specific median diameter with respect to 100 parts by weight of smectite-based clay mineral. It has been found that the above-mentioned characteristics are exhibited, and the present invention has been completed.

That is, the present invention is a particle containing 5 parts by weight or more and 20 parts by weight or less of the compound represented by the following general formula (1) and / or (2) with respect to 100 parts by weight of a smectite-based clay mineral, and has a median diameter. The present invention relates to clay particles having a size of 4 μm or more and 20 μm or less, and a method for producing the same.

(In the formula, R ¹ represents an alkyl group, an aryl group, an alkylamino group or a halogen having 1 to 20 carbon atoms, R ² represents an alcohol, hydrogen or a halogen, and M ^{1 to} M ⁴ represent hydrogen independently. Represents lithium, sodium or potassium.)

(In the formula, M ^{5 to} M ⁸ independently represent lithium, sodium or potassium, respectively.)
Hereinafter, the present invention will be described in detail.

The clay particles of the present invention are particles containing 5 parts by weight or more and 20 parts by weight or less of the compounds represented by the above general formulas (1) and / or (2) with respect to 100 parts by weight of smectite-based clay minerals. The median diameter has a range of 4 μm or more and 20 μm or less.

Examples of smectite-based clay minerals constituting the clay particles of the present invention include montmorillonite, hectorite, bidelite, nontronite, saponite, etc. Among them, montmorillonite and hectorite are easy to obtain and use. Is preferable, and synthetic hectorite is more preferable because it is easy to maintain a sol state even at a high concentration and it is possible to efficiently form fine clay particles when dispersed in water.

Compound represented by the general formula (1) as R ¹ is an alkyl group having 1 to 20 carbon atoms, an aryl group, an alkylamino group or a halogen, as R ² is an alcohol, hydrogen or halogen, M ¹ each independently hydrogen as ~M ^4, are those of lithium, sodium or potassium. Specific examples thereof include sodium etidronate, sodium alendronate, sodium risedronate, and sodium clodronic acid. Further, the compound represented by the general formula (2) are those wherein each lithium independently, sodium or potassium as M ⁵ ~M ^8. Specific examples thereof include tetrasodium etidronate (sometimes referred to as 1-hydroxyethane-1,1-tetrasodium diphosphonate), tetralithium etidronate, and dilithium disodium etidronate.

The clay particles of the present invention contain 5 parts by weight or more and 20 parts by weight or less of the compounds represented by the above general formulas (1) and / or (2) with respect to 100 parts by weight of the smectite-based clay mineral. Here, when the content of the compound is less than 5 parts by weight or exceeds 20 parts by weight, it becomes difficult to achieve a fine particle size and a uniform particle size.

The clay particles of the present invention have a median diameter of 4 μm or more and 20 μm or less. Here, when the median diameter is less than 4 μm or exceeds 20 μm, the powder characteristics and handleability are inferior. The median diameter referred to in the present invention refers to a particle size (d ₅₀ ) having a cumulative diameter of 50% on a volume basis. Further, the geometric standard deviation (σ) defined by the log (d ₈₄ / d _{50 ) can be obtained from the particle size (d 84} ) having a cumulative diameter of 84% on a volume basis as _{in d 50.} The clay particles of the present invention are particularly excellent in uniformity and excellent in their characteristics, so that σ is preferably 0.15 or less. The method for measuring the particle size is not particularly limited, and examples thereof include a method for measuring using a laser diffraction / scattering type particle size measuring device.

Further, although the clay particles of the present invention are spherical, they may have some dents or distortions, or may be hollow or ring-shaped particles. At that time, circularity is known as an index showing how spherical the particles are. Here, the circularity is an index defined by (perimeter of a circle having the same projected area) / (perimeter of a particle), and the closer it is to 1, the closer it is to a circle. If the proportion of particles with a circularity of 1 is 100%, then these particles can be considered to be true spheres. As a method for measuring the circularity, for example, a method of taking an SEM photograph of particles, projecting them on a very fine grid, and measuring the grid area of the projected portion and its outer circumference can be mentioned. As mentioned above, if there are dents or distortions, or if the particles are hollow or ring-shaped, the circularity tends to be small. The clay particles of the present invention preferably have a ratio of particles having a circularity of 0.9 to 1 of 90% or more of the total number of particles.

As the method for producing the clay particles of the present invention, any method may be used as long as the clay particles can be produced, and the clay particles are spray-dried by a spray dryer known as an efficient method for producing the particles. The manufacturing method can be mentioned.

Hereinafter, as an example of a preferable manufacturing method, an example of a manufacturing method by spray drying will be described.

When spray-drying, a method of supplying as a sol containing a smectite-based clay mineral and the compound represented by the above general formulas (1) and / or (2) and spray-drying can be mentioned. At that time, as the solvent constituting the sol, water can be mentioned, and further, distilled water, ion-exchanged water, tap water and the like can be mentioned as the water. The sol preferably contains smectite-based clay minerals at a concentration of 15% by weight or more and 40% by weight or less because it enables efficient production of clay particles. The temperature at which the sol is supplied is preferably 40 ° C. or higher because the viscosity of the sol is low and stable when the sol is sent, and stable particles can be efficiently produced. In particular, it is preferably 40 ° C. or higher and 80 ° C. or lower.

Examples of the spray dryer method include a four-fluid nozzle type, a two-fluid nozzle type, a rotary atomizer type, an ultrasonic nozzle type, a pressure nozzle type, and the like, and among them, fine particles can be efficiently obtained. Therefore, a four-fluid nozzle type and a two-fluid nozzle type are preferable.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide fine spherical clay particles which are excellent in handleability, powder properties and fluidity and are expected to be used as various uses as carriers, fillers, auxiliaries and the like, and methods for producing the same.

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

The preparation and evaluation methods in Examples and Comparative Examples are shown below.

~ Spray dryer four-fluid nozzle type (manufactured by Fujisaki Electric Co., Ltd., (trade name) MDP-050).

~ Particle size measurement ~
Ethanol was measured as a dispersant using a Microtrack particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., (trade name) MT3300).

~ Circularity ~
Using a microscope (manufactured by JEOL Ltd., (trade name) FE-SEM JSM-7100F), the surface is osmium-coated, and transparent graph paper at 0.5 mm intervals is overlaid on the SEM photograph taken at 2000 times, and the particles overlap. The grid of graph paper was filled, and the grid area and outer diameter were measured and calculated.

Production Example 1
Dissolve 0.743 kg of sodium hydrogen carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) in 5.387 kg of water, and while cooling in an ice bath, 1-hydroxyethane-1,1-diphosphonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 60% solution 0. 759 kg was added slowly. After the addition was completed, the mixture was stirred for 30 minutes to obtain 6.5 kg of a 10 wt% aqueous solution of tetrasodium etidronate (1-hydroxyethane-1,1-tetrasodium diphosphonate).

Example 1
2.7 kg of water at 40 ° C. and 1.3 kg of the tetrasodium ethidronate aqueous solution produced in Production Example 1 were mixed, and 1 kg of dried synthetic hectorite (manufactured by Big Chemie Japan, (trade name) Laponite RD) was added thereto. In addition, by stirring for 2 hours while maintaining 40 ° C., 5.0 kg of clay sol having 20% by weight of hectorite and 13 parts by weight of tetrasodium ethidronate with respect to 100 parts by weight of hectorite was prepared. While maintaining 40 ° C., this clay sol was sent at a rate of 25 mL / min and air at a rate of 35 NL / min to a spray dryer having an inlet temperature set to 200 ° C. to obtain 0.92 kg of clay particles.

When the particle size of the clay particles was measured, the median diameter was 11.2 μm and σ was 0.15. The proportion of particles having a circularity of 0.9 to 1 was 95%.

Example 2
3.875 kg of water at 40 ° C. and 0.375 kg of the tetrasodium etidronate aqueous solution produced in Production Example 1 were mixed, and 0.75 kg of the same synthetic hectorite used in the dried Example 1 was added thereto, and 40 was added. By stirring for 2 hours while maintaining the temperature, 5.0 kg of clay sol having 15% by weight of hectorite and 5 parts by weight of tetrasodium etidronate with respect to 100 parts by weight of hectorite was prepared. While maintaining 40 ° C., this clay sol was sent at a rate of 20 mL / min and air at a rate of 20 NL / min to a spray dryer having an inlet temperature set to 200 ° C. to obtain 0.70 kg of clay particles.

When the particle size of the clay particles was measured, the median diameter was 4.4 μm and σ was 0.13. The proportion of particles having a circularity of 0.9 to 1 was 98%.

Example 3
0.84 kg of water at 75 ° C. and 2.56 kg of the tetrasodium etidronate aqueous solution produced in Production Example 1 were mixed, and 1.6 kg of the same synthetic hectorite used in Example 1 was added to 75. By stirring for 2 hours while maintaining the temperature state, 5.0 kg of clay sol having 32 parts by weight of hectorite and 16 parts by weight of tetrasodium etidronate with respect to 100 parts by weight of hectorite was prepared. The clay sol was sent at a rate of 20 mL / min and air at a rate of 30 NL / min to a spray dryer having an inlet temperature set to 200 ° C. to obtain 1.4 kg of clay particles.

When the particle size of the clay particles was measured, the median diameter was 15.4 μm and σ was 0.14. The ratio of particles having a circularity of 0.9 to 1 was 91%.

Comparative Example 1
When 0.5 kg of the same synthetic hectorite used in Example 1 was added to 4.5 kg of water at 60 ° C., the whole gelled and could not be stirred, and the liquid could not be sent to the spray dryer.

Comparative Example 2
To 6.474 kg of water at 20 ° C., 0.218 kg of sodium pyrophosphate decahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and then 1.0 kg of the same synthetic hectorite used in Example 1 was added, and the mixture was stirred for 24 hours. By doing so, 7.692 kg of clay sol having 13 parts by weight of hectorite and 13 parts by weight of sodium pyrophosphate with respect to 100 parts by weight of hectorite was prepared. The clay sol was sent at a rate of 20 mL / min and air at a rate of 30 NL / min to a spray dryer having an inlet temperature set to 200 ° C. to obtain 0.93 kg of clay particles.

When the particle size of the clay particles was measured, the median diameter was 3.6 μm and σ was 0.17. The proportion of particles having a circularity of 0.9 to 1 was 88%.

Comparative Example 3
To 6.474 kg of water at 75 ° C., 0.218 kg of sodium pyrophosphate decahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and then 1.0 kg of the same synthetic hectorite used in Example 1 was added, and the temperature was 75 ° C. After stirring for 24 hours while maintaining the sol, a highly viscous sol was formed, and the liquid could not be sent to the spray dryer.

Comparative Example 4
An attempt was made to prepare a clay sol in the same manner as in Example 3 except that water at 25 ° C. was used instead of water at 75 ° C., but the viscosity of the sol increased significantly and a large amount of lumps were generated. Stirring was continued for another 8 hours, but some lumps remained. After collecting the lumps, clay sol was sent at a rate of 20 mL / min and air was sent at a rate of 30 NL / min to a spray dryer having an inlet temperature set to 200 ° C., and 0.7 kg of clay particles were obtained.

When the particle size of the clay particles was measured, the median diameter was 3.4 μm and σ was 0.21. The proportion of particles having a circularity of 0.9 to 1 was 89%.

The clay particles of the present invention are excellent in handleability, powder properties, and fluidity, and are expected to be used in various ways as carriers, fillers, auxiliaries, and the like.

Claims (5)

Particles containing 5 parts by weight or more and 20 parts by weight or less of the compound represented by the following general formula (1) and / or (2) with respect to 100 parts by weight of smectite clay mineral, and have a median diameter of 4 μm or more and 20 μm or less. Clay particles characterized by being.

(In the formula, R ¹ represents an alkyl group, an aryl group, an alkylamino group or a halogen having 1 to 20 carbon atoms, R ² represents a hydroxyl group , hydrogen or a halogen, and M ^{1 to} M ⁴ are independent hydrogens. , Lithium, sodium or potassium.)

(In the formula, M ^{5 to} M ⁸ independently represent lithium, sodium or potassium, respectively.) The clay particle according to claim 1, wherein the geometric standard deviation of the particle size is 0.15 or less. The clay particle according to claim 1 or 2, wherein the ratio of the particles having a circularity of 0.9 to 1 is 90% by weight or more among all the particles. A method for producing clay particles, which comprises spray-drying a sol containing a smectite-based clay mineral heated to 40 ° C. or higher and a compound represented by the following general formulas (1) and / or (2).

(In the formula, R ¹ represents an alkyl group, an aryl group, an alkylamino group or a halogen having 1 to 20 carbon atoms, R ² represents a hydroxyl group , hydrogen or a halogen, and M ^{1 to} M ⁴ are independent hydrogens. , Represents lithium, sodium or potassium.)

(In the formula, M ^{5 to} M ⁸ independently represent lithium, sodium or potassium, respectively.) The method for producing clay particles according to claim 4, wherein the concentration of the hectorite-based clay mineral in the sol is 15% by weight or more and less than 40% by weight.