JP2006192389A - Manufacturing method of inorganic spherical body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an inorganic spherical body having a large particle size with a mean particle diameter of 100 μm or more. <P>SOLUTION: The manufacturing method of the inorganic spherical body passes through; a process for forming a W/O type emulsion by dispersing an aqueous liquid containing an inorganic compound into an organic liquid; a process for adding a metal alkoxide to the W/O type emulsion; and a process for solidifying the aqueous liquid containing the inorganic compound in the W/O type emulsion to produce the inorganic spherical body. In the process for forming the W/O type emulsion, the W/O type emulsion is formed by extruding out the aqueous liquid containing the inorganic compound into the organic liquid flowing with the flow rate of 0.001-2 m/s under a laminar flow through a flow channel, passing through a diaphragm with micro-pores. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an inorganic sphere capable of obtaining an inorganic sphere having an average particle size of 100 μm or larger.

  Conventionally, various methods have been studied as methods for obtaining inorganic spheres such as spherical silica. As a representative method, for example, a method in which silica sol is spheroidized with a spray dryer and dried (Patent Document 1), or a W / O type emulsion is prepared, and inorganic particles are contained in droplets of an aqueous solution of an inorganic compound in the emulsion. The method (patent document 2) of obtaining an inorganic spherical body by precipitating is mentioned. However, the method of spheroidizing the silica sol with a spray dryer has problems that the surface of the resulting spherical body is easily dented and it is difficult to obtain a true spherical shape, and that the particle size distribution width is too wide. . In any of the methods, if an inorganic spherical body having a large average particle diameter of 100 μm or more is to be produced, the particles are destroyed due to expansion and contraction in the skin and the center when solidified. In some cases, it was difficult to obtain a spherical body.

JP-A-61-171533 (Claims) Japanese Examined Patent Publication No. 57-55454 (Claims)

  An object of the present invention is to provide a method for producing an inorganic sphere having a large particle diameter of 100 μm or more in average particle diameter.

  The present invention includes a step of dispersing an aqueous liquid containing an inorganic compound in an organic liquid to form a W / O emulsion, a step of adding a metal alkoxide to the W / O emulsion, and the W / O emulsion. The manufacturing method of the inorganic spherical body which passes through the process of solidifying the aqueous liquid containing an inorganic compound in it, and producing | generating an inorganic spherical body.

  By the production method of the present invention, inorganic spheres having an average particle size of 100 to 1000 μm can be stably produced in the W / O emulsion method.

  In the present invention, an aqueous liquid containing an inorganic compound is dispersed in an organic liquid to form a W / O emulsion.

Any aqueous liquid containing an inorganic compound can be applied as long as it can form an inorganic sphere by solidification after forming a W / O emulsion, and the inorganic compound is dissolved or dispersed in the aqueous liquid. Any state may be used. As the inorganic compound, for example, colloidal silica, colloidal alumina, alkali silicate, and alkali aluminate are preferable. Regarding alkali silicate or alkali aluminate, examples of the alkali metal include lithium, sodium, and potassium. Among them, sodium is particularly preferable because it is easily available and inexpensive. As the inorganic compound, colloidal silica and alkali silicate are preferable, and alkali silicate is particularly preferable because it is easy to handle. As the alkali silicate, the molar ratio of SiO ₂ / M ₂ O (M is Na, K, Li) is preferably 2 to 3.8, particularly preferably 2 to 3.5. Moreover, as an aqueous liquid containing an inorganic compound, it is preferable that it is solid content concentration 5-45 mass%, it is especially preferable that it is solid content concentration 15-40 mass%, and solid content concentration is 20-35 mass%. Most preferred.

  The organic liquid is preferably a saturated hydrocarbon having 9 to 12 carbon atoms, and examples thereof include nonane, decane, undecane, and dodecane. These organic liquids preferably have good chemical stability, and may be linear hydrocarbons or hydrocarbons having side chains. In addition, these organic liquids comprehensively consider operability, safety to fire, separation between solid particles and organic liquid, shape characteristics of inorganic spherical particles, solubility of organic liquid in water, etc. Are preferably selected.

  The flash point of the organic liquid is preferably 20 to 80 ° C. If the flash point is less than 20 ° C, the flash point is too low, which is not preferable from the viewpoint of fire prevention and work environment. If the flash point is higher than 80 ° C, hydrocarbons to the inorganic spheres to be obtained are not preferable. This is not preferred because there is a risk of adhesion.

  The organic liquid preferably has a boiling point of 200 ° C. or lower in a state where the atmospheric pressure is 0.1 MPa. Thereby, when the inorganic spheres after solidification and the organic liquid are solid-liquid separated, the organic liquid adhering or adsorbing to the inorganic spheres after separation can be vaporized and separated by a drying operation or the like. Therefore, it is preferable. It is particularly preferable that the organic liquid has a boiling point of 180 ° C. or lower at a pressure of 0.1 MPa. The organic liquid is particularly preferably nonane or decane.

  In the present invention, it is preferable to add a surfactant to the organic liquid when forming the W / O emulsion. As the surfactant, an anionic surfactant or a cationic surfactant can be used, but a nonionic surfactant is particularly preferable in terms of easy adjustment of hydrophilicity and lipophilicity. Examples of nonionic surfactants include polyethylene glycol fatty acid esters, polyethylene glycol alkyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl ethers, and the like.

  The surfactant varies depending on conditions such as the type of surfactant, HLB (Hydrophile-lipophile balance) which is an index indicating the degree of hydrophilicity or hydrophobicity of the surfactant, and the particle size of the target inorganic sphere. It is preferable to contain 500 to 20000 ppm with respect to the organic liquid. If the content is less than 500 ppm, droplets of the aqueous liquid to be emulsified become large and the emulsion may become unstable, which is not preferable. If the content is more than 20000 ppm, it adheres to the resulting inorganic spheres. This is not preferable because the amount of the surfactant to be used may increase. The surfactant content is particularly preferably 1000 to 10,000 ppm.

  In the present invention, a conventionally known method can be used as a method for forming a W / O emulsion. For example, a method using various mixers, a homogenizer, a mill, or the like, or a partition wall having micropores is used. And the like. Among these, a method using partition walls having micropores is particularly preferable because inorganic spheres having a narrow particle size distribution can be obtained. A method of using a partition wall having micropores will be described in detail later.

  This method of forming a W / O type emulsion is preferable because emulsion particles having an average particle size of 100 to 1500 μm are obtained, and thereby inorganic spheres having an average particle size of 100 to 1000 μm are obtained. If the emulsion particles have an average particle size of less than 100 μm, the average particle size of the resulting inorganic spheres is less than 100 μm, which is not preferable. If the emulsion particles have an average particle size of more than 1500 μm, the resulting inorganic spheres have average particles. Since the diameter exceeds 1000 μm, it is not preferable. In the present specification, a method of observing the average particle size of the emulsion particles using an optical microscope is preferable, and a method of measuring the average particle size of the inorganic sphere by a laser scattering method is preferable. In the present specification, the average particle size of the inorganic spherical particles is based on volume.

  Next, in this invention, the process of adding a metal alkoxide to the obtained W / O type | mold emulsion is passed. As a result, in the W / O emulsion, the metal alkoxide is hydrolyzed on the surface of the droplet of the aqueous liquid containing the inorganic compound, and a metal oxide is generated in the outer shell portion, thereby maintaining the droplet in a spherical shape. It is preferable because it can be considered that cracking during solidification can be suppressed.

  As the metal alkoxide, silicon alkoxide or aluminum alkoxide is preferable. As silicon alkoxide, silicon tetramethoxide, silicon tetraethoxide, silicon tetrapropoxide, and silicon tetrabutoxide are preferable. As aluminum alkoxide, aluminum trimethoxide, aluminum triethoxide, aluminum tripropoxide, and aluminum tributoxide are preferable. preferable. Among them, tetramethoxylane and tetraethoxysilane are particularly preferable in the case of alkoxysilane, and aluminum trimethoxide and aluminum triethoxide are particularly preferable in the case of aluminum alkoxide because it is highly reactive and can form a skin instantly. .

  The amount of metal alkoxide added is preferably 0.05 to 5 times the mass of the inorganic compound in the aqueous liquid containing the inorganic compound. If the amount added is less than 0.05 times the mass, the amount of metal alkoxide is insufficient, so that it may not be possible to obtain inorganic spheres having a large average particle size, and the amount added is not preferred. If it is more than double mass, it is not preferable because the emulsion particles may aggregate. The addition amount of the metal alkoxide is particularly preferably 0.2 to 3 times mass. The metal alkoxide may be added all at once or may be added in several times. After adding the metal alkoxide to the W / O type emulsion, it is preferable to stir for 1 to 120 minutes. Moreover, it is preferable that the temperature at the time of stirring is 80 degrees C or less, and it is especially preferable that it is 5-45 degreeC.

  Next, in this invention, the process of solidifying the aqueous liquid containing the inorganic compound in W / O type | mold emulsion and producing | generating an inorganic spherical body is passed. Thereby, since the obtained inorganic spherical body precipitates in an organic liquid and can be collected, it is preferable. As solidifying agents, inorganic acids such as hydrochloric acid, carbonic acid, sulfuric acid, nitric acid and their ammonium salts, organic acids such as acetic acid, formic acid, propionic acid, isobutyric acid, butyric acid, oleic acid, trifluoroacetic acid, and their ammonium salts Can be used. In the case of colloidal silica or colloidal alumina, inorganic salts such as sodium chloride, potassium chloride, and calcium chloride can also be used. Among them, as the solidifying agent, carbonic acid is most preferable because of easy operation. As carbonic acid, pure carbon dioxide having a concentration of 100% may be used as it is, or carbon dioxide diluted with air or an inert gas may be used.

  When the inorganic compound is an alkali silicate or an alkali aluminate, the amount of the solidifying agent used is preferably 0.8 to 100 normal with respect to 1 mol of the alkali in the aqueous liquid containing the inorganic compound. In the case of colloidal silica or colloidal alumina, the mass is preferably 0.01 to 5 times the solid content in the aqueous liquid containing the inorganic compound. Further, the time required for solidification is preferably 4 to 30 minutes, and a temperature of 5 to 30 ° C is preferable.

  For example, when the inorganic compound is an alkali silicate, the droplet of the aqueous solution containing the alkali silicate is spherical by gelling the W / O emulsion with a solidifying agent such as an acid after the addition of the silicon alkoxide. It is preferable that it is gelled while maintaining a spherical silica hydrogel. After the completion of gelation, it is preferable that the reaction system is allowed to stand to separate the silica hydrogel by two-phase separation into an organic liquid phase and an aqueous phase containing silica hydrogel. For example, when a saturated hydrocarbon is used as the organic liquid, the organic liquid phase is separated in the upper layer and the aqueous phase containing silica hydrogel is separated in the lower layer. The aqueous phase containing the silica hydrogel can be separated from the organic liquid and obtained as a water slurry. An acid such as sulfuric acid is added to the obtained water slurry to adjust to pH 1 to 5 to complete the gelation of the silica hydrogel in the water slurry, at 60 to 150 ° C, preferably 80 to 120 ° C. After removing a few saturated hydrocarbons remaining in the water slurry by steam distillation, the silica hydrogel can be aged by adjusting the water slurry to about pH 7-9 and heating. preferable. It is preferable because fine pores can be formed in the silica hydrogel obtained by this aging. Thereafter, a spherical silica hydrogel can be obtained by filtering the water slurry.

  In addition, when a silica hydrogel is obtained, an alkali metal salt (for example, sodium silicate is used and sodium carbonate is generated if the solidifying agent is carbonic acid) is produced as a by-product in the silica hydrogel. In order to prevent it from remaining on the surface, it is preferable to sufficiently wash with water. The silica hydrogel washed with water is particularly preferably added with water again as a slurry to repeat filtration and washing with water. For washing with water, water-soluble alcohols such as methanol and ethanol may be used instead of water. In addition, when washing with water, an operation of adjusting the water slurry to about pH 1 to 5 as necessary and aging again may be performed as necessary. The obtained silica hydrogel is preferably dried at 10 to 150 ° C. for 1 to 30 hours because a porous spherical silica gel is obtained.

  The obtained spherical silica gel may be fired at 400 to 1200 ° C., preferably 700 to 1100 ° C. Thereby, it is possible to increase the bonding force of the gel and obtain a spherical silica gel with higher strength, which is preferable. Further, when the obtained spherical silica gel is baked, a solution in which an alkali metal, alkaline earth metal, transition metal, or salt thereof is dissolved and dispersed is appropriately immersed in the spherical silica gel by dipping or spraying. It may be added. This is preferable because the resulting spherical silica gel can be made non-porous and properties such as an expansion coefficient can be adjusted.

  In the present invention, the step of dispersing an aqueous liquid containing an inorganic compound in an organic liquid to form a W / O emulsion flows in the flow path at a flow rate of 0.001 to 2 m / s and in a laminar flow state. It is preferable to carry out by a method in which an aqueous liquid containing an inorganic compound is extruded into an organic liquid through a partition wall having micropores to form a W / O type emulsion. By this method, the aqueous liquid press-fitted from the micropores can grow larger than the pore diameter at the outlet of the micropores due to the interfacial tension, and then the aqueous liquid is separated by the flow of the organic liquid. Therefore, since the emulsion particles are formed in an organic liquid, emulsion particles having a uniform particle size are always obtained, which is preferable.

The flow rate of the organic liquid is preferably 0.001 to 2 m / s. As a result, the Reynolds number of the organic liquid flowing in the flow path can be made 2100 or less, the flow of the organic liquid becomes a laminar flow state, the flow of the organic liquid is stabilized, and the inorganic liquid supplied through the micropores is included. Since the aqueous liquid always becomes emulsion particles having a constant particle size, an inorganic sphere having a uniform particle size can be obtained, which is preferable. If the Reynolds number is more than 2100, the flow of the organic liquid becomes turbulent, so that the emulsion particles are not uniform in the particle size of the aqueous liquid as in the conventional case. As a result, the particle size of the inorganic sphere is also uneven. Therefore, it is not preferable. The Reynolds number of the organic liquid is particularly preferably 500 or less. The flow rate of the organic liquid is particularly preferably 0.01 to 1 m / s. In the present invention, the shape of the organic liquid channel is not particularly limited. For example, the Reynolds number when the cross section of the flow path is circular is calculated by Equation 1, and the inner diameter D of the flow path uses the minimum diameter in the cross section of the flow path. Here, D is the inner diameter (m) of the flow path, u is the average flow velocity (m / s), ρ is the fluid density (kg / m ³ ), and μ is the fluid viscosity (Pa · s).
Reynolds number (−) = D · u · ρ / μ Equation 1

In addition, the Reynolds number when the cross section of the flow path is triangular, rectangular, or the like and is not circular is calculated by Equation 2. Here, r is the flow path radius (m) = the cross-sectional area of the flow path (m ² ) / the circumferential length (m) in contact with the fluid of the cross-section of the flow path, and u, ρ, and μ are the same as in Equation 1. is there.
Reynolds number (−) = 4 × r · u · ρ / μ Equation 2

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the figure, 1 and 2 are acrylic resin plates, 3 is a stainless steel plate, and 4 is a partition. In FIG. 1, an aqueous liquid containing an inorganic compound is introduced from a nozzle 7, and pressed into an organic liquid flowing in a laminar flow state so as to be introduced from the nozzle 5 and discharged from the nozzle 6 through the micro holes 8. The aqueous liquid press-fitted from the micropore 8 grows larger than the pore diameter at the outlet of the micropore 8 due to the interfacial tension. Thereafter, the aqueous liquid is separated by the flow of the organic liquid, and becomes W / O type emulsion particles in the organic liquid.

  In the present invention, as a material constituting the partition wall, it is preferable to use a material having resistance to an aqueous liquid and an organic liquid containing an inorganic compound, and a material made of a metal or a resin is preferable. When the material of the partition wall is a metal, it is preferable because it is excellent in mechanical strength such as resistance to water and organic liquids and processability, wear resistance, and bending resistance. Specifically, nickel, a nickel alloy, A metal such as stainless steel is preferred. Among these, stainless steel is particularly preferable because it is relatively inexpensive and easily available, and has excellent resistance and workability. Further, when the partition wall material is a resin, it is preferable because of excellent workability and dimensional stability. Specifically, the partition wall is made of polyphenylene sulfide, polyether ether ketone, polyimide, polyamideimide, aromatic polyester, and fluororesin. It is preferably any one selected from the group.

  In the case where the partition walls are made of metal, it is preferable to perform water repellent treatment as necessary. Thereby, since the aqueous liquid containing an inorganic compound is easily cut as droplets, emulsion particles having a stable particle size distribution can be prepared, which is preferable. Specifically, the water repellent treatment is preferably performed by coating the surface using a water repellent treatment agent in which a hydrophobic resin or a silane coupling agent is dissolved in a solvent. As the hydrophobic resin, thermoplastic resins such as polymethyl methacrylate, polyethylene terephthalate, and polyvinyl acetate, and fluorine resins are preferable. The coating method can be carried out by any method, but the dip coating method is particularly preferred because it can be applied thinly and uniformly. Moreover, it is preferable that the film thickness at the time of water-repellent treatment is 0.001-5 micrometers. When the film thickness is less than 0.001 μm, the durability and mechanical strength of the water-repellent-treated film are insufficient, and it may be easily peeled off. In this case, the micropores of the partition walls 4 may be blocked, which is not preferable.

  The partition wall thickness is preferably 10 to 500 μm. When the partition wall thickness is less than 10 μm, the strength is weak and the sheet is bent or the flatness of the sheet is impaired, so the uniformity of the flow of the organic liquid near the partition wall surface is impaired, and uniform emulsion particles are formed. This is not preferable because it may not be possible. Further, if the partition wall thickness exceeds 500 μm, it is not preferable because it is difficult to process, and it takes time, and there is a possibility that the cost may increase and the processing accuracy may be deteriorated. It is particularly preferable that the partition wall has a thickness of 30 to 200 μm.

  As a method of forming micropores in the partition wall, it can be performed by a conventionally known method, and laser processing, etching processing, electroforming processing, press processing, and the like can be applied. A laser processing method using an excimer laser, a UV-YAG laser, or the like is particularly preferable.

  The micropores in the partition wall preferably have a circular cross-sectional shape, but may have a shape other than a circular shape. Any shape selected from the group consisting of a rectangle, an ellipse, and a triangle that is not convex on the inside is preferable because it is relatively easy to process and an inorganic sphere having a uniform particle diameter can be stably produced. . However, it is necessary that the hole of any shape has a diameter smaller than the channel width of the organic liquid.

  Here, when the cross-section of the micropore is a shape other than a circular shape, the droplet has a curvature distribution when it becomes a droplet at the exit of the hole, and is spontaneously separated relatively early in the organic liquid. Presumed to be emulsion particles. Therefore, compared to the case where circular holes are used, a product having a relatively small emulsion particle size tends to be obtained. In addition, when the cross section of the micropore has a shape other than a circular shape, the ratio of the diameter of the circle circumscribing the cross-sectional shape to the diameter of the circle inscribed in the cross-sectional shape is preferably 20 or less. When the diameter ratio is more than 20, it is not preferable because when the emulsion particle size is generated in the organic liquid, the droplets may be divided in the major axis direction and the emulsion particles may become non-uniform. The diameter ratio is particularly preferably 10 or less. Most preferably, the diameter of the circle inscribed in the cross-sectional shape is 1 μm or more, and the diameter of the circle inscribed in the cross-sectional shape is 80 μm or less.

Moreover, it is preferable that it is 10-2000 micrometers, and it is especially preferable that it is 20-1000 micrometers as the 4 times value of the dynamic radius r of the cross section of a micropore. If the 4-fold value of the dynamic radius r of the cross-section of the micropore is less than 10 μm, the supply amount of the aqueous liquid containing the inorganic compound becomes small, which is not preferable in terms of productivity. If it exceeds 2000 μm, emulsion particles that deviate from the intended particle diameter are likely to be formed, which is not preferable. Here, the hydrodynamic radius r of the cross section of the micropore is the hydrodynamic radius r (m) of the cross section = the cross sectional area of the micropore (m ² ) / the perimeter of the micropore cross section (m ). Therefore, when the cross section of the microhole is circular, the hydrodynamic radius r = the inner diameter D / 4 of the circle, and therefore, the quadruple value of the hydrodynamic radius r corresponds to the inner diameter D of the circle.

In the present invention, it is preferable to provide a plurality of micropores 8 for supplying an aqueous liquid containing an inorganic compound from the viewpoint of productivity. The number of micropores is preferably 100 or more, particularly preferably 1000 or more, per unit area of 0.01 m ² .

  In addition, the arrangement of the micropores 8 at that time is not particularly limited, but from the viewpoint of productivity and workability, the width direction of the partition wall 4 (width direction of the organic liquid channel) and the length direction (organic) A parallel arrangement in which a plurality of micropores are installed at a constant pitch in each of the flow directions of the liquid flow path, or two micropores adjacent in the width direction among the microarrays arranged in parallel, adjacent in the length direction It is preferable that the two micropores are selected and a staggered arrangement in which another microhole is installed at the center of a rectangular diagonal line formed by connecting the centers of these holes. Among these, the staggered arrangement is particularly preferable from the viewpoint of improving productivity because the minute holes can be arranged densely and the open area ratio can be increased.

  Moreover, it is preferable that the aperture ratio of the partition 4 is 1-35%. If the open area ratio is less than 1%, the productivity of the resulting inorganic spheres is lowered and the cost is increased, which is not preferable. Further, when the open area ratio is more than 35%, droplets of the aqueous liquid formed by press-fitting the aqueous liquid from the respective micropores are united, and as a result, the particle diameter of the obtained emulsion particles becomes non-uniform. This is not preferable because of fear. The porosity is particularly preferably 2 to 25%.

Note that the hole area ratio when a plurality of micropores having a constant area are arranged in a fixed arrangement is calculated by Equation 3. At this time, S is the cross-sectional area (m ² ) of the micropores, P ₁ is the pitch (m) in the width direction, and P ₂ is the pitch (m) in the length direction.
Opening ratio (%) = 100 × S / (P ₁ × P ₂ ) Equation 3

Further, in Expression 3, the opening ratio when circular micro holes are installed in a parallel arrangement can be calculated by Expression 4. Here, D is the micropore diameter (m), and P ₁ and P ₂ are the same as in Equation 3.
Opening ratio (%) = 78.5 × D ² / (P ₁ × P ₂ ) (4)

In addition, in Formula 3, when circular micropores are installed in a staggered arrangement, the aperture ratio when the angle formed by the two diagonal lines defined above is 90 ° (square staggered arrangement) can be calculated by Formula 5. In addition, the aperture ratio in the case of 60 ° (60 ° staggered arrangement) can be calculated by Equation 6. Here, D is the same as Equation 4, and P is the pitch (m). Note that P in Expression 6 indicates the shorter one (m) of the pitches in the width direction and the length direction.
Opening ratio (%) = 157 × D ² / P ² Formula 5
Opening ratio (%) = 91 × D ² / P ² Formula 6

  The microholes 8 are preferably installed on the partition wall 4 with a space of 1/2 or more of the diameter of the circle circumscribing the cross-sectional shape of the microholes, and further, the circle circumscribing the cross-sectional shape of the microholes. It is particularly preferable to install with an interval equal to or greater than the diameter of the above. If it is installed at intervals shorter than ½ of the diameter of the circumscribed circle, the emulsion droplets that are generated are likely to coalesce, and as a result, the particle size of the emulsion may become non-uniform, which is not preferable.

  Furthermore, from the viewpoint of efficiently obtaining an inorganic sphere having a target particle diameter, in the present invention, the ratio of the average particle diameter of the inorganic sphere to the four times the hydrodynamic radius r of the cross section of the micropore is 0.1. It is preferable to set it to ~ 5. When the ratio of the average particle diameter of the inorganic spheres to the value of four times the hydrodynamic radius r is less than 0.1, the productivity of the resulting inorganic spheres decreases, and the average particle diameter of the inorganic spheres is less than the target value. This is not preferable because it may increase, and a ratio of more than 5 is not preferable because it may be difficult to control the particle diameter of the resulting inorganic spherical body. It is particularly preferable that the ratio of the average particle diameter of the inorganic spheres to a value that is four times the dynamic water radius r is 0.3 to 3.

  In addition, you may install the manufacturing apparatus of the inorganic spherical body of this invention so that the partition 4 may become parallel with respect to a horizontal surface like FIG. However, when the density of the organic liquid is smaller than the density of the aqueous liquid, the organic liquid flow path is installed so as to have an angle of 30 ° or more with respect to the horizontal plane, and the organic liquid is flowed upward from below. Inorganic spheres having a uniform particle diameter can be easily obtained, which is preferable. It is particularly preferable that the partition wall 4 be installed so as to be perpendicular to the horizontal plane. On the other hand, when the density of the organic liquid is larger than the density of the aqueous liquid, it is preferable to flow the organic liquid downward from the upper side because the above particle diameter can be made uniform.

  When the partition 4 is installed so as to have an angle of 30 ° or more with respect to the horizontal plane, a pressure due to the liquid depth is applied to each of the aqueous liquid side and the organic liquid side on the predetermined horizontal plane in the height direction. Assuming that the liquid depths of the aqueous liquid and the organic liquid are substantially the same in a specific horizontal plane, a pressure corresponding to (aqueous liquid density−organic liquid density) × liquid depth is applied due to the density difference between the aqueous liquid and the organic liquid. . Therefore, when the density of the organic liquid is smaller than the density of the aqueous liquid, the organic liquid is flowed from the bottom to the top. In comparison, the change in the pressure difference between the aqueous liquid side and the organic liquid side in all the channels can be relatively narrow, which is preferable. Thereby, the supply amount of the aqueous liquid from each micropore on the partition wall 4 can be stabilized, and the particle size of the obtained emulsion particles can be made uniform. Therefore, the particle size of the obtained inorganic spheres can be made uniform. This is preferable.

  In addition, the particle size of the emulsion particles to be generated is influenced not only by the installation conditions of the micropores defined above, but also by the ratio of the flow velocity in the flow direction of the organic liquid to the flow velocity in the flow direction of the aqueous liquid. Here, in FIG. 1, the flow velocity in the flow direction of the aqueous liquid may be measured at the micropore 8 portion. The ratio of the flow rates is preferably 1 to 500. If the flow rate ratio is less than 1, it is difficult to separate the droplets due to the flow of the organic liquid and the emulsion particles may become non-uniform. Since there is a possibility of excessive consumption, it is not preferable from an economical viewpoint. The flow rate ratio is particularly preferably 10 to 300.

[Example 1]
(1) (Preparation of solution)
A sodium silicate aqueous solution having a SiO ₂ / Na ₂ O molar ratio of 3.09 (solid content concentration 28.88 mass%, density 1320 kg / m ³ ) was prepared. As the organic liquid, isononane (C ₉ H ₂₀ , density 730 kg / m ³ ) was used, and a solution in which 7000 ppm of sorbitan monooleate was dissolved in advance as a nonionic surfactant was prepared.

(2) (Emulsification device production)
The emulsifying device is as shown in the sectional view of FIG. First, two through holes with an inner diameter of 3.2 mm are formed in an acrylic plate 1 having a thickness of 20 mm, a length of 130 mm, and a width of 50 mm, and an outer diameter of 3.2 mm rubber tube piping (product name: die) Gontube R-3603) is connected to nozzles 5 and 6, respectively, so that liquid can be supplied from nozzle 5 and liquid can be discharged from nozzle 6. Another 20 mm thick, 130 mm long, 50 mm square acrylic plate 2 is formed with a 70 mm long, 3 mm wide groove and 3 mm inner diameter through hole, and a 1 mm inner diameter Teflon (registered) via joint parts. (Trademark) tube piping was connected, and it was set as the nozzle 7 so that the liquid could be supplied from the nozzle 7. A stainless steel plate having a thickness of 400 μm, a length of 120 mm, and a width of 50 mm was prepared, and a slit steel plate 3 provided with a slit having a length of 70 mm and a width of 3 mm at the center was prepared. Next, in the central part of the stainless steel plate 4 having a thickness of 50 μm, a length of 120 mm, and a width of 50 mm, eight through-holes having an inner diameter of 70 μm and a circular cross-sectional shape are formed by a UV-YAG laser at a pitch of 300 μm in the width direction. After piercing a total of 1328 as a parallel arrangement of 166 pieces at a pitch of 300 μm in the length direction, a solvent-soluble fluororesin (made by Asahi Glass, trade name: Cytop) is used as a solvent (made by Asahi Glass, trade name: CT-Solv100). The partition wall 4 was prepared by using the solution dissolved in (1) and coating by dip coating so that the thickness after drying was 0.1 μm. In the range surrounded by the line connecting the centers of the through holes provided at the outermost portions in the width direction and the length direction, the opening ratio of the partition walls 4 calculated from Equation 4 was 6.1%.

  The acrylic plate 1, the stainless steel plate 3, the partition wall 4, and the acrylic plate 2 were laminated in order and fixed with a clamp. At this time, the width direction and the longitudinal direction of the through hole made in the partition wall 4 are respectively aligned with the width and length direction of the slit made in the stainless steel plate 3 so that the area of the through hole is located at the center of the slit. In addition, the nozzle 5 and the nozzle 6 formed on the acrylic plate 1 were installed so that the holes of the nozzle 5 and the nozzle 6 were positioned on the slit formed in the stainless steel plate 3. The prepared emulsifier was supplied with water in advance and confirmed that the liquid did not leak.

(3) (Emulsification)
The emulsifying device prepared in (2) is used in a vertical position, and isononane in which the surfactant adjusted in (1) is dissolved is supplied from the nozzle 5 to the sodium silicate aqueous solution adjusted in (1) from the nozzle 7. Thus, a W / O type emulsion in which an aqueous sodium silicate solution was dispersed in isononane in which a surfactant was dissolved was continuously prepared. At this time, the supply amount of isononane in which the surfactant was dissolved was 1350 mL / h. Manufacture was performed at room temperature.

At this time, the Reynolds number of the flow of isononane was about 213 when calculated from the hydrodynamic radius of the flow path: 176.5 μm, the flow velocity: 0.31 m / s, and the viscosity: 7.5 × 10 ⁻⁴ Pa · s. It was in a laminar flow state. The supply amount of the sodium silicate aqueous solution was 76 mL / h, and the flow velocity in the flow direction in the micropores 8 was 0.55 × 10 ⁻³ m / s.

  The ratio of the flow rate in the flow direction of isononane to the flow rate in the flow direction in the micropore 8 portion of the sodium silicate aqueous solution supplied from the micropore 8 was 159. When the state of emulsification was continuously confirmed using a high-speed camera (not shown) installed in front of the acrylic resin plate 1, the aqueous sodium silicate solution was formed into droplets at the outlets of the micropores 8 and optically. When the state of emulsification was confirmed using a microscope, the emulsion particles had a substantially uniform particle size of about 300 μm.

(4) (Addition of silicon tetraethoxide)
Put the W / O type emulsion prepared in (3) into a 1000 mL capacity container, add 1.7 times the mass of silicon tetraethoxide to the sodium silicate in the emulsion while stirring at 15 ° C, Stir for 30 minutes.

(5) (Gelification)
Then, when carbon dioxide was blown into the emulsion at a supply rate of 100 mL / min for 30 minutes, silica hydrogel was produced. The resulting silica hydrogel water slurry was phase-separated from isononane by a specific gravity difference, and then the silica hydrogel water slurry was adjusted to pH 2 by adding a 20 mass% sulfuric acid aqueous solution to promote the gelation of the silica hydrogel. A 1% by mass aqueous sodium hydroxide solution was added to adjust the pH to 6.5, and the mixture was heated to 55 ° C. to age the silica hydrogel for 1 hour. Thereafter, the water slurry was allowed to cool to room temperature, and further 20 mass% sulfuric acid aqueous solution was added to adjust the pH to 1, and the mixture was allowed to stand for 3 hours to complete the aging of the silica hydrogel. Subsequently, the water slurry was filtered, and the resulting silica hydrogel was washed with water, dried at 120 ° C. for 20 hours, and then fired at 1000 ° C. for 30 minutes using a muffle furnace to obtain spherical silica gel.

(6) (Shape confirmation)
The obtained spherical silica gel was confirmed to be almost spherical from an optical microscope and a scanning micrograph. Moreover, when the particle size distribution was measured with a laser scattering device (MICROTRAC HRA9320-X100, manufactured by Honeywell), the average particle size was 195 μm, and the standard deviation was 33.9 μm. The value obtained by dividing the standard deviation of the particle size distribution by the number average particle size was 0.17, and it was confirmed that the silica gel had a substantially uniform particle size.

[Example 2 (comparative example)]
When the operation was performed in the same manner as in Example 1 except that silicon tetraethoxide was not added, it was not possible to maintain a spherical shape when gelled by adding carbon dioxide gas. No spherical silica gel was obtained, and crushed silica particles were obtained.

  The inorganic sphere obtained by the production method of the present invention is most suitable for a liquid chromatographic filler, a catalyst carrier, a spacer and the like.

The figure which shows sectional drawing of the emulsification apparatus used in Example 1

Explanation of symbols

1, 2: Acrylic resin plate 3: Stainless steel plate 4: Partition walls 5, 6, 7: Nozzle 8: Through hole

Claims (7)

  Dispersing an aqueous liquid containing an inorganic compound in an organic liquid to form a W / O emulsion, adding a metal alkoxide to the W / O emulsion, and the inorganic compound in the W / O emulsion The manufacturing method of the inorganic spherical body which solidifies the aqueous liquid containing this, and produces | generates an inorganic spherical body.   The step of dispersing the aqueous liquid containing the inorganic compound in the organic liquid to form a W / O type emulsion in the organic liquid flowing in a laminar flow state at a flow rate of 0.001 to 2 m / s in the flow path The method for producing an inorganic sphere according to claim 1, which is a step of forming a W / O emulsion by extruding an aqueous liquid containing an inorganic compound through a partition wall having micropores.   The method for producing an inorganic sphere according to claim 2, wherein a value four times the hydrodynamic radius r of the cross section of the micropore in the partition wall having the micropore is 10 to 2000 µm.   The method for producing an inorganic sphere according to claim 1, wherein the inorganic sphere has an average particle size of 100 to 1000 μm.   The said inorganic compound is an alkali silicate, The manufacturing method of the inorganic spherical body in any one of Claims 1-4.   The manufacturing method of the inorganic spherical body in any one of Claims 1-5 which uses an acid for solidification of the aqueous liquid containing the inorganic compound in the said W / O type | mold emulsion. The method for producing an inorganic sphere according to claim 6, wherein the acid is carbon dioxide.

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