JP6210070B2 - Method for producing spherical particles - Google Patents

Description

  The present invention relates to a method for producing spherical particles.

  Spherical particles have various particle diameters, pore structures, and surface characteristics. For example, toner particles, heat insulating materials, food additives, medical diagnostic agents, paint fillers, cosmetic fillers, resin film fillers, and liquid crystal It can be widely used for spacers, chromatographic fillers, catalysts, catalyst carriers, resin fillers, adsorbents, desiccants and the like.

  Examples of the spherical particles include spherical particles such as inorganic compounds such as silica and alumina, organic compounds such as polystyrene and polymethyl methacrylate, and mixtures of these inorganic compounds and organic compounds. Various methods have been proposed for producing these spherical particles.

  In Patent Document 1, in the method for producing inorganic microspheres, an aqueous solution containing an inorganic compound serving as a dispersed phase is pressed into an organic solvent through a microporous membrane to produce a W / O type suspension. A method for producing inorganic microspheres by adding a specific compound before or after preparing an O-type suspension is disclosed.

  In Patent Document 2, a plurality of micropores are formed in a water-repellent treated metal sheet, and an aqueous liquid containing an inorganic compound flows through the micropores in a laminar flow state at a flow rate of 0.001 to 2 m / s. A method for producing an inorganic sphere by extruding into an organic liquid to form a W / O emulsion and solidifying an aqueous liquid containing the inorganic compound in the W / O emulsion is disclosed.

Japanese Patent No. 2555475 JP 2011-26196 A

  In the method of Patent Document 1, since it is difficult to control the flow of the organic solvent in the preparation of the W / O type suspension, the droplet diameter distribution of the suspension is widened, and inorganic microspheres having a uniform particle diameter can be obtained. difficult.

In the method of Patent Document 2, an inorganic sphere having a uniform particle size can be produced. However, when the flow rate of the aqueous liquid, which is an inorganic compound that is a dispersed phase, is increased, the droplet size of the emulsion becomes non-uniform. As a result, it is difficult to increase productivity. In Example 1 of Patent Document 2, the flow rate of the dispersed phase per unit area of the micropore formation region calculated from the experimental data is 0.51 m ³ / m ² · hr, and it is desired to further increase the productivity.

  One object of the present invention is to obtain spherical particles having a uniform particle diameter with high productivity.

  As one aspect of the present invention, a dispersion containing a spherical particle precursor is passed through a micropore formed in the partition into a continuous phase liquid flowing at a flow rate of 0.3 to 10 m / s in a flow path partitioned by the partition. A step of extruding a phase liquid at a flow rate of 0.1 to 5 m / s per hole to produce an emulsion, a step of solidifying emulsion droplets containing the spherical particle precursor to form spherical particles, and the spherical particles It is a manufacturing method of spherical particles including the process of collect | recovering.

  As another aspect of the present invention, the dispersed phase liquid containing the spherical particle precursor is added to the continuous phase liquid flowing in the flow path partitioned by the partition walls through the micropores formed in the partition walls. A method for producing spherical particles in which an emulsion is produced by extruding at a flow rate of ˜5 m / s, and emulsion droplets containing the spherical particle precursor are solidified to form spherical particles, and the spherical particles are recovered. It is a manufacturing method of a spherical particle whose Reynolds number of the continuous phase liquid which flows in a path | route is 500-10000.

  According to the present invention, spherical particles having a uniform particle diameter can be obtained with high productivity.

FIG. 1 is a schematic cross-sectional view showing an example of an emulsifying apparatus according to an embodiment of the present invention. FIG. 2 shows a cross-sectional shape of a donut-shaped channel. FIG. 3 is a schematic view of a test facility for circulating the continuous phase in Example 11.

  Hereinafter, although the embodiment concerning the present invention is described, the illustration in this embodiment does not limit the present invention.

  As a method for producing spherical particles according to an embodiment of the present invention, a spherical liquid is formed by passing through a micropore formed in a partition wall into a continuous phase liquid flowing at a flow rate of 0.3 to 10 m / s in a flow path partitioned by the partition walls. A step of extruding a dispersed phase liquid containing a particle precursor at a flow rate of 0.1 to 5 m / s per hole to produce an emulsion, and a step of solidifying emulsion droplets containing a spherical particle precursor to form spherical particles And a step of collecting spherical particles.

  According to this, spherical particles with a uniform particle diameter can be obtained with high productivity.

Conventionally, in membrane emulsification, as disclosed in Patent Document 2, the Reynolds number is small (document value = about 213), and the flow velocity per hole of the dispersed phase liquid is slow (document value = 2 × 10 ^−3). It is known that uniform spherical particles can be obtained only under the condition m / s). However, in the present invention, it has been found that spherical particles having a uniform particle diameter can be obtained with high productivity even under a high Reynolds number condition by supplying both a dispersed phase liquid and a continuous phase liquid at a high flow rate.

  In the produced emulsion, the continuous phase liquid flowing in the flow path partitioned by the partition walls becomes the continuous phase, and the dispersed phase liquid extruded through the micropores becomes the dispersed phase. In the present embodiment, the continuous phase and the dispersed phase of the emulsion are low in compatibility with each other, and an emulsion may be prepared. In any form of a W / O (water-in-oil) emulsion and an O / W (oil-in-water) emulsion. There may be. When using an organic liquid as the continuous phase liquid and an aqueous liquid as the dispersed phase liquid, a W / O emulsion can be obtained. When using an aqueous liquid as the continuous phase liquid and an organic liquid as the dispersed phase liquid, an O / W emulsion can be obtained. Can be obtained.

  The volume ratio of the dispersed phase liquid and the continuous phase liquid at room temperature (20 to 23 ° C.) is, for example, 1 to 100, more preferably 1 to 10, as the volume ratio of the continuous phase / dispersed phase in the obtained emulsion. More preferably, it is 1-5.

(Continuous phase liquid and dispersed phase liquid)
"W / O emulsion"
As a continuous phase liquid for preparing a W / O emulsion, an organic liquid having low solubility, preferably insoluble in a dispersed phase liquid can be used. Examples of the organic liquid include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ethers, esters, fluorine-containing compounds and the like.

  Specific examples of the organic liquid include aliphatic hydrocarbons such as saturated hydrocarbons having 9 to 12 carbon atoms, n-hexane, isohexane, n-heptane, isoheptane, n-octene, and isooctene shown below; cyclopentane Cyclohexane, cyclohexene, and other alicyclic hydrocarbons; benzene, toluene, xylene, ethylbenzene, propylbenzene, cumene, mesitylene, tetralin, styrene, and other aromatic hydrocarbons; propyl ether, isopropyl ether, and other ethers; acetic acid Ethyl, n-propyl acetate, isopropyl acetate, n-butyl acetate, isoptyl acetate, n-amyl acetate, isoamyl acetate, butyl lactate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, Esters such as butyl butyrate; 1, , It can be exemplified fluorine-containing compounds such as 2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether. These may be used alone or in combination.

  As the organic liquid, saturated hydrocarbons having 9 to 12 carbon atoms are preferable, and comprehensive operations such as operability, safety to fire, separation between solidified particles and organic liquid, solubility of organic liquid in water, etc. Selected in consideration of The saturated hydrocarbon having 9 to 12 carbon atoms may be used alone, or two or more of them may be mixed and used. In addition, the saturated hydrocarbon having 9 to 12 carbon atoms may be a linear hydrocarbon or a hydrocarbon having a side chain as long as its chemical stability is good.

  Examples of the saturated straight chain hydrocarbon having 9 to 12 carbon atoms include n-nonane, n-decane, n-undecane, and n-dodecane. The saturated branched chain hydrocarbon having 9 to 12 carbon atoms includes isononane. , Isodecane, isoundecane, isododecane and the like.

  The flash point of the organic liquid is preferably 20 to 80 ° C, more preferably 30 to 60 ° C. Moreover, a nonflammable or a flame-retardant organic liquid can be used preferably.

  When a saturated hydrocarbon having a flash point of less than 20 ° C. is used as an organic liquid, since the flash point is too low, measures for fire prevention and work environment are required. When the flash point of the organic liquid is 20 ° C. or higher, the work environment can be improved by improving the fire resistance. On the other hand, when the temperature is 80 ° C. or lower, sufficient volatility can be obtained, and when the spherical particles are recovered from the organic liquid, the organic liquid can be prevented from adhering to and mixed into the spherical particles.

  The organic liquid having such a flash point is more preferably selected from saturated hydrocarbons having 9 to 12 carbon atoms.

  In the present embodiment, an emulsion is prepared from a continuous phase liquid and a dispersed phase liquid, and emulsion droplets are solidified to form spherical particles, and then the spherical particles and the continuous phase liquid are usually separated into solid and liquid. When the continuous phase liquid adheres to or adsorbs on the spherical particles after separation, it is preferable to separate them by filtration operation, washing operation, drying operation or the like.

  A surfactant may be added as an emulsifier to the continuous phase liquid. As the surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be used.

  Examples of the anionic surfactant include fatty acid sodium, alkyl sulfate, alkyl benzene sulfonate, and alkyl phosphate.

  Examples of the cationic surfactant include alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt and the like.

  Examples of amphoteric surfactants include alkyl dimethylamine oxide and alkyl carboxybetaine.

  Nonionic surfactants include, for example, polyethylene glycol fatty acid esters, polypropylene 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. Can be mentioned.

  These surfactants can be used alone or in combination of two or more.

  The amount of the surfactant used depends on conditions such as the type of the 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 spherical particles. Although it is different, it is preferable to make it contain in 0.01-2 mass% in the said continuous phase liquid, Preferably it is 0.1-0.5 mass%.

  By being 0.01 mass% or more, it can emulsify uniformly and an emulsion can be stabilized more. On the other hand, when the content is 2% by mass or less, it is possible to prevent the surfactant from adhering to and mixing with the spherical particles as the final product. When the viscosity of the dispersed phase liquid is low, a lower surfactant concentration is preferable in order to uniformly emulsify.

  In the present embodiment, since the flow rate of the continuous phase liquid is high, the action of shearing the flow of the continuous phase liquid causes the dispersed phase liquid to be separated at the outlet side of the micropores and become an emulsion droplet more strongly. be able to. The effect of this shearing force works together with the emulsification by the action of the surfactant, so that the dependency of the surfactant in the formation of emulsion droplets decreases. That is, when the flow rate conditions of the disperse phase liquid and the continuous phase liquid are the same, the particle diameter of the produced spherical particles is hardly affected by the concentration of the surfactant, and the particle diameter of the spherical particles (for example, the average particle diameter D50) is further increased. Can be constant.

  In addition, since the particle size of the spherical particles can be made more constant without being affected by the concentration of the surfactant, the particle size of the spherical particles can be used even if the continuous phase liquid is recycled and used. Can be kept more constant.

  On the other hand, when the flow rate of the continuous phase liquid is low, the effect of shearing force is small, and the progress of emulsification depends on the action of the surfactant, and the particle size of the spherical particles may vary depending on the concentration of the surfactant. . In this case, when the continuous phase liquid is recycled and used, the action of the surfactant may be reduced in the system, whereby the particle size of the spherical particles increases according to the number of circulations, and the particle size distribution. May spread.

  You may add other arbitrary components, such as a thickener, to a continuous phase liquid. Examples of the thickener include lipophilic scumite and liquid paraffin. A thickener can be mix | blended with 0.1-10 mass% with respect to the whole continuous phase liquid.

  As the dispersed phase liquid in preparing the W / O emulsion, an aqueous liquid having low solubility, preferably insoluble, in the continuous phase liquid can be used, and the precipitate of the spherical particle precursor is obtained by solidification. It is preferable that the liquid is an aqueous liquid capable of forming. The main component of the aqueous liquid can be water, and a water-soluble organic liquid may optionally be included.

  The spherical particle precursor contained in the dispersed phase liquid may be either an inorganic compound or an organic compound, or a hybrid of both. By using two or more inorganic compounds and / or organic compounds as the spherical particle precursor, spherical particles of the composite material can be obtained.

  Specifically, as an aqueous liquid containing an inorganic compound, an alkali metal (mainly lithium, sodium, potassium, rubidium) silicate or aluminate; an oxide of silicon, aluminum, titanium, zinc, cerium or tin ; Halides of alkaline earth metals (mainly calcium, strontium, barium); copper oxides, sulfates, hydrochlorides and nitrates; including oxides of iron, cobalt or nickel, sulfates, hydrochlorides and nitrates, etc. Mention may be made of aqueous liquids. These may be used alone or in combination.

  Further, a colloidal solution such as silica sol or alumina sol can be used.

  Examples of the organic compound include polyvinyl alcohol, chitosan, chitin and the like. These may be used alone or in combination.

  In the present embodiment, it is preferable to use an aqueous liquid containing at least one selected from the group consisting of potassium silicate, sodium silicate, sodium aluminate and silica as the dispersed phase liquid containing the spherical particle precursor.

  Specifically, an aqueous solution in which water-soluble silica is dissolved, an aqueous dispersion (colloidal silica) in which solid silica is dispersed, such as silica sol obtained by hydrolyzing an organosilicon compound and commercially available silica sol, potassium silicate, Examples thereof include an aqueous solution of sodium silicate.

  Of these, sodium silicate is particularly preferred because of its availability and economic reasons. The ratio of sodium and silicic acid is preferably 2.0 to 3.8 in terms of SiO2 / Na2O (molar ratio), more preferably 2.0 to 3.5. Further, the concentration of alkali silicate or silica in the aqueous liquid is preferably 1 to 30% by mass, more preferably 5 to 25% by mass as the SiO 2 concentration.

"O / W emulsion"
As the continuous phase liquid for producing the O / W emulsion, an aqueous liquid having low solubility, preferably insoluble in the dispersed phase liquid can be used. The main component of the aqueous liquid can be water, and a water-soluble organic liquid may optionally be included.

  When an aqueous liquid is used as the continuous phase liquid, optional components such as a surfactant and a thickener can be appropriately added. As the surfactant, those common to the above-described W / O emulsion can be used. Examples of the thickener include cellulose, ethyl cellulose, gum arabic and the like. The compounding quantity of surfactant and a thickener is common in the case of the above-mentioned W / O emulsion.

  As the dispersed phase liquid in preparing the O / W emulsion, an organic liquid having low solubility, preferably insoluble, in the continuous phase liquid can be used, and the precipitate of the spherical particle precursor is obtained by solidification. It is preferable that the liquid is an organic liquid capable of forming.

  As an example of the dispersed phase liquid of the O / W emulsion, there is one that contains a polymerizable monomer as a spherical particle precursor, which is polymerized by solidification to produce spherical resin particles. The polymerizable monomer may be blended as a main component in the dispersed phase liquid to constitute an organic liquid. Moreover, you may mix | blend the dilution solvent which does not have polymericity arbitrarily. Specific examples of such a polymerizable monomer include tetraethoxysilane, siloxane oligomer, aluminum isopropoxide, acrylic acid ester, methacrylic acid ester, styrene, vinyl acetate, and vinyl chloride. Examples of the siloxane oligomer include hydrolysates such as tetramethoxysilane, tetraethoxysilane, and tetraphenoxysilane.

  When a polymerizable monomer is used for the dispersed phase liquid, a reaction catalyst or a polymerization initiator may be previously contained in the dispersed phase liquid, or may be added later. Specifically, known polymerization initiators for radical polymerization such as one or two or more acid catalysts, base catalysts, peroxide polymerization initiators, and azo polymerization initiators can be used. Specifically, hydrochloric acid, nitric acid, etc. as the acid catalyst, sodium hydroxide, ammonia, etc. as the base catalyst, benzoyl peroxide, methyl ethyl ketone peroxide, etc. as the peroxide polymerization initiator, Examples include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), and the like.

(Emulsion preparation process)
In this embodiment, an emulsion is prepared by extruding a dispersed phase liquid containing a spherical particle precursor through a micropore formed in a partition wall into a continuous phase liquid flowing in a flow path partitioned by partition walls. As a result, it is possible to produce a droplet containing spherical particle precursors in a continuous phase, that is, an emulsion in which emulsion droplets are in a dispersed phase.

  The shape of the flow path partitioned by the partition wall through which the continuous phase liquid flows is not particularly limited. For example, the cross-sectional shape of the flow channel orthogonal to the flow direction of the continuous phase liquid (hereinafter sometimes simply referred to as “the cross-sectional shape of the flow channel”) is a circle, an ellipse, a donut shape, a rectangle, a triangle, a polygon, etc. It may be, but is preferably rectangular.

  FIG. 2 shows a cross-sectional shape of the donut-shaped channel. In the donut-shaped channel 30a, the outer cylindrical partition wall 30 and the inner cylindrical partition wall 40 form a continuous phase liquid channel 30a. A microscopic hole 40 a is formed over the entire circumference of the inner cylindrical partition wall 40. A plurality of the micro hole portions 40a may be formed in the axial direction of the inner cylindrical partition wall. The dispersed phase liquid is supplied into the inner cylindrical partition wall 40 and pushed out from the micropore 40a to the flow path 30a.

  Although one channel may be defined by the partition walls, it is preferable to provide a plurality of channels in order to obtain high productivity.

  The partition that divides the flow path is a member that separates the continuous phase liquid and the dispersed phase liquid, and is a plate-like or membrane-like member that has micropores penetrating in the thickness direction of the partition. As the material of the partition wall, a material having resistance to the dispersed phase liquid and the continuous phase liquid is preferable. Examples thereof include inorganic materials such as glass and ceramics, metal materials such as nickel and nickel alloys, stainless steel, and resin materials such as polyphenylene sulfide, polyether ether ketone, polyimide, polyamideimide, acrylic, and polyethylene terephthalate. Among them, it is preferable to use a stainless steel sheet because it is relatively inexpensive and easily available, and has excellent resistance and workability.

  The overall shape of the minute hole is not particularly limited, and may be, for example, a flat plate, a disk, a cylinder, a square tube, or the like. The cross-sectional shape of the micropores orthogonal to the flow direction of the dispersed phase liquid (hereinafter sometimes simply referred to as “the cross-sectional shape of the micropores”) is not particularly limited, and for example, a circle, an ellipse, a rectangle, a triangle It may be a polygon or the like. Although not limited to this, the length in the short direction of the cross-sectional shape of the outlet portion of the micropores, that is, the flow path side of the continuous phase can be set to, for example, 0.1 to 100 μm. It can be set to 1 to 100 μm.

  One or a plurality of micropores can be provided in the partition wall. When there are a plurality of channels, one or a plurality of micropores can be provided for each channel.

In this embodiment, by setting the flow rate of the continuous phase liquid flowing in the flow path partitioned by the partition wall to 0.3 to 10 m / s, emulsion droplets having a narrow particle size distribution can be obtained and solidified into spherical shapes. The particle size distribution of the particles can also be narrowed. The flow rate of the continuous phase liquid is preferably 1.0 m / s or more, more preferably 2.0 m / s or more, and preferably 9.0 m / s or less, more preferably 8.0 m. / S or less. Here, the flow rate of the continuous phase liquid is a value obtained by dividing the flow rate (m ³ / s) of the continuous phase liquid flowing in the flow path partitioned by the partition per unit time by the cross-sectional area (m ² ) of the flow path. That is.

  The height of the flow path partitioned by the partition walls is preferably 200 μm to 1 mm.

  When the height of the flow path is 200 μm or more, even if the dispersed phase liquid is injected from the micropores at a high flow rate so as to achieve high productivity, more uniform emulsion droplets can be generated. Further, when the height of the flow path is less than 200 μm, when the dispersed phase liquid is injected at a high flow rate, the partition wall is opposed to the partition wall in which the micropores are formed before being separated by the flow of the continuous phase liquid. Thus, coarse emulsion droplets that can be visually confirmed are generated, and uniform emulsion droplets cannot be generated. Therefore, productivity may not be improved.

  On the other hand, when the height of the flow path is 1 mm or less, excessive consumption of the continuous phase liquid can be further prevented. On the other hand, when the height of the flow path exceeds 1 mm, a sufficient shearing force cannot be applied on the outlet side of the micropores, and the target particle size and particle size distribution may not be obtained.

  The height of the flow path is preferably 300 μm or more, more preferably 400 μm or more, and preferably 900 μm or less, more preferably 800 μm or less.

  Here, the height of the flow path is the distance between the partition wall in which the micropores are formed and the partition wall facing this partition wall. The width of the flow path is the distance between the partition walls in the direction orthogonal to the flow direction of the continuous phase and in the direction orthogonal to the height of the flow path. Although it does not restrict | limit especially as a width | variety of a flow path, For example, it can be set as the range of 0.1-10 mm.

  For example, when the cross-sectional shape of the flow path is rectangular, the distance between the partition wall in which the micropores are formed and the partition wall facing this partition wall is the height of the flow channel. The same applies to the donut shape shown in FIG. Moreover, when the cross-sectional shape of a flow path is circular, the height and width of a flow path become a diameter of a circle.

  Although it does not restrict | limit especially as length of a flow path, For example, it can be set as the range of 1-500 mm. If it exceeds 500 mm, the pressure loss increases, which increases the possibility of leakage to the outside of the flow path, which is not preferable. On the other hand, when the thickness is less than 1 mm, the number of micropores that can be formed in the partition is reduced, and thus productivity is lowered, which is not preferable. In a configuration in which the cross-sectional shape of the flow path changes throughout the length of the flow path, the height of the flow path is the minimum height throughout the flow path length, and the width of the flow path is the minimum throughout the flow path length. The width of the part.

In this embodiment, when the flow rate of the continuous phase liquid is 0.3 to 10 m / s, the dispersed phase liquid is extruded at a flow rate of 0.1 to 5 m / s per hole of the micropores, thereby reducing the particle diameter. Emulsion droplets having a narrow distribution can be obtained, and the particle size distribution of spherical particles obtained by solidifying the emulsion droplets can be narrowed. Here, the flow velocity of the dispersed phase liquid is a value obtained by dividing the flow rate (m ³ / s) of the dispersed phase liquid flowing per unit time into one micropore by the cross-sectional area (m ² ) of the micropore. .

  When the flow rate of the dispersed phase liquid is less than 0.1 m / s, emulsion droplets having a wide particle size distribution may be generated. On the other hand, if it exceeds 5 m / s, coarse emulsion droplets may be generated, and spherical particles with a narrow particle size distribution may not be obtained.

  The flow rate per hole of the micropores is preferably 0.5 m / s or more, more preferably 1.0 m / s or more.

The Reynolds number of the continuous phase liquid flowing in the flow path is preferably 500 to 10,000. Here, the Reynolds number when the cross section of the flow path is circular is calculated by the following formula 1, and the inner diameter D of the flow path uses the minimum diameter in the cross section of the flow path. Here, D (inner diameter of the channel: m), u (average flow velocity: m / s), ρ (fluid density: kg / m ³ ), μ (fluid viscosity: Pa · s).
Reynolds number (−) = D · u · ρ / μ Equation 1

The Reynolds number when the cross section of the flow path is not circular is calculated by the following 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, is there.
Reynolds number (−) = 4 × r · u · ρ / μ Equation 2

  When the Reynolds number is 500 or more, sufficient shearing force can be applied to separate the dispersed phase liquid extruded from the micropores at a high flow rate, and the dispersed phase liquid is formed into emulsion droplets in the continuous phase liquid. Can be promoted.

  On the other hand, when the Reynolds number is 10,000 or less, disturbance of the liquid flow in the flow path can be prevented, and emulsion droplets having a uniform particle diameter can be formed, and spherical particles having a uniform particle diameter can be obtained. be able to.

  The Reynolds number is preferably 700 or more, more preferably 1000 or more, and preferably 7000 or less, more preferably 5000 or less.

(Emulsifying device)
Hereinafter, an example of the emulsification apparatus used in the present embodiment will be described with reference to FIG. In the following description, a method for producing a W / O emulsion using an aqueous liquid as a dispersed phase liquid and an organic liquid as a continuous phase liquid will be described. In addition, it is also possible to produce an O / W emulsion using the same emulsification apparatus and method, using an organic liquid as the dispersed phase liquid and an aqueous liquid as the continuous phase liquid.

  In FIG. 1, 1 and 2 are acrylic resin members, 3 is a stainless steel plate with a flow path 3a formed thereon, and 4 is a stainless steel plate with a plurality of minute holes 4a formed therein. The stainless steel plate 3 and the stainless steel plate 4 are overlapped so that the minute hole 4a of the stainless steel plate 4 faces the flow path 3a of the stainless steel plate 3, and the acrylic resin member 1 is arranged on the stainless steel plate 3 side, and the stainless steel plate 4 side. An acrylic resin member 2 is disposed on the surface. The stainless steel plates 3 and 4 are sandwiched between the acrylic resin members 1 and 2 to form a liquid flow path 3a.

  The acrylic resin member 1 is provided with a continuous phase inlet portion 5 and an emulsion outlet portion 6, and a continuous phase liquid is supplied from the continuous phase inlet portion 5 and flows toward the emulsion outlet portion 6. The acrylic resin member 2 is provided with a dispersed phase supply unit 7, and a dispersed phase liquid is supplied from the dispersed phase supply unit and is pushed out to the flow path 3 a through the micropores 4 a. In the flow path 3a, an emulsion is produced from the continuous phase and the dispersed phase and discharged from the emulsion outlet portion 6.

  Note that the dispersed phase liquid pushed out from the micropore 4a grows larger than the pore diameter at the outlet of the micropore 4a due to the interfacial tension. Thereafter, the dispersed phase liquid is separated by the flow of the continuous phase liquid to form emulsion droplets in the continuous phase liquid.

  As for the flow path 3a of the stainless steel plate 3, the multiple flow paths 3a may be formed along the flow direction of the continuous phase liquid. Moreover, as for the micropore part 4a of the stainless steel plate 4, the several microhole part 4a may be formed with respect to each flow path 3a.

  In this embodiment, the height of the flow path 3a can be set to 200 μm to 1 mm by setting the thickness of the stainless steel plate 3 forming the flow path 3a through which the continuous phase liquid flows to 200 μm to 1 mm. The thickness of the stainless steel plate 3 is more preferably 400 to 800 μm.

  The thickness of the stainless steel plate 4 is not particularly limited, and can be, for example, 10 to 500 μm. By being 10 μm or more, the strength of the steel sheet can be secured to prevent bending, the flatness of the steel sheet can be maintained, and the dispersed phase liquid that is press-fitted into the flow path 3a from the plurality of micropores 4a. The droplets can be prevented from coalescing, and droplets with a more uniform particle size can be formed. On the other hand, by being 500 micrometers or less, it is excellent in the workability of a steel plate, and can improve a processing precision at low cost. The thickness of the stainless steel plate 4 is preferably 30 to 200 μm.

  The method for forming the flow path 3a and the minute hole 4a is not particularly limited, and various processing methods such as laser processing, etching processing, electroforming processing, and press processing can be applied. However, from the viewpoint of simplicity of processing and cost It is preferable to use a laser processing method such as an excimer laser, a UV-YAG laser, a femtosecond laser, or a picosecond laser.

  When the dispersed phase liquid is an aqueous liquid, it is preferable that the stainless steel plate 4 has a water repellent treatment on at least the surface of the micropores 4a on the flow path 3a side. This water repellent treatment is preferably performed on at least a portion of the surface of the stainless steel plate 4 that comes into contact with the organic liquid as the continuous phase liquid. For example, after forming the microhole 4a in the stainless steel plate 4, the entire surface of the stainless steel plate 4 can be subjected to water repellent treatment.

  As a result, it is possible to promote the action of the dispersed phase liquid being cut off at the outlet portion of the micropore 4a, and to form emulsion droplets with a more uniform particle diameter. When the stainless steel plate 4 is hydrophilic, an aqueous liquid that is a dispersed phase liquid is pushed out from the micropores 4a and then flows along the surface of the stainless steel plate 4 so that the particle size of the emulsion droplets is not uniform. There is a phenomenon. This phenomenon has been confirmed by observation with a high-speed camera.

  The water repellent treatment can be performed by coating the surface of the stainless steel plate 4 with a water repellent treatment agent in which a hydrophobic resin or a silane coupling agent is dissolved in a solvent. As the hydrophobic resin, it is preferable to use a thermoplastic resin. This is because even if the micropores 4a are blocked during coating, the holes can be penetrated by heat treatment. As the hydrophobic resin, it is preferable to use a solvent-soluble fluororesin from the viewpoint of durability. Any method can be used for coating, but a thin and uniform coating can be achieved by dip coating the water repellent treatment agent.

  In the water repellent treatment, it is preferable to form a water repellent treated film having a thickness of 0.001 to 5 μm on the surface of the stainless steel plate 4. When the thickness is 0.001 μm or more, durability and mechanical strength can be increased, and generation of pinholes can be prevented. On the other hand, when the thickness is 5 μm or less, it is possible to prevent the micropores 4a from being blocked by being covered with the water repellent agent.

  The cross-sectional shape of the micropore 4a is preferably a shape that does not have a convex surface on the inside, and examples thereof include a circle, an ellipse, a rectangle, a triangle, and a polygon. Of these, a circle is preferable. Such a shape makes it possible to form emulsion droplets with excellent processability and a more uniform particle size.

  In addition, the minute hole portion 4a may have a shape in which the opening on the flow path 3a side of the stainless steel plate 4 is made smaller than the opening on the opposite surface side and has an inclination in the thickness direction of the stainless steel plate 4. Thereby, the pressure at the time of extruding a dispersed phase liquid to the flow path 3a through the micropore part 4a can be reduced.

  When the cross-sectional shape of the micropore 4a is other than circular, the emulsion droplet has a curvature distribution when the dispersed phase liquid becomes an emulsion droplet at the opening on the flow path 3a side of the micropore 4a, It is estimated that it is spontaneously separated from the dispersed phase liquid relatively early and becomes emulsion droplets in the continuous phase liquid. Therefore, compared to the case of the circular micropore 4a, there is an advantage that it is easy to obtain an emulsion droplet having a relatively small particle size.

  The quadruple value of the hydrodynamic radius r in the cross section of the microhole 4a is preferably 0.1 to 100 μm. More preferably, it is 1-80 micrometers. The hydrodynamic radius r of the cross section of the microhole 4a is a value at the opening of the microhole 4a on the flow path 3a side.

Here, the hydrodynamic radius r is the hydrodynamic radius r (m) of the cross-section of the micropore = the cross-sectional area of the micropore (like the “flow-path hydrodynamic radius (m)” defined in Equation 2 above) m ² ) / perimeter (m) in contact with the fluid in the cross section of the micropore. Therefore, when the cross-sectional shape of the minute hole portion 4a is circular, the hydrodynamic radius r = the inner diameter D / 4 of the circle, and thus the quadruple value of the hydrodynamic radius r corresponds to the inner diameter D of the circle.

  When the quadruple value of the hydrodynamic radius r in the cross section of the microhole portion 4a is 0.1 μm or more, the supply amount of the dispersed phase liquid can be increased and the productivity can be increased. On the other hand, by being 100 μm or less, it is possible to prevent an excessive increase in the particle size of the emulsion droplets and to form emulsion droplets with a more uniform particle size.

  From the viewpoint of productivity, it is preferable to provide a plurality of micropores 4 a for supplying the dispersed phase liquid containing the spherical particle precursor so as to penetrate in the thickness direction of the stainless steel plate 4. The number of micropores 4a for one flow path 3a can be, for example, 1000 or more, more preferably 5000 or more, still more preferably 20000 or more, and may be 50000 or more.

  Although it does not specifically limit as an arrangement | sequence of the micropore part 4a formed in the stainless steel plate 4 facing the flow path 3a, From a viewpoint of productivity and workability, the width direction of the stainless steel plate 4 (width direction of the flow path 3a) ) And / or a plurality of micropores 4a can be formed at regular intervals or randomly in the length direction (the flow direction of the continuous phase liquid).

  For example, a plurality of microholes 4a can be formed in a parallel arrangement at a constant pitch in the width direction and the length direction of the stainless steel plate 4. Of the microholes 4a arranged in parallel in the width direction and the length direction of the stainless steel plate 4, two microholes 4a adjacent in the width direction and two microholes 4a adjacent in the length direction are provided. It is possible to form a staggered arrangement by forming another minute hole 4a at the center of a rectangular diagonal line formed by connecting the centers of these minute holes 4a. In this staggered arrangement, the microscopic holes 4a can be arranged densely, and the aperture ratio of the stainless steel plate 4a can be increased to further increase the productivity.

  The interval (pitch) between adjacent microhole portions 4a when forming the plurality of microhole portions 4a is not particularly limited, but is an interval of 1/2 or more of the diameter of a circle circumscribing the cross-sectional shape of the microhole portions 4a. It is preferable to form the adjacent micropores 4 a in the stainless steel plate 4. More preferably, an interval equal to or larger than the diameter of a circle circumscribing the cross-sectional shape of the microhole portion 4a is provided.

  Since the interval between the adjacent micropores 4a is in the above-described range, the emulsion droplets are prevented from coalescing after the emulsion droplets are formed, and the particle size of the emulsion droplets is made more uniform. can do. On the other hand, productivity can be improved by closely arranging the plurality of minute hole portions 4a within a range where coalescence of emulsion droplets can be prevented.

  As an emulsifying apparatus that can be used in the present embodiment, the stainless steel plate 4 can be installed so as to be parallel or perpendicular to the horizontal plane as in the emulsifying apparatus shown in FIG. When placed perpendicular to the horizontal plane, the flow of the continuous phase may be from top to bottom or from bottom to top.

  When the stainless steel plate 4 is installed so as to have an angle with respect to the horizontal plane, pressure due to the liquid depth is applied to each of the dispersed phase liquid side and the continuous phase liquid side on the predetermined horizontal plane in the height direction. Assuming that the liquid phase of the disperse phase liquid and the continuous phase liquid is approximately equal in a specific horizontal plane, it is caused by the difference in density between the disperse phase liquid and the continuous phase liquid, ((dispersion phase liquid density−continuous phase liquid density) × liquid A pressure corresponding to (depth) is applied. Therefore, if the density of the continuous phase liquid is smaller than the density of the dispersed phase liquid, the continuous phase liquid flow path 3a is parallel to the horizontal plane by flowing the continuous phase liquid from below to above, and in the opposite case from above. Compared with the case where it forms, the change of the pressure difference of the dispersed phase liquid side and continuous phase liquid side in all the flow paths can be made relatively narrow. As a result, the supply amount of the dispersed phase liquid from each micropore 4a formed in the stainless steel plate 4 is stabilized, the particle diameter of the emulsion droplets is made more uniform, and the resulting spherical particles have a more uniform particle diameter. Can be

  The particle diameter of the emulsion droplets is influenced by the ratio of the flow velocity in the flow direction of the continuous phase liquid to the flow velocity in the flow direction of the dispersed phase liquid in addition to the installation conditions of the micropores 4a.

  The flow rate ratio is preferably 0.1 to 100. More preferably, it is 0.5-50, More preferably, it is 1-10.

  When the ratio is 100 or less, the supply amount can be adjusted so that the continuous phase liquid is not excessively consumed. On the other hand, by being 0.5 or more, the dispersed phase liquid can be separated by the flow of the continuous phase liquid to promote the formation of emulsion droplets, and the particle size of the emulsion droplets can be made more uniform. .

  The high productivity of the spherical particles can be seen from the large amount of dispersed phase liquid supplied per unit area of the micropore formation region. Further, increasing the supply amount leads to miniaturization of the apparatus.

  Here, as the supply amount of the dispersed phase liquid per unit area of the micropore formation region, the supply amount of the dispersed phase liquid supplied to the micropores 4a per unit time is defined as the area of the micropore formation region. The value divided by. The microhole part forming area is a rectangular area surrounded by a straight line in contact with the outer peripheral part of the microhole part 4a on the exit side surface of the microhole part 4a of the partition wall. For example, in the case where a plurality of microholes 4a are arranged and formed into a quadrangle as a whole, a rectangular region surrounded by a straight line in contact with the outer peripheral part of the outer microhole 4a is the microhole formation region. . Further, in the case where a plurality of minute hole portions 4a are arranged and formed in a circular shape or a triangular shape as a whole, the minute hole forming region is similarly determined so that the rectangular region has a minimum area.

The supply amount of the dispersed phase liquid per unit area of the micropore formation region can be 3 m ³ / m ² · hr or more. Preferably it is 20 m ³ / m ² · hr or more, more preferably 40 m ³ / m ² · hr or more. In this embodiment, since the flow rate of the continuous phase liquid is 0.3 to 10 m / s, even if the supply amount of the dispersed phase liquid is increased to increase the productivity, the emulsion droplet size can be improved by improving the emulsion stability. As a result, spherical particles having a more uniform particle diameter can be obtained.

The upper limit of the supply amount of the dispersed phase liquid per unit area of the micropore formation region is preferably 300 m ³ / m ² · hr or less in order to obtain spherical particles having a uniform particle diameter, Preferably, it is 250 m ³ / m ² · hr or less.

(Solidification process)
Next, the emulsion droplets containing the spherical particle precursor are solidified to form spherical particles. In this solidification step, it is preferable to form one spherical particle from one emulsion droplet. For example, there is a method of obtaining spherical particles by gelling emulsion droplets containing spherical particle precursors.

  As the solidification step, a method of adding a precipitant and precipitating the spherical particle precursor can be used. Examples of the precipitating agent include alkali metal halides or carbonates, inorganic acids, organic acids, ammonium salts of inorganic acids, ammonium salts of organic acids, alkaline earth metal halides, and the like. Specific examples include aqueous solutions of ammonium hydrogen carbonate, ammonium sulfate, potassium chloride, potassium hydrogen carbonate and the like, but are not limited thereto.

  When the spherical particle precursor in the dispersed phase liquid is alkali silicate or silica, the emulsion droplets that are spherical are gelled while maintaining this shape by gelling the emulsion to obtain a spherical silica hydrogel. It is done. For gelation, it is preferable to introduce a gelling agent into the emulsion. As the gelling agent, an acid such as an inorganic acid or an organic acid is used, and sulfuric acid, hydrochloric acid, nitric acid, carbonic acid, etc., which are inorganic acids, are particularly preferable. From the standpoint of ease of operation, the most simple and preferred method is a method using carbon dioxide gas. As the carbon dioxide, pure carbon dioxide having a concentration of 100% may be introduced, or carbon dioxide diluted with air or an inert gas may be introduced. The time required for gelation is usually preferably 1 to 30 minutes, and the temperature during gelation is preferably 5 to 30 ° C.

(Recovery process)
Next, the spherical particles are collected. In this recovery step, the spherical particles can be recovered by separating the solidified spherical particles from the continuous phase. Preferably, the spherical particles and the continuous phase are subjected to solid-liquid separation.

  When the spherical particle precursor in the dispersed phase liquid is alkali silicate or silica, the reaction system is allowed to stand after the gelation is completed, and the silica hydrogel is separated into a continuous phase and a dispersed phase containing silica hydrogel. It is preferable to separate. When saturated hydrocarbon is used as the continuous phase liquid and water is used as the dispersed phase liquid, the continuous phase is separated in the upper layer and the aqueous liquid phase containing silica hydrogel is separated in the lower layer. . In that case, it is preferable to separate using a separation device.

  The aqueous slurry of silica hydrogel is preferably aged. In the aging treatment, if desired, an acid such as sulfuric acid is added to adjust the pH to about 1 to 5 to complete the gelation, and then steam distillation at a temperature of 60 to 150 ° C., preferably 80 to 120 ° C. Then, a slight amount of saturated hydrocarbon remaining in the water slurry is distilled off and further heated at an appropriate pH of about pH 7-9 to age the silica hydrogel.

  If necessary, after performing the above-mentioned aging treatment, the water slurry is filtered to obtain a silica hydrogel, which is dried at a temperature of about 100 to 150 ° C. for about 1 to 30 hours to obtain silica spherical particles. be able to.

  In addition, when an alkali silicate aqueous solution is used as the aqueous liquid of the dispersed phase liquid and an acid is used as the gelling agent, an alkali metal salt (for example, sodium carbonate if the gelling agent is carbonic acid) is by-produced. In order to prevent the salt from being mixed into the silica spherical particles, it is preferable to sufficiently wash the wet cake (silica hydrogel containing water) when filtered. In some cases, water may be added again to the wet cake after washing to form a slurry to repeat filtration and washing again. At this time, if necessary, an operation of adjusting the pH of the slurry to about 1 to 5 and aging again may be performed.

  In the case of an O / W emulsion, for example, emulsion droplets, which are dispersed phase droplets containing a polymerizable monomer, are polymerized and solidified, and recovered from an aqueous liquid that is a continuous phase, thereby obtaining resin spherical particles. it can.

(Physical properties of spherical particles)
The shape of the obtained spherical particles is not particularly limited as long as it is spherical, and may be spherical including true spheres and ellipsoids. The shape of the spherical particles can be confirmed by observing the shape using a scanning electron microscope or the like.

  The obtained spherical particles preferably have a D90 / D10 of 1.8 or less, more preferably 1.75 or less, and still more preferably 1.70 or less. Here, D90 is a 90% volume conversion particle diameter, and is a particle diameter when the particle volume is 90% of the total volume when the volume of the particle is integrated from the smaller particle diameter side, D10 is The particle diameter is 10% by volume, and the particle diameter is similarly 10%. The spherical particles D90 and D10 are values measured using a Coulter counter manufactured by Beckman Coulter.

  According to the present embodiment, even when the supply amount of the dispersed phase liquid is increased and the productivity is increased, the spherical particle D90 / D10 is set to 1.8 or less, the particle size distribution is narrow, and the spherical particle having a more uniform particle size. Particles can be provided.

  The production method according to the present embodiment can obtain the effect without limitation on the volume-converted average particle diameter of spherical silica (D50: 50% volume-converted particle diameter). The D50 of the spherical particle is a particle diameter when the particle volume is 50% of the total volume when the volume of the particle is integrated from the smaller particle diameter side, and can be obtained in the same manner as D90 and D10 described above. .

  The volume-converted average particle diameter (D50) of the spherical particles suitable for the production method according to the present embodiment is 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more.

  Further, the volume-converted average particle diameter (D50) of the spherical particles suitable for the production method according to the present embodiment is 100 μm or less, more preferably 80 μm or less, and further preferably 50 μm or less.

As the pore volume of the spherical particles suitable for the production method of the present embodiment is not particularly limited, a 0.1 to 5 cm ³ / g, more preferably 0.5~4cm ³ / g. In particular, the manufacturing method according to the present embodiment is suitable for manufacturing porous silica spherical particles.

  The spherical particles obtained by the production method described above are, for example, toner, heat insulating material, food additive, medical diagnostic agent, filler for paint, filler for cosmetics, filler for resin film, spacer for liquid crystal, filler for chromatography, It can be widely used for catalysts, catalyst carriers, resin fillers, adsorbents, desiccants and the like.

  Since the spherical particles according to the present embodiment are substantially spherical and have a uniform particle diameter, they are preferably used as a catalyst carrier when producing a resin such as polyethylene or polypropylene that has a polymer shape reflecting the shape of the catalyst carrier. it can.

(Other embodiments)
As a method for producing spherical particles according to another embodiment of the present invention, a dispersed phase liquid containing a spherical particle precursor is passed through a micropore formed in a partition wall into a continuous phase liquid flowing in a flow path partitioned by partition walls. This is a method for producing spherical particles in which an emulsion is produced by extruding at a flow rate of 0.1 to 5 m / s per hole, emulsion droplets containing spherical particle precursors are solidified to form spherical particles, and the spherical particles are recovered. The Reynolds number of the continuous phase liquid flowing in the flow path is 500 to 10,000.

  In this embodiment, without limiting to the flow rate of the continuous phase liquid, uniform spherical particles can be obtained with high productivity by setting the Reynolds number of the continuous phase liquid flowing in the flow channel to 500 to 10,000.

  In this case, it is preferable that the flow rate of the continuous phase liquid flowing in the flow path partitioned by the partition wall is 0.3 to 10 m / s. Furthermore, the height of the flow path partitioned by the partition walls is preferably 200 μm to 1 mm.

  Details of each condition described above, raw materials, characteristics of the obtained spherical particles, and the like are common to the above-described embodiment.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

<Test of supply amount and surfactant concentration of dispersed phase and continuous phase>
Through the following tests, the average particle size (D50) and D90 / D10 of the silica particles, which are spherical particles, are obtained with respect to the supply amount of sodium silicate as a dispersed phase and n-decane as a continuous phase and the surfactant concentration. evaluated. The production conditions and evaluation results of the silica particles are shown in Table 1.
Table 4 summarizes the setting conditions of each emulsifying device used in the following examples and the like.

Example 1
"1. Preparation of dispersed phase and continuous phase"
As a dispersed phase, No. 3 sodium silicate (manufactured by AGC S-Tech Co., Ltd., sodium silicate aqueous solution, Na 2 O / SiO 2 (molar ratio) = 3.09) was diluted with water to have a SiO 2 concentration of 24% by mass. used. The density at this time was 1315 kg / m ³ . N-decane (C10H22, density 730 kg / m ³ ) was used as the organic liquid in the continuous phase. Moreover, what dissolved 0.3 mass% of sorbitan monooleate (Sanyo Chemical Industries, Ltd., Ionette S80) as a surfactant was prepared in advance in this n-decane.

“2. Emulsification device A”
In Example 1, emulsification was performed using the emulsifier A. A schematic cross-sectional view of the emulsifier A is as shown in FIG. Table 4 shows the setting conditions of the emulsifier A.

  In the emulsification apparatus A, the stainless steel plate 3 is etched on a SUS304 sheet having a thickness of 600 μm by one through-processed portion (3a) having a width of 3.0 mm and a length of 74 mm corresponding to a channel (microchannel). That is, a flow path 3a having a width of 3.0 mm and a height of 600 μm is formed.

The stainless steel plate 4 has a microporous portion 4a processed at a position where the microporous portion 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 on a SUS304 sheet having a thickness of 50 μm. Is. The micro hole portion 4a has an area of 2.61 mm × 37.9 mm (9.89 × 10 ⁻⁵ m ² ) in the central portion of the flow path and a hole diameter on the outlet side (lower side, that is, the stainless steel plate 3 side) of 8 μm. A certain number of circular through-hole portions 4b are machined at a pitch of 65 μm.

  Water repellent treatment was performed on the surface of the stainless steel plate 3 on which the flow path a was formed and on the surface of the stainless steel plate 4 on which the micropores 4a were formed. The water-repellent treatment is performed by using a solution obtained by dissolving a solvent-soluble fluororesin (“Cytop” manufactured by Asahi Glass Co., Ltd.) in a solvent (“CT-Solv100” manufactured by Asahi Glass Co., Ltd.) so that the coating thickness after drying is 0.1 μm. In this way, it was coated by a dip coating method.

  The stainless steel plate 3 and the stainless steel plate 4 are overlapped as shown in FIG. 1, and each of the acrylic member 2 for forming the dispersed phase flow path having the dispersed phase inlet portion 7, the continuous phase inlet portion 5 and the emulsion outlet portion 6 is provided. The emulsification apparatus A was produced by sandwiching between the acrylic member 1 having a flow path. The four sides of the emulsifier A were clamped and fixed with a uniform force, and it was confirmed that there was no leakage by supplying water in advance.

“3. Preparation of emulsion”
The emulsifier A prepared in the above “2” is used with the flow path in the horizontal direction, and the n-decane in which the surfactant prepared in the above “1” is dissolved is dispersed from the continuous phase inlet portion 5. By supplying the No. 3 sodium silicate prepared in the above “1” from the phase inlet portion 7 through the micropores 4a, No. 3 sodium silicate is dispersed in n-decane in which the surfactant is dissolved. A mold emulsion was continuously produced.

At this time, the supply amount of n-decane was 16.2 L / h per flow channel, and the linear velocity (flow velocity) in the flow direction in the flow channel was 2.5 m / s. The experiment was performed at room temperature. At this time, the Reynolds number of the flow of n-decane was calculated from the following formula 2a from the hydrodynamic radius of the flow path: 250 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s, 1967. Met. The amount of No. 3 sodium silicate supplied was 3.99 L / h (40.3 m ³ / m ² · h) per unit area of the micropore formation region (9.89 × 10 ⁻⁵ m ^{2 in the} emulsifying apparatus A). The linear velocity (flow velocity) in the flow direction per one hole (4b) of the microhole portion 4a was 0.92 m / s.

Reynolds number (−) = 4 × r · u · ρ / μ Equation 2a.
Here, r is the flow path radius (m) = the cross-sectional area of the flow path (m ² ) / the circumference of the flow path in contact with the fluid (m), u (average flow velocity: m / s), ρ (Fluid density: kg / m ³ ) and μ (fluid viscosity: Pa · s). The average flow velocity u is a flow velocity in the flow direction in the continuous phase flow path.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 2.7.

"4. Gelation and recovery"
After collecting the W / O type emulsion prepared in “3” above, gelation was performed by blowing carbon dioxide gas having a concentration of 100% by mass at a supply rate of 300 mL / min for 15 minutes while stirring. To the produced silica hydrogel, 200 mL of water was added and allowed to stand for 10 minutes, and then two phases were separated due to the difference in specific gravity to obtain an aqueous slurry (aqueous phase) of silica hydrogel. Next, a 0.1 N aqueous sulfuric acid solution was added to the resulting silica hydrogel water slurry, adjusted to pH 2 at 25 ° C., and allowed to stand for 30 minutes. Subsequently, filtration and water washing were performed, and the silica porous spherical body was obtained by drying at 120 degreeC for 20 hours.

“5. Shape confirmation”
The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Further, when this silica porous spherical body was measured with a Coulter counter (manufactured by Beckman Coulter, the same shall apply hereinafter), the 50% volume equivalent particle diameter (D50: average particle diameter) was 36.1 μm, and the 90% volume equivalent particle diameter. The ratio (D90 / D10) of (D90) and 10% volume equivalent particle diameter (D10) was 1.45. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Example 2)
A W / O emulsion was prepared, gelled, and recovered in the same manner as in Example 1 except that the surfactant concentration was changed to 0.7% by mass.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 36.2 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.43. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Example 3)
A W / O emulsion was prepared, gelled, and recovered in the same manner as in Example 1 except that the surfactant concentration was 1.0% by mass.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 36.0 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.42. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Reference Example 1)
"1. Preparation of dispersed phase and continuous phase"
A dispersed phase and a continuous phase were prepared in the same manner as in Example 1.

“2. Emulsification device B production”
In Reference Example 1, emulsification was performed using the emulsification apparatus B. A schematic cross-sectional view of the emulsifying device B is as shown in FIG. Table 4 shows the setting conditions of the emulsifier B.

  In the emulsification apparatus B, the stainless steel plate 3 is obtained by etching one through hole (3a) having a width of 3.0 mm corresponding to a flow path (microchannel) with respect to a SUS304 sheet having a thickness of 200 μm. Yes, that is, a flow path 3a having a width of 3.0 mm and a height of 200 μm is formed.

The stainless steel plate 4 has a microhole portion 4a at a position where the microhole portion 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 with respect to a sheet made of SUS304 having a thickness of 50 μm. The surface is hydrophobized. The microhole portion 4a has an area of 2.62 mm × 22.9 mm (6.23 × 10 ⁻⁵ m ² ) at the center of the flow path and a hole diameter on the outlet side (lower side, that is, the stainless steel plate 3 side) of 20 μm. There are 6440 circular through-holes processed at a pitch of 100 μm. In addition, the stainless steel plates 3 and 4 were subjected to water repellent treatment in the same manner as the emulsification apparatus A.

  The stainless steel plate 3 and the stainless steel plate 4 are overlapped as shown in FIG. 1, and each of the acrylic member 2 for forming the dispersed phase flow path having the dispersed phase inlet portion 7, the continuous phase inlet portion 5 and the emulsion outlet portion 6 is provided. The emulsification apparatus B was produced by sandwiching with an acrylic member 1 having a flow path. The four sides of the emulsifier B were clamped and fixed with a uniform force, and it was confirmed that there was no leakage by supplying water in advance.

“3. Preparation of emulsion”
The emulsifier B prepared in the above “2” is used with the flow path in a horizontal direction, and the n-decane in which the surfactant prepared in the above “1” is dissolved is dispersed from the continuous phase inlet 5. By supplying the No. 3 sodium silicate prepared in the above “1” from the phase inlet portion 7 through the micropores 4a, No. 3 sodium silicate is dispersed in n-decane in which the surfactant is dissolved. A mold emulsion was continuously produced.

At this time, the supply amount of n-decane was 0.432 L / h per flow path, and the flow velocity in the flow direction in the flow path was 0.20 m / s. The experiment was performed at room temperature, and at this time, the Reynolds number of the flow of n-decane was calculated from the above formula 2a from the hydrodynamic radius of the flow path: 93.8 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s. However, it was 59. Moreover, the supply amount of No. 3 sodium silicate is 0.0142 L / h (0.228 m ³ / m ² · h) per unit area of the micropore formation region (6.23 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus B). ), And the flow velocity in the flow direction per one hole (4b) of the minute hole portion 4a was 0.0020 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 103.

"4. Gelation and recovery"
Gelation and recovery were performed in the same manner as in Example 1 above.

“5. Shape confirmation”
The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 39.7 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.40. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Reference Example 2)
A W / O emulsion was prepared, gelled, and recovered in the same manner as in Reference Example 1, except that the surfactant concentration was changed to 0.7% by mass.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 36.3 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.41. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Reference Example 3)
A W / O emulsion was prepared, gelled, and recovered in the same manner as in Reference Example 1 except that the surfactant concentration was 1.0% by mass.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 34.6 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.40. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Comparative Example 1)
In Comparative Example 1, a W / O emulsion was prepared, gelled, and recovered in the same manner as in Reference Example 1, except for the following points.

The supply amount of n-decane was 4.32 L / h per flow path, and the flow velocity in the flow direction in the flow path was 2.0 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 590. Moreover, the supply amount of No. 3 sodium silicate is 0.0142 L / h (0.228 m ³ / m ² · h) per unit area of the micropore formation region (6.23 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus B). ), And the flow velocity in the flow direction per one hole (4b) of the minute hole portion 4a was 0.0020 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction in the microhole portion 4a of sodium silicate supplied from the microhole portion 4a was 1025.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 10.2 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.92. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

  As shown in Table 1, according to Examples 1 to 3, even when the flow rate of the continuous phase is increased to increase the Reynolds number, the supply amount of the disperse phase is increased to increase the production amount. Of silica particles could be obtained. The silica particles had a small D90 / D10 and were uniform. As in Reference Examples 1 to 3, under conditions where the flow rate of the continuous phase is slow and the Reynolds number is small, in order to obtain uniform silica particles, the supply amount of the dispersed phase must be reduced, and the productivity is sufficiently increased. I couldn't. Further, even when the flow rate of the continuous phase was high and the Reynolds number was large as in Comparative Example 1, uniform silica particles could not be obtained if the amount of dispersed phase supplied was small.

  From Examples 1 to 3, it was found that the 50% volume conversion particle diameter (D50) was constant even when the surfactant concentration was changed. This is because the flow rate of n-decane, which is a continuous phase, is high, so that the shearing force for forming droplets of sodium silicate, which is a dispersed phase, is strong, and the difference in surfactant concentration has an effect on droplet formation. It is thought that it is small.

  From Reference Examples 1 to 3, it was revealed that the 50% volume conversion particle diameter (D50) increases as the surfactant concentration decreases. This is contrary to Examples 1 to 3, since the flow rate of n-decane is slow, the shearing force for forming sodium silicate into droplets is weak, and the interface to the sodium silicate injected from the micropores 4a. This is presumably because the concentration of the activator is a factor that affects droplet formation.

<Test of supply amount of dispersed phase and continuous phase>
Through the following tests, the average particle diameter (D50) and D90 / D10 of the silica particles, which are spherical particles, were evaluated with respect to the supply amount of sodium silicate as a dispersed phase and n-decane as a continuous phase. The production conditions and evaluation results of the silica particles are shown in Table 2.

Example 4
"1. Preparation of dispersed phase and continuous phase"
The dispersed phase was prepared in the same manner as in Example 1 except that No. 3 sodium silicate was diluted with water to make the SiO 2 concentration 17% by mass. The density of No. 3 sodium silicate at this time was 1215 kg / m ³ . The continuous phase was prepared as in Example 1.

"2. Production of emulsifier C"
In Example 4, emulsification was performed using the emulsification apparatus C. A schematic cross-sectional view of the emulsifier C is as shown in FIG. Table 4 shows the setting conditions of the emulsifier C.

  In the emulsification apparatus C, the stainless steel plate 3 is etched on a 600 μm-thick SUS304 sheet by one through-processed part (3a) having a width of 1.7 mm and a length of 74 mm corresponding to a flow channel (microchannel). That is, a flow path 3a having a width of 1.7 mm and a height of 600 μm is formed.

The stainless steel plate 4 has a microhole portion 4a at a position where the microhole portion 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 with respect to a sheet made of SUS304 having a thickness of 50 μm. The surface is hydrophobized. The minute hole portion 4a has an area of 1.31 mm × 37.9 mm (4.96 × 10 ⁻⁵ m ² ) in the central portion of the flow path and a hole diameter on the outlet side (lower side, that is, the stainless steel plate 3 side) of 12.2. 5320 circular through-hole portions 4b of 7 μm are processed at a pitch of 100 μm. In addition, the stainless steel plates 3 and 4 were subjected to water repellent treatment in the same manner as the emulsification apparatus A.

  The stainless steel plate 3 and the stainless steel plate 4 are overlapped as shown in FIG. 1, and each of the acrylic member 2 for forming the dispersed phase flow path having the dispersed phase inlet portion 7, the continuous phase inlet portion 5 and the emulsion outlet portion 6 is provided. The emulsification apparatus C was produced by sandwiching with an acrylic member 1 having a flow path. The four sides of the emulsifier C were clamped and fixed with a uniform force, and it was confirmed that there was no leakage by supplying water in advance.

“3. Preparation of emulsion”
The emulsifying device C prepared in the above “2” is used so that the flow path is in the horizontal direction, and n-decane in which the surfactant prepared in the above “1” is dissolved from the continuous phase inlet portion 5 is used. By supplying the No. 3 sodium silicate prepared in the above “1” from the dispersed phase inlet 7 through the micropores 4a, the No. 3 sodium silicate is dispersed in n-decane in which the surfactant is dissolved. An O-type emulsion was continuously produced.

At this time, the supply amount of n-decane was 9.21 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 2.5 m / s. The experiment was performed at room temperature. At this time, the Reynolds number of the flow of n-decane was calculated from the above equation 2a from the hydrodynamic radius of the flow path: 222 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s, 1752. Met. Moreover, the supply amount of No. 3 sodium silicate was 2.37 L / h (47.7 m ³ / m ² · h) per unit area of the micropore formation region (4.96 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus C). The flow velocity in the flow direction per one hole (4b) of the microhole portion 4a was 1.0 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 2.6.

"4. Gelation and recovery"
Gelation and recovery were performed in the same manner as in Example 1 above.

“5. Shape confirmation”
The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 30.4 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.42. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Example 5)
In Example 5, production of W / O emulsion, gelation, and recovery were performed in the same manner as in Example 4 except for the following points.

At this time, the supply amount of n-decane was 4.19 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 1.1 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 768. In addition, the supply amount of No. 3 sodium silicate is 2.47 L / h (49.7 m ³ / m ² · h) per unit area of the micropore formation region, and per 1 hole (4b) of the micropore 4a. The flow velocity in the flow direction was 1.0 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 1.1.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 43.8 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.77. The pore volume measured by the nitrogen adsorption method was 0.9 cm ³ / g.

(Example 6)
In Example 6, production of W / O emulsion, gelation, and recovery were performed in the same manner as in Example 4 except for the following points.

At this time, the supply amount of n-decane was 18.4 L / h per flow path, and the flow velocity in the flow direction in the flow path was 5.0 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 3,500. In addition, the supply amount of No. 3 sodium silicate is 2.47 L / h (49.7 m ³ / m ² · h) per unit area of the micropore formation region, and per 1 hole (4b) of the micropore 4a. The flow velocity in the flow direction was 1.0 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 4.9.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 20.9 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.57. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Example 7)
In Example 7, except for the following points, a W / O emulsion was produced, gelled, and recovered in the same manner as in Example 4.

At this time, the supply amount of n-decane was 22.2 L / h per flow path, and the flow velocity in the flow direction in the flow path was 6.0 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 4223. In addition, the supply amount of No. 3 sodium silicate is 2.45 L / h (49.3 m ³ / m ² · h) per unit area of the micropore formation region, and per 1 hole (4b) of the micropore 4a. The flow velocity in the flow direction was 1.0 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 6.0.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 16.8 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.74. The pore volume measured by the nitrogen adsorption method was 0.9 cm ³ / g.

(Example 8)
In Example 8, except for the following points, W / O emulsion was prepared, gelled, and recovered in the same manner as Example 4.

At this time, the supply amount of n-decane was 10.9 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 3.0 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 2074. Further, the supply amount of No. 3 sodium silicate is 5.98 L / h (120 m ³ / m ² · h) per unit area of the micropore formation region, and the flow per one hole (4b) of the micropore 4a. The flow velocity in the direction was 2.5 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 1.2.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 30.9 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.60. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Reference Example 4)
“1. Preparation of dispersed phase and continuous phase”
As the dispersed phase, No. 3 sodium silicate (manufactured by AGC S-Tech Co., Ltd., Na 2 O / SiO 2 (molar ratio) = 3.09) was diluted with water to make the SiO 2 concentration 24.4% by mass. The density at this time was 1320 kg / m ³ . Isononane (C9H20, density 730 kg / m ³ ) was used as the organic liquid in the continuous phase. Moreover, what dissolved 0.5 mass% of sorbitan monooleate (Sanyo Chemical Industries, Ltd., Ionette S80) as a surfactant in advance was prepared in this isononane.

“2. Emulsification device D production”
In Reference Example 4, emulsification was performed using the emulsification apparatus D. A schematic cross-sectional view of the emulsifying device D is as shown in FIG. Table 4 shows the setting conditions of the emulsifying device D.

  In the emulsification apparatus D, the stainless steel plate 3 is etched on a SUS304 sheet having a thickness of 400 μm by one through-processed portion (3a) having a width of 3.0 mm and a length of 74 mm corresponding to a flow channel (microchannel). That is, a flow path 3a having a width of 3.0 mm and a height of 600 μm is formed.

The stainless steel plate 4 has a microhole portion 4a at a position where the microhole portion 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 with respect to a sheet made of SUS304 having a thickness of 50 μm. The surface is hydrophobized. The microhole 4a has an area of 2.73 mm × 22.9 mm (6.25 × 10 ⁻⁵ m ² ) at the center of the flow path and a hole diameter of 30 μm on the outlet side (lower side, that is, the stainless steel plate 3 side). 6440 circular through-hole portions 4b are processed at a pitch of 100 μm. In addition, the stainless steel plates 3 and 4 were subjected to water repellent treatment in the same manner as the emulsification apparatus A.

  The stainless steel plate 3 and the stainless steel plate 4 are overlapped as shown in FIG. 1, and each of the acrylic member 2 for forming the dispersed phase flow path having the dispersed phase inlet portion 7, the continuous phase inlet portion 5 and the emulsion outlet portion 6 is provided. The emulsification apparatus D was produced by sandwiching between the acrylic member 1 having a flow path. The four sides of the emulsifier D were clamped and fixed with a uniform force, and it was confirmed that there was no leakage by supplying water in advance.

“3. Preparation of emulsion”
The emulsifying device D produced in the above “2” is used with the flow path being in the horizontal direction, and the isononane prepared by dissolving the surfactant prepared in the above “1” from the continuous phase inlet portion 5 is added to the dispersed phase inlet. By supplying the No. 3 sodium silicate prepared in the above “1” from the part 7 through the micropores 4a, the No. 3 sodium silicate continuously has a W / O emulsion dispersed in isononane in which the surfactant is dissolved. Manufactured.

At this time, the supply amount of isononane was 1.35 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 0.31 m / s. The experiment was performed at room temperature, and at this time, the Reynolds number of the flow of isononane was 214 calculated from the above equation 2a from the hydrodynamic radius of the flow path: 176 μm and the viscosity: 7.5 × 10 ⁻⁴ Pa · s. It was. Moreover, the supply amount of No. 3 sodium silicate is 0.0322 L / h (0.515 m ³ / m ² · h) per unit area of the micropore formation region (6.25 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus D). ), And the flow velocity in the flow direction per one hole (4b) of the minute hole portion 4a was 0.0020 m / s.

  At this time, the ratio of the flow rate in the flow direction of isononane to the flow rate in the flow direction in the microhole portion 4a of sodium silicate supplied from the micropore portion 4a was 159.

"4. Gelation and recovery"
Gelation and recovery were performed in the same manner as in Example 1 above.

“5. Shape confirmation”
The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 49.8 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.40. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Comparative Example 2)
In Comparative Example 2, a W / O emulsion was prepared in the same manner as in Example 4 except for the following points.

At this time, the supply amount of n-decane was 0.730 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 0.20 m / s. The experiment was performed at room temperature, and at this time, the calculated value of the Reynolds number of the flow of n-decane was 139. In addition, the supply amount of No. 3 sodium silicate is 2.47 L / h (49.7 m ³ / m ² · h) per unit area of the micropore formation region, and per 1 hole (4b) of the micropore 4a. The flow velocity in the flow direction was 1.0 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 0.19.

  Under the conditions described above, a coarse emulsion that could be visually confirmed was generated, so it was determined that emulsification was poor, and gelation and recovery were not performed.

  As shown in Table 2, according to Examples 4 to 8, the flow rate of n-decane which is a continuous phase is 1.1 to 6.0 m / s, and the flow rate of sodium silicate which is a dispersed phase is 1.0 to Even when the Reynolds number was 2.5 to 768 to 4223, silica particles having a substantially spherical shape, a small D90 / D10, and a uniform particle diameter could be obtained.

  Even under the high Reynolds number conditions as in Examples 6 and 7, silica particles having a uniform particle diameter satisfying D90 / D10 of 1.8 or less could be obtained with high productivity. Further, as in Example 8, even when the flow rate of the dispersed phase was further increased, silica particles having a small D90 / D10 and a uniform particle diameter could be obtained.

  In Reference Example 4, silica particles having a small D90 / D10 and a uniform particle diameter are obtained, but the flow rates of the continuous phase and the dispersed phase are low, the Reynolds number is small, the supply amount of the dispersed phase is small, and the production is performed. Decreased.

  In Comparative Example 2, the emulsion droplets became coarse and poorly emulsified. This is because the flow rate of n-decane, which is a continuous phase, is low, and a sufficient shearing force cannot be obtained on the outlet side of the micropore 4a, so that the sodium silicate injected from the micropore 4a becomes droplets. In addition, it is considered that coarse emulsion droplets were generated by reaching the partition wall in which the micropores 4a were formed and the partition wall facing this partition wall.

<Test of flow path height>
Through the tests of Examples 9 to 10 below, the average particle diameter (D50) and D90 / D10 of silica particles, which are spherical particles, were evaluated with respect to the height of the flow path. The production conditions and evaluation results of the silica particles are shown in Table 3 together with the evaluation results of Example 1 and Example 11 described later.

Example 9
In Example 9, in the emulsification apparatus A, the stainless steel plate 3 obtained by etching one penetration part (3a) having a width of 3.0 mm and a length of 74 mm corresponding to a flow path (microchannel) A W / O emulsion was prepared, gelled, and recovered in the same manner as in Example 1 except for the following points, using an emulsification apparatus A ^* changed to a 400 μm SUS304 sheet. That is, in Example 9, the flow path height in the emulsifying apparatus A used in Example 1 was set to 400 μm. Table 4 shows the setting conditions of the emulsifier A ^* .

At this time, the supply amount of n-decane was 10.7 L / h per flow path, and the flow velocity in the flow direction in the flow path was 2.5 m / s. The experiment was performed at room temperature. At this time, the Reynolds number of the flow of n-decane was calculated from the above equation 2a from the hydrodynamic radius of the flow path: 176 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s 1372. Met. The amount of No. 3 sodium silicate supplied was 3.94 L / h (39.8 m ³ / m ² · ³ ) per unit area of the micropore formation region (9.89 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus A ^* ). h), and the flow velocity in the flow direction per one hole (4b) of the minute hole portion 4a was 0.91 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 2.7.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 28.4 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.48. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

(Example 10)
In Example 10, a stainless steel plate 3 obtained by etching one through hole (3a) having a width of 3.0 mm corresponding to a flow path (microchannel) in the emulsification apparatus A is made of SUS304 having a thickness of 800 μm. Using the emulsifier A ^** changed to a sheet, a W / O emulsion was prepared, gelled, and recovered in the same manner as in Example 1 except for the following points. That is, in Example 10, the height of the flow path was set to 800 μm in the emulsifying apparatus A used in Example 1. Table 4 shows the setting conditions of the emulsifier A ^** .

At this time, the supply amount of n-decane was 21.3 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 2.5 m / s. The experiment was performed at room temperature. At this time, the Reynolds number of the flow of n-decane was calculated from the above formula 2a from the hydrodynamic radius of the flow path: 316 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s 2451. Met. Moreover, the supply amount of No. 3 sodium silicate is 4.03 L / h (40.7 m ³ / m ² ) per unit area of the micropore formation region (9.89 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus A ^** ). H), and the flow velocity in the flow direction per hole (4b) of the microhole portion 4a was 0.93 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the micropores 4a was 2.6.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 39.3 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.46. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

  As shown in Table 3, according to Examples 1, 9 and 10, silica particles having a substantially spherical shape, a small D90 / D10, and a uniform particle diameter can be obtained even if the height of the flow path is changed. It was.

<Circulation number test>
Through the following tests, the average particle diameter (D50) and D90 / D10 of the silica particles, which are spherical particles, were evaluated with respect to the number of circulations of the continuous phase. The production conditions and evaluation results of the silica particles are also shown in Table 3.

(Example 11)
"1. Preparation of dispersed phase and continuous phase"
A dispersed phase and a continuous phase were prepared in the same manner as in Example 1.

"2-1. Production of emulsifying device"
An emulsification apparatus A was produced in the same manner as in Example 1.

“2-2. Test equipment production”
A schematic diagram of a test facility for circulating the continuous phase is shown in FIG.

  In the test facility shown in FIG. 3, the emulsifying device 8 produced in the above “2” is placed so that the flow path is in the horizontal direction, and the emulsion receiving tank 9 is arranged vertically below the emulsion outlet portion 6. The nozzle provided on the side surface of the emulsion receiving tank 9 and the nozzle provided on the side surface of the continuous phase supply tank 11 were connected by a fluororesin tube. A fluororesin tube was inserted to the bottom of the continuous phase supply tank 11 and connected to the emulsifying device 8 via a gear pump. In addition, a dispersed phase supply tank 12 was installed, and a fluororesin tube was also inserted to the vicinity of the bottom surface, and connected to the emulsifying device 8 via a gear pump.

“3. Preparation of emulsion”
8 L of the surfactant-containing n-decane prepared in the above “1” was put into the continuous phase supply tank 11. The supply amount of n-decane was 16.2 L / h per flow channel as in Example 1, and the flow velocity in the flow direction in the flow channel was 2.5 m / s. The amount of No. 3 sodium silicate supplied was 3.99 L / h (40.3 m ³ / m ² · h) per unit area of the micropore formation region (9.89 × 10 ⁻⁵ m ^{2 in the} emulsifying apparatus A). The flow velocity in the flow direction per one hole (4b) of the microhole portion 4a was 0.92 m / s. The experiment was performed at room temperature, and the calculated value of the Reynolds number of the n-decane flow at this time was 1967. The emulsion discharged from the emulsion outlet 6 was stored in an emulsion receiving tank 9 and allowed to stand to cause two-phase separation into an emulsion and n-decane. The supernatant n-decane was sent to the continuous phase supply tank 11 and used again as a continuous phase for emulsification. The emulsion separated in two phases in the emulsion receiving tank 9 was extracted from the emulsion extraction outlet 10 as needed.

  The supply of n-decane and No. 3 sodium silicate was carried out for a total of 12 hours. At this time, n-decane was repeatedly used about 24 times.

"4. Gelation and recovery"
About the emulsion extracted from the emulsion exit part 6, it gelatinized and collect | recovered similarly to the said Example 1. FIG.

“5. Shape confirmation”
When the emulsion after 12 hours was collected and the shape was confirmed after gelation, it was confirmed to be spherical.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 36.5 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.43. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

  As shown in Table 3, from Examples 1 and 11, it was found that there was almost no change in D50 or D90 / D10 even when n-decane as a continuous phase was repeatedly used.

<Small size test of spherical silica particles>
Example 12
In Example 12, the stainless steel plate 3 obtained by etching one through hole (3a) having a width of 3.0 mm corresponding to the flow path (microchannel) in the emulsification apparatus A is made of SUS304 having a thickness of 200 μm. A W / O emulsion was prepared, gelled, and recovered in the same manner as in Example 1 except for the following points, using the emulsification apparatus E that was changed to a sheet. The dispersed phase was prepared by diluting No. 3 sodium silicate with water so that the SiO2 concentration was 21.5% by mass. Further, the stainless steel plate 4 has a micropore 4a at a position where the micropore 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 on a 50 μm thick SUS304 sheet. However, the surface is hydrophobized. The micropore 4a has an area of 2.63 mm × 38.3 mm (1.01 × 10 ⁻⁴ m ² ) in the center of the flow path, and a pore diameter of 7 μm on the outlet side (lower side, that is, the stainless steel plate 3 side). A certain number of circular through-holes are machined at a pitch of 57 μm at a pitch of 57 μm. Table 4 shows the setting conditions of the emulsifier E.

At this time, the supply amount of n-decane was 13.2 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 6.1 m / s. The experiment was performed at room temperature, and at this time, the Reynolds number of the flow of n-decane was calculated from the above formula 2a from the hydrodynamic radius of the flow path: 93.8 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s. It was 1804. Moreover, the supply amount of No. 3 sodium silicate is 2.40 L / h (23.8 m ³ / m ² · h) per unit area of the micropore formation region (1.01 × 10 ⁻⁴ m ^{2 in the} emulsification apparatus E). The flow velocity in the flow direction per one hole (4b) of the microhole portion 4a was 0.55 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 11.1.

  The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume conversion particle diameter (D50) was 10.1 μm, the 90% volume conversion particle diameter (D90) and the 10% volume conversion particle diameter (D10). The ratio (D90 / D10) was 1.66. The pore volume measured by the nitrogen adsorption method was 1.0 cm ³ / g.

<Test for production of high pore volume silica porous sphere>
Through the following tests, the average particle diameter (D50) and D90 / D10 of the silica particles, which are the spherical particles obtained, were evaluated for the production of high pore volume silica porous spheres.

(Example 13)
"1. Preparation of dispersed phase and continuous phase"
The dispersed phase was prepared by mixing No. 3 sodium silicate and an aqueous sodium sulfate solution so that the SiO2 concentration was 10% by mass and the sodium sulfate concentration was 8.5%. The density of No. 3 sodium silicate at this time was 1150 kg / m ³ . The continuous phase was prepared as in Example 1.

"2. Emulsification device F"
In Example 13, emulsification was performed using the emulsifier F. A schematic cross-sectional view of the emulsifying device F is as shown in FIG. Table 4 shows the setting conditions of the emulsifying device F.

  In the emulsification apparatus F, the stainless steel plate 3 is etched by a single piercing part (3a) having a width of 3.0 mm and a length of 74 mm corresponding to a flow path (microchannel) with respect to a SUS304 sheet having a thickness of 600 μm. That is, a flow path 3a having a width of 3.0 mm and a height of 600 μm is formed.

The stainless steel plate 4 has a microhole portion 4a at a position where the microhole portion 4a overlaps the central portion of the flow path 3a when the stainless steel plate 4 is overlapped with the stainless steel plate 3 with respect to a sheet made of SUS304 having a thickness of 50 μm. The surface is hydrophobized. The microhole portion 4a has an area of 2.61 mm × 37.9 mm (9.89 × 10 ⁻⁵ m ² ) in the center of the flow path and a hole diameter on the outlet side (lower side, that is, the stainless steel plate 3 side) of 12.2. 10260 circular through-hole portions 4b of 7 μm are processed at a pitch of 100 μm. In addition, the stainless steel plates 3 and 4 were subjected to water repellent treatment in the same manner as the emulsification apparatus A.

  The stainless steel plate 3 and the stainless steel plate 4 are overlapped as shown in FIG. 1, and each of the acrylic member 2 for forming the dispersed phase flow path having the dispersed phase inlet portion 7, the continuous phase inlet portion 5 and the emulsion outlet portion 6 is provided. The emulsification apparatus F was produced by sandwiching with an acrylic member 1 having a flow path. The four sides of the emulsifier F were clamped and fixed with a uniform force, and it was confirmed that there was no leakage by supplying water in advance.

“3. Preparation of emulsion”
The emulsifying device F produced in the above “2” is used so that the flow path is in the horizontal direction, and n-decane in which the surfactant prepared in the above “1” is dissolved from the continuous phase inlet portion 5 is used. By supplying the No. 3 sodium silicate prepared in the above “1” from the dispersed phase inlet 7 through the micropores 4a, the No. 3 sodium silicate is dispersed in n-decane in which the surfactant is dissolved. An O-type emulsion was continuously produced.

At this time, the supply amount of n-decane was 14.8 L / h per flow channel, and the flow velocity in the flow direction in the flow channel was 2.3 m / s. The experiment was performed at room temperature. At this time, the Reynolds number of the flow of n-decane was calculated from the above formula 2a from the hydrodynamic radius of the flow path: 250 μm and the viscosity: 9.28 × 10 ⁻⁴ Pa · s, 1797. Met. Moreover, the supply amount of No. 3 sodium silicate is 5.01 L / h (50.6 m ³ / m ² · h per unit area of the micropore formation region (9.89 × 10 ⁻⁵ m ^{2 in the} emulsification apparatus F)). The flow velocity in the flow direction per one hole (4b) of the microhole portion 4a was 1.1 m / s.

  At this time, the ratio of the flow rate in the flow direction of n-decane to the flow rate in the flow direction of the sodium silicate micropores 4a supplied from the microholes 4a was 2.1.

"4. Gelation and aging"
After collecting 300 ml of the W / O type emulsion prepared in “3” above, the solution temperature is cooled to 10 ° C., and carbon dioxide gas having a concentration of 100% by mass is blown in at a supply rate of 100 mL / min for 25 minutes while stirring. Gelation was performed. To the produced silica hydrogel, 200 mL of water was added and allowed to stand for 10 minutes, and then two phases were separated due to the difference in specific gravity to obtain an aqueous slurry (aqueous phase) of silica hydrogel. The obtained silica hydrogel water slurry was filtered and washed with 2 L of ion-exchanged water, and 1N aqueous sodium hydroxide solution was added to adjust the pH to 9. Then, as a ripening step, the mixture was heated to 93 ° C. and stirred for 1 hour.

"5. Cleaning and recovery"
0.1 predetermined sulfuric acid was added to the water slurry aged in the above “4” to adjust the pH to 2. Next, the water slurry was filtered, washed with 2 L of ion exchange water, and finally ion exchange water was added to make a 10% slurry. This silica slurry was dried at 200 ° C. with a spray dryer (Nibuchi Mini Spray Dryer B290) to obtain spherical silica powder.

“6. Shape confirmation”
The obtained porous silica spherical body was confirmed to be almost spherical from a scanning electron micrograph.

Moreover, when this silica porous spherical body was measured with a Coulter counter, the 50% volume equivalent particle diameter (D50) was 27.4 μm, the 90% volume equivalent particle diameter (D90) and the 10% volume equivalent particle diameter (D10). The ratio (D90 / D10) was 1.37. The pore volume measured by the nitrogen adsorption method was 2.6 cm ³ / g.

Table 4 summarizes the details of the emulsifiers A to F, A ^* , and A ^** used in the above test.

The method for producing spherical particles according to the present invention can provide spherical particles having a narrow particle size distribution with high productivity and can be used in various fields. For example, toner, heat insulating material, food additive, medical diagnostic agent, paint filler, cosmetic filler, resin film filler, liquid crystal spacer, chromatography filler, catalyst, catalyst carrier, resin filler, adsorbent It can be used as a desiccant and the like.
The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2012-286913 filed on Dec. 28, 2012 are cited here as disclosure of the specification of the present invention. Incorporated.

DESCRIPTION OF SYMBOLS 1 Acrylic resin member 2 Acrylic resin member 3 Stainless steel plate 3a Channel 4 Stainless steel plate 4a Micro hole portion 4b Through hole portion 5 Continuous phase inlet portion 6 Emulsion outlet portion 7 Dispersed phase inlet portion 8 Emulsifying device 9 Emulsion receiving tank 10 Emulsion extraction Outlet part 11 Continuous phase supply tank 12 Dispersed phase supply tank

Claims (14)

The compartmentalized flow path in a continuous phase liquid flowing at a flow rate not less than than 10 m / s to 2.0 m / s with a septum, through the minute holes formed in the partition wall, the dispersed phase liquid containing spherical particle precursor 1 Extruding at a flow rate of 0.1 to 5 m / s per pore to produce an emulsion,
A method for producing spherical particles, comprising: solidifying emulsion droplets containing the spherical particle precursor to form spherical particles; and collecting the spherical particles.   The manufacturing method of the spherical particle of Claim 1 whose height of the said flow path is 200 micrometers-1 mm.   The manufacturing method of the spherical particle of Claim 1 or 2 whose Reynolds number of the continuous phase liquid which flows in the said flow path is 500-10000.   The method for producing spherical particles according to any one of claims 1 to 3, wherein the flow path has a length of 1 to 500 mm.   The manufacturing method of the spherical particle of any one of Claim 1 to 4 whose number of the said micropore part opened to the said flow path is 1000 or more.   The method for producing spherical particles according to any one of claims 1 to 5, wherein a ratio of a flow velocity in the flow direction of the continuous phase liquid to a flow velocity in the flow direction of the dispersed phase liquid is 0.1 to 100. The method for producing spherical particles according to any one of claims 1 to 6 , wherein the spherical particles have a D90 / D10 of 1.75 or less. The manufacturing method of the spherical particle of any one of Claim 1 to 7 whose average particle diameter D50 of the said spherical particle is 10-100 micrometers. The method for producing spherical particles according to any one of claims 1 to 8 , wherein the dispersed phase liquid is an aqueous liquid containing an inorganic compound, and the continuous phase liquid is an organic liquid. The manufacturing method of the spherical particle of any one of Claim 1 to 9 in which the said continuous phase liquid contains surfactant. The method for producing spherical particles according to any one of claims 1 to 10 , wherein the spherical particle precursor is an alkali metal silicate. A water-insoluble organic liquid containing a surfactant is used as the continuous phase liquid, and an aqueous solution of an alkali metal silicate is used as the dispersed phase liquid to produce an emulsion in which the aqueous alkali metal silicate solution is dispersed. Item 12. The method for producing spherical particles according to any one of Items 1 to 11 . The method for producing spherical particles according to claim 12 , wherein an emulsion droplet comprising an aqueous solution of an alkali metal silicate is gelled by adding an acid to the emulsion to form a spherical silica hydrogel. The method for producing spherical particles according to claim 13 , wherein the silica hydrogel is recovered and dried to obtain spherical silica particles.

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