JP4997395B2 - Hollow particles having unique shell and method for producing the same - Google Patents

Description

  The present invention relates to hollow particles having a unique structure and a method for producing the same.

  A spherical particle material having a large hollow portion inside the material is a material with high possibility of application because it can contain various compounds and materials including air inside the material. As a microcapsule material made of an inorganic material, for example, synthesis of microcapsules made of silica has been reported in Patent Document 1 and Patent Document 2. In addition, a method for producing carbonate microcapsules is also known (Patent Documents 3, 4, etc.). These are inorganic microcapsules synthesized by an interfacial reaction method using a W / O / W emulsion, but since a hollow structure is automatically formed during the synthesis, it is particularly advantageous in the synthesis of compound-encapsulated microcapsules. have. When these microcapsules are synthesized from a solution, if various compounds that do not dissolve in the aqueous phase are added in advance to the inner aqueous phase of the W / O / W emulsion, these powders are directly encapsulated in the microcapsules. It is also possible. As a method of encapsulating the compound in the microcapsule, there is a method of filling the compound through pores existing in the shell of the finished microcapsule. In the above method, particles larger than the pores in the shell are encapsulated. You can also Examples of powdery substances filled by this method include inorganic powder (Patent Document 5), colorant (Patent Document 6), oil droplets (Patent Document 7), immobilized sake yeast (Patent Document 8), and immobilization. There are microorganisms (Patent Document 9), deodorizers (Patent Document 10, Patent Document 11), and the like. On the other hand, it has been reported that even when a biological macromolecule soluble in the inner aqueous phase of the W / O / W emulsion is added, the biological macromolecule can be encapsulated in the microcapsule (Patent Document 12).

  The synthesis of inorganic microcapsules is rapid by adding a W / O emulsion to another aqueous phase (outer aqueous phase) to form a W / O / W emulsion and mixing the inner aqueous phase with the outer aqueous phase. The key point is to form an inorganic precipitate. The encapsulation of the compound means that when a microcapsule is formed by the reaction between the inner aqueous phase and the outer aqueous phase, the compound added to the inner aqueous phase is left inside and filled. However, it is considered that a compound that dissolves easily in water and has a high diffusion rate in water diffuses into the outer water phase before inorganic precipitation of the capsule shell, and is hardly encapsulated.

  Silica particles have the property of essentially forming micropores (diameter 2 nm or less) and mesopores (diameter 2 to 60 nm), and therefore many of them have these micropores and mesopores. However, it is not always easy to synthesize silica particles having macropores (diameter 60 nm or more), particularly macropores of 100 nm or more. Further, there are almost no examples of silica particles having a spherical particle shape and having a large cavity inside (microcapsule) and having such macropores in the capsule shell.

The most representative example of the synthesis of hollow silica particles is the deposition of silica on oil droplets and organic polymer particles that form emulsions and fine particles in water to create a core (core) / shell structure material. In this method, oil droplets, polymer, etc. are removed by baking or solvent extraction. There is a report that a part of the shell is ruptured during the process of removing the core part to form a hollow body having one large hole (macropore) (for example, Patent Documents 13, 14, and 15; G. Zhang et al.). al., J. Colloid Interface Sci. vol.263, p.467-472 (2003); G. Fornasieri et al., Adv. Mater. vol.16, p.1094-1097 (2004)). In addition, after the polymerizable monomer is subjected to aqueous suspension polymerization, the polyalkoxysiloxane oligomer is condensed and the particles coated with silica so as to expose a part of the surface of the polymer particles are baked. There is a report that a hole of a size can be synthesized (Patent Document 16). On the other hand, a material in which a large number of macropores are formed in non-hollow silica spherical particles has also been reported (for example, F. Iskandar et al., Nano Lett., Vol.1, p.231-234 ( 2001); A. Kulak et al., Chem. Commun. P.576-577 (2004)). However, there is no known material in which spherical hollow silica particles are formed with innumerable similar macropores in the shell portion.
JP 63-270306 JP 61-227913 Patent 1184016 Patent 1049606 JP 53-22530 JP 61-47410 JP 61-57236 JP 62-44185 JP 62-158485 JP 62-212315 JP-A 62-212316 Japanese Patent Application 2005-200390 JP 08-091821 JP 07-257919 JP 11-029318 JP2004-307332

  The present invention provides a technique for forming a plurality of macropores in the shell of silica and water-insoluble silicate hollow particles, and a technique relating to such hollow particles.

  From the above viewpoint, in the hollow particle synthesis process, a water-soluble compound for pore formation is added to the inner aqueous phase that is the aqueous phase of the W / O emulsion, and the silica in the W / O / W emulsion and the water-insoluble silicate During the formation process, the water-soluble compound for macropore formation is diffused from the inner aqueous phase to the outer aqueous phase, and pores are formed in the formed silica and water-insoluble silicate by the diffused water-soluble compound for pore formation. Thus, the present inventors have succeeded in producing silica having shells having macropores and hollow particles of water-insoluble silicate, leading to the present invention.

  The present invention provides the following hollow particles and a method for producing the same.

  1. Hollow particles composed of a silicon-based shell having a plurality of macropores.

  2. Item 2. The hollow particles according to Item 1, wherein the shell is composed of silica or alkaline earth metal silicate.

  3. Item 2. The hollow particles according to Item 1, wherein the macropore size is 60 nm to 30 µm.

  4). A plurality of macropores, characterized in that a precipitant aqueous solution is allowed to act on a W / O emulsion in which first water phase particles containing a water-soluble silicate and a water-soluble compound for forming macropores are dispersed in an oil phase. Hollow particles composed of a silicon shell.

5. The precipitant is ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium hydrogen sulfate, ammonium bromide, ammonium iodide, ammonium hydrogen carbonate, ammonium carbonate, ammonium acetate, ammonium formate, ammonium tartrate, ammonium citrate, alkali metal hydrogen carbonate, Item 5. The method according to Item 4, wherein the method is at least one selected from the group consisting of carbonates and sesquicarbonates, and the silicon-based shell is silica.

  6). Item 4. The precipitant is at least one selected from the group consisting of alkaline earth metal halides, sulfates, nitrates, formates and acetates, and the silicon-based shell is an alkaline earth metal salt. The method described in 1.

  Since the hollow particles of this patent have a plurality of macropores in the capsule shell pores, they can enclose macrobiomolecules, cells, viruses, etc., and can be stored for a long period of time. The internal material can be selectively released by chemical means such as high pH or fluorination.

A conceptual diagram of the present invention is shown in FIG.
Silica having macropores in the shell and water-insoluble silicate hollow particles can be obtained by improving the existing silica / hollow particle synthesis. Examples of the water-insoluble silicate constituting the shell include alkaline earth metal silicates such as calcium silicate, magnesium silicate, strontium silicate, and barium silicate. That is, a water-soluble compound is dissolved in an aqueous phase that is an aqueous solution of sodium silicate (preferably water glass) that is a raw material of hollow particles having a silicon-based shell of either silica or water-insoluble silicate (FIG. 2). Aqueous phase 1). When the additive dissolved in the aqueous phase 1 is appropriate, a plurality of macropores can be formed in the shell composed of either the silica to be formed or the water-insoluble silicate. The water-soluble compound for forming macropores suitable for such purposes is not particularly limited, but includes water-soluble organic polymers or salts thereof, organic polymers capable of forming alkali salts under alkaline conditions, or neutral inorganic salts. I can give you. Although it does not specifically limit as neutral inorganic salt, For example, sodium chloride, sodium bromide, potassium chloride, potassium bromide etc. are mentioned.

  The water-soluble silicate such as sodium silicate to be used is not particularly limited, but commercially available JIS standard No. 1 to No. 3 water glass, No. 4 water glass, sodium metasilicate and the like may be used. Further, the concentration of the water-soluble silicate in the aqueous phase 1 is not particularly limited, but is preferably 0.5 to 6M, particularly 2 to 5M. The kind and density | concentration of the precipitant used for the water phase 2 will not be specifically limited if the precipitation of a silica and a water-insoluble silicate can produce | generate. As the type of precipitant, when the shell is made of silica, ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium hydrogen sulfate, ammonium bromide, ammonium iodide, ammonium hydrogen carbonate, ammonium carbonate, ammonium acetate, ammonium formate, tartaric acid Ammonium, ammonium citrate, alkali metal hydrogen carbonate, carbonate, sesqui carbonate, etc. are mentioned, preferably ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium bromide, ammonium iodide, ammonium hydrogen carbonate, sodium hydrogen carbonate, carbonic acid Examples thereof include potassium hydrogen. When the shell is composed of a water-insoluble silicate, calcium, magnesium, strontium, barium halide, sulfate, nitric acid, formate, acetate, or the like may be used as a precipitant. The absolute amount of the precipitating agent is required to be greater than the number of moles of silicon in the water-soluble silicate, and usually 2 to 5 times the number of moles of silicon is preferably used. The concentration is preferably 1 to 5M, particularly preferably 1.5 to 3M.

The salt of the organic polymer that is a water-soluble compound for forming macropores is not particularly limited as long as it does not become acidic when dissolved in water, but an alkali metal salt of polyacrylic acid, an alkali metal salt of polymethacrylic acid, polystyrene Examples thereof include alkali metal salts of sulfonic acid. This includes a high molecular compound which becomes an alkali salt under alkaline conditions and does not become acidic in the whole solution, and examples thereof include glycogen and polyvinyl alcohol. The concentration of these organic polymers or organic polymer salts is not particularly limited as long as silica precipitates are not generated from water-soluble silicate aqueous solutions such as water glass by adding additives, but good macropores are formed in the shells of hollow particles. To achieve this, a concentration of polymer salt above a certain amount is desirable. Although depending on the polymer salt used, 50 g / L to 180 g / L is good, and 80 g / L to 120 g / L is particularly preferable. Although the average molecular weight of the organic polymer to be used is not particularly limited, it is preferably 3000 to 5,000,000. An appropriate average molecular weight depends on the polymer, but in the case of polyacrylate and polymethacrylate, about 5,000 to 15,000 is particularly preferable. In the case of polystyrene sulfonate, 500,000 to 3,000,000 are preferable. The metal to be a salt is not particularly limited as long as it can maintain the water solubility of the polymer salt, and examples thereof include alkali metals and ammonium salts.

  Examples of neutral inorganic salts that are water-soluble compounds for forming macropores include halogenated salts of alkali metal salts such as sodium chloride, potassium chloride, sodium bromide, and lithium chloride. The amount of the salt added to the aqueous phase 1 is not particularly limited, but 50 g / L to 180 g / L is preferable to form macropores in the shell of the microcapsules of silica and water-insoluble silicate. / L to 120 g / L is particularly preferable.

  At this time, the macropores formed in the silica and the water-insoluble silicate hollow particles depend not only on the type and concentration of the additive of the aqueous phase 1 but also on the components of the oil phase. The organic solvent to be used is not particularly limited as long as it is hardly mixed with water and hardly reacts with alkali, but hydrocarbons are preferable, and paraffinic hydrocarbons such as hexane, octane and decane are particularly preferable. The surfactant added to the oil phase is not particularly limited as long as it has an effect of stabilizing the W / O emulsion, but sorbitan fatty acid esters are preferable, and Tween and Spans are particularly preferable. These can be used alone, but a mixture of both may be used. The rotation speed of the homogenizer at the time of forming the emulsion is not particularly limited, but the rotation speed is preferably 5000 or more. Further, the time for forming the emulsion by the homogenizer is not particularly limited, but may be about 1 to 3 minutes. Further, the stirring time after addition to the aqueous phase 2 is not particularly limited, but is preferably about 10 minutes to 5 hours, and particularly preferably about 30 minutes to 3 hours.

  The pore size of the macropores is about 60 nm to 30 μm, preferably about 100 nm to 25 μm, more preferably about 300 nm to 20 μm, and still more preferably about 500 nm to 10 μm.

  The size of the hollow particles is, for example, about 0.2 to 100 μm, preferably about 0.5 to 50 μm, more preferably about 1 to 20 μm. The particle size of the hollow particles can be controlled by the particle size of the W / O emulsion (emulsion production conditions).

  The number of macropores per hollow particle is 2 or more, preferably about 3 to 100, more preferably about 5 to 50, and still more preferably about 5 to 30.

  The form and pore structure of the obtained shell silica having macropores and water-insoluble silicate microcapsules can be confirmed by an optical microscope, an electron microscope, or an adsorption isotherm of nitrogen. The size of the macropores obtained depends on the type and concentration of the polymer used, the type of surfactant and the precipitating agent, and varies from several hundred nm to several tens to several tens of microns in the finished silica and water-insoluble silicate hollow particles. It is possible to fill a compound of the size of If the compound is larger than the macropores of the shell, it can be directly encapsulated and enclosed in the hollow particle microcapsules regardless of whether it is dissolved or insoluble in the aqueous phase 1.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.
Example 1: Synthesis of Macroporous Shell Silica Microcapsules-1
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( A solution of Tween80 (1.01 g: the number of moles is unknown for the mixture) and Span80 (0.50 g: the number of moles is unknown for the mixture) dissolved in n-hexane to a total volume of 72 ml (FIG. 1) Oil phase) and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium bicarbonate (39.8
g, 504 mmol) was dissolved in water to a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

The optical microscopic image and electron microscopic image of the obtained macroporous silica-microcapsule are shown in FIGS. In the optical microscopic image of a normal silica microcapsule in which only water glass is dissolved without adding an additive to the aqueous phase 1 (right side of FIG. 2), the inside of the capsule looks bright and light, but this macroporous silica / The microcapsule (left in FIG. 2) is characterized in that one particle looks like a black dot. Moreover, it was confirmed from an electron microscope image that this particle has a hollow sphere. Furthermore, it was also found that pores having such a size as to be observed with an electron microscope were formed in the shell portion of the hollow microcapsule. The size of the pore was also found to be about 3 to 500 nm from an electron microscope image.
Example 2: Synthesis of Macroporous Shell Silica Microcapsule-2
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( A solution of Tween80 (1.01 g: the number of moles is unknown for the mixture) and Span80 (0.50 g: the number of moles is unknown for the mixture) dissolved in n-hexane to a total volume of 72 ml (FIG. 1) Oil phase) and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium chloride (27.0 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

FIG. 4 shows an electron microscope image of the obtained macroporous shell silica microcapsule. From this electron microscope image, it was also confirmed to be a hollow sphere as in Example 1. It was also found from the electron microscope image that the pore size of the shell portion of the hollow microcapsule was about 1 to 3 μm.
Example 3: Synthesis of macroporous silica microcapsules-3
Water glass No. 3 (29.88 g, silicon content 144 mmol) and poly-p-styrene sulfonate sodium aqueous solution (4 g, polymer 1 g; manufactured by Aldrich: Mw to 1,000,000; 25% aqueous solution) were dissolved, and the total volume was dissolved. Tween 80 (1.01 g: the number of moles is unknown about the mixture) and Span 80 (0.50 g: the number of moles are unknown about the mixture) were dissolved in n-hexane in an aqueous solution of 36 ml of water (aqueous phase 1 in FIG. 1), and the total volume was 72 ml. The resulting solution (oil phase in FIG. 1) is mixed and emulsified using a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium hydrogen carbonate (39.8 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous silica microcapsule is shown in FIG. From this electron microscope image, it was also confirmed to be a hollow sphere as in Example 1. Moreover, a hollow part was confirmed inside the shell of the hollow microcapsule. The size of the hollow part in the shell was also found to be about several hundred nm to 1 μm from an electron microscope image.
Example 4 Synthesis of Macroporous Shell Silica Microcapsules-4
Water glass No. 3 (29.88 g, silicon content 144 mmol) and poly-p-styrene sulfonate sodium aqueous solution (4 g, polymer 1 g; manufactured by Aldrich: Mw to 1,000,000; 25% aqueous solution) were dissolved, and the total volume was dissolved. Tween 80 (1.01 g: the number of moles is unknown about the mixture) and Span 80 (0.50 g: the number of moles are unknown about the mixture) were dissolved in n-hexane in an aqueous solution of 36 ml of water (aqueous phase 1 in FIG. 1), and the total volume was 72 ml. The resulting solution (oil phase in FIG. 1) is mixed and emulsified using a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium chloride (27.0 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous silica microcapsule is shown in FIG. From the electron micrograph, it was also confirmed to be a hollow sphere as in Example 1. It was also found that macropores of several hundred nm to several μm were formed inside the shell of the hollow microcapsule or the entire shell.
Example 5 Synthesis of Macroporous Shell Silica Microcapsules-5
Water glass No. 3 (29.88 g, silicon content: 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; Aldrich Mw-9500; 30% aqueous solution) were dissolved to make a total volume of 36 ml (Fig. 1) Aqueous phase 1) was prepared by dissolving Tween80 (1.01 g: the number of moles is unknown for the mixture) and Span80 (0.50 g: the number of moles is unknown for the mixture) in n-hexane to a total volume of 72 ml (FIG. 1). Oil phase) and emulsified with a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium bicarbonate (39.8 g
504 mmol) was dissolved in water to a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron micrograph, it was also confirmed that it was a hollow sphere like Example 1, but it was also found that macropores of about several hundred nm to several μm were formed in the shell of the hollow microcapsule.
Example 6 Synthesis of Macroporous Shell Silica Microcapsules-6
Water glass No. 3 (29.88 g, silicon content 144 mmol) and sodium polyacrylate aqueous solution (8.89 g, polymer 4 g; Aldrich Mw to 8000; 45% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml (Fig. 1) Aqueous phase 1) was prepared by dissolving Tween80 (1.01 g: the number of moles is unknown for the mixture) and Span80 (0.50 g: the number of moles is unknown for the mixture) in n-hexane to a total volume of 72 ml (FIG. 1). Oil phase) and emulsified with a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium hydrogen carbonate (39.8 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron microscopic image, it was confirmed that it was a hollow sphere as in Example 1, but it was also found that a macropore of about several hundred nm was formed in the shell of the hollow microcapsule.
Example 7 Synthesis of Macroporous Shell Silica Microcapsules-7
Water glass 3 (29.88 g, silicon content 144 mmol) and glycogen 4 g were dissolved in an aqueous solution (aqueous phase 1 in FIG. 1) to a total volume of 36 ml. 0.50 g: the number of moles is unknown for the mixture) is dissolved in n-hexane and mixed with a solution (oil phase in FIG. 1) having a total volume of 72 ml, and emulsified with a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium hydrogen carbonate (39.8 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron micrograph, it was confirmed that it was a hollow sphere like Example 1, and it was also found that macropores of several hundred nm to several μm were formed in the shell of the hollow microcapsule.
Example 8 Synthesis of Macroporous Shell Silica Microcapsules-8
Water glass No. 3 (29.88 g, silicon content 144 mmol) and glycogen 4 g were dissolved in an aqueous solution (water phase 1 in FIG. 1) to a total volume of 36 ml, and Tween 80 (1.01 g: the number of moles is unknown for the mixture) and Span 80 ( 0.50 g: the number of moles is unknown for the mixture) is dissolved in n-hexane and mixed with a solution (oil phase in FIG. 1) having a total volume of 72 ml, and emulsified with a homogenizer at a rotational speed of about 8300. After this emulsification treatment for 1 minute, ammonium chloride (27.0 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). Stir for 2 hours (rotation speed:
After about 250 revolutions), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron micrograph, it was confirmed that it was a hollow sphere like Example 1, and it was also found that a macropore of about several hundred nm was formed in the shell of the hollow microcapsule.
Example 9 Synthesis of Macroporous Shell Silica Microcapsule-9
Water glass 3 (29.88 g, silicon content 144 mmol) and sodium chloride 6 g were dissolved in an aqueous solution (aqueous phase 1 in FIG. 1) to a total volume of 36 ml, and Tween 80 (1.01 g: the number of moles is unknown for the mixture) and Span 80 (0.50 g: the number of moles is unknown for the mixture) is dissolved in n-hexane and mixed with a solution (oil phase in FIG. 1) having a total volume of 72 ml, and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium chloride (27.0 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron micrograph, it was also confirmed that it was a hollow sphere like Example 1, and the shell of the hollow microcapsule was composed of fine particles of about several hundred nm, and macropores were formed between the fine particles. I understand.
Example 10 Synthesis of Macroporous Shell Silica Microcapsules-1
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( In the aqueous phase 1) in Fig. 1, Span80 (1.51 g: the number of moles is unknown for the mixture) is dissolved in n-hexane and mixed to a total volume of 72 ml (oil phase in Fig. 1), and a homogenizer is used. And emulsify at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium hydrogen carbonate (39.8 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron micrograph, it was confirmed that the particles had hollow spheres, and the shell of the hollow microcapsules was composed of fine particles of about several hundred nm, and it was also found that macropores were formed between the fine particles. It was.
Example 11 Synthesis of Macroporous Shell Microcapsules-11
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( In the aqueous phase 1) of FIG. 1, Tween80 (0.50 g: the number of moles is unknown for the mixture) and Span80 (1.01 g: the number of moles is unknown for the mixture) were dissolved in n-hexane to give a total volume of 72 ml (FIG. 1). Oil phase) and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium bicarbonate (39.8
g, 504 mmol) was dissolved in water to a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

An electron microscopic image of the obtained macroporous shell silica microcapsule is shown in FIG. From the electron microscope image, it was confirmed that the particles had hollow spheres, and it was also found that the hollow microcapsule shells were formed with macropores of several hundred nm to several μm.
Example 12 Synthesis of Macroporous Shell Microcapsules-12
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( In the aqueous phase 1) of FIG. 1, Tween80 (0.50 g: the number of moles is unknown for the mixture) and Span80 (1.01 g: the number of moles is unknown for the mixture) were dissolved in n-hexane to give a total volume of 72 ml (FIG. 1). Oil phase) and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, ammonium chloride (27.0 g, 504 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

FIG. 14 shows an electron microscopic image of the obtained macroporous shell silica microcapsule. From the electron microscope image, it was confirmed that the particles had hollow spheres, the shell of the hollow microcapsule was composed of fine particles of about 1 to 2 μm, and macropores of about several μm were formed between the fine particles. I also found out.
Example 13 Synthesis of Macroporous Shell Silica Microcapsules-13
Water glass 3 (29.88 g, silicon content 144 mmol) and poly (sodium methacrylate) aqueous solution (13.3 g, polymer 4 g; manufactured by Aldrich: Mw-6500; 30% aqueous solution) were dissolved in an aqueous solution having a total volume of 36 ml ( A solution of Tween80 (1.01 g: the number of moles is unknown for the mixture) and Span80 (0.50 g: the number of moles is unknown for the mixture) dissolved in n-hexane to a total volume of 72 ml (FIG. 1) Oil phase) and emulsified with a homogenizer at about 8300 revolutions. After this emulsification treatment for 1 minute, calcium chloride dihydrate (59.3 g, 403 mmol) was dissolved in water and added to a solution having a total volume of 250 ml (aqueous phase 2 in FIG. 2). After stirring for 2 hours (rotation speed: about 250 rotations), a precipitate formed by filtration was obtained.

  An electron microscopic image of the obtained macroporous shell calcium silicate microcapsule is shown in FIG. From this electron microscope image, it was also confirmed to be a hollow sphere as in Example 1. It was also found from the electron microscope image that the pore size of the shell portion of the hollow microcapsule was about 3 to 6 μm.

Possible application examples Various applications of the materials newly prepared and found in this patent are envisaged. For example, the following applications are conceivable.

  Hollow silica particles are expected to be used in fields such as the semiconductor industry, medical products industry, advanced materials industry, and environmental industry, such as liquid crystal display spacers, ceramic raw materials, chromatographic fillers, optical materials, and precision abrasives. Furthermore, it can be expected that it is suitable for light-weight furnace material, sheath material or heat insulating material because of its high porosity. Furthermore, porous hollow silica particles are often used as an adsorbing / separating agent for oils and fats, organic solvents, and the like, but porous silica particles having a high porosity are required to increase the adsorption capacity. In particular, it is expected that when the pores of the shell portion become macropores, the adsorption performance of highly viscous polymer oils and the like is improved.

  Furthermore, application to drug delivery systems and gene delivery systems is also promising by filling hollow particles with large-sized proteins, cells, nucleic acids and the like. Application to long-term storage of unstable biomaterials by enclosing huge biomaterials and bioreactors encapsulating enzyme proteins are also envisaged.

Conceptual diagram of silica and water-insoluble silicate hollow particle synthesis with macropores in capsule shell Optical microscopic images (1000x) of macroporous silica microcapsules (left) and normal silica microcapsules (right) Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous silica microcapsules Electron microscope image of macroporous calcium silicate microcapsules

Claims (1)

The macro pores having a pore diameter of 60 nm to 1 0 .mu.m to 5 to 100 Yes in part of the silica mosquito shell, wherein the particle size is 0.2～100Myuemu, hollow particles.

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