JP2001038193A - Production of composite silica microcapsule, and method for controlling immobilization and slow releasing action of core substance of composite silica microcapsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for producing a composite silica microcapsule encapsulating a core substance such as an org. compd. or an inorg. compd. SOLUTION: A surfactant and a mixed soln. contg. a surfactant and the core substance and an assistant such as catalyst or surfactant, as required, previously added to water are added as a dispersed phase to a continuous phase obtained by incorporating tetraalkoxysilane as a reactant and an assistant such as catalyst added, as required, into a low-polarity org. solvent forming an interface with water to increase the mole ratio of water to surfactant, and the mixture is agitated to form a water-in-oil emulsion. Further, tetraalkoxysilane is hydrolyzed and polycondensed with the water-in-oil emulsion solubilizing water as a reaction field while adjusting the agitation to synthesize a silica microcapsule. Consequently, the core is encapsulated in the peripheral shell of the microcapsule and/or in the hollow part at the central part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applicable to various fields such as semiconductor industry, medical products industry, advanced materials industry, environmental analysis industry such as ceramic raw materials, chromatography fillers, sensors, catalysts, and diagnostic carriers. The present invention relates to a method for producing a composite silica microcapsule in which a core material such as an organic compound or an inorganic compound is encapsulated in a micron-sized silica microcapsule expected to be used.

[0002]

2. Description of the Related Art Generally, microcapsuls are used.
e) means that the diameter is from several μm to several hundred μm and the shell thickness is 1 μm.
A micro-sized spherical container of about μm that can contain a liquid or solid inside, and has a function of protecting the contained substance from the external environment (eg, pressure-sensitive copying paper, pressure-sensitive adhesive), It has been practically used in products with the function of releasing encapsulated substances to the external environment (for example, sustained-release medicines and sustained-release pesticides), etc., in which multiple materials are compounded in microcapsules. As a result, more applications are possible, and therefore, it is required to establish a composite technology for microcapsules.

[0003] As typical methods for producing silica microcapsules which have been reported so far, phase separation, in-liquid drying, and the like.
Many reports have been made, such as a spray drying method, an interfacial polymerization method, and an in-situ method. Furthermore, when silica microcapsules are composited, the mainstream production method is to impregnate a solution in which a core substance is dissolved after the particles are produced, and then composite.

Several methods for preparing hollow spherical silica particles have been reported. As a first specific example, Tween-80, a nonionic surfactant, and Span-60 are mixed in a ratio of 2: 1. An aqueous solution of sodium silicate was added to a benzene solution to prepare a W / O emulsion, and an aqueous solution of an ammonium salt was injected into the emulsion to prepare spherical silica particles (Yoshiko Nakahara et al., Coloring Material, 61.488 (1988)). .

As a second specific example, N-lauroyl-L-glutamic acid-α, γ-di-n-Non-aqueous gelling agent is used.
Butylamide (LGBA) with tetraethoxysilane and n
-Aqueous ammonia (pH 13.2) (5 μl) was added dropwise to a four-component mixture of decane and methanol or ethanol using a microsyringe, and the solution was allowed to stand. A method of producing a porous hollow silica capsule having a diameter of about 1.5 mm by forming a silica wall film by a polymerization reaction and removing organic substances on the capsule surface by heat treatment (burning out) (Abe Masahiko et al.
Color materials, 68.542 (1995)).

As a third specific example, the continuous phase is an aqueous hydrochloric acid solution, tetraalkoxysilane and mesitylene (C ₆ H ₃ (CH ₃ ) ₃ ) are mixed in the dispersed phase, and the cationic n-hexaamine is added to the surfactant. A method for producing spherical silica particles having a hollow structure by forming an oil-in-water (oil-in-water) emulsion using decyltrimethylammonium bromide (CTAB) and subjecting it to hydrolysis and polycondensation at the oil / water interface (Shact, S. et al, Science, 273, 768 (1996)).

However, just because silica hollow particles can be prepared in any case, a micron-sized composite silica microcapsule containing a material different from silica inside the hollow of the silica microcapsule can be realized in a one-step reaction. It was not reported. In particular, since the second manufacturing method has a heat treatment (burnout) step, when the core material contained is an organic substance, it is often thermally decomposed, and it is difficult to form a practical composite.

[0008]

SUMMARY OF THE INVENTION The present inventors have studied in the past that water solubilized water contained in a water or water-in-oil emulsion (W / O type) in which an aqueous solution was solubilized was converted into tetraalkoxysilane. A production method capable of more easily and efficiently preparing micron-sized spherical silica particles by using a reaction field for hydrolysis and polycondensation of
Micron-sized spherical silica particles having a hollow structure prepared by this method were developed (Japanese Patent Application No. 10-16723).
issue). Then, the present inventors applied the previously developed manufacturing method and aimed to prepare a composite silica microcapsule in which a material different from silica was encapsulated as a core material inside a micron-sized silica microcapsule.

[0009]

As means for solving the above-mentioned problems, first to sixth inventions to be patented are described.
The invention is an invention of a method for producing the composite silica microcapsule, and the seventh invention to the eighth invention for which a patent is sought are the immobilization and sustained release of a core substance contained in the composite silica microcapsule. Is an invention of a control method.

The first invention to be patented is that a low-polarity organic solvent which forms an interface with water contains tetraalkoxysilane as a reactant and an auxiliary agent such as a catalyst optionally added. The continuous phase consists of a surfactant,
A mixed solution containing an auxiliary agent such as a catalyst or a surfactant previously added to water as a core substance as needed is added as a dispersed phase, and adjusted so that the molar concentration ratio of the water and the surfactant is increased. A water-in-oil emulsion is formed while stirring, and while the stirring operation is adjusted, the hydrolysis and polycondensation reaction of tetraalkoxysilane is performed using the solubilized water of the water-in-oil emulsion as a reaction field to produce silica microcapsules. Is synthesized so that the core substance is in the outer shell and / or in the silica microcapsule.
Alternatively, there is provided a method for producing a composite silica microcapsule, wherein the composite silica microcapsule is included in a hollow portion at the center.

The second invention to be patented is that the stirring operation is carried out at the time of forming a water-in-oil emulsion and at the beginning of the reaction of hydrolysis and condensation polymerization of tetraalkoxysilane.
In the liquid state, high-speed stirring is performed, and in the particle formation stage in the middle stage of the reaction, the number of rotations of the stirring is gradually reduced, or
Pulse agitation in which agitation and agitation stop are repeated with the number of rotations of the agitation reduced, and further, in the solid-liquid state at the end of the reaction, agitation is stopped and aging is performed in combination to perform agitation. A method for producing a composite silica microcapsule according to the first invention, wherein a composite silica microcapsule having a size is prepared.

[0012] The third invention to be patented is that the core material is either an organic compound and / or an inorganic compound which is hardly soluble in an organic solvent in a continuous phase and easily soluble in water in a dispersed phase, or at least one of them. The method for producing a composite silica microcapsule according to the first aspect, wherein the method is a combination of two or more.

[0013] A fourth invention to be patented is a hydrochloric acid having an auxiliary agent soluble in a continuous phase and / or a dispersed phase and having a catalytic action to promote hydrolysis and polycondensation of tetraalkoxysilane. The method for producing a composite silica microcapsule according to the first invention, wherein any one of nitric acid, sulfuric acid, acetic acid, glacial acetic acid, formic acid, an acidic organic compound, and a surfactant is used alone or in combination of at least two or more. is there. The auxiliary agent is not limited to the above-mentioned catalyst, and may use, for example, a surfactant for dispersing oil droplets in the dispersed phase.

According to a fifth aspect of the present invention, a tetraalkoxysilane as a reactant is any one of tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, or a combination of at least two or more thereof. First
It is a manufacturing method of the composite silica microcapsule described in the invention.

According to a sixth aspect of the present invention, a surfactant is any of a carboxylate type, a sulfonate type, a sulfonate esterified salt type, a phosphate type anionic or amphoteric surfactant. Or a combination of at least two or more of them.

[0016] A seventh invention to be patented is a continuous invention comprising a low-polarity organic solvent which forms an interface with water, containing tetraalkoxysilane as a reactant and an auxiliary agent optionally added. Phase, a surfactant, and a dispersed phase consisting of a mixed solution containing a core substance and an auxiliary agent added as necessary to water in advance are mixed with each other so that the molar concentration ratio of water and the surfactant is increased. After the adjustment, a water-in-oil emulsion is formed while performing the stirring operation, and the hydrolysis and polycondensation reaction of the tetraalkoxysilane is caused by using the solubilized water of the water-in-oil emulsion as a reaction field while adjusting the stirring operation. The silica microcapsules prepared by the above method, wherein the silica microcapsules are configured such that a core substance is encapsulated in a shell at an outer peripheral portion and / or a hollow at a central portion of the silica microcapsules. In a black capsule, when the core substance contained therein is one containing a cationic organic compound or an amphoteric organic compound alone or in combination of at least two or more, the composite silica microcapsule is placed on the basic side from the isoelectric point of silica. In the external environment, the encapsulated core substance is not immobilized in the composite silica microcapsule, and conversely, by setting the external environment on the acidic side from the isoelectric point of silica, Immobilizing the core substance of the composite silica microcapsules, wherein all or a part of the single or a combination of at least two or more of the amphoteric organic compounds or amphoteric organic compounds is released from the composite silica microcapsules. This is a method for controlling the sustained release action.

The eighth invention to be patented is a continuous invention comprising a low-polarity organic solvent which forms an interface with water, containing tetraalkoxysilane as a reactant and an auxiliary agent added as required. Phase, a surfactant, and a dispersed phase consisting of a mixed solution containing a core substance and an auxiliary agent added as necessary to water in advance are mixed with each other so that the molar concentration ratio of water and the surfactant is increased. After the adjustment, a water-in-oil emulsion is formed while performing the stirring operation, and the hydrolysis and polycondensation reaction of the tetraalkoxysilane is caused by using the solubilized water of the water-in-oil emulsion as a reaction field while adjusting the stirring operation. The silica microcapsules prepared by the above method, wherein the silica microcapsules are configured such that a core substance is encapsulated in a shell at an outer peripheral portion and / or a hollow at a central portion of the silica microcapsules. In a black capsule, when the core substance contained therein contains an anionic organic compound alone or in combination of at least two or more, by passing water through the composite silica microcapsule, the core substance contained therein is Immobilization of the core substance of the composite silica microcapsule and sustained release action, wherein all or a part of the anionic organic compound alone or in combination of at least two or more kinds is released from the composite silica microcapsule. Control method

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. The hydrolysis and polycondensation reactions caused by the reaction substance tetraethoxysilane and water are represented by the following reaction formulas (1) and (2), respectively.

[0019]

[Formula 1]

The present invention provides a novel production method in which the above-mentioned hydrolysis and polycondensation reactions are carried out in a one-step reaction using a water-in-oil emulsion prepared so as to have a water content of between 20 and 300. It is intended to simply and efficiently prepare a composite silica microcapsule. The effectiveness of this new manufacturing method was confirmed by the following experiment.

<Example 1> The starting materials used in this example and the charged compositions thereof are shown. As the continuous phase, 200 ml of the reactant tetraethoxysilane and 100 ml of ethyl acetate,
A continuous phase is prepared by adding 200 ppm of acetic acid as a catalyst to this mixed solution. As a dispersed phase,
Three kinds of organic compounds were dissolved in ultrapure water (manufactured by Millipore) as a core substance so as to have a concentration of 1.0 × 10 ⁻² mol / l, and prepared as dispersed phases. Is 9.0 ml. One of the core substances is cationic rhodamine B (hereinafter abbreviated as RB),
Is a cationic methylene blue (hereinafter abbreviated as MB), and 3 is an anionic ethylenediaminetetraacetate (hereinafter abbreviated as EDTA-2Na).
Further, as a surfactant, 2.5 g of anionic sodium di-2-ethylhexyl sulfosuccinate (AOT) was used.
Prepare Here, the water content, which is the molar concentration ratio of water to the surfactant, is Wo = [H ₂ O] / [AOT] = 89, and the synthesis temperature is kept constant at 23 ° C.

The schematic diagram of the synthesizing apparatus used in Example 1 is shown in FIG.
As shown in FIG. In the figure, 1 is a stirring motor, 2 is a temperature controller, 3 is a constant temperature water tank, and 4 is a timer. A reaction tank is provided in the constant temperature water tank 3, and a stirring blade 5 is further provided in the reaction tank. The stirring blade 5 is a six-blade Rushton-type disk turbine blade.

The inventors carried out the operation of synthesizing the composite silica microcapsules as follows using the starting materials and the synthesis apparatus. FIG. 2 shows a flow of the synthesizing operation. First, as a continuous phase, tetraethoxysilane (TE
OS), a continuous phase in which ethyl acetate and acetic acid are mixed,
While AOT, which is a surfactant, is sufficiently dissolved in advance and continuously stirred, a dispersed phase in which RB is dissolved in ultrapure water, a dispersed phase in which cationic MB is dissolved in ultrapure water, or EDTA A water-in-oil emulsion is prepared by adding a dispersed phase obtained by dissolving -2Na in ultrapure water, and hydrolysis and condensation polymerization are initiated.

Further, in synthesizing the composite silica microcapsules in the present invention, the stirring operation plays an important role. Specifically, stirring was first performed at 170 rpm for 5 minutes, then the stirring speed was reduced to 90 rpm, stirring was performed at 90 rpm for 2 minutes, and a pulse stirring operation of stopping stirring for 2 minutes was performed for 16 hours, and finally stirring was performed. It was stopped and aging was performed for 24 hours. This is the point for producing micron-sized composite silica microcapsules.

After completion of the synthesis, the product was collected by suction filtration while washing with water using a membrane filter of 1 μm in pore size manufactured by Millipore. After collecting the particles,
Vacuum drying was performed for 4 hours to obtain a composite silica microcapsule product. Thereafter, the yield of the prepared composite silica microcapsules was confirmed based on the amount of water charged, and the observation and measurement of the particle shape and particle diameter were performed using a scanning electron microscope (SEM).

FIG. 3A shows an SEM photograph of a composite silica microcapsule containing MB, and FIG.
Fig. 2 shows an SEM photograph of the case where this was intentionally crushed.
This indicates that the particle shape of the composite silica microcapsules is spherical and clearly has a hollow structure.

With respect to the composite silica microcapsules containing RB and EDTA-2Na, it was confirmed by SEM that spherical silica microcapsules were respectively prepared.

The average particle size and the yield of the composite silica microcapsules are 32% at 2.3 μm for the composite silica microcapsules containing RB (RB-SiO ₂ ),
Composite silica microcapsules containing MB (MB-S
In the case of iO ₂ ), 52.7% at 4.0 μm,
Composite silica microcapsules containing 2Na (EDT
In the case of A-SiO ₂ ), it was 25% at 3.4 μm. The average particle diameter was obtained by directly using a caliper for 100 particle diameters from a scanning electron microscope (SEM) photograph.

The color of the composite silica microcapsules is RB
Composite silica microcapsules containing
B is a composite silica microcapsule containing blue, ED
The composite silica microcapsules containing TA-2Na were white.

Next, the R of the prepared cationic organic compound is
An experiment was performed on the immobilization ability of each of the composite silica microcapsules containing B and MB. FIG. 4 is a flowchart showing the analysis procedure. The procedure for analyzing the immobilizing ability of the composite silica microcapsules is as follows: the capsules are each filled with 0.3 g in a disposable type cartridge, conditioned by washing with water and drying through air,
Ultrapure water manufactured by Millipore or an aqueous solution of acetic acid having a pH of 2.0 was passed at 5 ml / min, and the eluate was placed in a volumetric flask every 10 ml, and the UV-visible spectrum of each eluate was measured.

The results of the UV-visible measurement are shown below. Figure
5 shows the UV-measurement results when water was passed, and FIG.
Is visible in the eluate when passing through an aqueous solution of acetic acid at pH 2.
It shows an absorption measurement result. RB-encapsulated composite silica
Microcapsule (RB-SiO _Two) And MB inclusion complex
Silica microcapsules (MB-SiO_Two) Of the eluate
The analysis was performed at measurement wavelengths of 566 nm and 668 n, respectively.
The absorption spectrum at m was measured. As a result,
MB-encapsulated composite silica microcapsules (MB-SiO
No elution occurs when the solution is passed through 2) (Fig.
5) When an aqueous solution of acetic acid at pH 2 is passed, the eluate contains M
Composite silica microcapsules with absorption based on B observed
Was confirmed to have eluted MB.

The reason for this is that when an aqueous solution more basic than the silica isoelectric point is passed through, the electrostatic interaction between negatively charged silica and positively charged MB causes
MB is strongly immobilized on the silica microcapsules and no elution occurs (FIG. 5). On the other hand, by passing an aqueous solution that is more acidic than the isoelectric point of silica, such as an aqueous acetic acid solution at pH 2, the silica becomes positive. It is considered that MB was eluted by being charged and the electrostatic interaction with the cationic organic compound being lost.

RB-encapsulated composite silica microcapsules (R
In the case of B-SiO ₂ ), the same tendency as in the case of the MB-encapsulated composite silica microcapsules was shown. However, when water was passed through, a small amount of RB based on RB was continuously observed. It was confirmed that water was continuously eluted from the RB-containing composite silica microcapsules (RB-SiO ₂ ) by water. Therefore, even though RB and MB are the same cationic organic compound, the elution behavior when water is passed through is different, indicating that MB is more strongly immobilized on silica microcapsules. This is because the atoms involved in the dissociation of organic compounds dissolved in water are nitrogen for RB and sulfur for MB, but the difference between the oxygen atom of silica and the electronegativity of sulfur is Is larger than the difference between the electronegativities of oxygen atoms and nitrogen, and MB is more strongly immobilized in silica microcapsules than RB because the electrostatic interaction between MB and silica works more strongly. Think of things.

On the other hand, when the absorption at 230 nm was measured using the immobilization ability of the composite silica microcapsules containing anionic EDTA-2Na as the measurement wavelength, water or p
No absorption was confirmed when each of the acetic acid aqueous solutions of H2 was passed. This is the separation of the preparation operation of FIG.
This is because EDTA-2Na was washed away from the EDTA-2Na composite silica microcapsules by washing with water in the recovery. To confirm this, instead of washing with water in the separation and recovery of the preparation operation, EDTA-2Na was used.
EDT prepared by washing with ethanol that is difficult to dissolve
A-2Na composite silica microcapsules (EDTA-
When water was passed through to analyze the immobilization ability of SiO ₂ ), absorption based on EDTA-2Na was confirmed at a wavelength of 230 nm.

It is considered that the reason for this is that water was easily eluted by water because there was no electrostatic interaction between negatively charged silica and negatively charged anionic EDTA-2Na. .

<Example 2> Starting materials used in this example
And its charge composition, as a continuous phase,
200 ml of toxic silane and 100 ml of ethyl acetate,
200 ppm of acetic acid was added as a catalyst to this mixture.
Prepare a continuous phase. As a dispersed phase,
Iron sulfate (FeS) as a core substance in ultrapure water (Millipore)
O₄・ 7H ₂O) heptahydrate 5.0 × 10^-2mol / l
Prepare a solution that has been dissolved to a concentration
Is 9.0 ml. In addition, as a surfactant
Di-2-ethylhexyl anionic sulfosuccinate
Prepare 2.5 g of sodium hydroxide. Where water and surface activity
The water content, which is the molar ratio of the agent, is Wo = [H_TwoO] / [AOT]
= 89, constant temperature of 23 ° C.
The same equipment used was used.

The inventors carried out the operation of synthesizing the composite silica microcapsules using the above-mentioned starting materials as follows. First, as a continuous phase, a mixed solution for a continuous phase formed by mixing tetraethoxysilane, ethyl acetate, and acetic acid,
While AOT was sufficiently dissolved in advance and continuous stirring was performed, a mixed solution for a disperse phase in which iron sulfate (FeSO ₄ .7H ₂ O) heptahydrate was dissolved in ultrapure water was added, and the mixture was added to oil. A water-based emulsion is prepared and hydrolysis and condensation reactions are started.

In this embodiment, the same method as the stirring operation in the first embodiment was employed. Specifically, after the disperse phase was charged, stirring was performed at 170 rpm for 5 minutes, and then the stirring speed was reduced to 90 rpm, stirring was performed at 90 rpm for 2 minutes, and a pulse stirring operation of stopping stirring for 2 minutes was performed for 16 hours. Finally, aging for stopping the stirring was performed for 24 hours.

After completion of the synthesis, the product was collected by suction filtration while washing with ethanol using a main membrane filter manufactured by Millipore with a pore size of 1 μm. After particle collection,
Vacuum drying was performed at 65 ° C. for 24 hours to obtain a composite silica microcapsule product. Thereafter, the yield of the prepared composite silica microcapsules was confirmed based on the amount of water charged, and the particle shape was observed and the particle size was measured by a scanning electron microscope (SEM).

[0040] Figure 7, iron sulfate _(FeSO 4 · _7H 2 O)
5 shows an SEM photograph of a composite silica microcapsule synthesized using an aqueous solution of heptahydrate as a dispersion phase. This indicates that the particle shape of the composite silica microcapsules is spherical. The average particle size and yield of the composite silica microcapsules were 4.1 μm and 60%, respectively.

FIG. 8 shows a photoelectron spectroscopic analysis (ESC) of silicon (Si), oxygen (O) and iron (Fe) of the silica microcapsule.
A: Results of depth analysis by Electron Spectroscopy for Chemical Analysis) and analysis conditions. Than this,
It is clear that iron is more present in the center of the composite silica microcapsule.

[0042]

[Effects] As described above, the present invention provides a simple pretreatment in which a core substance that is hardly soluble in an organic solvent in a continuous phase is dissolved in a dispersed phase, and the remaining water content is high. Micron-sized composite silica microcapsules containing a core substance by a one-step reaction in which solubilized water of a water-in-oil emulsion (W / O type) is used as a reaction site for hydrolysis and polycondensation of tetraalkoxysilane. Capsules can be easily prepared.

The composite silica microcapsules thus prepared are silica particles having a high sphericity of micron size, and the core substance is contained in the outer shell and / or in the outer shell.
Or it is included in the hollow.

According to the present invention, since an organic compound and / or an inorganic compound can be encapsulated in a silica microcapsule as a core substance, many types of composite silica microcapsules can be prepared.

The composite silica microcapsules prepared according to the present invention have the following characteristics. First, cationic organic compounds tend to be strongly immobilized within silica microcapsules by electrostatic interactions.

Second, among the cationic organic compounds,
The larger the difference in electronegativity between the atom involved in dissociation and the oxygen atom of silica is, the stronger the organic compound tends to be immobilized.

Third, the organic compound-composite silica microcapsules prepared according to the present invention can be controlled to be immobilized or released slowly by changing the external environment such as pH.

Fourthly, since anionic organic compounds have no electrostatic interaction with silica, they are easily eluted only by passing water through.

Fifth, among the inorganic compounds, an aqueous solution containing a metal cation, in particular, can be used as a reaction field in the present synthesis method, so that the silica microcapsules can be encapsulated.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a synthesizing apparatus used in the method for producing a composite silica microcapsule of the present invention.

FIG. 2 is a process flow of a method for producing a composite silica microcapsule according to the present invention.

FIG. 3A is a SEM photograph showing a composite silica microcapsule (MB-SiO ₂ ) containing MB.
(B) is a composite silica microcapsule containing MB (MB
-SiO ₂ ) is an SEM photograph obtained by intentionally crushing (SiO ₂ ).

FIG. 4 is a flowchart showing an analysis procedure of an experiment of an immobilization and sustained release action as a control method of the composite microcapsule.

FIG. 5 is an explanatory diagram showing the results of measuring a visible absorption spectrum when water is passed in an experiment on immobilization and sustained release as a control method of the composite microcapsule of the eighth invention.

FIG. 6 is an explanatory diagram showing visible absorption spectrum measurement results when an aqueous solution of acetic acid at pH 2 is passed in an experiment of immobilization and sustained release action, which is a method of controlling a composite microcapsule.

FIG. 7 is an SEM photograph of a composite silica microcapsule containing iron prepared by a method for producing a composite microcapsule.

FIG. 8 is a result of investigating abundance ratios of silicon (Si), oxygen (O), and iron (Fe) in a composite silica microcapsule containing iron by depth direction analysis using photoelectron spectroscopy.

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Claims (8)

[Claims] A surfactant is added to a continuous phase in which tetraalkoxysilane as a reactant and an auxiliary agent such as a catalyst optionally added are contained in an organic solvent having low polarity which forms an interface with water. And, a mixed solution containing a core substance and an auxiliary agent such as a catalyst or a surfactant previously added to water as needed was added as a disperse phase, and the molar concentration ratio of the water and the surfactant was adjusted to be higher. Further, a water-in-oil emulsion is formed while performing a stirring operation, and the hydrolysis and polycondensation reaction of tetraalkoxysilane are performed using the solubilized water of the water-in-oil emulsion as a reaction field while adjusting the stirring operation. Synthesizing a microcapsule so that the core substance is contained in the outer shell and / or the center hollow in the silica microcapsule. The method of producing a composite silica microcapsules with symptoms. 2. The stirring operation is carried out at a high rotation speed when a water-in-oil emulsion is formed and in a liquid-liquid state at the beginning of the hydrolysis and condensation polymerization of tetraalkoxysilane,
In the particle formation stage of the middle stage of the reaction, the number of revolutions of the stirring is gradually reduced, or pulse agitation in which the agitation and the stirring stop are repeated in a state where the number of revolutions of the agitation is reduced, and further, in the solid-liquid state at the end of the reaction, 2. The method for producing a composite silica microcapsule according to claim 1, wherein a combination of a stirring operation of aging with stopping stirring is performed to prepare a micron-sized composite silica microcapsule with high yield. . 3. The core material is one of an organic compound and / or an inorganic compound which is hardly soluble in an organic solvent in a continuous phase and easily soluble in water in a dispersed phase, or a combination of at least two or more thereof. Claim 1
3. The method for producing a composite silica microcapsule described in 1. above. 4. An auxiliary agent which is soluble in a continuous phase and / or a dispersed phase, and which has a catalytic action of promoting hydrolysis and condensation polymerization of tetraalkoxysilane, hydrochloric acid, nitric acid, sulfuric acid,
2. The method for producing composite silica microcapsules according to claim 1, wherein any one of acetic acid, glacial acetic acid, formic acid, an acidic organic compound, and a surfactant is used alone or in combination of at least two or more. 5. The method according to claim 1, wherein the tetraalkoxysilane as a reactant is any one of tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane and tetrabutoxysilane or a combination of at least two or more thereof. A method for producing the described composite silica microcapsules. 6. The surfactant may be any one of a carboxylate type, a sulfonate type, a sulfonic esterified salt type, a phosphate type anionic or amphoteric surfactant alone or in combination of at least two or more. The method for producing a composite silica microcapsule according to claim 1, wherein: 7. A continuous phase in which tetraalkoxysilane as a reactant and an auxiliary agent optionally added are contained in a low-polarity organic solvent which forms an interface with water, a surfactant, and water. A mixed phase containing a core material and a mixed solution containing an auxiliary agent added as needed is mixed with water, and the mixture is adjusted so that the molar concentration ratio of water and the surfactant is increased. There is a silica microcapsule formed by forming a water-in-oil emulsion and adjusting the stirring operation to cause hydrolysis and polycondensation reaction of tetraalkoxysilane using solubilized water of the water-in-oil emulsion as a reaction field. A composite silica microcapsule configured such that a core substance is encapsulated in a shell at an outer peripheral portion and / or a hollow at a central portion of the silica microcapsule. Core material there are, singly or at least two of the cationic organic compound or amphoteric organic compound
In the case of containing a combination of more than one kind, the core silica contained by making the composite silica microcapsules an external environment on the more basic side than the isoelectric point of silica, and without the state immobilized in the composite silica microcapsules Conversely, by setting the external environment on the acidic side from the isoelectric point of the silica, all or a part of the core organic substance or a combination of at least two or more of the cationic organic compound or the amphoteric organic compound is a composite silica. A method for immobilizing a core substance of a composite silica microcapsule and controlling a sustained release action, wherein the core substance is released from the microcapsule. 8. A continuous phase in which a tetraalkoxysilane as a reactant and an auxiliary agent optionally added are contained in a low-polarity organic solvent which forms an interface with water; a surfactant; To form a water-in-oil emulsion prepared by mixing a dispersion phase consisting of a core material and a mixed solution containing an auxiliary agent added as needed, so that the molar concentration ratio between water and the surfactant is increased. Then, while adjusting the stirring operation, there is a silica microcapsule prepared by causing hydrolysis and polycondensation reaction of tetraalkoxysilane using the solubilized water of the water-in-oil emulsion as a reaction field, and the outer periphery of the silica microcapsule. In a composite silica microcapsule constituted so that a core substance is encapsulated in a shell of a part and / or a hollow part in a central part, an aniline is contained in the encapsulated core substance. If it contains a single or at least two or more combinations of emission of organic compound, by passing water to the composite silica microcapsules,
Immobilizing a core material of a composite silica microcapsule, wherein all or a part of an anionic organic compound alone or a combination of at least two or more of the core materials contained therein is released from the composite silica microcapsule. And control method of controlled release action.