Production method of silica capsule particles containing oil solution

Abstract

To provide a production method of silica capsule particles containing an oil solution, where the rate of inclusion of the oil solution is high.SOLUTION: Provided is a production method of silica capsule particles containing an oil solution, the silica capsule comprising a core containing an oil solution and a shell containing silica as a constituent. The production method comprises Step 1: a step of emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor by an inline emulsifying disperser to obtain an emulsion and Step 2: a step of forming silica capsule particles containing the oil solution in a batch-type agitation tank using the emulsion obtained in Step 1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing oil-containing silica capsule particles. [Background technology]

[0002] Conventionally, attempts have been made to prolong the effects of products by incorporating silica capsule particles containing oils obtained by encapsulating oils such as perfumes and medicinal ingredients in silica capsule particles. In particular, for textile treatment products, cosmetics, detergents, etc., one of the important functions is to impart fragrance to clothing and the body, and products with long-lasting fragrances are in demand. In this situation, the synthesis of silica capsule particles containing oil by the sol-gel method has been investigated. For example, Patent Document 1 describes a method for producing microcapsules having a first shell and a second shell containing silica as a constituent component, and a core containing one or more organic compounds inside the first shell. Patent Document 2 describes a method for producing microcapsules having a shell containing silica as a constituent component and a core containing polymer particles and one or more oil-soluble liquids inside the shell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-128762 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-114802 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been found that when the manufacturing methods of Patent Documents 1 and 2 are used to produce a large amount of silica capsule particles containing an oil agent at once, the oil agent cannot be sufficiently encapsulated, and the encapsulation rate of the oil agent may decrease. An object of the present invention is to provide a method for producing oil-containing silica capsule particles that have a high encapsulation rate of oil. [Means for solving the problem]

[0005] The present inventors have discovered that the above-mentioned problems can be solved by emulsifying silica capsule particles containing an oil agent in an in-line emulsifying disperser and then using the emulsion to form silica capsule particles containing an oil agent in a batch-type stirring tank in the production of silica capsule particles containing an oil agent. That is, the present invention provides a method for producing oil-containing silica capsule particles having a core containing an oil and a shell containing silica as a constituent component, Step 1: Emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor in an in-line emulsifying disperser to obtain an emulsion; and Step 2: Using the emulsion obtained in Step 1, a method for producing oil-containing silica capsule particles is provided. [Effects of the Invention]

[0006] According to the present invention, a method for producing oil-containing silica capsule particles with a high encapsulation rate of oil can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Method of manufacturing oil-containing silica capsule particles] The production method of the present invention is a production method of oil-containing silica capsule particles (hereinafter simply referred to as "silica capsule particles") having a core containing an oil and a shell containing silica as a constituent component, Step 1: Emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor in an in-line emulsifying disperser to obtain an emulsion; and Step 2: Using the emulsion obtained in Step 1, oil-containing silica capsule particles are formed in a batch-type stirring tank.

[0008] In the present invention, the "reaction rate of the silica precursor" refers to the proportion of the silica precursor that has reacted, even if only partially, in the emulsion. For example, when tetraalkoxysilane is used as the silica precursor, the reaction rate is calculated assuming that the partially hydrolyzed product of the tetraalkoxysilane has reacted. The specific method for calculating the reaction rate of the silica precursor will be described in the Examples. In addition, in the present invention, the "encapsulation rate of oil agent" means the ratio of the amount of oil agent encapsulated in silica capsule particles to the blended amount of oil agent, and is specifically measured and calculated by the method described in the examples.

[0009] According to the present invention, it is possible to produce oil-containing silica capsule particles with a high encapsulation rate of oil. The reason for this is not entirely clear, but is thought to be as follows. In the present invention, in step 1, an oil agent mixed solution is emulsified in an in-line emulsifying disperser to obtain an emulsion, and then in step 2, the emulsion is subjected to a sol-gel reaction in a batch-type stirring tank to form oil agent-containing silica capsule particles. An example of an installation mode of the in-line emulsifying / dispersing machine used in step 1 is a mode in which the in-line emulsifying / dispersing machine is attached to the outside of a storage tank that stores the oil agent mixture. In this mode, the oil agent mixture is supplied from the storage tank to the in-line emulsifying / dispersing machine, and the oil agent mixture can be emulsified in an emulsifying / dispersing chamber within the emulsifying / dispersing machine. Alternatively, another installation mode of the in-line emulsifying / dispersing machine used in step 1 is a mode in which an in-line mixing section that mixes the surfactant, water, oil agent, and silica precursor in-line is provided, and the in-line emulsifying / dispersing machine is attached to a line from the mixing section. In this mode, the oil agent mixture is supplied from the in-line mixing section to the in-line emulsifying / dispersing machine, and the oil agent mixture is emulsified in the emulsifying / dispersing chamber within the emulsifying / dispersing machine, and the emulsion can then be supplied to the storage tank. In either mode, the volume of the emulsifying / dispersing chamber within the emulsifying / dispersing machine is smaller than the storage tank, allowing shear force to be efficiently applied to the oil agent mixture. By including Step 1, even when a large amount of oil solution mixture is used, it is thought that the emulsification of the oil solution mixture can be promoted rather than the sol-gel reaction of the silica precursor (reaction of the silica precursor), and an emulsion can be obtained quickly, the formation of a shell during emulsification can be suppressed, and the destruction of the shell due to the application of shear force can be suppressed. In step 2, the emulsion obtained in step 1 is subjected to a sol-gel reaction in a batch-type stirring tank, which is thought to suppress partial or total destruction of the emulsion droplets, form silica capsule particles with dense and strong shells, and increase the encapsulation rate of the oil agent. Here, the term "sol-gel reaction" refers to a reaction in which a silica precursor undergoes hydrolysis and polycondensation reactions to go through a sol and gel state to form silica, which is a component of the shell of an oil-containing silica capsule particle. Examples of the sol-gel reaction include a reaction in which a tetraalkoxysilane as a silica precursor is hydrolyzed, a silanol compound undergoes a dealcoholization condensation reaction and a dehydration condensation reaction to produce a siloxane oligomer, and the dehydration condensation reaction further progresses to form silica.

[0010] <Process 1> Step 1 is a step of emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor in an in-line emulsifying disperser to obtain an emulsion. The oil agent mixture used in step 1 comprises an aqueous phase component containing a surfactant and water, and an oil phase component containing an oil agent and a silica precursor.

[0011] (Oil mixture) [Surfactant] The surfactant used in step 1 is preferably a cationic surfactant, from the viewpoint of increasing the encapsulation rate of the oil agent. Examples of cationic surfactants include alkylamine salts, alkyl quaternary ammonium salts, etc. The number of carbon atoms in the alkyl group of the alkylamine salts and alkyl quaternary ammonium salts is preferably 10 or more, more preferably 12 or more, and even more preferably 14 or more, and is preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less. Examples of alkylamine salts include alkylamine acetates such as laurylamine acetate and stearylamine acetate. Examples of alkyl quaternary ammonium salts include alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, and alkyl benzyl dimethyl ammonium salts.

[0012] Examples of alkyltrimethylammonium salts include alkyltrimethylammonium chlorides such as lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, and stearyltrimethylammonium chloride; and alkyltrimethylammonium bromides such as lauryltrimethylammonium bromide, cetyltrimethylammonium bromide, and stearyltrimethylammonium bromide. Examples of dialkyldimethylammonium salts include dialkyldimethylammonium chlorides such as distearyldimethylammonium chloride; and dialkyldimethylammonium bromides such as distearyldimethylammonium bromide. Examples of alkylbenzyldimethylammonium salts include alkylbenzyldimethylammonium chloride and alkylbenzyldimethylammonium bromide. The cationic surfactants can be used alone or in combination of two or more.

[0013] Among these, the cationic surfactant is preferably a quaternary ammonium salt, more preferably an alkyltrimethylammonium salt having an alkyl group having from 10 to 22 carbon atoms, even more preferably one or more selected from lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, and cetyltrimethylammonium chloride, and even more preferably cetyltrimethylammonium chloride.

[0014] From the viewpoint of obtaining a stable emulsion, the amount of surfactant used in step 1 is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the oil used in step 1, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 1 part by mass or less, and even more preferably 0.7 parts by mass or less.

[0015] 〔water〕 The water used in step 1 is preferably one or more selected from ion-exchanged water and distilled water.

[0016] From the viewpoint of obtaining a stable emulsion, the amount of water used in step 1 is preferably 100 parts by mass or more, more preferably 130 parts by mass or more, even more preferably 150 parts by mass or more, relative to 100 parts by mass of the oil used in step 1, and is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less.

[0017] [Oil] The oil used in step 1 becomes the encapsulated component of the resulting silica capsule particles. The oil is preferably one or more selected from fragrances, fragrance precursors, moisturizers, antioxidants, antibacterial agents, fertilizers, surface modifiers for fibers, skin, hair, etc., cooling agents, dyes, pigments, silicones, and oil-soluble polymers, more preferably one or more selected from fragrances, fragrance precursors, moisturizers, antioxidants, antibacterial agents, fertilizers, and surface modifiers, even more preferably one or more selected from fragrances, fragrance precursors, moisturizers, and antioxidants, still more preferably one or more selected from fragrances, fragrance precursors, and moisturizers, and even more preferably one or more selected from fragrances and fragrance precursors. The oil agents can be used alone or in combination of two or more.

[0018] Examples of the fragrance precursor include a compound that releases a fragrance component in response to water, a compound that releases a fragrance component in response to light, and the like. Examples of compounds that release fragrance components in reaction with water include silicate ester compounds having an alkoxy component derived from a fragrance alcohol, fatty acid ester compounds having an alkoxy component derived from a fragrance alcohol, acetal compounds or hemiacetal compounds obtained by reacting a carbonyl component derived from a fragrance aldehyde or fragrance ketone with an alcohol compound, Schiff base compounds obtained by reacting a carbonyl component derived from a fragrance aldehyde or fragrance ketone with a primary amine compound, and hemiaminal compounds or hydrazone compounds obtained by reacting a carbonyl component derived from a fragrance aldehyde or fragrance ketone with a hydrazine compound. Examples of compounds that release fragrance components in response to light include 2-nitrobenzyl ether compounds having an alkoxy component derived from a fragrance alcohol, α-ketoester compounds having a carbonyl component derived from a fragrance aldehyde or fragrance ketone, and coumaric acid ester compounds having an alkoxy component derived from a fragrance alcohol. These fragrance precursors may be used as polymers, such as the reaction product of a portion of the carboxyl groups of polyacrylic acid with a fragrance alcohol.

[0019] The calculated value of the common logarithm "LogP" of the partition coefficient P (n-octanol / water) of the oil agent between n-octanol and water (hereinafter also referred to as "cLogP value") is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, from the viewpoint of obtaining a stable emulsion, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less. When the oil is composed of a plurality of components, the cLogP value of the oil can be determined by multiplying the cLogP value of each component by the volume ratio of each component and calculating the sum of the results. When the cLogP value of the oil agent is 1 or more, the encapsulation rate of the oil agent in the resulting silica capsule particles can be increased in the sol-gel reaction of the silica precursor. Similarly, even when the oil agent is a fragrance composition composed of multiple fragrance components, when the cLogP value of the fragrance composition is 1 or more, the encapsulation rate of the fragrance composition in the resulting silica capsule particles can be increased. Here, the cLogP value is "LogP (cLogP)" calculated by the method described in A. Leo Comprehensive Medicinal Chemistry, Vol. 4, C. Hansch, P.G. Sammens, J.B. Taylor and C.A. Ramsden, Eds., p. 295, Pergamon Press, 1990, and the cLogP value calculated using the program CLOGP v4.01 can be used.

[0020] [Silica precursor] From the viewpoints of suppressing the reaction of the silica precursor in step 1, swiftly progressing emulsification, and increasing the encapsulation rate of the oil agent, the silica precursor used in step 1 preferably contains a tetraalkoxysilane, more preferably a tetraalkoxysilane having an alkoxy group having from 1 to 4 carbon atoms, even more preferably one or more selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane, even more preferably one or more selected from tetramethoxysilane and tetraethoxysilane, and even more preferably tetraethoxysilane. When the silica precursor contains a tetraalkoxysilane, it may also contain a trialkoxysilane such as triethoxysilane or trimethoxysilane, but the content of the tetraalkoxysilane in the silica precursor is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less.

[0021] The amount of silica precursor used in step 1 is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the oil used in step 1, from the viewpoint of forming a shell that can surround the emulsion droplets containing the oil; and from the viewpoint of suppressing the silica precursor from remaining inside the emulsion droplets in the sol-gel reaction and efficiently progressing the conversion to a shell, the amount is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0022] The oil agent mixture used in step 1 may contain an emulsifying aid, a particle size stabilizer, and the like as oil phase components other than the oil agent and the silica precursor.

[0023] [Emulsifying aid] The emulsification aid is preferably one or more selected from higher aliphatic alcohols having 6 or more carbon atoms, higher fatty acids having 6 or more carbon atoms, monoalkyl glyceryl ethers having an alkyl group having 6 or more carbon atoms, and amide compounds having an alkyl group having 8 or more carbon atoms. These emulsifying aids contain long-chain aliphatic hydrocarbon groups and polar groups, and are therefore thought to be able to suppress the reaction of the silica precursor during the emulsification of the oil solution mixture in step 1, while facilitating rapid emulsification and increasing the encapsulation rate of the oil solution. The emulsification aids can be used alone or in combination of two or more. The molecular weight of the emulsification aid is preferably 500 or less, more preferably 450 or less, even more preferably 400 or less, still more preferably 350 or less, and preferably 150 or more, from the viewpoint of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent.

[0024] The number of carbon atoms in the higher aliphatic alcohol is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, and still more preferably 14 or more, from the viewpoints of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent, and is preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less. From the same viewpoint as above, the higher aliphatic alcohol is preferably a linear or branched higher aliphatic alcohol, and more preferably a linear higher aliphatic primary alcohol. From the viewpoint of ease of handling, the higher aliphatic alcohol is preferably solid (for example, has a melting point of 30°C or higher) at room temperature and normal pressure. The melting point of the higher aliphatic alcohol is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and still more preferably 45°C or higher. Examples of the higher aliphatic primary alcohols include 2-ethylhexyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, oleyl alcohol, etc. Among these, preferred is one or more selected from 2-ethylhexyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol, more preferred is one or more selected from cetyl alcohol and stearyl alcohol, and even more preferred is cetyl alcohol.

[0025] The carbon number of the higher fatty acid is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, still more preferably 14 or more, still more preferably 16 or more, from the viewpoint of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent, and is preferably 26 or less, more preferably 22 or less, and even more preferably 20 or less. Examples of the higher fatty acids include 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, lanolic acid, isostearic acid, etc. Among these, branched-chain saturated fatty acids are preferred, and isostearic acid is more preferred.

[0026] The number of carbon atoms in the alkyl group of the monoalkyl glyceryl ether is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and still more preferably 16 or more, from the viewpoints of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent, and is preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Examples of the monoalkyl glyceryl ether include mono-2-ethylhexyl glyceryl ether, monodecyl glyceryl ether, monolauryl glyceryl ether, monomyristyl glyceryl ether, monocetyl glyceryl ether, monostearyl glyceryl ether, and monobehenyl glyceryl ether. Among these, one or more selected from monocetyl glyceryl ether, monostearyl glyceryl ether, and monobehenyl glyceryl ether are preferred, and monostearyl glyceryl ether is more preferred. The monoalkyl glyceryl ether is usually in the α-form.

[0027] The number of carbon atoms in the alkyl group of the amide compound is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, from the viewpoints of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent, and is preferably 22 or less, more preferably 20 or less, even more preferably 18 or less. The amide compound is preferably an amide compound having an alkyl group derived from a saturated or unsaturated fatty acid, such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, or oleic acid amide.

[0028] The cLogP value of the emulsification aid is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, from the viewpoint of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent, and is preferably 10 or less, more preferably 9 or less.

[0029] Furthermore, the higher fatty acid and the higher aliphatic alcohol are considered to function as particle size stabilizers that stabilize the particle size of emulsified droplets, in addition to their function as emulsifying aids. From this perspective, the oil agent mixture used in step 1 preferably contains, as an oil phase component other than the oil agent and the silica precursor, one or more selected from higher fatty acids having 6 or more carbon atoms and higher aliphatic alcohols having 6 or more carbon atoms, and more preferably contains a higher fatty acid having 6 or more carbon atoms.

[0030] When the oil agent mixture used in step 1 further contains the emulsification aid as an oil phase component, the amount of the emulsification aid is, from the viewpoints of suppressing the reaction of the silica precursor while swiftly progressing emulsification and increasing the encapsulation rate of the oil agent, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, relative to 100 parts by mass of the oil agent used in step 1.

[0031] [Particle size stabilizer] Examples of particle size stabilizers include fatty acid esters having a total carbon number of 6 or more. The particle size stabilizer is thought to contribute to suppressing destabilization of emulsion droplets due to Ostwald ripening, in which relatively hydrophilic components in the oil phase of emulsion droplets diffuse molecularly into the aqueous phase (continuous phase), thereby suppressing coarsening of emulsion droplets over time and stabilizing the particle size of emulsion droplets. Therefore, by using the particle size stabilizer in combination with the emulsification aid, it is thought that it is possible to suppress the reaction of the silica precursor, rapidly progress emulsification, provide a suitable shell formation site as a template for silica capsule particles, and increase the encapsulation rate of the oil agent. From this perspective, the clogP value of the particle size stabilizer is preferably 4 or more, more preferably 5 or more, even more preferably 6 or more, and even more preferably 7 or more, and preferably 10 or less, more preferably 9 or less.

[0032] The total number of carbon atoms in the fatty acid ester is preferably 10 or more, more preferably 14 or more, even more preferably 18 or more, and preferably 50 or less, from the viewpoints of suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent. Examples of the fatty acid ester include fatty acid monoesters of fatty acids and monohydric alcohols, fatty acid diesters of fatty acids and dihydric alcohols, dicarboxylic acid diesters of dicarboxylic acids and monohydric alcohols, tricarboxylic acid triesters of tricarboxylic acids and monohydric alcohols, glycerin fatty acid triesters, etc. Among these, fatty acid monoesters are preferred from the viewpoints of suppressing the reaction of the silica precursor, rapidly promoting emulsification, and increasing the encapsulation rate of the oil agent. The fatty acid monoester preferably comprises a fatty acid having 8 to 22 carbon atoms and a monohydric alcohol having 1 to 24 carbon atoms. Examples of fatty acids constituting the fatty acid monoester include saturated or unsaturated fatty acids having 8 to 22 carbon atoms, such as 2-ethylhexanoic acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, margadelic acid, stearic acid, oleic acid, linoleic acid, erucic acid, arachidic acid, and behenic acid. Examples of the monohydric alcohol constituting the fatty acid monoester include aliphatic monohydric alcohols having 1 to 24 carbon atoms, such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, n-pentyl alcohol, isopentyl alcohol, neopentyl alcohol, hexanol, heptanol, octanol, 2-ethylhexyl alcohol, nonanol, isononyl alcohol, decanol, isodecyl alcohol, dodecanol, lauryl alcohol, tridecanol, myristyl alcohol, pentadecanol, cetyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, behenyl alcohol, and 2-octyldodecanol. Examples of the fatty acid monoester include cetyl 2-ethylhexanoate, butyl stearate, isopropyl myristate, hexadecyl myristate, 2-octyldodecyl myristate, isopropyl palmitate, hexadecyl palmitate, 2-ethylhexyl stearate, etc. Among these, isopropyl palmitate is preferred.

[0033] When the oil agent mixture used in step 1 further contains the particle size stabilizer as an oil phase component, the amount of the particle size stabilizer is, from the viewpoint of suppressing the reaction of the silica precursor, swiftly progressing emulsification, and increasing the encapsulation rate of the oil agent, preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, relative to 100 parts by mass of the oil agent used in step 1.

[0034] The mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing a surfactant and water to the oil phase component containing an oil and a silica precursor in the oil agent mixture used in step 1 is preferably 50 / 50 or more, more preferably 53 / 47 or more, and even more preferably 57 / 43 or more, from the viewpoint of obtaining a stable emulsion, and is preferably 99 / 1 or less, more preferably 95 / 5 or less, even more preferably 90 / 10 or less, still more preferably 80 / 20 or less, and still more preferably 70 / 30 or less, from the viewpoint of production efficiency.

[0035] (Emulsification of oil mixture) A preferred emulsification method in step 1 is a method in which an aqueous phase component and an oil phase component prepared in advance are mixed in a storage tank to prepare an oil agent mixture, and then the oil agent mixture is supplied to an in-line emulsifying disperser provided outside the storage tank to carry out emulsification. In preparing the oil agent mixture in this method, the order in which the aqueous phase component and the oil phase component are charged into the storage tank is not particularly limited, but from the viewpoint of ease of production, it is preferable to prepare the aqueous phase component in the storage tank and then add a separately prepared oil phase component. The storage tank is preferably equipped with a stirring device having a stirring blade. Examples of the stirring blade include a paddle blade, a turbine blade, an anchor blade, a ribbon blade, a propeller, etc. In this case, from the viewpoint of production efficiency, it is preferable to use the batch-type stirring tank used in step 2 as the storage tank. Alternatively, as another preferred emulsification method in step 1, a method in which a surfactant, water, an oil agent, and a silica precursor are mixed in-line to prepare an oil agent mixture, and then the oil agent mixture is supplied to an in-line emulsifying disperser to carry out emulsification is also mentioned. When the oil agent mixture is prepared by in-line mixing, it is preferable to obtain the oil agent mixture by mixing an aqueous phase component containing a surfactant and water and an oil phase component containing an oil agent and a silica precursor in a single line (in a pipe). The aqueous phase component to be mixed in-line is preferably prepared using a stirring device with stirring blades. Examples of the stirring blades include the same stirring blades as those used in the storage tank. The oil phase component to be mixed in-line may be prepared using a stirring device with stirring blades, or may be prepared by mixing the oil agent and the silica precursor in-line. For the in-line mixing, it is preferable to use an in-line mixer such as a static mixer.

[0036] When the aqueous phase component is prepared using the stirring device, the stirring rotation speed in preparing the aqueous phase component is preferably 20 r / min or more, more preferably 30 r / min or more, and even more preferably 50 r / min or more, taking into consideration the tip peripheral speed, and is preferably 120 r / min or less, more preferably 100 r / min or less, and even more preferably 90 r / min or less, from the viewpoint of suppressing temperature rise due to stirring. In the present invention, the "tip peripheral speed" means the peripheral speed of the outer periphery of the largest stirring blade (main stirring blade) in the stirring device when a stirring blade is used. The liquid temperature during stirring in the preparation of the aqueous phase component using the stirring device is preferably 0°C or higher, and preferably 40°C or lower, more preferably 35°C or lower. The stirring time in preparing the aqueous phase component using the stirring device varies depending on the production scale, stirring speed, temperature conditions, etc., but is preferably 3 minutes or more, more preferably 5 minutes or more, even more preferably 10 minutes or more, and is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 20 minutes or less.

[0037] The amount of the oil mixture used in step 1 is preferably 10 kg or more, more preferably 100 kg or more, even more preferably 300 kg or more, still more preferably 500 kg or more, and still more preferably 1,000 kg or more from the viewpoint of productivity, and is preferably 100,000 kg or less, more preferably 10,000 kg or less from the viewpoint of equipment. In the present invention, a large amount of the oil solution mixture means that the amount of the oil solution mixture used in step 1 is 100 kg or more.

[0038] When the oil agent mixture is prepared in a storage tank, the oil agent mixture in the storage tank is preferably supplied to the in-line emulsifying disperser while being circulated and mixed by the above-mentioned stirring blade in step 1. The stirring rotation speed at this time is, taking into consideration the tip peripheral speed, preferably 20 r / min or more, more preferably 30 r / min or more, and even more preferably 50 r / min or more, and from the viewpoint of suppressing a temperature rise due to stirring, preferably 120 r / min or less, more preferably 100 r / min or less, and even more preferably 90 r / min or less.

[0039] Furthermore, when the oil agent mixture is prepared in a storage tank, the oil agent mixture used in step 1 may be pre-emulsified with the above-mentioned stirring blade before being supplied to the in-line emulsifying disperser. The preferred range of the stirring rotation speed in this case is the same as the preferred range of the stirring rotation speed during the above-mentioned circulation mixing. The temperature of the oil mixture to be subjected to preliminary emulsification is preferably 0°C or higher, and preferably 40°C or lower, more preferably 35°C or lower. The stirring time in preliminary emulsification varies depending on the production scale, stirring speed, temperature conditions, etc., but is preferably 3 minutes or more, more preferably 5 minutes or more, even more preferably 10 minutes or more, and is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 20 minutes or less.

[0040] The emulsification in step 1 is carried out using an in-line emulsifying disperser from the viewpoint of suppressing the reaction of the silica precursor, allowing the emulsification to proceed quickly, and increasing the encapsulation rate of the oil agent. The emulsification in step 1 may be a "one-pass method" in which the oil agent mixture is passed through an in-line emulsifying disperser only once, or a "multi-pass method" in which the emulsion obtained by passing the oil agent mixture through an in-line emulsifying disperser is passed through the in-line emulsifying disperser again at least partially or entirely multiple times. An example of a one-pass method is the in-line method. Examples of the multi-pass method include an "external circulation method," a "catch ball method," a "liquid return method," and an "in-line method."

[0041] The external circulation system is a system in which the oil mixture is discharged from a storage tank equipped with an external circulation line through which an in-line emulsifying disperser is installed, and after emulsification using the in-line emulsifying disperser, the emulsion is returned to the storage tank via the external circulation line, and the emulsion is circulated between the in-line emulsifying disperser and the storage tank. The catch-ball method is a method in which a line with an in-line emulsifier / disperser is set up between two storage tanks, and the emulsion is sent back and forth between the storage tanks through this line. The liquid return method is a method in which a line connects two storage tanks and an in-line emulsifying disperser so that the liquid circulates between them, and after the entire amount of liquid has passed through the in-line emulsifying disperser, the liquid is returned to the original storage tank, and the process is repeated. A preferred in-line method is a method in which a surfactant, water, an oil agent, and a silica precursor are mixed in-line to prepare an oil agent mixture, and then the oil agent mixture is supplied to an in-line emulsifying disperser and emulsified by the in-line emulsifying disperser.

[0042] Among these methods, from the viewpoint of suppressing the reaction of the silica precursor, rapidly progressing the emulsification, increasing the encapsulation rate of the oil agent, and facilitating the design of the equipment, it is preferable to carry out the emulsification in step 1 by an external circulation method or an inline method using an inline emulsifying disperser. In the case of the external circulation type, it is preferable to circulate the emulsion between the in-line emulsifying disperser and one storage tank via an external circulation line, from the viewpoint of suppressing the reaction of the silica precursor, rapidly progressing the emulsification, increasing the encapsulation rate of the oil agent, and facilitating facility design. Even in the case of the external circulation type, the oil agent mixture may be discharged from the storage tank through an external circulation line, emulsified by an in-line emulsifying disperser, and then returned to the same storage tank as the original storage tank through the external circulation line, or may be transferred to a storage tank different from the original storage tank through a line. In the case of the in-line type, it is preferable that an in-line emulsifying / dispersing machine is attached to a line extending from an in-line mixing section that mixes the surfactant, water, oil, and silica precursor in-line, and that the mixture is emulsified by the in-line emulsifying / dispersing machine. In the case of the in-line type, the oil solution mixture mixed in-line may be passed through the in-line emulsifying disperser one or more times. That is, in the case of the in-line type, the number of passes may be one (one-pass type) or multiple (multi-pass type). In the in-line type, when the oil agent mixture is passed through the in-line emulsifying disperser multiple times, it is preferable to store the emulsion obtained by passing the oil agent mixture discharged from the in-line mixing section through the in-line emulsifying disperser in a storage tank, connect the storage tank and the in-line emulsifying disperser with a line so that the liquid circulates, and further pass at least a part or all of the emulsion through the in-line emulsifying disperser. In any of the above methods, two or more in-line emulsifying and dispersing machines may be connected together.

[0043] The in-line emulsifying disperser preferably has a rotor and a stator from the viewpoints of efficiently applying shear force to the oil agent mixture, suppressing the reaction of the silica precursor, rapidly progressing emulsification, and increasing the encapsulation rate of the oil agent. An emulsifying / dispersing machine having a rotor and a stator is any dispersing machine that utilizes the shear field generated between the rotor (rotating part) and the stator (non-rotating part) in the emulsifying / dispersing chamber. That is, the shear rate can be adjusted by varying the clearance between the rotor and the stator and the rotation speed of the rotor, and the oil agent mixture passes between the rotor and the stator rotating in the emulsifying / dispersing chamber, thereby applying a shear force to the oil agent mixture and emulsifying it. Examples of in-line emulsifying dispersers include Cavitron (manufactured by Eurotech Co., Ltd.) and Milder (manufactured by Pacific Machinery Works, Ltd.). Among these, Cavitron (manufactured by Eurotech Co., Ltd.) or Milder (manufactured by Pacific Machinery Works, Ltd.) are preferred from the viewpoint of being able to impart a desired shear force to the oil agent mixture, and Cavitron (manufactured by Eurotech Co., Ltd.) is a particularly preferred example.

[0044] The shear force applied to the oil agent mixture in the emulsification in step 1 is preferably adjusted using the rotational energy Q of the rotor per volume of the emulsification / dispersion chamber of the in-line emulsification / dispersion machine as an index. The rotational energy Q of the rotor per volume of the emulsifying / dispersing chamber of an in-line emulsifying / dispersing machine can be calculated based on the following formula (I). Rotational energy Q (W / m 3 ) = [rotor rotation power required P (W)] / [in-line emulsifying and dispersing machine emulsifying and dispersing chamber volume (m 3 ) (I) In formula (I), the rotational power required for the rotor, P (W), is calculated using the following (empirical formula 1). Rotor rotation power required P(W)=n 3 ×d 5 ×ρ (Empirical formula 1) n: Rotor rotation speed (s -1 ) d: outer diameter of rotor (m) ρ: Density of oil mixture (kg / m 3 ) Here, ρ is 1000 (kg / m 3 ) is used as an approximation. The rotational energy Q is preferably 1×10 from the viewpoint of increasing the shearing effect on the oil solution mixture and suppressing the reaction rate of the silica precursor while rapidly producing a fine emulsion having an average particle size of 10 μm or less. 7 W / m 3 or more, more preferably 1×10 8 W / m 3 More preferably, 1×10 9 W / m 3 From the viewpoint of production efficiency, the rotational energy Q is preferably 1×10 12 W / m 3 It may be the following:

[0045] In addition, the shear force applied to the oil agent mixture in the emulsification in step 1 may be adjusted using as an index the rotational energy Q' obtained by taking into account the emulsification time and the rotational energy Q of the rotor per volume of the emulsification dispersion chamber of the in-line emulsification dispersion machine. The rotational energy Q' is calculated based on the following formula (II). Rotational energy Q'(W·h / m 3 ) = [[Required rotor rotation power P (W)] × [Emulsification time (h)]] / [Volume of the emulsification dispersion chamber of the in-line emulsification dispersion machine (m 3 ) (II) In formula (II), the rotational power required for the rotor P(W), n, d, and ρ are the same as those in formula (I). Here, ρ is 1000 (kg / m 3 ) is used as an approximation. The rotational energy Q' is preferably 1×10 from the viewpoint of increasing the shearing effect on the oil solution mixture and suppressing the reaction rate of the silica precursor while rapidly producing a fine emulsion having an average particle size of 10 μm or less. 6 W·h / m 3 or more, more preferably 1×10 7 W·h / m 3 More preferably, 1×10 8 W·h / m 3 From the viewpoint of production efficiency, the rotational energy Q' is preferably 1×10 12 W·h / m 3 It may be the following:

[0046] In addition, when multiple in-line emulsifying / dispersing machines are used in series, or when an in-line emulsifying / dispersing machine having rotors and stators in multiple stages within an emulsifying / dispersing chamber, such as Milder (manufactured by Pacific Machinery Works, Ltd.), is used, the rotational power requirement P(W) of the rotor means the total of the rotational power requirements P(W) calculated for each in-line emulsifying / dispersing machine or the total of the rotational power requirements P(W) calculated for each stage. In addition, if the conditions such as the rotor rotation speed are changed during the emulsification in step 1, the rotational energy Q' (W h / m 3 ) is the rotational energy Q' (W h / m ) calculated from each condition and the emulsification time under that condition. 3 ) is calculated as the sum of

[0047] Furthermore, the rotational energy Q'(W h / m 3 ) divided by the amount (kg) of the oil mixture used in step 1, to obtain the rotational energy Q' (W h / m 3 ) (i.e., the rotor rotational energy Q'' (W·h / (m 3 kg))) is preferably 1×10 from the viewpoint of increasing the shear effect on the oil solution mixture, suppressing the reaction rate of the silica precursor, and rapidly producing a fine emulsion having an average particle size of 10 μm or less. 4 W·h / (m 3 kg) or more, more preferably 1×10 5 W·h / (m 3 kg) or more, more preferably 0.5 × 10 6 W·h / (m 3 From the viewpoint of production efficiency, the rotational energy Q'' is preferably 1×10 12 W·h / (m 3 · kg) or less.

[0048] The processing flow rate of the in-line emulsifying disperser is preferably 0.1 L / min or more, more preferably 0.5 L / min or more, even more preferably 1 L / min or more, and even more preferably 3 L / min or more, from the viewpoint of quickly producing a fine emulsion having an average particle size of 10 μm or less before the reaction of the silica precursor proceeds. Furthermore, from the viewpoint of ease of production, the processing flow rate may be preferably 1000 L / min or less.

[0049] The outermost peripheral speed of the rotor of the in-line emulsifying / dispersing machine is preferably 3 m / s or more, more preferably 5 m / s or more, even more preferably 10 m / s or more, still more preferably 15 m / s or more, and even more preferably 20 m / s or more, from the viewpoint of imparting the desired rotational energy, and is preferably 50 m / s or less, more preferably 45 m / s or less, from the viewpoint of suppressing an increase in liquid temperature in the emulsifying / dispersing chamber.

[0050] When the emulsification in step 1 is carried out using an in-line emulsifying disperser, the number of passes through the in-line emulsifying disperser in step 1 is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no particular upper limit, but from the perspective of production efficiency, the number is preferably 100,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, still more preferably 3,000 or less, still more preferably 2,000 or less, still more preferably 1,500 or less, and even more preferably 1,300 or less. The number of passes indicates the number of times the oil mixture is subjected to shear by the rotor, and is calculated based on the following calculation formula (III). Number of passes = [[Emulsification time (h) × 60] × [Circulation flow rate (kg / min)]] / [Amount of oil mixture used in step 1 (kg)] (III)

[0051] From the viewpoint of suppressing the reaction of the silica precursor, the liquid temperature of the oil agent mixture used for emulsification in step 1 is preferably 50° C. or lower, more preferably 40° C. or lower, even more preferably 35° C. or lower, and still more preferably 30° C. or lower. From the viewpoint of production efficiency, the liquid temperature of the oil agent mixture used for emulsification in step 1 may preferably be 0° C. or higher. The emulsification time in step 1 can be adjusted appropriately depending on the production scale, etc., but is preferably 12 hours or less, more preferably 10 hours or less, even more preferably 8 hours or less, still more preferably 6.5 hours or less, even more preferably 6 hours or less, still more preferably 5 hours or less, and even more preferably 4 hours or less, and from the viewpoint of ease of production, is preferably 0.003 hours or more, more preferably 0.01 hours or more, and even more preferably 0.1 hours or more. By shortening the emulsification time in step 1, the oil-water contact time can be shortened, and the reaction of the silica precursor can be suppressed. For example, when the amount of oil mixture used in step 1 is 100 kg or more, the emulsification time in step 1 is, from the viewpoint of suppressing the reaction of the silica precursor, preferably 12 hours or less, more preferably 10 hours or less, even more preferably 8 hours or less, still more preferably 6.5 hours or less, still more preferably 6 hours or less, still more preferably 5 hours or less, still more preferably 4 hours or less, and still more preferably 3 hours or less, and from the viewpoint of ease of production, is preferably 0.1 hour or more.

[0052] The median diameter D of the emulsion droplets obtained in step 1 50 is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, and even more preferably 0.7 μm or more, from the viewpoint of reducing the specific surface area of ​​the resulting silica capsule particles relative to the external environment and improving the retention of the oil agent, and is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, even more preferably 3 μm or less, even more preferably 2 μm or less, and even more preferably 1.5 μm or less, from the viewpoint of the dispersion stability of the resulting silica capsule particles. The median diameter D of the emulsified droplets 50 can be measured by the method described in the Examples. The reactivity of the silica precursor in the emulsion obtained in step 1 is preferably 80% or less, more preferably 70% or less, even more preferably 60% or less, still more preferably 55% or less, still more preferably 50% or less, still more preferably 40% or less, still more preferably 35% or less, and still more preferably 30% or less, from the viewpoint of increasing the encapsulation rate of the oil agent, and is 0% or more, and from the viewpoint of ease of production, is preferably 1% or more. The reaction rate of the silica precursor can be measured by the method described in the Examples.

[0053] <Process 2> (Formation of silica capsule particles) Step 2 is a step of forming oil-containing silica capsule particles in a batch-type stirring tank using the emulsion obtained in step 1. In step 2, stirring the emulsion in a batch-type stirring tank is thought to suppress partial or total destruction of the emulsion droplets formed in step 1, forming silica capsule particles with dense and strong shells, and increasing the encapsulation rate of the oil agent.

[0054] In step 2, it is preferable to dilute the emulsion obtained in step 1 by adding water, and then form oil-containing silica capsule particles in a batch-type stirring tank. By including this dilution operation, the amount of the oil agent mixed solution to be subjected to the emulsification treatment in step 1 can be reduced, and shear force can be efficiently applied to the oil agent mixed solution, shortening the emulsification time, suppressing partial or total destruction of the emulsified droplets formed in step 1, and increasing the encapsulation rate of the oil agent. The dilution in step 2 is carried out so that the total amount of the oil and silica precursor used in step 1 is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 27 parts by mass or less, relative to 100 parts by mass of the total amount of the diluted emulsion; and from the viewpoint of production efficiency, is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. The dilution ratio is preferably 1.3 times or more, more preferably 1.4 times or more, and even more preferably 1.5 times or more from the viewpoint of increasing the encapsulation rate of the oil solution, and is preferably 3 times or less, more preferably 2 times or less, and more preferably 1.8 times or less from the viewpoint of production efficiency. In the present invention, the "dilution ratio" refers to the mass ratio of the total amount of the emulsion after dilution to the total amount of the emulsion obtained in step 1 that is to be provided to step 2 before dilution [(total amount of emulsion after dilution) / (total amount of emulsion obtained in step 1 that is to be provided to step 2 before dilution)].

[0055] The pH of the emulsion used to form silica capsule particles in step 2 is preferably 3.0 or higher, more preferably 3.3 or higher, and even more preferably 3.5 or higher, from the viewpoint of maintaining a balance between the hydrolysis reaction and polycondensation reaction of the silica precursor, and from the viewpoint of suppressing the formation of a highly hydrophilic sol, promoting the encapsulation of the oil agent, and increasing the encapsulation rate of the oil agent; and is preferably 4.5 or lower, more preferably 4.3 or lower, and even more preferably 4.0 or lower, from the viewpoint of suppressing the simultaneous formation of a silica shell and aggregation of emulsified droplets, and increasing the encapsulation rate of the oil agent.

[0056] In step 2, from the viewpoint of adjusting the emulsion to a desired pH, a pH adjuster may be added to the emulsion obtained in step 1 according to the pH of the emulsion obtained in step 1 to adjust the pH of the emulsion, and then oil-containing silica capsule particles may be formed in a batch-type stirring tank. The pH adjuster can be appropriately selected from acidic and alkaline pH adjusters depending on the pH of the emulsion obtained in step 1. Examples of acidic pH adjusters include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, organic acids such as acetic acid and citric acid, and solutions prepared by adding cation exchange resins to water, ethanol, etc., and preferably at least one selected from hydrochloric acid, sulfuric acid, nitric acid, and citric acid. Examples of alkaline pH adjusters include sodium hydroxide, sodium bicarbonate, potassium hydroxide, ammonium hydroxide, diethanolamine, triethanolamine, and trishydroxymethylaminomethane, and preferably at least one selected from sodium hydroxide and ammonium hydroxide. Furthermore, depending on the type of oil, the pH of the emulsion obtained in step 1 may be lower than the desired value. In such cases, it is preferable to adjust the pH using the alkaline pH adjuster described above.

[0057] The formation of oil-containing silica capsule particles in step 2 is preferably carried out while stirring in a disperser using a stirring blade, from the viewpoint of suppressing partial or total destruction of the emulsified droplets formed in step 1 and increasing the encapsulation rate of the oil. The stirring blade is preferably one or more types selected from a paddle blade, a turbine blade, an anchor blade, a ribbon blade, and a propeller.

[0058] The stirring speed in step 2 is preferably 200 r / min or less, more preferably 100 r / min or less, and even more preferably 90 r / min or less, in terms of suppressing partial or total destruction of the emulsified droplets formed in step 1 and increasing the encapsulation rate of the oil agent, in terms of tip peripheral speed, and is preferably 10 r / min or more, more preferably 15 r / min or more, and even more preferably 20 r / min or more, in terms of obtaining silica capsule particles with a narrow particle size distribution. The liquid temperature in step 2 is preferably 0°C or higher, and preferably 40°C or lower, more preferably 35°C or lower. The stirring time in step 2 varies depending on the production scale, stirring speed, temperature conditions, etc., but is preferably 6 hours or more, more preferably 12 hours or more, even more preferably 18 hours or more, and is preferably 48 hours or less, more preferably 36 hours or less, even more preferably 30 hours or less.

[0059] In step 2, from the viewpoint of increasing the encapsulation rate of the oil agent, after forming oil agent-containing silica capsule particles (in this case, the oil agent-containing silica capsule particles are also referred to as "oil agent-containing silica capsule particles (1)") using the emulsion obtained in step 1, a silica precursor may be further added to form oil agent-containing silica capsule particles. This forms a second shell that encapsulates the first shell of the oil agent-containing silica capsule particles (1), making the shell of the obtained oil agent-containing silica capsule particles denser and stronger.

[0060] The silica precursor used when a silica precursor is further added in step 2 preferably contains a tetraalkoxysilane, more preferably a tetraalkoxysilane having an alkoxy group having from 1 to 4 carbon atoms, similar to the silica precursor described above, from the viewpoint of accelerating the sol-gel reaction and increasing the encapsulation rate of the oil, even more preferably one or more selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane, even more preferably one or more selected from tetramethoxysilane and tetraethoxysilane, and even more preferably tetraethoxysilane. When the silica precursor contains a tetraalkoxysilane, the content of the tetraalkoxysilane in the silica precursor is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less.

[0061] In order to increase the encapsulation rate of the oil agent, when a silica precursor is further added in step 2, the amount of the silica precursor used is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, relative to 100 parts by mass of the oil agent used in step 1.

[0062] When a silica precursor is further added in step 2, the preferred ranges of the stirring speed, liquid temperature, and stirring time in the formation of the second shell in step 2 are the same as the preferred ranges of the stirring speed, liquid temperature, and stirring time in the formation of the first shell of the oil-containing silica capsule particles (1) described above.

[0063] The oil-containing silica capsule particles obtained by the manufacturing method of the present invention are preferably obtained as an aqueous dispersion in which the oil-containing silica capsule particles are dispersed in water.Depending on the application, the aqueous dispersion can be used as it is, but in some cases, the oil-containing silica capsule particles can be separated and used.As the separation method, filtration method, centrifugation method, etc. can be adopted. The oil-containing silica capsule aqueous dispersion obtained by the production method of the present invention may further contain other components, such as a pH adjuster, a dye, a preservative, an antifoaming agent, an antioxidant, an ultraviolet absorber, a shell surface modifier, a dispersant, an inorganic salt, a thickener, a deposition aid, or a rheology adjuster, as needed. The median diameter D of the oil-containing silica capsule particles according to the present invention 50 is preferably 0.1 μm or more, more preferably 0.3 μm or more, even more preferably 0.5 μm or more, even more preferably 0.7 μm or more, and even more preferably 1.0 μm or more, from the viewpoint of reducing the specific surface area relative to the environment outside the silica capsule particles and improving the retention of the oil agent, and is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and even more preferably 3 μm or less, from the viewpoint of the dispersion stability of the silica capsule particles. Median diameter D of oil-containing silica capsule particles 50 can be measured by the method described in the Examples.

[0064] The oil-containing silica capsule particles according to the present invention can be used in a variety of applications, including cosmetics such as emulsions, cosmetic liquids, lotions, beauty serums, creams, gel preparations, hair treatment agents, and quasi-drugs; textile treatment agents such as detergents, fabric softeners, and anti-wrinkle sprays; sanitary products such as disposable diapers; and fragrances. The oil-containing silica capsule particles according to the present invention can be incorporated into compositions such as detergent compositions, fabric treatment compositions, cosmetic compositions, fragrance compositions, deodorant compositions, etc. The composition is preferably one or more selected from detergent compositions such as powder detergent compositions and liquid detergent compositions; and fabric treatment compositions such as softener compositions, more preferably a fabric treatment composition, and even more preferably a softener composition.

[0065] In relation to the above-mentioned embodiment, the present invention further discloses the following method for producing oil-containing silica capsule particles. <1> A method for producing oil-containing silica capsule particles having a core containing an oil and a shell containing silica as a constituent component, comprising: Step 1: Emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor in an in-line emulsifying disperser to obtain an emulsion; and Step 2: Using the emulsion obtained in Step 1, a method for producing oil-containing silica capsule particles is provided. <2> The reaction rate of the silica precursor in the emulsion obtained in step 1 is 0% or more and 80% or less. <1> The manufacturing method described in <3> The reaction rate of the silica precursor in the emulsion obtained in step 1 is 0% or more and 60% or less. <1> or <2> The manufacturing method described in <4> The reaction rate of the silica precursor in the emulsion obtained in step 1 is 0% or more and 55% or less. <1> ~ <3> 1. The manufacturing method according to any one of the preceding claims. <5> The reaction rate of the silica precursor in the emulsion obtained in step 1 is 0% or more and 50% or less. <1> ~ <4> 1. The manufacturing method according to any one of the preceding claims. <6> The in-line emulsifying disperser used in step 1 has a rotor and a stator. <1> ~ <5> 1. The manufacturing method according to any one of the preceding claims. <7> The in-line emulsifying and dispersing machine used in step 1 is a Cavitron or Milder. <1> ~ <6> 1. The manufacturing method according to any one of the preceding claims. <8> In the emulsification step 1, the rotor rotation energy Q per volume of the emulsification dispersion chamber of the in-line emulsification dispersion machine is 1 x 107 W / m 3 More than 1×10 12 W / m 3 Below is the <1> ~ <7> 1. The manufacturing method according to any one of the preceding claims. <9> In the emulsification step 1, the rotor rotation energy Q' per volume of the emulsification dispersion chamber of the in-line emulsification dispersion machine is 1 x 10 6 W·h / m 3 More than 1×10 12 W·h / m 3 Below is the <1> ~ <8> 1. The manufacturing method according to any one of the preceding claims. <10> In the emulsification step 1, the rotor rotation energy Q'' per volume of the emulsification dispersion chamber of the in-line emulsification dispersion machine and the amount of oil dispersion is 1 x 10 4 W·h / (m 3 ·kg) or more 1×10 12 W·h / (m 3 kg) or less, <1> ~ <9> 1. The manufacturing method according to any one of the preceding claims. <11> In the emulsification of step 1, the processing flow rate of the in-line emulsifying disperser is 0.1 L / min or more and 1000 L / min or less; <1> ~ <10> 1. The manufacturing method according to any one of the preceding claims. <12> The outermost peripheral speed of the rotor of the in-line emulsifying disperser is 3 m / s or more and 50 m / s or less. <1> ~ <11> 1. The manufacturing method according to any one of the preceding claims. <13> The outermost peripheral speed of the rotor of the in-line emulsifying disperser is 5 m / s or more and 45 m / s or less. <1> ~ <12> 1. The manufacturing method according to any one of the preceding claims. <14> The amount of oil mixture used in step 1 is 100 kg or more. <1> ~ <13> 1. The manufacturing method according to any one of the preceding claims. <15> The amount of oil mixture used in step 1 is 300 kg or more and 100,000 kg or less. <1> ~ <14> 1. The manufacturing method according to any one of the preceding claims. <16> The amount of oil mixture used in step 1 is 500 kg or more and 100,000 kg or less. <1> ~ <15> 1. The manufacturing method according to any one of the preceding claims. <17> The amount of oil mixture used in step 1 is 1,000 kg or more and 100,000 kg or less. <1> ~ <16> 1. The manufacturing method according to any one of the preceding claims. <18> The emulsification time in step 1 is 12 hours or less. <1> ~ <17> 1. The manufacturing method according to any one of the preceding claims. <19> The emulsification time in step 1 is 0.1 hours or more and 10 hours or less. <1> ~ <18> 1. The manufacturing method according to any one of the preceding claims. <20> The emulsification time in step 1 is 0.1 hours or more and 8 hours or less. <1> ~ <19> 1. The manufacturing method according to any one of the preceding claims. <21> The emulsification time in step 1 is 0.1 hours or more and 6.5 hours or less. <1> ~ <20> 1. The manufacturing method according to any one of the preceding claims. <22> The emulsification time in step 1 is 0.1 hours or more and 6 hours or less. <1> ~ <21> 1. The manufacturing method according to any one of the preceding claims. <23> The temperature of the oil mixture used for emulsification in step 1 is 0°C or higher and 50°C or lower. <1> ~ <22> 1. The manufacturing method according to any one of the preceding claims. <24> The liquid temperature of the oil mixture used for emulsification in step 1 is 0°C or higher and 40°C or lower. <1> ~ <23> 1. The manufacturing method according to any one of the preceding claims. <25> The liquid temperature of the oil mixture used for emulsification in step 1 is 0°C or higher and 35°C or lower. <1> ~ <24> 1. The manufacturing method according to any one of the preceding claims. <26> The silica precursor comprises a tetraalkoxysilane. <1> ~ <25> 1. A method for producing oil-containing silica capsule particles according to any one of the preceding claims. <27> The silica precursor is a tetraalkoxysilane having an alkoxy group having 1 to 4 carbon atoms. <1> ~ <26> 1. The manufacturing method according to any one of the preceding claims. <28> The silica precursor is at least one selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane. <1> ~ <27> 1. The manufacturing method according to any one of the preceding claims. <29> In step 2, a pH adjuster is added to the emulsion obtained in step 1 to adjust the pH of the emulsion to 4.5 or less, and then oil-containing silica capsule particles are formed in a batch-type stirring tank. <1> ~ <28> 1. The manufacturing method according to any one of the preceding claims. <30> The pH of the emulsion is 3.0 or more and 4.5 or less. <29> The manufacturing method described in <31> The pH of the emulsion is 3.3 or more and 4.3 or less. <29> or <30> The manufacturing method described in <32> In step 2, the emulsion obtained in step 1 is diluted with water, and then oil-containing silica capsule particles are formed in a batch-type stirring tank. <1> ~ <31> 1. The manufacturing method according to any one of the preceding claims. <33> The dilution in step 2 is carried out so that the total amount of the oil agent and the silica precursor used in step 1 is 35 parts by mass or less relative to 100 parts by mass of the total amount of the diluted emulsion. <32> The manufacturing method described in <34> the mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing a surfactant and water to the oil phase component containing an oil and a silica precursor in the oil agent mixture used in step 1 is 50 / 50 or more and 99 / 1 or less; <1> ~ <33> 1. The manufacturing method according to any one of the preceding claims. <35> the mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing a surfactant and water to the oil phase component containing an oil agent and a silica precursor in the oil agent mixture used in step 1 is 53 / 47 or more and 90 / 10 or less; <1> ~ <34> 1. The manufacturing method according to any one of the preceding claims. <36> The emulsification in step 1 is carried out in an external circulation manner using the in-line emulsifying disperser. <1> ~ <35> 1. The manufacturing method according to any one of the preceding claims. <37> The emulsification in step 1 is carried out by mixing a surfactant, water, an oil agent, and a silica precursor in-line to prepare the oil agent mixture, and then supplying the oil agent mixture to the in-line emulsifying disperser. <1> ~ <35> 1. The manufacturing method according to any one of the preceding claims. <38> The number of passes of the in-line emulsifying disperser in step 1 is 1 or more and 100,000 or less. <36> or <37> The manufacturing method described in <39> The number of passes of the in-line emulsifying disperser in step 1 is 1 or more and 10,000 or less. <36> ~ <38> 1. The manufacturing method according to any one of the preceding claims. <40> The number of passes of the in-line emulsifying disperser in step 1 is 2 or more and 5,000 or less. <36> ~ <39> 1. The manufacturing method according to any one of the preceding claims. <41> The number of passes of the in-line emulsifying disperser in step 1 is 3 or more and 3,000 or less, <36> ~ <40> 1. The manufacturing method according to any one of the preceding claims. <42> The median diameter D of the emulsion droplets obtained in step 1 50 is 10 μm or less, <1> ~ <41> 1. The manufacturing method according to any one of the preceding claims. <43> The median diameter D of the emulsion droplets obtained in step 1 50 is 0.1 μm or more and 7 μm or less, <1> ~ <42> 1. The manufacturing method according to any one of the preceding claims. <44> The median diameter D of the emulsion droplets obtained in step 1 50 is 0.3 μm or more and 5 μm or less, <1> ~ <43> 1. The manufacturing method according to any one of the preceding claims. <45> The median diameter D of the emulsion droplets obtained in step 1 50 is 0.5 μm or more and 3 μm or less, <1> ~ <44> 1. The manufacturing method according to any one of the preceding claims. <46> In step 2, a disperser using an agitator blade is used. <1> ~ <45> 1. The manufacturing method according to any one of the preceding claims. <47> The stirring blade is one or more selected from a paddle blade, a turbine blade, an anchor blade, a ribbon blade, and a propeller. <46> The manufacturing method described in <48> The stirring speed in step 2 is 10 r / min or more and 200 r / min or less; <46> or <47> 1. The manufacturing method according to any one of the preceding claims. <49> The stirring speed in step 2 is 15 r / min or more and 100 r / min or less; <46> ~ <48> 1. The manufacturing method according to any one of the preceding claims. <50> The stirring speed in step 2 is 20 r / min or more and 90 r / min or less; <46> ~ <49> 1. The manufacturing method according to any one of the preceding claims. [Example]

[0066] The various measurements and calculations used in the examples were carried out by the following methods.

[0067] [Median diameter D 50 ] Median diameter of emulsion droplets D 50 and the median diameter D of the oil-containing silica capsule particles 50was measured using a laser diffraction / scattering particle size distribution analyzer "LA-960" (trade name, manufactured by Horiba, Ltd.). A flow cell was used for the measurement, and the medium was water, with the refractive index of the dispersoid set to 1.45-0i. An emulsion or a water dispersion containing oil-containing silica capsule particles was added to the flow cell, and measurements were carried out at a concentration where the transmittance was around 90%, and the median diameter D 50 asked for.

[0068] [Silica precursor reaction rate] 100 mg of the oil solution mixture to be emulsified in step 1 was diluted with 10 g of methanol containing dodecane as an internal standard at a concentration of 10 μg / mL, and then this diluted solution was measured using gas chromatography to determine the amount β of silica precursor in 100 mg of the oil solution mixture. Next, 100 mg of the emulsion obtained in step 1 was diluted with 10 g of methanol containing 10 μg / mL of dodecane as an internal standard, and the diluted solution was measured using gas chromatography to determine the amount of unreacted silica precursor α contained in 100 mg of the emulsion. The reaction rate of the silica precursor was calculated using the following formula. Reaction rate of silica precursor (%) = 100 - [(amount of unreacted silica precursor contained in 100 mg of emulsion α) / (amount of silica precursor contained in 100 mg of oil mixture β)] × 100

[0069] <Model Fragrance> The oil to be encapsulated in the silica capsule particles was model fragrance A (volume average cLogP: 3.7, specific gravity: 0.96) having the composition shown in Table 1. The volume average cLogP value of the model fragrance was calculated as the sum of the cLogP values ​​of the fragrance components contained in the model fragrance multiplied by their volume ratios in the model fragrance.

[0070] [Table 1]

[0071] Example 1 (Process 1) In a 300 L spherical-bottomed cylindrical stirring vessel (inner diameter 0.70 m) equipped with a 45° inclined paddle blade (blade diameter 0.35 m), 0.7 kg of Coatamine 60W (trade name, manufactured by Kao Corporation; cetyltrimethylammonium chloride, active ingredient 30% by mass) and 89.4 kg of ion-exchanged water were mixed at a temperature of 15°C and a stirring speed of 80 r / min for 10 minutes to prepare an aqueous phase component. To this aqueous phase component was added an oil phase component prepared by premixing 47.9 kg of model fragrance A as an oil agent and 12.0 kg of tetraethoxysilane (hereinafter also referred to as "TEOS") as a silica precursor in a 200 L drum, to obtain an oil agent mixture. 150.0 kg of the obtained oil solution mixture was emulsified by circulating and mixing the mixture at a temperature of 15°C using the paddle impeller at a stirring speed of 80 r / min and an air-driven diaphragm pump at a flow rate of 40 L / min, while using an in-line emulsifying disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 40 m / s for 20 minutes using an external circulation system, to obtain an emulsion. The median diameter D of the emulsified droplets of the obtained emulsion was 50 The reaction rates of the silica precursor and the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted with 89.4 kg of ion-exchanged water, and a 1% by mass aqueous solution of sulfuric acid was added as a pH adjuster to adjust the pH to 3.7. The liquid temperature was then raised to and maintained at 30°C, and the mixture was stirred in the stirring tank using the paddle impeller at 80 r / min for 24 hours to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2. In Example 1, the time required to produce 100 kg of emulsion was 0.2 hours as an index of emulsion productivity. The shorter this time, the better the emulsion productivity.

[0072] Example 2 (Process 1) 6.5m internal volume with 45° inclined paddle blades (blade diameter 1.3m) 3In a spherical-bottom cylindrical stirring tank (inner diameter 1.9 m), 6.9 kg of Coatamine 60W and 879.1 kg of ion-exchanged water were mixed at a temperature of 15°C and a stirring speed of 35 r / min for 10 minutes to prepare an aqueous phase component. 471.0 kg of model fragrance A as an oil and 118.0 kg of tetraethoxysilane as a silica precursor were added to this aqueous phase component, and the resulting mixture was mixed in a volume of 6.5 m. 3 The oil phase components that had been premixed in a cylindrical tank with a spherical bottom were added to obtain an oil agent mixture. 1475.0 kg of the obtained oil solution mixture was emulsified by circulating and mixing at a temperature of 15°C using the paddle impeller at a stirring speed of 35 r / min and an air-driven diaphragm pump at a flow rate of 50 L / min, while using an in-line emulsifying disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 40 m / s for 150 minutes using an external circulation system, to obtain an emulsion. The median diameter D of the emulsified droplets of the obtained emulsion was 50 The reaction rates of the silica precursor and the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted with 879.1 kg of ion-exchanged water, and a 1% by mass aqueous solution of sulfuric acid was added as a pH adjuster to adjust the pH to 3.7. The liquid temperature was then raised to and maintained at 30°C, and the mixture was stirred in the stirring tank using the paddle impeller at 35 r / min for 24 hours to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2. In Example 2, the time required to produce 100 kg of emulsion was 0.2 hours as an index of emulsification productivity.

[0073] Example 3 (Process 1) 15m internal volume with 45° inclined paddle blades (blade diameter 1.9m) 3 In a spherical-bottom cylindrical stirring tank (inner diameter 2.5 m), 42.2 kg of Coatamine 60W and 5384.3 kg of ion-exchanged water were mixed at a temperature of 15°C and a stirring speed of 27 r / min for 10 minutes to prepare an aqueous phase component. 2884.9 kg of model fragrance A as an oil agent and 722.7 kg of tetraethoxysilane as a silica precursor were added to this aqueous phase component, and the resulting mixture was mixed in a 15 m3 tank. 3The oil phase components prepared by premixing in a cylindrical tank with a spherical bottom were added to obtain an oil solution mixture. 9034.0 kg of the obtained oil solution mixture was emulsified by circulating and mixing at a temperature of 15°C using the paddle impeller at a stirring speed of 27 r / min and an air-driven diaphragm pump at a flow rate of 300 L / min, while using an in-line emulsifying disperser (product name "Cavitron CD1030", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 23 m / s for 140 minutes using an external circulation system, to obtain an emulsion. The median diameter D of the emulsified droplets of the obtained emulsion was 50 The reaction rates of the silica precursor and the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted with 5,384.3 kg of ion-exchanged water, and a 1% by mass aqueous solution of sulfuric acid was added as a pH adjuster to adjust the pH to 3.7. The liquid temperature was then raised to and maintained at 30°C, and the mixture was stirred in the stirring tank using the paddle impeller at 27 r / min for 24 hours to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2. In Example 3, the time required to produce 100 kg of emulsion was 0.03 hours as an index of emulsification productivity.

[0074] Example 4 (Process 1) In a 5L spherical-bottomed cylindrical stirring vessel equipped with a 45° inclined paddle blade (blade diameter 0.35m), 9.3g of Coatamine 60W and 1192.0g of ion-exchanged water were mixed at a temperature of 15°C and a stirring speed of 80 r / min for 10 minutes to prepare an aqueous phase component. To this aqueous phase component was added an oil phase component that had been prepared by pre-mixing 638.7g of model fragrance A as an oil agent and 160.0g of tetraethoxysilane as a silica precursor in a 2L plastic container, to obtain an oil agent mixture. 2 kg of the obtained oil solution mixture was emulsified by circulating it for 3 hours and 59 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 5 m / s, while using the paddle impeller to stir at a rotation speed of 27 r / min and an air-driven diaphragm pump at a flow rate of 7 L / min at a temperature of 15°C. Subsequently, the mixture was circulated for 1 minute at a rotor's outermost peripheral speed of 23 m / s to obtain an emulsion. The median diameter D of the emulsified particles of the obtained emulsion was 50 The reaction rates of the silica precursor and the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted with 1192.0 g of ion-exchanged water, and a 1% by mass aqueous solution of sulfuric acid was added as a pH adjuster to adjust the pH to 3.7. The liquid temperature was then raised to and maintained at 30°C, and the mixture was stirred in the stirring tank using the paddle impeller at 27 r / min for 24 hours to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2.

[0075] Example 5 In step 1 of Example 4, an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2 was obtained in the same manner as in Example 4, except that in step 1 of Example 4, the mixture was emulsified by circulating it for 5 hours and 59 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 5 m / s using an external circulation system, and then by circulating it for 1 minute at a rotor's outermost peripheral speed of 23 m / s.

[0076] Example 6 An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 4, except that in step 1 of Example 4, emulsification was carried out at a liquid temperature of the oil mixed solution of 30°C.

[0077] Example 7 An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 5, except that in step 1 of Example 5, emulsification was carried out at a liquid temperature of the oil mixed solution of 30°C.

[0078] Example 8 An aqueous dispersion containing oil-containing silica capsule particles was obtained in the same manner as in Example 5, except that in step 1 of Example 5, the mixture was emulsified by external circulation for 9 hours and 59 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) set at a rotor outermost peripheral speed of 5 m / s, and then circulated for 1 minute at a rotor outermost peripheral speed of 23 m / s.

[0079] Example 9 In step 1 of Example 7, an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2 was obtained in the same manner as in Example 7, except that in step 1 of Example 7, the mixture was emulsified by circulating it for 6 hours and 59 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 5 m / s, followed by circulating it for 1 minute at a rotor's outermost peripheral speed of 23 m / s.

[0080] Example 10 In step 1 of Example 4, 2 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes, and then the pre-emulsified liquid obtained was emulsified using a "one-pass method" in which the obtained pre-emulsified liquid was passed only once through an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with a rotor outermost peripheral speed of 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 4, except that

[0081] Example 11 In step 1 of Example 1, 150.0 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 80 r / min for 10 minutes, and then the resulting pre-emulsion was emulsified using a "one-pass method" in which the resulting pre-emulsion was passed only once through an in-line emulsifying disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) with a rotor outermost peripheral speed of 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 1, except for this.

[0082] Example 12 In step 1 of Example 3, 9034.0 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle blade (blade diameter 1.9 m) at a stirring speed of 27 r / min for 10 minutes, and then the pre-emulsified liquid obtained was emulsified using a "one-pass method" in which the obtained pre-emulsified liquid was passed only once through an in-line emulsifying disperser (product name "Cavitron CD1030", manufactured by Eurotech Co., Ltd.) at a rotor outermost peripheral speed of 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 3, except that

[0083] Example 13 In step 1 of Example 4, 2 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle impeller (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes, and then, while maintaining the pre-emulsification temperature and stirring speed, the mixture was circulated and mixed at a flow rate of 7 L / min using an air-driven diaphragm pump, and emulsified by external circulation for 1.5 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 4, except that

[0084] Example 14 In step 1 of Example 4, 2 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle impeller (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes, and then, while maintaining the pre-emulsification temperature and stirring speed, the mixture was circulated and mixed at a flow rate of 7 L / min using an air-driven diaphragm pump, and emulsified by external circulation for 4 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 4, except that

[0085] Example 15 In step 1 of Example 4, 2 kg of the oil mixture was pre-emulsified by stirring at a temperature of 15°C using a 45° inclined paddle impeller (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes, and then, while maintaining the pre-emulsification temperature and stirring speed, the mixture was circulated and mixed at a flow rate of 7 L / min using an air-driven diaphragm pump, and emulsified by external circulation for 12.5 minutes using an in-line emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the rotor's outermost peripheral speed set to 40 m / s. An aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained in the same manner as in Example 4, except that

[0086] The encapsulation rate of the oil agent encapsulated in the oil agent-containing silica capsule particles obtained in the examples was calculated and evaluated by the following method. The results are shown in Table 2. [Oil content] 100 mg of the aqueous dispersion containing the oil-containing silica capsule particles obtained in step 2 was diluted with 10 g of methanol containing dodecane at a concentration of 10 μg / mL as an internal standard, and then ultrasonic waves were applied for 60 minutes using an ultrasonic irradiation device (manufactured by Branson, model "5510") at an output of 180 W and an oscillation frequency of 42 kHz to obtain a diluted solution in which the oil solution inside the silica capsule particles had been eluted. Subsequently, the methyl dihydrojasmonate contained in this diluted solution was measured using gas chromatography, and the amount y of methyl dihydrojasmonate in 100 mg of the aqueous dispersion containing the oil-containing silica capsule particles was determined as the amount of oil solution blended. Separately, 100 mg of the aqueous dispersion containing the oil-containing silica capsule particles obtained in step 2 was diluted with 10 g of ion-exchanged water, and then passed through a membrane filter (manufactured by Millipore Corporation, product name "Omnipore", model number "JAWP04700") to recover the oil-containing silica capsule particles on the membrane filter. The oil-containing silica capsule particles were then washed on the membrane filter with 10 mL of ion-exchanged water and then with 10 mL of hexane. The silica capsule particles were then immersed in 2 mL of acetonitrile containing 10 μg / mL of dodecane as an internal standard. Ultrasonic irradiation was performed for 60 minutes using an ultrasonic irradiation device (manufactured by Branson, model "5510") at an output of 180 W and an oscillation frequency of 42 kHz to elute the oil from the silica capsule particles. This solution was then passed through a membrane filter (manufactured by Toyo Roshi Kaisha, Ltd., product name "DISMIC", model "13JP020AN") again, and the methyl dihydrojasmonate contained in this solution was measured using gas chromatography, and the amount of methyl dihydrojasmonate encapsulated in the silica capsule particles was determined as x. The encapsulation rate of the oil was calculated using the following formula: Encapsulation rate of oil (%) = {(amount of methyl dihydrojasmonate encapsulated in oil-containing silica capsule particles in 100 mg of aqueous dispersion containing oil-containing silica capsule particles x) / (amount of methyl dihydrojasmonate in 100 mg of aqueous dispersion containing oil-containing silica capsule particles y)} × 100

[0087] [Table 2]

[0088] From Table 2, it can be seen that the method of the example has a high encapsulation rate of the oil agent. Furthermore, in Examples 1 to 3, 11, and 12, although a large amount of oil agent mixture was used in step 1, the time required to produce 100 kg of emulsion was short, as described above, demonstrating excellent emulsification productivity. [Industrial Applicability]

[0089] According to the present invention, it is possible to produce oil-containing silica capsule particles having a high encapsulation rate of oil. Furthermore, because the present invention has high emulsification productivity, it is useful as a method for producing oil-containing silica capsule particles on an industrial scale using a large amount of an oil mixture.

Claims

1. A method for producing an oil-containing silica capsule particle having a core containing an oil and a shell containing silica as a constituent component, comprising the steps of: Step 1: A step of emulsifying an oil solution mixture containing a surfactant, water, an oil solution, and a silica precursor in an in-line emulsifying disperser to obtain an emulsion; and Step 2: forming oil-containing silica capsule particles in a batch-type stirring tank using the emulsion obtained in step 1.

2. 2. The method for producing oil-containing silica capsule particles according to claim 1, wherein the reaction rate of the silica precursor in the emulsion obtained in step 1 is 80% or less.

3. 3. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the in-line emulsifying and dispersing machine used in step 1 has a rotor and a stator.

4. In the emulsification in step 1, the rotor rotation energy Q″ per the volume of the emulsification dispersion chamber of the in-line emulsification disperser and the amount of the oil dispersion is 1×10 4 W h / (m 3 4. The method for producing oil-containing silica capsule particles according to claim 3, wherein the oil content is 1.0 kg or more.

5. 3. The method for producing oil-containing silica capsule particles according to claim 1, wherein the amount of the oil mixture used in step 1 is 100 kg or more.

6. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the emulsification time in step 1 is 12 hours or less.

7. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the silica precursor comprises tetraalkoxysilane.

8. 3. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein in step 2, a pH adjuster is added to the emulsion obtained in step 1 to adjust the pH of the emulsion to 4.5 or less, and then the oil-containing silica capsule particles are formed in a batch-type stirring tank.

9. 3. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein in step 2, the emulsion obtained in step 1 is diluted by adding water, and then the oil-containing silica capsule particles are formed in a batch-type stirring tank.

10. The method for producing oil-containing silica capsule particles according to claim 9, wherein the dilution in step 2 is carried out so that the total amount of the oil and silica precursor used in step 1 is 35 parts by mass or less relative to a total amount of 100 parts by mass of the diluted emulsion.

11. 3. The method for producing oil-containing silica capsule particles according to claim 1, wherein the mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing a surfactant and water to the oil phase component containing an oil and a silica precursor in the oil agent mixture used in step 1 is 50 / 50 or more and 99 / 1 or less.

12. 3. The method for producing oil-containing silica capsule particles according to claim 1, wherein the emulsification in step 1 is carried out in an external circulation manner using the in-line emulsifying disperser.

13. 3. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the emulsification in step 1 is carried out by mixing a surfactant, water, an oil, and a silica precursor in-line to prepare the oil-agent mixed solution, and then supplying the oil-agent mixed solution to the in-line emulsifying disperser.

14. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the number of passes through the in-line emulsifying disperser in step 1 is one or more.

15. Median diameter D of the emulsion droplets of the emulsion obtained in step 1 50 The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the diameter of said capsule particles is 10 μm or less.

16. The method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein a dispersing machine using an agitating blade is used in step 2.

17. 3. The method for producing oil-containing silica capsule particles according to claim 1, wherein the reaction rate of the silica precursor in the emulsion obtained in step 1 is 55% or less.