Method for manufacturing oil-containing silica capsule particles

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 silica capsule particles containing an oil agent.

Background Art

[0002] Conventionally, attempts have been made to sustain the effects by incorporating silica capsule particles containing an oil agent obtained by encapsulating an oil agent such as a fragrance or a medicinal ingredient into the silica capsule particles in a product. In particular, fiber treatment products, cosmetics, detergents, etc. are one of the important performances to impart a fragrance to clothes and the body, and products with high fragrance persistence are demanded. In such a situation, studies have been conducted on the synthesis of silica capsule particles containing an oil agent by the sol-gel method. 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 fine particles and one or more oil-soluble liquids inside the shell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] The inventors have found that the above problem can be solved in the production of silica capsule particles containing an oil agent by emulsifying the oil agent in an in-line emulsifying and dispersing machine and then forming the silica capsule particles containing the oil agent in a batch-type stirring tank using the emulsified liquid. In other words, the present invention is a method for producing oil-containing silica capsule particles having an oil-containing core and a shell composed of silica. Step 1: A step of emulsifying an oil mixture containing a surfactant, water, oil, and silica precursor using an in-line emulsifier / disperser to obtain an emulsion, and, The present invention provides a method for producing oil-containing silica capsule particles, comprising the step of forming oil-containing silica capsule particles in a batch-type stirring tank using the emulsified liquid obtained in step 1. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a method for producing oil-containing silica capsule particles with a high oil encapsulation rate. [Modes for carrying out the invention]

[0007] [Method for manufacturing oil-containing silica capsule particles] The present invention provides a method for producing oil-containing silica capsule particles (hereinafter also simply referred to as "silica capsule particles") having a core containing an oil and a shell composed of silica. Step 1: A step of emulsifying an oil mixture containing a surfactant, water, oil, and silica precursor using an in-line emulsifier / disperser to obtain an emulsion, and, The method includes step 2: forming oil-containing silica capsule particles in a batch-type stirring tank using the emulsified liquid obtained in step 1.

[0008] In this invention, "reaction rate of silica precursor" refers to the proportion of silica precursor that has reacted, even partially, in the emulsified liquid. For example, when tetraalkoxysilane is used as the silica precursor, the reaction rate is calculated assuming that the tetraalkoxysilane that has been partially hydrolyzed has reacted. The method for calculating the reaction rate of silica precursor will be specifically described in the examples. Furthermore, in this invention, "oil encapsulation rate" refers to the ratio of the amount of oil encapsulated in the silica capsule particles to the total amount of oil blended, and is specifically measured and calculated by the method described in the examples.

[0009] According to the present invention, it is possible to manufacture oil-containing silica capsule particles with a high oil encapsulation rate. The reason for this is not entirely clear, but it is thought to be as follows. In the present invention, in step 1, an oil mixture is emulsified in an inline 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-containing silica capsule particles. One possible installation configuration for the inline emulsifier / disperser used in step 1 is to install the inline emulsifier / disperser outside the storage tank that stores the oil mixture. In this configuration, the oil mixture can be supplied from the storage tank to the inline emulsifier / disperser, and the oil mixture can be emulsified in the emulsifier / disperser chamber. Alternatively, another possible installation configuration for the inline emulsifier / disperser used in step 1 is to provide an inline mixing unit that mixes the surfactant, water, oil, and silica precursor in line, and to install the inline emulsifier / disperser on the line from the mixing unit. In this configuration, the oil mixture can be supplied from the inline mixing unit to the inline emulsifier / disperser, and after emulsification of the oil mixture in the emulsifier / disperser chamber, the emulsified liquid can be supplied to the storage tank. In either configuration, since the volume of the emulsifier / disperser chamber is smaller than that of the storage tank, shear force can be efficiently applied to the oil mixture. By including such step 1, even when using a large amount of oil mixture, the emulsification of the oil mixture can proceed faster than the sol-gel reaction of the silica precursor (reaction of the silica precursor), allowing for the rapid acquisition of an emulsified solution. This is thought to suppress the formation of a shell during emulsification and prevent the shell from breaking due to the application of shear force. Then, in step 2, by subjecting the emulsified liquid obtained in step 1 to a sol-gel reaction in a batch-type stirring tank, it is believed that partial or complete destruction of the emulsion droplets is suppressed, resulting in the formation of silica capsule particles with dense and strong shells, and thus increasing the encapsulation rate of the oil. Here, "sol-gel reaction" refers to the reaction in which a silica precursor undergoes hydrolysis and polycondensation reactions to form silica, which is a component of the shell of an oil-containing silica capsule particle, through sol and gel states. An example of a sol-gel reaction is the reaction in which a tetraalkoxysilane is hydrolyzed as a silica precursor, the silanol compound generates a siloxane oligomer through de-alcoholization condensation and dehydration condensation reactions, and silica is formed by further dehydration condensation reactions.

[0010] <Process 1> Step 1 is a process in which an oil mixture containing a surfactant, water, an oil agent, and a silica precursor is emulsified using an in-line emulsifying and dispersing machine to obtain an emulsion. The oil mixture used in step 1 consists of an aqueous phase component containing a surfactant and water, and an oil phase component containing an oil and a silica precursor.

[0011] (Oil mixture) [Surfactants] The surfactant used in step 1 is preferably a cationic surfactant from the viewpoint of increasing the encapsulation rate of the oil. Examples of cationic surfactants include alkylamine salts and alkyl quaternary ammonium salts. The number of carbon atoms in the alkyl group of alkylamine salts and alkyl quaternary ammonium salts is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and 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 alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium 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 surfactant can be used individually or in combination of two or more types.

[0013] The cationic surfactant is preferably a quaternary ammonium salt, more preferably an alkyltrimethylammonium salt having an alkyl group with 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, and 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, based on 100 parts by mass of the oil used in step 1.

[0015] 〔water〕 For the water used in step 1, it is preferable to use one or more types selected from, for example, ion-exchanged water and distilled water.

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

[0017] [Oils] The oil used in step 1 becomes the encapsulating component of the resulting silica capsule particles. The oily agent is preferably one or more selected from fragrances, fragrance precursors, humectants, antioxidants, antibacterial agents, fertilizers, surface modifiers for fibers, skin, and hair, cooling agents, dyes, pigments, silicones, and oil-soluble polymers; more preferably one or more selected from fragrances, fragrance precursors, humectants, antioxidants, antibacterial agents, fertilizers, and surface modifiers; even more preferably one or more selected from fragrances, fragrance precursors, humectants, and antioxidants; even more preferably one or more selected from fragrances, fragrance precursors, and humectants; and even more preferably one or more selected from fragrances and fragrance precursors. The aforementioned oils can be used individually or in combination of two or more types.

[0018] Examples of the aforementioned fragrance precursors include compounds that release fragrance components in response to water, and compounds that release fragrance components in response to light. Compounds that release fragrance components in reaction with water include silicate ester compounds having an alkoxy component derived from fragrance alcohol, fatty acid ester compounds having an alkoxy component derived from fragrance alcohol, acetal compounds or hemiacetal compounds obtained by the reaction of a carbonyl component derived from a fragrance aldehyde or fragrance ketone with an alcohol compound, Schiff base compounds obtained by the reaction of a carbonyl component derived from a fragrance aldehyde or fragrance ketone with a primary amine compound, and hemiaminal compounds or hydrazone compounds obtained by the reaction of a carbonyl component derived from a fragrance aldehyde or fragrance ketone with a hydrazine compound. Compounds that release fragrance components in response to light include 2-nitrobenzyl ether compounds having an alkoxy component derived from fragrance alcohols, α-ketoester compounds having a carbonyl component derived from fragrance aldehydes or fragrance ketones, and coumaric acid ester compounds having an alkoxy component derived from fragrance alcohols. These fragrance precursors may also be used as polymers, for example, as reaction products between some carboxyl groups of polyacrylic acid and fragrance alcohols.

[0019] The calculated value of the common logarithm "LogP" of the partition coefficient P(n-octanol / water) between n-octanol and water in the aforementioned oil (hereinafter also referred to as the "cLogP value") is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less, from the viewpoint of obtaining a stable emulsion. If the oil is composed of multiple 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 summing them up. By having a cLogP value of 1 or higher for the oil, the encapsulation rate of the oil into the resulting silica capsule particles can be increased during the sol-gel reaction of the silica precursor. Similarly, even if the oil is a fragrance composition composed of multiple fragrance components, the encapsulation rate of the fragrance composition into the resulting silica capsule particles can be increased by having a cLogP value of 1 or higher for the fragrance composition. Here, the cLogP value is "LogP (cLogP)" calculated using the method described in A. Leo Comprehensive Medicinal Chemistry, Vol.4 C. Hansch, PGSammens, JB Taylor and CARamsden, Eds., P.295, Pergamon Press, 1990, and the cLogP value calculated by the program CLOGP v4.01 can be used.

[0020] [Silica precursor] The silica precursor used in step 1 is preferably a tetraalkoxysilane, more preferably a tetraalkoxysilane having an alkoxy group with 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 tetraalkoxysilane, it may also contain trialkoxysilanes such as triethoxysilane and trimethoxysilane, but the tetraalkoxysilane content 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, per 100 parts by mass of oil used in step 1, from the viewpoint of forming a shell that can surround the emulsion droplet containing the oil, and from the viewpoint of suppressing the residue of the silica precursor inside the emulsion droplet in the sol-gel reaction and efficiently promoting the conversion to a shell, it 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, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0022] The oil mixture used in step 1 may contain emulsifying agents, particle size stabilizers, and other oil phase components besides the oil and silica precursor.

[0023] [Emulsifying agent] Preferably, the emulsifying aid is one or more selected from higher aliphatic alcohols having 6 or more carbon atoms, higher fatty acids having 6 or more carbon atoms, monoalkylglyceryl ethers having an alkyl group having 6 or more carbon atoms, and amide compounds having an alkyl group having 8 or more carbon atoms. Because these emulsifying aids have long-chain aliphatic hydrocarbon groups and polar groups, it is thought that they can suppress the reaction of the silica precursor during the emulsification of the oil mixture in step 1, thereby rapidly promoting emulsification and increasing the oil encapsulation rate. The emulsifying agent can be used individually or in combination of two or more types. The molecular weight of the emulsifying agent is preferably 500 or less, more preferably 450 or less, even more preferably 400 or less, even more preferably 350 or less, and preferably 150 or more, from the viewpoint of suppressing the reaction of the silica precursor, rapidly promoting emulsification, and increasing the encapsulation rate of the oil.

[0024] The carbon number of the aforementioned higher aliphatic alcohol is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, even more preferably 14 or more, and preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly proceeding with emulsification, and increasing the encapsulation rate of the oil. From the same viewpoint as described 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 aforementioned higher aliphatic alcohol is preferably solid at room temperature and atmospheric pressure (for example, with a melting point of 30°C or higher). The melting point of the aforementioned higher aliphatic alcohol is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and even more preferably 45°C or higher. Examples of the aforementioned higher aliphatic primary alcohols include 2-ethylhexyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, and oleyl alcohol. Preferably, one or more are selected from 2-ethylhexyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol, more preferably one or more are selected from cetyl alcohol and stearyl alcohol, and even more preferably cetyl alcohol.

[0025] The carbon number of the aforementioned higher fatty acid is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, even more preferably 14 or more, even more preferably 16 or more, and preferably 26 or less, more preferably 22 or less, and even more preferably 20 or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly proceeding with emulsification, and increasing the encapsulation rate of the oil. Examples of the aforementioned higher fatty acids include 2-ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, lanolinic acid, and isostearic acid. 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 monoalkylglyceryl ether is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, even more preferably 16 or more, and preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly proceeding with emulsification, and increasing the encapsulation rate of the oil. 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 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, and preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly proceeding with emulsification, and increasing the encapsulation rate of the oil. The amide compound is preferably an amide compound having an alkyl group derived from a saturated or unsaturated fatty acid. Specifically, examples include lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, and the like.

[0028] The cLogP value of the emulsifying aid is preferably 4 or higher, more preferably 5 or higher, even more preferably 6 or higher, and preferably 10 or lower, more preferably 9 or lower, from the viewpoint of suppressing the reaction of the silica precursor, rapidly promoting emulsification, and increasing the oil content.

[0029] Furthermore, the aforementioned higher fatty acids and higher aliphatic alcohols are considered to have functions not only as emulsifying aids but also as particle size stabilizers that stabilize the particle size of the emulsified droplets. From this viewpoint, the oil mixture used in step 1 preferably contains 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 higher fatty acids having 6 or more carbon atoms, as oil phase components other than the oil and silica precursor.

[0030] If the oil mixture used in step 1 further contains the emulsifying aid as an oil phase component, the amount of the emulsifying aid is 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, and even more preferably 5 parts by mass or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly proceeding with emulsification, and increasing the oil content, per 100 parts by mass of the oil used in step 1.

[0031] [Particle size stabilizer] Examples of particle size stabilizers include fatty acid esters having a total of 6 or more carbon atoms. The particle size stabilizer is thought to contribute to suppressing the destabilization of emulsion droplets by Ostwald aging, in which relatively hydrophilic components in the oil phase of the emulsion droplets molecularly diffuse into the continuous aqueous phase. This suppresses the coarsening of emulsion droplets over time and stabilizes the particle size of the emulsion droplets. Therefore, by using the particle size stabilizer in combination with the emulsifying aid, it is possible to suppress the reaction of the silica precursor, accelerate emulsification, provide a suitable shell formation site as a template for silica capsule particles, and increase the encapsulation rate of the oil. From this viewpoint, the clogP value of the particle size stabilizer is preferably 4 or higher, more preferably 5 or higher, even more preferably 6 or higher, and even more preferably 7 or higher, and preferably 10 or lower, more preferably 9 or lower.

[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 viewpoint of suppressing the reaction of the silica precursor, rapidly promoting emulsification, and increasing the encapsulation rate of the oil. Examples of the fatty acid esters 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, and glycerin fatty acid triesters. Among these, fatty acid monoesters are preferred from the viewpoint of suppressing the reaction of silica precursors, rapidly promoting emulsification, and increasing the encapsulation rate of oil. The fatty acid monoester is preferably composed of 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 aforementioned fatty acid monoesters 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, margadecic acid, stearic acid, oleic acid, linoleic acid, erucic acid, arachidic acid, and behenic acid. Examples of monohydric alcohols 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 aforementioned fatty acid monoesters include cetyl 2-ethylhexanoate, butyl stearate, isopropyl myristate, hexadecyl myristate, 2-octyldodecyl myristate, isopropyl palmitate, hexadecyl palmitate, and 2-ethylhexyl stearate. Among these, isopropyl palmitate is preferred.

[0033] If the oil mixture used in step 1 further contains the particle size stabilizer as an oil phase component, the amount of the particle size stabilizer is 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, and even more preferably 5 parts by mass or less, from the viewpoint of suppressing the reaction of the silica precursor, rapidly promoting emulsification, and increasing the oil encapsulation rate, per 100 parts by mass of the oil used in step 1.

[0034] The mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing the surfactant and water in the oil mixture used in step 1 to the oil phase component containing the oil and silica precursor 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 from the viewpoint of manufacturing efficiency, it is preferably 99 / 1 or less, more preferably 95 / 5 or less, even more preferably 90 / 10 or less, even more preferably 80 / 20 or less, and even more preferably 70 / 30 or less.

[0035] (Emulsification of oil-based mixtures) In step 1, a preferred emulsification method involves mixing pre-prepared aqueous and oil phase components in a storage tank to prepare an oil mixture, and then supplying this mixture to an in-line emulsifying and dispersing machine located outside the storage tank for emulsification. In this method, the order in which the aqueous and oil phase components are added to the storage tank is not particularly limited, but from the viewpoint of ease of manufacture, it is preferable to prepare the aqueous phase component in the storage tank first, and then add the separately prepared oil phase component. The storage tank is preferably equipped with a stirring device having a stirring blade. Examples of agitation blades include paddle blades, turbine blades, anchor blades, ribbon blades, and propellers. In this case, from the viewpoint of manufacturing efficiency, it is preferable to use the batch-type agitator used in step 2 as the storage tank. Alternatively, as another emulsification method in step 1, a preferred method is to prepare an oil mixture by mixing a surfactant, water, oil, and silica precursor in-line, and then supply the oil mixture to an in-line emulsifier / disperser for emulsification. When preparing the oil mixture by mixing in-line, it is preferable to obtain the oil mixture by mixing the aqueous phase component containing the surfactant and water and the oil phase component containing the oil and silica precursor in a single line (in the piping). The aqueous phase component for inline mixing is preferably prepared using a stirring device with agitators. Examples of agitators include those similar to those used in the storage tank described above. The oil phase component for inline mixing may also be prepared using a stirring device with agitators, or it may be prepared by mixing the oil and silica precursor inline. For the above in-line mixing, it is preferable to use an in-line mixer such as a static mixer.

[0036] When preparing the aqueous phase component using the aforementioned 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 account the tip peripheral speed, and from the viewpoint of suppressing temperature rise due to stirring, it is preferably 120 r / min or less, more preferably 100 r / min or less, and even more preferably 90 r / min or less. In this invention, "tip peripheral speed" refers to the peripheral speed of the outer circumference of the largest stirring blade (main stirring blade) in the stirring device when a stirring blade is used. In the preparation of the aqueous phase component using the aforementioned stirring device, the liquid temperature during stirring is preferably 0°C or higher, preferably 40°C or lower, and more preferably 35°C or lower. The stirring time in the preparation of the aqueous phase component using the aforementioned stirring device depends on the scale of production, 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 preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less.

[0037] From the viewpoint of productivity, the amount of 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, even more preferably 500 kg or more, and even more preferably 1,000 kg or more. From the viewpoint of equipment, it is preferably 100,000 kg or less, and more preferably 10,000 kg or less. In this invention, a large amount of oil mixture refers to an amount of oil mixture used in step 1 that is 100 kg or more.

[0038] When preparing the oil mixture in a storage tank, it is preferable that in step 1, the oil mixture in the storage tank is circulated and mixed by the aforementioned stirring blades and then supplied to the inline emulsifier / disperser. The stirring rotation speed at this time 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 account the tip peripheral speed, and from the viewpoint of suppressing temperature rise due to stirring, it is 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 preparing the oil mixture in a storage tank, the oil mixture used in step 1 may be pre-emulsified with the aforementioned stirring blades before being supplied to the inline emulsifier / disperser. The preferred range of stirring rotation speed in this case is the same as the preferred range of stirring rotation speed during the circulation mixing described above. The liquid temperature of the oil mixture used for preliminary emulsification is preferably 0°C or higher, preferably 40°C or lower, and more preferably 35°C or lower. The stirring time during pre-emulsification depends on the scale of production, 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 preferably 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less.

[0040] The emulsification in step 1 is carried out using an in-line emulsifier and disperser, in order to suppress the reaction of the silica precursor, accelerate emulsification, and increase the encapsulation rate of the oil. The emulsification in step 1 may be a "one-pass method" in which the oil mixture is passed through the inline emulsifier / disperser only once, or it may be a "multi-pass method" in which at least a portion or all of the emulsion obtained by passing the oil mixture through the inline emulsifier / disperser is passed through the inline emulsifier / disperser multiple times. One example of a one-pass method is the inline method. Multi-pass methods include "external circulation type," "catchball type," "liquid return type," and "in-line type."

[0041] The external circulation system is a method in which an oil mixture is discharged from a storage tank equipped with an external circulation line that includes an in-line emulsifier / disperser, emulsified by the in-line emulsifier / disperser, and then returned to the storage tank via the external circulation line, thereby circulating the emulsified liquid between the in-line emulsifier / disperser and the storage tank. The catchball method involves installing an in-line emulsifying and dispersing machine between two storage tanks, and using this line to move the emulsified liquid back and forth between the tanks. The liquid return system is a method in which two storage tanks and an in-line emulsifier / disperser are connected by a line so that the liquid circulates between them, and after the entire volume of liquid has passed through the in-line emulsifier / disperser, the liquid is returned to the original storage tank, and this process is repeated. As an in-line method, a preferred method involves mixing a surfactant, water, oil, and silica precursor in-line to prepare an oil mixture, and then supplying the oil mixture to an in-line emulsifier / disperser for emulsification.

[0042] Among these methods, from the viewpoint of suppressing the reaction of the silica precursor, rapidly advancing emulsification, increasing the encapsulation rate of the oil, and ease of equipment design, it is preferable that the emulsification in step 1 be carried out using an in-line emulsifying disperser in an external circulation or in-line manner. In the case of an external circulation system, it is preferable to circulate the emulsified liquid between the inline emulsifier / disperser and a single storage tank via an external circulation line, from the viewpoint of suppressing the reaction of the silica precursor, rapidly promoting emulsification, increasing the encapsulation rate of the oil, and from the viewpoint of ease of equipment design. Even in the case of an external circulation system, the oil mixture can be discharged from the storage tank via an external circulation line, emulsified by an in-line emulsifier / disperser, and then returned to the same storage tank as the original storage tank via the external circulation line, or it can be moved to a different storage tank from the original storage tank via the line. In the case of an in-line system, it is preferable to attach an in-line emulsifying and dispersing machine to the line from the in-line mixing unit, which mixes the surfactant, water, oil, and silica precursor in-line, and to emulsify them using the in-line emulsifying and dispersing machine. In the case of an in-line system, the oil mixture, which has been mixed in-line, only needs to be passed through an in-line emulsifier / disperser at least once. In other words, in the case of an in-line system, the number of passes may be one (single-pass system) or multiple (multi-pass system). In an in-line system, when the oil mixture is passed through the in-line emulsifier / disperser multiple times, it is preferable to store the emulsion obtained by passing the oil mixture discharged from the in-line mixing section through the in-line emulsifier / disperser in a storage tank, connect the storage tank and the in-line emulsifier / disperser with a line so that the liquid circulates, and then pass at least a portion or all of the emulsion through the in-line emulsifier / disperser again. In any of the above methods, two or more inline emulsifying and dispersing machines may be connected together.

[0043] In line emulsifying and dispersing machines preferably have a rotor and a stator, from the viewpoint of efficiently applying shear force to the oil mixture, suppressing the reaction of silica precursors, rapidly promoting emulsification, and increasing the oil encapsulation rate. An emulsifying and 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 and dispersing chamber. In other words, by adjusting the shear speed by varying the clearance between the rotor and the stator and the rotational speed of the rotor, the oil mixture passes between the rotor and stator rotating in the emulsifying and dispersing chamber, thereby applying a shear force to the oil mixture and performing emulsification. Examples of inline emulsifying and dispersing machines include Cavitron (manufactured by Eurotech Co., Ltd.) and Milder (manufactured by Taiheiyo Kiko Co., Ltd.). Among these, Cavitron (manufactured by Eurotech Co., Ltd.) or Milder (manufactured by Taiheiyo Kiko Co., Ltd.) are preferred from the viewpoint of being able to impart the desired shear force to the oil mixture, with Cavitron (manufactured by Eurotech Co., Ltd.) being particularly preferred and is exemplified.

[0044] In the emulsification process of step 1, the shear force applied to the oil mixture is preferably adjusted using the rotational energy Q of the rotor per unit volume of the emulsification and dispersion chamber of the inline emulsification and dispersion machine as an indicator. The rotational energy Q of the rotor per unit volume of the emulsification and dispersion chamber of an inline emulsification and dispersion machine can be calculated based on the following formula (I). Rotational energy Q (W / m 3 ) = [Rotor rotational power P (W)] / [Emulsification and dispersion chamber volume of inline emulsification and dispersion machine (m³) 3 )〕 (I) In equation (I), the rotational power P (W) of the rotor is calculated by the following (experimental equation 1). Rotational power P(W) = n 3 ×d 5 ×ρ (Experimental Formula 1) n: Rotor rotation speed (s -1 ) d: Rotor outer diameter (m) ρ: Density of the oil mixture (kg / m³) 3 ) Here, ρ is 1000 (kg / m 3 Use an approximate value of ). The rotational energy Q preferably satisfies 1×10 7 W / m 3 or more, more preferably 1×10 8 W / m 3 or more, and still more preferably 1×10 9 W / m 3 or more, from the viewpoint of enhancing the shearing effect on the oil agent mixture and suppressing the reaction rate of the silica precursor while quickly producing a fine emulsion with an average particle size of 10 μm or less. Also, from the viewpoint of production efficiency, the rotational energy Q may preferably be 1×10 12 W / m 3 or less.

[0045] In addition, the shearing 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 considering the emulsification time for the rotational energy Q of the rotor per unit volume of the emulsification and dispersion chamber of the in-line emulsification and dispersion machine. The rotational energy Q' is obtained based on the following calculation formula (II). Rotational energy Q' (W·h / m 3 ) = [(Rotational power required for the rotor P (W)) × (Emulsification time (h))] / [Volume of the emulsification and dispersion chamber of the in-line emulsification and 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, an approximate value of 1000 (kg / m 3 ) is used for ρ. The rotational energy Q' preferably satisfies 1×10 6 W·h / m 3 or more, more preferably 1×10 7 W·h / m 3 or more, and still more preferably 1×10 8 W·h / m 3 or more, from the viewpoint of enhancing the shearing effect on the oil agent mixture and suppressing the reaction rate of the silica precursor while quickly producing a fine emulsion with an average particle size of 10 μm or less. Also, from the viewpoint of production efficiency, the rotational energy Q' may preferably be 1×10 12 W·h / m 3 or less.

[0046] Furthermore, when multiple inline emulsifiers and dispersers are used in series, or when an inline emulsifier and disperser equipped with multiple stages of rotors and stators in the emulsifier and disperser chamber, such as the Milder (manufactured by Taiheiyo Kiko Co., Ltd.), the rotational power P(W) of the rotor refers to the sum of the rotational power P(W) calculated for each inline emulsifier and disperser, or the sum of the rotational power P(W) calculated for each stage. Furthermore, if conditions such as the rotor speed are changed during the emulsification process in step 1, the rotational energy Q'(W·h / m) will be reduced. 3 ) is the rotational energy Q'(W·h / m) calculated from each condition and the emulsification time performed under that condition. 3 ) is calculated as the sum.

[0047] Furthermore, the rotational energy Q'(W·h / m) is as described above. 3 The rotational energy Q' (W·h / m²) per kg of oil mixture is obtained by dividing the rotational energy Q' by the amount of oil mixture used in step 1 (kg). 3 )(that is, the rotational energy of the rotor Q'' (W·h / (m) per unit volume of the emulsification dispersion chamber and the amount of oil dispersion) 3 From the viewpoint of enhancing the shear effect on the oil mixture, suppressing the reaction rate of the silica precursor, and rapidly producing a fine emulsion with an average particle size of 10 μm or less, a quantity of 1 × 10 kg is preferably used. 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 It is ≥ 1 kg. Furthermore, from the viewpoint of manufacturing efficiency, the rotational energy Q'' is preferably 1 × 10 12 W·h / (m 3 It may be less than or equal to (kg).

[0048] From the viewpoint of rapidly producing a fine emulsion with an average particle size of 10 μm or less before the reaction of the silica precursor proceeds, the processing flow rate of the inline emulsifier / 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. Also, from the viewpoint of ease of production, the processing flow rate may preferably be 1000 L / min or less.

[0049] The outermost peripheral speed of the rotor of the inline emulsifying disperser is preferably 3 m / s or more, more preferably 5 m / s or more, even more preferably 10 m / s or more, even 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 preferably 50 m / s or less, more preferably 45 m / s or less, from the viewpoint of suppressing the rise in liquid temperature in the emulsifying dispersing chamber.

[0050] When emulsification in step 1 is performed using an in-line emulsifying disperser, the number of passes of 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 in terms of manufacturing efficiency, it is preferably 100,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, even more preferably 3,000 or less, even more preferably 2,000 or less, even more preferably 1,500 or less, and even more preferably 1,300 or less. The number of passes indicates the number of shear cycles the oil mixture undergoes due to the rotor, and is calculated based on the following 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 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 even more preferably 30°C or lower. Furthermore, from the viewpoint of manufacturing efficiency, the liquid temperature of the oil mixture used for emulsification in step 1 may preferably be 0°C or higher. The emulsification time in step 1 can be adjusted as appropriate depending on the scale of production, but is preferably 12 hours or less, more preferably 10 hours or less, even more preferably 8 hours or less, even more preferably 6.5 hours or less, even more preferably 6 hours or less, even more preferably 5 hours or less, and even more preferably 4 hours or less. Furthermore, from the viewpoint of ease of production, it 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, if the amount of oil mixture used in step 1 is 100 kg or more, the emulsification time in step 1 is preferably 12 hours or less, more preferably 10 hours or less, even more preferably 8 hours or less, even more preferably 6.5 hours or less, even more preferably 6 hours or less, even more preferably 5 hours or less, even more preferably 4 hours or less, and even more preferably 3 hours or less, and from the viewpoint of ease of manufacture, it is preferably 0.1 hours or more.

[0052] Median diameter D of the emulsion droplets in the emulsion obtained in step 1 50 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, it 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 the dispersion stability of the resulting silica capsule particles, it 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. The median diameter D of the emulsion droplet 50 This can be measured by the method described in the examples. The reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is preferably 80% or less, more preferably 70% or less, even more preferably 60% or less, even more preferably 55% or less, even more preferably 50% or less, even more preferably 40% or less, even more preferably 35% or less, and even more preferably 30% or less, and 0% or more, and from the viewpoint of ease of manufacture, it 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 in which oil-containing silica capsule particles are formed in a batch-type stirring tank using the emulsified liquid obtained in Step 1. In step 2, by stirring the emulsified liquid in a batch-type stirring tank, it is believed that the partial or complete destruction of the emulsion droplets formed in step 1 can be suppressed, resulting in the formation of silica capsule particles with dense and strong shells, thereby increasing the encapsulation rate of the oil.

[0054] In step 2, it is preferable to add water to the emulsified liquid obtained in step 1 to dilute it, and then form oil-containing silica capsule particles in a batch-type stirring tank. By including this dilution step, the amount of oil mixture subjected to the emulsification process in step 1 can be reduced, shear force can be efficiently applied to the oil mixture, the emulsification time can be shortened, partial or complete destruction of the emulsion droplets formed in step 1 can be suppressed, and the oil encapsulation rate can be increased. The dilution in step 2 is carried out such that the total amount of 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 manufacturing efficiency, 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. From the viewpoint of increasing the oil content, 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, and from the viewpoint of manufacturing efficiency, it is preferably 3 times or less, more preferably 2 times or less, and more preferably 1.8 times or less. In this invention, "dilution ratio" refers to the mass ratio of the total amount of the diluted emulsion to the total amount of the emulsion obtained in step 1 before dilution, which is used in step 2 [(total amount of diluted emulsion) / (total amount of the emulsion obtained in step 1 before dilution, used in step 2)].

[0055] In step 2, the pH of the emulsifying liquid used to form silica capsule particles 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 highly hydrophilic sols, promoting the encapsulation of oil, and increasing the oil encapsulation rate. Furthermore, from the viewpoint of suppressing the simultaneous occurrence of silica shell formation and the aggregation of emulsion droplets and increasing the oil encapsulation rate, the pH is preferably 4.5 or lower, more preferably 4.3 or lower, and even more preferably 4.0 or lower.

[0056] In step 2, from the viewpoint of adjusting the emulsified solution to a desired pH, a pH adjusting agent may be added to the emulsified solution obtained in step 1 according to the pH of the emulsified solution obtained in step 1, and after adjusting the pH of the emulsified solution, oil-containing silica capsule particles may be formed in a batch-type stirring tank. Depending on the pH of the emulsified solution obtained in step 1, an acidic pH adjuster and an alkaline pH adjuster can be appropriately selected and used. Examples of acidic pH adjusting agents include solutions obtained by adding inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, organic acids such as acetic acid and citric acid, and cation exchange resins to water or ethanol, and preferably one or more selected from hydrochloric acid, sulfuric acid, nitric acid, and citric acid. Examples of alkaline pH adjusting agents include sodium hydroxide, sodium bicarbonate, potassium hydroxide, ammonium hydroxide, diethanolamine, triethanolamine, and trishydroxymethylaminomethane, and preferably one or more selected from sodium hydroxide and ammonium hydroxide. Furthermore, depending on the type of oil used, the pH of the emulsified liquid obtained in step 1 may fall below the desired value. In such cases, it is preferable to adjust the pH using the alkaline pH adjusting agent mentioned above.

[0057] In step 2, the formation of oil-containing silica capsule particles is preferably carried out while stirring with a disperser using a stirring blade, from the viewpoint of suppressing the partial or complete destruction of the emulsion droplets formed in step 1 and increasing the oil encapsulation rate. The aforementioned stirring blades are preferably one or more selected from, for example, paddle blades, turbine blades, anchor blades, ribbon blades, and propellers.

[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 tip peripheral speed, from the viewpoint of suppressing partial or total destruction of the emulsion droplets formed in step 1 and increasing the encapsulation rate of the oil, and from the viewpoint of obtaining silica capsule particles with a narrow particle size distribution, it is preferably 10 r / min or more, more preferably 15 r / min or more, and even more preferably 20 r / min or more. The liquid temperature in step 2 is preferably 0°C or higher, preferably 40°C or lower, and more preferably 35°C or lower. The stirring time in step 2 depends on the scale of production, 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 preferably 48 hours or less, more preferably 36 hours or less, and even more preferably 30 hours or less.

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

[0060] In step 2, if a silica precursor is added further, the silica precursor used is preferably a tetraalkoxysilane, more preferably a tetraalkoxysilane having an alkoxy group with 1 to 4 carbon atoms, more preferably one or more selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane, more preferably one or more selected from tetramethoxysilane and tetraethoxysilane, and still more preferably tetraethoxysilane. When the silica precursor contains tetraalkoxysilane, the tetraalkoxysilane content 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] When a silica precursor is further added in step 2, the amount of 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 preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 100 parts by mass or less, with respect to 100 parts by mass or less, from the viewpoint of increasing the encapsulation rate of the oil.

[0062] When a silica precursor is further added in step 2, the preferred ranges for stirring speed, liquid temperature, and stirring time in the second shell formation in step 2 are the same as the preferred ranges for stirring speed, liquid temperature, and stirring time in the first shell formation 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 may be used as is, but in some cases, the oil-containing silica capsule particles may be separated and used. As a separation method, filtration, centrifugation, etc., can be used. The aqueous dispersion of oil-containing silica capsules obtained by the manufacturing method of the present invention may optionally contain other components such as pH adjusters, dyes, preservatives, defoamers, antioxidants, ultraviolet absorbers, shell surface modifiers, dispersants, inorganic salts, thickeners, deposition aids, and rheology modifiers. Median diameter D of oil-containing silica capsule particles according to the present invention 50 From the viewpoint of reducing the specific surface area of ​​the silica capsule particles relative to the environment outside the particles and improving the retention of the oil, it 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 the dispersion stability of the silica capsule particles, it 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. Median diameter D of oil-containing silica capsule particles 50 This 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. For example, the oil-containing silica capsule particles according to the present invention can be suitably used in cosmetics such as lotions, cosmetic liquids, toners, serums, creams, gel formulations, hair treatments, and quasi-drugs; textile treatments such as detergents, fabric softeners, and wrinkle-preventing sprays; sanitary products such as disposable diapers; and fragrances. The oil-containing silica capsule particles according to the present invention can be used by incorporating them into compositions such as detergent compositions, textile treatment compositions, cosmetic compositions, fragrance compositions, and deodorant compositions. The composition is preferably one or more selected from detergent compositions such as powder detergent compositions and liquid detergent compositions; and textile treatment compositions such as fabric softener compositions, more preferably a textile treatment composition, and even more preferably a fabric softener composition.

[0065] With regard to the embodiments described above, 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 an oil-containing core and a shell composed of silica, Step 1: A step of emulsifying an oil mixture containing a surfactant, water, oil, and silica precursor using an in-line emulsifier / disperser to obtain an emulsion, and, A method for producing oil-containing silica capsule particles, comprising: Step 2: Using the emulsified liquid obtained in Step 1, forming oil-containing silica capsule particles in a batch-type stirring tank. <2> The reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is between 0% and 80%. <1> The manufacturing method described above. <3> The reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is 0% or more and 60% or less. <1> or <2> The manufacturing method described above. <4> The reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is between 0% and 55%. <1> ~ <3> A manufacturing method described in any of the following. <5> The reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is between 0% and 50%. <1> ~ <4> A manufacturing method described in any of the following. <6> The in-line emulsifying and dispersing machine used in step 1 has a rotor and a stator. <1> ~ <5> A manufacturing method described in any of the following. <7> The in-line emulsifying and dispersing machine used in step 1 is either a Cavitron or a Milder. <1> ~ <6> A manufacturing method described in any of the following. <8> In the emulsification process of step 1, the rotational energy Q of the rotor per unit volume of the emulsification and dispersion chamber of the inline emulsification and dispersion machine is 1 × 10⁻⁶7 W / m 3 The above 1 x 10 12 W / m 3 The following is: <1> ~ <7> A manufacturing method described in any of the following. <9> In the emulsification process of step 1, the rotational energy Q' of the rotor per unit volume of the emulsification and dispersion chamber of the inline emulsification and dispersion machine is 1 × 10⁻⁶ 6 W·h / m 3 The above 1 x 10 12 W·h / m 3 The following is: <1> ~ <8> A manufacturing method described in any of the following. <10> In the emulsification process of step 1, the rotational energy Q'' of the rotor per unit volume of the emulsification and dispersion chamber and the amount of oil dispersion in the inline emulsification and dispersion machine is 1 × 10⁻⁶ 4 W·h / (m 3 ·kg) or more 1×10 12 W·h / (m 3 It is less than or equal to (kg) <1> ~ <9> A manufacturing method described in any of the following. <11> In the emulsification process of step 1, the processing flow rate of the inline emulsifier / disperser is 0.1 L / min or more and 1000 L / min or less. <1> ~ <10> A manufacturing method described in any of the following. <12> The outermost peripheral speed of the rotor of the inline emulsifying disperser is 3 m / s or more and 50 m / s or less. <1> ~ <11> A manufacturing method described in any of the following. <13> The outermost peripheral speed of the rotor of the inline emulsifying disperser is 5 m / s or more and 45 m / s or less. <1> ~ <12> A manufacturing method described in any of the following. <14> The amount of oil mixture used in step 1 is 100 kg or more. <1> ~ <13> A manufacturing method described in any of the following. <15> The amount of oil mixture used in step 1 is between 300 kg and 100,000 kg. <1> ~ <14> A manufacturing method described in any of the following. <16> The amount of oil mixture used in step 1 is between 500 kg and 100,000 kg. <1> ~ <15> A manufacturing method described in any of the following. <17> The amount of oil mixture used in step 1 is between 1,000 kg and 100,000 kg. <1> ~ <16> A manufacturing method described in any of the following. <18> The emulsification time in step 1 is 12 hours or less. <1> ~ <17> A manufacturing method described in any of the following. <19> The emulsification time in step 1 is between 0.1 hours and 10 hours. <1> ~ <18> A manufacturing method described in any of the following. <20> The emulsification time in step 1 is between 0.1 hours and 8 hours. <1> ~ <19> A manufacturing method described in any of the following. <21> The emulsification time in step 1 is between 0.1 hours and 6.5 hours. <1> ~ <20> A manufacturing method described in any of the following. <22> The emulsification time in step 1 is between 0.1 hours and 6 hours. <1> ~ <21> A manufacturing method described in any of the following. <23> The liquid temperature of the oil mixture used for emulsification in step 1 is between 0°C and 50°C. <1> ~ <22> A manufacturing method described in any of the following. <24> The liquid temperature of the oil mixture used for emulsification in step 1 is between 0°C and 40°C. <1> ~ <23> A manufacturing method described in any of the following. <25> The liquid temperature of the oil mixture used for emulsification in step 1 is between 0°C and 35°C. <1> ~ <24> A manufacturing method described in any of the following. <26> The silica precursor comprises a tetraalkoxysilane. <1> ~ <25> A method for producing oil-containing silica capsule particles as described in any of the following. <27> The silica precursor is a tetraalkoxysilane having an alkoxy group with 1 to 4 carbon atoms. <1> ~ <26> A manufacturing method described in any of the following. <28> The silica precursor is one or more selected from tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane. <1> ~ <27> A manufacturing method described in any of the following. <29> In step 2, a pH adjuster is added to the emulsified liquid obtained in step 1 to adjust the pH of the emulsified liquid to 4.5 or less, and then oil-containing silica capsule particles are formed in a batch-type stirring tank. <1> ~ <28> A manufacturing method described in any of the following. <30> The pH of the emulsified liquid is 3.0 or higher and 4.5 or lower. <29> The manufacturing method described above. <31> The pH of the emulsified solution is 3.3 or higher and 4.3 or lower. <29> or <30> The manufacturing method described above. <32> In step 2, water is added to the emulsified liquid obtained in step 1 to dilute it, and then oil-containing silica capsule particles are formed in a batch-type stirring tank. <1> ~ <31> A manufacturing method described in any of the following. <33> The dilution in step 2 is carried out such that the total amount of oil and 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 above. <34> The mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing the surfactant and water in the oil mixture used in step 1 is 50 / 50 or more and 99 / 1 or less. <1> ~ <33> A manufacturing method described in any of the following. <35> The mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing the surfactant and water in the oil mixture used in step 1, and the oil phase component containing the oil and silica precursor, is 53 / 47 or more and 90 / 10 or less. <1> ~ <34> A manufacturing method described in any of the following. <36> The emulsification in step 1 is performed using the in-line emulsifying disperser in an external circulation manner. <1> ~ <35> A manufacturing method described in any of the following. <37> The emulsification in step 1 is performed by mixing a surfactant, water, oil, and silica precursor in-line to prepare the oil mixture, and then supplying the oil mixture to the in-line emulsifying disperser. <1> ~ <35> A manufacturing method described in any of the following. <38> The number of passes of the inline emulsifying and dispersing machine in step 1 is between 1 and 100,000. <36> or <37> The manufacturing method described above. <39> The number of passes of the inline emulsifying and dispersing machine in step 1 is between 1 and 10,000. <36> ~ <38> A manufacturing method described in any of the following. <40> The number of passes of the inline emulsifying and dispersing machine in step 1 is between 2 and 5,000. <36> ~ <39> A manufacturing method described in any of the following. <41> The number of passes of the inline emulsifying and dispersing machine in step 1 is between 3 and 3,000. <36> ~ <40> A manufacturing method described in any of the following. <42> Median diameter D of the emulsion droplets in the emulsion obtained in step 1 50 It is 10 μm or less. <1> ~ <41> A manufacturing method described in any of the following. <43> Median diameter D of the emulsion droplets in the emulsion obtained in step 1 50 The size is between 0.1 μm and 7 μm. <1> ~ <42> A manufacturing method described in any of the following. <44> Median diameter D of the emulsion droplets in the emulsion obtained in step 1 50 The size is between 0.3 μm and 5 μm. <1> ~ <43> A manufacturing method described in any of the following. <45> Median diameter D of the emulsion droplets in the emulsion obtained in step 1 50 The size is between 0.5 μm and 3 μm. <1> ~ <44> A manufacturing method described in any of the following. <46> In step 2, a disperser with a stirring blade is used. <1> ~ <45> A manufacturing method described in any of the following. <47> The aforementioned stirring blade is one or more selected from paddle blades, turbine blades, anchor blades, ribbon blades, and propellers. <46> The manufacturing method described above. <48> The stirring speed in step 2 is between 10 r / min and 200 r / min. <46> or <47> A manufacturing method described in any of the following. <49> The stirring speed in step 2 is 15 r / min or more and 100 r / min or less. <46> ~ <48> A manufacturing method described in any of the following. <50> The stirring speed in step 2 is between 20 r / min and 90 r / min. <46> ~ <49> A manufacturing method described in any of the following. [Examples]

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

[0067] [Median diameter D 50 ] Median diameter D of emulsion droplet 50 and median diameter D of oil-containing silica capsule particles 50The measurement was performed using a laser diffraction / scattering particle size distribution analyzer "LA-960" (product name, manufactured by Horiba, Ltd.). A flow cell was used for the measurement, the medium was water, and the refractive index of the dispersed phase was set to 1.45-0i. An aqueous dispersion containing an emulsified liquid or oil-containing silica capsule particles was added to the flow cell, and the measurement was performed at a concentration where the transmittance was approximately 90%, with the median diameter D measured by volume. 50 They sought it.

[0068] [Reaction rate of silica precursor] 100 mg of the oil mixture used for emulsification in step 1 was diluted with 10 g of methanol containing dodecane at a concentration of 10 μg / mL as an internal standard. This diluted solution was then measured using gas chromatography to determine the amount β of silica precursor in 100 mg of the oil mixture. Next, 100 mg of the emulsion obtained in step 1 was diluted with 10 g of methanol containing dodecane at a concentration of 10 μg / mL as an internal standard. This diluted solution was then measured using gas chromatography to determine the amount α of unreacted silica precursor 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 in 100 mg of emulsion α) / (Amount of silica precursor in 100 mg of oil mixture β)] × 100

[0069] <Model fragrance> Model fragrance A (volume-average cLogP: 3.7, specific gravity: 0.96), having the composition shown in Table 1, was used as the oil agent encapsulated in the silica capsule particles. The volume-average cLogP value of the model fragrance was calculated by multiplying the cLogP values ​​of the fragrance components contained in the model fragrance by their respective volume ratios within the model fragrance, and then summing these values.

[0070] [Table 1]

[0071] Example 1 (Process 1) In a 300L spherical-bottom cylindrical stirring tank (inner diameter 0.70m) equipped with 45° inclined paddle blades (blade diameter 0.35m), 0.7kg of Cotamine 60W (product name, manufactured by Kao Corporation; cetyltrimethylammonium chloride, active ingredient 30% by mass) and 89.4kg of deionized water were mixed at a temperature of 15°C and a stirring speed of 80 r / min for 10 minutes to prepare the aqueous phase component. To this aqueous phase component, an oil phase component was prepared by pre-mixing 47.9kg of model fragrance A as an oil agent and 12.0kg of tetraethoxysilane (hereinafter also referred to as "TEOS") as a silica precursor in a 200L drum, and added to obtain an oil agent mixture. The obtained oil mixture (150.0 kg) was emulsified at a temperature of 15°C by circulating and mixing it with the aforementioned paddle blades at a rotational speed of 80 r / min and an air-driven diaphragm pump at a flow rate of 40 L / min, while being circulated for 20 minutes using an in-line emulsifier / disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 40 m / s, in an external circulation system to obtain an emulsion. The median diameter D of the emulsion droplets of the obtained emulsion was... 50 The reaction rates of the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted by adding 89.4 kg of deionized water, and a 1% by mass aqueous sulfuric acid solution was added as a pH adjuster to adjust the pH to 3.7. Then, while raising and maintaining the liquid temperature at 30°C, the mixture was stirred at 80 r / min in the stirring tank using the paddle blades 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 emulsified liquid was 0.2 hours, which served as an indicator of emulsification productivity. A shorter time indicates better emulsification productivity.

[0072] Example 2 (Process 1) Internal volume of 6.5 m³ with 45° inclined paddle wings (wing diameter 1.3 m) 3In a spherical-bottom cylindrical stirring tank (inner diameter 1.9 m), 6.9 kg of Cortamine 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 the aqueous phase component. To this 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 in a tank with an internal volume of 6.5 m³. 3 An oil mixture was obtained by adding the oil phase components, which had been pre-mixed in a spherical-bottomed cylindrical tank. The obtained oil mixture (1475.0 kg) was emulsified at a temperature of 15°C by circulating and mixing it with the aforementioned paddle blades at a rotational speed of 35 r / min and an air-driven diaphragm pump at a flow rate of 50 L / min, while being circulated for 150 minutes using an in-line emulsifier / disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 40 m / s, in an external circulation system to obtain an emulsion. The median diameter D of the emulsion droplets of the obtained emulsion was... 50 The reaction rates of the silica precursor are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted by adding 879.1 kg of deionized water, and a 1% by mass aqueous sulfuric acid solution was added as a pH adjuster to adjust the pH to 3.7. Then, while raising and maintaining the liquid temperature at 30°C, the mixture was stirred at 35 r / min in the stirring tank using the paddle blades 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 emulsified liquid was 0.2 hours, which served as an indicator of emulsification productivity.

[0073] Example 3 (Process 1) A 15 m³ internal volume aircraft equipped with 45° inclined paddle wings (wing diameter 1.9 m). 3 In a spherical-bottom cylindrical stirring tank (inner diameter 2.5 m), 42.2 kg of Cortamine 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 the aqueous phase component. To this aqueous phase component, 2884.9 kg of Model Fragrance A as an oil and 722.7 kg of Tetraethoxysilane as a silica precursor were added to a tank with an internal volume of 15 m³. 3An oil mixture was obtained by adding the oil phase components, which had been pre-mixed in a spherical-bottomed cylindrical tank. The obtained oil mixture (9034.0 kg) was emulsified at a temperature of 15°C by circulating and mixing it with the aforementioned paddle blades at a rotational speed of 27 r / min and an air-driven diaphragm pump at a flow rate of 300 L / min, while being circulated for 140 minutes using an in-line emulsifier / disperser (product name "Cavitron CD1030", manufactured by Eurotech Co., Ltd.) with the outermost rotor peripheral speed set to 23 m / s, in an external circulation system to obtain an emulsion. The median diameter D of the emulsion droplets of the obtained emulsion was... 50 The reaction rates of the silica precursor and other factors are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted by adding 5384.3 kg of deionized water, and a 1% by mass aqueous sulfuric acid solution was added as a pH adjuster to adjust the pH to 3.7. Then, while raising and maintaining the liquid temperature at 30°C, the mixture was stirred at 27 r / min in the stirring tank using the paddle blades 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 emulsified liquid was 0.03 hours, which served as an indicator of emulsification productivity.

[0074] Example 4 (Process 1) In a 5L spherical-bottom cylindrical stirring tank equipped with 45° inclined paddle blades (blade diameter 0.35m), 9.3g of kotamine 60W and 1192.0g of deionized water were mixed at a temperature of 15°C and a stirring speed of 80 r / min for 10 minutes to prepare the aqueous phase component. To this aqueous phase component, an oil phase component was 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, and this was added to obtain an oil mixture. The obtained oil mixture (2 kg) was emulsified at a temperature of 15°C by circulating and mixing it with the aforementioned paddle blades at a rotational speed of 27 r / min and an air-driven diaphragm pump at a flow rate of 7 L / min, while being circulated and mixed using an in-line emulsifier / disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 5 m / s, for 3 hours and 59 minutes using an external circulation system. Subsequently, it was emulsified by circulating it for 1 minute at the outermost rotor speed of 23 m / s to obtain an emulsion. The median diameter D of the emulsion particles in the obtained emulsion was... 50 The reaction rates of the silica precursor and other factors are shown in Table 2. (Process 2) The emulsion obtained in step 1 was diluted by adding 1192.0 g of deionized water, and a 1% by mass aqueous sulfuric acid solution was added as a pH adjuster to adjust the pH to 3.7. Then, while raising and maintaining the liquid temperature at 30°C, the mixture was stirred at 27 r / min in the stirring tank using the paddle blades 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 by the same method as in Example 4, except that the mixture was circulated externally for 5 hours and 59 minutes using an inline emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 5 m / s, followed by circulation for 1 minute at the outermost rotor speed of 23 m / s.

[0076] Example 6 In the same manner as in Example 4, except that the oil mixture was emulsified at a liquid temperature of 30°C in Step 1 of Example 4, an aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained.

[0077] Example 7 An aqueous dispersion containing oil-containing silica capsule particles, as shown in Table 2, was obtained by the same method as in Example 5, except that in Step 1 of Example 5, the oil mixture was emulsified at a liquid temperature of 30°C.

[0078] Example 8 In step 1 of Example 5, an aqueous dispersion containing oil-containing silica capsule particles was obtained by the same method as in Example 5, except that the mixture was circulated externally for 9 hours and 59 minutes using an inline emulsifying and dispersing machine (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 5 m / s, followed by circulation for 1 minute at an outermost rotor 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 by the same method as in Example 7, except that the mixture was circulated externally for 6 hours and 59 minutes using an inline emulsifying disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 5 m / s, followed by circulation for 1 minute at an outermost rotor 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 with a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes. The resulting pre-emulsified liquid was then emulsified in a "one-pass method" by passing it only once through an in-line emulsifier / disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) at a rotor outer peripheral speed of 40 m / s. Except for these steps, an aqueous dispersion containing oil-containing silica capsule particles, as shown in Table 2, was obtained using the same method as in Example 4.

[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 with a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 80 r / min for 10 minutes. The resulting pre-emulsified liquid was then emulsified in a "one-pass method" by passing it only once through an in-line emulsifier / disperser (product name "Cavitron CD1010", manufactured by Eurotech Co., Ltd.) at a rotor peripheral speed of 40 m / s. Except for this, the aqueous dispersion containing oil-containing silica capsule particles shown in Table 2 was obtained using the same method as in Example 1.

[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 with a 45° inclined paddle blade (blade diameter 1.9 m) at a stirring speed of 27 r / min for 10 minutes. The resulting pre-emulsified liquid was then emulsified in a "one-pass method" by passing it only once through an in-line emulsifier / disperser (product name "Cavitron CD1030", manufactured by Eurotech Co., Ltd.) at a rotor peripheral speed of 40 m / s. Except for this, the method was the same as in Example 3 to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2.

[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 with a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes. Then, while maintaining the temperature and stirring speed of the pre-emulsified mixture, it was emulsified by circulating and mixing at a flow rate of 7 L / min using an air-driven diaphragm pump, and circulating for 1.5 minutes in an external circulation system using an inline emulsifier / disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 40 m / s. The rest of the process was the same as in Example 4 to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2.

[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 with a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes. Then, while maintaining the temperature and stirring speed of the pre-emulsified mixture, it was emulsified by circulating and mixing at a flow rate of 7 L / min using an air-driven diaphragm pump, and circulating it for 4 minutes in an external circulation system using an inline emulsifier / disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 40 m / s. The rest of the procedure was the same as in Example 4 to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2.

[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 with a 45° inclined paddle blade (blade diameter 0.35 m) at a stirring speed of 27 r / min for 10 minutes. Then, while maintaining the temperature and stirring speed of the pre-emulsified mixture, the mixture was circulated and mixed at a flow rate of 7 L / min using an air-driven diaphragm pump, and emulsified by circulating it externally for 12.5 minutes using an inline emulsifier / disperser (product name "Cavitron CD1000", manufactured by Eurotech Co., Ltd.) with the outermost rotor speed set to 40 m / s. The rest of the process was the same as in Example 4 to obtain an aqueous dispersion containing oil-containing silica capsule particles as shown in Table 2.

[0086] The encapsulation rate of the oil contained within the oil-containing silica capsule particles obtained in the examples was calculated and evaluated using the following method. The results are shown in Table 2. [Percentage of oil-based ingredients contained within] 100 mg of the aqueous dispersion containing 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. Then, ultrasonic waves were irradiated for 60 minutes using an ultrasonic irradiation device (Branson, model "5510") at an output of 180 W and an oscillation frequency of 42 kHz to dissolve the oil from the silica capsule particles and obtain a diluted solution. Subsequently, the amount of 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 oil-containing silica capsule particles was determined as the amount of oil blended. Separately, 100 mg of the aqueous dispersion containing oil-containing silica capsule particles obtained in step 2 was diluted with 10 g of deionized water, and then passed through a membrane filter (Millipore, product name "Omnipore", model number "JAWP04700") to recover the oil-containing silica capsule particles on the membrane filter. Furthermore, the silica capsule particles containing the oil were washed on a membrane filter with 10 mL of deionized water, followed by 10 mL of hexane. The silica capsule particles were then immersed in 2 mL of acetonitrile containing dodecane at a concentration of 10 μg / mL as an internal standard. Ultrasound was then irradiated for 60 minutes using an ultrasonic device (Branson, model "5510") at an output of 180 W and an oscillation frequency of 42 kHz to dissolve the oil from within the silica capsule particles. This solution was then passed through a membrane filter again (Toyo Roshi Co., Ltd., product name "DISMIC", model "13JP020AN"). The amount of methyl dihydrojasmonate contained in this solution was measured using gas chromatography, and this amount was defined as x, the amount of methyl dihydrojasmonate encapsulated in the silica capsule particles. The encapsulation rate of the oil was calculated using the following formula. Encapsulation rate of oil (%) = {(Amount of methyl dihydrojasmonate encapsulated in the 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] Table 2 shows that the method described in the example has a high oil content. Furthermore, Examples 1-3, 11, and 12 demonstrate excellent emulsification productivity, as evidenced by the short time required to produce 100 kg of emulsified liquid despite the use of a large amount of oil mixture in step 1. [Industrial applicability]

[0089] According to the present invention, it is possible to produce oil-containing silica capsule particles with a high oil encapsulation rate. 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 large quantities of oil mixtures.

Claims

1. A method for producing oil-containing silica capsule particles having an oil-containing core and a shell composed of silica, Step 1: A step in which an oil mixture containing a surfactant, water, an oil agent, and a silica precursor is emulsified using an in-line emulsifying and dispersing machine to obtain an emulsion, The amount of oil mixture used in step 1 is 100 kg or more. A step in which the reaction rate of the silica precursor in the resulting emulsion is 60% or less, and A method for producing oil-containing silica capsule particles, comprising: Step 2: Using the emulsified liquid obtained in Step 1, forming oil-containing silica capsule particles in a batch-type stirring tank.

2. A method for producing oil-containing silica capsule particles according to claim 1, wherein the reaction rate of the silica precursor in the emulsified liquid obtained in step 1 is 55% or less.

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

4. In the emulsification process of step 1, the rotational energy Q'' of the rotor per unit volume of the emulsification and dispersion chamber and the amount of oil dispersion in the in-line emulsification and dispersion machine is 1 × 10⁻⁶ 4 W・h / (m) 3 A method for producing oil-containing silica capsule particles according to claim 3, wherein the amount is 1 kg or more.

5. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the amount of oil-containing mixed liquid used in step 1 is 300 kg or more.

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

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

9. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein in step 2, water is added to the emulsified liquid obtained in step 1 to dilute it, and then oil-containing silica capsule particles are formed in a batch-type stirring tank.

10. A method for producing oil-containing silica capsule particles according to claim 9, wherein the dilution in step 2 is performed such that the total amount of oil and 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.

11. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the mass ratio (aqueous phase component / oil phase component) of the aqueous phase component containing a surfactant and water in the oil mixture used in step 1 is 50 / 50 or more and 99 / 1 or less.

12. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the emulsification in step 1 is performed using the in-line emulsifying disperser in an external circulation manner.

13. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein the emulsification in step 1 is performed by mixing a surfactant, water, an oil, and a silica precursor in-line to prepare the oil mixture, and then supplying the oil mixture to the in-line emulsification disperser.

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

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

16. A method for producing oil-containing silica capsule particles according to claim 1 or 2, wherein in step 2, a disperser using a stirring blade is used.

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