Methods for manufacturing microcapsules

Abstract

The present invention addresses situations where it is difficult to manufacture microcapsules using interfacial polymerization even when a solution containing a film-forming substance is used. It provides a more efficient and reliable manufacturing method that can easily produce microcapsules. That is, a method for manufacturing microcapsules is provided, characterized in that it uses two latex particles of different sizes to manufacture microcapsules. The method consists of the following steps: a latex forming step, forming two kinds of latex (1) and (2) that are common to continuous phases, such that one of the two monomers that react with each other to form a film is contained in the latex particles (1) of latex (1), and the monomer of the other is contained in the latex particles (2) of latex (2); a microcapsule forming step, mixing latex (1) and latex (2) to polymerize their interface, wherein the average particle size (R) of the latex particles (1) of latex (1) is 0.1~300 μm, the average particle size (r) of the latex particles (2) of latex (2) is 0.01~30 μm, and r / R≦0.1.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing microcapsules, which uses two types of latex particles of different sizes. [Previous Technology]

[0002] Microcapsules with a shell encapsulating a core agent have been used in a wide variety of fields. For example, water-containing microcapsules, which use water as the core material, are used as a medium for storing heat and cold in heat exchangers, etc., utilizing the latent heat of water. Thermally expandable microcapsules, which use hydrocarbons as the core material, are used in a wide range of applications as design additives and lightweighting agents. They are also used in coatings and other materials for the purpose of lightweighting, and are incorporated into materials such as wallpaper. On the other hand, in epoxy resin compositions used in adhesives, sealants, coatings, etc., microcapsules with a shell encapsulating the hardener or hardening accelerator used to cure the epoxy resin are used to make the epoxy resin and the hardener or hardening accelerator used to cure the epoxy resin a stable single liquid, thus giving it latent properties.

[0003] However, compared to cases where the core is hydrophobic, the development of microcapsules with a core primarily composed of water-soluble substances, or methods for manufacturing them, has been relatively slow. Furthermore, in cases where the core is hydrophobic, there are also issues where microcapsules that can reliably retain their contents by reacting with the aqueous phase are not obtained.

[0004] As a known method for manufacturing microcapsules with a water-soluble core, as disclosed in Japanese Patent Application Publication No. 2-258052 (Patent Document 1), hexane, an organic solvent, is used in the core to form an O / W emulsion. Subsequently, an aqueous solution containing hexanediamine for forming a film is added, and the mixture is heated to evaporate the hexane, thereby forming a film on the particle surface and obtaining microcapsules with a high water content. This method addresses the issue that if a water-soluble substance is used in the core from the beginning, the storage stability cannot be maintained, but the step of evaporating the organic solvent is required, making the manufacturing process unsafe and complex.

[0005] In contrast, Japanese Patent Application Publication No. 2012-140600 (Patent Document 2) describes a process in which a water-soluble substance containing a water-soluble free radical polymerization initiator is used as the core agent. After the core is formed by free radical polymerization, an interfacial polymerization is further performed on the surface of the core to form a film, thereby obtaining microcapsules. However, according to this manufacturing process, obtaining the desired microcapsules requires a two-stage reaction, which cannot be considered a simple manufacturing step.

[0006] Furthermore, Japanese Patent Publication No. 6-018636 (Patent Document 3) discloses a method for preparing microcapsules by mixing a first O / W type aqueous organic latex and a second O / W type aqueous organic latex. The first O / W type aqueous organic latex uses a solution containing a first oil-soluble reactive substance, namely polyisocyanate, as the oil phase and a solution containing a surfactant as the aqueous phase. The second O / W type aqueous organic latex uses a solution containing a second oil-soluble reactive substance, namely amine, as the oil phase and a solution containing a surfactant as the aqueous phase. However, with this method, there are concerns about side reactions other than film formation due to the reaction between water and isocyanate in the production of the polyisocyanate and aqueous latex. Furthermore, it is unclear how the reactants are exchanged through the collision of droplets. Also, the reaction time is 4 to 24 hours, and a simpler method for manufacturing high-quality microcapsules is being sought.

[0007] It is desirable to efficiently obtain strong, dense microcapsules that can encapsulate various beneficial substances and suppress leakage. Furthermore, it is also desirable to obtain strong microcapsules that can encapsulate epoxy resin hardeners and exhibit excellent storage stability.

[0008] [Prior Art Documents] [Patent Document 1] Japanese Patent Application Publication No. Hei 2-258052 [Patent Document 2] Japanese Patent Application Publication No. 2012-140600 [Patent Document 3] Japanese Patent Application Publication No. 6-018636 [Summary of the Invention]

[0009] [Summary of the Invention] [Problem to be Solved by the Invention] The object of the present invention is to provide microcapsules easily by means of a more efficient and reliable interfacial polymerization method, even when it is difficult to manufacture microcapsules by means of interfacial polymerization method when a solution containing a film-forming substance is used.

[0010] [Means for solving the problem] The present invention provides the following: [1] A method for manufacturing microcapsules, characterized in that it uses two latex particles of different sizes to manufacture microcapsules. The method comprises the following steps: a latex forming step, forming two latexes (1) and (2) that are common to continuous phases respectively, such that one of the two monomers that react with each other to form a film is contained in the latex particles (1) of latex (1), and the monomer of the other is contained in the latex particles (2) of latex (2); a microcapsule forming step, mixing latex (1) and latex (2) to polymerize their interface, wherein the average particle size (R) of the latex particles (1) of latex (1) is 0.1~300 μm, the average particle size (r) of the latex particles (2) of latex (2) is 0.01~30 μm, and r / R≦0.1. [2] In the method for manufacturing microcapsules as described in [1], the average particle size (R) of the latex particles (1) is 0.1 to 100 μm, the average particle size (r) of the latex particles (2) is 0.01 to 10 μm, and r / R ≦ 0.1. [3] In the method for manufacturing microcapsules as described in [1] or [2], after the latex forming step, the average particle size (R) of the latex particles (1) or the average particle size (r) of the latex particles (2) is adjusted to a predetermined range. [4] In the method for manufacturing microcapsules as described in any of [1] to [3], the increase rate of the average particle size (R) in the microcapsule forming step is less than 1.3 times. [5] In the method for manufacturing microcapsules as described in any of [1] to [4], the continuous phase is flowing paraffin or silicone oil. [6] In any of the methods for manufacturing microcapsules described in [1] to [5], one of the two monomers that react with each other to form a membrane is an isocyanate compound having two or more isocyanate groups in one molecule, and the other monomer is selected from the group consisting of: polyamine compounds having two or more amine groups in one molecule, polyhydroxy compounds having two or more hydroxyl groups in one molecule, and combinations thereof. [7] In any of the methods for manufacturing microcapsules described in [1] to [6], the core agent of the microcapsule is water, a water-soluble heat storage material, a thermally expandable hydrocarbon or its fluoride, an epoxy resin curing agent, or an epoxy resin curing accelerator. [8] In any of the methods for manufacturing microcapsules described in [1] to [7], the aforementioned epoxy resin curing agent includes polyisocyanate, bisphenol A type epoxy resin, and imidazole compound. [9] The method for manufacturing microcapsules as described in any of [1] to [8], wherein the epoxy resin curing agent is a liquid mixture of premixed polyisocyanate, bisphenol A type epoxy resin and imidazole compound, which is then heated and stirred.

[10] The method for manufacturing microcapsules as described in any of [1] to [9], wherein the reaction time of the microcapsule formation step is within 6 hours.

[0011] [Effects of the Invention] According to the present invention, even when it is difficult to manufacture stable microcapsules using interfacial polymerization methods that involve adding solutions of substances having film-forming materials and polymerization reaction materials, the interfacial polymerization method using latex of the present invention can efficiently and easily obtain microcapsules of any particle size. Furthermore, a capsule can be provided that maintains a high water content when encapsulating an aqueous substance in the core material, and exhibits excellent pressure resistance when encapsulating a hydrophobic substance in the core material.

Implementation Method

[0012] [Forms for implementing the invention] <Definitions> In this specification, the term "common continuous phase" means that the continuous phases forming the latex are the same or can be dissolved in each other. It includes the following concepts: the use of completely identical continuous phases, and the use of continuous phases that are different in composition but can be dissolved in each other.

[0013] The present invention provides a method for manufacturing microcapsules, characterized in that it uses two types of latex particles of different sizes to manufacture microcapsules. The method comprises the following steps: a latex forming step, forming two types of latex (1) and (2) that are continuous phases, such that one of the two monomers that react with each other to form a film is contained in the latex particles (1) of latex (1), and the monomer of the other is contained in the latex particles (2) of latex (2); a microcapsule forming step, mixing latex (1) and latex (2) to polymerize their interface, wherein the average particle size (R) of the latex particles (1) of latex (1) is 0.1~300 μm, the average particle size (r) of the latex particles (2) of latex (2) is 0.01~30 μm, and r / R≦0.1. The present invention uses two types of latex particles of different sizes to manufacture microcapsules. The following is necessary: ​​the two latex systems are formed separately and independently, the average particle size (R) of the latex particles (dispersed phase) (1) of latex (1) is 0.1~300 μm, the average particle size (r) of the latex particles (dispersed phase) (2) of latex (2) is 0.01~20 μm, and r / R≦0.1. That is, it is necessary that the average particle size (R) of the latex particles (1) of latex (1) is larger, and the average particle size (r) of the latex particles (2) of latex (2) is smaller by 1 / 10. Moreover, in the microcapsule formation step, the two latexes are mixed and polymerized at the same interface, that is, the polymerization reaction is carried out to form capsules. It is believed that the smaller latex particles (2) are attached to the periphery of the larger latex particles (1), and a polymerization reaction is induced at the interface to form a film and construct microcapsules.

[0014] Since the latex (1) contains a core of microcapsules, the core is water when it encapsulates water. When microcapsules are formed for use as heat storage materials, a water-soluble heat storage material that stores or releases heat through a phase change is used. Specifically, the water-soluble heat storage material uses one or more of the following groups: sugars, sugar alcohols, inorganic salts, and inorganic salt hydrates.

[0015] As an additive used to effectively emulsify the aforementioned core agent, when the core agent is aqueous, suitable choices include: a gelling agent that dissolves in an aqueous solvent and gels, and a dispersing stabilizer used to stabilize the core agent. Examples of gelling agents include: polyvinyl alcohol, polyvinylphenol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, polymethacrylic acid, polyethylene glycol, methylcellulose, hydroxypropylcellulose, agar, gelatin, sodium alginate, etc. These can be used alone or in combination of two or more. Examples of dispersing stabilizers include: silicon dioxide, calcium phosphate, magnesium hydroxide, aluminum hydroxide, ferric hydroxide (III), barium sulfate, calcium sulfate, sodium sulfate, calcium oxalate, calcium carbonate, barium carbonate, magnesium carbonate, etc.

[0016] Furthermore, in the case of generating microcapsules used as thermal expansion agents, the core agent is: a straight-chain aliphatic hydrocarbon with 3 to 8 carbon atoms, a branched aliphatic hydrocarbon with 3 to 8 carbon atoms, a cyclic aliphatic hydrocarbon with 3 to 8 carbon atoms, an ether compound having a hydrocarbon group with 2 to 8 carbon atoms, or a fluoride in which one of the hydrogen atoms of the hydrocarbon group has been replaced by a fluorine atom. More specifically, examples include: propane, cyclopropane, butane, cyclobutane, isobutane, pentane, cyclopentane, neopentane, isopentane, hexane, cyclohexane, 2-methylpentane, 2,2-dimethylbutane, heptane, cycloheptane, octane, cyclooctane, methylheptane derivatives, trimethylpentane derivatives, C3F7OCH3, C4F9OCH3, C4F9OC2H5, and other hydrofluoroethers. One or a mixture of one or more of these can be used. Furthermore, the following can also be selected as expanding agents: dialkyl peroxides, diacetyl peroxide, peroxy esters, dicarbonate peroxides, and azo compounds that are peroxides.

[0017] As the core agent of the microcapsules of the present invention, a curing agent or curing accelerator for curing epoxy resin may also be used. Specifically, examples of curing agents or curing accelerators for the aforementioned epoxy resin include imidazole compounds and amine compounds. Examples of imidazole compounds include: 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-dodecyl-2-methyl-3-benzylimidazole chloride, 2-undecylimidazole, 2-heptadecylimidazole, 1-cyanoethylimidazole, etc. Examples of amine compounds include: ethylenediamine, butanediamine, hexamethylenediamine, octanediamine, diethylenetriamine, triethylenediamine, triethylenetriamine, dimalonide, 1,3-bis(hydrazylcarbonylethyl)-5-isopropylhydantoin, 1,8-diazabicyclo[5.4.0]undecyl-7-ene, 2,4,6-tris(dimethylamino)phenol, 2-dimethylaminophenol, etc. These imidazole compounds and amine compounds can be used alone or in combination of two or more.

[0018] Furthermore, the aforementioned imidazole compounds or amine compounds can also be used as imidazole adducts or amine adducts of epoxy resins. Examples of adducts include compounds obtained by reacting epoxy resin with an imidazole compound or with an amine compound; these are preferably imidazole adducts of epoxy resins composed of an imidazole compound and an epoxy resin. There are no particular restrictions on the solvents used in the manufacture of imidazole adducts, such as hydrocarbons like benzene, toluene, xylene, cyclohexane, mineral oil, and naphtha; ketones like acetone, methyl ethyl ketone, and methyl isobutyl ketone; and esters like ethyl acetate, n-butyl acetate, and propylene glycol monomethyl ether acetate. Using these solvents is also acceptable. The amount of epoxy resin added relative to the imidazole compound should preferably be in the range of 1:0.2 to 1:5 relative to the active hydrogen equivalent (amine value) of the imidazole compound. If the equivalence ratio is less than 1:0.2, meaning the amount of epoxy resin added is small, the flowability of the imidazole compound increases, making it unsuitable for long-term storage stability. On the other hand, if the equivalence ratio is greater than 1:5, meaning the amount of epoxy resin added increases, the viscosity increases, making it difficult to form small droplets in the subsequent emulsification step, thus making it difficult to obtain microcapsules with small particle sizes. Therefore, the amount of epoxy resin added relative to the imidazole compound should preferably be 1:0.3 to 1:1 relative to the active hydrogen equivalent (amine value) of the imidazole compound.

[0019] The shell (membrane) of the microcapsule manufactured in this invention is formed by two monomers that react with each other to form a membrane. An example of this invention is preferably a polyisocyanate reacting with a polyhydroxy compound (forming a polyurethane membrane) or a polyamine compound (forming a polyamide membrane) to form a membrane.

[0020] Polyisocyanates include aliphatic polyisocyanates and aromatic polyisocyanates. Examples of aliphatic polyisocyanates include: trimethyl diisocyanate, hexamethyl diisocyanate, propyl-1,2-diisocyanate, butyl-1,2-diisocyanate, cyclohexyl-1,2-diisocyanate, cyclohexyl-1,3-diisocyanate, cyclohexyl-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis(isocyanate methyl)cyclohexane and 1,3-bis(isocyanate methyl)cyclohexane, isoflavone diisocyanate, lysine diisocyanate, hydrogenated methyl diisocyanate, etc. Examples of aromatic polyisocyanates include: m-phenyl diisocyanate, p-phenyl diisocyanate, 2,6-methylene phenyl diisocyanate, 2,4-methylene phenyl diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, styrannosyl-1,4-diisocyanate, styrannosyl-1,3-diisocyanate, 4-chlorostyrannosyl-1,3-diisocyanate, 2-methylstyrannosyl-1,3-diisocyanate, 4,4'-diphenylpropane diisocyanate, and 2,2-bis(4-isocyanoxyphenyl)hexafluoropropane. While the above examples illustrate difunctional diisocyanate compounds, the examples can also be extrapolated to include trifunctional triisocyanate compounds and tetrafunctional tetraisocyanate compounds.

[0021] Examples of condensates, polymers, or adducts of isocyanate compounds include: trimers of the above-mentioned difunctional isocyanate compounds, namely biuret compounds or trimer isocyanates; multifunctional compounds formed as adducts of polyols such as trimethylolpropane and difunctional isocyanate compounds; formalin condensates of benzene isocyanates; polymers of isocyanate compounds having polymerizable groups, such as methacryloyloxyethyl isocyanate; and lysine triisocyanate.

[0022] Polyisocyanate compounds are described in the "Handbook of Polyurethane Resins" (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun Co., Ltd. (1987)).

[0023] In the above, the shell of the microcapsule is preferably a polymer containing a trifunctional or higher isocyanate. Examples of trifunctional or higher isocyanates include: aromatic isocyanate compounds with trifunctional or higher functions, aliphatic isocyanate compounds with trifunctional or higher functions, etc. Examples of trifunctional or higher isocyanate compounds are preferably adducts of difunctional isocyanate compounds (compounds having two isocyanate groups in the molecule) and compounds having three or more active hydrogen groups in the molecule (trifunctional or higher, such as polyols, polyamines, or polythiols, etc.) to form trifunctional or higher isocyanate compounds (adduct type); it is also preferable to be a trimer of difunctional isocyanate compounds (biuret type or trimer isocyanate type). Specific examples of isocyanate compounds with three or more functions include: 2,6-methylenephenyl diisocyanate, 2,4-methylenephenyl diisocyanate or hexamethylene diisocyanate, their adducts with trimethylolpropane, biuret, trimerocyanate, etc.

[0024] Isocyanate compounds with adduct type, having three or more functions, may also use commercially available products. Examples of commercially available products include: Takenate (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D-140N, D-160N (all manufactured by Mitsui Chemicals, Inc.); Desmodur (registered trademark) L75, UL57SP (manufactured by Sumitomo Chemical Bayerurethane, Inc.); Coronate (registered trademark) HL, HX, L (manufactured by Nippon Polyurethane, Inc.); P301-75E (manufactured by Asahi Kasei, Inc.); Burnock (registered trademark) D-750 (manufactured by DIC, Inc.), etc. Triisocyanate-type isocyanate compounds with three or more functions can use commercially available products, such as: Takenate (registered trademark) D-127N, D-131N, D-132N, D-170N, D-170HN, D-172N, D-177N, D-204, D-262; STABIO (registered trademark) D-370N (manufactured by Mitsui Chemicals, Inc.); Sumijour N3300, Desmodur (registered trademark) N3600, N3900, Z4470BA (Sumitomo Chemical Bayerurethane); Coronate (registered trademark) HX, HK (manufactured by Nippon Polyurethane Co., Ltd.); Duranat (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, TSE-100 (manufactured by Asahi Kasei Corporation), etc. Biuret-type isocyanate compounds with three or more functionalities can use commercially available products, such as: Takenate (registered trademark) D-165N, NP1100 (manufactured by Mitsui Chemicals Co., Ltd.), Desmodur (registered trademark) N3200 (Sumitomo Chemical Bayerurethane), Duranat (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation), etc.

[0025] The polyisocyanate in this invention can be used alone or in combination with two or more types.

[0026] The aforementioned polyhydroxy compound is preferably free of isocyanate groups or amino groups, more preferably free of both isocyanate groups and amino groups. There is no particular limitation on the number of hydroxyl groups in one molecule of the aforementioned hydroxy compound, but it is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 or 3.

[0027] Examples of the aforementioned polyhydroxy compounds include organic polyhydroxy compounds, such as ethylene glycol, propylene glycol, and alkyl diols like 1,4-butanediol. When polycondensation is used to form polyurethane, the aforementioned hydroxy compounds may be only one type or two or more types. In the case of two or more types, their combination and ratio can be arbitrarily chosen.

[0028] Furthermore, a catalyst may be added to promote the reaction during the formation of polyurethane. For example, one or more of the following catalysts may be used: 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]-5-nonene (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), etc.

[0029] Polyamine compounds include substances containing two or more amino groups. Examples include: ethylenediamine, propylenediamine, 1,4-butanediamine, 1,5-pentanediamine, hexanediamine, 1,8-octanediamine, bis(2-aminoethyl)amine, tri(2-aminoethyl)amine, tri(3-aminopropyl)amine, bis(hexamethylene)triamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N,N'-bis(2-aminoethyl)-1,3-propanediamine, N,N'-bis(3-aminopropyl)ethylenediamine, 1,2-bis(2-aminoethoxy)ethane, 1,4-butanediol bis(3-aminopropyl) ether, diethylene glycol bis(3-aminopropyl) ether, etc. Preferably, the polyamine compound is selected from at least one of tris(2-aminoethyl)amine, bis(2-aminoethyl)amine, bis(hexamethylene)triamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexamethylenediamine. The polyamine compound can be used alone or in combination of two or more.

[0030] When the continuous phase of the latex of the present invention is an aqueous phase, it can be composed of an aqueous medium and an emulsifier. The aqueous medium is preferably water. The total mass of the aqueous medium relative to the mixture of the oil phase and the aqueous phase, i.e., the latex, is preferably 20% to 80% by mass, more preferably 30% to 70% by mass, and even more preferably 40% to 60% by mass.

[0031] The above-mentioned emulsifiers contain dispersants or surfactants or combinations thereof. Examples of dispersants include: polyvinyl alcohol and its modified forms (e.g., anionic modified polyvinyl alcohol), polyacrylamide and its derivatives, ethylene-vinyl acetate copolymers, styrene-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, polyvinylpyrrolidone, ethylene-acrylic acid copolymers, vinyl acetate-acrylic acid copolymers, carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch derivatives, gum arabic, and sodium alginate, etc.

[0032] Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Surfactants can be used alone or in combination of two or more.

[0033] There are no particular limitations on nonionic surfactants; those previously known may be used. Examples include: polyoxyethylene ethyl alkyl ether compounds, polyoxyethylene ethyl alkyl phenyl ether compounds, polyoxyethylene ethyl polystyrene phenyl ether compounds, polyoxyethylene ethyl polyoxyethylene propyl alkyl ether compounds, glycerol fatty acid partial ester compounds, dehydrated sorbitol fatty acid partial ester compounds, neopentyl tertrol fatty acid partial ester compounds, propylene glycol monofatty acid ester compounds, sucrose fatty acid partial ester compounds, polyoxyethylene ethyl dehydrated sorbitol fatty acid partial ester compounds, polyoxyethylene ethyl sorbitol fatty acid partial ester compounds, polyethylene glycol fatty acid ester compounds, polypropylene glycol fatty acid partial ester compounds, polyoxyethylene ethylated castor oil compounds, polyoxyethylene ethyl glycerol fatty acid partial ester compounds, fatty acid diethanolamine compounds, N,N-bis(2-hydroxyethyl)alkylamine compounds, polyoxyethylene ethyl alkylamine, triethanolamine fatty acid esters, trialkylamine oxides, polyethylene glycol, and copolymers of polyethylene glycol and polypropylene glycol.

[0034] There are no particular limitations on anionic surfactants; those already known may be used. Examples include: fatty acid salts, rosinates, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfonate succinates, linear alkylbenzene sulfonates, branched alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenyloxypolyoxyethylene ethylpropyl sulfonate, polyoxyethylene ethylalkyl sulfonate phenyl ether salts, N-methyl-N-oleyl taurate sodium salt, N-alkyl sulfonate succinate monoacrylamide disodium salt, petroleum sulfonates, sulfated tallow, sulfated salts of fatty acid alkyl esters, alkyl sulfates, and polyoxyethylene sulfonate. Alkyl ether sulfate salts, fatty acid monoglyceride sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, polyoxyethylene styrene phenyl ether sulfate salts, alkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, polyoxyethylene alkyl phenyl ether phosphate salts, partially saponified styrene-maleic anhydride copolymers, partially saponified olefin-maleic anhydride copolymers, naphthalene sulfonate formaldehyde condensate, alkyl polyoxyethylene alkyl sulfonate alkyl ether salts, alkenyl polyoxyethylene alkyl sulfonate alkyl ether salts, etc.

[0035] There are no particular limitations on cationic surfactants, and those previously known may be used. Examples include: alkylamine salts, quaternary ammonium salts (e.g., hexadecyltrimethylammonium chloride), polyoxyethylene ethyl alkylamine salts, and polyethylene-polyamine derivatives.

[0036] There are no particular limitations on the amphoteric surfactants; those already known may be used. Examples include: carboxybetaine, aminocarboxylic acid, sulfonated betaine, amino sulfate, and imidazoline.

[0037] The concentration of the emulsifier relative to the total mass of the mixture of the oil phase and the water phase, i.e., the latex, is preferably greater than 0% by mass and less than 20% by mass, more preferably greater than 0.005% by mass and less than 15% by mass, more preferably greater than 0.01% by mass and less than 12% by mass, and most preferably greater than 1% by mass and less than 10% by mass.

[0038] The aqueous phase may also contain other components such as ultraviolet absorbers, antioxidants, and preservatives, depending on the requirements.

[0039] In the case where the continuous phase of the present invention is an oil phase, it may further contain solvents and / or additives.

[0040] Examples of solvents include: fatty acid ester compounds such as tri(octanoic acid / decanoic acid) glycerol ester and isopropyl tetradecanoate; alkyl naphthalene compounds such as diisopropylnaphthalene; diaryl alkane compounds such as 1-phenyl-1-dimethylethane; alkyl biphenyl compounds such as isopropyl biphenyl; aromatic hydrocarbons such as triarylmethane compounds, alkylbenzene compounds, benzyl naphthalene compounds, diaryl olefin compounds, and aryl indane compounds; aliphatic hydrocarbons such as dibutyl phthalate, paraffin wax, and isoalkanes; natural animal and vegetable oils such as silicone oil, tea seed oil, soybean oil, corn oil, cottonseed oil, rapeseed oil, olive oil, coconut oil, castor oil, and fish oil; and high-boiling fractions of natural substances such as mineral oil.

[0041] The solvent may contain the above-mentioned surfactants. Furthermore, additives such as ultraviolet absorbers, photostabilizers, antioxidants, waxes, and odor suppressants may be encapsulated in microcapsules as needed.

[0042] The additive may contain 0% to 20% by mass relative to the total mass of the core material, preferably 1% to 15% by mass, and more preferably 5% to 10% by mass.

[0043] <Latex Formation Step> Latex formation refers to dispersing a liquid phase (dispersed phase) that is insoluble in the solvent of the continuous phase of the present invention in the form of latex particles in the continuous phase of the present invention. Emulsification can be carried out using means commonly used for the dispersion of the dispersed phase and the continuous phase, such as general-purpose mixers, homogenizers, Manton Gaulin, ultrasonic dispersers, dissolvers, Keddy mills or other known dispersion devices. Latex (1) is formed by dispersing the material that will become the dispersed phase of latex particles (1) in the continuous phase to form latex (1). Furthermore, the above-described latex formation step can also be applied to the latex (2) of the present invention, which contains a compound (film-forming substance) that can polymerize at the interface with the latex particles (1) in the latex (1).

[0044] The latex (2) of the present invention can be latexed in a continuous phase by using film-forming monomers that react with each other to form a film as the dispersed phase (latex particles (2)); or by using an auxiliary solvent that is insoluble in the continuous phase solvent but can dissolve the film-forming monomers as the dispersed phase for latexing. Examples of auxiliary solvents include ketone compounds such as methyl ethyl ketone, ester compounds such as ethyl acetate, and alcohol compounds such as isopropanol.

[0045] The latex particles (2) in the above-mentioned latex (2) should preferably have a solubility of 5% by weight or more in the latex particles (1) of the latex (1). Solubility refers to the solubility of latex particles (2) in the latex particles (1). If the solubility is high, it will be easier to form a film (shell of microcapsules) during the subsequent polymerization reaction (interfacial polymerization reaction). If the solubility is 12% by weight or more, it is preferably 10% by weight or more, more preferably 5% by weight or more, with an upper limit of 88% by weight, preferably 90% by weight, and more preferably 95% by weight.

[0046] As a specific example, in the case where ethylenediamine is used as the dispersed phase, polyvinylpyrrolidone is used as a dispersing stabilizer, and it is dispersed in a continuous phase composed of a paraffinic solvent at a predetermined stirring speed to form a latex. This becomes latex (1). On the other hand, latex (2) is formed by dispersing polyisocyanate with the same paraffinic solvent at a predetermined stirring speed. The particle size of the dispersed phase can be controlled by changing the stirring speed or by changing the stirring blades used. In another example, polyisocyanate is used as the dispersed phase, and imidazole, a hydrophobic substance, is incorporated and dispersed in a paraffinic solvent at a predetermined stirring speed to form latex (1). On the other hand, latex (2) is formed by dispersing hexamethylenediamine as the dispersed phase and a paraffinic solvent as the continuous phase at a predetermined stirring speed. For example, when using an adduct of bisphenol A type epoxy resin (an epoxy resin curing agent or curing accelerator) as the core of latex particles (1) of latex (1), firstly, imidazole and methyl ethyl ketone are mixed in bisphenol A type epoxy resin to form an adduct. By dispersing it in a paraffin-based solvent at a predetermined stirring speed, it can be used as latex (1). If this is used instead of the imidazole in the latex (1) using polyisocyanate and imidazole as described above, and combined with a latex (2) formed from hexamethylenediamine, microcapsules can be formed in the core of microcapsules containing epoxy resin curing agents or curing accelerators.

[0047] <Microcapsule Formation Step> The microcapsule formation step is: mixing the latex (1) and (2) formed above, and carrying out a polymerization reaction (interfacial polymerization reaction) to form the shell (membrane) of the microcapsule. The polymerization reaction is a step in which latex particles (1) in latex (1) collide with latex particles (2) containing membrane-forming substances contained in latex (2), and polymerize at their interface, thereby forming the shell (membrane) of the microcapsule. The polymerization reaction is preferably carried out under heating. The temperature of the polymerization reaction is usually 40°C to 100°C, preferably 50°C to 80°C. Although the higher the polymerization temperature, the shorter the polymerization time, there is a risk that the reaction will be faster and coagulation will easily occur. In this case, it is desirable to start the reaction at a relatively low temperature and then raise the temperature.

[0048] According to the inventors' review, it is understood that if the solubility of latex particles (2) in latex particles (1) is 5% by weight or more, then when manufacturing microcapsules, the latex particles (2) contained in latex (2) collide with the latex particles (1) contained in latex (1) and merge together, thereby increasing the tendency to promote the formation of the shell (membrane). There are no particular limitations on combinations with a solubility of 5% by weight or more. For example, when the core agent is a water-soluble substance, when using an auxiliary solvent in latex (2), diethyl ether with a solubility of 6.9% in water, ethyl acetate with a solubility of 8.3%, methyl ethyl ketone with a solubility of 27.5%, acetone, and tetrahydrofuran can be used. When the latex particles (1) are imidazole compounds, ethylenediamine, hexamethylenediamine, or other amines with high solubility for imidazole can be used alone in latex (2).

[0049] In order to stabilize and maintain the performance of the capsule of the present invention, the size of the capsule should be uniform. Therefore, before and after the addition of the latex (2) of the present invention, the average particle size of the latex particles (1) of the latex (1) should be uniform, and the average particle size distribution should be less than 1.3 times the average particle size.

[0050] As a means to make the average particle size of the microcapsules of the present invention uniform, latex (2) can be added after the latex (1) is emulsified and the size of the latex particles (1) of the latex (1) grows to the desired size. The above-mentioned growth of the average particle size of the latex particles to the desired size means that the droplet diameter increases as the latex particles (1) of the latex (1) are combined with each other. The desired size of the latex particles (1) can be obtained by adjusting the shear force and shear time along with the change of viscosity of the continuous phase and stirring speed.

[0051] The inventors have discovered that after latex (1) is formed, by maintaining a certain stirring speed, even if the average droplet diameter increases, the dispersion value (standard deviation) in the average particle size distribution of the latex particles (1) will not increase to a certain extent. As a result, it can be seen that when the latex particles composed of latex (2) and latex (1) are combined, their particle size will be less than 1.3 times. That is, the increase rate of the average particle size (R) in the microcapsule formation step is less than 1.3 times.

[0052] The appropriate time to add latex (2) is when the average particle size dispersion value of latex particles caused by stirring latex (1) increases to the limit and then the latex (2) begins to merge together. The difference in particle size before and after the addition will be smaller, so it is appropriate.

[0053] The average particle size (R) of the latex particles (1) composed of latex (1) in this invention is preferably 0.1 to 300 μm. If the average particle size of the latex particles (1) is less than 0.1 μm, the latex particles (1) may aggregate and hinder the reaction. If the average particle size of the latex particles (1) exceeds 300 μm, it will be impossible to manufacture microcapsules with small particle sizes. The suitable upper limit of the average particle size of the latex particles (1) is 100 μm, and the preferred upper limit is 50 μm. Furthermore, the average particle size of the latex particles of latex (1) and latex (2) refers to the average particle size of the droplets measured by a microscope or the like. However, when the average particle size of the latex particles is less than 1 μm, it means that the average particle size of the droplets is obtained by a particle size distribution measuring device or the like.

[0054] The average particle size (r) of the latex particles (2) formed by the above-mentioned latex (2) should preferably be less than 10% of the average particle size (R) of the latex particles (1) formed by the above-mentioned latex (1) (i.e., r / R≦0.1), specifically 0.01~30μm, preferably 0.01~10μm. If the average particle size ratio (r / R) exceeds 0.1, the polymerization reaction caused by the latex particles (2) and latex particles (1) merging into one will not be preferential, resulting in the latex particles (1) merging into each other or the latex particles (2) merging into each other, thus affecting the performance of the microcapsule itself, which is not suitable.

[0055] The latex particles (2) of the latex (2) of the present invention can also be produced by conventional inkjet printing. For example, the latex particles (2) of the present invention can be ejected by using a piezoelectric inkjet nozzle, thereby combining them with the aforementioned latex particles (1).

[0056] The latex forming step of the present invention is suitable for either O / W or W / O type, but for the purpose of stabilizing and preserving the latex particles (2) of the latex (2), O / O' is preferable, as O' has a higher viscosity than water. Higher viscosity inhibits the aggregation of latex particles (2) and promotes their aggregation with latex particles (1). Furthermore, a higher interfacial tension of the latex (2) makes it less susceptible to deformation, which promotes its aggregation with the latex particles (1) of the latex (1), and is therefore suitable.

[0057] Regarding oil phase solvents, when using aliphatic hydrocarbon systems, the more carbon atoms, the more stable the droplets, and therefore the more suitable they are.

[0058] The membrane (shell) of the microcapsule in this invention preferably contains polyurethane or polyurea derived from the polyisocyanate structure.

[0059] The average shell (membrane) thickness of the microcapsules of the present invention has a suitable lower limit of 0.01 μm and a suitable upper limit of 5.0 μm. If the average shell thickness is less than 0.01 μm, the retention of the core agent decreases. If the average shell thickness exceeds 5.0 μm, the release of the water-soluble core agent decreases. The preferred lower limit of the average shell thickness is 0.08 μm and the preferred upper limit is 1.0 μm.

[0060] The average shell thickness refers to the average value of the wall thickness (μm) of 10 microcapsules obtained by scanning electron microscopy (SEM). Specifically, the microcapsule liquid is coated onto any support and dried to form a coated film. The average shell thickness is obtained by preparing a cross-sectional section of the resulting coated film and observing the cross-section using SEM. The wall thickness of any 10 microcapsules is measured by observing their respective cross-sections, and the average value is calculated.

[0061] The polymerization reaction time for generating the microcapsules of the present invention is generally preferably about 0.5 hours to 10 hours, and more preferably about 1 hour to 6 hours. By making r / R smaller as described above, the reaction time can be reduced to less than 4 hours, which is suitable from a production perspective. In addition, the polymerization reaction time referred to herein refers to the time from the addition of latex (2) to latex (1) until the start of the washing process described later.

[0062] Furthermore, an excessively short polymerization reaction time indicates the presence of unreacted components or the termination of the reaction before sufficient film strength is achieved. On the other hand, an excessively long reaction time is associated with the following: additional reactions beyond the interface, resulting in heterogeneity between microcapsules or aggregation of microcapsules.

[0063] The resulting microcapsules may also be covered as required. The method of coated microcapsules is not specifically limited, e.g., the interfacial polymerization performed by utilizing substances that would react with the phloem former of the capsule, etc. may be cited. In the case of the above-mentioned local presence of the film-forming material on the surface of the particle, so that the substance that will react with the film-former is covered in the same way as the addition of latex (2) of the present invention. Covered microcapsules This matter is considered appropriate from the viewpoint of preventing leakage of the microcapsule core. As the amount of substance that will react with the membrane-forming material, it shall be less than the equivalent of the membrane-forming material contained in latex (2), preferably less than 1 / 10. For example, epoxy compounds may be cited as reactants relative to an amine belonging to a pellicle formant, which is less than 1 / 10 equivalent, preferably less than 1 / 50 equivalent, with respect to the hydrogen equivalent of the amine. The above epoxy compounds can be used alone or mixed with 2 or more. The timing of the addition to the reaction solution of a latex constituted by a droplet comprising a substance that will react with the pellicle formant may be arbitrarily added from the end of the addition of latex (2) of the present invention until the end of the reaction. As an appropriate timing of addition, it was appropriate to add 1 hour before the end of the reaction, preferably 30 minutes before the end of the reaction, from the point of view that a pellicle can be formed.

[0064] Also, the resulting microcapsules can also be dried by means of vacuum drying and the like after repeated washing using solvents such as water, hexane, toluene, and ethyl acetate.

[0065] In the microcapsules of the present invention, the average particle size of the final microcapsules is 0.1~4000μm, preferably 0.1~350μm, preferably 0.1~310μm. The amount of core agent in capsules smaller than 0.1μm will be reduced. Although microcapsules exceeding 400 μm can also be prepared, the advantages of using the fabrication method of the present invention will be reduced. The microcapsules of the invention can be utilized in many cores for a wide variety of applications.

[0066] [Examples] The invention is described in more detail in the following revealing embodiments, but the invention is not limited to these embodiments.

[0067] <Preparation of Microcapsules Encapsulating Aqueous Solutions> (Example 1) Two parts by weight of ethylenediamine (manufactured by Fuji Film & Television and Koh Genuine Pharmaceutical Co., Ltd.) as a monomer for forming a film were mixed and dissolved with 30 parts by weight of a 10% aqueous solution of polyvinylpyrrolidone as a water-soluble core agent to obtain solution (1). This solution (1) was added to 120 parts by weight of a paraffin-based solvent (MORESCO WHITE P-100 manufactured by MORESCO Corporation) (containing 5% by weight of SUNSOFT 818R (manufactured by Taiyo Chemical Co., Ltd.) as an emulsifier), and stirred at 550 rpm to prepare latex (1) with latex particles (1) dispersed. The droplet diameter (average particle size) of the latex particles (1) was measured by a microscope (KEYENCE VHX-6000 manufactured by KEYENCE Corporation) and was 101.5 μm.

[0068] On the other hand, 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals Co., Ltd.), a polyisocyanate that reacts with ethylenediamine to form a film, were dissolved in 30 parts by weight of ethyl acetate, and added to 600 parts by weight of a paraffin-based solvent (MORESCO WHITE P-100 manufactured by MORESCO Co., Ltd.) (containing 7% by weight of SUNSOFT 818R (manufactured by Taiyo Chemical Co., Ltd.) as an emulsifier). The mixture was stirred at 10,000 rpm using a homogenizer (MARKII manufactured by PRIMIX Co., Ltd.) to prepare a latex (2) containing latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured using a microscope (VHX-6000 manufactured by KEYENCE Co., Ltd.), it was 10.1 μm.

[0069] After the obtained latex (1) was put into a jacketed stirring reaction vessel, latex (2) was added while stirring at 250 rpm. After stirring at room temperature for 60 minutes, warm water was passed through to make the reaction solution 50°C, and the reaction was allowed to proceed at 50°C for 240 minutes. After the reaction was completed, the reaction solution was added to twice the amount of toluene, and microcapsules were obtained by vacuum filtration. The particle size (average particle size) of the microcapsules was measured to be 103.8 μm using a microscope (KEYENCE VHX-6000).

[0070] In addition, the solubility of latex particles (2) in latex particles (1) is 8.3.

[0071] The water content of the microcapsules was determined to be 62.0% by measuring the water content of the microcapsules using an infrared moisture meter (FD-720, manufactured by Kett Scientific Institute).

[0072] (Example 2) In the preparation of latex (2) with dispersed latex particles (2), the rotation speed of the homogenizer (PRIMIX MARKII) was changed to 15000 rpm, and the preparation was carried out in the same manner as in Example 1. When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (KEYENCE VHX-6000), it was 4.8 μm.

[0073] Similar to Example 1, after adding latex (2) to latex (1), the mixture was stirred at room temperature for 60 minutes, then warm water was passed through to bring the reaction solution to 50°C, and the reaction was carried out at 50°C for 150 minutes. Microcapsules were obtained in the same manner as in Example 1. The particle size (average particle size) of these microcapsules was measured to be 102.8 μm using a microscope (KEYENCE VHX-6000).

[0074] In addition, the solubility of latex particles (2) in latex particles (1) is 8.3.

[0075] The moisture content of the microcapsules was determined to be 63.0% by measuring the moisture content of the microcapsules using an infrared moisture meter (FD-720 manufactured by Kett Scientific Institute).

[0076] (Example 3) In the preparation of latex (1), the stirring speed was changed to 250 rpm, and the preparation was carried out in the same manner as in Example 1. When the droplet diameter (average particle size) of the latex particles (1) was measured by a microscope (KEYENCE VHX-6000), it was 200.7 μm.

[0077] In the same manner as in Example 1, latex (1) was added to a jacketed stirring reaction vessel, and then latex (2) of Example 1 was added while stirring at 150 rpm. After stirring at room temperature for 60 minutes, warm water was passed through to bring the reaction solution to 50°C, and the reaction was allowed to proceed at 50°C for 180 minutes. Microcapsules were obtained in the same manner as in Example 1. The particle size (average particle size) of these microcapsules was measured to be 205.3 μm using a microscope (KEYENCE VHX-6000).

[0078] The solubility of latex particles (2) in latex particles (1) is 8.3.

[0079] The moisture content of the microcapsules was determined to be 61.0% by measuring the moisture content of the microcapsules using an infrared moisture meter (FD-720 manufactured by Kett Scientific Institute).

[0080] (Example 4) Similar to Example 3, in the preparation of latex (2), the rotation speed of the homogenizer (PRIMIX MARKII) was changed to 5000 rpm, and latex (2) with latex particles (2) dispersed was prepared. When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (KEYENCE VHX-6000), it was 20.0 μm.

[0081] Similar to Example 3, after adding latex (2) to latex (1), the mixture was stirred at room temperature for 60 minutes, then warm water was passed through to bring the reaction solution to 50°C, and the mixture was allowed to react at 50°C for 300 minutes. Microcapsules were obtained in the same manner as in Example 3. The particle size (average particle size) of these microcapsules was measured to be 210.0 μm using a microscope (KEYENCE VHX-6000).

[0082] The solubility of latex particles (2) in latex particles (1) is 8.3.

[0083] The water content of the microcapsules was determined to be 60.0% by measuring the water content of the microcapsules using an infrared moisture meter (FD-720 manufactured by Kett Scientific Institute).

[0084] (Example 5) Similar to Example 1, in the preparation of solution (1), instead of ethylenediamine, it was replaced with 2 parts by weight of 1,4-butanediol (manufactured by Fuji Film & Television and Pure Chemical Industries Co., Ltd.). In the preparation of solution (2), except for adding 1.5 parts by weight of 1,4-diazabicyclo[2.2.2]octane (manufactured by Fuji Film & Television and Pure Chemical Industries Co., Ltd.) as a catalyst to a solution of 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals Co., Ltd.) and 30 parts by weight of ethyl acetate, the latex (2) was prepared in the same manner as in Example 1.

[0085] When the droplet diameter (average droplet diameter) of the droplets formed by solution (1) was measured using a microscope (VHX-6000, manufactured by KEYENCE), it was 103.0 μm. On the other hand, when the droplet diameter (average droplet diameter) of the droplets formed by solution (2) was measured using a microscope (VHX-6000, manufactured by KEYENCE), it was 10.2 μm. When the particle size (average particle size) of the obtained microcapsules was measured using a microscope (VHX-6000, manufactured by KEYENCE), it was 105.4 μm.

[0086] The moisture content of the microcapsules was determined to be 65.0% by measuring the moisture content of the microcapsules using an infrared moisture meter (FD-720, manufactured by Kett Scientific Institute).

[0087] (Comparative Example 1) Similar to Example 1, in the preparation of latex (2), 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals) were directly added to a jacketed stirred reactor in which latex (1) had been added. Although the reaction was carried out for a total of 8 hours by stirring at room temperature and stirring at 50°C, no latex (2) was formed, so no film was formed and microcapsules could not be obtained.

[0088] (Comparative Example 2) Similar to Example 1, in the preparation of latex (2), 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals) were not dissolved in ethyl acetate, and 600 parts by weight of paraffinic solvent (MORESCO WHITE P-100 manufactured by MORESCO) (containing 7% by weight of SUNSOFT 818R (manufactured by Taiyo Chemical Co., Ltd.) as an emulsifier) ​​were added. The mixture was stirred at 10,000 rpm using a homogenizer (MARKII manufactured by PRIMIX) to prepare latex (2) with dispersed latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (VHX-6000 manufactured by KEYENCE), it was 27.3 μm. The r / R ratio was 0.269.

[0089] After the obtained latex (1) was put into a jacketed stirring reaction vessel, and latex (2) was added while stirring at 250 rpm, the particles agglomerated during the reaction and could not be dispersed, so microcapsules could not be obtained.

[0090] (Comparative Example 3) Similar to Example 1, in the preparation of latex (2), 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals) were not dissolved in ethyl acetate, and 600 parts by weight of paraffin-based solvent (MORESCO WHITE P-100, manufactured by MORESCO) (containing 7% by weight of SUNSOFT 818R (manufactured by Taiyo Chemical Co., Ltd.) as an emulsifier) ​​were added. The mixture was stirred at 15,000 rpm using a homogenizer (MARKII, manufactured by PRIMIX) to prepare latex (2) with dispersed latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (VHX-6000, manufactured by KEYENCE), it was 9.8 μm.

[0091] After the obtained latex (1) was put into a jacketed stirring reaction vessel, latex (2) was added while stirring at 250 rpm. After stirring at room temperature for 60 minutes, warm water was passed through to make the reaction solution 50°C, and the reaction was carried out at 50°C. When a sample was taken during the reaction, it was 101.5 μm, but the membrane was weak. The reaction was carried out for a total of 8 hours by stirring at room temperature and stirring at 50°C. After the reaction solution was put into toluene with twice the amount of reaction solution, the microcapsules broke during vacuum filtration and became agglomerates, so microcapsules could not be obtained.

[0092] (Comparative Example 4) Similar to Example 1, in the preparation of latex (2), 30 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals) was dissolved in 30 parts by weight of ethyl acetate, and 600 parts by weight of paraffinic solvent (MORESCO WHITE P-100, manufactured by MORESCO) (containing 7% by weight of SUNSOFT 818R (manufactured by Taiyo Chemical Co., Ltd.) as an emulsifier) ​​was added, and the mixture was stirred at 5000 rpm using a homogenizer (MARKII, manufactured by PRIMIX Co., Ltd.) to prepare latex (2) with dispersed latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (VHX-6000, manufactured by KEYENCE Co., Ltd.), it was 31.3 μm. The r / R value was 0.3084.

[0093] After the obtained latex (1) was put into a jacketed stirring reaction vessel, latex (2) was added while stirring at 250 rpm. After stirring at room temperature for 60 minutes, warm water was passed through to make the reaction solution 50°C, and the reaction was carried out at 50°C for 180 minutes. After the reaction was completed, the reaction solution was put into twice the amount of toluene, and microcapsules were obtained by vacuum filtration. When the particle size (average particle size) of the microcapsules was measured by a microscope (KEYENCE VHX-6000), it was 130.3 μm. However, the water encapsulated in the microcapsules leaked out. When the water content of the microcapsules was measured by an infrared moisture meter (Kett Scientific Institute FD-720), the water content of the microcapsules was found to be 25.0%.

[0094] <Preparation of Microcapsules Encapsulating Hydrophobic Substances> (Example 6) 10 parts by weight of STABIO D-370N (manufactured by Mitsui Chemicals Co., Ltd.) as polyisocyanate, 3 parts by weight of Takenate D-262 (manufactured by Mitsui Chemicals Co., Ltd.), and 32 parts by weight of 1-benzyl-2-methylimidazolium as hydrophobic substance were mixed and dissolved to obtain solution (1). This solution (1) was added to 300 parts by weight of paraffin-based solvent (MORESCO WHITE P-100 manufactured by MORESCO Co., Ltd.) (containing 0.5% by weight of KF-6038 (manufactured by Shin-Etsu Silicone Co., Ltd.) as emulsifier), and stirred at 4500 rpm using a homogenizer (MARKII manufactured by PRIMIX Co., Ltd.) to prepare latex (1) with latex particles (1) dispersed. When the droplet diameter (average particle size) of the latex particles (1) was measured by a microscope (VHX-6000 manufactured by KEYENCE Co., Ltd.), it was 15.1 μm.

[0095] On the other hand, 4 parts by weight of hexamethylenediamine (manufactured by Fuji Film & Television and Koichi Pure Chemical Co., Ltd.) were added to 300 parts by weight of a paraffin-based solvent (MORESCO WHITE P-100 manufactured by MORESCO) (containing 0.5% by weight of KF-6038 (manufactured by Shin-Etsu Silicon Co., Ltd.) as an emulsifier), and the mixture was stirred at 8000 rpm using a homogenizer (MARKII manufactured by PRIMIX Co., Ltd.) to prepare a latex (2) containing latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (VHX-6000 manufactured by KEYENCE Co., Ltd.), it was 1.5 μm.

[0096] After the obtained latex (1) was added to a jacketed stirring reaction vessel, latex (2) was quickly added while stirring at 250 rpm. After stirring at room temperature for 60 minutes, warm water was passed through to bring the reaction solution to 50°C, and the reaction was allowed to proceed at 50°C for 150 minutes. After the reaction was completed, the reaction solution was added to twice the amount of hexane, and microcapsules were obtained by vacuum filtration. The particle size (average particle size) of the microcapsules was measured to be 15.8 μm using a microscope (KEYENCE VHX-6000).

[0097] (Example 7) Microcapsules were obtained by making the following changes to Example 6. Microcapsules were obtained in the same manner as in Example 2, except that latex (1) was added to a jacketed stirred reaction vessel and stirred at 250 rpm for 90 minutes. In addition, when adding latex (2), the average particle size was measured every 10 minutes after adding latex (1) to the jacketed stirred reaction vessel. It was confirmed that the dispersion value (standard deviation) had not increased and the droplet diameter (average particle size) was 19.2 μm before adding latex (2).

[0098] After the reaction was completed, the particle size (average particle size) of the microcapsules was measured by a microscope (KEYENCE VHX-6000), and it was 19.8 μm.

[0099] (Example 8) Microcapsules were obtained by making the following changes to Example 6. In the preparation of latex (1), instead of using a homogenizer (PRIMIX MARKII) to stir at 4500 rpm, a Three-one motor was used to change the rotation speed to 400 rpm, and latex (1) with latex particles (1) dispersed was prepared. When the droplet diameter (average particle size) of the latex particles (1) was measured by a microscope (KEYENCE VHX-6000), it was 98.5 μm.

[0100] In the preparation of latex (2) in Example 6, the rotation speed of the homogenizer (PRIMIX MARKII) was changed to 2000 rpm, and microcapsules were obtained in the same manner as in Example 6, except that the latex (2) containing the latex particles (2) was prepared. In addition, when the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (KEYENCE VHX-6000), it was 7.8 μm.

[0101] After the reaction was completed, the particle size (average particle size) of the microcapsules was measured by a microscope (KEYENCE VHX-6000), which was 105.0 μm.

[0102] (Comparative Example 5) In the preparation of latex (2) in Example 6, a homogenizer (PRIMIX MARKII) was used to stir at 4000 rpm to prepare latex (2) with dispersed latex particles (2). When the droplet diameter (average particle size) of the latex particles (2) was measured by a microscope (KEYENCE VHX-6000), it was 3.0 μm. It was reacted in the same manner as in Example 6 to obtain microcapsules. The r / R value was 0.1987.

[0103] When the particle size (average particle size) of this microcapsule was measured by a microscope (KEYENCE VHX-6000), it was 22.0 μm.

[0104] <Evaluation> Hardness test (pressure resistance) The pressure resistance of the microcapsules obtained in Examples 6, 7, 8 and Comparative Example 5 was evaluated using commercially available degreasing paper as follows.

[0105] With a microcapsule supported on top of commercially available degreasing paper, degreasing paper was also supported on the upper side. Using the hardness mode of a small benchtop testing machine, Eztest (manufactured by Shimadzu Corporation), the following pressure was determined: the pressure at which the hydrophobic material encapsulated in the microcapsule permeates into the degreasing paper and is absorbed by the degreasing paper (permeation can be felt) when the indentation becomes imperceptible. The pressure at which permeation becomes imperceptible was determined (recorded as pressure resistance). The results are shown in Table 1.

[0106] [Table 1] Example 6 Example 7 Example 8 Comparative Example 5 Pressure resistance / N 30 30 20 5

[0107] It is understood that the microcapsules of the present invention have excellent resistance to pressure because each particle is uniform and consistent. Therefore, the encapsulated material is less likely to leak out due to pressure.

[0108] <Preparation of the microcapsule containing the epoxy resin adduct> (Example 9) Preparation of adduct A: 17.2 parts by weight of 1-benzyl-2-methylimidazolium, 6.33 parts by weight of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation jER828), and 20 ml of methyl ethyl ketone were stirred at 30°C for more than 1 hour to prepare adduct A.

[0109] In Example 6, the hydrophobic substance, 1-benzyl-2-methylimidazole, was replaced with 32 parts by weight of the above-mentioned adduct, and microcapsules were obtained in the same manner as in Example 6. The particle size R of the latex particles (1) was 15.1 μm, and the particle size r of the latex particles (2) was 1.5 μm. Therefore, the value of r / R was 0.0993.

[0110] (Example 10) <Preparation of Additive B> 5.80 parts by weight of 2-methylimidazole, 4.47 parts by weight of bisphenol A epoxy resin (Mitsubishi Chemical Corporation jER828), and 80 ml of methyl ethyl ketone were stirred at 30°C for more than 1 hour and then allowed to return to room temperature to prepare additive B.

[0111] In Example 6, instead of the hydrophobic substance 1-benzyl-2-methylimidazole, 32 parts by weight of the above-mentioned adduct B were used to obtain microcapsules in the same manner as in Example 6. The particle size R of the latex particles (1) was 15.1 μm, and the particle size r of the latex particles (2) was 1.3 μm. Therefore, the value of r / R was 0.0861.

[0112] (Example 11) <Preparation of adduct C> 10.2 parts by weight of 2-phenylimidazolium, 4.47 parts by weight of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation jER828), and 80 ml of methyl ethyl ketone were stirred at 30°C for more than 1 hour and then allowed to return to room temperature to prepare adduct C.

[0113] In Example 6, the hydrophobic substance 1-benzyl-2-methylimidazole was replaced with 32 parts by weight of the above-mentioned adduct C, and microcapsules were obtained in the same manner as in Example 6. The particle size R of the latex particles (1) was 15.1 μm, and the particle size r of the latex particles (2) was 1.4 μm. Therefore, the value of r / R was 0.0927.

[0114] It is understood that the microcapsules of the present invention have better storage stability than when a hardener is used alone by microencapsulation. By further making the encapsulating material an epoxy resin adduct, the storage stability will be greatly improved.

[0115] The following are recorded in Table 2: the particle size (R μm) of latex (1) in the Examples and Comparative Examples, the particle size (r μm) of latex (2), the r / R value, the solubility (%) of latex particles (2) in latex particles (1), the particle size (μm) of the obtained microcapsules, and the moisture content (%) of the obtained microcapsules. [Table 2] r (μm) R(μm) r / R solubility (%) Capsule particle size (μm) Moisture content (%) Example 1 10.1 101.5 0.0995 8.3 103.8 62 Example 2 4.8 101.5 0.0473 8.3 102.8 63 Example 3 10.1 200.7 0.0503 8.3 205.3 61 Example 4 20.0 200.7 0.0997 8.3 210.0 60 Example 5 10.2 103.0 0.099 8.3 105.4 65 Example 6 1.5 15.1 0.0993 >10 15.8 Example 7 1.5 19.2 0.0781 >10 20.8 Example 8 7.8 98.5 0.0792 >10 105.0 Example 9 1.5 15.1 0.0993 >10 17.2 Example 10 1.3 15.1 0.0861 >10 17.0 Example 11 1.4 15.1 0.0927 >10 17.5 Comparative Example 1 - 101.5 - - - - Comparative Example 2 27.3 101.5 0.269 - - - Comparative Example 3 9.8 101.5 0.0966 - - - Comparative Example 4 31.3 101.5 0.3084 8.3 130.3 twenty five Comparative Example 5 3.0 15.1 0.1987 >10 22.0

Claims

1. A method for manufacturing microcapsules, characterized in that it uses two types of latex particles of different sizes to manufacture microcapsules, and the method comprises the following steps: a latex forming step, forming two types of latex (1) and (2) that are common to continuous phases, such that one of the two monomers that react with each other to form a film is contained in the latex particles (1) of latex (1), and the monomer of the other is contained in the latex particles (2) of latex (2); a microcapsule forming step, mixing latex (1) and latex (2) to polymerize their interface, wherein the average particle size (R) of the latex particles (1) of latex (1) is 0.1~300 μm, the average particle size (r) of the latex particles (2) of latex (2) is 0.01~30 μm, and r / R≦0.

1.

2. The method for manufacturing microcapsules as claimed in claim 1, wherein the average particle size (R) of latex particles (1) is 0.1 to 100 μm, the average particle size (r) of latex particles (2) is 0.01 to 10 μm, and r / R ≦ 0.

1.

3. In the method for manufacturing microcapsules as claimed in claim 1 or 2, after the latex forming step, the average particle size (R) of the latex particles (1) or the average particle size (r) of the latex particles (2) is adjusted to a predetermined range.

4. The method for manufacturing microcapsules as claimed in claim 1 or 2, wherein the increase rate of the average particle size (R) in the microcapsule formation step is less than 1.3 times.

5. A method for manufacturing microcapsules as claimed in claim 1 or 2, wherein the continuous phase is flowing paraffin or silicone oil.

6. A method for manufacturing microcapsules as claimed in claim 1 or 2, wherein one of the two monomers that react with each other to form a membrane is an isocyanate compound having two or more isocyanate groups in one molecule, and the other monomer is selected from the group consisting of: polyamine compounds having two or more amine groups in one molecule, polyhydroxy compounds having two or more hydroxyl groups in one molecule, and combinations thereof.

7. The method for manufacturing microcapsules as claimed in claim 1 or 2, wherein the core agent of the microcapsules is water, water-soluble heat storage material, thermally expandable hydrocarbon or its fluoride, epoxy resin curing agent or epoxy resin curing accelerator.

8. The method for manufacturing microcapsules as claimed in claim 7, wherein the aforementioned epoxy resin curing agent comprises polyisocyanate, bisphenol A type epoxy resin, and imidazole compound.

9. The method for manufacturing microcapsules as claimed in claim 7, wherein the aforementioned epoxy resin curing agent is a liquid mixture of premixed polyisocyanate, bisphenol A type epoxy resin and imidazole compound, which is then heated and stirred.

10. The method for manufacturing microcapsules as claimed in claim 1 or 2, wherein the reaction time of the microcapsule formation step is within 6 hours.