Functional particles and method for producing the same

Abstract

An object of the present invention is to improve the storage stability of functional particles. [Solution] The functional particle has a core-shell structure and includes a core portion made of a functional substance and a shell portion made of a resin that covers the core portion, the core portion being a nanoparticle.

Description

[Technical field]

[0001] The present invention relates to a functional particle and a method for producing the same. [Background technology]

[0002] 2. Description of the Related Art Various techniques have been proposed for imparting various functions possessed by functional substances, for example, photocatalytic substances, ultraviolet shielding materials, functional coloring materials such as leuco dyes, latent heat storage materials, and the like, to objects.

[0003] However, these functional substances are rarely applied in their original form, and various forms have been devised to impart weather resistance, durability, storage stability, etc. to the functional substances.

[0004] For example, Patent Document 1 proposes a method of dissolving a tackifier in an ethylenically unsaturated monomer and carrying out emulsion polymerization to modify the acrylic resin with a tackifier and make it present in the acrylic resin when producing a water-based acrylic resin in order to solve the poor adhesion of the acrylic resin to polyolefin. Patent Document 2 also proposes core-shell type composite particles suitable for use in producing pigments, paints, cosmetics, ultraviolet shielding materials, optical materials, and electronics materials. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 58-185668 [Patent Document 2] JP 2014-101303 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, Patent Document 1 discloses a method of dissolving a tackifier resin in an ethylenically unsaturated monomer and carrying out emulsion polymerization, but this method may generate a large amount of coarse particles of 2 μm or more containing a high concentration of the tackifier resin during polymerization, and these may settle during storage. In addition, Patent Document 2 only mixes a functional substance into the core resin particles constituting the core layer of the core-shell composite particles or into the resin monomer liquid constituting the shell layer, but has a problem with the ability to sustainably retain the functional substance in the core-shell composite particles.

[0007] Therefore, an object of the present invention is to improve the storage stability of functional particles. [Means for solving the problem]

[0008] In order to achieve the object of the present invention, the functional particle of the present invention has the following configuration: That is, the functional particle has a core-shell structure, and includes a core portion made of a functional material and a shell portion made of a resin covering the core portion, and the core portion is a nanoparticle. The resin contains, as constituent units, 80 to 95% by mass of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, 80 to 95% by mass of an alicyclic alkyl group-containing unsaturated monomer, or 80 to 95% by mass of an aromatic group-containing unsaturated monomer, and 2 to 20% by mass of a carboxy group-containing ethylenically unsaturated monomer, relative to 100% by mass of all polymerizable monomers, and the functional substance is any one of a tackifier, polylactic acid, and a functional dye. Effect of the Invention

[0009] According to the present invention, the storage stability of the functional particles can be improved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 shows an example of a SEM image of a seed particle according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of an SEM image of a functional particle according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following embodiments are described in detail. Note that the following embodiments do not limit the scope of the invention, and not all of the combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined in any combination.

[0012] In this specification, the expression "A to B" expressing a range of numerical values ​​is synonymous with "A or more" and "B or less," and includes A and B.

[0013] <Functional particles> The core-shell structured functional particle according to one embodiment includes a core made of a functional material and a shell made of a resin covering the core. The core-shell structure of the functional particle allows a high concentration of the functional material to be stably trapped in the core, so that the functionality of the functional material (hereinafter, sometimes simply referred to as "function") is exhibited more effectively than ever before. Conventionally, the monomers that can be used in the production of functional particles were limited. Conventionally available monomers are, for example, aromatic group-containing unsaturated monomers that can dissolve the functional material. On the other hand, in the present invention, the functional particles have a core-shell structure, so that there is no restriction on the type of monomer that can be used. According to the present invention, a monomer that does not easily dissolve the functional material can also be used in the production of functional particles.

[0014] The functional particles according to one embodiment are nanoparticles. The functional particles may be particles having a size on the order of nanometers (nm). The average particle diameter of the functional particles according to one embodiment is 60 to 1000 nm, preferably 60 to 500 nm, and more preferably 150 to 350 nm. The average particle diameter of the functional particles is a particle diameter (D50; median diameter) at a cumulative 50% in a volume-based particle size distribution measured by a dynamic light scattering method.

[0015] <Core> The core part is substantially made of a functional material, but may contain a material that is unavoidable in producing a functional particle. The core part according to one embodiment is a nanoparticle. Here, the core part may be a particle having a size on the order of nanometers (nm).

[0016] The average particle diameter of the core part according to one embodiment is 50 to 500 nm, preferably 50 to 300 nm, and more preferably 100 to 300 nm. The average particle diameter of the core part is a particle diameter at a cumulative 50% (D50; median diameter) in a volume-based particle size distribution measured by a dynamic light scattering method.

[0017] In one embodiment, the functional substance is contained in 100% by mass of the functional particles in an amount of 5 to 95% by mass, preferably 5 to 85% by mass, and more preferably 30 to 85% by mass.

[0018] (Functional substance) The functional substance is preferably a water-insoluble compound. Examples of the functional substance include functional dyes such as leuco dyes and fluorescent dyes, salt hydrates, paraffins, latent heat storage materials made of organic compounds, and waxes made of fatty acid esters and aliphatic hydrocarbons. In addition, polylactic acid, which is a biodegradable material from the viewpoint of carbon neutrality, and rosin-based tackifiers can also be considered as functional substances.

[0019] In one embodiment, the functional substance is any one of a tackifier, polylactic acid, a latent heat storage material, and a functional dye. The functional dye is a dye that absorbs light, emits light, undergoes a chemical change, or undergoes a physical change due to external light, heat, electricity, pressure, electric field, etc. The functional dye includes, for example, a fluorescent dye.

[0020] Here, we will take a detailed look at fluorescent dyes as one type of functional substance. A fluorescent dye is a dye that emits fluorescence. When a fluorescent dye absorbs light, the electrons in the dye are excited, and when they return to their ground state, they release excess energy as electromagnetic waves. This electromagnetic wave is fluorescence, and the wavelength of the fluorescence is always longer than the wavelength of the absorbed light (excitation light). The difference between the wavelength of the excitation light and the wavelength of the fluorescence is called the Stokes shift, and the larger this difference is, the easier it is to distinguish the fluorescence from the excitation light, making the dye easier to detect.

[0021] Examples of the fluorescent dye include compounds and derivatives having fluorescent properties such as merocyanine, perylene, acridine, anthracene, perylene, luciferin, pyranine, stilbene, rhodamine, coumarin, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), pyrromethene, fluorescein, umbelliferone, and tetraphenylethylene, and one or more selected from the above group can be used. The fluorescent dye is preferably anthracene.

[0022] In addition, there is a type of fluorescent dye called an aggregation-induced luminescent dye. An aggregation-induced luminescent dye is a fluorescent dye that does not emit light in a dilute solution state, but emits strong light in a solid or aggregated state, and shows the opposite behavior to that of general fluorescent dyes. In other words, an aggregation-induced luminescent dye is a dye that makes it possible to achieve high concentrations and high brightness, which are difficult to achieve with general fluorescent dyes due to concentration quenching, etc.

[0023] Examples of the aggregation-induced luminescent dye include silole ring-containing compounds and derivatives such as 1,1-dimethyl-2,3,4,5-tetraphenylsilole, 1,1,2,3,4,5-hexaphenylsilole, 1,1-dimethyl-2,5-dianisyl-3,4-diphenylsilole, and 1,1-diallyl-2,3,4,5-tetraphenylsilole, hydrocarbon aromatic compounds and derivatives such as tetraphenylethylene, heteroaromatic compounds and derivatives, and rhodamine compounds and derivatives, and one or more selected from the above group can be used. The aggregation-induced luminescent dye is preferably tetraphenylethylene.

[0024] In addition, polylactic acid will be described in detail as another functional material. Polylactic acid is a polymer obtained by polymerizing lactic acid, and is a polymer in which lactic acid is polymerized by ester bonds. Lactic acid is obtained by fermenting sugars such as glucose and sugar with lactic acid bacteria. Sugars, which are the raw material for lactic acid, can be obtained by extraction from sugarcane, etc., or by applying enzymes to starch obtained from corn, potato, sweet potato, rice, wheat, etc. In this way, polylactic acid is a plant-derived biomass material synthesized using plants as a starting material, which are biomass. Polylactic acid is also hydrolyzed by moisture in the environment to low molecular weight, and has the property of being decomposed into carbon dioxide and water by microorganisms, etc. (biodegradability). At this time, carbon dioxide is released into the atmosphere, but since plants absorb carbon dioxide in the atmosphere to synthesize starch, polylactic acid is said to be carbon neutral because it does not increase the amount of carbon dioxide, which is considered to be a cause of global warming, overall.

[0025] Since a lactic acid molecule has one asymmetric carbon, it has two optical isomers, namely, D-lactic acid and L-lactic acid, and the mixture of them, racemic DL-lactic acid, exhibits properties different from optically active isomers. Lactide and polylactic acid synthesized from these lactic acids also have optical isomers, and polylactic acid has various structural isomers with different properties depending on the composition of the optically isomeric lactic acid units. For example, those having only D-lactic acid as a constituent unit by polymerizing only D-lactic acid and those having only L-lactic acid as a constituent unit by polymerizing only L-lactic acid are optically active and are called poly-D-lactic acid (PDLA) and poly-L-lactic acid (PLLA), respectively. Also, those having racemic DL-lactic acid as a constituent unit are called poly-DL-lactic acid (PDLLA) and are optically inactive. From the viewpoint of polymer structure, PDLA and PLLA have an isotactic structure and exhibit crystallinity by forming a helical structure, while PDLLA has an atactic structure and is amorphous and glassy at room temperature. In addition, for example, when PLLA and PDLA are mixed in a 1:1 ratio, a different crystal is formed, and it is called stereocomplex polylactic acid (SC-PLA), and it is known that the helical structures interlock well to form a resin with high heat resistance.

[0026] In addition, as another functional substance, a tackifier will be described in detail. A tackifier is generally called a tackifier resin. For example, a tackifier resin may be used to improve the biomass ratio of a removable pressure-sensitive adhesive composition, and from the viewpoint of improving the biomass ratio, it is preferable to use a rosin-based resin, a terpene-based resin, or the like.

[0027] Examples of rosin-based resins include natural rosin, rosin ester, hydrogenated rosin, hydrogenated rosin ester, polymerized rosin, polymerized rosin ester, disproportionated rosin, and disproportionated rosin ester.

[0028] Examples of terpene resins include α-pinene resins, β-pinene resins, terpene resins, hydrogenated terpene resins, aromatic modified terpene resins, and terpene phenol resins. Among these tackifier resins, natural rosin and ester resins derived from the rosin (rosin esters, water-added rosin esters), etc. are more preferred.

[0029] As another functional substance, the latent heat storage material will be described in detail. Examples of the latent heat storage material include aliphatic hydrocarbons, fatty acids, fatty acid esters, fatty acid ethers, and aliphatic alcohols. Among them, from the viewpoints of ease of temperature setting according to the purpose of use and high stability (long life), it is preferable that the latent heat storage material contains at least one selected from the group consisting of aliphatic hydrocarbons and fatty acid esters. The latent heat storage material is preferably butyl stearate and methyl stearate 95.

[0030] Examples of the aliphatic hydrocarbon include linear aliphatic hydrocarbons such as n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-docosane, and other n-paraffins; petroleum-derived hydrocarbon waxes such as paraffin wax and microcrystalline wax; and synthetic hydrocarbon waxes such as polyethylene wax and Fischer-Tropsch wax. The linear aliphatic hydrocarbon (n-paraffin) preferably has 8 to 40 carbon atoms, more preferably 12 to 40 carbon atoms, and even more preferably 14 to 40 carbon atoms. The various waxes (hydrocarbon waxes) can also be used as supercooling inhibitors. It is preferable to use the supercooling inhibitor (hydrocarbon wax) in combination with other latent heat storage materials as latent heat storage materials, and it is more preferable to use a hydrocarbon wax in combination with a fatty acid ester as a latent heat storage material.

[0031] The above-mentioned paraffin wax is a wax that is solid at room temperature (20°C ± 15°C) and is mainly produced by separating and refining from the vacuum distillation distillate oil portion of petroleum, and is mainly composed of n-paraffin. The melting point of the paraffin wax is preferably 40 to 70°C. The above-mentioned microcrystalline wax is a wax that is solid at room temperature and is mainly produced by separating and refining from the vacuum distillation residual oil portion of petroleum, and is mainly composed of branched aliphatic hydrocarbons (isoparaffins) and / or alicyclic hydrocarbons (cycloparaffins). The melting point of the microcrystalline wax is preferably 60 to 90°C. The melting point of the above-mentioned synthetic hydrocarbon wax is preferably 40 to 130°C.

[0032] As the fatty acid, for example, a fatty acid having 8 to 30 carbon atoms can be used. Fatty acids can be roughly classified into linear saturated fatty acids, linear unsaturated fatty acids, branched saturated fatty acids, and branched unsaturated fatty acids, and among these, linear saturated fatty acids are preferred. Examples of linear saturated fatty acids include octanoic acid, nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid, docosanoic acid, tetracosanoic acid, and hexacosanoic acid. Among these, linear saturated fatty acids having 10 to 18 carbon atoms are more preferred because of their ease of availability. In addition, linear saturated fatty acids having a melting point in the range of 15 to 70°C are more preferred.

[0033] As the fatty acid ester, for example, a fatty acid ester having 8 to 30 carbon atoms can be used, and a fatty acid ester having a melting point in the range of 10 to 30° C. can be preferably used. Suitable fatty acid esters include, for example, vinyl stearate, dimethyl sebacate, butyl stearate, isopropyl stearate, isopropyl palmitate, and propyl palmitate. Among these, methyl, ethyl, propyl, or butyl esters of linear saturated fatty acids having 10 to 18 carbon atoms are more preferred in terms of availability.

[0034] As the fatty acid ether, for example, a fatty acid ether having 14 to 60 carbon atoms can be used, and a fatty acid ether having a melting point in the range of −10 to 70° C. can be preferably used. Suitable fatty acid ethers include, for example, heptyl ether, octyl ether, tetradecyl ether, and hexadecyl ether.

[0035] The aliphatic alcohol may, for example, have 8 to 60 carbon atoms, and preferably has a melting point in the range of 15 to 80° C. Suitable aliphatic alcohols include, for example, 2-dodecanol, 1-tetradecanol, 7-tetradecanol, 1-octadecanol, 1-eicosanol, and 1,10-decanediol.

[0036] <Shell part> The shell portion is a resin that covers the core portion. In one embodiment, the resin contains at least one of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, an alicyclic alkyl group-containing unsaturated monomer, and an aromatic group-containing unsaturated monomer as a constituent unit. In one embodiment, the resin contains, relative to 100% by mass of all polymerizable monomers, any of 80 to 95% by mass of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, 80 to 95% by mass of an alicyclic alkyl group-containing unsaturated monomer, 80 to 95% by mass of an aromatic group-containing unsaturated monomer, and 80 to 95% by mass of a crosslinkable monomer, and 2 to 20% by mass of a carboxy group-containing ethylenically unsaturated monomer as a constituent unit.

[0037] As used herein, the term "(meth)acrylic" refers to both "acrylic" and "methacrylic." Additionally, the term "(meth)acrylate" refers to both "acrylate" and "methacrylate."

[0038] Examples of the aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. These may be used alone or in combination of two or more. The unsaturated monomer containing a linear or branched aliphatic alkyl group having 1 to 18 carbon atoms is preferably methyl methacrylate.

[0039] The content of the linear or branched unsaturated monomer containing an aliphatic alkyl group having 1 to 18 carbon atoms according to one embodiment is 80 to 95 mass %, preferably 85 to 95 mass %, based on 100 mass % of all polymerizable monomers.

[0040] Examples of the alicyclic alkyl group-containing unsaturated monomer include cyclohexyl (meth)acrylate and pt-butylcyclohexyl (meth)acrylate. These may be used alone or in combination of two or more. The alicyclic alkyl group-containing unsaturated monomer is preferably cyclohexyl methacrylate.

[0041] The content of the alicyclic alkyl group-containing unsaturated monomer according to one embodiment is 80 to 95% by mass, preferably 85 to 95% by mass, based on 100% by mass of all polymerizable monomers.

[0042] Examples of the aromatic group-containing unsaturated monomer include styrene, methylstyrene, chlorostyrene, methoxystyrene, α-methylstyrene, p-nitrostyrene, ethylvinylbenzene, vinylnaphthalene, benzyl acrylate, benzyl methacrylate, phenylethyl acrylate, phenylethyl methacrylate, phenylpropyl acrylate, phenylpropyl methacrylate, phenylnonyl acrylate, and phenylnonyl methacrylate. These may be used alone or in combination of two or more. The aromatic group-containing unsaturated monomer is preferably styrene.

[0043] The content of the aromatic group-containing unsaturated monomer according to one embodiment is 80 to 95% by mass, and preferably 85 to 95% by mass, based on 100% by mass of all polymerizable monomers.

[0044] The unsaturated monomer having a functional group is a monomer that can be copolymerized with the hydrophobic group-containing unsaturated monomer. The resin according to one embodiment contains at least one of a carboxyl group-containing ethylenically unsaturated monomer, a hydroxyl group-containing ethylenically unsaturated monomer, an amino group-containing ethylenically unsaturated monomer, an amide group-containing ethylenically unsaturated monomer, and a sulfonic acid group-containing unsaturated monomer as a structural unit as the ethylenically unsaturated monomer having a functional group. The unsaturated monomer having a functional group is preferably a carboxyl group-containing ethylenically unsaturated monomer.

[0045] Here, when the resin of the functional particles has a carboxy group, the carboxy group tends to be present on the surface of the resin. When the carboxy group is present on the surface of the resin, the dispersion stability of the functional particles is improved due to electrostatic repulsion between the carboxy groups generated between the functional particles.

[0046] Examples of the unsaturated monomer having a functional group include carboxyl group-containing ethylenically unsaturated monomers such as (meth)acrylic acid, acrylic acid dimer, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and other hydroxyalkyl (meth)acrylates reacted with maleic anhydride, succinic anhydride, and phthalic anhydride; hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxyethyl (meth)acrylate, 2-(3-)hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and glycerol. Examples of the monomer include hydroxyl group-containing ethylenically unsaturated monomers such as 2-aminoethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-aminopropyl (meth)acrylate, and 2-butylaminoethyl (meth)acrylate; amide group-containing ethylenically unsaturated monomers such as (meth)acrylamide, N-methylolacrylamide, and N-butoxymethyl (meth)acrylamide; and sulfonic acid group-containing monomers such as sodium vinylsulfonate and sodium styrenesulfonate. These may be used alone or in combination of two or more. The unsaturated monomer having a functional group is preferably a carboxyl group-containing ethylenically unsaturated monomer. The carboxyl group-containing ethylenically unsaturated monomer is preferably methacrylic acid.

[0047] The content of the unsaturated monomer having a functional group according to one embodiment is 2 to 20 mass %, 3 to 16 mass %, and preferably 3 to 14 mass %, based on 100 mass % of all polymerizable monomers.

[0048] The crosslinkable monomer is a monomer having two or more polymerizable double bonds (i.e., a polyfunctional monomer) that can crosslink the resin. Examples of the crosslinkable monomer include allyl (meth)acrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, butanediol diacrylate, butanediol dimethacrylate, neopentyl glycol dimethacrylate, hexanediol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetramethacrylate, and divinylbenzene. These may be used alone or in combination of two or more. The crosslinkable monomer is preferably trimethylolpropane trimethacrylate.

[0049] The content of the crosslinkable monomer according to one embodiment is 80-95% by mass, preferably 85-95% by mass, based on 100% by mass of the total polymerizable monomers. When the resin contains the above-mentioned predetermined amount of the crosslinkable monomer, the solvent resistance of the resin can be further improved, and swelling of the resin in a solvent can be suppressed. Solvent resistance refers to the difficulty of eluting a functional substance out of the resin.

[0050] <Method of manufacturing functional particles> A method for producing functional particles having a core-shell structure, which includes a core made of a functional material and a shell made of a resin covering the core, is described below. In one embodiment, the method for producing functional particles includes a step of generating a core by stirring a mixture of a functional material dissolved in a solvent, a surfactant, and an aqueous dispersion medium, and a step of generating a shell made of a resin covering the core by polymerizing a polymerizable monomer in the presence of the core. The method for producing functional particles having a core-shell structure includes a step of generating fine particles of a functional material (hereinafter also referred to as "seed particles") that will become the core (hereinafter also referred to as the first step), and a step of polymerizing a resin that will become the shell (hereinafter also referred to as the second step). According to the method for producing functional particles of the present invention, functional particles having a sharp particle size distribution can be obtained, and the recovery rate of the solid content of the functional particles can be improved. The functional particles of the present invention are as described above, so a detailed description of the functional particles will be omitted.

[0051] <1st process> Step 1 (a step of generating seed particles) includes a step of dissolving a functional material in a solvent (hereinafter also referred to as step 1A), a step of stirring a mixture of the functional material solution to which a surfactant and an aqueous dispersion medium have been added (hereinafter also referred to as step 1B), and a step of removing the solvent from the mixture (hereinafter also referred to as step 1C).

[0052] In the step 1A, the solvent for dissolving the functional material is an organic solvent. Examples of the organic solvent include ethers such as ethyl ether and isopropyl ether; alcohols such as methanol and ethanol; methylene chloride; ethylene dichloride; chloroform; carbon tetrachloride; ethyl acetate; methyl acetate; methyl ethyl ketone; cyclohexane; cyclopentane; tetrahydrofuran (THF); toluene; hexane; heptane, etc. These may be used alone or in combination of two or more. The solvent is preferably ethyl acetate.

[0053] In step 1B, the surfactant is used to form the functional material into fine particles in the aqueous dispersion medium. The surfactant includes, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. These may be used alone or in combination of two or more. The surfactant is preferably an anionic surfactant.

[0054] Examples of anionic surfactants include fatty acid salts such as sodium stearate, alkyl sulfates such as sodium lauryl sulfate, polyoxyalkylene alkyl ether sulfates such as sodium polyoxyethylene alkyl ether sulfate, alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate, sodium dialkyl sulfosuccinate, sodium alkyl diphenyl ether disulfonate, and ammonium polyoxyalkylene alkenyl ether sulfate. These may be used alone or in combination of two or more.

[0055] Examples of cationic surfactants include alkyltrimethylammonium salts, alkyltriethylammonium salts, dialkyldimethylammonium salts, dialkyldiethylammonium salts, and N-polyoxyalkylene-N,N,N-trialkylammonium salts, which may be used alone or in combination of two or more.

[0056] Examples of amphoteric surfactants include alkyldimethylamine oxides and alkylcarboxybetaines, which may be used alone or in combination of two or more.

[0057] Examples of nonionic surfactants include polyoxyethylene alkyl ethers [polyoxyethylene lauryl ether (manufactured by Kao, Emulgen 109P, cloud point 83° C., HLB 13.6), polyoxyethylene isodecyl ether (manufactured by Daiichi Kogyo Seiyaku, Noigen SD-80, cloud point 80° C., HLB 14.3), polyoxyalkylene branched decyl ether (manufactured by Daiichi Kogyo Seiyaku, Noigen XL-100, cloud point 79° C., HLB 14.7), polyoxyethylene tridecyl ether (manufactured by Daiichi Kogyo Seiyaku, Noigen TDS-80, cloud point 60° C., HLB 13.3), polyoxyalkylene tridecyl ether (manufactured by Daiichi Kogyo Seiyaku, Noigen TDX-50, cloud point 37° C., HLB 14.7), polyoxyethylene ...DX-50, cloud point 37° C., HLB 1 C6-20 alkyl ethers such as polyoxyethylene oleyl ether (Kao Corporation, Emulgen 409PV, cloud point 55°C, HLB 9.0), polyoxyethylene styrenated phenyl ether (Dai-ichi Kogyo Seiyaku, Noigen EA-137, cloud point 65°C, HLB 13.0), and polyoxyethylene C6-20 alkylene alkenyl ethers having at least one ethylenically unsaturated group (polymerizable unsaturated group) such as an allyl group (Kao Corporation, Latemul PD-420, cloud point 83°C, HLB 12.6), (Kao Corporation, Latemul PD-430, cloud point 95°C, HLB 14.4). These may be used alone or in combination of two or more.

[0058] In step 1B, examples of the aqueous dispersion medium include pure water and ion-exchanged water. These may be used alone or in combination of two or more. The aqueous dispersion medium is preferably ion-exchanged water.

[0059] In step 1B, existing microemulsification technology and subcritical water emulsification technology can be used to stir the mixture. Existing microemulsification technology includes a rotary stirrer using a stirring blade, an ultrasonic homogenizer, and a high-pressure homogenizer. The means for stirring the mixture is preferably an ultrasonic homogenizer.

[0060] In Step 1C, examples of the method for removing the solvent in the mixture include a method in which the mixture is heated and stirred in a water bath and a method using a reduced pressure distillation apparatus.

[0061] <Second process> The second step (a step of producing functional particles) includes a step of producing a resin shell portion covering the core portion by polymerizing a polymerizable monomer in the presence of a core portion made of a functional substance (hereinafter also referred to as step 2A), and a step of extracting functional particles having a predetermined average particle size from the functional particles using centrifugation (hereinafter also referred to as step 2B).

[0062] The method for synthesizing the resin includes, for example, emulsion polymerization, miniemulsion polymerization, and microemulsion polymerization. In step 2A, the method for synthesizing the resin is preferably emulsion polymerization, and more preferably seed emulsion polymerization.

[0063] The polymerization initiator may be any one capable of initiating radical polymerization, and any conventionally known polymerization initiator may be used.

[0064] Examples of the polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; oils such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile. Soluble azo compounds; 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxyethyl)]propionamide}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxybutyl)]propionamide}, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl) propane] and its salts, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] and its salts, 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane] and its salts, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} and its salts, 2,2'-azobis(2-methylpropionamidine) and its salts, Examples of the water-soluble azo compounds include 2,2'-azobis(2-methylpropynamidine) and its salts, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] and its salts, and organic peroxides such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butyl peroxy-2-ethylhexanoate, and t-butyl peroxyisobutyrate. These may be used alone or in combination of two or more.

[0065] In step 2B, for example, an ultracentrifuge can be used to extract functional particles having a predetermined average particle size from the functional particle emulsion. By carrying out step 2B, monodisperse functional particles with a sharp particle size distribution can be obtained, and impurities other than the functional particles can be eliminated. The ultracentrifuge is one example of a means for extracting functional particles, and is not limited thereto.

[0066] A method for producing functional particles according to one embodiment includes a step of polymerizing a polymerizable monomer in the presence of a core portion made of a functional substance to produce a shell portion of a resin that covers the core portion.

[0067] The method for producing functional particles according to one embodiment further includes a step of generating a core portion by stirring a mixture in which a surfactant and an aqueous dispersion medium are added to a functional substance dissolved in a solvent.

[0068] The method for producing a functional particle according to an embodiment further includes a step of removing the solvent after the step of producing the core portion.

[0069] The method for producing functional particles according to one embodiment further includes, after the step of generating the shell portion, a step of extracting functional particles having a predetermined average particle size from the functional particles using centrifugation.

[0070] The solvent according to one embodiment includes an organic solvent.

[0071] The surfactant according to an embodiment includes an anionic surfactant. The content of the surfactant according to an embodiment is 0.5 to 10 parts by mass with respect to 100 parts by mass of the resin.

[0072] <Production of functional particles> Table 1 shows the raw material blends and test results of the functional substance fine particles (hereinafter, seed particles) of Production Examples 1 to 8. Table 2 shows the raw material blends and test results of the functional particles of Examples 1 to 8 and Comparative Examples 1 to 5.

[0073] [Table 1] (Explanation of Abbreviations) Ultrasonic homogenizer (Mitsui Electric Seiki Co., Ltd.: UX-600 type, mixing conditions: frequency 20kHz) Average particle size (nm): Measurement method is as described in Test 1 below. Seed particle concentration (%): Solid content concentration (%) of seed particles emulsified and dispersed in water -Stability of seed particles: Confirmation method is as described in Test 2 below

[0074] [Table 2] (Explanation of Abbreviations) ST: Styrene MMA: Methyl methacrylate CHMA: Cyclohexyl methacrylate ·TMP: Trimethylolpropane trimethacrylate mAAc: Methacrylic acid Tackifier A: Arakawa Chemical Industry Co., Ltd. Hydrogenated rosin ester Ester gum H Softening point 68-78℃ (biomass content 95-100%) Tackifier B: Arakawa Chemical Industry's polymerized rosin ester Pencel D-135 Softening point: 130-140℃ (biomass content: 80-94%) Tackifier C: Arakawa Chemical Industry Co., Ltd. terpene phenol resin Tamanol 901 Softening point: 125-135℃ (biomass content: 65-79%) Polylactic acid A: Amorphous polylactic acid resin manufactured by Saiden Chemical Co., Ltd. Tg 47.5℃ (biomass content 95-100%) Latent heat storage material A: NOF Corp. butyl stearate (stearic acid butyl ester), melting point 23°C Latent heat storage material B: NOF Methyl Stearate 95 (Methyl Stearate) Melting point: 39°C Fluorescent dye A: Tetraphenylethylene manufactured by Tokyo Chemical Industry Co., Ltd. Fluorescent dye B: Anthracene manufactured by Tokyo Chemical Industry Co., Ltd. · Aggregate formation: This indicates that the test could not be performed due to the formation of aggregates of the functional substance. Average particle size (nm): Measurement method is as described in Test 1 below. Theoretical concentration of functional substance in particle (%): The concentration of functional substance in 100% by mass of functional particle (calculated concentration based on the following formula). Theoretical concentration of functional substance in particle (%) = 100 × functional substance (parts) / (functional substance (parts) + total monomer (parts)) Presence or absence of extra-particle precipitation of functional substances: The confirmation method is described in Test 3 below. Stability of functional particles: The confirmation method is described in Test 2 below.

[0075] <Production Example 1: Preparation of seed particle dispersion> A fine particle dispersion of a functional substance (seed particle dispersion) was prepared by the following procedure (see Table 1). (1) 2.0 parts of a functional substance (Tackifier A) and 10 parts of ethyl acetate were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This resulted in a functional substance solution. (2) 20 parts of ion-exchanged water and 0.02 parts of sodium dodecylbenzenesulfonate as an anionic surfactant were added to the functional substance solution, and emulsified (microparticulated) with an ultrasonic homogenizer. As a result, an emulsion in which the functional substance was dissolved was obtained. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid with an average particle size (D50) of 252 nm and consisting of 10% concentration of tackifier A was prepared.

[0076] <Production Example 2: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be described. Steps (1) to (3) correspond to steps (1) to (3) in Production Example 1. (1) 2.0 parts of a functional substance (Tackifier B) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid with an average particle size (D50) of 182 nm and consisting of 10% concentration of tackifier B was prepared.

[0077] <Production Example 3: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 2.0 parts of a functional substance (Tackifier C) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid with an average particle size (D50) of 215 nm and consisting of 10% concentration of tackifier C was prepared.

[0078] <Production Example 4: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 1.0 part of functional substance (polylactic acid A) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid consisting of polylactic acid A with a concentration of 5% and an average particle size (D50) of 194 nm was prepared.

[0079] <Production Example 5: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 2.0 parts of a functional substance (latent heat storage material A) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid with an average particle size (D50) of 275 nm and consisting of a 10% concentration of latent heat storage material A was prepared.

[0080] <Production Example 6: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 2.0 parts of functional substance (latent heat storage material B) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid with an average particle size (D50) of 234 nm and consisting of latent heat storage material B with a concentration of 10% was prepared.

[0081] <Production Example 7: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 0.5 parts of a functional substance (fluorescent dye A) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated. Furthermore, by removing the ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid consisting of fluorescent dye A at a concentration of 2.5% and having an average particle size (D50) of 185 nm was prepared.

[0082] <Production Example 8: Preparation of seed particle dispersion> Only the differences from Production Example 1 will be explained. (1) to (3) correspond to (1) to (3) in Production Example 1. (1) 0.5 parts of a functional substance (fluorescent dye B) was added. (2) Since this is the same as Production Example 1, the explanation will be omitted. (3) No precipitate was observed even after the emulsion was left to stand, and no functional substance was precipitated.Furthermore, by removing ethyl acetate using a vacuum distillation apparatus, a seed particle dispersion liquid consisting of fluorescent dye B at a concentration of 2.5% and having an average particle size (D50) of 164 nm was prepared.

[0083] <Example 1: Preparation of functional particles> See Table 2. Seed particles with an average particle size (D50) of 252 nm obtained in Production Example 1 were charged into a glass reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser. The temperature was raised to 80° C., and 0.025 parts of potassium persulfate was added while stirring, and a mixed solution of 0.95 parts of methyl methacrylate and 0.05 parts of methacrylic acid was added dropwise over 30 minutes. After the dropwise addition, the mixture was stirred for 3 hours at the same temperature to prepare functional particles with an average particle size (D50) of 265 nm.

[0084] The average particle size of the functional particles obtained by polymerization was determined by dynamic light scattering in the same manner as in Production Example 1. In addition, when the obtained functional particles were observed using an electron microscope, no aggregates of the functional material were observed other than the functional particles. It was confirmed that the functional material was encapsulated in the resin particles.

[0085] <Example 2: Preparation of functional particles> Only the difference from Example 1 will be described. Seed particles having an average particle size (D50) of 182 nm obtained in Production Example 2 were charged. 1.8 parts of methyl methacrylate and 0.2 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 214 nm were prepared.

[0086] <Example 3: Preparation of functional particles> Only the differences from Example 1 will be described. Seed particles having an average particle size (D50) of 215 nm obtained in Production Example 3 were charged. 0.45 parts of styrene and 0.05 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 218 nm were prepared.

[0087] <Example 4: Preparation of functional particles> Only the differences from Example 1 will be described. Seed particles having an average particle size (D50) of 194 nm obtained in Production Example 4 were charged. 0.45 parts of cyclohexyl methacrylate and 0.05 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 207 nm were prepared.

[0088] <Example 5: Preparation of functional particles> Only the difference from Example 1 will be described. Seed particles having an average particle size (D50) of 275 nm obtained in Production Example 5 were charged. 1.8 parts of trimethylolpropane trimethacrylate and 0.2 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 305 nm were prepared.

[0089] <Example 6: Preparation of functional particles> Only the difference from Example 1 will be described. Seed particles having an average particle size (D50) of 234 nm obtained in Production Example 6 were charged. 0.95 parts of trimethylolpropane trimethacrylate and 0.05 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 275 nm were prepared.

[0090] <Example 7: Preparation of functional particles> Only the difference from Example 1 will be described. Seed particles having an average particle size (D50) of 185 nm obtained in Production Example 7 were charged. 0.45 parts of cyclohexyl methacrylate and 0.05 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 224 nm were prepared.

[0091] <Example 8: Preparation of functional particles> Only the differences from Example 1 will be described. Seed particles having an average particle size (D50) of 164 nm obtained in Production Example 8 were charged. 0.95 parts of styrene and 0.05 parts of methacrylic acid were used. Functional particles having an average particle size (D50) of 195 nm were prepared.

[0092] <Comparative Example 1: Preparation of functional particles> (1) 2.0 parts of a functional substance (Tackifier A) and 20 parts of methyl methacrylate were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This was used to attempt to dissolve and liquefy the functional substance, but it had poor solubility in methyl methacrylate, and precipitated, making dissolution difficult.

[0093] <Comparative Example 2: Preparation of functional particles> (1) 2.0 parts of a functional substance (tackifier B) and 19 parts of styrene were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This resulted in a functional substance solution. After dissolution, 1.0 part of methacrylic acid, 40 parts of ion-exchanged water, and 0.5 parts of sodium dodecylbenzenesulfonate as an anionic surfactant were added, and the mixture was emulsified with a homogenizer to prepare an emulsion. No precipitation or sedimentation of Tackifier B was observed. (2) 40 parts of ion-exchanged water was weighed into a glass reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and an emulsion introduction tube, and the atmosphere in the vessel was replaced with nitrogen. Then, while stirring at 80°C, 0.2 parts of potassium persulfate was added, and the emulsion prepared in (1) was added dropwise over a period of 2 hours. Emulsion polymerization was attempted by further stirring and maturing at the same temperature for 3 hours, but the reaction was poor, and polymerization inhibition occurred when Tackifier B was dissolved, and resin particles could not be obtained successfully.

[0094] <Comparative Example 3: Preparation of functional particles> (1) 1.0 part of functional substance (polylactic acid A) and 19 parts of methyl methacrylate were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This resulted in a functional substance solution. After dissolution, 1.0 part of methacrylic acid, 40 parts of ion-exchanged water, and 0.5 parts of sodium dodecylbenzenesulfonate as an anionic surfactant were added, and the mixture was emulsified with a homogenizer to prepare an emulsion. No precipitation or sedimentation of polylactic acid A was observed. (2) 40 parts of ion-exchanged water was weighed into a glass reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and an emulsion inlet tube, and the atmosphere in the vessel was replaced with nitrogen. Then, while stirring at 80°C, 0.2 parts of potassium persulfate was added, and the emulsion prepared in (1) was added dropwise over a period of 2 hours. The mixture was further stirred and aged at the same temperature for 3 hours to complete the emulsion polymerization. Many aggregates were generated from the resulting emulsion. Most of these were precipitates of polylactic acid A.

[0095] <Comparative Example 4: Preparation of functional particles> (1) 2.0 parts of a functional substance (fluorescent dye A) and 20 parts of cyclohexyl methacrylate were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This was used to attempt to dissolve and liquefy the functional substance, but the solubility of the functional substance in cyclohexyl methacrylate was poor, and it precipitated, making dissolution difficult.

[0096] Comparative Example 5: Preparation of Functional Particles (1) 0.5 parts of a functional substance (fluorescent dye B) and 19 parts of styrene were added to a 100 ml glass container and stirred with a magnetic stirrer for 30 minutes. This resulted in a functional substance solution. After dissolution, 1.0 part of methacrylic acid, 40 parts of ion-exchanged water, and 0.5 parts of sodium dodecylbenzenesulfonate as an anionic surfactant were added, and the mixture was emulsified with a homogenizer to prepare an emulsion. No precipitation or sedimentation of fluorescent dye B was observed. (2) 40 parts of ion-exchanged water was weighed into a glass reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and an emulsion introduction tube, and the atmosphere in the vessel was replaced with nitrogen. Then, while stirring at 80°C, 0.2 parts of potassium persulfate was added, and the emulsion prepared in (1) was added dropwise over a period of 2 hours. Emulsion polymerization was attempted by further stirring and maturing at the same temperature for 3 hours, but the reaction was poor, and polymerization inhibition occurred when the fluorescent dye B was dissolved, and resin particles could not be successfully obtained.

[0097] <Test Method> Tests 1 and 2 were carried out using the seed particles of Production Examples 1 to 8. The following tests 1 to 3 were carried out using the functional particles of Examples 1 to 8 and Comparative Examples 1 to 5. In this way, the performance of the seed particles and the functional particles were evaluated.

[0098] (Test 1: Measurement of average particle size) The average particle size (D50) of the seed particles and the functional particles was measured using a particle size measuring device (Otsuka Electronics Co., Ltd., FPAR-1000).

[0099] (Test 2: Confirmation of particle stability) The stability of the prepared seed particles and functional particles was evaluated based on the presence or absence of separation and precipitation after standing at room temperature for 24 hours. [Evaluation Criteria] ○: Good stability (no separation or settling) ×: Poor stability (separation and settling)

[0100] (Test 3: Presence or absence of extra-particle precipitation of functional substances) The functional particle dispersion liquid was collected and dried at 23° C. for 1 hour, and then a scanning electron microscope (SEM) manufactured by JEOL Ltd. was used to confirm whether or not the functional substance was present outside the functional particles. [Evaluation Criteria] ○: No functional substance exists outside the functional particles ×: Functional substance is present outside the functional particles

[0101] <Test Results> The test results of Examples 1 to 8 and Comparative Examples 1 to 5 will be described with reference to Table 2 above. Fig. 1 shows an example of an SEM image of a seed particle according to one embodiment. Fig. 2 shows an example of an SEM image of a functional particle according to one embodiment.

[0102] Examples 1 to 8 show cases where each functional substance was successfully encapsulated in resin particles at a high concentration. In FIG. 1, there were no aggregates of functional substances other than the seed particles. Also, in FIG. 2, there were no aggregates of functional substances other than the functional particles. Thus, Examples 1 to 8 showed that there was no loss of functional substances throughout all the steps, including the pre-process (seed particle manufacturing process) and the post-process (functional particle manufacturing process). In other words, the relationship of calculated concentration of functional substance = actual concentration of functional substance in functional particles holds.

[0103] In Comparative Examples 1 to 5, each functional substance was prepared by conventional emulsion polymerization, but it was not possible to encapsulate the functional substance in the resin particles at a high concentration as shown in the Examples. Specifically, in Comparative Example 1, the functional substance (tackifier A) had low solubility in the monomer (methyl methacrylate), and it was difficult to dissolve it at a high concentration. In Comparative Example 2, the solubility could be improved by using styrene, which has a similar structure to the functional substance (tackifier B), as the monomer, but conventional emulsion polymerization caused polymerization inhibition, resulting in poor reaction and making it impossible to obtain functional particles. In Comparative Example 3, the functional substance (polylactic acid A) was able to be dissolved in the monomer (methyl methacrylate), but conventional emulsion polymerization caused agglomerates to form, and most of the functional substance precipitated outside the particles. Furthermore, in Comparative Example 4, the functional substance (fluorescent dye A) had low solubility in the monomer (cyclohexyl methacrylate), precipitated, and could not be dissolved. In Comparative Example 5, the functional substance (fluorescent dye B) could be dissolved in the monomer (styrene), but polymerization inhibition occurred during emulsion polymerization, resulting in poor reaction and making it impossible to obtain functional particles.

[0104] According to the test results, it was not possible to increase the concentration of the functional substance in the functional particles by the conventional methods shown in Comparative Examples 1 to 5. In addition, the storage stability of the functional particles of Comparative Examples 1 to 5 was very poor.

[0105] The main reason is that the solubility of the functional material in the monomer is low, and even if it can be dissolved, the conventional polymerization method causes polymerization inhibition, leading to poor reaction and making it impossible to obtain the desired functional particles. Therefore, in the comparative example, the concentration of the functional material in the functional particles cannot be increased.

[0106] As explained at the beginning of this specification, the condition for fully exerting the various functions of the functional material is to prevent the loss of the functional material in the functional particles and to increase the concentration of the functional material. However, as described above, the manufacturing methods of the functional particles of Comparative Examples 1 to 5 cannot satisfy this condition. On the other hand, the manufacturing method of the functional particles of the present invention can fully satisfy this condition.

[0107] As described above, the present invention has a remarkable effect of improving the storage stability of functional particles. In addition, the present invention can increase the concentration of functional material by preventing loss of the functional material during the manufacturing process of the functional particles. As a result, the present invention can provide high-quality functional particles that can fully exhibit various functions of the functional material.

[0108] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A functional particle having a core-shell structure, A core portion made of a functional material; A resin shell portion covering the core portion, The core portion is a nanoparticle, The resin contains, as constituent units relative to 100% by mass of all polymerizable monomers, 80 to 95% by mass of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, 80 to 95% by mass of an alicyclic alkyl group-containing unsaturated monomer, and 80 to 95% by mass of an aromatic group-containing unsaturated monomer, and 2 to 20% by mass of a carboxy group-containing ethylenically unsaturated monomer; The functional substance is any one of a tackifier, a polylactic acid, and a functional dye. Functional particles.

2. The average particle size of the core portion is 50 to 500 nm, The average particle size of the functional particles is 60 to 1000 nm, Here, the average particle diameter of the core portion and the average particle diameter of the functional particles are particle diameters (D50; median diameter) at cumulative 50% in a volume-based particle size distribution measured by a dynamic light scattering method. The functional particle according to claim 1 .

3. The functional material is contained in an amount of 5 to 95% by mass in 100% by mass of the functional particles. The functional particle according to claim 1 .

4. The resin contains, as a constituent unit, at least one of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, an alicyclic alkyl group-containing unsaturated monomer, an aromatic group-containing unsaturated monomer, and a crosslinkable monomer. The functional particle according to claim 1 .

5. The resin contains at least one of a carboxy group-containing ethylenically unsaturated monomer, a hydroxy group-containing ethylenically unsaturated monomer, an amino group-containing ethylenically unsaturated monomer, an amide group-containing ethylenically unsaturated monomer, and a sulfonic acid group-containing unsaturated monomer as a constituent unit. The functional particle according to claim 1 .

6. The carboxy group-containing ethylenically unsaturated monomer is methacrylic acid. The functional particle according to claim 1 .

7. The aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms is methyl methacrylate, The functional particle according to claim 1 .

8. The alicyclic alkyl group-containing unsaturated monomer is cyclohexyl methacrylate. The functional particle according to claim 1 .

9. The aromatic group-containing unsaturated monomer is styrene. The functional particle according to claim 1 .

10. A method for producing a functional particle having a core-shell structure, the method comprising the steps of: a core portion made of a functional material; and a shell portion made of a resin covering the core portion, the method comprising the steps of: a step of generating the core portion by stirring a mixture of the functional material dissolved in a solvent, a surfactant, and an aqueous dispersion medium; and generating a shell portion of the resin that covers the core portion by polymerizing a polymerizable monomer in the presence of the core portion, The solvent includes an organic solvent, The organic solvent includes at least one of methylene chloride, ethylene dichloride, chloroform, carbon tetrachloride, ethyl acetate, methyl acetate, cyclohexane, cyclopentane, tetrahydrofuran, toluene, hexane, and heptane; The resin contains, as constituent units relative to 100% by mass of all polymerizable monomers, 80 to 95% by mass of an aliphatic alkyl group-containing unsaturated monomer having a linear or branched alkyl group having 1 to 18 carbon atoms, 80 to 95% by mass of an alicyclic alkyl group-containing unsaturated monomer, and 80 to 95% by mass of an aromatic group-containing unsaturated monomer, and 2 to 20% by mass of a carboxy group-containing ethylenically unsaturated monomer; The functional substance is any one of a tackifier, a polylactic acid, and a functional dye. A method for producing functional particles.

11. A step of removing the solvent after the step of generating the core portion is included. The method of claim 10.

12. After the step of generating the shell portion, a step of extracting functional particles having a predetermined average particle size from the functional particles by using centrifugation is included. The method of claim 10.

13. The resin shell is produced using seeded emulsion polymerization. The method of claim 10.

14. The surfactant is an anionic surfactant. The method of any one of claims 10 to 13.

Images