JP2011089018A - Hydrophobic core-shell silica particle, hollow silica particle and process for producing these particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide core-shell silica particles and hollow silica particles which can be added to an organic solvent and a non-water soluble medium such as a resin at a high concentration and does not cause turbidity, whitening and the like in the system after being added to the non-water soluble medium or does not cause the gelling of the system after being added, and furthermore a process for producing the core-shell silica particles and the hollow silica particles. <P>SOLUTION: The core-shell silica particles included: a shell layer containing silica represented by the composition formula of SiO<SB>2</SB>as component (A), a modified silica represented by the composition formula of formula (2): R'<SB>2</SB>SiO (wherein R' is a hydrocarbon group having a total of 1-24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth)acrylic group, and an epoxy group or the like) or the composition formula of formula (1): RSiO<SB>3/2</SB>(wherein R is a hydrocarbon group having a total of 1-24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth)acrylic group, and an epoxy group or the like) and the formula (2) as component (B), and a modified silica represented by the composition formula of formula (3): R"<SB>3</SB>SiO<SB>1/2</SB>(wherein R" is a hydrocarbon group having a total of 1-24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth)acrylic group, and an epoxy group or the like) as component (C); and a core composed of a resin obtained by emulsion polymerization. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a core-shell silica particle, hollow silica particle that can be added at a high concentration to a water-insoluble medium such as an organic solvent or resin, and does not cause turbidity or whitening in the system after addition to the water-insoluble medium, and these It relates to a manufacturing method.

  Silica fine particles typified by colloidal silica are used in various fields such as electronic materials, civil engineering and construction materials, paper industry, paints, foods, etc. These silica fine particles are added to oil, organic solvents or resins. There are many uses. If water-soluble silica fine particles are added to such a water-insoluble medium, generally, problems such as aggregation and separation occur, so that they cannot be used. Therefore, it is carried out by replacing the silanol group (hydroxyl group) on the surface of the silica fine particle with a hydrophobic group such as an alkyl group, and adding the silica fine particle to the water-insoluble medium by making it hydrophobic (for example, (See Patent Documents 1 and 2).

  However, since the silica fine particles as in Patent Documents 1 and 2 have a large specific gravity, the stability in a water-insoluble medium is poor. Accordingly, silica fine particles (see, for example, Patent Document 3 and Japanese Patent Application No. 2009-119887 filed by the present applicant) coated with a resin having a small specific gravity or the like, and hollow silica (for example, patents) Reference 4) is known. Reducing the specific gravity of the silica fine particles greatly contributes to improving the stability of the silica fine particles in the water-insoluble medium.

  However, even with highly stable silica fine particles with a low specific gravity, the fine particle surface modification methods known so far cannot sufficiently hydrophobize silica fine particles, and the high concentration in a non-aqueous medium. There was a problem that it could not be added, and there was a problem that the system after the addition became cloudy, whitened, or gelled. These problems also occur when the inside of the fine particles is hollow silica having a cavity. Accordingly, the market demanded silica fine particles and hollow silica that can be added to a water-insoluble medium at a high concentration and that do not cause turbidity or whitening after the addition.

JP-A-10-059708 JP 2002-162533 A JP 2009-024077 A JP 2008-274261 A

  Therefore, the problem to be solved by the present invention is that it can be added to a water-insoluble medium such as an organic solvent or a resin at a high concentration and does not cause turbidity or whitening in the system after addition to the water-insoluble medium, or An object of the present invention is to provide core-shell silica particles and hollow silica particles in which the system after addition does not gel, and to provide a method for producing the core-shell silica particles and the hollow silica particles.

Therefore, the present inventors diligently studied and found silica fine particles that can be stably dispersed over a long period of time in a water-insoluble medium, leading to the present invention. That is, the present invention is the silica represented by the composition formula of SiO ₂ as the component (A), the composition formula of the general formula (2) as the component (B), or the composition formula of the general formula (1) and the general formula (2). And a shell layer containing a modified silica represented by the composition formula of the general formula (3) as a component (C) and a core made of a resin obtained by emulsion polymerization. Silica particles.
RSiO _3/2 (1)
(In the formula, R is a hydrocarbon group having 1 to 24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 to 1 carbon atoms). Represents 24 halogenated alkyl groups.)
R ′ ₂ SiO (2)
(In the formula, R ′ is a hydrocarbon group having 1 to 24 carbon atoms in total which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)
R " ₃ SiO _1/2 (3)
(In the formula, R ″ represents a hydrocarbon group having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)

  The effect of the present invention is that it can be added to a water-insoluble medium such as an organic solvent or a resin at a high concentration, and the system after addition to the water-insoluble medium does not cause turbidity or whitening, or the system after the addition is a gel. The present invention provides a core-shell silica particle and a hollow silica particle that are not converted, and further provides a method for producing the core-shell silica particle and the hollow silica particle.

The core-shell silica particles of the present invention are silica represented by the composition formula of SiO ₂ as the component (A), the composition formula of the general formula (2) as the component (B), or the general formula (1) and the general formula (2). A modified silica represented by a composition formula, and a shell layer containing a modified silica represented by the composition formula of the general formula (3) as a component (C), and a core made of a resin obtained by emulsion polymerization, Core-shell silica particles.
RSiO _3/2 (1)
(In the formula, R is a hydrocarbon group having 1 to 24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 to 1 carbon atoms). Represents 24 halogenated alkyl groups.)
R ′ ₂ SiO (2)
(In the formula, R ′ is a hydrocarbon group having 1 to 24 carbon atoms in total which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)
R " ₃ SiO _1/2 (3)
(In the formula, R ″ represents a hydrocarbon group having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)

  The resin that can be used in the present invention may be any resin produced by a known method by emulsion polymerization. For example, ethylene, propylene, butadiene, isobutylene, acrylonitrile, isoprene, styrene, alkyl vinyl ether, (meth) acrylic acid ester, Examples include those obtained by emulsifying monomers such as maleic acid, vinyl acetate, vinylidene chloride, allylamine, vinyl pyridine, and cyanoacrylate with water and a surfactant (emulsifier) and polymerizing with a polymerization initiator. In addition, an emulsion of a urethane resin obtained by reacting a polyol such as polyether polyol, polyester polyol or polycarbonate polyol with an isocyanate compound, or an emulsion of an epoxy resin obtained by reacting an epoxy compound with the polyol or amine compound, Alternatively, it may be an emulsion of a resin in which one or more of the monomer, polyol, isocyanate and epoxy compound are reacted by emulsion polymerization (including those containing a reactive group). The emulsion resin has a resin size and particle size distribution determined by conditions such as monomer type, monomer concentration, reaction temperature, emulsifier concentration, initiator concentration, etc. What is necessary is just to adjust these conditions suitably and to perform emulsion polymerization.

  Specific emulsion resins include, for example, urethane emulsions, acrylate emulsions, styrene emulsions, vinyl acetate emulsions, SBR (styrene / butadiene) emulsions, ABS (acrylonitrile / butadiene / styrene) emulsions, and BR (butadiene) emulsions. , IR (isoprene) emulsion, NBR (acrylonitrile / butadiene) emulsion, or an emulsion resin obtained from a mixture thereof.

  Examples of the urethane emulsion include polyether polyol, polyester polyol, and polycarbonate polyol.

  Examples of the acrylate emulsion include (meth) acrylic acid (ester) alone, (meth) acrylic acid (ester) / styrene, (meth) acrylic acid (ester) / vinyl acetate, (meth) acrylic acid (ester) / Acrylonitrile, (meth) acrylic acid (ester) / butadiene, (meth) acrylic acid (ester) / vinylidene chloride, (meth) acrylic acid (ester) / allylamine, (meth) acrylic acid (ester) / vinylpyridine, (meth ) Acrylic acid (ester) / alkylolamide, (meth) acrylic acid (ester) / N, N-dimethylaminoethyl ester, (meth) acrylic acid (ester) / N, N-diethylaminoethyl vinyl ether, cyclohexyl methacrylate, Epoxy-modified, urethane-modified, etc. It is below.

  Examples of the styrene emulsion include styrene alone, styrene / acrylonitrile, styrene / butadiene, styrene / fumaronitrile, styrene / maleonitrile, styrene / cyanoacrylate, styrene / phenylvinyl acetate, styrene / chloromethylstyrene, styrene / Examples include dichlorostyrene, styrene / vinyl carbazole, styrene / N, N-diphenylacrylamide, styrene / methyl styrene, acrylonitrile / butadiene / styrene, styrene / acrylonitrile / methyl styrene, styrene / acrylonitrile / vinyl carbazole, styrene / maleic acid, and the like. .

  Examples of vinyl acetate emulsions include vinyl acetate alone, vinyl acetate / styrene, vinyl acetate / vinyl chloride, vinyl acetate / acrylonitrile, vinyl acetate / maleic acid (ester), vinyl acetate / fumaric acid (ester), vinyl acetate / Polymers such as ethylene, vinyl acetate / propylene, vinyl acetate / isobutylene, vinyl acetate / vinylidene chloride, vinyl acetate / cyclopentadiene, vinyl acetate / crotonic acid, vinyl acetate / acrolein, vinyl acetate / alkyl vinyl ether and the like can be mentioned.

  Among these emulsions, a resin obtained from an acrylate-based emulsion and a styrene-based emulsion is preferable because the particle diameter can be easily controlled. When producing hollow silica, which will be described later, the elution of the resin is easy. A resin obtained from a system emulsion is more preferred. The particle size of these resins may be determined as necessary, but the particle size is preferably 10 to 350 nm. A particle size in this range can be easily produced by emulsion polymerization.

  Any emulsifier that can be used in the above emulsion polymerization can be used as long as it is a known surfactant, and examples thereof include an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. .

  Examples of the anionic surfactant include higher fatty acid salts, higher alcohol sulfate esters, sulfurized olefin salts, higher alkyl sulfonates, α-olefin sulfonates, sulfated fatty acid salts, sulfonated fatty acid salts, and phosphate ester salts. , Fatty acid ester sulfate ester salt, glyceride sulfate ester salt, fatty acid ester sulfonate salt, α-sulfo fatty acid methyl ester salt, polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene alkyl phenyl ether sulfate ester salt, polyoxyalkylene Alkyl ether carboxylate, acylated peptide, sulfate ester salt of fatty acid alkanolamide or its alkylene oxide adduct, sulfosuccinate ester, alkylbenzene sulfonate, alkyl naphthalene sulfonate Salt, alkylbenzimidazole sulfonate, polyoxyalkylene sulfosuccinate, N-acyl-N-methyltaurine salt, N-acyl glutamic acid or salt thereof, acyloxyethane sulfonate, alkoxyethane sulfonate, N-acyl -Β-alanine or salt thereof, N-acyl-N-carboxyethyltaurine or salt thereof, N-acyl-N-carboxymethylglycine or salt thereof, acyl lactate, N-acyl sarcosine salt, and alkyl or alkenylaminocarboxy Examples thereof include methyl sulfate.

  Nonionic surfactants include, for example, polyoxyalkylene alkyl ether, polyoxyalkylene alkenyl ether, polyoxyethylene polyoxypropylene alkyl ether (addition form of ethylene oxide and propylene oxide may be random or block) .), Polyethylene glycol propylene oxide adduct, polypropylene glycol ethylene oxide adduct, glycerin fatty acid ester or ethylene oxide adduct thereof, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, alkyl polyglucoside, fatty acid monoethanolamide or ethylene oxide thereof Adduct, fatty acid-N-methylmonoethanolamide or its ethylene oxide adduct, fatty acid dietano Ruamido or an ethylene oxide adduct, a sucrose fatty acid ester, alkyl (poly) glycerol ether, polyglycerol fatty acid esters, polyethylene glycol fatty acid esters, fatty acid methyl ester ethoxylates, N- long chain alkyl dimethyl amine oxides, and the like.

Examples of the cationic surfactant include alkyl (alkenyl) trimethyl ammonium salt, dialkyl (alkenyl) dimethyl ammonium salt, alkyl (alkenyl) quaternary ammonium salt, mono- or dialkyl (alkenyl) containing ether group, ester group or amide group. ) Quaternary ammonium salt, alkyl (alkenyl) pyridinium salt, alkyl (alkenyl) dimethylbenzyl ammonium salt, alkyl (alkenyl) isoquinolinium salt, dialkyl (alkenyl) morphonium salt, polyoxyethylene alkyl (alkenyl) amine, alkyl (alkenyl) amine Examples thereof include salts, polyamine fatty acid derivatives, amyl alcohol fatty acid derivatives, benzalkonium chloride, and benzethonium chloride.
Examples of the amphoteric surfactant include carboxybetaine, sulfobetaine, phosphobetaine, amide amino acid, imidazolinium betaine surfactant and the like.

  In addition, a reactive surfactant having a double bond in the molecule can also be used. Examples of such reactive surfactant include, for example, JP-A-58-203960 and JP-A-61-222530. JP-A 63-023725, JP-A 63-091130, JP-A 04-256429, JP-A 06-239908, JP-A 08-041113, JP-A 2002-301353. Etc. are mentioned. Among these surfactants, cationic surfactants are preferred because the silane compound used to form the shell layer is likely to adhere to the resin surface.

  When producing an emulsion, the above-mentioned emulsifier may be used alone or in combination of two or more, and can be arbitrarily used within the range of the usual use amount. What is necessary is just to add and use 0.5 mass%, More preferably 0.2-10 mass%, More preferably 0.5-8 mass%.

  When producing a resin that can be used in the present invention, a known additive, for example, a phenol-based, phosphorus-based, or sulfur-based antioxidant; an ultraviolet absorber; a film forming aid; a chain transfer agent; Antiseptic / antibacterial agent; insecticidal fungicide; solvent; plasticizer; dispersant; thickener; defoamer; deodorant; fragrance; Among these, it is preferable to use a chain transfer agent.

  Examples of the chain transfer agent include mercaptoethanol, thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, 2-mercaptoethanesulfonic acid, butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecane Thiol compounds such as thiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, octyl 3-mercaptopropionate; secondary alcohols such as isopropyl alcohol; phosphorous acid, hypophosphorous acid and salts thereof (sodium hypophosphite) , Potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionic acid, metabisulfite and its salts (sodium sulfite, sodium bisulfite, sodium dithionite, sodium metabisulfite) Etc.) lower thio oxides, and the like and may be a known chain transfer agent salts thereof. The reason for the preference will be described later.

Next, the silica compound of the shell layer will be described. It is one component (A) component of the silica compound is a silica represented by a composition formula of SiO _2. In order to generate the component (A), it is obtained by reacting a specific silane compound (hereinafter referred to as (a-1) compound). As such (a-1) compound, for example, sodium silicate And silicates such as potassium silicate; chlorosilanes such as monochlorosilane, dichlorosilane, and trichlorosilane; and tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Among these, silicates and chlorosilanes preferably contain tetraalkoxysilanes because they contain alkali metal atoms and chlorine atoms, and impurities are generated and the reaction is difficult to control. Among tetraalkoxysilanes, tetramethoxysilane and tetraethoxysilane are preferable, and tetramethoxysilane is more preferable because of good control of the reaction.

The component (B), which is one of the components of the silica compound, is composed of modified silica represented by the composition formula of the following general formula (2), or the composition formulas of the following general formula (1) and general formula (2). Modified silica.
RSiO _3/2 (1)
(In the formula, R is a hydrocarbon group having 1 to 24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 to 1 carbon atoms). Represents 24 halogenated alkyl groups.)
R ′ ₂ SiO (2)
(In the formula, R ′ is a hydrocarbon group having 1 to 24 carbon atoms in total which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)

  R and R ′ in the general formula (1) and the general formula (2) may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group. It is a -24 hydrocarbon group or a C1-C24 halogenated alkyl group.

  Examples of the hydrocarbon group having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group include, for example, a methyl group, an ethyl group, and a propyl group Group, isopropyl group, butyl group, isobutyl group, tertiary butyl group, pentyl group, isopentyl group, neopentyl group, tertiary pentyl group, hexyl group, isohexyl group, heptyl group, isoheptyl group, octyl group, 2-ethylhexyl group, Nonyl, isononyl, decyl, isodecyl, undecyl, isoundecyl, dodecyl, isododecyl, tridecyl, isotridecyl, tetradecyl, isotetradecyl, hexadecyl, isohexadecyl, octadecyl, iso Octadecyl group, 2-butyloctyl group, 2 Alkyl groups such as butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldecyl, 2-hexyloctadecyl; vinyl, allyl, propenyl, isopropenyl, Alkenyl groups such as butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl; phenyl, toluyl, Xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl The Tylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, octadecylphenyl group, styrenated phenyl group, p-cumylphenyl group, phenylphenyl group, benzylphenyl group, α-naphthyl group, β-naphthyl Aromatic-containing hydrocarbon groups such as amino groups; aminoethyl groups, aminopropyl groups, aminobutyl groups, aminopentyl groups, aminohexyl groups, 2-acryloxyethyl groups, 2-methacryloxyethyl groups, 3-acryloxypropyl groups Amino groups such as 3-methacryloxypropyl group, 3-mercaptopropyl group, 3-mercaptopropyl group, 3-glycidoxypropyl group, 3-glycidoxypropyl group, mercapto group, (meth) acrylic group and epoxy Hydrocarbons substituted with any group selected from the group Group, and the like. In addition, the total carbon number of an alkenyl group is 2-24, and the total carbon number of an aromatic containing hydrocarbon group is 6-24.

  Examples of the halogenated alkyl group having 1 to 24 carbon atoms include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, perfluorooctyl group, Perfluorodecyl group, perfluoro-3-methylbutyl group, perfluoro-5-methylhexyl group, perfluoro-7-methyloctyl group, 2- (perfluorobutyl) ethyl group, 2- (perfluorohexyl) ethyl group 2- (perfluorooctyl) ethyl group, 2- (perfluorodecyl) ethyl group, 1H, 1H, 5H-octafluoropentyl group, 1H, 1H, 7H-dodecafluoroheptyl group, 1H, 1H, 9H-hexa Decafluorononyl group, 3- (perfluorohexyl) propyl group 3- (perfluorooctyl) propyl group, 2- (perfluoro-3-methylbutyl) ethyl group, 2- (perfluoro-5-methylhexyl) ethyl group, 2- (perfluoro-7-methyloctyl) ethyl group , 2- (perfluoro-9-methyldecyl) ethyl group and the like. R and R ′ are the same as the groups derived from the silica compounds (b-1) and (b-2) described below, but preferred R and R ′ are the preferred (b-1) compounds and (b— 2) Same as the group derived from the compound.

  In order to produce the modified silica compound represented by the composition formula of the general formula (1), it is obtained by reacting a specific silane compound, but as such a silane compound (hereinafter referred to as (b-1) compound). For example, monomethyltrimethoxysilane, monomethyltriethoxysilane, monoethyltrimethoxysilane, monopropyltrimethoxysilane, monobutyltrimethoxysilane, monopentyltrimethoxysilane, monohexyltrimethoxysilane, monooctyltrimethoxysilane, Monoalkyltrialkoxysilanes such as monodecyltrimethoxysilane, monododecyltrimethoxysilane, monotetradecyltrimethoxysilane, monohexadecyltrimethoxysilane, monooctadecyltrimethoxysilane; Halogenated alkyl group-containing trialkoxysilanes such as fluorine-modified products of orchids; aromatics such as monophenyltrimethoxysilane, monophenyltriethoxysilane, mono (alkylphenyl) trimethoxysilane, mono (dialkylphenyl) trimethoxysilane Group-containing trialkoxysilanes; monoalkenyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane; aminoethyltrimethoxysilane, aminopropyltrimethoxysilane, aminobutyltri Amino group-containing trialkoxysilanes such as methoxysilane, aminoethyltriethoxysilane, aminopropyltriethoxysilane, and aminobutyltriethoxysilane; 3-methacryloxypropoxy (Meth) acrylic group-containing trialkoxysilanes such as trimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane; 3-mercaptopropyltrimethoxysilane Mercapto group-containing trialkoxysilanes such as 3-mercaptopropyltriethoxysilane; Epoxy group-containing trialkoxysilanes such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane; Monomethyltrichlorosilane Monoethyltrichlorosilane, monopropyltrichlorosilane, monobutyltrichlorosilane, monopentyltrichlorosilane, monohexyltrichlorosilane, monooctyltrichlorosilane, monode Monoalkyltrichlorosilanes such as siltrichlorosilane, monododecyltrichlorosilane, monotetradecyltrichlorosilane, monohexadecyltrichlorosilane, monooctadecyltrichlorosilane; halogenated alkyl group-containing tris such as fluorine-modified products of the monoalkylchlorosilanes Aromatic-containing trichlorosilanes such as monophenyltrichlorosilane, mono (alkylphenyl) trichlorosilane, mono (dialkylphenyl) trichlorosilane; monoalkenyltrichlorosilanes such as vinyltrichlorosilane and allyltrichlorosilane; aminoethyltri Amino group-containing trichlorosilanes such as chlorosilane, aminopropyltrichlorosilane, and aminobutyltrichlorosilane; 3-methacryloxypropylto (Meth) acrylic group-containing trichlorosilanes such as chlorosilane and 3-acryloxypropyltrichlorosilane; mercapto group-containing trichlorosilanes such as 3-mercaptopropyltrichlorosilane; and epoxy group-containing tris such as 3-glycidoxypropyltrichlorosilane Examples include chlorosilanes.

  Among these, since chlorosilanes contain a chlorine atom, impurities derived from the chlorine atom are generated and it is difficult to control the reaction, so it is preferable to use alkoxysilanes. In addition, when it is preferable that the compound (b-1) imparts performance other than hydrophobicity such as a reactive group to the particle, a halogenated alkyl group-containing trialkoxysilane, a monoalkenyltrialkoxysilane, an amino group More preferable are trialkoxysilanes containing, trialkoxysilanes containing (meth) acrylic groups, trialkoxysilanes containing mercapto groups, trialkoxysilanes containing epoxy groups.

  In order to produce the modified silica compound represented by the composition formula of the general formula (2), it is obtained by reacting a specific silane compound. As such a silane compound (hereinafter referred to as (b-2) compound), Dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, dibutyldimethoxysilane, dipentyldimethoxysilane, dihexyldimethoxysilane, dioctyldimethoxysilane, didecyldimethoxysilane, didodecyldimethoxysilane, ditetradecyldimethoxysilane Silane, dihexadecyldimethoxysilane, dioctadecyldimethoxysilane, methylethyldimethoxysilane, methylpropyldimethoxysilane, methylbutyldimethoxysilane, methylhexyldimethoxysilane, Tyloctyldimethoxysilane, methyldecyldimethoxysilane, methyldodecyldimethoxysilane, methyloctadecyldimethoxysilane, ethylpropyldimethoxysilane, ethylbutyldimethoxysilane, ethylhexyldimethoxysilane, ethyloctyldimethoxysilane, ethyldecyldimethoxysilane, ethyldodecyldimethoxysilane Dialkyldialkoxysilanes such as ethyl octadecyldimethoxysilane; halogenated alkyl group-containing dialkoxysilanes such as fluorine-modified products of the dialkylalkoxysilanes; diphenyldimethoxysilane, diphenyldiethoxysilane, di (alkylphenyl) dimethoxysilane , Di (dialkylphenyl) dimethoxysilane, methylphenyldimethoxysilane, ethylpheny Aromatic dialkoxysilanes such as dimethoxysilane and methylalkylphenyldimethoxysilane; divinyldimethoxysilane, divinyldiethoxysilane, diallyldimethoxysilane, diallyldiethoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, methylallyldimethoxy Alkenyl group-containing dialkoxysilanes such as silane; aminopropylmethyldimethoxysilane, aminopropylmethyldiethoxysilane, aminopropylethyldimethoxysilane, aminopropylpropyldimethoxysilane, aminopropylbutyldimethoxysilane, aminobutylbutyldimethoxysilane, di ( Amino group-containing dialkoxysilanes such as aminopropyl) dimethoxylane and aminoethylaminopropyldimethoxylane 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylethyldimethoxysilane, 3-methacryloxypropylpropyldimethoxysilane, 3-methacryloxypropylbutyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acrylic (Meth) acrylic group-containing dialkoxysilanes such as loxypropylmethyldimethoxysilane and 3-acryloxypropylmethyldiethoxysilane; 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylethyldimethoxysilane, 3-mercaptopropylpropyldimethoxy Mercapto group-containing dialkoxysilanes such as silane, 3-mercaptopropylbutyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethyldimethoxysilane, 3-glycidoxypropylpropyldimethoxysilane, 3-glycidoxypropylbutyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane Epoxy group-containing dialkoxysilanes such as dimethyldichlorosilane, diethyldichlorosilane, dipropyldichlorosilane, dibutyldichlorosilane, dipentyldichlorosilane, dihexyldichlorosilane, dioctyldichlorosilane, didecyldichlorosilane, didodecyldichlorosilane, dido Tetradecyldichlorosilane, dihexadecyldichlorosilane, dioctadecyldichlorosilane, methylethyldichlorosilane, methylpropyldichlorosilane, methylbuty Dichlorosilane, methylhexyldichlorosilane, methyloctyldichlorosilane, methyldecyldichlorosilane, methyldodecyldichlorosilane, methyloctadecyldichlorosilane, ethylpropyldichlorosilane, ethylbutyldichlorosilane, ethylhexyldichlorosilane, ethyloctyldichlorosilane, Dialkyldichlorosilanes such as ethyldecyldichlorosilane, ethyldodecyldichlorosilane, ethyloctadecyldichlorosilane; halogenated alkyl group-containing dichlorosilanes such as fluorine-modified products of the dialkyldichlorosilanes; diphenyldichlorosilane, di (alkylphenyl) Dichlorosilane, di (dialkylphenyl) dichlorosilane, methylphenyldichlorosilane, ethylphenyldichlorosilane, methyl Aromatic-containing dichlorosilanes such as dialkylphenyldichlorosilane; Divinyldichlorosilane, diallyldichlorosilane, methylvinyldichlorosilane, ethylvinyldiethoxysilane, methylallyldichlorosilane and other alkenyl group-containing dichlorosilanes; aminopropylmethyldi Amino group-containing dichlorosilanes such as chlorosilane, aminopropylethyldichlorosilane, aminopropylpropyldichlorosilane, aminopropylbutyldichlorosilane, aminobutylbutyldichlorosilane, di (aminopropyl) dichlorosilane, aminoethylaminopropyldichlorosilane; 3 -Methacryloxypropylmethyldichlorosilane, 3-methacryloxypropylethyldichlorosilane, 3-methacryloxypropylpropyldichlorosilane (Meth) acrylic group-containing dichlorosilanes such as 3-methacryloxypropylbutyldichlorosilane, 3-acryloxypropylmethyldichlorosilane; 3-mercaptopropylmethyldichlorosilane, 3-mercaptopropylethyldichlorosilane, 3-mercaptopropyl Mercapto group-containing dichlorosilanes such as propyldichlorosilane and 3-mercaptopropylbutyldichlorosilane; 3-glycidoxypropylmethyldichlorosilane, 3-glycidoxypropylethyldichlorosilane, 3-glycidoxypropylpropyldichlorosilane, Epoxy group-containing dichlorosilanes such as 3-glycidoxypropylbutyldichlorosilane are exemplified.

  Among these, since chlorosilanes contain chlorine atoms, it is preferable to use alkoxysilanes because impurities derived from chlorine atoms are generated and reaction control is difficult, and dialkyl dialkoxysilanes are preferred. Dialkyldimethoxysilanes are more preferable, and dimethyldimethoxysilane is most preferable because the reaction is more easily controlled. The reason why a group having a low molecular weight such as a methyl group is preferable is that there is little steric hindrance during the reaction, and a detailed explanation thereof will be described later.

Component (C), which is one of the components of the silica compound, is a modified silica represented by the composition formula of the following general formula (3).
R " ₃ SiO _1/2 (3)
(In the formula, R ″ represents a hydrocarbon group having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)

  Examples of R ″ in the general formula (3) include the groups listed above as R in the general formula (1). R ″ is the same as the group derived from the silica compound (c-1) described below. However, preferred R ″ is a group derived from the preferred compound (c-1).

  In order to produce the modified silica compound represented by the composition formula of the general formula (3), it is obtained by reacting a specific silane compound. Such a silane compound (hereinafter referred to as (c-1) compound). For example, trimethylmonomethoxysilane, trimethylmonoethoxysilane, triethylmonomethoxysilane, tripropylmonomethoxysilane, tributylmonomethoxysilane, tripentylmonomethoxysilane, trihexylmonomethoxysilane, trioctylmonomethoxysilane, Decylmonomethoxysilane, tridodecylmonomethoxysilane, tritetradecylmonomethoxysilane, trihexadecylmonomethoxysilane, trioctadecylmonomethoxysilane, dimethylethyltrimethoxysilane, methyldiethyltrimethoxysilane Trialkyl monoalkoxysilanes such as chlorosilanes; halogenated alkyl group-containing monoalkoxysilanes such as fluorine-modified products of the above trialkylalkoxysilanes; triphenylmonomethoxysilane, triphenylmonoethoxysilane, tri (alkylphenyl) mono Methoxysilane, tri (dialkylphenyl) monomethoxysilane, diphenylmethylmonomethoxysilane, dimethylphenylmonomethoxysilane, di (alkylphenyl) methylmonomethoxysilane, dimethyl (alkylphenyl) monomethoxysilane, di (dialkylphenyl) methylmono Aromatic-containing monoalkoxysilanes such as methoxysilane and dimethyl (dialkylphenyl) monomethoxysilane; vinyldimethylmonomethoxysilane, vinyldiethylmonomethoxysila Alkenyl group-containing monoalkoxysilanes such as vinyldimethylmonoethoxysilane, allyldimethylmonomethoxysilane, allyldiethylmonomethoxysilane, allyldimethylmonoethoxysilane, divinylmethylmonomethoxysilane, divinylethylmonomethoxysilane, diallylmethylmonomethoxysilane Aminopropyldimethylmonomethoxysilane, aminopropyldimethylmonoethoxysilane, aminopropyldiethylmonomethoxysilane, aminopropyldipropylmonomethoxysilane, aminopropyldibutylmonomethoxysilane, aminobutyldibutylmonomethoxysilane, di (aminopropyl) Amino group-containing monoalkoxysilanes such as methylmonomethoxylane and aminoethylaminopropylmethylmonomethoxylane; 3-methacryloxypropyldimethylmonomethoxysilane, 3-methacryloxypropyldiethylmonomethoxysilane, 3-methacryloxypropyldipropylmonomethoxysilane, 3-methacryloxypropyldibutylmonomethoxysilane, 3-methacryloxypropyldimethylmonoethoxysilane (Meth) acrylic group-containing monoalkoxysilanes such as 3-acryloxypropyldimethylmonomethoxysilane, 3-acryloxypropyldimethylmonoethoxysilane; 3-mercaptopropyldimethylmonomethoxysilane, 3-mercaptopropyldiethylmonomethoxysilane 3-mercaptopropyldipropylmonomethoxysilane, 3-mercaptopropyldibutylmonomethoxysilane, 3-mercaptopropyldimethylmonoethoxy Mercapto group-containing monoalkoxysilanes such as silane; 3-glycidoxypropyldimethylmonomethoxysilane, 3-glycidoxypropyldiethylmonomethoxysilane, 3-glycidoxypropyldipropylmonomethoxysilane, 3-glycidoxy Epoxy group-containing monoalkoxysilanes such as propyldibutylmonomethoxysilane and 3-glycidoxypropyldimethylmonoethoxysilane; trimethylmonochlorosilane, triethylmonochlorosilane, tripropylmonochlorosilane, tributylmonochlorosilane, tripentylmonochlorosilane, trihexyl Monochlorosilane, trioctylmonochlorosilane, tridecylmonochlorosilane, tridodecylmonochlorosilane, tritetradecylmonochlorosilane, trihexadecyl Trialkylmonochlorosilanes such as nochlorosilane, trioctadecylmonochlorosilane, dimethylethyltrimethoxysilane, and methyldiethyltrimethoxysilane; halogenated alkyl group-containing monochlorosilanes such as fluorine-modified products of the trialkylmonochlorosilanes; triphenyl Monochlorosilane, tri (alkylphenyl) monochlorosilane, tri (dialkylphenyl) monochlorosilane, diphenylmethylmonochlorosilane, dimethylphenylmonochlorosilane, di (alkylphenyl) methylmonochlorosilane, dimethyl (alkylphenyl) monochlorosilane, di (dialkylphenyl) ) Aromatic monochlorosilanes such as methylmonochlorosilane and dimethyl (dialkylphenyl) monochlorosilane; vinyldimethyl Monochlorosilanes containing alkenyl groups such as monochlorosilane, vinyldiethylmonochlorosilane, allyldimethylmonochlorosilane, allyldiethylmonochlorosilane, divinylmethylmonochlorosilane, divinylethylmonochlorosilane, diallylmethylmonochlorosilane; aminopropyldimethylmonochlorosilane, aminopropyldiethyl Amino group-containing monochlorosilanes such as monochlorosilane, aminopropyldipropylmonochlorosilane, aminopropyldibutylmonochlorosilane, aminobutyldibutylmonochlorosilane, di (aminopropyl) methylmonochlorolane, aminoethylaminopropylmethylmonochlorolane; Loxypropyldimethylmonochlorosilane, 3-methacryloxypropyldiethylmonochloro (Meth) acrylic group-containing monochlorosilanes such as silane, 3-methacryloxypropyldipropylmonochlorosilane, 3-methacryloxypropyldibutylmonochlorosilane, 3-acryloxypropyldimethylmonochlorosilane; 3-mercaptopropyldimethylmonochlorosilane, 3 -Mercapto group-containing monochlorosilanes such as mercaptopropyldiethylmonochlorosilane, 3-mercaptopropyldipropylmonochlorosilane, 3-mercaptopropyldibutylmonochlorosilane; 3-glycidoxypropyldimethylmonochlorosilane, 3-glycidoxypropyldiethylmono Epoxy group-containing compounds such as chlorosilane, 3-glycidoxypropyldipropylmonochlorosilane, and 3-glycidoxypropyldibutylmonochlorosilane Roshiran acids and the like.

  Among these, since chlorosilanes contain chlorine atoms, it is preferable to use alkoxysilanes because impurities derived from chlorine atoms are generated and reaction control is difficult. Silanes are more preferable, and trialkylmonomethoxysilanes are more preferable, and trimethylmonomethoxysilane is most preferable because of easy control of the reaction. The reason why a group having a low molecular weight such as a methyl group is preferable is that there is little steric hindrance during the reaction, and a detailed explanation thereof will be described later.

  Next, the shell layer of the core-shell silica particles of the present invention will be described in more detail. There are two factors that determine the water-solubility and water-insolubility of silica particles: the proportion of silanol groups present on the surface of the particles and the type and proportion of hydrophobic groups present on the surface of the particles. If the particle diameter and particle size distribution are the same, the degree of hydrophilicity and hydrophobicity of the whole particle is determined by these two factors. Silica particles are dotted with many silanol groups on the surface, so they are highly hydrophilic and generally water-soluble. However, when silanol groups are reacted with alkyl-modified silica, the silanol groups are replaced with alkyl groups. Therefore, it is thought that the whole particle becomes hydrophobic.

  However, the (b-1) compound such as monoalkyltrimethoxysilane has three groups (methoxy groups) that react with silanol groups. All of these should react with silanol groups, but the silanol groups on the surface of the silica particles are interspersed, and each of them is immobilized, so that all three methoxy groups hardly react. In many cases, one methoxy group reacts with a silanol group, and all remaining methoxy groups become hydroxyl groups. Therefore, when an alkyl group or the like derived from the (b-1) compound is added to the silica particles, the number of hydroxyl groups increases, and sufficient hydrophobicity cannot be obtained as a whole particle.

  The compound (b-2) such as dialkyldimethoxysilane has two reactive groups (methoxy groups). Similarly, even if an alkyl group is added to the surface of the silica particles, one methoxy group becomes a hydroxyl group. The amount of is almost unchanged and sufficient hydrophobicity cannot be obtained.

  On the other hand, since the compound (c-1) such as trialkylmonomethoxysilane has only one reactive group, when it reacts with silica particles, silanol groups can be reduced and an alkyl group can be added. However, since there are three hydrophobic groups such as an alkyl group, the steric hindrance during the reaction is large, and it is difficult for another (c-1) compound to react with a nearby silanol group with which the (c-1) compound has reacted. When trimethylmonomethoxysilane, which has the least steric hindrance, is used, there is little steric hindrance, and another trimethylmonomethoxysilane reacts to some extent with the nearby silanol group reacted with trimethylmonomethoxysilane. The performance of the particles is insufficient, and sufficient hydrophobicity cannot be obtained as a whole particle. On the other hand, the compound (c-1) having a large alkyl group such as an ethyl group or a propyl group has a large steric hindrance as described above, so that the reaction does not proceed to an amount that imparts sufficient hydrophobicity to the silica particles.

  For the above reasons, the amount of silanol groups cannot be reduced, but an (b-1) or (b-2) compound (becomes the component (B) of the present application after the reaction) to which an alkyl group or the like can be added, and By reacting both of the compounds (c-1) capable of reducing silanol groups (which will become the component (C) of the present application after the reaction) with silica particles (corresponding to the component (A) of the present application), Hydrophobic groups can be increased and silanol groups can be decreased, and as a result, the hydrophobicity of the silica particles can be greatly increased. However, when the component (B) is only the reaction product of the compound (b-1), the amount of the hydroxyl group increases so much that the effect of reducing the hydroxyl group by the compound (c-1) cannot be obtained sufficiently. Therefore, the component (B) must always contain the reaction product of the compound (b-2). In addition, since the compound (b-2) has two alkyl groups and the like, if these groups are large, the reaction of the compound (c-1) may be hindered because steric hindrance occurs during the reaction. Therefore, it is preferable that the alkyl group of the compound (b-2) is small.

  In the case of the core-shell silica particles of the present invention, a silica compound layer containing the component (A), the component (B) and the component (C) is formed around the core resin, and each component may be mixed. Although it may be layered, it is preferable to form the components (B) and (C) after forming the component (A) around the resin because the resulting core-shell silica particles are highly hydrophobic. More preferably, the component (B) is formed after the component (A) is formed around the resin, and then the component (C) is further formed. Finally, by forming the component (C) (reacting the compound (c-1)), silanol groups on the particle surface can be surely reduced.

  The component (A) is silica that is formed around the core resin. If the amount of the component (A) is too small, the component (B) or the component (C) is difficult to form, or the obtained core-shell silica particles In some cases, the silica compound layer coated around the substrate is easily peeled off, and the hollow silica described later is easily broken. If the amount of component (A) is too large, the silica compound layer becomes too thick and the core-shell silica particles have a large particle size, making it impossible to obtain core-shell silica particles having the desired particle size, or producing hollow silica as described later. In some cases, the resin inside the particles cannot be eluted.

  As a specific reaction ratio, it is preferable to react so that it may become 0.1-3 mass parts of (a-1) compounds with respect to 1 mass part of resin, and 0.2-2 mass parts is more preferable. In addition, when making the hollow silica mentioned later, since there is a case where the silica compound layer becomes too thick when the component (A) is too much, a small hole cannot be formed in the silica compound layer, and the resin cannot be removed. -1) It is preferable to make a compound react so that it may become 0.3-1.0 mass part with respect to 1 mass part of resin, and 0.3-0.7 mass part is more preferable.

  In the core-shell silica particles of the present invention, the silica compound layer containing the component (A), the component (B) and the component (C) is formed around the resin as described above. Each component may be in any ratio, but 0.3 mol to 4 mol of silicon atom of component (B) and 0.01 to 0.01 mol of silicon atom of component (C) with respect to 1 mol of silicon atom of component (A). It is preferably formed so as to be 3 moles, 0.5 to 3 moles of silicon atoms of (B) component and 0.1 moles of silicon atoms of (C) component with respect to 1 mole of silicon atoms of (A) component. It is more preferable to react so that it may become -2 mol, The silicon atom of (B) component is 0.5-2 mol with respect to 1 mol of silicon atoms of (A) component, and the silicon atom of (C) component is 0 It is more preferable to react so that it may become 5-2 mol. If the proportion of the component (B) and the component (C) with respect to the component (A) is too small, the hydrophobicity of the particles may not be increased, and if the proportion is too large, unreacted substances may remain. Moreover, the ratio of the modified silica represented by the composition formula of the general formula (1) in the component (B) and the modified silica represented by the composition formula of the general formula (2) is 1 mol of silicon atoms of the component (A). On the other hand, the silicon atom of the modified silica represented by the composition formula of the general formula (1) is 0 to 1 mol, and the silicon atom of the modified silica represented by the composition formula of the general formula (2) is 0.3 to 3 mol. The silicon atom of the modified silica represented by the composition formula of the general formula (1) with respect to 1 mole of the silicon atom of the component (A) is 0 to 0.5 mole, and the composition of the general formula (2) More preferably, the modified silica represented by the formula has a composition formula of 0.5 to 2.5 mol. If the silicon atom of the modified silica represented by the composition formula of the general formula (1) exceeds 1 mol, the hydrophobicity of the core-shell silica particles of the present invention may be greatly reduced.

The method for producing core-shell silica particles of the present invention is a production method characterized by reacting a silane compound represented by the following general formula (4) around a core made of a resin obtained by emulsion polymerization.
(R ¹ ) _n Si (OR ² ) _4-n (4)
(In the formula, R ¹ and R ² are hydrocarbon groups having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or Represents a halogenated alkyl group having 1 to 24 carbon atoms, and n represents a number of 0 to 3.)

  In the general formula (4), when n = 0, it becomes a silane compound forming the component (A), and examples of such a silane compound include tetraalkoxysilanes described as the compound (a-1). When n = 1, the silane compound forms the component (B). Examples of such silane compounds include the alkoxysilanes described as the compound (b-1). When n = 2, the silane compound forms the component (B). Examples of such silane compounds include the alkoxysilanes described as the (b-2) compound. Furthermore, when n = 3, the silane compound forms the component (C). Examples of such silane compounds include the alkoxysilanes described as the compound (c-1). Among these, preferred compounds are the same as the preferred compounds (a-1) to (c-1).

  As a specific production method, for example, various monomers are polymerized by emulsion polymerization as an aqueous solution in an emulsion state of about 1 to 40% by mass, and a silica compound (general formula ( In 4), 1 to 30 parts by mass of n = 0) is added to 10 parts by mass of the resin, reacted at 0 to 50 ° C. for 1 to 48 hours, and further aged at 50 to 80 ° C. for 1 to 24 hours. At this time, the catalyst may or may not be used. Examples of catalysts that can be used include strong acids such as sulfuric acid and toluenesulfonic acid; metal halides such as titanium tetrachloride, hafnium chloride, zirconium chloride, aluminum chloride, gallium chloride, indium chloride, iron chloride, tin chloride, and boron fluoride. ; Hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium carbonate; alcoholates; carbonates; aluminum oxide, calcium oxide, barium oxide, sodium oxide, etc. Metal oxides; Organometallic compounds such as tetraisopropyl titanate, dibutyltin dichloride, dibutyltin oxide; nitrogen atom-containing compounds such as ammonia and amines.

  By the above reaction, the component (A) is coated around the resin. Next, a modified silica compound for forming the component (B) (a mixture of n = 1 and n = 2 in the general formula (4), Alternatively, n = 2) is added and reacted under the same reaction conditions as above, and finally the modified silica compound (n = 3 in the general formula (4)) for forming the component (C) is the same as above. Then, the shell layer may be formed by adding and reacting.

  In the reaction for forming the component (B) and the component (C), it is preferable to use an organic solvent for the purpose of shortening the reaction time and improving the stability of the reaction system. Examples of the organic solvent that can be used include organic solvents such as methanol, ethanol, propanol, and butanol. When using these organic solvents, about 1-100 mass% should just be added with respect to the whole reaction system.

  If only the core-shell silica particles of the present invention are to be made hydrophobic, the component (B) only needs to use a compound (b-2) such as dimethylmethoxysilane, and the core-shell silica particles are provided with functions such as reactivity. In this case, it is sufficient to use a compound having a reactive group or the like in either or both of the compounds (b-1) and (b-2). It is preferable to use a (b-2) compound such as methoxysilane in combination.

  The hollow silica particles of the present invention are obtained by removing part or all of the resin that is the core of the core-shell silica particles of the present invention. The removal method is not limited, and examples thereof include a method of decomposing and removing a resin with an acid or an alkali, and a method of dissolving and removing with an organic solvent, but since the core resin can be efficiently removed, the organic solvent Is preferably used.

  Any organic solvent that can dissolve the core resin can be used, for example, benzene, toluene, xylene, tetrohydrofuran, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide. , Organic solvents such as dimethylacetamide, chloroform, dichloromethane, dichloroethane and the like. Among these solvents, tetrohydrofuran, methyl ethyl ketone, and methyl isobutyl ketone are preferable because the fine particles have high stability and the organic matter has high solubility.

The method for producing hollow silica particles of the present invention is a production method characterized in that a part or all of the core is removed from the core-shell silica particles of the present invention using a solvent. An example will be described.
When the core resin is coated with the silica compound layer of the shell layer, the solvent is water or an aqueous solution containing an organic solvent. These solvents represented by water may be replaced with an organic solvent in which the core resin dissolves. For example, an appropriate amount of an organic solvent is added to and mixed with an aqueous solution of core-shell silica particles, followed by filtration to remove the fine particles and the solvent. The organic solvent is further added to the fine particles after separation. By repeating this step, the aqueous solvent can be replaced with the organic solvent while removing the organic matter. For filtration, any filtration method may be used as long as it can fractionate fine particles. However, in the case of separating small particles having a particle size of 100 nm or less, an ultrafiltration membrane having a pore size of about 5 to 100 nm is used. Filtration is preferred.

  In order to smoothly perform filtration in the ultrafiltration described above, the size of the particles and the molecular weight of the organic matter constituting the resin are important factors. Usually, the filtration system contains particles, solvent, and organic matter dissolved in the solvent. However, when these mixtures are passed through a filter, the particles do not pass through the filter, and the solvent and organic matter pass through the filter. Separated. However, when the molecular weight of the organic substance constituting the resin obtained by emulsion polymerization is large, these organic substances dissolved in the solvent may not pass through the filter. Therefore, when manufacturing resin by emulsion polymerization, the molecular weight of the organic substance which comprises resin should be as small as possible. Therefore, it is preferable to use a chain transfer agent during emulsion polymerization. The chain transfer agent serves to reduce the molecular weight of the polymer.

  The hollow silica particles of the present invention obtained by removing the resin have cavities in the particles, but in order to completely remove the core, an organic substance removal step with an organic solvent or the like is performed for a long time, and a larger amount Organic solvents must be used. This is not very preferable from the viewpoint of economy. Therefore, in consideration of both the performance and economical efficiency of the hollow silica particles, the hollow silica particles may be in a state in which a small amount of the core organic matter remains. This is because when the amount of the organic matter constituting the remaining resin is a very small amount, various performances of the obtained hollow silica particles hardly change. The specific residual amount of organic matter that does not affect various performances is preferably 10% by mass or less of the entire core, more preferably 5% by mass or less, and further preferably 2% by mass or less. preferable.

  Core-shell silica particles or hollow silica particles immediately after production are dispersed in a solvent. Even in this state, the product can be obtained, but the solvent may be removed to form silica compound fine particles. Any method may be used for removing the solvent as long as it is a known method, and examples thereof include distillation under reduced pressure, drying by heating, spray drying, or a combination of these methods.

  The core-shell silica particles and hollow silica particles of the present invention can be produced freely as long as the particle diameter is 10 to 350 nm, and the resin produces particles of uniform size with little variation in particle diameter. Since it has the advantage that it can do, the core-shell silica particle and hollow silica particle which are finally obtained also have the particle | grains of a uniform magnitude | size with little dispersion | variation in a particle diameter.

  The core-shell silica particles and hollow silica particles of the present invention can be used for any application that can use conventionally known colloidal silica, hollow silica particles, etc., but because of their high hydrophobicity, Use in applications where it is added to organic solvents, resins, etc. is preferred. Examples of such applications include applications in the field of electronic materials and semiconductors.

Hereinafter, the present invention will be specifically described by way of examples. In the following examples and the like,% is based on mass unless otherwise specified.
<Method for Producing Compound of Example 1>
(Manufacture of core)
In a 1000 ml four-necked flask equipped with a thermometer, a nitrogen introduction tube and a stirrer, 50 g of styrene monomer, 500 g of distilled water, 4 g of dodecyltrimethylammonium chloride as an emulsifier, and 2.5 g of decanethiol as a chain transfer agent were substituted with nitrogen, The temperature was raised to 70 ° C. with stirring. After the temperature rise, 0.3 g of water-soluble azo polymerization initiator V-50 (manufactured by Wako Pure Chemical Industries, Ltd.) was added as an initiator and reacted at 70 ° C. for 3 hours to give a milky white liquid polystyrene emulsion (core )

(Formation of shell layer)
The obtained polystyrene emulsion (111.3 g, polystyrene content: 10 g) was put into a 2000 ml four-necked flask equipped with a thermometer, a nitrogen introduction tube and a stirrer, and 876 g of distilled water was further added to perform nitrogen substitution. After adjusting the temperature in the system to 25 ° C., 12.67 g of tetramethoxysilane (5 g in terms of SiO ₂ ) was added while stirring the system, and the reaction was allowed to proceed for 24 hours at 25 ° C. Subsequently, while maintaining the temperature of the solution at 25 ° C., 8.11 g of dimethyldimethoxysilane (R ′ in the general formula (2) is 5 g in terms of a methyl group compound) is added while stirring in the system. The reaction was carried out for 24 hours while maintaining the temperature. Further, while maintaining the temperature of the solution at 25 ° C., 6.42 g of trimethylmonomethoxysilane (5 g of R ″ in the general formula (3) is 5 g in terms of a methyl group compound) was added while stirring in the system. The mixture was allowed to react at 24 ° C. for 24 hours, then heated to 70 ° C. and further reacted for 6 hours to obtain a 2.0% solution of the core-shell silica particles of the present invention (Example 1).

<The manufacturing method of Examples 2-17 and Comparative Examples 1-11>
A core was produced in the same manner as in the method for producing the compound of Example 1, and the same amount of component (A) as in Example 1 was coated on the core. Then, according to the ratios shown in Tables 1 and 2 below, (B The shell layer is formed in the same manner as the compound of Example 1 in the order of the silane compound forming the component and the silane compound forming the component (C), and the core-shell silica of Examples 2 to 16 and Comparative Examples 1 to 11 Particles were obtained. In Example 17, the silane compound for forming the component (A) was changed from 12.67 g of tetramethoxysilane to 17.33 g of tetraethoxysilane (5 g in terms of SiO ₂ ), and the others were the same as in Example 1. In Comparative Example 11, only component (A) was coated. Tables 1 and 2 show the proportions of the components (A) to (C) (molar ratio of silicon element) and the types of silane compounds used to form the components (A) to (C). ) And (C), the types of R, R ′ and R ″ in the general formulas (1) to (3) are shown.

<Test 1: Measurement of hydrophobicity>
To 100 ml of a solution in which the mixing ratio of water and methanol was changed, 0.2 g of the particles prepared above were added and stirred for 5 minutes with a magnetic stirrer. For the solution in which the added particles were wetted in the solution and dispersed in the whole solution, the value of methanol volume% of the solution having the smallest amount of methanol was defined as the degree of hydrophobicity. For example, if the methanol concentration is 30% aqueous solution (volume ratio), the particles are dispersed in the solution, and if the 29% aqueous solution (volume ratio) is not dispersed, the degree of hydrophobicity is 30. In the 100% methanol solution, all particles are dispersed, and as the amount of water increases (methanol decreases), particles with a high degree of hydrophobicity do not disperse. Therefore, the larger the number, the higher the degree of hydrophobicity. In addition, the solution used what changed the compounding ratio by 1% (volume ratio) unit, and the result was shown in Table 3.

<Test 2: Measurement of solubility>
1 g of the particles prepared above was added to 100 ml of MIBK (methyl ethyl ketone), and the state after mixing was observed. When the mixed MIBK solution is a homogeneous solution, 1 g of the particles is further added, and the same operation is continued until the MIBK solution is finally whitened or gelled. The particles before the MIBK solution is whitened or gelled. The solubility was calculated from the sum of the added amounts of and the results are shown in Table 3.

<Production of hollow silica>
Ultrafiltration was performed by adding 3000 ml of tetrahydrofuran (THF) to 500 ml of the core-shell silica particles of Example 1 (aqueous solution with a particle concentration of 2.0%). The filtration device used was Nano Filter Demi (manufactured by Noritake Company Limited), and the pore size of the filter used was 100 nm. While removing the filtered solvent and resin component by ultrafiltration, the same amount of THF as the removed solvent was added to the system and the filtration was continuously advanced. When 10000 ml of new THF was added, Filtration was terminated to obtain a THF solution (Example 18) having a particle concentration of 2.0%. The water content of the obtained solution was 0.1%.
Similarly to the above, the cores of the particles of Examples 2 to 17 and Comparative Examples 1 to 11 were removed, and the THF solutions of the hollow silica particles of Examples 19 to 34 and Comparative Examples 12 to 22 were used. Manufactured and tested for hydrophobicity and solubility. The results are listed in Table 4. The THF solution of the hollow silica particles was used for the test after removing the solvent THF by drying under reduced pressure.

<Reflectance>
0.1 g of a wetting agent (trade name: MegaFuck F-470 (manufactured by DIC)) was added to 2 g of polymethyl methacrylate resin (trade name: Sumipec LG (manufactured by Sumitomo Chemical Co., Ltd.)), and Example 18 was added thereto. 2 g of each of the hollow silica particles of Comparative Examples 12 and 18 and 95.9 g of methyl isobutyl ketone as a solvent were added and mixed uniformly. The obtained three types of solutions were coated on a glass substrate having a refractive index of 1.54 using a bar coater, dried at room temperature for 3 hours, and then dried at 120 ° C. for 1 hour to form a coating having a thickness of 100 nm. A membrane was obtained.

After observing the appearance of the obtained coating film and further measuring the reflectance (wavelength 550 nm) using V-530 (manufactured by JASCO Corporation), the refractive index of the coating film was calculated from the following formula. The respective results are shown in Table 5.
Reflectance ^{_{R = ((n s -n 1}} 2) / (n s + n 1 2)) 2
n _s : refractive index of substrate (1.54)
n ₁ : refractive index of coating film

  As described above, the hollow silica particles of the present invention can greatly reduce the reflectance and refractive index of the resin coating film, and therefore can be applied to antireflection films and the like. In Comparative Examples 12 and 18, since the resin whitened, the reflectance did not become a constant value, and the measurement was abandoned.

Claims (7)

(A) Silica represented by the composition formula of SiO ₂ as component, (B) Component modified formula of the general formula (2), or modified silica represented by the composition formula of the general formula (1) and the general formula (2), And a shell layer containing a modified silica represented by the composition formula of the general formula (3) as the component (C) and a core made of a resin obtained by emulsion polymerization.
RSiO _3/2 (1)
(In the formula, R is a hydrocarbon group having 1 to 24 carbon atoms which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 to 1 carbon atoms). Represents 24 halogenated alkyl groups.)
R ′ ₂ SiO (2)
(In the formula, R ′ is a hydrocarbon group having 1 to 24 carbon atoms in total which may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)
R " ₃ SiO _1/2 (3)
(In the formula, R ″ represents a hydrocarbon group having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or 1 carbon atom) Represents a halogenated alkyl group of ˜24.)   (A) The silicon atom of the modified silica represented by the general formula (1) is 0 to 1 mol and the silicon atom of the modified silica represented by the general formula (2) is 0.3 to 1 mol per 1 mol of the silicon atom of the component (A). 3. The core-shell silica particles according to claim 1, wherein the silicon atom of the modified silica represented by 3 mol and the general formula (3) is 0.01 to 3 mol.   The core-shell silica particles according to claim 1, wherein R ′ in the general formula (2) and R ″ in the general formula (3) are both methyl groups.   The shell layer forms layers from the inside in the order of the component (A), the component (B), and the component (C). The method according to any one of claims 1 to 3, Core shell silica particles.   The hollow silica particle obtained by removing a core from the core-shell silica particle as described in any one of Claims 1-4. The method for producing core-shell silica particles according to any one of claims 1 to 4, wherein a silane compound represented by the following general formula (4) is reacted around a core produced by emulsion polymerization.
(R ¹ ) _n Si (OR ² ) _4-n (4)
(In the formula, R ¹ and R ² are hydrocarbon groups having 1 to 24 carbon atoms that may be substituted with any group selected from an amino group, a mercapto group, a (meth) acryl group, and an epoxy group, or Represents a halogenated alkyl group having 1 to 24 carbon atoms, and n represents a number of 0 to 3.)   A method for producing hollow silica particles, wherein the core is removed from the core-shell silica particles produced by the production method according to claim 6 using a solvent.