JP5545694B2 - Carbon-containing metal oxide hollow particles and method for producing the same - Google Patents

Description

  The present invention relates to a metal oxide hollow particle containing carbon, more specifically, a metal oxide hollow particle obtained by highly complexing carbon, characterized by having a high porosity and a single particle size distribution, and The present invention relates to a method for producing the carbon-containing metal oxide hollow particles.

  Hollow particles are widely used as microcapsules that contain various functional substances inside the particles, and by utilizing the unique light scattering characteristics due to the internal pores, they can be applied to paper, fibers, leather, glass, metals, etc. In the fields of coatings, paints and cosmetics, it is known that they are also useful as light scattering agents and light scattering aids for imparting performance such as brightness, gloss, opacity and whiteness. Furthermore, since the inside is hollow, a bulky and light weight, sound insulation, and heat insulation effect can be expected. Among hollow particles, hollow particles of metal oxides such as silica, titanium oxide, and zirconium oxide are particularly useful industrially because they are excellent in structural stability and chemical stability, and have a large surface area based on the hollow structure. Application as a utilized catalyst or catalyst carrier is also expected.

  Several methods have been proposed for producing such metal oxide hollow particles. For example, as a method of utilizing a reaction at the liquid-liquid interface, first, an aqueous solution of an inorganic compound containing an alkali metal salt is prepared, and an organic solvent is added and mixed therewith, so that oil-in-water (O / W) milk The resulting emulsion is further added to and mixed with an organic solvent containing a lipophilic surfactant to form an oil-in-water-in-oil (O / W / O) emulsion. Finally, a method for obtaining inorganic hollow fine particles by mixing an emulsion with an aqueous solution of a compound capable of forming a water-insoluble precipitate by an aqueous solution reaction with the inorganic compound is disclosed (for example, see Patent Document 1). . In addition, an aqueous solution of an inorganic compound is mixed and emulsified with an organic solvent using a surfactant to form a water-in-oil (W / O) emulsion, and this is mixed with another aqueous solution to cause precipitation reaction at the water droplet interface. After the formation of an inorganic shell, a method of obtaining hollow particles by removing by-products, surfactants and the like is disclosed. However, these methods include a complicated process of emulsifying with a surfactant, require skill in production, have a wide particle size distribution of the obtained hollow particles, and have strength and particle size reproducibility. There was a problem that it was not good.

  As a method for obtaining metal oxide hollow particles having a monodisperse particle size distribution, core-shell type particles having a metal oxide layer formed on the surface of a monodisperse particle as a template were prepared, and the metal oxide was oxidized. There has been proposed a method for removing the template inside without destroying the shell layer of the object. For example, one of the methods for producing polymer-metal oxide core-shell type fine particles using a template is an alternating lamination method (see, for example, Patent Document 3). This is a method of obtaining hollow particles by coating colloidal particles with alternating layers of oppositely charged nanoparticles and polyelectrolytes and removing the colloidal core.

  Similarly, titanium oxide hollow particles can be obtained by electrostatically laminating fine particles of titanium oxide, titania nanosheets, and titanium oxide precursor monomers on polymer fine particles using an alternate lamination method, and then removing the polymer component. (For example, refer nonpatent literatures 1-3.).

  In such an alternate lamination method, it is advantageous to obtain metal oxide hollow particles having a shell of any thickness by arbitrarily changing the number of laminations on the template particle as a core. It is necessary to re-disperse the particles after removing and washing excess components that have not been adsorbed for each adsorption operation by a centrifugal operation or the like, and the operation before removing the template becomes a very complicated process, which is not practical.

  On the other hand, monodisperse polymer particles whose surface is modified with silanol (Si-OH) groups are synthesized using a silane coupling agent, and silica is deposited on the surface using this as a seed particle. A method for obtaining silica hollow particles by removal is disclosed (for example, see Non-Patent Document 4). According to this method, silica single particles are not generated in the liquid, and the silica condensation reaction occurs selectively on the polymer particles, so there is no need to finally remove the non-hollow silica single particles. This is a great advantage. In addition, it is reported that silica is firmly bonded on the polymer particle by a covalent bond, and stable particles having a shell with a thickness of about 20 nm can be obtained.

  However, the synthesis of a polymer template having a silanol group on the surface requires a process of post-adding 3- (trimethoxysilyl) propyl methacrylate during the progress of the polymerization reaction, and therefore requires precise reaction control. When the ethanol solution of tetraethoxysilane, which is a silica source, is dropped, it has to be performed at a very low addition rate of 1 ml / h, and there is a problem that it takes a long time.

  On the other hand, a method of forming a metal oxide film on monodisperse polymer particles by an operation of hydrolyzing a metal alkoxide or metal salt in the presence of core polymer particles has also been proposed (for example, see Non-Patent Document 5). .) In addition, a metal compound formed by dispersing monodisperse polymer particles in an alcohol solution of silicon alkoxide or titanium alkoxide and hydrolyzing silicon alkoxide, titanium alkoxide, or the like in the alcohol solution or alcohol / water solution. A method of obtaining hollow particles by calcination after coating on core-polymer particles is also disclosed (for example, see Patent Document 4).

  In this method, the polymer particle surface and hydrolyzed metal ions, or the complex formed by hydrolysis, adsorb onto the surface of the core polymer particle to form a coating layer, or very small metal compound fine particles are formed. A mechanism has been considered in which this adsorbs onto the surface of the core polymer fine particles, and a metal compound layer grows on the surface of the particle, and the mechanism of adsorption is mainly due to electrostatic interaction. Accordingly, the core polymer particles inevitably become polymer fine particles having a surface charge opposite to that of the metal oxide forming the coating layer. In these techniques, it is advantageous that a coating layer of metal oxide can be formed on the polymer template by a single operation of mixing the polymer template and the precursor solution of metal oxide. It is necessary to prepare template particles with different surface charges depending on the metal oxide. Often, metal oxide-only particles that do not adsorb on the polymer surface remain in the system and are removed before hollowing treatment such as firing. It was a problem that had to be left.

  In addition, a method using a polymer particle having an amphoteric ion surface as a template has also been reported (for example, see Non-Patent Document 6). In this method, a dispersion of polystyrene modified with amino groups and carboxylate groups is added to an aqueous sodium silicate solution and stirred to form a silica coating on the polymer template. However, this method requires a long reaction time of 24 hours after adjusting the pH in order to coat the silica on the polymer template.

  There has also been reported a method in which poly-L-lysine is further adsorbed on polymer particles surface-modified with amino groups and this is used as a polymer template. According to this method, it is considered that the amine on the polymer particles acts as a basic catalyst and promotes the condensation reaction of silicic acid on the polymer template to efficiently form a silica or titania coating layer (for example, (See Patent Document 7).

  As described above, many methods for forming a metal oxide film on a polymer template are known. The core component is obtained by baking the core-shell type particle of the polymer particle-metal oxide film or extracting the core polymer with a solvent. The monodisperse metal oxide hollow particles can be obtained by removing.

However, in the conventionally proposed metal oxide hollow particles, both the method using the emulsion and the method using the core polymer are selected so that the organic substance serving as a template can be removed as easily as possible to form a particle structure. An object of the present invention is to obtain hollow particles made of a highly pure metal oxide by completely removing the liquid and the core used in the above. In this case, hollow particles of metal oxide, such as silica, titania, zirconia, etc., which do not absorb themselves in the visible light region, that is, have no color, are suitable for use as white pigments or white light scatterers as coloring materials. It was limited.
JP-A 63-258642 JP-A-6-330606 Special table 2003-522621 gazette JP-A-6-142491 Rachel A. Caruso, Andrew Susha, and Frank Caruso, Chem. Mater. 2001, 13, 400-409 Masaki Iida, Takayoshi Sasaki, and Mamoru Watanabe, Chem. Mater. 1998, 10, 3780-3782. Frank Caruso, Xiangyang Shi, Rachel A. et al. Caruso, and Andrew Susha, Adv. Mater. 2001, 13; 10, May 17, 740-744 I. Tissot, J .; P. Reymond, F.M. Leftebvre, and E.M. Bourgeat-Lami, Chem. Mater. , 2002, 14, 1325-1331 Arnout Imhof, Langmuir, 2001, 17, 3579-3585 Jeroen J.H. L. M.M. Cornelissen, Eric. F. Connor, Ho-Cheol Kim, Victor Y. et al. Lee, Teddie Magibitang, Philip M. et al. Rice, Willi Volksen, Linda K. et al. Sundberg and Robert D. Miller, Chem. Commun. , 2003, 1010 Jiang Yang, Johan U. Lind, and William C.L. Trogler, Chem. Mater. 2008, 20, 2875-2877

  In view of the above circumstances, an object of the present invention, that is, an object is to provide monodisperse metal oxide hollow particles that exhibit vivid color other than white and a method for efficiently producing the same.

  As a result of diligent research to solve the problems of the prior art, the present inventors used monodisperse polymer fine particles having both a hydrophilic polymer layer solvated in an aqueous medium and an amino group as a template, After forming a metal oxide film on the surface, the polymer fine particles are removed by firing, whereby monodisperse hollow particles having a thin thickness made of a metal oxide highly complexed with carbon can be efficiently obtained. The present inventors have found that vivid colors of different colors are shown depending on the particle size, and have completed the present invention. The monodispersion in the present invention means that the histogram in the particle size distribution shows a single peak, and the coefficient of variation (hereinafter referred to as the standard deviation of the particle size distribution in the single peak divided by the average particle size). , Abbreviated as dispersion coefficient)) is 0.1 or less.

  That is, the present invention relates to hollow particles composed of carbon-containing metal oxides, more specifically, carbon-containing monodisperse metal oxide hollow particles having a single particle size distribution and high porosity, and simple production thereof. A method is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the hollow particle which consists of a metal oxide containing carbon with the monodispersion and high porosity which show a vivid color development can be provided. The carbon-containing metal oxide hollow particles are monodisperse polymer fine particles having both a hydrophilic polymer layer solvated in an aqueous medium and an amino group on the surface, which is the production method of the present invention, as a template. After the oxide film is formed, the polymer fine particles are removed by baking, and the film can be obtained in a simple and reproducible manner. The resulting carbon-containing metal oxide hollow particles have different colors depending on the particle size and carbon content, and can display various colors. The metal oxide hollow particles can also exhibit different color development depending on the position of the light source and the observation direction.

  Therefore, the carbon-containing metal oxide hollow particles of the present invention utilize their unique color development properties in the fields of coatings and paints, and give vivid color development on various substrates such as paper, fiber, leather, plastic, metal, etc. It can be applied as a pigment for Also, it can be applied to a security label using a characteristic that shows different color depending on the position of the light source and the observation direction. Furthermore, it can be applied to cosmetics utilizing light diffusibility, water absorption, and oil absorption by a hollow structure, and can also be used as an ink jet receiving layer. Furthermore, since the heat conduction and sound conduction can be suppressed due to the hollow structure, it can be applied as a heat insulating material or a sound insulation material, and the mass in the same volume can be reduced, so that it can be used as a lightening agent. Furthermore, the carbon composite monodispersed hollow metal oxide particles of the present invention can be applied as various catalysts and catalyst supports.

Furthermore, the method for producing metal oxide hollow particles of the present invention comprises a hydrophilic polymer layer solvated in an aqueous medium and monodisperse polymer fine particles having both amino groups, or a hydrophilic polymer layer solvated in an aqueous medium and amino. By using monodisperse polymer fine particles having both a group and a carboxy group as a template, the solution of the metal oxide precursor is mixed with the dispersion of the monodisperse polymer fine particles and stirred for a short time. An operation of selectively forming a metal oxide film on the surface of the fine particles, and thereafter carbonizing a part of the polymer fine particles by baking and compositing a part thereof with the metal oxide film To produce carbon-containing metal oxide hollow particles having a single particle size distribution and a high porosity, good reproducibility and high efficiency. High its usefulness since the top is simple. Hereinafter, the term carboxy group in the specification is read as a carboxyl group .

The present invention is described in detail below.
The carbon-containing metal oxide hollow particle of the present invention is a hollow particle having a hollow inside, and is composed of a shell mainly composed of a metal oxide and carbon, and the thickness of the shell wall is 5 nm to 30 nm. And it is monodisperse particle | grains with an average particle diameter of 50 nm-1000 nm. The metal oxide and the carbon, specifically, the metal oxide and the carbon are combined in the nanometer order, thereby suppressing random light scattering due to the specific refractive index distribution derived from the hollow structure, As a result of emphasizing specific diffracted light and reflected light, the material also exhibits vivid color development. In this respect, it is very different from the conventional hollow particles containing a metal oxide as a main constituent component that do not show color development other than white.

  The method for producing carbon-containing metal oxide hollow particles of the present invention is mainly based on the following steps. That is, monodisperse polymer fine particles (X) having a hydrophilic polymer layer (x1) and an amino group (x2) that can be solvated in an aqueous medium, or a hydrophilic polymer layer (x1) that can be solvated in an aqueous medium, Monodisperse polymer fine particles (X) having an amino group (x2) and further a carboxy group (x3) are dispersed in an aqueous medium, the monodisperse polymer fine particles (X) are used as a template, and a metal oxide ( Y ′) a first step of forming a film, and thereafter, while removing the monodisperse polymer fine particles (X) by firing, a part thereof is carbonized to be combined with a metal oxide film to form carbon. A second step of obtaining hollow metal oxide particles.

  Here, the hydrophilic polymer layer (x1) that is solvated in the aqueous medium does not simply have a hydrophilic functional group on the surface of the polymer fine particles, but is constant from the surface of the polymer fine particles in the aqueous medium. This means that there is a polymer chain having a spatial expansion, and this is different from Non-Patent Document 6 in this respect. That is, the monodisperse polymer fine particle (X) used as a template in the present invention has a core having a hydrophilic corona or a hydrophilic shell layer outside the core (core) polymer fine particle that does not dissolve in an aqueous medium. Corona type or core-shell type fine particles. In the present invention, the metal alkoxide (Y) is concentrated in the hydrophilic polymer layer (x1), and the amino group (x2) and the carboxy group (x3) present therein are hydrolyzed by the metal alkoxide (Y). It functions efficiently as a catalyst for decomposition and condensation reaction (sol-gel reaction), and a film of metal oxide (Y ′) can be easily formed on the monodisperse polymer fine particles (X). In addition, the formed film made of the metal oxide (A) may further undergo a dehydration condensation reaction due to hydrogen bonding with the hydrophilic polymer layer (x1), or when the hydrophilic polymer has a hydroxy group. Therefore, the composite of the metal oxide (A) and the carbon can be easily realized by the firing process. In addition, even after a metal oxide coating layer in which the metal oxide (Y ′) and the hydrophilic polymer layer (x1) are complexed by the sol-gel reaction, a part of the hydrophilic polymer layer exists on the outermost surface. After firing, a special form in which carbon exists not only inside but also on the outermost surface can be realized.

The presence of the hydrophilic polymer layer (x1) solvated in the aqueous medium and having a certain spatial extent is, for example, a state in which the monodisperse polymer fine particles (X) are dispersed in the deuterated aqueous medium. This can be confirmed by performing ¹ H-NMR measurement. Further, utilizing the fact that this hydrophilic polymer layer (x1) has almost no substantial volume in the dry state, the particle size in the dry state is observed with an electron microscope, a surface probe microscope, etc. The presence of the hydrophilic polymer layer (x1) and the size of the spatial spread can also be confirmed by comparing with the particle size in the aqueous medium estimated by the light scattering method. In addition, for example, when a polymer composed of N-substituted acrylamide or N, N-disubstituted acrylamide or a copolymer obtained by using these as a part of the raw material is present outside the fine particles. It is known that a lower critical eutectic temperature exists. When the temperature is higher than the lower critical eutectic temperature, the outer layer exhibits hydrophobicity and thus does not solvate with an aqueous medium.However, when the temperature is low, the outer layer becomes hydrophilic and solvates. Have. Accordingly, in the case of such fine particles having a specific polymer on the outside, the particle size in the aqueous medium changes depending on the temperature, and from such a difference, it is solvated in the aqueous medium. The presence of the hydrophilic polymer layer (x1) having a certain spatial extent and the thickness of the layer can be estimated.

  In the present invention, the size of the spatial extension of the hydrophilic polymer layer (x1) in the aqueous medium described above can be preferably 5 nm to 200 nm. ) Is preferably used in order to efficiently form the coating layer.

  As an aqueous medium used in the present invention, water is used alone, lower alcohol such as methanol, ethanol and isopropanol, polyhydric alcohol such as ethylene glycol, propylene glycol, butanediol, diethylene glycol and triethylene glycol, acetone, Mention may be made of ketones such as methyl ethyl ketone and ethers such as tetrahydrofuran alone or in a mixture of a plurality of types.

[Monodisperse polymer fine particles (X)]
The monodisperse polymer fine particles (X) used as a template in the present invention may be any as long as the above conditions are satisfied, and the production method is not limited at all. For example, it can be obtained by various fine particle production methods such as emulsion polymerization, precipitation polymerization, and dispersion polymerization.

  The average particle size of the monodisperse polymer fine particles (X) used in the present invention is selected according to the purpose. However, the metal oxide hollow particles obtained by firing after forming a film made of the metal oxide (Y ′) on the polymer fine particles (X) have sufficient strength and the desired color development. From the viewpoint of increasing the strength of the polymer fine particles, the polymer fine particles (X) in the dry state are preferably particles having an average particle diameter of 50 nm or more and 1000 nm or less.

  The introduction of the hydrophilic polymer layer (x1) and the amino group (x2) into the polymer fine particles may be introduced at the time of polymerizing the fine particles by a combination of a polymerization initiator and a monomer. A core-corona type or core-shell type particle may be obtained by synthesizing and introducing it into the surface of the polymer fine particle by a chemical reaction. Further, the hydrophilic polymer layer (x1) and the amino group (x2) may be introduced separately, or the hydrophilic polymer layer (x1) having an amino group (x2) may be introduced. Further, apart from the hydrophilic polymer layer (x1) having an amino group (x2), an amino group (x2) can be further introduced on the surface of the polymer fine particle. Furthermore, monodisperse polymer fine particles made of an amphiphilic polymer having an amino group-containing polymer chain forming a shell layer and a polymer chain forming a core part may be used.

  Further, in obtaining the metal oxide hollow particles by the production method of the present invention, the monodisperse polymer fine particles (X) further have a carboxy group (x3) from the point that the sol-gel reaction proceeds more effectively. Is preferred. Preparation of polymer fine particles having a hydrophilic polymer layer (x1), an amino group (x2), and a carboxy group (x3) on the surface is carried out by introducing an amino group (x2), a carboxyl group (x3), and an amino group (x2). It can be suitably performed by using a polymer having an amino acid or an amino acid residue.

  Specifically, one form of monodisperse polymer fine particles (X) having a hydrophilic polymer layer (x1) on the surface is hollow polymer fine particles already provided by the present inventor as Japanese Patent Application Laid-Open No. 2007-291359. In detail, the hollow polymer fine particles themselves obtained by performing a radical polymerization reaction in the form of a pseudo-emulsion in an aqueous medium between a radically polymerizable water-soluble monomer (α1) and a radically polymerizable water-insoluble monomer (α2). Or an amino group (x2) introduced therein. The hollow polymer fine particles have a hydrophilic polymer layer (x1) on the surface and act as core-shell type polymer particles.

  In particular, from the point that amino group (x2) can be easily introduced, a single amount containing radically polymerizable water-soluble monomer (α1) and radically polymerizable water-insoluble monomer (α2) It is preferable that the body group (α) is composed of a shell wall containing a copolymer obtained by polymerizing an amino group-containing initiator as a main constituent, and coloration of the resulting metal oxide hollow particles From the viewpoint of enhancing the property, it is preferable to use hollow polymer fine particles having a shell wall thickness of 5 nm to 80 nm. The hollow polymer fine particles obtained by this method have an amino group derived from the initiator introduced on the surface thereof and can be suitably used as a template of the present invention as it is.

  The amino group-containing initiator is not particularly limited, and various initiators can be used. For example, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2 ′ -Azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2, 2'-azobis [N- (2-carboxyethyl) 2-methylpropionamide], 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2 '-Azobis 2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2 2,2′-azobis (2-methylbutanamidooxime) dihydrochloride tetrahydrate, etc., and 2,2′-azobis (2-amidinopropane) dihydrochloride is particularly preferred.

  Another form of the monodisperse polymer fine particles having the hydrophilic polymer layer (x1) is provided with a crosslinked hydrophilic polymer shell layer on the core particle. For the core-shell type fine particles, the core part and the shell layer may be prepared continuously, or the fine particles to be the core part may be prepared, and the shell layer may be separately prepared using this as a seed.

  For example, when the core part and the shell layer are separately prepared stepwise, the core part of the core-shell type fine particles is preferably used as long as it is a monodisperse particle, whether it is hollow or solid. be able to. Solid polymer fine particles can be prepared by various methods such as microgel method, emulsion polymerization method, soap-free emulsion polymerization method, seed emulsion polymerization method, two-stage swelling method, dispersion polymerization method, suspension polymerization method, etc. In addition, commercially available monodisperse polymer fine particles may be used. The monomer used for the purpose of synthesizing solid polymer fine particles is not particularly limited, and examples of the water-soluble monomer having an amide group as a radical polymerizable water-soluble monomer include acrylamide, N-ethylacrylamide, and N-ethyl. Methacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide, N-cyclopropylacrylamide, N-cyclopropylmethacrylamide, N, N-dimethylacrylamide, N , N-diethylacrylamide, N, N-dimethylaminopropylacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide, etc. Substituted (meth) acrylamide and N- disubstituted (meth) acrylamide, N- hydroxyethyl acrylamide, acryloyl morpholine, N- vinylpyrrolidone, diacetone acrylamide, N, N'-methylene bis-acrylamide. Examples of the water-soluble monomer having an amino group include allylamine, N, N-dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, and the like. Examples of the water-soluble monomer having a carboxy group include acrylic acid, methacrylic acid, and maleic acid. Examples of the water-soluble monomer having a hydroxy group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxy Examples thereof include ethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 1,4-cyclohexanedimethanol monoacrylate and the like. Examples of water-soluble monomers having a sulfonic acid group include styrene sulfonic acid, sodium styrene sulfonate, lithium styrene sulfonate, ammonium styrene sulfonate, ethyl styrene sulfonate, cyclohexyl styrene ester, 2-acrylamido-2-methylpropane A sulfonic acid etc. are mentioned. Furthermore, a quaternized monomer obtained by quaternizing a monomer synthesized by reacting vinyl pyridine or glycidyl methacrylate with an organic amine may be used.

  Furthermore, as a radical polymerizable water-insoluble monomer, acrylates include, for example, butyl acrylate, lauryl acrylate, cyclohexyl acrylate, phenyl acrylate, isobornyl acrylate, glycidyl acrylate, tert-butyl-α-trifluoro. Examples include methyl acrylate, 1-adamantyl-α-trifluoromethyl acrylate, (3-methyl-3-oxetanyl) methyl acrylate, acryloylpropyltrimethoxysilane, acryloylpropyltriethoxysilane, methyl acrylate, and ethyl acrylate. I can do it. Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, stearyl methacrylate, glycidyl methacrylate, allyl methacrylate, 2 2,2-trifluoroethyl methacrylate, (3-methyl-3-oxetanyl) methyl methacrylate, methacryloylpropyltrimethoxysilane, methacryloylpropyltriethoxysilane, and the like. These monomers can be used alone or in admixture of two or more. Hereinafter, (meth) acrylate used in the text is used as a general term for acrylate alone, methacrylate alone and mixtures thereof unless otherwise specified.

  Moreover, what has cyclic ether structures, such as glycidyl (meth) acrylate and oxetane (meth) acrylate, is also mentioned as a water-insoluble monomer.

  As the water-insoluble monomer, for example, styrene compounds, vinyl esters, vinyl ethers, bisvinyl compounds, etc. other than (meth) acrylates may be used alone or in combination of two or more.

  The styrenic compound is a compound having a styryl group. For example, styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-, m-, p-chlorostyrene, p-ethylstyrene, p- tert-butoxystyrene, m-tert-butoxystyrene, p-acetoxystyrene, p- (1-ethoxyethoxy) styrene, p-methoxystyrene, styryltrimethoxysilane, styryltriethoxysilane, vinylnaphthalene, vinylbiphenyl, vinylanthracene And vinylpyrene.

  Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl monochloroacetate, vinyl pivalate, and vinyl butyrate.

  Examples of the vinyl ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, allyl vinyl ether, cyclohexane dimethanol monovinyl ether, Examples include 1,4-butanediol divinyl ether, nonanediol divinyl ether, cyclohexanediol divinyl ether, cyclohexanedimethanol divinyl ether, trimethylpropane trivinyl ether, pentaerythritol tetravinyl ether, and phenyl vinyl ether.

  Furthermore, bifunctional di (meth) acrylates such as ethylene di (meth) acrylate, diethylene (meth) acrylate, polyethylene di (meth) acrylates such as triethylenedi (meth) acrylate, propylene di ( Polypropylene di (meth) acrylates such as (meth) acrylate, dipropylene di (meth) acrylate, tripropylene di (meth) acrylate, glycerol di (meth) acrylate, etc. may be used alone or in combination of two or more. it can. In addition, it is also possible to produce core particles by copolymerizing one or more of vinyl pyridine, N-vinyl pyrrolidone and the like.

  When the polymerization reaction is carried out in an aqueous medium, various water-soluble polymerization initiators may be used as the polymerization initiator. In particular, when an amino group-containing initiator is used, the amino group derived from the initiator contains fine particles. Since it is introduced into the surface, it is more preferable.

  The shell layer is prepared by, for example, using the core fine particles as seed particles, adding a water-soluble polymerizable monomer and a cross-linking agent to the aqueous medium dispersion, and performing emulsion polymerization to form a hydrophilic layer on the outside of the core portion. A shell layer of the conductive polymer layer (x1) can be provided.

  Examples of the water-soluble polymerizable monomer used for the synthesis of the shell layer include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-cyclopropylacrylamide, N-isopropylacrylamide, Nn-propylacrylamide, methacrylamide, N-methylmethacrylamide, N-cyclopropylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-N- n-propylacrylamide, N, N-diethylacrylamide, N-ethyl-N-isopropylacrylamide, N-ethyl-Nn-propylacrylamide, N, N-diisopropylacrylamide, N-acryloyl One kind of acrylamide monomers such as loridone, N-acryloylpiperidone, N-acryloylmethylhomopiperazine, N-acryloylmethylpiperazine, or a crosslinked polymer obtained by polymerizing two or more of these monomers It can be used suitably. Moreover, what copolymerized these with acrylic acid, methacrylamide-propyl-trimethyl-ammonium chloride, 1-vinylimidazole, methacryloyloxyphenyldimethylsulfonium methylsulfate, etc. can be used conveniently.

  Examples of the crosslinking agent used for synthesizing the shell layer include ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, N, N′-methylenebisacrylamide, divinylbenzene, and the like. N, N′-methylene Bisacrylamide, ethylene glycol di (meth) acrylate, and divinylbenzene are preferably used.

  The polymerization initiator used for synthesizing the shell layer is not particularly limited as long as it is a water-soluble polymerization initiator, but it is preferable to use a persulfate or an amino group-containing azo compound. For example, potassium persulfate ( KPS), ammonium persulfate (APS), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2 , 2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis [N- (2-carboxyethyl) 2-methylpropionamide], 2 , 2′-azobis (1-imino-1-pyrrolidino-2-methylpropane] dihydrochloride, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] Prop } Dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2, 2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2'-azobis (2-methylbutanamidooxime) dihydrochloride tetrahydrate Among them, when the surface charge of the core particle is positive, an amino group-containing azo compound is used, and when the surface charge of the core particle is negative, a persulfate is used for polymerization. It is preferable because aggregation in the process can be prevented.

[Introduction of amino group (x2)]
As described above, the monodisperse polymer fine particles described above are polymerizable monomers having an amino group such as allylamine, N, N-dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, vinyl pyridine and the like as monomers at the time of particle synthesis. If a monomer is used or an initiator having an amino group such as 2,2′-azobis (2-amidinopropane) dihydrochloride is used, the fine particles can be suitably used as they are as a template of the present invention.

  On the other hand, when a polymerizable monomer or initiator having no amino group (x2) is used, both the hollow polymer fine particle and the core-crosslinked hydrophilic polymer shell fine particle are covalently bonded to the surface of the fine particle. By introducing the group (x2), it can be used as a template of the present invention. For the introduction of the amino group (x2), for example, a monomer having a cyclic ether structure such as glycidyl (meth) acrylate or oxetane (meth) acrylate was used as a polymerizable monomer when producing monodisperse fine particles. In some cases, the amino group (x2) can be introduced by reacting a compound having an amino group (x2) with a glycidyl group or oxetane group present on the surface of the fine particles. Further, in the case of using a compound having one or more of carboxy group, hydroxy group, amide group, and thiol group and an amino group, the reaction of these glycidyl group or oxetane group and amino group may be used. In addition, a compound having one or more of a carboxy group, a hydroxy group, an amide group, and a thiol group together with an amino group may be used and a reaction with these functional groups may be used.

  The compound having an amino group (x2) may have at least one amino group in its structure, and may be any of primary, secondary, and tertiary amines. Moreover, these amino groups (x2) can be used in the form of a base or neutralized. As the acid for neutralizing the amino group (x2), various acids such as hydrochloric acid, acetic acid, phosphoric acid, boric acid and sulfuric acid can be used, and the amino group (x2) is quaternized. May be.

  Specifically, as the compound, as an amino group-containing compound having one amino group in the structure, for example, methylamine, dimethylamine, trimethylamine, ethanolamine, diethanolamine, aminopropanol, aminoethanethiol, etc. Examples of polyamines include diamines such as ethylenediamine, diaminopropane, diaminobutane, diaminopentane, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, spermidine, spermine and the like. These hydrochlorides, acetates, phosphates, borates, sulfates and the like can also be used.

  In addition, one or more amino acid residues such as glycine, alanine, leucine, isoleucine, cysteine, glutamine, histidine, asparagine, serine, lysine, arginine, methionine, threonine, valine, etc. Low molecular and high molecular compounds selected from the group consisting of low molecular and high molecular compounds containing a skeleton, and various acids such as hydrochloric acid, acetic acid, phosphoric acid, boric acid, sulfuric acid and the like in the amino groups in these compounds Mention may also be made of compounds neutralized by use. These compounds having amino acid residues have an amino group (x2) and a carboxy group (x3) at the same time, and can introduce a carboxy group (x3) at the same time as the introduction of the amino group (x2). Since the monodisperse polymer fine particles having both the hydrophilic polymer layer (x1) solvated in the aqueous medium, the amino group (x2), and the carboxy group (x3) on the surface can be prepared, it is particularly preferably used. it can.

  Examples of amino group-containing polymers include, for example, polymers containing a skeleton of polyethyleneimine, polypropyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polylysine, polydimethylaminoethyl methacrylate, polydimethylaminoacrylate, and chitosan. Examples thereof include homopolymers or copolymers selected from the group, and compounds obtained by neutralizing amino groups in these compounds with various acids such as hydrochloric acid, acetic acid, phosphoric acid, boric acid and sulfuric acid.

  As another form of the monodisperse polymer fine particles (X) having the hydrophilic polymer layer (x1) on the surface, the hydrophilic polymer having an amino group (x2) is directly on the surface of the polymer fine particles corresponding to the core portion. It is a combination. Such fine particles can be synthesized using, for example, a method of emulsion polymerization of a hydrophobic monomer in the presence of a polyamine. As a specific method, for example, in an aqueous solution or a mixed solution of water and a hydrophilic solvent, an amino group-containing polymer, a peroxide, and a radically polymerizable hydrophobic monomer containing no amino group are allowed to coexist and heated. A method is mentioned. Thereby, a peroxide reacts with an amino group to generate a radical, and a radical reaction using an amine radical as an initiator proceeds. At this time, the amino group-containing polymer is present in the shell portion in a large amount due to its strong hydrophilicity, and the polymer formed by radical polymerization is present in the core portion because it is hydrophobic. As a result, core-shell particles having a uniform particle size can be synthesized without using an emulsifier.

  As the amino group-containing polymer in this reaction, a polyamine having a primary amino group can be particularly preferably used because of its high reactivity with peroxides and good conversion rate of radical reaction. Of these, polyethyleneimine having a branched structure, polyallylamine, and the like are most preferable because they are easily available.

  In the alternate lamination method of Patent Document 3 and Non-Patent Document 7 described above, hydrophilic polymer and amino group are introduced onto the surface by physical adsorption as described above. It only adheres in the form of a thin film on the surface of the fine particles serving as the core, and does not have a uniform spatial extent by solvating in the aqueous medium. Therefore, it is not easy to combine such a physically adsorbed hydrophilic polymer with a metal oxide in the nanometer order. Therefore, even if the obtained composite is baked, the polymer-derived carbon and the metal oxide It is not possible to form a shell made of a complex with. On the other hand, the monodisperse polymer fine particles (X) used as a template in the present invention have a spatial extent of the hydrophilic polymer layer (x1) in an aqueous medium, so that the concentration / sol-gel reaction of the metal alkoxide (Y) is performed. -The composite with the metal oxide (Y ') is easy, and after firing, the composite with the metal oxide (Y') and carbon is easy, and the metal oxide (Y ' Even after the metal oxide coating layer formed by combining ') and the hydrophilic polymer layer (x1) is formed, a part of the hydrophilic polymer layer exists on the outermost surface. This is different from the known literature in that it has a special form in which carbon is also present on the surface.

[Metal alkoxide (Y) and metal oxide (Y ′)]
In the first step of the production method of the present invention, a solution of metal alkoxide (Y) is mixed with the aqueous dispersion of monodisperse polymer fine particles (X) described above, and the sol-gel reaction of metal alkoxide (Y) is monodispersed. This is performed on the surface of the polymer fine particles (X), and a film made of the metal oxide (Y ′) is formed on the monodisperse polymer fine particles (X).

The metal alkoxide (Y) is represented by M- (OR) _n , M is a metal, -OR is an alkoxide group (O is oxygen, R is an alkyl group). n represents the valence of the metal M. The sol-gel reaction (hydrolysis / condensation reaction) of such metal alkoxide (Y) forms a film consisting of a network of metal oxides (Y ′). From the point of obtaining a strong film, hydrolysis It is preferable to use a metal alkoxide having a trivalent or higher alkoxide group. In particular, when a tetravalent or higher-valent metal alkoxide such as tetraalkoxysilane is used, it is preferable because the hardness of the film formed on the monodisperse polymer fine particles (X) can be increased. When using a metal alkoxide having a large number of functional groups for the purpose of increasing the hardness, the content of tetravalent or higher metal alkoxide in the total metal alkoxide (Y) is preferably 30% by mass or more, and 50% by mass. More preferably.

  Examples of the metal species M of the metal alkoxide (Y) include silicon, titanium, zirconium, aluminum, boron, germanium, zinc, etc. Among these, sol-gel reaction is easy, and silicon, titanium, zirconium Aluminum is preferable, and silicon is particularly preferable from the viewpoint of industrial availability.

  Examples of the metal alkoxide having silicon as the metal species M include alkoxysilane which may have a reactive functional group. In the present invention, unless otherwise specified, alkoxysilanes include those oligomerized by a hydrolysis reaction. The oligomerized product may be used in a silica sol state converted to silanol. As the oligomerized alkoxysilane, those having an average degree of polymerization of 2 to 20 can be suitably used.

  Examples of the alkoxysilane include dialkoxysilanes such as dimethyldimethoxysilane, diethyldimethoxysilane, methylethyldimethoxysilane, diphenyldimethoxysilane, and phenylmethyldimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, Trialkoxy such as phenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloylpropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane Silane, tetramethoxysilane, tetraethoxysilane, tetra (2-ethanol) orthosilicate, tetra (n-propoxy) silane, tetra (isopropyl) Epoxy) tetraalkoxysilane such as silane.

  Furthermore, examples of the alkoxysilane having a functional group include chlorosilanes such as tetrachlorosilane and methyltrichlorosilane as halogen-containing silanes.

  Examples of the metal alkoxide having titanium as a metal species include alkoxytitanium such as tetraisopropoxytitanium, tetraethoxytitanium, tetrabutoxytitanium, and tetrapropoxytitanium, and titanium acetylacetonate, titanium octylene glycol, and titanium. Various titanium chelates prepared from metal alkoxides of titanium, such as tetraacetylacetonate, titanium ethyl acetate, titanium diisopropoxybis (triethanolaminate), titanium lactate ammonium salt, titanium lactate and the like may be used. Examples of the metal alkoxide having aluminum as a metal species include alkoxyaluminum such as triethoxyaluminum.

  Examples of the metal alkoxide having zirconium as a metal species include tetramethoxyzirconium, tetraethoxyzirconium, tetrabutoxyzirconium, tetraisopropoxyzirconium, tetrapropoxyzirconium, tetra-sec-butoxyzirconium, and tetra-t-butoxyzirconium. Alkoxyzirconium zirconium, zirconium tributoxy monoacetyl acetonate, zirconium monobutoxy acetyl acetonate bis (ethyl acetoacetate), zirconium dibutoxy bis (ethyl acetoacetate), zirconium tetraacetyl aceto , Zirconium tributoxy monostearate, zirconium chloride compound Bon acid, may be used various zirconium chelate prepared from zirconium metal alkoxide.

  These metal alkoxides (Y) may be used singly or in combination of two or more, but when alkoxysilane and alkoxides of other metals such as titanium, zirconium and aluminum are used in combination In order to prevent the metal oxide formed on the template fine particles from becoming non-uniform due to the difference in reaction rate, it is preferable to use the alkoxide ratio of these other metals with respect to the alkoxysilane to 30% by mass or less. .

  These metal alkoxides (Y) are mixed with an aqueous medium in which the monodisperse polymer fine particles (X) are dispersed in a solution state. In the mixed solution, the metal alkoxide (Y) is hydrolyzed. An M-OH structure is generated and concentrated in the hydrophilic polymer layer (x1) existing on the surface of the monodisperse polymer fine particles (X). Here, the amino group (x2) and further the carboxy group (x3) present on the surface of the monodisperse polymer fine particles (X) serve as a catalyst for promoting the hydrolysis and condensation reaction of the metal alkoxide (Y), and are a metal efficiently. An oxide (Y ′) is formed. This metal oxide (Y ′) is formed by hydrogen bonding with the hydrophilic polymer layer (x1), and when the hydrophilic polymer has a hydroxy group, further causes a dehydration condensation reaction, whereby the surface of the fine particles and the metal oxide ( A covalent bond is formed during Y ′) to form a strongly bonded coating layer. By this mechanism, the hydrolysis / condensation reaction of the metal alkoxide (Y) proceeds almost selectively on the monodisperse polymer fine particles (X).

  As the solvent for dissolving the metal alkoxide (Y), a solvent that is soluble in the metal alkoxide (Y) and can be mixed with an aqueous medium in which the monodisperse polymer fine particles (X) are dispersed can be used. For ease of use, alcohols such as methanol, ethanol and 2-propanol, acetone and the like can be used alone or in admixture of two or more. Moreover, these solvents and water may be mixed. At this time, when the metal alkoxide (Y) is a metal alkoxide such as titanium, zirconium or aluminum which is not chelated alone, rapid hydrolysis and condensation reaction occur, and the monodisperse polymer fine particles (X) In addition, there is a possibility of forming a metal oxide alone in the solution or causing aggregation of the fine particles, and in order to prevent this, it is preferable to use alcohols not mixed with water. On the other hand, when the metal alkoxide (Y) is a chelated water-soluble compound, for example, titanium diisopropoxybis (triethanolaminate), titanium lactate ammonium salt, titanium lactate, dihydroxybis (hydroxycarboxylate) Titanium, titanium peroxocitrate ammonium, zirconium chloride compound aminocarboxylic acid and the like can use water alone as a solvent.

  These metal alkoxide (Y) solutions can be appropriately selected from 10 to 90% by mass, but if the concentration is too low, it takes time to form a film (sol-gel reaction), while the concentration is too high. It is more preferable to use those having a concentration of 30 to 70% by mass because of the high possibility of causing aggregation of fine particles.

  In the present invention, as the aqueous medium in which the monodisperse polymer fine particles (X) are dispersed, as described above, water is used alone, lower alcohol such as methanol, ethanol, isopropanol, etc., ethylene glycol, propylene glycol, Examples thereof include polyhydric alcohols such as butanediol, diethylene glycol, and triethylene glycol; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran. X) The metal alkoxide (Y) used for the purpose of forming a film of the metal oxide (Y ′) on the metal alkoxide alone such as titanium, zirconium, aluminum, etc. that is not chelated is in solution. Formed metal oxide alone In order to prevent this, the water content is 5% by mass or less, more preferably, the water content is 1% by mass or less. preferable.

  If the concentration of the dispersion liquid of the monodisperse polymer fine particles (X) is too high, aggregation between the fine particles is likely to occur. If the concentration is too low, it takes time to form a film. It is more preferable to use 2-20% by mass.

  Further, in order to form a metal oxide (Y ′) film on the monodisperse polymer fine particles (X), a dispersion of the monodisperse polymer fine particles (X) and a solution of the metal alkoxide (Y) are mixed, The stirring time is preferably 5 to 180 minutes. In a short time of 5 minutes or less, the formed film made of the metal oxide (Y ′) is too thin and may be collapsed by a subsequent baking process. As the stirring time becomes longer, the condensation reaction proceeds and the film made of the metal oxide (Y ′) on the monodisperse polymer fine particles (X) also becomes thicker, forming a stronger film. Longer time is better. However, since the increase in film thickness is almost saturated in about 90 minutes, stirring may be performed for about 90 to 180 minutes.

  The film thickness of the metal oxide (Y ′) formed on the monodisperse polymer fine particles (X) can be 5 nm to 30 nm depending on the purpose, but it has sufficient strength after the firing step. In order to maintain a hollow particle structure, it is more preferable to prepare a 10-30 nm thing. From the point that such a film thickness can be obtained easily, mixing is performed so that the mass ratio (as an active ingredient) of the monodisperse polymer fine particles (X) and the metal alkoxide (Y) is 5: 1 to 1: 5. It is preferable.

  The monodisperse polymer fine particles (X) coated with a coating made of a metal oxide (Y ′) are subjected to a firing process after removing the solvent by operations such as filtration, centrifugation, lyophilization, and evaporator. .

[Baking process]
As described above, the second step in the production of the carbon-containing metal oxide hollow particles of the present invention is to form the metal oxide (Y ′) film on the monodisperse polymer fine particles (X), and then calcinate it. In this step, a part of the polymer fine particles (X) is carbonized to be carbonized to form a composite with a metal oxide (Y ′) coating.

  The content of carbon to be complexed with the metal oxide (Y ′) can be adjusted by selecting the firing temperature, so that a coating made of the metal oxide (Y ′) is formed on the monodisperse polymer fine particles (X). Carbon-containing metal oxide hollow particles exhibiting different color development can be obtained from the same formed particles.

  The firing temperature can be appropriately selected from a temperature range of 250 to 1300 ° C. depending on the type and purpose of the monodisperse polymer fine particles (X) and metal alkoxides (Y) used as raw materials, and the monodisperse polymer fine particles (X) and metal Firing may be performed under conditions where the organic component derived from the alkoxide (Y) does not completely decompose and disappear. Conditions under which the organic component is not completely decomposed and lost can be set by measuring the thermal decomposition behavior in advance using, for example, thermogravimetric analysis.

  Furthermore, the organic component in the monodisperse polymer fine particle (X) -metal oxide (Y ′) composite is efficiently carbonized by changing the firing atmosphere from the presence of air to under nitrogen, under argon, or the like. Also, a method of combining the metal oxide (Y ′) and carbon is effective. Depending on the purpose, the atmosphere may be changed by completely exchanging the atmosphere before heating and baking, or by changing the atmosphere in the heating stage.

  For the firing, a microwave oven or a spray dryer can be used in addition to various known firing furnaces such as a muffle furnace, an atmospheric furnace, and an infrared furnace.

[Carbon-containing metal oxide hollow particles]
The carbon-containing metal oxide hollow particles of the present invention are obtained by the above-described process, and the thickness of the shell wall containing the metal oxide (Y ′) and carbon as main constituent components is 5 nm to 5 nm depending on the purpose. Although 30 nm and an average particle diameter of 50 nm to 1000 nm can be prepared, the partition wall thickness is 10 nm to 30 nm because it has sufficient strength to maintain the hollow structure and has good color development. Further, those having an average particle diameter of 150 nm to 500 nm are more preferable. Further, as the metal oxide (Y ′), silica is preferable because of its high versatility. In the present invention, when the metal oxide (Y ′) and carbon are the main constituent components, the components other than the carbon derived from the monodisperse polymer fine particles may be slightly contained due to the poor firing conditions. As long as other components are not intentionally used, it indicates that the shell is formed of a metal oxide (Y ′) and carbon.

  The mass ratio of carbon in the shell is 1 to 80% by mass, and has an excellent balance between the point of effectively having color developability other than white and the strength of the carbon-containing metal oxide hollow particles. It is preferable that it is 5-70 mass%. This mass ratio can be adjusted in the firing process by setting the firing temperature and firing atmosphere. The conditions under which the organic component is converted into carbon and completely compounded in the shell without completely decomposing and disappearing can be set by measuring the thermal decomposition behavior in advance using, for example, thermogravimetric analysis.

  The form of the carbon-containing metal oxide hollow particles of the present invention is basically spherical, but may be a form in which a part of the surface is recessed.

  The method of using the carbon-containing metal oxide hollow particles of the present invention is not particularly limited. For example, in the field of coatings and paints, the unique light scattering characteristics and color developability due to internal pores are utilized. As a colorant, light scattering agent, light scattering aid for imparting performance such as bright coloring, gloss, opacity, etc. to paper, fiber, leather, etc., and light diffusibility, water absorption, oil absorption by hollow structure It can be applied to cosmetics utilizing the properties, and can also be used as an ink jet receiving layer. Furthermore, since the heat conduction and sound conduction can be suppressed due to the hollow structure, it can be applied as a heat insulating material or a sound insulation material, and the mass in the same volume can be reduced, so that it can be used as a lightening agent. Furthermore, it can be used as a chemical substance holding agent containing various chemical substances inside, and can also be used as a chemical substance sustained release agent and a DDS material. In addition, since it has a hollow structure in which carbon is compounded, it has excellent substance adsorbing power and can be used as various adsorbents. Further, hollow particles of metal oxides such as silica, titanium oxide, zirconium oxide, etc. Since it is excellent in structural stability and chemical stability, it is particularly useful industrially and is expected to be applied as a catalyst utilizing a large surface area based on a hollow structure or a catalyst support. For use in such applications, the monodispersed carbon-containing metal oxide hollow particles of the present invention are effective for efficiently and uniformly expressing various performances required for the application. Therefore, its usefulness is high.

  Next, in order to describe the present invention in more detail, examples and comparative examples will be given, but it is needless to say that the present invention is not limited by these descriptions. Hereinafter, in the examples, the monodisperse polymer fine particles (X) capable of performing the sol-gel reaction of the metal alkoxide on the surface thereof may be referred to as template particles.

Confirmation of the hydrophilic polymer layer solvated in the aqueous medium was performed by measuring a ¹ H-NMR spectrum using JNM-LA300 manufactured by JEOL Ltd. The particle size of the particles dispersed in water was measured by a dynamic light scattering method using a particle size measuring device FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. For measurement of the surface potential of the particles in the water dispersion state, a zeta potential / particle size measurement system ELS-Z2 manufactured by Otsuka Electronics Co., Ltd. was used.

  To confirm the shape and hollowness of the fine particles, SEM observation was performed using a 3D real surface view microscope VE-9800 manufactured by Keyence Corporation. The thickness of the shell of the hollow particles was determined by the transmission electron microscope JEM manufactured by JEOL Ltd. The particle structure was observed using -2200FS, the thickness of the shell portion was estimated from the observed image, and the average value of 30 measured values was taken as the shell thickness. The carbon in the carbon-containing metal oxide hollow particles was confirmed using a high resolution transmission electron microscope JEM-2010MX manufactured by JEOL Ltd. The amount of the metal oxide formed on the monodisperse polymer fine particles and the amount of carbon in the carbon-containing metal oxide hollow particles were manufactured by SII NanoTechnology Co., Ltd., differential thermal thermogravimetric simultaneous measurement device (EXSTAR6000 TG). / DTA).

  The presence of carbon complexed with the metal oxide in the shell constituting the hollow particles was confirmed using a Raman laser microscope manufactured by Renishaw. The reflection spectrum for confirming the color developability of the carbon-containing metal oxide hollow particles was measured using a USB-4000 spectrometer manufactured by Ocean Photonics.

[Synthesis example of monodisperse polymer fine particles]
Synthesis Example 1 (Synthesis of monodisperse polymer fine particles having a hydrophilic polymer layer on the surface)
12 g of glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 300 ml of an aqueous solution in which 2 g of N-isopropylacrylamide (manufactured by Kojin Co., Ltd.) is dissolved, and 2,2 ′ is used as an amino group-containing water-soluble polymerization initiator. -After dissolving 0.15 g of azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.), the mixture was stirred while flowing nitrogen to remove oxygen in the system. This liquid was stirred at 65 ° C. and a stirring speed of 100 rpm for 1 hour to obtain a dispersion liquid of monodisperse hollow polymer particles. After the dispersion was washed by a centrifugal separation operation, the shape of the fine particles was observed with an SEM. When this particle was dispersed in heavy water and measured by ¹ H-NMR, only a signal derived from poly (N-isopropylacrylamide) was observed (FIG. 2). It was confirmed that a hydrophilic polymer layer was present and the hydrophilic polymer layer was solvated in the solvent. The thickness of the hydrophilic polymer layer is considered to be about 20 nm from the difference in average particle diameter determined by the dynamic light scattering method at 25 ° C. and 50 ° C. (template particle A).

Synthesis Examples 2-7
By carrying out the reaction under the same conditions as in Synthesis Example 1 except that the stirring speed was changed, a dispersion liquid of monodisperse hollow polymer particles having the particle diameters shown in Table 1 was obtained. When this particle was dispersed in heavy water and measured by ¹ H-NMR, only a signal derived from poly (N-isopropylacrylamide) was observed, and the monodisperse hollow polymer particle had a hydrophilic polymer layer on its outer side. It was confirmed that the hydrophilic polymer layer was solvated in the solvent.

(Introduction of amino group)
Amino group introduction example 1
To 100 ml of a 3% by mass aqueous solution of monodisperse polymer particles B having a hydrophilic polymer layer on the surface synthesized by the method of Synthesis Example 2, 100 ml of a 1% by mass aqueous solution of polyethyleneimine (manufactured by Nippon Shokubai, Epomin SP-200) is added. After stirring for 3 days, washing was carried out by dialysis and centrifugation to obtain amine-modified template particles in which polyethyleneimine was bonded to the surface of monodisperse particles. When the particles were dispersed in heavy water and measured by ¹ H-NMR, a signal derived from polyethyleneimine was observed in the vicinity of 2-3 ppm in addition to a signal derived from poly (N-isopropylacrylamide) (FIG. 3). ), It was confirmed that polyethyleneimine was introduced to the surface of the polymer particles, and the polyethyleneimine layer was dissolved in the solvent. The thickness of the polyethyleneimine layer was about 30 nm from the difference in average particle diameter determined by the dynamic light scattering method before and after the introduction of polyethyleneimine (amino group-modified template particle 1). The above epomin is a registered trademark of Nippon Shokubai Co., Ltd. The same applies to the following description.

Amino group introduction examples 2 to 4
In the same manner as in Introduction Example 1, 100 parts by mass of an aqueous solution containing 0.5% by mass of an amino group-containing compound shown in the following table was added to 100 parts by mass of a 3% by mass aqueous solution of monodisperse polymer fine particles having a hydrophilic polymer layer on the surface. After stirring, washing was performed by dialysis and centrifugal separation to obtain amino group-modified template particles having an amino group-containing compound introduced on the surface of monodisperse polymer fine particles. The introduction of amino groups was confirmed by an increase in the amount of nitrogen in the particle composition by elemental analysis of the particles before and after the reaction. Table 2 summarizes the amino group-containing molecules used for the surface modification and the increased amount of amino groups after the modification.

The following abbreviations are used for the amino group-introduced molecules used in this example.
Polyethyleneimine: PEI
2-aminoethanethiol: AET
L-cysteine: Cys
L-alanine: Ala
L-serine: Ser
L-leucine: Leu
L-lysine: Lys
Glycine: Gly

Amino group introduction examples 5 to 11
In the same manner as in Introduction Example 1, amino group-containing compounds shown in Table 3 were introduced on the surface of monodisperse polymer fine particles to obtain amino group-modified template particles. The introduction of the amino group-containing compound was confirmed by changing the zeta potential of the template particles before and after the reaction.

Synthesis example 8
12 g of glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 300 ml of an aqueous solution in which 2 g of N-isopropylacrylamide (manufactured by Kojin Co., Ltd.) is dissolved, and potassium persulfate (Wako Pure Chemical Industries, Ltd.) is used as a water-soluble polymerization initiator. After dissolving 0.15 g (manufactured by Kogyo Co., Ltd.), the mixture was stirred while flowing nitrogen to remove oxygen in the system. This liquid was stirred at 65 ° C. for 1 hour to obtain a dispersion of hollow polymer particles. After the dispersion was washed by a centrifugal separation operation, the shape of the fine particles was observed with an SEM. As a result, the particles were monodisperse spherical particles having an average particle diameter of 300 nm. When this particle was dispersed in heavy water and measured by ¹ H-NMR, only a signal derived from poly (N-isopropylacrylamide) was observed, and a hydrophilic polymer layer was present outside the hollow polymer particle, It was confirmed that the hydrophilic polymer layer was dissolved in the solvent. The thickness of the hydrophilic polymer layer was about 5 nm from the difference in average particle diameter determined by the dynamic light scattering method at 25 ° C. and 50 ° C.

Amino group introduction example 12
To 100 ml of a 3% by weight aqueous solution of monodisperse hollow polymer particles having a hydrophilic polymer layer on the surface synthesized by the method of Synthesis Example 8, 100 ml of a 1% by weight aqueous solution of polyethyleneimine (manufactured by Nippon Shokubai, Epomin SP-200) is added. After stirring for 3 days, washing was carried out by dialysis and centrifugation to obtain template particles 12 in which polyethyleneimine was bonded to the surface of monodisperse particles. When the particles were dispersed in heavy water and subjected to ¹ H-NMR measurement, in addition to the signal derived from poly (N-isopropylacrylamide), a signal derived from polyethyleneimine was observed in the vicinity of 2-3 ppm. It was confirmed that polyethyleneimine was introduced into the polyethyleneimine layer and the polyethyleneimine layer was solvated in the solvent. The thickness of the polyethyleneimine layer was about 20 nm from the difference in average particle diameter determined by the dynamic light scattering method before and after the introduction of polyethyleneimine.

Synthesis Example 9
9.4 g of glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) is added to 300 ml of an aqueous solution in which 1.3 g of N, N-dimethylacrylamide (manufactured by Kojin Co., Ltd.) is dissolved. , 2′-Azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) (0.1 g) was dissolved and then stirred while flowing nitrogen to remove oxygen in the system. This liquid was stirred at 65 ° C. for 1 hour to obtain a dispersion of template particles 13. After the dispersion was washed by a centrifugal separation operation, the shape of the particles was observed by SEM. As a result, the particles were monodisperse spherical particles having an average particle diameter of 250 nm. When the particles were dispersed in heavy water and subjected to ¹ H-NMR measurement, only a signal derived from poly (N, N-dimethylacrylamide) was observed, and a hydrophilic polymer layer was present outside the particles. It was confirmed that the hydrophilic polymer layer was solvated in the solvent. The thickness of the hydrophilic polymer layer was about 50 nm from the difference between the average particle size obtained by the dry state and the dynamic light scattering method.

Synthesis Example 10
2.6 g of N-isopropylacrylamide and 16 g of styrene were added to 200 ml of water, and 2,2′-azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) 0 under a nitrogen stream at 70 ° C. 20 ml of water in which 25 g was dissolved was added and polymerized for 17 hours with stirring to obtain a dispersion of particles 14. After the dispersion was washed by centrifugation, the shape of the particles was observed by SEM. As a result, the particles were monodisperse spherical particles having an average particle diameter of 270 nm. At 25 ° C. and 50 ° C., there was no difference in the average particle size determined by the dynamic light scattering method, and the presence of a hydrated hydrophilic layer could not be confirmed on the particle surface.

Synthesis Example 11
To 100 ml of a 3.6% by mass aqueous solution of particles 14 made of a copolymer of N-isopropylacrylamide and styrene obtained in Synthesis Example 10, 0.8 g of N-isopropylacrylamide, N, N′-methylenebisacrylamide 0 40 ml of water in which 0.08 g was dissolved was added, and 10 ml of water in which 0.08 g of 2,2′-azobis (2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in a nitrogen stream at 70 ° C. In addition, polymerization was performed for 4 hours with stirring to obtain a dispersion of core-shell type template particles 15 having a cross-linked poly N-isopropylacrylamide shell layer on the surface of the particles 14. When the shape of this particle was observed with an SEM, it was a monodispersed true spherical particle having an average particle diameter of 270 nm which was the same as that of the core particle (particle 14) in a dry state. The thickness of the hydrophilic polymer layer on the surface of the template particles dissolved in the solvent was about 15 nm from the difference in average particle diameter determined by the dynamic light scattering method at 25 ° C. and 50 ° C.

Synthesis Example 12
In 200 ml of water, 2.6 g of N-isopropylacrylamide and 16 g of styrene are added, and 20 ml of water in which 0.25 g of potassium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved at 70 ° C. in a nitrogen stream is stirred. Then, polymerization was carried out for 17 hours to obtain a dispersion of particles 16. After the dispersion was washed by centrifugation, the shape of the particles was observed with an SEM. As a result, the particles were monodisperse spherical particles having an average particle diameter of 280 nm. At 25 ° C. and 50 ° C., there was no difference in the average particle size determined by the dynamic light scattering method, and the presence of a hydrophilic layer hydrated on the particle surface could not be confirmed.

Synthesis Example 13
Water was removed from polyethyleneimine (manufactured by Across, Mw 60,000, 50 wt% aqueous solution), and then dissolved in 30 ml of chloroform. To this solution, 0.28 g of glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for 1 hour, 100 ml of water was added, and chloroform was removed by an evaporator. Further, 300 ml of water was added, and the pH of the solution was adjusted to 7 with hydrochloric acid. 16 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to this solution and stirred for 30 minutes under a nitrogen stream. Thereafter, 20 ml of an aqueous solution in which 9 mg of t-butyl hydroperoxide (manufactured by Aldrich, 70 wt% aqueous solution) is dissolved, and stirred for 2 hours (300 rpm) at 80 ° C., so that a polymethyl methacrylate core and a polyethyleneimine shell layer are obtained. A dispersion of the core-shell type template particles 17 having the following was obtained. After the dispersion was washed by centrifugation, the shape of the particles was observed with an SEM. As a result, the particles were monodisperse spherical particles having an average particle size of 170 nm (FIG. 4). When this particle was dispersed in heavy water and measured by ¹ H-NMR, only a signal derived from polyethyleneimine was observed (FIG. 5), and a hydrophilic polymer layer was present on the template particle. It was confirmed that the layer was solvated in the solvent. The thickness of the hydrophilic polymer layer was about 70 nm from the difference between the average particle size obtained by the dry state and the dynamic light scattering method.

Example 1 and Reference Example 1 (Formation of metal oxide film on template particles)
100 mass parts of a 5 mass% aqueous dispersion of monodisperse polymer fine particles having a hydrophilic polymer layer solvated in an aqueous medium and amino groups on the surface, prepared according to the above synthesis example and amino group introduction example, and a silica source As a result, 12.5 parts by mass of a 50% by mass ethanol solution of MS-51 (manufactured by Colcoat Co., Ltd.) was mixed and stirred for 3 hours to form a metal oxide film on the template particles. Thereafter, the composite particles are washed by centrifugal separation, dried, and then dried for 30 minutes at 500 ° C. in the presence of air using an electric furnace, so that the carbon-containing metal oxide hollow particles exhibit vivid color development. Got. Silica amount compounded on template particles (= silica layer mass / silica layer composite template particle mass), silica layer thickness of hollow particles obtained after firing, composite carbon amount of carbon-containing metal oxide hollow particles ( = Carbon mass / carbon composite silica hollow particle mass) and color development are summarized in Table 4.
In Table 4, an example in which the amino group-derived compound column is “cysteine (Cys)” is an example of the present invention. That is, template particles 4 and 6 are examples of the present invention, and other template particles (A, B, 1, 2, 3, and 5) are reference examples.

When the Raman spectrum of the obtained carbon-containing metal oxide hollow particles was measured, a peak derived from carbon appeared (in the vicinity of 1354, 1548 cm ⁻¹ ), and the presence of complexed carbon could be confirmed .

Example 2 and Reference Example 2
Same as Example 1 except that the mixing time of the template particles and the ethanol solution of the silica source was changed from 3 hours to 10, 30, 60, 90 minutes in the step of forming the metal oxide film on the template particles. Thus, carbon-containing metal oxide hollow particles composed of a shell wall in which silica and carbon were combined were obtained. Silica amount compounded on template particles (= silica layer mass / silica layer composite template particle mass), silica layer film thickness of hollow particles obtained after firing, and composite carbon amount in carbon composite silica hollow particles Table 5 summarizes the color development (= carbon mass / carbon composite silica hollow particle mass).
In Table 5, the column in which the amino group-derived compound column is “cysteine (Cys)” is an example of the present invention. That is, the template particle 4 is an example of the present invention, and the other template particles (A and 3) are reference examples.

When the Raman spectrum of the obtained hollow particles was measured, a peak derived from carbon appeared (in the vicinity of 1354, 1548 cm −1), and the presence of complexed carbon was confirmed. It was confirmed by SEM observation that these particles were monodispersed and spherical, and the contents were hollow .

Example 3 and Reference Example 3
In the step of forming the metal oxide film on the template particles, the addition amount of the ethanol solution of the silica source mixed with 100 parts by mass of the 5% aqueous dispersion of the template particles is changed from 12.5 parts by mass to 6.25 parts by mass. Except for changing to 25 parts by mass and 37.5 parts by mass, the same operation as in Example 1 was performed to obtain carbon-containing metal oxide hollow particles composed of a shell wall in which silica and carbon were combined. Silica amount compounded on template particles (= silica layer mass / silica layer composite template particle mass), silica layer film thickness of hollow particles obtained after firing, and composite carbon amount in carbon composite silica hollow particles (= Carbon mass / carbon composite silica hollow particle mass) and color development are summarized in Table 6.
In Table 6, those in which the amino group-derived compound column is “cysteine (Cys)” are examples of the present invention. That is, the template particle 6 is an example of the present invention, and the other template particles (B and 5) are reference examples.

Example 4 and Reference Example 4
Except that the atmosphere during firing was changed from the presence of air to a nitrogen atmosphere, in the same manner as in Example 1, carbon-containing metal oxide hollow particles composed of a shell wall in which silica and carbon were combined were obtained. . Table 7 summarizes the silica layer thickness of the hollow particles obtained after firing, the amount of composite carbon in the carbon composite silica hollow particles (= carbon mass / carbon composite silica hollow particle mass), and color development.
In Table 7, the amino group-derived compound column is “cysteine (Cys)” is an example of the present invention. That is, template particles 4 and 6 are examples of the present invention, and other template particles (B, D, 3 and 5) are reference examples.

When the Raman spectrum of the obtained silica hollow particles was measured, a peak derived from carbon appeared (in the vicinity of 1354, 1548 cm ⁻¹ ), and the presence of complexed carbon was confirmed. It was confirmed by SEM observation that these particles were monodispersed and spherical, and the contents were hollow .

Example 5 and Reference Example 5
Shell wall in which silica and carbon are combined in the same manner as in Example 1 except that the atmosphere during firing is changed from the presence of air to a nitrogen atmosphere and the firing temperature is changed from 500 ° C. to 800 ° C. A carbon-containing metal oxide hollow particle comprising the following was obtained. Table 8 summarizes the color development, the amount of composite carbon in the hollow particles, and the shell thickness of the obtained carbon-containing metal oxide hollow particles.
In Table 8, an example in which the amino group-derived compound column is “cysteine (Cys)” is an example of the present invention. That is, the template particle 6 is an example of the present invention, and the other template particles (B and D) are reference examples.

When the Raman spectrum of the obtained carbon-containing metal oxide hollow particles was measured, a peak derived from carbon appeared (in the vicinity of 1354, 1548 cm ⁻¹ ), and the presence of complexed carbon could be confirmed. These particles were monodispersed and spherical in shape by SEM observation, and from the form of some broken particles, it was confirmed that the contents were hollow particles. From the visible light reflection spectrum measurement of the hollow particles produced using the particles 6, the firing temperature and the firing atmosphere were changed from the presence of air to nitrogen (produced using the particles 6 in Examples 1, 4 and 5). The reflection spectrum of the hollow particles is shown as an example), and it was confirmed that even the fired product of the same silica-template particles showed different color development (FIG. 12).

Example 6 (Formation of metal oxide coating on template particles)
100 mass parts of a 3% aqueous dispersion of monodisperse polymer fine particles having a hydrophilic polymer layer solvated in an aqueous medium, an amino group, and a carboxyl group on the surface, prepared according to Synthesis Example 1, and a silica source A metal oxide film was formed on the template particles by mixing 7.3 parts by mass of a 50% by mass ethanol solution of MS-51 and stirring for 3 hours. Thereafter, the combined particles were washed by centrifugation. After drying, by firing for 30 minutes at 500 ° C. in the presence of air using an electric furnace, spherical hollow particles composed of a shell wall in which silica and carbon were combined were obtained. Silica amount (= silica layer mass / silica layer composite template particle mass), silica layer thickness of the hollow particles obtained after firing, composite carbon amount in carbon composite silica hollow particles (= carbon mass / carbon composite) The mass of silica hollow particles) and color development are summarized in Table 9.

When the Raman spectrum of the obtained carbon-containing metal oxide hollow particles was measured, a peak derived from carbon appeared (in the vicinity of 1354, 1548 cm ⁻¹ ), and the presence of complexed carbon could be confirmed. These particles were monodispersed and spherical in shape by SEM observation, and from the form of some broken particles, it was confirmed that the contents were hollow particles.

Example 7 (Formation of metal oxide film on template particles)
Similar to Example 6 except that a 1: 1 mixture of MS-51 and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) was used as the silica source instead of MS-51. Thus, carbon-containing metal oxide hollow particles were produced. Table 10 shows silica composited on the template particles (= silica layer mass / silica layer composite template particle mass), the silica layer thickness of the hollow particles obtained after firing, and the carbon composite silica hollow particles. The composite carbon amount (= carbon mass / carbon composite silica hollow particle mass) and color development were summarized.
In Table 10, those in which the amino group-derived compound column is “Ala, Ser, Leu, Lys, and Gly)” are examples of the present invention. That is, template particles 7 to 11 are examples of the present invention, and other template particles (D) are reference examples.

Comparative Example 1
As a template particle, the same operation as in Example 1 was carried out except that the polymer particle having no amino group on the surface produced in Synthesis Example 8 was used. Could not get.

Reference Example 6
Except that the template particles 12 produced in the amino group introduction example 12 were used as template particles, the same operation as in Example 1 was performed to obtain hollow particles composed of a shell wall in which silica and carbon were combined. The amount of silica complexed on the template particles was 11.2%. The carbon composite silica hollow particles showed yellowish green, the average shell thickness was 8 nm, and the composite carbon content was 20.4%.

Reference Example 7
Except for using the particles 13 synthesized in Synthesis Example 9 as template particles, the same operation as in Example 1 was performed to obtain hollow particles composed of a shell wall in which silica and carbon were combined. The amount of silica complexed on the template particles was 3.5%. The carbon-containing metal oxide hollow particles had a deep purple color, an average shell thickness of 5 nm, and a composite carbon content of 51.2%.

Comparative Example 2
Example 1 except that monodisperse polymer fine particles 14 having no amino group of an initiator residue on the surface and having a hydrophilic polymer layer solvated in an aqueous medium prepared according to Synthesis Example 10 are used as template particles. The same operation was performed to obtain silica hollow particles. The amount of silica complexed on the template particles was 15.5%. The hollow particles were not colored and were white, and the presence of carbon could not be confirmed even by measuring the Raman scattering spectrum.

Reference Example 8
Except for using monodisperse polymer fine particles 15 having a hydrophilic polymer shell layer on the surface and having an amino group of an initiator residue on the surface, prepared according to Synthesis Example 11, the same as in Example 1 As a result, dark purple hollow particles composed of a shell wall in which silica and carbon were combined were obtained. The carbon-containing metal oxide hollow particles had an average shell thickness of 12 nm and a composite carbon content of 41.4%.

Comparative Example 3
As a template particle, the same operation as in Example 1 was performed except that the polymer particle 16 having no amino group on the surface prepared in Synthesis Example 12 was used. As a result, the particle disappeared completely by firing at 500 ° C. Hollow particles could not be obtained.

Reference Example 9 (Formation of metal oxide film on template particles)
A dark brown color composed of a shell wall in which silica and carbon are combined in the same manner as in Example 1 except that the monodisperse polymer fine particles 17 having a polyethyleneimine layer on the surface produced according to Synthesis Example 13 were used. The carbon-containing metal oxide hollow particles were obtained. The amount of silica complexed on the template particles was 30.7%. The hollow shell had an average shell thickness of 25 nm and a composite carbon content of 1.1%.

Reference Example 10 (Formation of metal oxide film on template particles)
100 parts by mass of an 8% aqueous dispersion of monodisperse polymer fine particles having a polyethyleneimine layer on the surface, prepared according to Synthesis Example 1 and amino group introduction example 1, and titanium (IV) bis (ammonium as a titanium oxide source Lactate) After mixing with 100 parts by mass of a 25% by mass aqueous solution of dihydroxide (manufactured by Aldrich) and stirring for 30 minutes, a metal oxide film was formed on the template particles, and then composited by centrifugation. The particles were washed. The amount of titanium oxide complexed on the template particles was 2.7%.

(Production of metal oxide hollow particles by firing)
After drying the polymer template fine particles with titanium composited on the surface, it is baked for 30 minutes at 500 ° C. in the presence of air using an electric furnace, so that the light blue color of the shell wall composed of titanium oxide and carbon composited Hollow particles were obtained. The carbon composite titanium oxide hollow particles had an average shell thickness of 5 nm and a composite carbon content of 3.1%. Further, from the Raman spectrum, it was confirmed that this titanium oxide was an anatase type crystal.

2 is an SEM observation image of monodisperse polymer fine particles obtained in Synthesis Example 1. 2 is a ¹ H-NMR spectrum measured by dispersing the monodisperse polymer fine particles obtained in Synthesis Example 1 in heavy water. 2 is a ¹ H-NMR spectrum measured by dispersing template particles 1 obtained in Introduction Example 1 in heavy water. It is a SEM observation image of the template particle | grains 17 obtained by the synthesis example 13. It is a ¹ H-NMR spectrum measured by dispersing template particles 17 obtained in Synthesis Example 13 in heavy water. In Example 1, it is a Raman spectrum of the carbon containing metal oxide hollow particle produced using the particle | grains 5. FIG. In Example 1, it is a SEM observation image of the carbon containing metal oxide hollow particle produced using the particle | grains 5. FIG. In Example 1, it is a SEM observation image of the carbon containing metal oxide hollow particle produced using the particle | grains 5. FIG. In Example 2, it is a SEM observation image of the carbon containing metal oxide hollow particle produced using particle | grains 3 by different stirring time. In Example 2, it is a TEM observation image of the carbon composite hollow particle produced using the particle | grain 3 on the conditions for 90 minutes of stirring time. 4 is a TEM observation image of carbon-containing metal oxide hollow particles produced using particles 6 obtained in Example 4. FIG. In Example 1, Example 4, and Example 5, it is a reflection spectrum of the carbon composite silica hollow particle produced using the particle | grain 6 on different baking conditions.

Claims (8)

(I) an aqueous dispersion of monodisperse polymer fine particles (X) having hydrophilic polymer layer (x1), amino group (x2) and carboxyl group (x3) that can be solvated in an aqueous medium, and silicon or titanium A step of mixing a metal alkoxide (Y) solution comprising a metal alkoxide as a metal species and performing a sol-gel reaction of the metal alkoxide (Y) on the surface of the monodisperse polymer fine particles (X);
(II) Monodisperse polymer fine particles (X) obtained by the step (I) and coated with a metal oxide (Y ′) made of silica or titanium oxide obtained by a sol-gel reaction of a metal alkoxide (Y) Isolating and baking,
A method for producing hollow particles of carbon-containing silica or titanium oxide, characterized by comprising: Manufacturing method of the step (I) with using monodisperse polymer particles (X) mean particle diameter hollow particles of silica or titanium oxide containing carbon of claim 1 Symbol placement particles of 50nm~1000nm of. 3. The method for producing hollow particles of carbon-containing silica according to claim 1, wherein the metal alkoxide (Y) used in the step (I) is a metal alkoxide having silicon as a metal species. The method for producing carbon-containing silica or titanium oxide hollow particles according to any one of claims 1 to 3 , wherein the sol-gel reaction time in the step (I) is 1 to 3 hours. A monodisperse hollow comprising a shell mainly composed of a metal oxide (Y ′) made of silica or titanium oxide and carbon, having a shell wall thickness of 5 nm to 30 nm and an average particle diameter of 50 nm to 1000 nm. A hollow particle of carbon-containing silica or titanium oxide characterized by being a particle. Hollow particles of silica or titanium oxide containing carbon of claim 5 wherein the mass ratio of carbon is 5 to 80 wt% in the said shell. The carbon-containing silica hollow particles according to claim 5 or 6, wherein the metal oxide (Y ') is silica. The hollow particles of carbon-containing silica or titanium oxide according to any one of claims 5 to 7 , which have color developability other than white.