JP5177970B2 - Method for producing metal oxide nanoparticles, metal nanoparticles, treated metal nanoparticles and uses thereof - Google Patents

Description

The present invention relates to a method for producing metal oxide nanoparticles having an average particle diameter of 20 nm or less with a unidirectional diameter , and a large amount of metal oxide nanoparticle powder having excellent functionality and a dispersion having the powder. The present invention also relates to a manufacturing method that can be manufactured at low cost.

  Oxide nanoparticles are a material that has attracted a great deal of attention as contributing to higher functionality and higher performance of various materials such as electronic component materials, magnetic recording materials, catalyst materials, and ultraviolet absorbing materials.

  Generally, as a method for synthesizing particles, a Breaking-down process and a Building-up process are known. As a breaking-down process, a mechanical pulverization method is generally used. However, it is difficult to efficiently produce fine particles having a particle diameter of 1 μm or less, and impurities are likely to be mixed in the pulverization step. On the other hand, the Building-up process is a method of preparing particles by a chemical reaction in a gas phase or a liquid phase, and is a method capable of preparing nano-order fine particles by controlling production conditions, selecting a raw material, and the like.

  Typical examples of the gas phase method include a gas evaporation method and a gas phase reaction method (CVD). The gas evaporation method is a method of generating particles in a low-pressure inert gas by heating and evaporating a metal by a resistance heating method, a high frequency induction heating method, a plasma method, a laser method, or the like. Since these are reactions under special conditions, the cost of the apparatus is high, which is disadvantageous in terms of cost. Further, this method is not suitable for producing oxide particles having a low vapor pressure. Furthermore, since CVD has high reactivity of raw material compounds, there are many problems in handling and safety.

  On the other hand, examples of the liquid phase method include a coprecipitation method, an alkoxide method, and a hydrothermal synthesis method. In the coprecipitation method, after a metal oxide precursor such as a metal hydroxide is generated, a solution containing the precursor is heated to a temperature higher than that at which the metal oxide is generated to generate metal oxide nanoparticles. Is the method. However, there is a problem that the generated metal oxide nanoparticles grow in the heating process. The alkoxide method is a method for obtaining metal oxide fine particles by hydrolyzing a metal alkoxide (Japanese Patent Laid-Open No. 06-287005). Since this method is a synthesis method at a low temperature, aggregation is unlikely to occur, and metal oxide nanoparticles can be obtained relatively easily. However, this method can be applied only to some metal oxides, and the raw material cost is high. There is a problem. In addition, the crystallinity is not sufficient because of low-temperature synthesis, and there is a problem that the characteristics of the metal oxide originally possessed cannot be exhibited. Furthermore, the hydrothermal synthesis method involves reacting a metal oxide precursor under pressure, but there is a problem that the particles become coarse when heated for crystallization. In order to nucleate in a short time, hydrothermal reaction is performed under subcritical or supercritical conditions (Japanese Patent Laid-Open No. 2005-255450), but the reaction conditions are severe and a large amount of nanoparticles can be prepared at low cost. There was a problem that was difficult.

  In addition, spray drying method in which the solution is sprayed in hot air as small droplets and dried quickly, or spray pyrolysis method in which the solution is sprayed into a high temperature atmosphere and the solvent is instantly evaporated and the metal salt is thermally decomposed. However, since the evaporation of the solvent and the generation of the pyrolysis gas of the metal salt occur rapidly, the produced particles generally have a problem that they tend to be hollow. Further, even if the fine particles are generated, there is a problem that the metal oxide fine particles are fused in the heating process.

  Furthermore, even when oxide particles having a small primary particle diameter are prepared by the above method, aggregation and fusion often occur. In order to actually use them as functional materials, various solvents, It was necessary to improve the dispersion to the monomer and polymer. However, conventional metal oxide particles are hydrophilic and have a low affinity with organic solvents. Therefore, even if an attempt is made to perform a surface treatment with an organic surface treatment agent or the like, particles that have agglomerated or fused are not produced. In many cases, the surface treatment is performed before complete dispersion, and as a result, a uniform dispersion cannot be obtained. In addition, during the surface treatment, high-temperature and high-pressure treatment (Japanese Patent Laid-Open No. 2005-193237), homogenizer treatment is performed for the purpose of improving the affinity between the surface treatment agent and the particles, and for the purpose of re-dispersing the agglomerated or fused particles. , Ultrasonic treatment, mill treatment (Japanese Patent Laid-Open No. 2005-220264), etc., but a special device is required, and re-dispersion is difficult when agglomeration occurs even if the above treatment is used. Therefore, a simple and low-cost processing method has been desired.

JP 06-287005 JP 2005-255450 A JP-A-2005-193237 JP-A-2005-220264

  In view of the current situation as described above, an object is to produce metal oxide nanoparticles having excellent dispersion stability at low cost and on an industrial scale.

The present invention is listed below.
First invention, the water layer and the metal oxide mean particle size by directed diameter which comprises bringing a liquid consisting of an organic layer containing the precursors to react at less than 0.2 MPaG 1 MPaG is 20nm or less of the metal oxide It is a manufacturing method of a product nanoparticle. Preferably, (preparation volume of aqueous layer) / (preparation volume of organic layer) is 0.3 or more and less than 4. Further, it is preferable that the boiling point of the solvent medium contained in the organic layer is 120 ° C. or higher. The metal oxide nanoparticles are at least one element selected from Al, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Hf, La, Ce, Nd, and Sm. It is preferable that it is an oxide.

According to a second aspect of the present invention, an average particle diameter of 20 nm or less with a fixed direction diameter is obtained by reacting a liquid composed of two layers of an aqueous layer and an organic layer containing a metal oxide precursor at 0.2 MPaG or more and less than 1 MPaG. Tetragonal and / or monoclinic metal oxide nanoparticles having an amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, an OR group (where R is a hydrogen atom, an alkyl group, a cycloalkyl group) Metal oxide nanoparticles surface-treated with a compound having at least one functional group selected from: a group, an aryl group, an aralkyl group and an acyl group. is there. Further, a dispersion in which the metal oxide nanoparticles are dispersed is also included .

The third invention is a treatment characterized by treating with a compound having at least one functional group selected from an amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, and an OR group in addition to the first invention. It is a manufacturing method of a metal oxide nanoparticle. It can also be a metal oxide nanoparticle dispersion by dispersing the metal oxide nanoparticles Solvent.

In addition to the first invention, the fourth invention is an optical material having a step of treating with a compound having at least one functional group selected from an amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, and an OR group. It is a manufacturing method. The optical material can also be dispersed in a solvent to form a metal oxide nanoparticle dispersion.

  By using the present invention, metal oxide nanoparticles and metal oxide dispersions excellent in dispersion stability can be produced at a low cost on an industrial scale.

  Hereinafter, the first invention of the present invention will be described first. The liquid containing an aqueous layer and an organic layer containing a metal oxide precursor according to the present invention may be an aqueous layer and an organic layer. In some cases, the aqueous layer and the organic layer are in a “suspension” state. Or may contain an inorganic substance. The water layer and the organic layer are preferably in the range of 0.3 or more and less than 4, more preferably 0.5 or more and less than 2, in terms of (water layer charge volume) / (organic layer charge volume). If it is less than 0.3, the reaction from the precursor to the oxide is difficult to proceed, the oxide nanoparticles are not synthesized, and a long time reaction is required for synthesis, which is not preferable. On the other hand, in the case of 4 or more, since the amount of water increases, there is a problem that the amount of recovered powder in one reaction decreases. In addition, the preparation volume of an aqueous layer is the volume of the aqueous layer alone under normal pressure and room temperature before charging to a reaction container. On the other hand, the charged volume of the organic layer is the volume before the reaction at normal pressure and room temperature of the solution in which the metal oxide precursor and the organic solvent are mixed.

  The water layer according to the first aspect of the present invention may be water containing water, and is preferably pure water. An acid, an alkali, or the like can be appropriately added to the aqueous layer for adjusting the pH. The pH of the aqueous layer is preferably 4 or more and less than 9.

  The organic layer according to the first invention is sufficient if it contains at least a metal oxide precursor, but preferably contains the precursor and the solvent A. In some cases, a carboxylic acid, an amine compound, an alcohol, a surfactant, or the like that can serve as a protective agent can be included. When the precursor and the solvent A are included, the amount of the precursor is 2 to 95% by mass, preferably 5 to 90% by mass with respect to the organic layer. When the amount is less than 2% by mass, the yield decreases, which is not preferable. When the amount exceeds 95% by mass, the amount of the precursor increases and the reaction product increases. This is not preferable because it is difficult to cause a reaction.

The solvent contained in the organic layer (hereinafter referred to as “solvent A”) may be any solvent that is usually used as a solvent, and preferably has a boiling point of 120 ° C. or higher. More preferably, it is 180 degreeC, More preferably, it is 210 degreeC or more. When the boiling point of the solvent A is less than 120 ° C., the vapor pressure of the solvent A is increased, resulting in a problem that the reaction pressure is increased and the particles are easily aggregated and fused. As the type of the solvent, any solvent that can uniformly dissolve the metal oxide precursor may be used, and hydrocarbons, ketones, esters, ethers, alcohols, amines, carboxylic acids, and the like can be generally used. For example, octanol, decanol, cyclohexanol, terpineol, decane, dodecane, tetradecane, octanoic acid, 2-ethylhexanoic acid, neodecanoic acid and the like can be used.

  Metal elements used for the metal oxide nanoparticles are Mg, Al, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Hf, La, Ce, Nd, Sm. At least one element selected from can be used. Furthermore, it is also possible to prepare metal oxide nanoparticles in which two or more components are mixed by combining two or more kinds of metal oxide precursors.

  The metal precursor according to the first invention is not particularly limited as long as it is a precursor that dissolves in the organic layer, such as hydroxide, chloride, sulfide, carboxylate, amine compound, alkoxide, etc. Can be used. Among these, use of a carboxylate is preferable because the particle diameter is fine and the particles can be synthesized at a lower cost. Specifically, the carboxylate is a compound having at least one bond in which a hydrogen atom of a carboxyl group is substituted with a metal atom in the molecule. Examples of the carboxyl group include saturated monocarboxylic acid, unsaturated Chain carboxylic acid such as monocarboxylic acid, saturated polyvalent carboxylic acid, unsaturated polyvalent carboxylic acid; cyclic saturated carboxylic acid; aromatic carboxylic acid; and hydroxyl group, amino group, alkoxy group, sulfone group in the molecule A metal salt having a functional group or an atomic group can be used. Furthermore, metal carboxylates or those in which a part of the carboxylic acid residue is substituted with a hydroxyl group or an alkoxy group can be suitably used. Regarding the type of carboxylic acid, a carboxylate having 6 to 12 carbon atoms in the carboxyl group can be suitably used. Examples thereof include carboxylic acid compounds such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, 2-methylheptanoic acid, 4-methyloctanoic acid, neodecanoic acid, and salicylic acid. Of these, compounds of 2-ethylhexanoic acid and neodecanoic acid are preferably used. When the number of carbon atoms is smaller than 6, it is difficult to prepare crystallized oxide nanoparticles, and it is often impossible to use them as functional materials. When the number of carbon atoms is 12 or more, the solubility in a solvent often deteriorates, and the productivity is lowered, which is not preferable. In addition, regarding the preparation of the carboxylic acid salt, after preparing a precursor such as Mg salt, it can also be prepared by contacting with an aqueous solution of another metal compound to exchange the Mg with the metal component of the metal compound. .

  In the reaction, a dispersant may be added in addition to the solvent A, the organic layer containing the metal oxide precursor, and the water layer. Any dispersant may be used as long as it has a dispersion performance in one or more of an aqueous layer and an organic layer. Examples of the dispersant include a carboxylic acid, an amine compound, an alkoxide, a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent. The amount of the dispersant is preferably 0.01 times mol or more and less than 2 times mol with respect to the metal oxide.

The reaction pressure for reacting the aqueous layer with the organic layer having metal oxide nanoparticles is 0.2 MPaG or more and less than 1 MPaG (megapascal gauge). If it is 1 MPaG or more, there is a problem that the aggregation of particles is likely to occur and the cost of the apparatus is increased, which is not preferable. In the atmospheric pressure, it requires high temperature crystal form, since the thermal agglomeration is promoted, at least 0.2 MPaG.

  Further, the reaction temperature may be set so that the pressure in the container is less than 1 MPaG, but the reaction is preferably performed at a reaction temperature of less than 180 ° C. in consideration of the saturated water vapor pressure of water.

  Although it does not specifically limit regarding reaction time, 0.1 hr or more and less than 10 hr are preferable, and 0.5 hr or more and less than 6 hr are suitable.

The reaction system atmosphere is not particularly limited, such as air, oxygen, hydrogen, nitrogen, argon, CO ₂ , but reacting in an inert gas atmosphere such as nitrogen, argon or the like is from the viewpoint of safety and aggregation suppression. preferable. On the other hand, reacting in an air or oxygen atmosphere is not preferable in terms of safety and aggregation.

  By the above method, the metal oxide nanoparticles which are the second invention according to the present invention can be obtained. The average particle size of the particles produced according to the present invention is 1 nm or more and 20 nm or less, preferably 2 nm or more and 19 nm or less. When the thickness exceeds 20 nm, the transparency becomes low when the dispersion is used, and the utility value as a functional material is reduced. As a particle diameter measuring method, a general particle measuring method can be used. For example, a transmission electron microscope (TEM), a field emission transmission electron microscope (FE-TEM), a field emission scanning electron microscope (FE-SEM), or the like can be used as appropriate. The value of the average particle diameter is a value derived from an average value of 100 particles measured with a constant direction diameter (a diameter represented by a distance when the particles are sandwiched by parallel lines in a constant direction).

  The shape of the particles of the present invention is not particularly limited. Specific examples of the shape include a spherical shape, an elliptical spherical shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a needle shape, a columnar shape, a rod shape, a cylindrical shape, a flake shape, and a plate-like flake shape.

The particles produced according to the present invention have a BET specific surface area of 40 m ² / g or more, more preferably 80 m ² / g or more. If it is less than 40 m < ² > / g, a surface area is small and the utility value as a functional material becomes small.

  Moreover, after reacting a liquid composed of two layers of an aqueous layer and an organic layer containing a metal oxide precursor at a reaction temperature of 0.2 MPaG or more and less than 1 MPaG, the obtained metal nanoparticles can be purified. . The purification is to remove aggregates of the particles and precipitated carbon during the reaction. As an example of purification, the solution after the reaction is separated into an organic layer in the upper layer and an aqueous layer in the lower layer, and the metal oxide nanoparticles exist as precipitates in the lower part of the aqueous layer. Therefore, it can collect | recover easily by isolate | separating an organic layer and an aqueous layer, and a deposit by general methods, such as filtration. Next, in order to remove aggregated particles and carbon, toluene is added to the collected precipitate and filtered through a filter to separate the nanoparticles from large particles such as aggregated particles and carbon. Subsequently, by removing the solvent from the filtrate, a metal oxide nanoparticle powder having a small particle size and a uniform particle size can be produced.

  In the present invention, it is preferable that the solution after collecting the precipitate of oxide nanoparticles is repeatedly used again by separating only the organic layer with a separating funnel or the like. Recycling can lead to a reduction in waste liquid and a reduction in raw material costs, so that oxide nanoparticles can be prepared at a low cost.

It is possible to obtain a metal oxide nanoparticle dispersion in which the metal oxide nanoparticles are dispersed in a solvent (hereinafter referred to as solvent B) . As the solvent B used in the present invention, alcohol, ketone, ester, ether, hydrocarbon, amides can be used. For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, octanol, ethylene glycol, propylene glycol, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol Examples include monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, benzene, toluene, xylene, ethylbenzene, cyclohexane, dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like. These solvents can be used alone or in combination of two or more. In particular, it is preferable to disperse in a nonpolar solvent such as benzene, toluene, xylene and cyclohexane. This is because other polar solvents have low dispersibility and cause white turbidity, and therefore cannot be used in many cases. It can be solutions extinguishing the negative effects in applying a hydrophobic treatment to the metal oxide nanoparticles in such a case.

  Moreover, the density | concentration of the metal oxide nanoparticle in the said dispersion can be suitably set according to a use. The metal oxide nanoparticle content with respect to the dispersion is 1% by mass or more and less than 70% by mass, preferably 5% by mass or more and less than 60% by mass, and more preferably 12% by mass or more and less than 50% by mass. . When the concentration of the metal oxide nanoparticles is less than 1% by mass, the concentration of the metal oxide nanoparticles is low and not suitable for practical use. On the other hand, when it is 70% by mass or more, it is difficult to uniformly disperse and it tends to become cloudy, which is not preferable.

  In addition, since the average particle diameter of the metal oxide nanoparticles is as fine as 20 nm or less, the metal oxide nanoparticles can be uniformly dispersed in a nonpolar solvent such as toluene, xylene, or cyclohexane, and can maintain transparency. For example, when the zirconium oxide nanoparticle powder prepared by the method of the present invention is dispersed so as to be contained in 30% by mass in toluene, a transparent zirconium oxide nanoparticle-toluene dispersion can be prepared.

  The dispersion further contains metal oxide nanoparticles and further contains a plasticizer. A plasticizer (referred to as plasticizer B) can also be added. The plasticizer B is not particularly limited. For example, phosphate plasticizers such as tributyl phosphate and 2-ethylhexyl phosphate, and phthalate plasticizers such as dimethyl phthalate and dibutyl phthalate. Aliphatic-basic ester plasticizers such as butyl oleate and glycerol monooleate; aliphatic dibasic ester plasticizers such as dibutyl adipate and di-2-ethylhexyl sebacate; diethylene glycol dibenzoate, tri Conventionally known plasticizers such as dihydric alcohol ester plasticizers such as ethylene glycol di-2-ethylbutyrate; oxyacid ester plasticizers such as methyl acetylricinoleate and tributyl acetylcitrate can be mentioned.

  A monomer can be added to the dispersion. The monomer used is not particularly limited, and examples thereof include (meth) acrylic monomers such as (meth) acrylic acid and (meth) acrylic acid esters, styrene monomers such as styrene, vinyltoluene, and divinylbenzene, vinyl chloride, Conventionally known monomers such as vinyl monomers such as vinyl acetate can be listed.

In the second invention and the third invention , the metal oxide nanoparticles are added to an amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, an OR group (where R is a hydrogen atom, an alkyl group, a cycloalkyl group). A compound having at least one functional group selected from an aryl group, an aralkyl group, and an acyl group (referred to as a “surface treatment agent”) and a solution. The surface-treated metal oxide nanoparticles (referred to as “treated metal oxide nanoparticles”) obtained by heating with, and the production method. By applying the treatment to the metal oxide nanoparticles, the dispersibility of the particles in various solvents and monomers can be improved.

  The surface treatment agent is not particularly limited as long as it is a compound having at least one functional group selected from an amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, and an OR group, but aluminum trimethoxide. , Aluminum triethoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide, monosec butoxy aluminum diisopropylate, aluminum triethoxyethoxy ethoxide, aluminum phenoxide Such as aluminum alkoxide, diisopropoxy aluminum ethyl acetoacetate, diisopropoxy aluminum alkyl acetoacetate, diisopropoxy aluminum monometa Various aluminum-based coupling agents such as relate, aluminum stearate oxide trimer, isopropoxy aluminum alkyl acetoacetate mono (dioctyl phosphate), etc .; titanium n-butoxide, titanium tetra-tert-butoxide, titanium tetra-sec-butoxide, titanium tetra Ethoxide, Titanium tetraisopropoxide, Titanium tetra-2-ethylhexoxide, Titanium tetraisobutoxide, Titanium lactate, Titanium tetramethoxide, Titanium tetra (methoxypropoxide), Titanium tetra (methylphenoxide), Titanium tetra n- Nonyloxide, titanium tetra-n-butoxide, titanium tetrastearyloxide, titanium bis (tri (Tanolamine) -diisopropoxide, titanium alkoxide, isopropyl triisostearoyl titanate, isopropyl trioctanoyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, isopropyl tris ( Dioctyl pyrophosphate) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetra (2, 2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, isop Various titanium-based coupling agents such as propyl dimethacrylic isostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate, isopropyl tricumyl phenyl titanate; vinyl trimethoxy silane, vinyl trichloro silane, vinyl triethoxy silane, 2- (3,4 epoxy) (Cyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltolmethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyl Methyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltolethoxylane, -Various silane coupling agents such as acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, hexamethyldisilanezan; Zirconium tetra n-butoxide, zirconium tetra tert-butoxide, zirconium tetra 2-ethyl hexoxide, zirconium tetraisobutoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetra n-propoxide, zirconium tetra (2-methyl Zirconium alkoxides such as 2-butoxide), zirconium di-n-butoxide (bis-2,4-pentanedionate), zirconium tri-n-butoxide pentadionone Various zirconium compounds such as zirconium dimethacrylate dibutoxide, etc. Hydroxystearic acid, hydroxycarboxylic acids such as salicylic acid, ether carboxylic acids such as 2- [2- (2-methoxyethoxy) ethoxy] acetic acid, carboxylated polybutadiene, carboxylated poly Carboxylic acid coupling agents such as isoprene and maleic acid-modified polypropylene are preferred. More preferred are silane coupling agents, hydroxycarboxylic acids, and ether carboxylic acids.

  Regarding the heat treatment method, a mixture containing metal oxide nanoparticles and a surface treatment agent may be heat treated. For example, after dispersing metal oxide nanoparticles in a solvent, a surface treatment agent may be added as appropriate, followed by heat treatment. Regarding heating temperature, it is 0 degreeC or more and less than 180 degreeC, Preferably it is 10 degreeC or more and less than 120 degreeC. More preferably, it is 20 degreeC or more and less than 100 degreeC. Below 0 ° C, the reaction does not proceed. On the other hand, 180 ° C. or higher is not preferable from the viewpoint of safety and cost. The reaction time is 0.1 hr or more and less than 10 hr, preferably 0.3 hr or more and less than 3 hr.

  The solvent used for the surface treatment may be any solvent that uniformly disperses the metal oxide nanoparticles, and is preferably toluene, xylene, or cyclohexane. The ratio of the metal oxide nanoparticles in the solution is preferably 0.1% by mass or more and less than 50% by mass. The particles of the present invention have very good dispersibility in toluene and xylene, and can be reacted with the surface treatment agent in a uniformly dispersed state, so that no special equipment is required and mild conditions are used. Since it can be processed under a short time, it is a very excellent surface treatment method. On the other hand, addition of water, alcohols and ketones having 4 or less carbon atoms as in the conventional method is not preferable because secondary aggregation of the metal oxide nanoparticles occurs and the surface treatment cannot be performed uniformly. By performing this treatment, the particles having an affinity for a nonpolar solvent originally have an affinity for a highly polar solvent. This is completely different from the conventional surface treatment method in which highly hydrophilic oxide nanoparticles are changed to hydrophobic.

  The surface treatment agent is 1% by mass or more and less than 40% by mass, and preferably 3% by mass or more and less than 30% by mass with respect to the metal oxide nanoparticles. More preferably, it is 5 mass% or more and less than 25 mass%. When the amount is less than 3% by mass, the effect of the surface treatment is small and the dispersibility in solvents other than toluene, xylene and cyclohexane is not improved. On the other hand, when it is 40% by mass or more, the ratio of the surface treatment agent to the metal oxide nanoparticles increases. As a result, in the organic matrix material in which the surface-treated metal oxide nanoparticles are dispersed, a substantial amount of the metal oxide nanoparticle is inherently required to express the high refractive power and ultraviolet blocking ability of the treated metal oxide nanoparticles. Since mixing of particles is required, it is not preferable.

The treated metal oxide nanoparticles can be dispersed in a solvent (hereinafter referred to as solvent C) to obtain a treated metal oxide nanoparticle dispersion. As the solvent C, alcohol, ketone, ester, ether, hydrocarbon and amide can be used. For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, octanol, ethylene glycol, propylene glycol, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol Examples include monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, benzene, toluene, xylene, ethylbenzene, cyclohexane, dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like. These solvents can be used alone or in combination of two or more.

  The treated metal oxide nanoparticles are appropriately dispersed in the various solvents to obtain a transparent dispersion. The density | concentration of the oxide nanoparticle in the said dispersion can be suitably set according to a use. The treated metal oxide nanoparticles are 1% by mass or more and less than 60% by mass, preferably 5% by mass or more and less than 55% by mass, and more preferably 12% by mass or more and less than 50% by mass with respect to the dispersion. . If the concentration of the oxide nanoparticles is less than 1% by mass, only an extra dispersion medium is required. On the other hand, when it is 60% by mass or more, it is difficult to uniformly disperse and it tends to become cloudy, which is not preferable. In addition, since the particle | grains manufactured by this invention are very fine with an average particle diameter of 20 nm or less, transparency can be hold | maintained if it disperse | distributes uniformly in the said solvent.

  A plasticizer (referred to as “plasticizer C”) can be further added to the dispersion. The plasticizer C is not particularly limited, and examples thereof include phosphate ester plasticizers such as tributyl phosphate and 2-ethylhexyl phosphate, phthalate plasticizers such as dimethyl phthalate and dibutyl phthalate, and butyl oleate. , Aliphatic-basic ester plasticizers such as glycerin monooleate, aliphatic dibasic ester plasticizers such as dibutyl adipate and di-2-ethylhexyl sebacate; diethylene glycol dibenzoate, triethylene glycol di- Conventionally known plasticizers such as dihydric alcohol ester plasticizers such as 2-ethylbutyrate; oxyester plasticizers such as methyl acetylricinoleate and tributyl acetylcitrate can be mentioned.

  A monomer can be further added to the dispersion. The monomer is not particularly limited, and examples thereof include (meth) acrylic monomers such as (meth) acrylic acid and (meth) acrylic esters, styrene monomers such as styrene, vinyltoluene, and divinylbenzene, vinyl chloride, and vinyl acetate. Conventionally known monomers such as vinyl monomers such as

  The content of the inorganic nanoparticles in the monomer dispersion is not particularly limited, but is preferably 2 to 80% by weight of the whole monomer dispersion, more preferably 5 to 60% by weight. If so, the viscosity and the like are low and easy to handle. The monomer dispersion is useful for applications such as a resin composition and a resin molded body in which inorganic nanoparticles are dispersedly contained. Examples of the method for producing the monomer dispersion include a method in which metal oxide nanoparticles are added to the monomer and dispersed.

The fourth invention is an optical material using those said treated metal oxide nanoparticles. The particles have a particle size of 20 nm or less and are excellent in dispersibility in a solvent. This effect can be widely used in various applications such as conductive materials, ultraviolet blocking materials, transparent films, electromagnetic wave absorbers, optical materials, and catalyst materials. In particular, zirconium oxide nanoparticles have a tetragonal crystal structure, an average particle diameter of 20 nm or less, and excellent dispersibility in various solvents, and therefore can be suitably used as a refractive index control material for optical materials.
The polymer binder used is a homopolymer having acrylic acid ester, methacrylic acid ester or the like as a structural unit or a copolymer comprising two or more monomers, polycarbonate resin, polyester resin, polyether resin, polyamide resin, polyimide resin. And thermoplastic resins such as polyolefin resin and polystyrene resin, and thermosetting resins such as epoxy resin, silicon resin and radical polymerizable resin. Examples of the monomer include vinyl monomers such as acrylic acid ester, methacrylic acid ester, and styrene.
As a dispersion method of the binder and the zirconium oxide nanoparticles and / or the treated zirconium oxide nanoparticles, for example, when the thermoplastic resin is mixed with the zirconium oxide nanoparticles and / or the treated zirconium oxide nanoparticles, specifically, A solution in which a thermoplastic resin is dissolved and a dispersion in which zirconium oxide nanoparticles and / or treated zirconium oxide nanoparticles are uniformly dispersed are uniformly mixed, and the solvent is removed by heating under reduced pressure. A method in which zirconium oxide nanoparticles and / or treated zirconium oxide nanoparticle powders are blended as they are in a molten state and melt-kneaded, and zirconium oxide nanoparticles and / or treated zirconium oxide nanoparticles are uniformly in a molten state of a thermoplastic resin. Mix and disperse the dispersed dispersion How to heating under reduced pressure removing the solvent, and the like later.
Examples of optical material applications include lenses (for example, eyeglass lenses, optical equipment lenses, optoelectronic lenses, laser lenses, CD pickup lenses, automotive lamp lenses, OHP lenses, etc.), optical fibers, optical waveguides, light Suitable for applications such as filters, optical adhesives, optical disk substrates, display substrates, coating materials, prisms and the like.
The definition of dispersion in the present invention is a mixture of metal oxide nanoparticle powder or treated metal oxide nanoparticles weighed so as to be 10% by mass in a sample solvent, and after stirring for 10 minutes, quantitative filter paper (Advantech) The amount of powder recovered by Toyo Co., Ltd. No. 5C) is less than 3% of the charged powder amount, and particles having an average particle diameter of 20 nm or less are not agglomerated, so it is transparent in the solvent. It can maintain the sex.

The measurement of each physical property in an Example was implemented as follows.

(BET specific surface area)
The specific surface area of zirconium oxide was measured using a fully automatic BET specific surface area measuring device (Macsorb Model 1210 manufactured by Mounttech). In the adsorption process, cooling with liquid nitrogen was performed.

(Qualitative analysis)
Identification of the crystal state of the metal oxide was performed using XRD (Spectris Co., Ltd. fully automatic multipurpose X-ray diffractometer XPPer Pro).

(Particle size)
The particle diameter of the metal oxide nanoparticles was measured using an FE-SEM (Hitachi Ultra High Resolution Field Emission Scanning Electron Microscope S-4800). The value of the average particle diameter is a value derived from an average value of 100 particles measured with a constant direction diameter (a diameter represented by a distance when the particles are sandwiched by parallel lines in a constant direction).

Example 1
Tetradecane and neodecanoic acid were mixed to prepare a 40 mass% neodecanoic acid-tetradecane solution. Next, add an equal amount of water, add a reagent of zirconium oxychloride to the solvent, react at 60 ° C. for 1 hour with good stirring, and then separate the aqueous layer to prepare a zirconium neodecanoate solution. To do.
Next, a mixture of 500 cc of a neodecanoic acid zirconium-tetradecane solution and 500 cc of water is charged into an autoclave equipped with a stirrer, and the atmosphere in the reaction vessel is replaced with nitrogen gas. Then, it heated to 175 degreeC and synthesize | combined oxide microparticles | fine-particles by making 3Hr reaction. The pressure at the end of the temperature increase was 0.9 MPaG.

The solution after the reaction was taken out, and the precipitate accumulated at the bottom was collected by filtration. The precipitate was washed with acetone, dried, and then dispersed in toluene to give a cloudy solution. Next, it filtered again with the quantitative filter paper (Advantech Toyo Co., Ltd. No. 5C) as a refinement | purification process, and removed the coarse particle etc. in a deposit. Next, when the toluene in the filtrate was dried under reduced pressure, a white powder could be recovered.
When the particle diameter of the recovered powder was analyzed by FE-SEM, zirconium oxide nanoparticles having an average particle diameter of 5 nm with a fixed direction diameter could be confirmed.
Moreover, in order to confirm the crystal structure of white powder, when it confirmed with XRD, it was confirmed that it has a tetragonal structure.
When 10 g of the synthesized zirconium oxide nanoparticles were dispersed in 90 g of toluene, a transparent dispersion liquid was obtained.

(Example 2)
Dodecane and 2-ethylhexanoic acid are mixed to prepare a 40 mass% ethylhexanoic acid-dodecane solution. Next, an equivalent amount of water was added, and a zinc acetate reagent was further added to the solvent. The mixture was reacted at 60 ° C. for 1 hour with good stirring, and then the aqueous layer was separated to prepare zinc 2-hexanoate. To do.

Next, a mixture of 500 cc of 2-ethylhexanoic acid zinc-dodecane solution and 500 cc of water is charged into an autoclave equipped with a stirrer, and the atmosphere in the reaction vessel is replaced with nitrogen gas. Then, it heated to 150 degreeC and synthesize | combined oxide microparticles | fine-particles by making 3Hr reaction. The reaction pressure at that time was 0.5 MPaG. In the same manner as in Example 1, the precipitate contained in the solution after the reaction was recovered and then dispersed in toluene to obtain a cloudy solution.
Next, when toluene was dried under reduced pressure from the filtrate that passed through the quantitative filter paper (No. 5C, manufactured by Advantech Toyo Co., Ltd.), white powder could be recovered.
When the particle diameter of the collected powder was analyzed by FE-SEM, nanoparticles having an average particle diameter of 10 nm with a fixed direction diameter could be confirmed.

(Example 3)
Tetradecane and neodecanoic acid are mixed to prepare a 40 mass% ethylhexanoic acid-tetradecane solution. Next, an equivalent amount of water is added, and a copper acetate reagent is further added to the solvent. The mixture is reacted at 40 ° C. for 1 hour with good stirring, and then the aqueous layer is separated to prepare copper 2-hexanoate. To do.

Next, a mixture of 500 cc of 2-ethylhexanoic acid copper-tetradecane solution and 500 cc of water is charged into an autoclave equipped with a stirrer, and the atmosphere in the reaction vessel is replaced with nitrogen gas. Then, it heated to 120 degreeC and synthesize | combined oxide microparticles | fine-particles by making 3Hr reaction. The reaction pressure at that time was 0.2 MPaG. The precipitate contained in the solution after the reaction was collected and then dispersed in toluene to obtain a reddish brown solution.
Next, when toluene was dried under reduced pressure from the filtrate that passed through the quantitative filter paper (No. 5C manufactured by Advantech Toyo Co., Ltd.), a reddish brown powder could be recovered.
When the particle diameter of the collected powder was analyzed by FE-SEM, nanoparticles having an average particle diameter of 15 nm with a fixed direction diameter could be confirmed.

Example 4
Tetradecane and neodecanoic acid were mixed to prepare a 40 mass% neodecanoic acid-tetradecane solution. Next, water is added, a reagent of zirconium oxychloride is further added to the solvent, the mixture is allowed to react at 60 ° C. for 1 hour with good stirring, and then the aqueous layer is separated to prepare a zirconium neodecanoate solution. Next, a mixture of 500 cc of a neodecanoic acid zirconium-tetradecane solution and 100 cc of water at a ratio shown in Table 1 is charged into the autoclave equipped with a stirrer, and the atmosphere in the reaction vessel is replaced with nitrogen gas. Then, the synthesis | combination of the oxide fine particle was tried by heating to 175 degreeC and making it react for 3Hr. Particles were collected by the same method as in Example 1. Although the average particle diameter by the fixed direction diameter was 7 nm, which was almost the same as that of the example, the synthesis amount of the particles was as small as 1/5 times that of Example 1, and tetragonal crystals and monoclinic crystals were mixed. Zirconium oxide particles.

(Comparative Example 1)
Tetradecane and neodecanoic acid were mixed to prepare a 40 mass% neodecanoic acid-tetradecane solution. Next, water is added, a reagent of zirconium oxychloride is further added to the solvent, the mixture is allowed to react at 60 ° C. for 1 hour with good stirring, and then the aqueous layer is separated to prepare a zirconium neodecanoate solution. Next, 500 cc of a neodecanoic acid zirconium-tetradecane solution is charged into an autoclave equipped with a stirrer, and the atmosphere in the reaction vessel is replaced with nitrogen gas. Then, the synthesis | combination of the oxide fine particle was tried by heating to 175 degreeC and making it react for 3Hr. In the case where the reaction was carried out without adding water at all, formation of particulate matter was not confirmed.

(Example 5)
This is a step of treating the surface of the metal oxide nanoparticles. 1.5 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) was added to a solution in which 10 g of the zirconium oxide nanoparticles synthesized in Example 1 were dispersed in 90 g of toluene. After refluxing the above solution at 80 ° C. for 1 hr, the solvent was removed under a reduced pressure atmosphere to prepare zirconium oxide nanoparticles subjected to surface treatment with 3-methacryloxypropyltrimethoxysilane.

Next, when 5 g of the surface-treated zirconium oxide particles were mixed with 50 g of methyl isobutyl ketone and stirred, the treated zirconium oxide nanoparticle dispersion was transparent.
When the zirconium oxide particles after the surface treatment were analyzed by FT-IR, the Si bond derived from the silane coupling agent was combined with the C—H bond (2800 to 3000 cm −1) recognized before the surface treatment. -O-C (1000-1130 cm-1) was confirmed.

(Example 6)
1.5 g of hydroxystearic acid was added to a solution in which 10 g of the zirconium oxide nanoparticles synthesized in Example 1 were dispersed in 90 g of toluene. After refluxing the solution at 100 ° C. for 1 hr, the solution after the reaction was transparent, but became cloudy when 200 g of acetone was added. Aggregated and cloudy particles were separated and collected with a filter paper and dried at 50 ° C. for 1 hr to prepare zirconium oxide particles treated with hydroxystearic acid. Next, when 5 g of the surface-treated zirconium oxide particles were mixed with 50 g of ethanol and stirred, the treated zirconium oxide nanoparticle dispersion was transparent.

  When the treated zirconium oxide nanoparticles prepared by the same preparation method were dispersed in MMA monomer, butyl acetate, and MIBK, the treated zirconium oxide particle dispersion was transparent.

(Example 7)
To a solution in which 10 g of the zirconium oxide nanoparticles synthesized in Example 1 were dispersed in 90 g of toluene, 1.5 g of 2- [2- (2-methoxyethoxy) ethoxy] acetic acid was added.
The solution was refluxed at 80 ° C. for 1 hr, and then the solvent was removed under a reduced pressure atmosphere to prepare treated zirconium oxide nanoparticles subjected to surface treatment with 2- [2- (2-methoxyethoxy) ethoxy] acetic acid. .

  Next, when 5 g of the treated zirconium oxide nanoparticles were mixed with 50 g of MMA monomer and stirred, the treated zirconium oxide nanoparticle dispersion was transparent. Similarly, when 5 g of treated zirconium oxide nanoparticles were mixed with cyclohexanone and stirred, the treated zirconium oxide nanoparticle dispersion was transparent.

The present invention can produce metal oxide nanoparticles and / or metal oxide nanoparticle dispersions excellent in dispersion stability at a low cost on an industrial scale, and the nanoparticles or / and dispersions. It is a technique used for optical materials using

Claims (10)

Metal oxide nanoparticles having an average particle diameter of 20 nm or less with a unidirectional diameter, wherein a liquid composed of two layers of an aqueous layer and an organic layer containing a metal oxide precursor is reacted at 0.2 MPaG or more and less than 1 MPaG Manufacturing method. 2. The method for producing metal oxide nanoparticles according to claim 1, wherein (preparation volume of aqueous layer) / (preparation volume of organic layer) is 0.3 or more and less than 4. 3. The method for producing metal oxide nanoparticles according to claim 1 or 2, wherein the solvent contained in the organic layer has a boiling point of 120 ° C or higher. The metal oxide nanoparticles according to any one of claims 1 to 3, wherein Al, Ti, V, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, Sn, Sb, Hf, La, Ce, Nd, A method for producing metal oxide nanoparticles, which is an oxide of at least one element selected from Sm. A liquid composed of two layers of an aqueous layer and an organic layer containing a metal oxide precursor is reacted at 0.2 MPaG or more and less than 1 MPaG. Or monoclinic metal oxide nanoparticles ,
An amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, an OR group (where R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an acyl group). Surface-treated with a compound having at least one functional group selected from:
Metal oxide nanoparticles. A dispersion in which the metal oxide nanoparticles according to claim 5 are dispersed. A manufacturing method according to any one of claims 1 to 4 ,
An amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, an OR group (where R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an acyl group). A method of producing a metal oxide nanoparticle dispersion comprising a step of treating with a compound having at least one functional group selected from : A manufacturing method according to any one of claims 1 to 4,
An amino group, a thiol group, a vinyl group, a carboxyl group, an epoxy group, an OR group (where R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, and an acyl group). A step of treating with a compound having at least one functional group selected from:
Manufacturing method of optical material. The manufacturing method of any one of Claims 1-4, or the manufacturing method of the metal oxide nanoparticle dispersion which has the process of disperse | distributing this metal oxide nanoparticle to a solvent. The manufacturing method of any one of Claims 1-4, or the manufacturing method of the optical material which has the process of disperse | distributing this metal oxide nanoparticle to a solvent.