JP2010058031A - Dispersion of fine particle of metal oxide and method of manufacturing the same - Google Patents

Abstract

A nano-sized metal oxide fine particle dispersion that is less agglomerated and can maintain transparency even when aged at room temperature, and the metal oxide fine particle dispersion can be produced efficiently and inexpensively. A method for producing a metal oxide fine particle dispersion is provided.
A method for producing a metal oxide fine particle dispersion comprising adding a metal alkoxide solution containing at least one metal alkoxide and at least one acid compound to a solvent containing at least one acid compound. It is. An embodiment in which the temperature of the solvent when the metal alkoxide solution is added to a solvent containing at least one acidic compound is 30 ° C. or higher, an embodiment in which the acidic compound is any one of hydrochloric acid, nitric acid, and acetic acid, Etc. are preferable.
[Selection figure] None

Description

  The present invention relates to a transparent and stable nano-sized metal oxide fine particle dispersion and a method for producing the metal oxide fine particle dispersion.

  Since metal nanoparticles have a large surface energy due to a large surface area / volume ratio, it is difficult to uniformly disperse the nanoparticles as primary particles. As a method for uniformly dispersing such nanoparticles, there is a method of adding a surface modifier such as a water-soluble polymer compound or a surfactant. However, it is not preferable to use surface modifiers such as water-soluble polymer compounds and surfactants because they may hinder subsequent steps.

Therefore, in Patent Document 1, a white turbid sol obtained by adding a metal alkoxide solution to hydrochloric acid or sulfuric acid solution and aging at room temperature and 50 ° C. is pulverized with a jet mill at an appropriate pH to give a fine white color. A method for forming a transparent and stable sol has been proposed. However, the jet mill in this proposal aims to disperse the cloudy titanium oxide sol, which is a secondary agglomerate, in the primary particles. The primary particles are not dispersed stably from the beginning, but the primary particles are uniformly dispersed during synthesis. If it can be done, it is not necessary.
Patent Document 2 proposes a titanium oxide sol containing chlorine ions and a specific amount of other Bronsted base other than the chlorine ions. This titanium oxide sol is produced by hydrolyzing titanium tetrachloride in the presence of at least one Bronsted acid. However, this proposal has a problem that titanium tetrachloride is highly reactive and easily reacts with moisture in the air, so that it is difficult to handle and industrialization is difficult.

  Therefore, a nano-sized metal oxide fine particle dispersion that has little aggregation and can maintain transparency even when aged at room temperature, and a metal oxide that can efficiently and inexpensively produce the metal oxide fine particle dispersion The present situation is that a rapid provision of a method for producing a fine particle dispersion is desired.

JP 2007-39285 A WO99 / 058451 pamphlet

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention efficiently and inexpensively produces a nano-sized metal oxide fine particle dispersion that is less agglomerated and can maintain transparency even when aged at room temperature. It is an object of the present invention to provide a method for producing a metal oxide fine particle dispersion that can be used.

  As a result of intensive studies by the inventor in order to solve the above problems, a transparent and stable nano-sized metal is synthesized by adding a metal alkoxide solution containing an acidic compound (acid) to an aqueous solution containing an acidic compound. It has been found that an oxide fine particle dispersion can be efficiently produced at low cost.

This invention is based on the said knowledge by this inventor, and as a means for solving the said subject, it is as follows. That is,
<1> A method for producing a metal oxide fine particle dispersion, comprising adding a metal alkoxide solution containing at least one kind of metal alkoxide and at least one kind of acidic compound to a solvent containing at least one kind of acidic compound. is there.
<2> The method for producing a metal oxide fine particle dispersion according to <1>, wherein the temperature of the solvent when the metal alkoxide solution is added to the solvent containing at least one kind of acidic compound is 30 ° C. or higher. .
<3> The method for producing a metal oxide fine particle dispersion according to any one of <1> to <2>, wherein the acidic compound is any one of hydrochloric acid, nitric acid, and acetic acid.
<4> The method for producing a metal oxide fine particle dispersion according to any one of <1> to <3>, wherein the content of the acidic compound in the metal alkoxide solution is 0.1 mol / L to 5.0 mol / L. It is.
<5> The method for producing a metal oxide fine particle dispersion according to any one of <1> to <4>, wherein the content of the acidic compound in the solvent is 0.1 mol / L to 5.0 mol / L. .
<6> A metal oxide fine particle dispersion produced by the method for producing a metal oxide fine particle dispersion according to any one of <1> to <5>.
<7> The metal oxide fine particle dispersion according to <6>, wherein the metal oxide fine particles include a metal oxide containing one kind of metal or a composite metal oxide containing two or more kinds of metals.

In general, when an acidic compound (acid) is added, the metal oxide fine particle dispersion (sol) is stabilized. However, when an acidic compound is added only to the metal alkoxide solution when a solution containing the metal alkoxide is added to the solvent, the initial acid is reduced. The cloudiness occurs due to the small amount. On the other hand, when an acidic compound is added only to the solvent, it does not become cloudy at the beginning, but it becomes cloudy with time. This is because when an acidic compound is added only to a solvent or only to a metal alkoxide solution, a region with a small amount of acidic compound is locally generated, and locally present metal oxide fine particles having a small surface charge are aggregated together. It is thought that.
In the present invention, when an acidic compound is added to both the solvent and the metal alkoxide solution, the acidic compound is not localized, so the synthesized primary particles are uniformly dispersed as they are and are allowed to age at room temperature. Even transparency can be maintained.

  According to the present invention, a nano-sized metal oxide fine particle dispersion that can solve conventional problems, has little aggregation, and can maintain transparency even when aged at room temperature, and the metal oxide fine particles It is possible to provide a method for producing a metal oxide fine particle dispersion capable of producing a dispersion efficiently and inexpensively.

(Metal oxide fine particle dispersion and method for producing metal oxide fine particle dispersion)
The method for producing a metal oxide fine particle dispersion of the present invention includes a step of adding a metal alkoxide solution containing at least one metal alkoxide and at least one acidic compound to a solvent containing at least one acidic compound, Further, it includes other steps as necessary.
The metal oxide fine particle dispersion of the present invention is produced by the method for producing the metal oxide fine particle dispersion of the present invention.
Hereinafter, the details of the metal oxide fine particle dispersion of the present invention will be clarified through the description of the method for producing the metal oxide fine particle dispersion of the present invention.

<Metal alkoxide solution>
The metal alkoxide solution contains at least one metal alkoxide and at least one acidic compound, and contains a dispersion solvent and, if necessary, other components.

-Metal alkoxide-
Examples of the metal in the metal alkoxide include Ti, Zn, Ge, Zr, Hf, Si, Sn, Mn, Ga, Mo, In, Sb, Ta, V, Y, and Nb. Among these, Ti and Zr are particularly preferable.
Accordingly, tetraalkoxytitanium and alkoxyzirconium are suitable as the metal alkoxide.
Examples of the tetraalkoxytitanium include tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, tetraisobutoxytitanium, tetrakis (2-methylpropoxy) titanium, tetrakispentoxytitanium, tetrakis ( 2-ethylbutoxy) titanium, tetrakis (octoxy) titanium, tetrakis (2-ethylhexoxy) titanium and the like. If the alkoxyl group contained in the tetraalkoxytitanium has too many carbon atoms, hydrolysis may be insufficient. If the alkoxy group has too few carbon atoms, the reactivity may increase and the reaction control may be difficult. For this reason, tetrapropoxytitanium and tetraisopropoxytitanium are particularly preferred.
Examples of the alkoxyzirconium include methoxyzirconium, ethoxyzirconium, propoxyzirconium, butoxyzirconium, isobutoxyzirconium, kiss (2-methylpropoxy) zirconium and the like. Of these, butoxyzirconium is particularly preferred.

-Acidic compounds-
There is no restriction | limiting in particular as said acidic compound, According to the objective, it can select suitably, For example, hydrochloric acid, nitric acid, formic acid, acetic acid, sulfuric acid, perchloric acid, oxalic acid, lactic acid etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, hydrochloric acid, nitric acid, and acetic acid are particularly preferable. On the other hand, an acid having a large anion such as sulfuric acid or an acid that forms a stable complex such as oxalic acid may adsorb and interfere with particle formation.
The content of the acidic compound in the metal alkoxide solution is preferably 0.1 mol / L to 5.0 mol / L, and more preferably 0.4 mol / L to 3.5 mol / L.
When the content is less than 0.1 mol / L, the dispersion of the particles may be insufficient. When the content exceeds 5.0 mol / L, the electrolyte doubles and the charge double layer of the particles collapses. Conversely, aggregation may proceed.

-Dispersion solvent-
Examples of the dispersion solvent include water, alcohols, ketones, aldehydes, ethers, esters, and the like.
Examples of the alcohols include methanol, ethanol, propanol, isopropanol, and butanol.
Examples of the ketones include acetone and methyl ethyl ketone.
Examples of the ethers include dioxane and diethyl ether.

<Solvent containing at least one acidic compound>
Water is used as the solvent, and a solvent other than water can be added as necessary. As the solvent other than water, those compatible with water are preferable, and examples thereof include alcohols, ketones, aldehydes, ethers, esters and the like.
Examples of the alcohols include methanol, ethanol, propanol, isopropanol, and butanol.
Examples of the ketones include acetone and methyl ethyl ketone.
Examples of the ethers include dioxane and diethyl ether.

As the acidic compound in the solvent, those similar to the acidic compound in the metal alkoxide solution can be used. The acidic compound in the solvent and the acidic compound in the metal alkoxide solution may be the same or different.
The content of the acidic compound in the solvent is preferably 0.1 mol / L to 5.0 mol / L, and more preferably 0.4 mol / L to 3.0 mol / L. When the content is less than 0.1 mol / L, the reaction may not be fully controlled or the dispersion of the particles may be insufficient. When the content exceeds 5.0 mol / L, aggregation may proceed. .

In the present invention, the temperature of the solvent when the metal alkoxide solution is added to the solvent containing the at least one acidic compound is preferably 30 ° C. or higher, more preferably 50 ° C. to 90 ° C. preferable. When the temperature of the solvent is less than 30 ° C., the dehydration reaction or dealcoholization reaction is slowed, and productivity may be reduced, or unreacted substances may react with time to promote aggregation.
In addition, in order to raise the temperature of the reaction liquid after adding the metal alkoxide solution to the solvent containing at least one kind of acidic compound to increase the reactivity with respect to the temperature of the solvent, or to suppress aggregation. Although it can be lowered, it is preferable to maintain the initial temperature.

  The method for adding the metal alkoxide solution to the solvent containing at least one kind of acidic compound is not particularly limited and may be appropriately selected depending on the purpose. May be added.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a washing | cleaning process etc. are mentioned. The washing step is not particularly limited as long as excess ions can be removed, and a conventionally known method can be employed, for example, an ultrafiltration membrane method, a filtration separation method, a centrifugal filtration method, an ion exchange resin. Law.

The content of the metal oxide fine particles in the metal oxide fine particle dispersion produced by the method for producing a metal oxide fine particle dispersion of the present invention is preferably 0.1% by mass to 20% by mass.
The metal oxide fine particles include at least one metal oxide selected from Ti, Zn, Ge, Zr, Hf, Si, Sn, Mn, Ga, Mo, In, Sb, Ta, V, Y, and Nb. Or a composite metal oxide formed by combining two or more of these metals.
The metal oxide is, for example _{ZnO, GeO 2, TiO 2,} ZrO 2, HfO 2, SiO 2, Sn 2 O 3, Mn 2 O 3, Ga 2 O 3, Mo 2 O 3, In 2 O 3, _{sb 2 O 3, Ta 2 O} 5, V 2 O 5, Y 2 O 3, etc. _Nb 2 _{O 5} and the like.
Examples of the composite metal oxide include a composite oxide of titanium and zirconium, a composite oxide of titanium, zirconia and hafnium, a composite oxide of titanium and barium, a composite oxide of titanium and silicon, and a composite of titanium, zirconium and silicon. Examples thereof include oxides, composite oxides of titanium and tin, and composite oxides of titanium, zirconia, and tin.
Among these, it is preferable that 60 atomic% or more of all metal atoms constituting the composite metal oxide is Ti, and 70 atomic% or more of all metal atoms constituting the composite metal oxide is Ti and Sn. It is more preferable. Thereby, a high refractive index metal oxide fine particle dispersion is obtained.
It is preferable that the composite metal oxide is composed of Ti, Sn, and Zr, and 70 atomic% to 98 atomic% of the total metal of the composite metal oxide is Ti and Sn, and the rest is Zr.
It is preferable that the X-ray diffraction pattern of the composite metal oxide has a rutile structure.

The average particle diameter of the metal oxide fine particles is preferably 1 nm to 20 nm, and more preferably 3 nm to 10 nm. When the average particle diameter exceeds 20 nm, Rayleigh scattering is large, which may cause haze and may limit application.
Here, the average particle diameter of the metal oxide fine particles can be determined by directly measuring a 4% by mass aqueous solution of metal oxide fine particles using, for example, a Microtrac particle size distribution measuring device manufactured by NIKKISO. it can. Alternatively, the particle size can be obtained by dropping the dispersion on a carbon-deposited copper mesh (microgrid) and observing the dried one with a transmission electron microscope (TEM). Specifically, after observing an image observed with a transmission electron microscope (TEM) on a photographic negative or taking it in as a digital image, a print having a size capable of sufficiently observing the particle size is created. The particle size can be obtained from this print. Since a transmission electron microscope (TEM) image is a two-dimensional image, it is difficult to obtain an accurate particle diameter particularly in the case of an amorphous particle, but the projected area of 300 or more particles obtained as a two-dimensional image is difficult. Can be measured as the particle size. The primary particle size can also be obtained from the full width at half maximum of X-ray diffraction using the Scherrer equation.

The light transmittance of the metal oxide fine particle dispersion is preferably 90% or more. When the light transmittance is less than 90%, the light transmittance when the composite molded body is obtained is reduced, and it cannot be substantially used as an optical member.
The light transmittance is measured by using a UV-visible absorption spectrum measuring device “UV-3100” (manufactured by Shimadzu Corporation) with a wavelength of 800 nm, for example, by placing a metal oxide fine particle dispersion in a quartz cell having an optical path length of 10 mm. Can be measured.

<Application>
The metal oxide fine particle dispersion produced by the method for producing a metal oxide fine particle dispersion of the present invention is added with a binder component (resin component) to form a film-forming composition (coating composition), which is used as a base material. It can be applied to form a particle-dispersed film, or it can be similarly incorporated into a binder component (resin component) to form a molding resin composition. Further, after removing the solvent by concentration to dryness or centrifugation, the solvent can be dried and handled as particle powder.

  There is no restriction | limiting in particular as said binder component, According to the objective, it can select suitably, For example, a silicone alkoxide type binder, an acrylic resin, a polyester resin, a fluororesin etc. are mentioned. Also, various synthetic resins and natural resins that are thermoplastic or thermosetting (including thermosetting, ultraviolet curable, electron beam curable, moisture curable, and combinations thereof) can be used. Examples of the synthetic resin include alkyd resin, amino resin, vinyl resin, acrylic resin, epoxy resin, polyamide resin, polyurethane resin, thermosetting unsaturated polyester resin, phenol resin, chlorinated polyolefin resin, silicone resin, acrylic silicone resin. , Fluorine resin, xylene resin, petroleum resin, ketone resin, rosin-modified maleic acid resin, liquid polybutadiene, coumarone resin, and the like. Examples of the natural resin include shellac, rosin (pine resin), ester gum, cured rosin, decolorized shellac, and white shellac. These may be used individually by 1 type and may use 2 or more types together.

  When the metal oxide fine particles are dispersed in the resin composition, if necessary, for example, a dispersant, an oil component, a surfactant, a pigment, a preservative, alcohol, water, a thickener, a humectant, and the like. It can be blended and used in various forms such as dilute solution, tablet, lotion, cream, paste, and stick. The dispersant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a compound having a phosphate group, a polymer having a phosphate group, a silane coupling agent, and a titanium coupling agent. It is done.

  The metal oxide fine particle dispersion of the present invention has excellent dispersion stability and is extremely transparent in the visible range and specific wavelength range, and therefore is suitably used for optical filters, paints, fibers, cosmetics, lenses and the like. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
-Preparation of metal oxide fine particle dispersion-
First, 2.1 g of tin tetrachloride pentahydrate was added to 75 ml of distilled water (solvent), and the addition amount (mol) of acid shown in Table 1 was added thereto and kept at 80 ° C. with stirring. It was. Next, a metal alkoxide solution in which an addition amount (mol) of acid shown in Table 1 with respect to 14 ml of titanium tetraisopropoxide and 12 ml of ethanol (however, oxalic acid was dissolved in 36 ml of ethanol) was added. Was added to the solvent over 5 minutes, followed by reaction for 30 minutes and cooling. 1-No. Sixteen Sn-Ti composite metal oxide fine particle dispersions were prepared.
As a result of the X-ray diffraction (XRD) spectrum analysis of the obtained metal oxide fine particles measured as follows, the rutile structure was the majority.
<Measurement of X-ray diffraction (XRD) spectrum>
The measurement was performed at 23 ° C. using “RINT 1500” (X-ray source: copper Kα ray, wavelength 1.5418 mm) manufactured by Rigaku Corporation.

  Next, for each of the obtained metal oxide fine particle dispersions, the transparency immediately after preparation of the dispersion, the transmittance of 800 nm, the average primary particle size (TEM), and the average particle size (dynamic scattering) are as follows. And stability over time were evaluated. The results are shown in Table 1.

<Transparency immediately after preparation of dispersion>
Each dispersion was prepared, and the transparency immediately after cooling to room temperature was evaluated by visual observation based on the following criteria.
〔Evaluation criteria〕
○: Transparent △: Slightly cloudy ×: Cloudy

<Measurement of average primary particle size (TEM)>
The average primary particle size of each metal oxide fine particle dispersion was measured by “H-9000UHR transmission electron microscope” (acceleration voltage 200 kV, vacuum degree 7.6 × 10 ⁻⁹ Pa at observation) manufactured by Hitachi, Ltd. The equivalent circle diameter was measured for 300 particles and indicated by the volume average diameter.

<Measurement of average particle size (dynamic scattering)>
The average particle diameter of each metal oxide fine particle dispersion was measured using an ultrasensitive nano particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., UPA-UT151).

<Measurement of light transmittance>
About each metal oxide fine particle dispersion, the light transmittance in optical path length 10mm and wavelength 800nm was measured with the apparatus "UV-3100" (made by Shimadzu Corporation) for ultraviolet visible absorption spectrum measurement.

<Stability over time>
The transparency after each metal oxide fine particle dispersion was allowed to stand at room temperature for 1 week was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
○: No change △: There is sedimentation ×: There is much sedimentation

(Example 2)
No. of Example 1 No. 3 in Example 1 except that the solvent temperature was changed from 80 ° C. to 35 ° C. In the same manner as in Example 3, a Sn—Ti composite metal oxide fine particle dispersion was prepared.
For the obtained dispersion, the transparency immediately after preparation of the dispersion, the transmittance of 800 nm, the average primary particle size (TEM), the average particle size (dynamic scattering), and the stability over time were obtained in the same manner as in Example 1. evaluated. The results are shown in Table 2.

(Example 3)
No. of Example 1 No. 3 in Example 1 except that the solvent temperature was changed from 80 ° C. to 35 ° C. In the same manner as in Example 3, a Sn—Ti composite metal oxide fine particle dispersion was prepared.
For the obtained dispersion, the transparency immediately after preparation of the dispersion, the transmittance of 800 nm, the average primary particle size (TEM), the average particle size (dynamic scattering), and the stability over time were obtained in the same manner as in Example 1. evaluated. The results are shown in Table 2.

Example 4
No. of Example 1 No. 3 in Example 1 except that tin tetrachloride was not added to distilled water (solvent). In the same manner as in No. 3, a Ti metal oxide fine particle dispersion was prepared.
For the obtained dispersion, the transparency immediately after preparation of the dispersion, the transmittance of 800 nm, the average primary particle size (TEM), the average particle size (dynamic scattering), and the stability over time were obtained in the same manner as in Example 1. evaluated. The results are shown in Table 2.

  Since the metal oxide fine particle dispersion produced by the method for producing a metal oxide fine particle dispersion of the present invention has high transparency, it can be widely used for optical filters, paints, fibers, cosmetics, lenses, and the like. Specifically, high refractive index hard coat film of high refractive index plastic lens provided with coating film, plastic deterioration prevention additive, cosmetic additive, camera lens, automotive window glass, plasma display, EL display, liquid crystal The present invention can be widely applied to displays, high refractive index films for reading and writing of high-density recording optical media, and the like.

Claims (7)

  A method for producing a metal oxide fine particle dispersion, comprising adding a metal alkoxide solution containing at least one metal alkoxide and at least one acid compound to a solvent containing at least one acid compound.   The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the temperature of the solvent when the metal alkoxide solution is added to the solvent containing at least one acidic compound is 30 ° C or higher.   The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the acidic compound is any one of hydrochloric acid, nitric acid, and acetic acid.   The method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 3, wherein the content of the acidic compound in the metal alkoxide solution is 0.1 mol / L to 5.0 mol / L.   The method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 4, wherein the content of the acidic compound in the solvent is 0.1 mol / L to 5.0 mol / L.   A metal oxide fine particle dispersion produced by the method for producing a metal oxide fine particle dispersion according to claim 1.   The metal oxide fine particle dispersion liquid according to claim 6, wherein the metal oxide fine particles comprise a metal oxide containing one kind of metal or a composite metal oxide containing two or more kinds of metals.