JPH053407B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a monodisperse of inorganic oxide fine particles in an organic solvent. More specifically, after coupling a suspension of hydrate fine particles in an alcoholic solution obtained by the specified manufacturing method, excellent dispersion stability can be achieved by replacing the alcoholic solvent with the desired organic solvent. , relates to a method for producing an organic solvent monodispersion of organic oxide fine particles having affinity for organic solvents. This organic solvent monodispersion of inorganic oxide fine particles is
There are almost no agglomerated particles or coarse particles, and the fine particle surface has been modified, so it can be used for polymer films, fibers, sheets, etc. that require uniform dispersibility as is.
As a filler material for various molding agents and paints,
It also has industrial value, as it can be used as a surface treatment material for glass, plastic, ceramics, etc. (Prior art) Conventional methods for surface modification of hydrophilic inorganic oxide fine particles include adsorption of surfactants or treatment with reactive monomers or coupling agents that can react with metal hydroxyl groups on the surface of the fine particles. It is practiced more than ever. The method using a surfactant is a method in which a surfactant is added to an aqueous suspension of fine particles and adsorbed onto the surface of the fine particles, and has the drawback that the surface modification effect is generally weak. On the other hand, in the method using a coupling agent, the coupling agent is added when the powdered fine particles are suspended in an organic solvent, or the coupling agent is added after replacing the water solvent with an organic solvent in an aqueous dispersion of fine particles. Since this method involves modifying the surface of the particles by modifying the surface of the particles, agglomeration of the particles is unavoidable, and it has therefore been impossible to obtain an organic solvent dispersion in which the particles are monodispersed. On the other hand, it is known that a suspension of hydrate fine particles can be obtained by hydrolyzing a hydrolyzable organometallic compound such as a metal alkoxide in an alcoholic solution. However, since this suspension contains catalyst components and water, and the type of alcohol is limited, the suspension cannot be used as is for various purposes. Therefore, it is recommended to separate the hydrate particles from this suspension by distilling off the alcohol solvent or by centrifugation, and then resuspending the particles in a desired organic solvent after drying and baking if necessary. However, the formation of agglomerated particles during the process was unavoidable. (Problems to be Solved by the Invention) The present invention provides a monodispersion of oxide fine particles in an organic solvent from a hydrate fine particle suspension obtained by hydrolyzing a hydrolyzable organometallic compound in an alcoholic solution. The present invention provides a method for producing a stable organic solvent monodispersion even at a high concentration of fine particles by modifying the surface of fine particles while preventing the formation of aggregated particles during the process. (Means and effects for solving the problems) As a result of intensive studies by the present inventors in order to solve the problems of the prior art described above, the present inventors have found that a hydrolyzable organometallic compound is hydrolyzed in an alcoholic solution. When producing an organic solvent monodispersion of inorganic oxide fine particles from the obtained hydrate fine particle suspension, at least the following steps are performed, namely the first step: A hydrolyzable organometallic compound is added to an aqueous alcohol solution. a step of obtaining a suspension of substantially amorphous hydrate fine particles (hereinafter referred to as hydrate fine particles (a)) in an alcoholic solution; second step; suspending the alcoholic solution; The third step is the step of adding a coupling agent into the body to perform coupling treatment; the alcoholic solvent of the alcoholic solution suspension subjected to coupling treatment is an organic solvent (hereinafter referred to as organic solvent (B)). By applying a manufacturing method including a step of replacing the solvent with the organic solvent to obtain a monodispersion of oxide fine particles in an organic solvent,
We have discovered that it is possible to suppress the agglomeration of fine particles in a dispersion and to create a fine particle surface that has a high affinity for organic substances, thereby producing a stable monodispersion of inorganic oxide fine particles in an organic solvent, which led to the present invention. It is. Hydrolyzable organometallic compounds that are raw materials for inorganic oxide fine particles (hereinafter referred to as oxide fine particles (c)) in an organic solvent monodisperse include silicon, titanium, and zirconium containing hydrolyzable organic groups. Any metal compound such as aluminum or the like that can be hydrolyzed to form a hydrate may be used, and alkoxides of the above metals are preferably used as they are industrially easily available and inexpensive. They have the general formula M(OR)
m (where M is a metal element, m is an integer corresponding to the valence of the element, and R is an alkyl group), preferably the alkyl group has 8 carbon atoms.
Lower alkyl groups up to are used. Specifically, tetramethyl silicate, tetraethyl silicate, tetraisopropyl silicate, tetrabutyl silicate, tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetramethyl zirconate, tetraethyl zirconate, tetraisopropyl zirconate, tetrabutyl. Examples include zirconate, tetra(2-ethylhexyl) titanate, trimethylaluminate, triethylaluminate, triisopropylaluminate, tributylaluminate, etc., but compounds with different alkyl groups such as dimethyldiethylsilicate, diethyldibutyltitanate, etc. It's okay to be. Other preferred organometallic compounds include derivatives of these alkoxides. An example is a compound in which some of the alkoxide groups (OR) in the general formula M(OR)m are substituted with a group capable of forming a chelate compound, such as a carboxyl group or a β-dicarbonyl group, or a compound substituted with these alkoxides or alkylcosides. These include low condensates obtained by partially hydrolyzing . Other organometallic compounds include titanium, zircon or aluminum acylate compounds such as zirconium acetate, zirconium oxalate, zirconium lactate, titanium lactate, aluminum lactate; titanium acetylacetonate, zircon acetylacetonate, titanium octyl glycolate; Examples include glycols of titanium, zircon, or aluminum, such as titanium triethanolaminate and aluminum acetylacetonate, and chelate compounds such as β-diketones, hydroxycarboxylic acids, ketoesters, ketoalcohols, aminoalcohols, and quinolines. The oxide fine particles (c) are mainly made from the above-mentioned organometallic compounds of silicon, titanium, zirconium and/or aluminum, but also contain sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, By coexisting organometallic compounds or inorganic salts such as barium, boron, gallium, indium, tin, iron, copper, etc., and hydrolyzing them, oxides of silicon, titanium, zirconium, and/or aluminum and oxides of the above metals can be combined. It can also be made into composite fine particles. At this time, the proportion of silicon, titanium, zirconium and/or aluminum oxide in the oxide fine particles is not particularly limited, but is preferably 70% or more. In the present invention, in order to obtain a monodispersion of inorganic oxide fine particles in an organic solvent, the above organometallic compound is first hydrolyzed and condensed in an alcoholic solution to obtain a suspension of hydrate fine particles in an alcoholic solution (hereinafter referred to as (referred to as the first step). At this time, there is no restriction on the final concentration of the organometallic compound in the solution, but if the concentration is 2 mol/less or less, aggregation of the generated hydrate fine particles is less likely to occur, and therefore, the final concentration disclosed in the present invention is When an organic solvent dispersion of oxide fine particles is prepared by the method described above, there are no agglomerated particles, which is preferable. The alcohol in the alcoholic solution is not particularly limited, and various types can be used. For example, methanol, ethanol, isopropanol, butanol, isoamyl alcohol, ethylene glycol, propylene glycol, etc. are used alone or in mixtures. Further, a portion of an organic solvent such as dioxane, diethyl ether, ethyl acetate, benzene, toluene, hexane, etc. can be mixed into the solution. Water necessary for hydrolysis is allowed to coexist in the alcoholic solution. This water content affects the shape and diameter of the particles, so it needs to be controlled to a preferable amount, but it changes depending on the type of metal and compound of the organometallic compound. This water can also be supplied by moisture in the gas phase. Hydrolysis can be carried out, for example, by adding the above-mentioned organometallic compound raw material or its alcoholic solution into the above-mentioned alcoholic solution and stirring at a temperature of 0 to 100°C, preferably 0 to 50°C for 10 minutes to 100 hours. It is done by folding. At that time, catalyst components such as cations such as NH ₄ ⁺ and Na ⁺ and anions such as SO ₄ ^2- and H ₂ PO ₄ ^- can be added in order to control the hydrolysis rate, but their presence or absence and amount varies depending on the raw material, and is appropriately selected in consideration of the influence on particle shape and particle size. By hydrolyzing the organometallic compound in an alcoholic solution under appropriate conditions in this way, a monodisperse suspension of hydrate fine particles (a) can be obtained. Furthermore, by selecting preferable conditions such as raw material concentration, reaction temperature, water concentration, type of alcohol and solvent, type and concentration of catalyst, etc., hydrate fine particles (a) are spherical and have an average particle size in the range of 0.05 to 5 μm. The particle size can be controlled to any desired size, and the standard deviation value of the particle size is 1 to 1.
In the range of 1.5, 1 to 1 depending on the selection of preferable conditions.
It is possible to obtain uniform particles in the range of 1.3. Hydrate fine particles controlled in this manner are particularly preferred when used as various fillers or surface treatment agents. A coupling agent is added to the thus produced suspension of hydrate fine particles (a) in an alcoholic solution to subject the surfaces of the fine particles to a coupling treatment (hereinafter referred to as the second step). On the surface of the hydrate fine particles (a) obtained in the first step, some of the organic groups derived from the raw materials remain and are bonded, and the catalyst components are adsorbed, so the particle surface is easily changed. It is active. When the alcoholic solvent is distilled from the suspension obtained in the first step without treatment, the formation of aggregated particles is observed, but the reason for this is that the hydrolysis reaction on the particle surface progresses. This is thought to be due to the surface condition changing to a form that makes aggregation more likely, such as desorption of adsorbed components. As a result of various studies on methods for controlling the activity of the particle surface, the present inventors found that the surface of hydrate fine particles (a) has a high reactivity with a coupling agent, and if coupling treatment is performed after the first step, the coupling agent can be used. They have discovered that even in small amounts, they have an excellent effect of preventing agglomeration of fine particles and can convert the surface of fine particles to have affinity for organic solvents. Coupling agents that can be used in the present invention are not particularly limited as long as they have one or more non-hydrolyzable organic groups and one or more hydrolyzable groups in the molecule, but those that are easily available can be used. Preferred examples include silane-based, titanate-based, and aluminum-based coupling agents. For example, methyltrimethoxysilane, phenyltrimethoxysilane, benzyltrimethoxysilane, methyltriisopropoxysilane, 3-chloropropyltrimethoxysilane, dimethoxydimethylsilane, diethoxymethylphenylsilane, ethoxytrimethylsilane, 3-amino One or more types of ( Alkoxysilanes having (substituted) alkyl group, (substituted) phenyl group, vinyl group, etc., trimethylchlorosilane,
Silane coupling agents such as chlorosilanes such as diethyldichlorosilane, acetoxysilanes such as acetoxytriethylsilane, diacetoxydiphenylsilane, and triacetoxyvinylsilane,
Examples include titanate coupling agents such as isopropyltriisosteroyl titanate and bis(dioctylpyrophosphate)oxyacetate titanate, and aluminum coupling agents such as acetalkoxyaluminum diisopropylate, but are not limited thereto. When an alkoxide or a derivative thereof is used as the organometallic compound in the first step, it is particularly preferable to use a coupling agent having an alkoxy group as a hydrolyzable group because of its high reactivity. The amount of coupling agent added is 0.1 to 10% by weight, preferably 0.1 to 10% by weight based on the weight of fine particles converted to oxide.
The range is 0.5 to 5% by weight. If it is below the lower limit, the effect will be small, and if it is above the upper limit, it will be effective but not economical. The temperature of the coupling treatment may be in the range of 0 to 100 DEG C. and is preferably carried out at the temperature in the first step. Next, the alcoholic solvent of the alcoholic solution suspension of the coupled hydrate fine particles (hereinafter referred to as hydrate fine particles (b)) is replaced with an organic solvent (B), and the oxide fine particles (c ) as an organic solvent dispersion.
(Hereinafter referred to as the third step.) The alcoholic solvent includes the alcohol used in the first step, the organic solvent, water added in excess of the hydrolysis equivalent, the catalyst, and the organic matter by-produced from the hydrolyzed organometallic compound. A solvent consisting of organic substances produced as a by-product from the reaction between a coupling agent and the particle surface. Specific methods for solvent replacement include, for example, (1) a method in which the coupled hydrate fine particles (c) are separated from the alcoholic solvent by sedimentation, centrifugation, etc., and then redispersed in the organic solvent (B). (2) A method of distilling off the alcoholic solvent from an alcoholic solution suspension of hydrate fine particles (b) in the coexistence of an organic solvent (B) to obtain an organic solvent dispersion. Any method can be used. After the third step, the organic solvent dispersion may be heat-treated to advance dehydration of the oxide fine particles (c), if necessary. The above solvent replacement method (2) does not involve solid-liquid separation,
Further, when heat treatment is performed after the third step, the same apparatus can be used, which is preferable. In that case, the boiling point of the organic solvent (B) is selected to be equal to or higher than that of the alcohol used in the first step. The operating conditions such as temperature and pressure for distilling the alcoholic solvent are not particularly limited and can be arbitrarily selected. The organic solvent (B) used includes saturated or unsaturated aliphatic hydrocarbons, aromatic hydrocarbons and their halides, monohydric and dihydric or higher alcohol compounds, ether compounds, ester compounds, amines, etc. It can be arbitrarily selected from organic compounds such as nitrogen-containing compounds, carbonyl compounds such as aldehydes and ketones, carboxylic acid compounds, and carbohydrates such as monosaccharides and polysaccharides, but those that are liquid at room temperature are preferred. Alternatively, the same alcohol as used in the first step may be used. When a monodispersion of oxide fine particles (c) in an organic solvent is used in a polymerization system, the organic solvent can be a polymerizable monomer or prepolymer depending on the purpose of use. The inorganic oxide fine particles as used in the present invention include particles that partially contain hydroxyl groups, coupling agent residues, adsorbed catalysts, and adsorbed water. In this way, a monodisperse of inorganic oxide fine particles in an organic solvent is finally obtained, but the dispersion stability is good even when the concentration of fine particles in the monodisperse is about 50% by weight in terms of oxide. be. In addition, alcoholic solvents other than the organic solvent (B) in the monodisperse are present in all solvents.
It does not matter if about 20% by weight or less remains. (Effect of the invention) The organic solvent monodispersion of inorganic oxide fine particles obtained by the specified manufacturing method has almost no aggregated particles,
As a result of the fine particle surface being compatible with organic solvents and polymers, even dispersions with a high concentration of fine particles have high storage stability, and when used, the fine particles are in a highly dispersed state, making them suitable for use as fillers for polymers, surface treatment agents, and lubricants. It is suitable for uses such as materials. (Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited by the Examples. In addition, the shape of the fine particles in the organic solvent dispersion sample of the inorganic oxide fine particles, the average particle diameter, the standard deviation value, the presence or absence of aggregated particles, the dispersion stability, the crystallinity of the fine particles produced in each process, and the adsorbed water content are It was analyzed and evaluated by the following method. ●Particle shape Determined by electron microscope observation at 50,000x magnification. ●Average particle diameter and standard deviation value: 100 arbitrary particles in an electron microscope image taken at 50,000 times magnification
The particle diameter of each particle was actually measured and calculated using the following formula. Standard deviation value = X + σ _o-1 /X (However, ) ●Presence or absence of aggregated particles The sample was observed and evaluated in the slurry state using an optical microscope at 1000x magnification. ●Dispersion stability Place the sample in a tightly closed glass container and let it stand.
The presence or absence of a particle sedimentation layer at the bottom of the container and a supernatant layer at the top was observed and evaluated based on the following criteria. Items in which a sedimentation layer or supernatant layer was observed after standing for 1 day × Items in which a sedimentation layer or supernatant layer was observed after standing for 2 days to 1 month 〇A sedimentation layer or supernatant layer was observed even after 1 month What is not there
◎ ●Crystallinity of fine particles After repeating centrifugation, washing with absolute ethanol, and centrifugation of a part of the suspension or dispersion, vacuum dry at 50°C to obtain a powder sample. The crystallinity of the fine particles of the powder sample was evaluated by X-ray diffraction. ●Adsorbed water content A powder sample obtained in the same manner as above was weighed in a porcelain container (the weight of the sample at that time is Ag), and then placed in an oven at 200℃ with dry air flowing through it for 5 hours. Hold. After cooling, the container was weighed (the sample weight at that time was taken as Bg), and the adsorbed water content in the fine particles was measured using the following formula. Adsorbed water content = A-B/A x 100 (%) Example of manufacturing a suspension of hydrate fine particles in an alcoholic solution 1-(1) 30 glass reactors equipped with a stirrer, a dropping port, and a thermometer 16 kg of methanol and 1.5 kg of 28% aqueous ammonia solution were added and mixed. The mixture was heated to 20°C.
While adjusting the temperature to ±0.5°C and stirring, a solution of 1.0 kg of tetramethyl silicate diluted in 2 methanol was added dropwise from the dripping port over 1 hour. After dropping, stirring was continued for 2 hours to perform hydrolysis and form silica hydrate fine particles. An alcoholic solution suspension of (1a) was produced.
At this time, the concentrations of each raw material relative to the total amount of the final solution were 0.32 mol/tetramethylsilicate, 2.90 mol/water, and 1.19 mol/ammonia. Table 1 shows the reaction conditions and particle analysis results. Example 1-(2) to (7) Same as Example 1-(1) except that the type of organometallic compound, the type of alcohol, the concentration of each raw material with respect to the total amount of the final solution, and the reaction temperature are as shown in Table-1. Similarly, a suspension of Arica hydrate fine particles (2a) to (3a), a suspension of titania hydrate fine particles (4a),
A suspension of zirconia hydrate fine particles (5a), a suspension of alumina hydrate fine particles (6a), and a suspension of silica-alumina composite hydrate fine particles (7a) were produced. Table 1 shows the reaction conditions and analysis results.

[Table] Production example of organic solvent monodispersion of inorganic oxide fine particles 2-(1)' Silane coupling to 16.7 kg of suspension of silica hydrate fine particles (1a) produced in Example 1-(1) 2.0 g of phenyltrimethoxysilane (0.5 g based on the weight of silica hydrate fine particles converted to oxide) as an agent.
% by weight) and stirred at room temperature for 30 minutes to perform a silane coupling treatment, and then 1.2 kg of ethylene glycol was mixed as an organic solvent to obtain an organic solvent-containing suspension. Next, there is a glass evaporator (5) equipped with a stirrer that can heat the heat medium from the outside, a dripping port, a thermometer, and a distilled gas outlet, and following the distilled gas outlet, a distilled gas condenser, a vacuum suction port, First, two of the organic solvent-containing suspensions are charged into an evaporation pot of an evaporation device consisting of a condensate receiver, and heated while maintaining the pressure in the system at 200 Torr to distill out the alcoholic solvent and to remove the suspension. The remainder of the turbidity was continuously supplied, heating was continued even after the supply was completed, and solvent distillation was stopped when the internal temperature reached 100°C. In this way, an organic solvent (ethylene glycol) dispersion of silica fine particles (1c) was produced. This dispersion contained 11% by weight of an alcoholic solvent (mainly methanol and water) in the solvent excluding the fine particles. Table 2 shows the silane coupling treatment conditions and solvent replacement conditions, and Table 3 shows the properties of the dispersion and the analysis values of the fine particles. Example 2-(2) to (7) Each hydrate fine particle (2a) produced in Example 1-(2) to (7)
In the method of Example 2-(1) using the alcoholic solution suspension of ~(7a), the type of coupling agent,
Oxide fine particles (2c) ~
An organic solvent dispersion of (7c) was produced. Display the results -
2 and Table 3. Comparative Example Solvent replacement was carried out in the same manner as in Example 2-(2) except that the coupling treatment was not performed in Example 2-(2).
The results are shown in Table 3.

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Claims (1)

[Claims] 1. When producing an organic solvent monodispersion of inorganic oxide fine particles from a hydrate fine particle suspension obtained by hydrolyzing a hydrolyzable organometallic compound in an alcoholic solution, Both of the following steps, namely the first step; a step of hydrolyzing a hydrolyzable organometallic compound in an aqueous solution of alcohol to obtain a suspension of hydrate fine particles in an alcoholic solution; a second step; A step of adding a coupling agent to the alcoholic solution suspension to perform a coupling treatment; a third step; replacing the alcoholic solvent of the alcoholic solution suspension subjected to the coupling treatment with an organic solvent; 1. A method for producing a monodisperse of inorganic oxide particles in an organic solvent, the method comprising the step of obtaining a monodisperse of oxide particles in an organic solvent. 2. A patent characterized in that the organometallic compound is mainly composed of a compound of silicon, titanium, zirconium, and/or aluminum, and the inorganic oxide fine particles are mainly composed of silica, titania, zirconia, alumina, or a composite oxide thereof. The method according to claim 1. 3. The method according to claim 1 or 2, wherein the organometallic compound is an alkoxide or a derivative thereof. 4. The method according to claim 1, 2 or 3, wherein the coupling agent is a silane-based, titanate-based and/or aluminum-based coupling agent. 5 The inorganic oxide fine particles are spherical and the average particle size is
5. The method according to claim 1, wherein the particle diameter is in the range of 0.05 to 5 μm and the standard deviation value of the particle diameter is in the range of 1 to 1.5.