JP4305612B2 - Metal oxide ultrafine particles and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to metal oxide ultrafine particles and a method for producing the same.
[0002]
[Prior art]
In metal oxide ultrafine particles of 100 nm or less, it is known that the properties of metal oxides are significantly different from those of general particle sizes. For example, since the surface area per unit volume is large, high catalytic activity and the like are exhibited. In addition, since the sintering temperature is lower than that of the bulk material, tin oxide, indium oxide, and the like known as conductive oxides are expected as materials for forming a large-area transparent conductive film.
[0003]
As a method for producing such metal oxide fine particles, a pulverization method in which large solid particles are crushed into fine particles has been widely used industrially. However, the size at the sub-micron level is the limit, and for producing metal oxide ultrafine particles, it is necessary to rely on a gas phase method or a liquid phase method capable of designing particles at the nano level.
[0004]
As the vapor phase method, the raw material metal is heated to evaporate and agglomerated in an inert atmosphere gas such as argon or helium to produce ultrafine particles of metal oxide, metal chloride with high vapor pressure, There are gas phase reaction methods in which volatile oxychlorides, metal alkoxides, organometallic compounds and the like are used as raw material compounds and thermally decomposed at high temperatures. However, in the evaporation condensation method, expensive argon, helium, etc. must be used, which is very disadvantageous in terms of cost. In the gas phase reaction method, the raw material compound has high reactivity, is difficult to handle, and has problems in terms of handleability and safety.
[0005]
In addition, these manufacturing methods employ a resistance heating method, an electric furnace method, a high-frequency induction heating method, a plasma heating method, an electron beam heating method, a laser beam heating method, etc. as a heating method. is required.
[0006]
On the other hand, the liquid phase method includes a chemical precipitation method in which solid particles are precipitated from a metal salt aqueous solution or metal alkoxide by a chemical reaction, and an alkoxide that obtains silica colloid or titanium oxide metal oxide ultrafine particles from hydrolysis and polycondensation reaction of metal alkoxide. And hydrothermal synthesis using high-temperature and high-pressure hydrothermal conditions. However, in any method, the aggregation of the generated particles becomes a problem.
[0007]
On the other hand, there is also a method of synthesizing fine particles such as zirconium oxide and titanium oxide by spray pyrolysis method in which a metal salt solution is sprayed in a high temperature atmosphere and solvent evaporation and metal salt pyrolysis are performed in one step to synthesize powder. . However, this method is often obtained in the form of hollow particles or crushed particles thereof. For this reason, in order to obtain solid metal oxide ultrafine particles, sintering and melting at higher temperatures are required.
[0008]
Thus, in the prior art, it is difficult to efficiently produce metal oxide ultrafine particles, and the obtained metal oxide ultrafine particles still have problems in physical properties in terms of aggregation and the like.
[0009]
[Problems to be solved by the invention]
In view of the current situation as described above, development of a new technology is required for producing ultrafine metal oxide particles having excellent dispersion stability on an industrial scale.
[0010]
Accordingly, the main object of the present invention is to produce ultrafine metal oxide particles having excellent dispersion stability on an industrial scale.
[0011]
[Means for Solving the Problems]
As a result of intensive studies in view of the above-described problems of the prior art, the present inventor has found that the metal oxide ultrafine particles obtained by a specific production method develop a unique property based on its unique configuration. The present invention has been completed.
[0012]
That is, the present invention relates to the following metal oxide ultrafine particles and a method for producing the same.
[0016]
1. A method for producing a powder comprising ultrafine metal oxide particles, wherein a powdered or liquid metal organic compound is heated in an oxidizing atmosphere to a temperature not less than the decomposition start temperature of the organic component of the metal organic compound and less than 400 ° C. method was heated at a temperature, containing a metal oxide and an organic component, characterized in that said metal oxide to obtain a fine particle containing 50 to 95 wt%.
2. The manufacturing method of said claim | item 1 whose heating temperature is 200 degreeC or more and less than 400 degreeC.
3. Item 3. The method according to Item 1 or 2, wherein the metal organic compound is a metal salt of a fatty acid.
4). Item 4. The method according to Item 3, wherein the fatty acid has 5 to 30 carbon atoms.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(1) Metal oxide ultrafine particles of the present invention The metal oxide ultrafine particles of the present invention are fine particles containing a metal oxide and an organic component and have an average particle diameter of 1 to 100 nm.
[0021]
In the present invention, the organic component is not particularly limited as long as the dispersion stability of the present invention can be maintained. In particular, an organic component derived from a metal organic compound is preferable. That is, as shown in the production method of the present invention described later, an organic component remaining when the metal organic compound is heated under predetermined conditions is preferable.
[0022]
Examples of the metal organic compound as described above include metal alkoxide and the like in addition to the organic metal compound. The metal organic compound is not particularly limited, and any commercially available product can be used. For example, carboxylic acids represented by naphthenate, octylate, stearate, general formula C ₆ H ₅ (CH ₂ ) _n COOH (n is preferably an integer of 0 to 5) (for example, benzoic acid, etc.) Salts, fatty acid metal salts such as p-toluoylate and n-decanoate, metal alkoxides such as isopropoxide and ethoxide, and acetylacetone complex salts of the above metals. Among these, oleate, p-toluate, stearate, n-decanoate, metal ethoxide, metal acetylacetonate and the like are particularly preferable.
[0023]
Of these, fatty acid salts (metal salts of fatty acids) are preferred. In particular, metal salts of saturated fatty acids are desirable. As the saturated fatty acid, for example, the following general fatty acids are suitable.
[0024]
C _n H _{2n + 1} COOH (where n represents an integer of 5 to 30)
The n (the number of carbon atoms of the fatty acid) is not limited, but is usually about 5 to 30, particularly 5 to 20, and further preferably 6 to 18.
[0025]
The metal contained in the metal organic compound is not particularly limited, and can be appropriately selected according to the use of the metal oxide ultrafine particles. Preferably Cu, Zn, In, Si, Ge, Sn, Fe, Co, Ni, Ru, Rh, Os, Ir, V, Cr, Mn, Y, Ti, Zr, Nb, Mo, Ca, Ba, Sb and A metal organic compound containing at least one of Bi can be preferably used.
[0026]
Moreover, a metal organic compound can be used individually or in combination of 2 or more types. The metal of the metal organic compound is not particularly limited, and can be appropriately selected according to the use of the final product.
[0027]
The metal component is not particularly limited as long as it is derived from the metal organic compound. That is, any metal component that exists in the metal organic compound used may be used. The metal component is preferably Cu, Zn, In, Si, Ge, Sn, Fe, Co, Ni, Ru, Rh, Os, Ir, V, Cr, Mn, Y, Ti, Zr, Nb, Mo, Ca. , Ba, Sb and Bi. The metal component of the present invention includes all states such as a single metal, a mixture of these metals, or an alloy of these metals.
[0028]
The ratio of the metal oxide component in the ultrafine metal oxide particles of the present invention can be appropriately set according to the use of the final product, but is usually about 50 to 95% by weight, preferably 60 to 95% by weight. . The balance may contain components other than organic components, but it is desirable that the balance is substantially composed of organic components.
[0029]
The average particle diameter of the metal oxide ultrafine particles is usually about 1 to 100 nm, but can be changed depending on the use of the final product. For example, when used for metal coating, it is usually about 1 to 50 nm, preferably 1 to 10 nm.
(2) Method for Producing Metal Oxide Ultrafine Particles The metal oxide ultrafine particles of the present invention have, for example, a metal organic compound that is not less than the decomposition start temperature of the metal organic compound and less than the complete decomposition temperature in an oxidizing atmosphere. It can manufacture by heating within a temperature range.
[0030]
The type of the metal organic compound is not particularly limited, and those mentioned in the above (1) can be used. Among these, carboxylic acids (for example, benzoate) represented by oleate, p-toluate, stearate, and general formula C ₆ H ₅ (CH ₂ ) _n COOH (n is preferably an integer of 0 to 5). Acid) salt, n-decanoate, metal ethoxide, metal acetylacetonate and the like are preferable. More preferred are the fatty acid salts mentioned in (1) above. That is, as the above fatty acid, the following general fatty acids are suitable.
[0031]
C _n H _{2n + 1} COOH (where n is an integer of 5 to 30)
The n (the number of carbon atoms of the fatty acid) is not limited, but is usually about 5 to 30, particularly 5 to 20, and further preferably 6 to 18.
[0032]
Regarding the metal component of the metal organic compound, for example, when the metal oxide ultrafine particles obtained from the metal organic compound are used for a metal coating film, the metal component mainly forms a metal coating film. May be selected as appropriate.
[0033]
For example, even a metal organic compound having properties such as sublimability and rapid decomposition can be effectively used by adding a high-boiling solvent to suppress sublimation.
[0034]
In the method of the present invention, it is also possible to prepare composite type metal oxide ultrafine particles by previously mixing, for example, a metal organic compound containing two or more metals.
[0035]
The form of the metal organic compound as a raw material is not particularly limited, and any form such as powder or liquid may be used.
[0036]
The heating temperature is not particularly limited as long as the metal organic compound is not completely decomposed. In other words, the temperature may be within the temperature range above the decomposition start temperature of the metal organic compound and below the complete decomposition temperature. The decomposition start temperature is a temperature at which the organic component of the metal organic compound begins to decompose, and the complete decomposition temperature is a temperature at which the organic component of the metal organic compound is completely decomposed. In this invention, it can set suitably according to the kind etc. of a metal organic compound within this temperature range. For example, in the case of a metal organic compound having a decomposition start temperature of about 200 ° C. and a complete decomposition temperature of about 400 ° C., the heating temperature may be maintained within a temperature range of 200 ° C. to 400 ° C. The holding time can be changed as appropriate according to the heating temperature and the like.
[0037]
The upper limit of the heating temperature is particularly preferably set at the temperature at which the metal organic compound to be used is thermally decomposed and its weight is reduced to 50% of the original.
[0038]
The heating atmosphere may be an oxidizing atmosphere, and may be, for example, in the air or in an oxygen gas atmosphere. Moreover, you may dilute with inert gas, such as nitrogen, a carbon dioxide, argon, and helium.
[0039]
Moreover, when heating, various alcohols can also be added to a metal organic compound. Thereby, the effect that the heating temperature can be lowered is obtained. Alcohols are not particularly limited as long as at least the above effects are obtained, and examples thereof include glycerin, ethylene glycol, and lauryl alcohol. The amount of alcohol added can be appropriately determined according to the type of alcohol used, etc., but is usually about 5 to 20 parts by weight, preferably 10 to 15 parts by weight with respect to 100 parts by weight of the metal organic compound. good.
[0040]
Further, in the production method of the present invention, in addition to these components, work can be performed by blending various known additives such as liquid paraffin, various petroleum-based high-boiling solvents, fats and oils, etc. within a range not impeding the effects of the present invention. It is possible to improve the sex and the like.
[0041]
After the heating is completed, purification is performed as necessary. As a purification method, a known purification method can be applied. For example, centrifugation, membrane purification, solvent extraction and the like may be performed.
[0042]
【The invention's effect】
In the production method of the present invention, metal oxide ultrafine particles different from conventional ultrafine particles can be efficiently obtained, particularly by heat-treating a metal organic compound at a relatively low temperature under a constant atmosphere.
[0043]
That is, since the metal oxide ultrafine particles of the present invention contain an organic component together with the metal oxide, the metal oxide ultrafine particles are excellent in dispersion stability and become solubilized when dispersed in a solvent. For example, it may be used as it is by dispersing in toluene, hexane, kerosene, etc., or it may be blended with a known pasting agent and used as a paste.
[0044]
The metal oxide ultrafine particles of the present invention having such characteristics have excellent characteristics (catalytic activity, conductivity, translucency, ultraviolet shielding, heat ray shielding, antibacterial, antibacterial properties) depending on the type of metal oxide. Dirty, rustproof, anticorrosive, etc.) can be obtained. For this reason, electronic materials (printed wiring, conductive materials, transparent films, optical elements, etc.), magnetic materials (magnetic recording media, electromagnetic wave absorbers, electromagnetic wave resonators, etc.), catalyst materials (fast reaction catalysts, sensors, etc.), structures It can be widely used for various applications such as materials (far infrared materials, composite film forming materials, etc.), ceramics / metal materials (sintering aids, coating materials, etc.), medical materials and the like.
[0045]
【Example】
Hereinafter, examples will be shown to further clarify the features of the present invention. Each physical property in the examples was measured as follows.
(1) Qualitative analysis The metal oxide was identified by a powder X-ray diffraction analysis method using a powerful X-ray diffractometer "MXP18" (manufactured by Mac Science).
[0046]
The organic group was identified by measuring an H1-NMR spectrum (solvent: deuterated chloroform CDCl ₃ solvent) using an NMR measuring apparatus “JOEL JNM-EX270FT-NMR” (manufactured by JEOL Ltd.).
(2) Average particle size The average particle size was determined by observing with a transmission electron microscope “JEM1200EX” (manufactured by JEOL Ltd.), and the arithmetic average value of the particle sizes of 100 particles arbitrarily selected.
(3) Content of metal component It was determined by TG / DTA analysis using a thermal analyzer “SSC / 5200” (Seiko Electronics Industry).
[0047]
Example 1
Tin myristate (C ₁₃ H ₂₇ COO) ₂ Sn (10 g) was placed as a solid in a four-necked flask and gradually heated to 300 ° C. while supplying air. After holding at 300 ° C. for 8 hours, it was allowed to cool. The produced powder was repeatedly washed with ethanol, filtered with a Kiriyama funnel, and dried under reduced pressure.
[0048]
The obtained powder was subjected to powder X-ray diffraction analysis, NMR analysis, TEM observation and thermal analysis. The result of the powder X-ray diffraction analysis is shown in FIG. The observation result (image figure) by TEM is shown in FIG. The obtained powder was identified as tin oxide (SnO ₂ ) by XRD, and the average particle diameter was 10 nm from TEM. The content of the metal oxide component was 80.3% from TG / DTA analysis, and it was found that the organic component coexists. For the organic component, signals attributable to methylene and methyl groups of the alkyl chain were observed from NMR to 0.5 to 1.5 ppm.
[0049]
Example 2
Tin decanoate (C ₉ H ₁₉ COO) ₂ Sn (10 g) was placed as a solid in a four-necked flask and gradually heated to 270 ° C. while supplying air. After holding at 270 ° C. for 8 hours, the mixture was allowed to cool. The produced powder was repeatedly washed with ethanol, filtered with a Kiriyama funnel, and dried under reduced pressure.
[0050]
The obtained powder was identified as tin oxide (SnO ₂ ), and the average particle size was 8 nm. The content of the metal oxide component was 72.1% by weight, and signals of methylene and methyl groups in the alkyl chain were observed at 0.5 to 1.5 ppm.
[0051]
Example 3
Indium myristate (C ₁₃ H ₂₇ COO) ₃ In (10 g) was placed as a solid in a four-necked flask and gradually heated to 320 ° C. while supplying air. After holding at 320 ° C. for 5 hours, it was allowed to cool. The produced powder was repeatedly washed with ethanol, filtered with a Kiriyama funnel, and dried under reduced pressure.
[0052]
The obtained powder was subjected to powder X-ray diffraction analysis, NMR analysis, TEM observation and thermal analysis. The result of the powder X-ray diffraction analysis is shown in FIG. The observation result (image figure) by TEM is shown in FIG. The resulting powder was identified as indium oxide (In ₂ O ₃ ). The average particle size was 20 nm. The content of the metal oxide component was 91.6 wt% by thermal analysis, and signals of methylene and methyl groups in the alkyl chain were observed as the organic component from 0.8 to 1.6 ppm from NMR.
[0053]
Example 4
Indium decanoate (C ₉ H ₁₉ COO) ₃ In (10 g) is placed in a four-necked flask as a solid, and is completely melted by heating to 100 ° C. while supplying air, and then gradually increased to 340 ° C. Heated. After holding at 340 ° C. for 8 hours, it was allowed to cool. The produced powder was repeatedly washed with ethanol, filtered with a Kiriyama funnel, and dried under reduced pressure.
[0054]
The resulting powder was identified as indium oxide (In ₂ O ₃ ). Moreover, the average particle diameter was 26 nm. As the organic component content of the metal oxide component was 96.6% by weight, signals of methylene and methyl groups of the alkyl chain were observed from NMR to 0.8 to 1.6 ppm.
[0055]
Example 5
Zinc decanoate (C ₉ H ₁₉ COO) ₂ Zn (10 g) was placed as a solid in a four-necked flask and gradually heated to 320 ° C. while supplying air. After holding at 320 ° C. for 8 hours, it was allowed to cool. The produced powder was repeatedly washed with methanol, filtered off with a Kiriyama funnel, and dried under reduced pressure.
[0056]
The obtained powder was identified as zinc oxide (ZnO) from powder X-ray diffraction analysis. The average particle size was 85 nm. The content of the metal oxide component was 95.1% by weight. Since signals of methylene and methyl groups in the alkyl chain were observed from 0.5 to 1.5 ppm in NMR, it was found that they coexist as organic components.
[Brief description of the drawings]
1 shows the results of powder X-ray diffraction analysis of the powder obtained in Example 1. FIG.
FIG. 2 is an image diagram showing the observation results of the powder obtained in Example 1 by TEM.
3 shows the results of a powder X-ray diffraction analysis of the powder obtained in Example 3. FIG.
4 is an image view showing the observation results of the powder obtained in Example 3 by TEM. FIG.

Claims (4)

A method for producing a powder comprising ultrafine metal oxide particles, wherein a powdered or liquid metal organic compound is heated in an oxidizing atmosphere to a temperature not less than the decomposition start temperature of the organic component of the metal organic compound and less than 400 ° C. method was heated at a temperature, containing a metal oxide and an organic component, characterized in that said metal oxide to obtain a fine particle containing 50 to 95 wt%. The manufacturing method of Claim 1 whose heating temperature is 200 degreeC or more and less than 400 degreeC. The method according to claim 1 or 2, wherein the metal organic compound is a metal salt of a fatty acid. The method according to claim 3, wherein the fatty acid has 5 to 30 carbon atoms.

Images