JPH02233505A - Production of ultrasonic powder of metal oxide composition - Google Patents

Abstract

PURPOSE:To reduce the particle diameter of a metal oxide by separately adding two or more kinds of different metal alkoxides to a W/O-type micro-emulsion consisting of a surfactant-water or a catalyst aqueous solution-nonpolar organic liquid and hydrolyzing the alkoxides. CONSTITUTION:A soluble W/O-type micro-emulsion is produced by mixing (A) an aqueous solution produced by adding 0.1-10mol/kg of water or a catalyst such as sulfuric acid to a nonpolar organic liquid such as cyclohexane and (B) 0.01-1mol/kg of a water soluble or oil-soluble surfactant of formula I-II (R' is 6-12C alkyl, etc.; M is alkali metal, etc.), etc. The oil-soluble surfactant is used as it is and the water-soluble surfactant is used as a mixture with an alcohol (having 1-20C alkyl group). A metal alkoxide such as Zr alkoxide is added to and hydrolyzed in the above micro-emulsion and a sintering stabilizer consisting of one or more kinds of metal alkoxides of Ca, Mg or lanthanide element such as Y is added to the above product in an amount of 0.1-30mol% based on the metal to be stabilized. The metal alkoxide is hydrolyzed to obtain ultrafine particle of metal oxide composition having particle diameter of <=1,000Angstrom and containing uniformly dispersed stabilizer particles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing ultrafine metal oxide particles, particularly ultrafine zirconium oxide particles that are suitably used as raw materials for zirconia ceramics.

[Prior art]

Conventionally, zirconia fine particles have been produced by neutralizing an aqueous solution containing a water-soluble zirconium salt such as zirconium nitrate, zirconium sulfate, or zirconium oxychloride with aqueous ammonia to form a precipitate of zirconium hydroxide. A method of drying and calcining after filtering and washing with water, or a method of heating and hydrolyzing an aqueous solution of a water-soluble zirconium salt to generate a sol, and drying and calcining the sol are known. In this case, the zirconia fine powder contains calcium, magnesium, yttrium, etc. as stabilizers.
Alternatively, it is recommended to include an oxide of a lanthanide element such as cerium, but such a stabilizer can be added to zirconia by adding a salt of the above metal to an aqueous solution of a water-soluble zirconium salt, or by adding a salt of the above metal to an aqueous solution of a water-soluble zirconium salt. This is done by adding salts or oxides of oxides during the calcination stage (Japanese Unexamined Patent Publication No. 185821/1983). The zirconia fine powder obtained in this way can be sintered and used as zirconia-based ceramics, but after obtaining a hydroxide or oxide sol by the above conventional method, it can be dried. The agglomerated particles of the powder are difficult to loosen and cannot be easily made into fine powder. If this powder is used as a raw material for ceramics as it is, it will have a negative effect on formability and sinterability, making it impossible to produce a fully satisfactory sintered body. There were drawbacks.

In order to obtain a stabilized zirconia sintered body, it is necessary to uniformly disperse the stabilizer and form a solid solution, but the zirconia fine powder obtained by conventional methods is not fully satisfactory in this respect.

Conventionally, in order to satisfy the requirements for zirconium oxide as a raw material for ceramics, a method has been proposed to reduce the amount of hydroxide in the hydrolysis product as much as possible (Japanese Patent Laid-Open No. 58-79818
), method using an organic solvent to prevent agglomeration during drying (Japanese Patent Publication No. 54-25523), zirconium salt alone,
or zirconium salt and magnesium, calcium and 3
A method using a spray dryer (Japanese Unexamined Patent Publication No. 60-86025) has been proposed as a method for drying an aqueous solution consisting of at least one salt selected from metal elements having a valence higher than that of the metal element, but this method is not necessarily satisfactory. It's not a kimono.

In addition, as a recent trend, improvements in the properties of high-performance ceramics, as well as quantitative control of their properties, are required, and organic polymer binders are being used as molding agents in place of sintering aids. Auxiliary agents (forming agents, sintering agents, stabilizers) added to aggregates (main component oxides) during high-temperature sintering, etc.
There is a movement to reduce this and increase the purity of sintered bodies. Furthermore, to improve sinterability, powders with small particle sizes and a sharp particle size distribution are required. [Objective] The object of the present invention is to provide a method for producing fine zirconium oxide particles that satisfy the above conditions and enable production of excellent zirconia ceramics with high density and high strength.

〔composition〕

As a result of intensive research to achieve the above object, the inventors of the present invention have found that ultrafine metal oxide particles are produced by the hydrolysis reaction of metal alkoxides in a W/O type microemulsion consisting of a surfactant, water, and nonpolar organic liquid. In the method for producing the composition, two or more different metal alkoxides are individually added at different times to a W/O microemulsion in which water or an aqueous catalyst solution is solubilized, and a hydrolysis reaction is carried out. It has been discovered that an ultrafine particulate metal oxide composition that meets the above objectives can be obtained.

By the method of the present invention, an ultrafine particulate zirconium oxide composition that is suitably used as a raw material for zirconia ceramics can be obtained. The ultrafine particulate zirconium oxide composition obtained by the method of the present invention has an oxide of at least one metal selected from calcium, magnesium, yttrium, and lanthanide elements uniformly dispersed in the vicinity of the particle surface in particle units. Contains particles with a particle size of 1,0
00 or less, preferably 300 or less.

As a method for producing metal oxide fine particles by a hydrolysis reaction of a metal alkoxide in a W/○ type microemulsion, there is a method disclosed in JP-A-63-185802, but in the present invention, water or an aqueous catalyst solution is used. It is characterized in that alkoxides of two or more different metals are added at different times to a W/O emulsion in which the metal is solubilized. In addition to producing ultrafine zirconia particles, the method of the present invention
．． It can be applied to the production of ultrafine particles of metal oxides such as V and other non-metal oxides such as Si02, but is not limited to these, and any metal that forms metal alkoxides may be used.

The present invention will be explained in detail below using the production of zirconia ultrafine particles as an example. The metal oxide fine particles according to the present invention are mainly particles with a particle size of t,ooo or less, which have adsorbed or adhered a water-soluble or oil-soluble surfactant in a surfactant-water-nonpolar organic liquid W/O emulsion. They are ultrafine particles and are generally obtained as dispersed in a nonpolar organic solvent.

One or more types of surfactants are used. When an oil-soluble surfactant is used, it may be used alone, but alcohol, fatty acid, nonionic surfactant, alkasol, etc. may be added as appropriate. On the other hand, when a water-soluble surfactant is used, alcohol, fatty acids,
Fine particles are generated by adding a nonionic surfactant, alkanol, etc. to make it oil-soluble. For example, a W/O nimulsion based on a surfactant, water, and alkanol nonpolar organic solvent system is preferably used.

Desirable usage concentrations of surfactant and water for non-polar organic liquids are 0.01-1101/kK and 0.01-10 mol/kg, respectively.

Incidentally, a W/O type microemulsion of surfactant/water/nonpolar organic solvent is a thermodynamically stable solution with a highly dispersed water system.

Representative examples of water-soluble or oil-soluble surfactants used in the production of ultrafine metal oxide particles according to the present invention include (1) R″OSO, M (where R1 is an alkyl group of C6 to C, . (M is an alkali metal or alkaline earth metal.) (2) RL-@-OS03M (However, Ri and M are the same as in (1) above. is, )(3
) R1SO3M (However, R1 and M are the same as in (1) above.) (4
) Ri-@-803M (However, R1 and M are the same as in (1) above.) (5
) R”N”(CH3)3 ・X- (However, R2 is C
,~Cz. The alkyl group X- is a halogen ion. ) (6) n"N"H, x- (However, R2 and X1 are the same as in (5) above.) (
7) R"-C:N"-X- (However, R2 and X are the same as in (5) above.) (8
) R3COOCI+, ! I'13COOCI1, Z (However, R3 is C, ~Cs alkyl group, Z is -So,
H, -0SQ314 or 1COOH alkali metal or alkaline earth metal. ) (9) R30C}l. C}IC}1,OR” (However, R1 and Z are the same as in (8) above,) (10)
R''R'R'\ 1 / C Z (However, R1 and 2 are the same as in (8) above.) M (However, R3 and 2 are the same as in (8) above.) (However, R4 and R' are both alkyl groups with a total carbon number of 10 to 36. X1 is a halogen ion.) (13) R' \ N"l{, . S (However, R'.R' and x'' are the same tear as in (12) above.) (14) R'NI{, GOOCR' (However, R6 is C. to C1. Preferably C.z saturation, Examples include an unsaturated or side chain alkyl group, R7 is C8 to C1, preferably << is a C■ saturated, unsaturated or side chain alkyl group. Examples of alcohols, fatty acids, nonionic surfactants, and/or alkanols (alkylaryl sulfonate, an anionic surfactant manufactured by DuPont, USA) that can be added to these surfactants include the following: can give. (a) Alcohol (having an alkyl group with 1 to 20 carbon atoms, preferably 1 to 10) (alpha) Fatty acid (having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms)
having 10 alkyl groups) (c) s”-@-o-+co, cI{, o+-r
1o (However, R8 has 1 to 20 carbon atoms, preferably 1 to 1
0 alkyl group, particularly preferably an unsaturated or side chain alkyl group. n is 1-20, preferably 1-10
is an integer. ) (2) R'O+CH, CH, O +, Hn (However, R0 is the same as the above formula (c). n' is 1 to
20, preferably an integer from 4 to 10. ) (E) CHOCO − R” CHO}I CH, OH (However, R1 is an alkyl group having 8 to 20 carbon atoms, preferably an unsaturated or side chain alkyl group.) (F) R”CO + CH. CI,0 ) \ / C HOH (However, R3 is the same as the above formula (E).) (Left below is blank space) (H) HO + et H40 ya → C, } l, O cypress → C, H
Wholesale Kanko 41 (where n is an integer of 1 to 10, preferably 1 to 3, and m is an integer of 5 to 20, preferably 5 to 10.
) (Alkylaryl sulfonate) These surfactants (including alkanols), alcohols, fatty acids, etc. may be used alone, but 2
More than one species may be used in combination.

The non-polar organic liquid is primarily present as a non-aqueous dispersion medium when the dispersion is prepared. Various kinds of organic liquids (organic solvents) can be used, but representative examples include petroleum hydrocarbons such as kerosene and Isopar H (trade name, manufactured by Esso Standard Oil Co., Ltd.); hexane, octane, and cyclohexane. , cyclopentane, benzene, toluene, xylene; halogenated hydrocarbons such as carbon tetrachloride, trichloroethylene, tetrachloroethane, dichlorobenzene; ethers such as diethyl ether, isopropyl ether; ethyl acetate, propyl ether; Examples include alcohols such as ester foctyl alcohol such as viracetate and phenylacetate, nonyl alcohol, decyl alcohol, and benzol alcohol, among which the use of cyclohexane is particularly effective. These solvents may be used alone or in combination of two or more. To produce the fine particles of the present invention, a W/O type microemulsion phase consisting of a surfactant, water, and nonpolar organic liquid is used. First, zirconium alkoxide is added, and after a predetermined period of hydrolysis reaction, calcium, magnesium, and
An alkoxide of at least one metal selected from lanthanide elements such as yttrium or cerium may be further added and a hydrolysis reaction may be carried out for a predetermined period of time. The ratio of the amount of the metal alkoxide that acts as a stabilizer to the zirconium alkoxide may be determined to be the most stable ratio when sintered as a zirconia ceramic raw material powder. Usually 0.1~30++
It is preferable to set it as +oQ% (more preferably 0.1-10oQ%). Further, examples of the alkyl group of the metal alkoxide used in the present invention include methyl, ethyl, probyl, and butyl groups. It is more advantageous to carry out the above hydrolysis reaction in the presence of a catalyst. Acids such as sulfuric acid and hydrochloric acid and bases such as ammonia can be selected depending on the type of metal alkoxide, and in the case of zirconium alkoxide, acids are used. Ru. Furthermore, the production of fine particles by this hydrolysis reaction is preferably carried out under stirring conditions.

In the thus produced microgel dispersion containing ultrafine metal oxide particles of the present invention, the parent wood group side of the oil-soluble surfactant firmly adheres to or adsorbs to the ultrafine particles, and it becomes non-polar. It is dispersed in a sterile organic solvent. Since the microgel itself in the present invention is water-insoluble, it can be dispersed in both aqueous and oily systems. Therefore, in the production of the ultrafine particles of the present invention, it may be considered to replace the dispersion medium from the organic liquid to water later if necessary. Ultrafine zirconium oxide particles, in which an oxide (sintering stabilizer) of at least one metal selected from
They are spherical particles smaller than a human being (usually called ultrafine particles),
Furthermore, it has a sharp particle size distribution. This, in addition to the fact that the stabilizer is uniformly dispersed, is an important factor for obtaining a stabilized zirconia sintered body.

Next, examples will be shown.

Example 1 NP-6, C, H, 1◎→(co2c
o,O)s}l, cyclohexane was used as a nonpolar solvent, and zirconium tetra n-butoxide and yttrium tri'-n- were used as metal alkoxides.
Ultrafine particles were produced using butoxide and sulfuric acid as a catalyst.

First, we investigated the solubilization state of this sulfuric acid aqueous solution/NP-6/cyclohexane system with various addition amounts of sulfuric acid and water in order to obtain a guideline for the range of addition amounts of sulfuric acid and water suitable for the preparation of ultrafine particles. As a result, we obtained the results shown in Figure 1. In the figure, ~P- of 0.2moΩ8g
67 In a system using cyclohexane solution, NP-
The solubilization state is classified into three regions: transparent, blue-transparent, and opaque, with the horizontal axis representing the molar ratio of sulfuric acid to NP-6 (-Rs) and the vertical axis representing the molar ratio of water to NP-6 (=Rw). did.

From this result, the transparent region suitable for preparing ultrafine particles is Rs.
= [H, So4/[NP-6 is approximately 0.3 or less,
R w − [ Hz Oko/[NP-6 Ko was estimated to be approximately 15 or less. Note that this solubilized state varies greatly depending on the nonpolar organic solvent, the type and concentration of the surfactant, and the combination of the catalyst.

Figure 2 shows R w = 10 in the above transparent region.
,Rs=0.15;Rw=5,Rs=0.15;Rw
=5+Rs=0.10, 0.05m of zirconium tetra n-butoxide as the alkoxide
This figure shows the change in particle size depending on the reaction time when ultrafine zirconium oxide particles were produced in v4 using a concentration of oQ/kg. From FIG. 2, no increase in particle size is observed after about 48 hours of reaction time, and it is estimated that the reaction is almost complete. Therefore, after the reaction is complete, if a different metal alkoxide is further added and reacted, particles of zirconium oxide coated with another metal oxide can be obtained. In a 0.2 moQ/kg NP-6/cyclohexane solution, Rs-=0.1. Solubilize sulfuric acid and water so that Rw = 5, and add 0 zirconium tetra n-butoxide to it.
．． After adding 1 mol2/kg and stirring with a magnetic slurry (50 hours) to complete the hydrolysis reaction,
Furthermore, 0.01 yttrium tri-n-butoxide
It was added at a concentration of moQ/kg and reacted with stirring in the same manner. After that, when we observed the particle shape and particle size using an electron microscope, we found that the average particle size was 300, [standard deviation/average] = 0.0
Spherical ultrafine particles of No. 2 were obtained, and as a result of elemental analysis, the ratio of zirconium to yttrium contained therein was approximately 100:
It was 9.

Example 2 Calcium di-n-butoxide was used in place of yttrium tri-n-butoxide used in Example 1, and R s
= 0.15, Rw = IO was carried out in the same manner as in Example 1, and spherical ultrafine particles with an average particle diameter of 550 and [standard deviation/average] = 0.02 were obtained, and elemental analysis As a result, the ratio of zirconium to calcium contained therein was approximately 100:9.

〔effect〕

The method for producing ultrafine metal oxide particles of the present invention involves adding two or more different metal alkoxides at different times to a W/O type microemulsion in which water or an aqueous catalyst solution is solubilized, and stirring the mixture. Since it can be carried out with simple operations, the manufacturing cost of the ultrafine particles is low, and industrial mass production can be easily carried out. Furthermore, according to the method of the present invention, fine particles with a sufficiently small particle size (1000 particles or less, preferably 500 particles or less) and a sharp particle size distribution can be obtained. Since the sintering properties are greatly improved, it is possible to lower the sintering temperature and shorten the sintering time, and it is also possible to reduce the cost of producing sintered bodies. Ultrafine metal oxide compositions, especially zirconium oxide compositions, contain a metal oxide that acts as a stabilizer during sintering of zirconium oxide and is uniformly dispersed only on the surface of the zirconium oxide particles. , which is much more stable than conventional products, and using this ultrafine particulate composition makes it possible to produce higher-purity zirconium ceramics.

[Brief explanation of the drawing]

FIG. 1 is a phase diagram showing the solubilization state of the H, SO, aqueous solution/surfactant NP-6/cyclohexane system used in Example 1. FIG. 2 is a graph showing the relationship between the reaction time and the diameter of the produced particles when ultrafine zirconium oxide particles are produced from zirconium alkoxide in the transparent region of FIG. Fig. 1 Temperature Rs; (H2504]/[NP-61 Fig. 2 Time/hr -28-

Claims (1)

[Claims] 1. In a method for producing an ultrafine particulate metal oxide composition by a hydrolysis reaction of a metal alkoxide in a surfactant-water-nonpolar organic liquid W/O microemulsion, water or an aqueous catalyst solution is solubilized. A method for producing an ultrafine particulate metal oxide composition, which comprises adding two or more different metal alkoxides to a W/O type microemulsion individually at different times to carry out a hydrolysis reaction.