JPH02175602A - Production of ultrafine particle metal oxide composition and ultrafine particle zirconium oxide composition obtained thereby - Google Patents

Abstract

PURPOSE:To obtain a composition having high density and large strength and especially suitable as zirconia ceramic raw material by solubilizing an aqueous solution of salt of a metal different from a metal of a metal alkoxide in W/O type microemulsion and then adding the metal alkoxide to the solution and hydrolyzing the metal oxide. CONSTITUTION:When ultrafine-particle metal oxide composition is produced by hydrolysis reaction of a metal alkoxide in surfactant-water-nonpolar organic liquid based W/O type, the reaction is carried out as follows: An aqueous solution of salt of one or more kinds of metal different from a metal contained in a metal alkoxide are solubilized in W/O type microemulsion and the metal alkoxide is added thereto and hydrolyzed to provide the aimed composition. The ultrafine-particle zirconium oxide composition obtained by the above- mentioned method is a composition containing oxide of at least one metal selected from Ca, Mg, Y and lanthanoid based element in particle unit and uniformly dispersed state and having <=1000Angstrom particle diameter.

Description

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

[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 filtration and water washing, or a method of heating and hydrolyzing an aqueous solution of a water-soluble zirconium salt to generate a sol, followed by drying and calcining, 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 the addition of a stabilizing agent to zirconia can be achieved by adding a salt of the above metal to an aqueous solution of a water-soluble zirconium salt, or This is accomplished by adding salts or oxides of the metals mentioned above during the calcination stage. (JP-A-Sho) The zirconia fine powder thus obtained can be used as zirconia ceramics by sintering it, but after obtaining a hydroxide or oxide sol by the above conventional method, The powder obtained by drying has agglomerated particles that are difficult to loosen and cannot be easily made into fine powder.
If this is used as a ceramic raw material as it is, the moldability and sinterability are greatly affected, and a sufficiently satisfactory sintered body cannot be produced.

In order to obtain a stabilized zirconia sintered body, it is necessary to uniformly disperse the stabilizer into a solid solution, but conventionally known methods are not fully satisfactory in this respect.

Conventionally, a method has been developed to reduce the amount of hydroxide in the hydrolyzed product as much as possible in order to satisfy the requirements for zirconium oxide as a raw material for ceramics (Japanese Patent Application Laid-Open No. 79818/1983).
, a method using an organic solvent to prevent agglomeration during drying (Japanese Patent Publication No. 54-25523), zirconium salt alone, or zirconium salt and at least one selected from magnesium, calcium, and a metal element having a valence of 3 or more. As a method of drying an aqueous solution consisting of one type of salt, a method using a spray dryer (Japanese Patent Application Laid-Open No. 60-86025) has been proposed, but this method is not necessarily satisfactory.

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, in order to improve sinterability, a powder having a small particle size and a sharp particle size distribution is required.

〔the purpose〕

An object of the present invention is to provide a raw material for zirconium oxide fine particles that satisfies the above conditions and a method for producing the same, which enables the production of high-density, high-strength, and excellent zirconia ceramics.

〔composition〕

As a result of intensive research to achieve the above object, the present inventor has developed an ultrafine metal oxide composition produced by a hydrolysis reaction of a metal alkoxide in a surfactant-water-nonpolar organic liquid system W10 microemulsion. In the production method, an aqueous solution of a salt of one or more metals different from the metal contained in the metal alkoxide is solubilized in a W10 type microemulsion, and then a metal alkoxide is added,
It has been found that the above object can be achieved by providing a method for producing an ultrafine particulate metal oxide composition characterized by carrying out a hydrolysis reaction.

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 a particle size that contains an oxide of at least one metal selected from calcium, magnesium, yttrium, and lanthanide elements uniformly dispersed in particle units. is 1,000 Å or less, preferably 3
This is an ultrafine zirconium oxide composition with a particle size of 00 Å or less.

As a method for producing metal oxide fine particles by the hydrolysis reaction of metal alkoxide in a W/O type dichroic emulsion, there is a method disclosed in JP-A-63-185802. An aqueous solution of a salt of one or more metals different from the metal
It is characterized in that the metal alkoxide is added after being solubilized in the /O/O emulsion.

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, but
The metal is not limited to these, and any metal that forms a metal alkoxide may be used. The present invention will be described in detail below by taking the production of ultrafine zirconia particles as an example.

The metal oxide fine particles according to the present invention are ultrafine particles mainly having a particle size of t, oooÅ or less and adsorbing or adhering to a water-soluble or oil-soluble surfactant in a W10 type emulsion based on a surfactant-nonpolar organic liquid. It is generally obtained as a dispersed state in a nonpolar organic solvent.

Five or more types of surfactants are used.

When an oil-soluble surfactant is used, the oil-soluble surfactant may be used alone, but alcohol, fatty acid, nonionic surfactant, alkanol, etc. may be added as appropriate.

On the other hand, when a water-soluble surfactant is used, it is necessary to make it oil-soluble, so alcohol, fatty acids, nonionic surfactants, alkanols, etc. are added to make it oil-soluble and generate fine particles. It will be done. For example, surfactant - water -
Alcatul non-polar organic solvent based W10 emulsion is successfully used.

The generally desirable working concentrations of surfactant and water for non-polar organic liquids are 0.01~Jmo],/kg, respectively.
and O2 ~], Omol/kg.

Incidentally, the W10 type microemulsion of surfactant/water/nonpolar organic solvent is a thermodynamically stable solution with a highly dispersed water system.

Typical examples of water-soluble or oil-soluble surfactants used in the production of ultrafine metal oxide particles according to the present invention include (1) R10S03M (wherein R1 is a C6 to C□2 alkyl group, preferably an unsaturated surfactant); It is a saturated alkyl group or a side chain alkyl group. M is an alkali metal or alkaline earth metal.) (2) R1-o-O303M (However, R1 and M are the same as the above (],).) (
3) R'SO3M (However, R' and M are the same as in (1) above.) (4
) R'÷SO3M (However, R1 and M are the same as in (1) above.) (5
) R”N+(CI(3)3-X (However, R2 is C8
~C2o alkyl group, X- is a halogen ion.

) (6) R2N+H3・X- (However, R2 and X- are the same as in (5) above.) R
3R3R3 \ 1 / (However, R3 and Z are the same as in (8) above.) (However, R2 and X are the same as in (5) above.) (8)
R'C00CR□ R''C00CH7 (However, R3 is an alkyl group of 04 to CB, 2 is 5o3H
It is an alkali metal or alkaline earth metal of 1-0SO3H or 1000H. ) (9) R30CH2CHCH2OR3 (However, R3
and 2 are the same as (8) above. ) (However, R3 and 2 are the same as in (8) above.) (However, R4 and R5
are both alkyl groups, and the total number of carbon atoms in both alkyl groups is 10 to
36. X- is a halogen ion. )(
13) R4 \ N+11□・X / (However, R4, Rs and or a side chain alkyl group, R7 is a C1 to C18, preferably C2, saturated, unsaturated or side chain alkyl group.

) etc.

Examples of alcohols, fatty acids, nonionic surfactants, and/or alkanols (alkylaryl sulfonate, an anionic surfactant manufactured by DuPont, USA) that are added to these surfactants include the following: can give.

(a) Alcohol (having 1 to 20 carbon atoms, preferably 1 to 20 carbon atoms)
(b) Fatty acid (having 1 to 20 carbon atoms, preferably 1 to 20 carbon atoms)
having 10 alkyl groups) (c) R″-@-0-(-cH2CH20+nH
(However, R8 is an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and is particularly preferably an unsaturated or side chain alkyl group. n is an integer of 1 to 20, preferably 1 to 10. ) (d) R80-fcH2CH20tHn' (However, R8 is the same as in the above formula (c).

n' is an integer from 1 to 20, preferably from 4 to 10. ) (E) CHOCO-R' HOH H20H (However, R9 is an alkyl group having 8 to 20 carbon atoms, preferably an unsaturated or side chain alkyl group.) (F) R10CO-+ CH2CH2O+OH (However, R " is an alkyl group having 4 to 20 carbon atoms, preferably 8 to 18 carbon atoms, and is particularly preferably an unsaturated or side chain alkyl group. n is the same as in the formula (c) above.) \ / OH (However, , R9 is the same as the above formula (E).) (H)
no-(C2H40se C3H, O+-fC, H, No. 0 H (however, Q is an integer of 1 to 10, preferably 1 to 3, m
is an integer from 5 to 20, preferably from 5 to 1O. ) (S) Alkylaryl sulfonate These surfactants (including alkanols), alcohols, fatty acids, etc. may be used alone, but 2
It is okay to use more than one species 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 typical examples include petroleum hydrocarbons such as kerosene and Isopar H (trade name, manufactured by Ethane Standard Oil Co., Ltd.); hexane, octane, and cyclohexane. , cyclopentane, benzene,
Non-polar hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as carbon tetrachloride, trichloroethylene, tetrachloroethane and dichlorobenzene; ethers such as diethyl ether and isopropyl ether; esters such as ethyl acetate, propyl acetate and phenyl acetate; octyl Examples include alcohols such as alcohol, nonyl alcohol, decyl alcohol, and benzyl alcohol, among which cyclohexane is particularly effective. These solvents may be used alone or in combination of two or more. In order to produce the fine particles of the present invention, a surfactant-ho nonpolar organic liquid system W
Solubilized in the Type 10 microemulsion phase is an aqueous solution of at least one metal salt selected from lanthanide elements such as calcium, magnesium, yttrium, or cerium, which acts as a stabilizer when sintering zirconia ceramic raw materials. After this, zirconium alkoxide may be added to cause hydrolysis. The ratio of the metal salt to the zirconium alkoxide may be determined to be the most stable ratio when sintered as a zirconia ceramic raw material powder. Usually 1.0-3
It is preferable to set it as 0moQ% (more preferably 0.1-10moQ%). Further, examples of the alkyl group of the metal alkoxide used in the present invention include methyl, ethyl, propyl, and butyl groups. It is more advantageous to carry out the two-layer hydrolysis reaction in the presence of a catalyst, and sulfuric acid, hydrochloric acid, etc. can be used as the catalyst. Further, examples of the metal salts include sulfates, halides, nitrates, acetates, etc., but since the solubility of the salt in water varies depending on the type of metal, those having a certain degree of solubility are preferred. Furthermore, the production of fine particles by this hydrolysis reaction is preferably carried out under stirring conditions.

In the thus produced microgel dispersion containing the metal oxide ultrafine particles of the present invention, the hydrophilic group side of the oil-soluble surfactant is firmly attached or adsorbed to the ultrafine particles, and the nonpolar It is in a state of being dispersed in an 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 later replace the dispersion medium from the organic liquid with water, if necessary.

The ultrafine zirconium oxide particles obtained by the present invention have an oxide (sintering stabilizer) of at least one metal selected from lanthanide elements such as calcium, magnesium, yttrium, or cerium uniformly dispersed in each particle. , the particle size is approximately 1. ．． They are spherical particles of 000 Å or less (usually called ultrafine particles) and have 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 Surfactant L TeNP-6C,H,, -G-0(CH
□CH20), H was used, cyclohexane was used as a nonpolar solvent, and yttrium sulfate and zirconium tetra- were used as metal salts and metal alkoxides, respectively.
Ultrafine particles were produced using n-butoxide and sulfuric acid as a catalyst. First, 0.2 moQ/k
g of NP-6/cyclohexane solution. After a certain period of time had passed and solubilization equilibrium was reached, zirconium tetra n-butoxide was added and stirred with a magnetic stirrer to complete the hydrolysis reaction (25
℃). After stirring for a specified time, sample on a mesh,
The shape and size of the particles were observed using an electron microscope.

The solubilization state of the 11□SO4 aqueous solution/NP-6/cyclohexane system was as shown in FIG. Clean ultrafine particles with spherical shape and no agglomeration were obtained with R8: [:H, SO,]
/l:NP-6) molar concentration ratio was 0.3 or less, and the Rw:[HzO)/[:NP-6] molar concentration ratio was 15 or less.

Rs=0.1, Rw=5, alkoxide concentration 0. ]
When stirred for 120 hours at mofl/kg, spherical ultrafine zirconium oxide particles with an average particle size of 280A were obtained, and elemental analysis revealed that the ultrafine zirconium oxide particles contained about 1 mo12% of yttrium oxide.

Example 2 The same procedure as in Example 1 was conducted except that calcium chloride was used in place of yttrium sulfate used in Example 1, and Rs = 0.15 and Rw = 10. Zirconium oxide spherical particles were obtained, and elemental analysis showed that they contained about 1% calcium oxide.

Example 3 Same as Example except that Rs = 0.15 and Rw = 5],
When conducted in the same manner as in Example 1, zirconium oxide spherical particles with an average particle size of 350 were obtained, and the results of elemental analysis were also as in Example 1.
It was the same.

[Effect] The method for producing ultrafine metal oxide particles of the present invention involves a simple process of preparing a W10 type microemulsion in which an aqueous solution containing a metal salt is solubilized, adding a metal alkoxide to this, and stirring. Therefore, the manufacturing method is simple, the manufacturing cost is low, and industrial mass production can be easily performed. Furthermore, according to the method of the present invention, the particle size is sufficiently small (100
(0 Å or less, preferably 500 Å or less), fine particles with a sharp particle size distribution can be obtained, and therefore, when sintering these, the sinterability is greatly improved, so it is possible to lower the sintering temperature and shorten the sintering time. This makes it possible to reduce the cost of manufacturing the sintered body.

Specifically, the ultrafine zirconium oxide particles obtained by the method of the present invention are fine particles in which the metal oxide, which is a sintering stabilizer, is uniformly dispersed in each particle, so they are much more stable than conventional ones. It becomes possible to produce zirconium-based 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.

Claims (1)

[Scope of 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 system W/O microemulsion, the metal alkoxide is After solubilizing an aqueous solution of a salt of one or more metals different from the metals contained in the W/O microemulsion, adding a metal alkoxide,
A method for producing an ultrafine particulate metal oxide composition, characterized by carrying out a hydrolysis reaction. 2. An ultrafine particulate zirconium oxide composition containing an oxide of at least one metal selected from calcium, magnesium, yttrium, and lanthanide elements, uniformly dispersed in particle units.