JPH0637288B2 - Method for producing complex oxide precursor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a homogeneous complex oxide precursor,
In particular, for example, it relates to a method for producing a composite oxide precursor which is a raw material of a composite oxide ceramic used as an electronic material or an electronic component substrate.

The composite oxide is generally manufactured by mixing powders of respective component oxides or precursors thereof, molding and firing.
In this method, each raw material component that is physically and homogeneously mixed is fired to cause a solid phase reaction to form a target composite oxide.

However, in this method, the progress of solid-phase reaction is slow, and it is difficult to make the composition uniform, and in order to improve it, it is necessary to reduce the fineness of each raw material component or raise the firing temperature, resulting in inefficiency. Target. Further, when the calcinable temperature is narrow, it is necessary to add an auxiliary agent, and it is difficult to obtain a high-purity composite oxide. Therefore, a wet coprecipitation method has been proposed in order to more uniformly disperse the components and use a finer raw material as a starting material.

In addition, by dissolving two or more kinds of metal alkoxides in an organic solvent and then hydrolyzing them, a homogeneous composite oxide precursor having a small compositional deviation is obtained, and by firing it, it is homogeneous at a relatively low temperature. It is known that various complex oxides can be obtained.

[Problems to be Solved by the Invention]

However, it is difficult to sufficiently miniaturize the powder by the method of mixing and firing the powders of the respective components, and it is difficult to completely fuse the respective components during the solid phase reaction, The ceramics obtained are not homogeneous.

In the wet coprecipitation method, it is difficult to set conditions for coprecipitating multiple components at the same time, and as a result, the composition of the composite oxide precursor deviates from the intended composition, and the characteristics of the final product ceramics deteriorate.

In the method using a metal alkoxide, when the difference in the hydrolysis rate of each alkoxide to be complexed is large, it is possible to obtain a homogeneous complex oxide precursor because each hydrolysis product precipitates and gels separately. If the solubility of the alkoxide is low, it is necessary to use a large amount of solvent, and it is difficult to obtain a high-concentration metal alkoxide solution, and it is difficult to obtain a good quality composite oxide precursor. Therefore, various organic substances are added in order to make the hydrolysis rate of each alkoxide uniform or to improve the solubility of the alkoxide. However, since the organic substance used for that purpose acts to stabilize and improve the solubility by coordination of the alkoxide or formation of a chelate compound, a strong bond of the organic substance remains in the complex oxide precursor produced by hydrolysis. However, this makes it difficult to remove residual carbon during firing.

An object of the present invention is to provide a method for producing a precursor of a composite oxide that solves the above drawbacks.

[Means for Solving the Problems]

The present invention partially hydrolyzes a silicon alkoxide and adds it to a solution or dispersion of an aluminum alkoxide consisting of an alcohol or dissolved or dispersed in an organic solvent containing an alcohol to cause a reaction,
Next, after mixing and reacting metal pieces of alkaline earth metal to form a uniform solution, water is further added to carry out hydrolysis and polymerization reaction to obtain a uniform sol, gel or powdery complex oxide precursor. The above object was achieved by the method for producing a composite oxide precursor.

The present invention will be described in detail below.

The silicon alkoxide is not particularly limited as long as it has 1 to 4 carbon atoms, but the carbon number is 2 in view of the content of metal silicon in the raw material silicon alkoxide and the ease of controlling the hydrolysis reaction. Is most preferred. Specifically, tetramethoxysilane, tetraethoxysilane, etc. are used. Water is added to the silicon alkoxide to cause partial hydrolysis. The amount of water used during this partial hydrolysis is preferably 2 times or less the amount of silicon alkoxide.
Sometimes when Al / Si ≦ 1, equimolar to Si, Al / Si>
In the case of 1, the amount is preferably equal to or more than 2 mol and equal to or less than Al.

The aluminum alkoxide may be one having 1 to 4 carbon atoms. The amount of aluminum alkoxide used is determined by the composition of the target oxide.
Since / Si> 3 is difficult to form a composite of Al and Si, it is preferably 3 or less.

As the organic solvent, alcohol or a solvent containing alcohol is used, but it is not limited to the one in which the aluminum alkoxide is soluble, and any solvent in which the reaction product is soluble may be used. As the alcohol, methanol or ethanol is preferable, and particularly preferable for carrying out the reaction with an alkaline earth metal. The organic solvent used in combination with the alcohol is preferably one in which the aluminum alkoxide is soluble and does not react with the alkaline earth metal, such as toluene, xylene and hexane.

The partially hydrolyzed silicon alkoxide is added to a solution or dispersion of an aluminum alkoxide, which is made of alcohol or is dissolved or dispersed in an organic solvent containing alcohol, and is reacted.
The reaction temperature is the reflux temperature of the organic solvent. The reaction time is
It varies depending on the Al / Si ratio and is until a transparent reaction solution is obtained.

A metal piece of alkaline earth metal, for example, a shaving, is added to the reaction product and mixed, and the mixture is reacted at a reflux temperature. The alkaline earth metal to be used and its addition amount are determined according to the composition of the target composite oxide. The reaction is continued until the alkaline earth metal reacts with the alcohol in the organic solvent to form an alkoxide, which forms a complex with the aluminum present in the solution and is taken up by the solvent and stabilized.

The liquid after the reaction becomes a homogeneous solution.

Water is added to this homogeneous solution to hydrolyze, and a polymerization reaction is carried out. A viscous sol, gel or fine powder can be obtained by varying the amount of water used for hydrolysis and the amount of organic solvent in the homogeneous solution. A gel is obtained when a large amount of water is used, and a fine powder is formed when the amount of the organic solvent is large.
A viscous sol is formed by reducing the amount of water added and further removing the organic solvent after the reaction.

The composite oxide precursor obtained by the present invention is an aluminosilicate-based composite oxide precursor containing an alkaline earth metal, which is used as an electronic material or an electronic component substrate by coating, sheeting, and then firing. The composite oxide ceramic used can be manufactured.

[Work]

In the present invention, when the partially hydrolyzed silicon alkoxide is added to the solution or dispersion of the aluminum alkoxide and reacted, the aluminum alkoxide reacts with the silanol obtained by the partial hydrolysis,
It is believed that aluminosilicate ester is produced and stabilized.

When the reaction product is mixed with a metal piece of alkaline earth metal, the alkaline earth metal reacts with the alcohol in the organic solvent to form an alkoxide, which forms a complex with the aluminum alkoxide end present in the solution. Then, it is taken into the solvent and stabilized. Especially when magnesium is used, the reaction proceeds without using I ₂ or HgCl ₂ as a catalyst.

If an alkaline earth metal is used in the form of an alkoxide instead of a metal, a large amount of alcohol is used, or in the case of a magnesium alkoxide, an organic solvent such as propylene glycol or 2-ethoxyethanol is not added. To obtain a good solution. Further, the alkaline earth metal alkoxide is unstable, and it is difficult to obtain a complex oxide precursor having a predetermined composition.

From the above, it became possible to synthesize a homogeneous and highly concentrated composite oxide precursor.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples. However,
The invention is not limited to these examples.

Example 1 52.9 g of tetraethoxysilane was added to 125 m of ethanol.
After dissolving in 1 l, 2.5 ml of 1N HCl and 1.1 m of water
1 was added and hydrolyzed at room temperature to cause partial hydrolysis, and then tri-s suspended in 100 ml of ethanol was added.
49.3 g of ec-butoxyaluminum was added and the mixture was refluxed. 2.4 g of metallic magnesium was added to the above reaction solution, and further refluxed. Water 22.
5 ml was added and hydrolyzed to obtain a transparent sol, which was allowed to stand at 60 ° C. to obtain a transparent gel. This was dried and then baked at 1000 ° C. for 5 hours to obtain a white cordierite porcelain. It was confirmed by X-ray diffraction that it was a single phase of α-cordierite.

Example 2 52.9 g of tetraethoxysilane was added to 125 m of ethanol.
After dissolving in 1 l, 2.5 ml of 1N HCl and 1.1 m of water
1 was added and hydrolyzed at room temperature to cause partial hydrolysis, and then tri-s suspended in 100 ml of ethanol was added.
49.3 g of ec-butoxyaluminum was added and the mixture was refluxed. 2.4 g of metallic magnesium was added to the above reaction solution and further refluxed. The obtained transparent solution was diluted with ethanol of water 1, 90 ml of water was added, and the mixture was allowed to stand at room temperature to obtain fine particles having an average particle diameter of 0.2μ. 500
Relative density of 9 after being made into pellets with a diameter of 10 mm and a thickness of 1 mm at kgf / cm ² and baking at 1000 ° C. for 5 hours.
8% white cordierite porcelain was obtained. It was confirmed by X-ray diffraction that it was a single phase of α-cordierite.
In addition, no residual carbon was found inside.

Comparative Example 1 52.9 g of tetraethoxysilane was added to 125 m of ethanol.
After dissolving in 1 l, 2.5 ml of 1N HCl and 1.1 m of water
l was added and hydrolyzed at room temperature, and then ethanol 100 was added.
tri-sec-butoxyaluminum 4 suspended in ml
9.3 g was added and reflux was performed. Magnesium-di-no
14.3 g of 1-propoxide and 50 ml of ethanol were added to the above solution and further refluxed, but a transparent solution could not be obtained.

Comparative Example 2 52.9 g of tetraethoxysilane was added to 125 m of ethanol.
After dissolving in 1 l, 2.5 ml of 1N HCl and 1.1 m of water
l was added and hydrolyzed at room temperature, and then ethanol 100 was added.
tri-sec-butoxyaluminum 4 suspended in ml
The mixture was added to 9.3 g and refluxed. Magnesium-di-no
1-Propoxide 14.3 g was added to propylene glycol 5
It was dissolved in 0 ml, the above solution was added thereto, and the mixture was further refluxed. The obtained transparent solution was diluted with ethanol of water 1, 90 ml of water was added, and the mixture was allowed to stand at room temperature to obtain fine particles having an average particle size of 0.6μ. After making pellets with a diameter of 10 mm and a thickness of 1 mm at 500 kgf / cm ² , firing was performed at 1000 ° C. for 5 hours, but residual carbon was found inside the pellets.

〔The invention's effect〕

According to the present invention, a homogeneous composite oxide precursor having a high metal concentration can be obtained. The complex oxide precursor obtained by the present invention is an organic substance for obtaining a uniform multi-component complex oxide precursor by firing after gelling or powdering as necessary. It is possible to obtain a high-purity composite oxide having a uniform structure, which has less residual carbon than that produced by the method of adding, and has a uniform composition at a lower temperature than before.

Claims (2)

[Claims] 1. A method of partially hydrolyzing a silicon alkoxide,
It is added to a solution or dispersion of an aluminum alkoxide, which is made of alcohol or is dissolved or dispersed in an organic solvent containing alcohol, and reacted, and then a metal piece of an alkaline earth metal is mixed and reacted.
A method for producing a composite oxide precursor, which comprises forming a uniform solution and then further adding water to carry out hydrolysis and polymerization reaction to obtain a uniform sol, gel or powdery composite oxide precursor. 2. The Al / Si ratio of silicon alkoxide to aluminum alkoxide is 3 or less, the alcohol is methanol or ethanol, and the alkaline earth metal is magnesium.
A method for producing the composite oxide precursor described.