JPH0611647B2 - Method for synthesizing aluminosilicate powder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a homogeneous aluminosilicate powder, and provides a high-purity, low-temperature sinterable, dense and highly reliable structure. The present invention relates to a method for producing aluminosilicate powder, which is used as a raw material for electronic component substrates and the like.

[Conventional technology]

Generally, aluminosilicate ceramics are produced by mixing, molding and firing powders of oxides of each component.
In this method, since the desired aluminosilicate ceramics are formed by the solid-phase reaction due to firing, a high firing temperature is required, and it is difficult to obtain a dense structure because the composition is not uniform.

In addition, although a coprecipitation method for supplying finer powder has been proposed, it is difficult to precipitate multiple components at the same time with this method, and a deviation from the target composition is likely to occur. It becomes a mixed powder. In addition, a method for preparing a powder using a metal alkoxide as a starting material has been proposed, but similarly, it is difficult to homogenize multi-components due to the difference in hydrolysis rate, and gelation easily occurs and a good powder cannot be obtained. In many cases.

The present inventors have filed a patent application No. Heisei as a method for producing a homogeneous composite oxide precursor using a metal alkoxide or the like as a starting material.
The method of 1-45341 was found, but it was mainly related to the sol-gel method, and it was insufficient for producing powder suitable for ceramics production. A powder can also be obtained by pulverizing the obtained gel after drying or calcination, but its particle size distribution is wide and it is not suitable for dense ceramics production.

[Problems to be Solved by the Invention]

An object of the present invention is to solve the above problems and to provide a method for producing an aluminosilicate powder which is homogeneous and has a good particle size and particle size distribution with no deviation from the target composition.

[Means for Solving the Problems]

The present invention relates to a method for synthesizing an aluminosilicate powder using at least a metal alkoxide as a starting material, in which a silicon alkoxide is acidified with water in an amount equal to or more than the total amount of aluminum alkoxide and alkaline earth metal and not more than 3 times the mole of silicon alkoxide. After adding together with it, aluminum alkoxide is added and reacted, then alkaline earth metal or alkaline earth metal alkoxide is further reacted and then the solvent is removed to prepare a composite precursor,
The obtained composite precursor is diluted with a solvent again, water having a pH of 11 or more is added again to precipitate the powder, and then the powder is separated by a method for synthesizing an aluminosilicate powder,
The above objective was achieved.

The present invention will be described in detail below.

The silicon alkoxide is not particularly limited as long as the alkoxy group has 1 to 4 carbon atoms, but considering the content of metal silicon in the raw material silicon alkoxide, the ease of controlling the hydrolysis reaction, and the cost. Most preferably, it has 2 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, etc. are used.

The amount of water added to the silicon alkoxide is extremely important for obtaining a uniform and good powder shape, and water equal to or more than the total amount of aluminum alkoxide and alkaline earth metal and 3 times or less mol of the silicon alkoxide is used. . If the amount is less than the equimolar amount of aluminum alkoxide, the reaction between aluminum and silicon does not proceed sufficiently to obtain a homogeneous composite precursor, and as a result, a homogeneous powder cannot be obtained. Further, when the amount of water is equimolar or more with aluminum alkoxide, a homogeneous composite precursor is obtained, but when the total amount of aluminum alkoxide and alkaline earth metal is equimolar or less, a powder having a strong gelation tendency and a good particle size distribution is obtained. I can't get it. Further, if the amount of water used is more than 3 times the molar amount of the silicon alkoxide, precipitation will occur during the precursor synthesis and a homogeneous precursor cannot be obtained.

Hydrochloric acid is preferable as the acidic catalyst because it is easily removed later, but an organic acid such as hydrofluoric acid, sulfuric acid, or acetic acid can also be used.

The silicon alkoxide, water and the acidic catalyst are reacted in a solvent, and alcohol or a solvent containing alcohol is used as the solvent, and methanol and ethanol are preferable. However, when an alkaline earth metal is added as an alkoxide, it is not particularly necessary to contain an alcohol, and a general solvent such as toluene, xylene or hexane can be used.

Aluminum alkoxide is added and reacted, but as the aluminum alkoxide, the number of carbon atoms of the alkoxy group is 1-
4 may be used. At the time of this reaction, it is preferable to reflux the solution because the reaction proceeds rapidly.

After that, an alkaline earth metal is added and further reacted, and magnesium, calcium, strontium and barium are used as the alkaline earth metal. The alkaline earth metal is added as a metal piece or an alkoxide. Also in this reaction, it is preferable to reflux the solution because the reaction proceeds rapidly.

An alkaline earth metal is added and further reacted to form a transparent homogeneous solution, and the solvent is removed under reduced pressure to prepare a composite precursor.

The prescribed solvent is added again to dilute.

Here, the predetermined solvent is not particularly limited as long as it dissolves the composite precursor, but alcohols or ketones are preferable. However, a large difference is found in the particle size, particle size distribution and particle porosity of the powder obtained depending on the type of solvent used, and ketones and methanol are most preferred.

Water is added again to the diluted composite precursor to precipitate the powder, but the water added again is limited to pH pH 11 or above. If the pH is less than 11, the stoichiometry of the powder produced will not be satisfied, and specifically the silicic acid content will be low.

The dilution ratio with the solvent and the amount of water to be added again at pH 11 or more are important and particularly good ranges for obtaining a good powder. Is more than 3 times the amount of hydrolyzing the alkoxy group. If the dilution ratio is less than 3 times by volume, the gelation tends to be strong and a good powder cannot be obtained. If it exceeds 15 times by volume, it will be in a sol state and will not likewise become a powder. Generally, the higher the dilution rate, the finer the particles. If the amount of water is less than 3 times the amount that hydrolyzes the alkoxy groups, gelation occurs and good powder cannot be obtained.

It has been found that when a nonionic dispersant is added during re-dilution with a solvent, a fine powder is obtained even if the dilution ratio is low, and the particles obtained without the addition of the dispersant are more dense.

The obtained powder is separated by filtration or centrifugation and dried and then calcined. However, in this system containing silicic acid, the problem of residual organic matter is likely to occur. Boiling with water containing hydrogen peroxide is extremely effective in removing residual organic substances.

The aluminosilicate powder obtained by the present invention has a high purity, a fine particle size, can be sintered at a low temperature, and has excellent electric characteristics to produce a substrate for mounting an electronic material or electronic component or a multilayer ceramic substrate. can do.

[Action]

In the present invention, it is considered that the aluminosilicate ester alkoxide is synthesized by the reaction of silicon alkoxide and aluminum alkoxide. Further, in the case of metal pieces, further reaction with an alkaline earth metal will react with alcohol in an organic solvent to form an alkoxide, which will form a complex with the aluminum alkoxide end of the aluminosilicate alkoxide to form a composite precursor. .

The amount of water used is directly related to these compositing, and it seems that the proper compositing is important for obtaining a good powder. When the amount of water used is small, it becomes a precursor with insufficient complexation, polycondensation in powder preparation does not proceed sufficiently,
As a result, the gelation tendency is strong, and it seems that good powder cannot be obtained and homogeneous particles are not obtained.

It is considered that by adding water having a pH of 11 or more, polycondensation proceeds satisfactorily, and unreacted substances do not remain in the solution to obtain a powder having a stoichiometric composition.

Moreover, after the composite precursor is concentrated, it is diluted with ketones such as acetone or methanol, but in the case of ketones, it is considered that a good powder can be obtained because the hydrolysis product has an appropriately low solubility. Further, in the case of methanol, it is considered that the OR group of the composite precursor is transalkylated to promote hydrolysis and polycondensation, whereby a good powder can be obtained.

Further, when a nonionic dispersant is added, fine and dense particles can be obtained even at a low dilution rate, which is considered to be because the particle collision during particle formation was prevented and the growth on the particle surface was promoted.

Further, it is considered that the separated powder is boiled with water containing hydrogen peroxide water to remove the organic components remaining in the pores in the particles, so that the residual carbon after firing is eliminated.

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

Example 1 Tetraethoxysilane (52.1 g) was dissolved in ethanol (125 ml), 1N.HCl (2.5 ml) and water (2.9 ml) were added under ice cooling for partial hydrolysis, and tri-sec-butoxide aluminum (49.3) suspended in 100 ml of ethanol was suspended. g and refluxed, 2.4 g of metal magnesium was further refluxed, and the resulting solution was concentrated under reduced pressure to remove the solvent and obtain a composite precursor. To this composite precursor, 230 g of acetone was added, and 1.8 g of a sorbitan monooleate-based dispersant was added. Add 300 g of acetone to this solution.
And a mixed solution of 522 g of 1N ammonia water (pH 11.7) was added to form particles, and the particles were left for 24 hours. The obtained precipitated particles are washed with acetone, and about 200 g of water added with hydrogen peroxide is added, refluxed, filtered again, washed with water, and dried to obtain a particle size of about 0.
2 μm powder was obtained.

Example 2 Tetraethoxysilane (41.7 g) was dissolved in ethanol (100 ml), 1N.HCl (2.5 ml) and water (4.7 ml) were added under ice cooling to partially hydrolyze, and then suspended in ethanol (100 ml) tri-sec-.
Aluminum butoxide 49.3 g was added and refluxed, and further metallic calcium 4.0 g was added and further refluxed, and the obtained solution was concentrated under reduced pressure to remove the solvent to obtain a composite precursor. 500 g of methanol was added to this composite precursor. A mixed solution of 750 g of methanol and 522 g of 1N ammonia water was added to this solution to form particles, and the particles were left for 24 hours. The precipitated particles obtained were washed with acetone, and water containing hydrogen peroxide was added to
Add 200 g, reflux, filter again, wash with water and dry to a particle size of 0.4
A μm powder was obtained.

Comparative Example 1 Tetraethoxysilane (52.1 g) was dissolved in ethanol (125 ml), 1N.HCl (2.5 ml) and water (1.1 ml) were added under ice cooling to partially hydrolyze, and then suspended in 100 ml of ethanol Tri-sec-.
49.3 g of butoxide aluminum was added and refluxed, and further 2.4 g of metal magnesium was added and further refluxed. The obtained solution was diluted with 500 g of ethanol. When a mixed solution of 750 g of ethanol and 522 g of 1N ammonia water was added to this solution, particles did not precipitate, and gelled when left for 48 hours.

Example 3 and Comparative Example 2 A composite precursor was prepared in the same manner as in Example 1. 500 g of acetone was added to this composite precursor. To this solution, 750 g of acetone and HCl water having a pH of 1,3,5 or a mixed solution of pH 7.9 (the above comparative example) and (the following examples) 522 g of 11.2, 11.7, and 13.5 ammonia water were added to form particles. Let it stand for 24 hours.

The obtained precipitated particles were washed with acetone, and about 200 g of water containing hydrogen peroxide was added, refluxed, filtered again, washed with water and dried to obtain a powder. When ICP composition analysis was performed on these powders, a deviation from the stoichiometric composition was confirmed as shown in Table 1.

Comparative Example 3 A composite precursor was prepared in the same manner as in Example 1. N-hexane, cyclohexane, toluene, ethanol, propanol and butanol were added to this composite precursor, respectively.
0 g was added. To this solution, add 52 mL of ammonia water having a pH of 11.5.
2 g was added and left for 48 hours. The obtained products are shown in Table-2. No good powder was obtained with all solvents.
The solvent of the present invention used in Examples 1 and 2 is also shown.

[Effects of the Invention] According to the present invention, it is possible to obtain aluminosilicate powder having high purity, homogeneity, and good powder shape, and these powders can be sintered at a low temperature, and the obtained sintering The body has a fine and dense structure and excellent surface smoothness, and shows good electrical characteristics, and is suitable for electronic materials.

Claims (5)

[Claims] 1. A method for synthesizing an aluminosilicate powder using at least a metal alkoxide as a starting material, wherein at least equimolar amount of aluminum alkoxide and alkaline earth metal and not more than 3 times mol of silicon alkoxide are acidified to silicon alkoxide. After adding together with the catalyst, aluminum alkoxide is added and reacted, and then alkaline earth metal or alkaline earth metal alkoxide is further reacted, and then the solvent is removed to synthesize a composite precursor,
A method for synthesizing an aluminosilicate powder, which comprises diluting the obtained composite precursor again with a solvent, adding water having a pH of 11 or more again to precipitate the powder, and then separating the powder. 2. The dilution ratio of the composite precursor in a solvent is 3-15.
The synthesis of the aluminosilicate powder according to claim 1, wherein the amount of water having a pH of 11 or more to be added again is 3 times or more the molar amount of hydrolyzing all the alkoxy groups of the composite precursor. Method. 3. The method for synthesizing an aluminosilicate powder according to claim 1, wherein the diluting solvent is a ketone or methanol. 4. A nonionic dispersant is added when the solvent is diluted again with a solvent.
A method for synthesizing the aluminosilicate powder according to the item 1. 5. The method for synthesizing an aluminosilicate powder according to claim 1, wherein the separated powder is boiled in water containing hydrogen peroxide solution.