JPS62278106A - Hydrolysis of metal alkoxide - Google Patents

Abstract

PURPOSE:To obtain a uniform and stable sol having retarded rate of hydrolysis, by adding a specific hydrolysis retarder to a reaction system containing a metal alkoxide and carrying out hydrolysis of the alkoxide. CONSTITUTION:A reaction system containing a metal alkoxide of formula (M is metallic atom; R and R' are alkyl, aryl, alkenyl or H; x is 0-3; y is 1-4; x+y is 3 or 4) and water is added with <=1wt% aromatic amine (e.g. pyridine) as a hydrolysis retarder and the alkoxide is hydrolyzed.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for hydrolyzing metal alkoxide, and in particular to a method for easily controlling the hydrolysis reaction of metal alkoxide. TECHNICAL FIELD The present invention relates to a method of retarding the rate of hydrolysis.

[Prior Art] Metal alkoxides are used in a variety of applications depending on the type of metal, such as silicon, aluminum, titanium, zirconium, etc. For example, alkoxysilanes are used in heat-resistant paints, plastic surface protection coatings, and zinc dust prevention. Rust paints, high-purity glass produced by sol-gel method, binders for precision casting and refractories, cross-linking agents with hydroxyl groups in silicone resins and organic substances, high-purity colloidal silica, other functional inorganic gels, inorganic-organic composites It is attracting industrial attention as a new inorganic material, such as body gels and hybrid gel bodies.

When producing such inorganic materials, metal alkoxides are generally hydrolyzed with a stoichiometric excess of water to produce a metal hydroxide sol, or roughly gelled. Some efforts have been made to produce metal oxide gels.

For example, when the metal alkoxide is an alkoxysilane, industrially, the following reaction formula (2) or (3) R"5iCA3+3RO)-1 →R"S i (OR)3 is usually used in the presence of a dehydrochlorination agent. +3 11 (J)
(2) Alkyltrialkoxysilane or tetraalkoxysilane is produced by S i Cf24 +4ROH →5i(OR) +4HCffl (3) (in the formula, R and R' represent an alkyl group), and the stoichiometric excess water, hydrolysis catalysts such as mineral acids such as hydrochloric acid, sulfuric acid, nitric acid, 1a acids such as acetic acid, ammonium hydroxide, quaternary ammonium hydroxide, alkali or alkaline earth oxides or hydroxides, etc. A base is added thereto and hydrolyzed with stirring to produce a silica sol, which is then gelled if necessary.

[Problems to be solved by the invention] However, the hydrolysis rate of metal alkoxides varies greatly depending on the type of metal, and it is difficult to control the reaction of metal alkoxides whose hydrolysis rate is too fast, making them difficult to use as raw materials. There have been problems in that it is difficult to store or to produce a uniform and stable sol through hydrolysis, which deteriorates the quality of the produced inorganic material.

In addition, when the metal alkoxide is an alkoxysilane, the rate of hydrolysis differs depending on the alkyl group of the alkyltrialkoxysilane or tetraalkoxysilane produced. It is unavoidable that chlorine atoms and dehydrochlorination agents remain in the hydrogen chloride produced as a by-product, and their content varies with each manufacturing lot.
This seems to be the cause, but there is a large difference in the rate of hydrolysis of alkyltrialkoxysilanes and tetraalkoxysilanes for each manufactured lot, and it is not possible to produce a uniform and stable silica sol when alkoxysilanes from different manufacturing lots are mixed. There were times when it disappeared.

By the way, as a method for hydrolyzing metal alkoxides, it has been proposed to use a catalytically effective amount of a solid hydrolysis catalyst selected from the group consisting of solid oxides of Group IIa metals and solid acid catalysts ( Japanese Patent Publication No. 58-108
．． 227 Publication), although this method allows the hydrolysis rate to be adjusted in the direction of increasing the hydrolysis rate, it is not possible to adjust the hydrolysis rate in the direction of decreasing the hydrolysis rate. , it could not be said that it was done in a sufficient manner.

[Means for Solving the Problems] The present invention has been devised in view of the above-mentioned viewpoints, and when performing a hydrolysis reaction of a metal alkoxide, the hydrolysis rate is adjusted to be slow and uniform. The present invention provides a method for hydrolyzing metal alkoxides that can produce stable sol.

That is, the present invention is based on the following general formula (1)% formula (1) (where M represents a metal atom, R and R- represent an alkyl group, an aryl group, an alkenyl group, or a hydrogen atom,
X and y are integers in which X is an integer of 0 to 3, y is an integer of 1 to 4, and their total x+y is 3 or 4. ) is a metal alkoxide hydrolysis method in which an aromatic amine is added to the reaction system as a hydrolysis rate retardant.

In the method of the present invention, the metal constituting the metal alkoxide represented by the above general formula (1) is a trivalent or tetravalent metal, specifically silicon, aluminum, titanium,
Examples include zirconium. Further, as the alkyl group which is the substituent R and R- of this metal alkoxide, methyl group, ethyl group, n-propyl group, isanopropyl group, n-butyl group, 1so-butyl group, 5ec-butyl group, Examples of the aryl group include a phenyl group, an alkyl group, and a substituted phenyl group substituted with a halogen, etc. Examples of the alkenyl group include a vinyl group, a 1-propenyl group, and an allyl group. , isopropenyl group, etc.

In addition, the aromatic amines added as hydrolysis rate retardants to the reaction system during the hydrolysis reaction of the metal alkoxides mentioned above include primary amines represented by aniline, and tertiary amines represented by diphenylamine and methylaniline. Examples include amines and tertiary amines represented by triphenylamine, dimethylaniline, pyridine, and the like. Any of these can be used, although there are varying degrees of effectiveness in retarding the reaction rate of the hydrolysis reaction.

The amount of aromatic amine added to the reaction system as a hydrolysis rate retardant depends on the type of metal alkoxide that is the target of the hydrolysis reaction and the acids and bases contained in this metal alkoxide that affect the hydrolysis rate. The type and content thereof vary depending on the hydrolysis rate of the metal alkoxide raw material to be subjected to the hydrolysis reaction, and are understood as the catalytic effective amount, which is usually 1% by weight or less. Regarding the amount of aromatic amine added, it is preferable to investigate in advance how it affects the hydrolysis rate of the raw material metal alkoxide, and then determine the hydrolysis rate suitable for the application based on the results. It is best to add it as follows.

Further, the aromatic amine used as the hydrolysis rate retardant can be used in combination with a hydrolysis catalyst to accelerate the hydrolysis rate, if necessary. That is, if the hydrolysis rate is too slow when no hydrolysis catalyst is used, but the hydrolysis rate becomes too fast when the hydrolysis catalyst is used, the hydrolysis catalyst and the aromatic amine The hydrolysis rate can be adjusted to a preferable rate for reaction control by adjusting the amount of each addition. Hydrolysis catalysts used for this purpose include conventionally known mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid, or formic acid;
Acids consisting of organic acids such as acetic acid, ammonium hydroxide,
Examples include bases such as quaternary ammonium hydroxide such as tetramethylammonium hydroxide, alkali or alkaline earth oxides or hydroxides, and acids are preferred.

[Function] According to the method of the present invention, the aromatic amine acts to slow down the hydrolysis rate of the metal alkoxide, and is used in combination with a hydrolysis catalyst that acts to accelerate the hydrolysis rate to perform the hydrolysis reaction. can be adjusted to the optimum condition.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples.

Example 1 Methyltrimethoxysilane 10 with a purity of 98-99% by weight prepared from methyltrichlorosilane and methanol
Pour d and 10 d of pure water into a 50 d glass container, h0
Pyridine is added as a water decomposition rate retardant in the proportion shown in Table 1, and stirred vigorously with a magnetic stirrer to completely hydrolyze the raw material methyltrimethoxysilane and the time required for the entire reaction system to become a uniform layer. (reaction time) was measured. The results are shown in Table 1.

Example 2 As the raw metal alkoxide, pure [98~5%] produced from the same methyltrimethoxysilane 7.5% as used in Example 1, tetrachlorosilane, and methanol was used as the raw material metal alkoxide.
A hydrolysis reaction was carried out in the same manner as in Example 1 above, except that 2.5% of 99% by weight tetramethoxysilane was used, and the reaction time was measured. The results are shown in Table 1.

Example 3 A hydrolysis reaction was carried out in the same manner as in Example 1 above, except that dimethylaniline was used instead of pyridine as a hydrolysis rate retardant, and the reaction time was measured. Results first
Shown in the table.

Example 4 A hydrolysis reaction was carried out in the same manner as in Example 1 above, except that aniline was used instead of pyridine as a hydrolysis rate retardant, and the reaction time was measured.

The results are shown in Table 1.

Table 1 Example 5 0.01N-HCJ20.1d was used as a hydrolysis catalyst, and if the hydrolysis reaction was not completed in 15 minutes, 1ml of 0.0IN-HCfflo was further added, and then every 5 minutes. The hydrolysis reaction was carried out in the same manner as in Example 1, except that if the hydrolysis reaction was not completed, 0.01N-HCI) and ld were added roughly, and the reaction time was measured. did. The results are shown in Table 2.

Example 6 A hydrolysis reaction was carried out in the same manner as in Example 5 above, except that 7.5d methyltrimethoxysilane and 2.5d tetramethoxysilane were used as the raw metal alkoxides in the same manner as in Example 2. , the reaction time was measured.

The results are shown in Table 2.

[Effects of the Invention] According to the method of the present invention, the hydrolysis reaction of metal alkoxides can be adjusted to slow down the hydrolysis rate, and as a result, even in the case of metal alkoxides that have a fast hydrolysis rate, a uniform and stable product can be produced. A sol can be produced, and the quality of inorganic materials produced using the sol as a raw material can be improved. In addition, by using in combination with a hydrolysis catalyst that acts to accelerate the hydrolysis rate, the hydrolysis rate of the metal alkoxide can be adjusted to a desired level.

Claims (2)

[Claims] (1) The following general formula (1) R′_xM(OR)_y(1) (However, in the formula, M represents a metal atom, R and R′ represent an alkyl group, an aryl group, an alkenyl group, or a hydrogen atom,
x and y are integers in which x is an integer of 0 to 3, y is an integer of 1 to 4, and their total x+y is 3 or 4. ) A method for hydrolyzing metal alkoxides, which comprises adding an aromatic amine as a hydrolysis rate retardant to the reaction system. (2) The method for hydrolyzing metal alkoxides according to claim 2, wherein the aromatic amine is pyridine, aniline, or dimethylaniline.