JPS63229146A - Catalyst used for sol-gel method of metallic alkoxide and sol-gel method used therewith - Google Patents

Abstract

PURPOSE:To shorten gelling time by preparing a catalyst used for a sol-gel method of metallic alkoxide from both mineral acid or its anhydride and tertiary amine substantially insoluble in water and soluble in an organic solvent. CONSTITUTION:A catalyst for converting metallic alkoxide into sol-gel is prepared from both mineral acid or its anhydride and tertiary amine substantially insoluble in water and soluble in a organic solvent. Sol-gel is obtained by hydrolyzing metallic alkoxide while using the above-mentioned catalyst and also subjecting the hydrolysate to polycondensation and converting it into a high polymer. As the metallic alkoxide, Si(OC2H5)4 and Al(O-iso-C3H7)3, etc., are used. Further as tertiary amine, N-dimethylbenzilamine, tributhylamine and tri-n-propylamine, etc., are used.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to a metal alkoxide sol that can be gelled in a short time under normal temperature and neutral conditions and can form a crack-free dry gel. This invention relates to a gel method catalyst and a sol-gel method using the same.

(Prior Art) In recent years, a glass synthesis method (sol-gel method) using metal alkoxides has been attracting attention. In this method, metal alkoxide is hydrolyzed and polycondensed to achieve polymerization. The sol-gel method uses an alkyl solution of metal alkoxide.

A certain amount of water and mineral acids, organic acids, inorganic bases (e.g.

By adding a catalyst such as NaOH, KOH) or ammonia,
It is carried out in the range of room temperature to 80°C. Hydrolysis reaction and polycondensation reaction of metal alkoxide occur simultaneously. In this method, glass can be obtained at a relatively low temperature, so the cost is reduced, and it can also be used to prepare composite materials with metals, plastics, etc.

In this sol-gel method, mineral acids, organic acids, inorganic bases,
A method was adopted in which only one type of catalyst, such as ammonia, was used. In systems using such a single catalyst, gelation requires a long time of 24 to 700 hours. Furthermore, the degree of polymerization of the hydrolyzed alkoxide is not constant due to factors such as volatilization of alcohol or water used as a solvent during gelation. As a result of partially different degrees of polymerization, cracks are likely to occur in the resulting dry gel (glass).

Several attempts have been made to produce high-quality glass in a short time using the sol-gel method.
JP-A No. 60-27611 discloses that an aqueous solution of silica alkoxide is hydrolyzed by adding an acid to it.

A method is disclosed in which a gel is prepared by adding a base to adjust the pH to 5 to 6 after the decomposition reaction is completed.

JP-A-60-215532 discloses a method in which a metal alkoxide is hydrolyzed using an acid and an alkali, and after the hydrolysis, these are mixed to obtain a gel. In JP-A-57-7814, an acid is added as a catalyst to a solution in which a metal alkoxide is dissolved in a small amount of water-alcohol mixture.

A method is disclosed in which a water-alcohol mixture is added while refluxing, and finally a base is added to form a gel. When these methods are employed, gelation is completed in a relatively short time (several tens of minutes to several hours). However, the resulting gel is not necessarily uniform, and cracks are likely to occur when the gel is dried. On the other hand, in JP-A-59-116135, a sol containing ultrafine particles is prepared in advance by hydrolyzing a metal alkoxide, and this is added to a metal alkoxide solution.

A method of hydrolysis and polymerization using conventional methods is disclosed. According to this method, cracks are relatively less likely to occur, but it is still insufficient and a substantially homogeneous gel cannot be obtained.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to achieve uniform desired quality in a short time in a sol-gel process for metal alkoxides. It is possible to prepare wet gels.

The object of the present invention is to provide a sol-gel method catalyst that does not cause cracks when drying the wet gel, and a sol-gel method using the same.

(Means for solving the problem) The inventors employed a specific tertiary amine as a catalyst in addition to the conventionally known acid catalyst (mineral acid or its anhydride) in the sol-gel process for metal alkoxides. By doing so,
It has been found that the gelation time can be significantly shortened and that the gelation time can be adjusted arbitrarily. Furthermore, since a homogeneous gel is produced by employing such a catalyst, cracks do not occur due to drying of the gel. One of the present inventions was completed based on such knowledge of the inventors.

The metal alkoxide sol-gel process catalyst of the present invention contains a mineral acid or its anhydride and an organic base.

The organic base is a tertiary amine that is substantially insoluble in water and soluble in organic solvents, thereby achieving the above objective.

In the sol-gel method of the present invention, a metal alkoxide is hydrolyzed using a catalyst and simultaneously polycondensed.

A sol-gel method including polymerization, using a mineral acid or its anhydride and an organic base as the catalyst,
The organic base is a tertiary amine that is substantially insoluble in water and soluble in organic solvents.

This achieves the above objective.

The metal alkoxide used in the present invention includes:

For example, Si (OCJs) a, 81 (O-iso
-CJt)i+Ti(O-iso-C3H?)41
Zr(O-t-CJq)4, Zr(O-n-C4Hq
), Ca(O-CJ5)z, Fe(OCJs)+,
V(O-iso-C3117)at 5n(O-t-
C,H,)a.

Li(OC2H5)+ Be(OCJs)z+ B(O
CtHs)z, P(OCJs)+ and P(OClh)
There is +.

Hydrochloric acid, sulfuric acid, nitric acid, etc. are used as mineral acids for the catalyst. A similar effect can be obtained using an anhydride of mineral acid 1, such as hydrogen chloride gas. In addition, organic acids and their anhydrides can also be used. These include phthalic anhydride, maleic anhydride, dodecylsuccinic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, dichlorosuccinic anhydride and chlorendic anhydride. be. These acids are used in an amount of 0.01 mol or more, preferably 0.01 to 0.5 mol, per 1 mol of metal alkoxide. If the amount is too small, hydrolysis of the metal alkoxide will hardly proceed.

The base used as a catalyst is an organic base.

Moreover, it is a tertiary amine that is substantially insoluble in water and soluble in organic solvents. Such tertiary amines include N
, N-dimethylbenzylamine, tributylamine,
Tri-n-propylamine, tripentylamine, tripropargylamine, N, N.

Examples include N-trimethylethylenediamine and tri-n-hexylamine. Tertiary amine is.

It is used in an amount equivalent to or more than the above acid, preferably in a ratio of 0.01 to 0.06 mol per mol of metal alkoxide. The amount of the tertiary amine to be used is appropriately determined within the above range depending on its degree of dissociation.

If the amount of tertiary amine is too small, the polycondensation reaction after hydrolysis of the metal alkoxide will be extremely slow.

As the solvent used when performing the sol-gel method, in addition to water used for hydrolysis, organic solvents are used. As the organic solvent, a solvent that is miscible with water or partially soluble in water is used. For example, methanol, ethanol.

These include butanol, propatool, pentanol, hexanol, acetone, methyl ethyl ketone, and formamide. Various additives may also be used when carrying out the sol-gel process. Examples of additives include silver halide, barium titanate, transition metals, and chalcogen elements. Various monomers and polymers.

By adding bisphenol A, epichlorohydrin, a coupling agent, etc., an organic-inorganic composite material can be prepared. By adding fragrance essences, dyes, and pigments, aromatic gels and colored gels can be prepared.

Using these sol-gel method catalysts, the sol-gel method of metal alkoxides is carried out in a second, for example, first order manner.

First, a metal alkoxide is dissolved in the above organic solvent such as alcohol. Add a certain amount of water and mineral acid (or its anhydride) among the above sol-gel method catalysts to this, and
Heat to 0°C. This substantially completes the hydrolysis. Further, a tertiary amine of the sol-gel method catalyst of the present invention is added to this reaction solution. When the tertiary amine is added, the polycondensation reaction proceeds within a short time and gelation is completed.

The gelation time depends on the amount of water and the amount of sol-gel catalyst used. Usually, it is possible to adjust the gelation time in the range of 2 seconds to several tens of minutes from the time when the mineral acid is neutralized by the addition of tertiary amine and reaches pH 7.

In the method of the present invention, the amount of the sol-gel method catalyst used in the 9 reactions is sufficient as described above. Therefore, the 9 reaction system is kept almost neutral.

The hydrolysis reaction and polycondensation reaction of alkyl silicate using the sol-gel method catalyst of the present invention are considered to be as follows. First, a hydrolysis reaction of alkyl silicate proceeds with mineral acid.

When a tertiary amine is added to this, the next reaction proceeds.

(ROh Si OH+ R2H-1 → (RO)3
Si O−+ R2H”H(II)(RO)3
Si OH+ R2H“H->(RO)i Si
” + R2H+ 820 (I[)(II
) and (III) (RO)z Si
O- and (ROhSi") undergo polycondensation, and the final result is an inorganic polymer compound: or its analogue. Theoretically, in order to form a linear polymer, water should be Although the amount of water is 1 mole, it is a well-known fact that 2 moles or more of water is required to form a crosslinked polymer with cross-linking between the polymers.

Among the above reactions, the metal alkoxide hydrolysis reaction (1) is considered to be an SN2 reaction based on recent experimental results by the inventors. In order to proceed with this reaction in the right direction, 1) remove the alcohol (ROH) produced as a result of the reaction from the reaction system to reduce its concentration; or 2) withdraw the hydroxyl group or hydrogen of (RO)3StOll produced. 9. It is important to allow the polymerization reaction to proceed.

In the present invention, a tertiary amine acts on the compound of formula (I), and as shown in formulas (■) and (II[), (RO
)3St O- and (RO)3-Si'' are produced, which undergo chain polycondensation to rapidly produce the polymer compound (IV).

It is thought that the reaction will proceed in the same way even if other inorganic bases or other amines are used in place of the tertiary amine. However, most of these other bases have water-soluble properties. When these water-soluble bases are added to the reaction solution, the mineral acids in the reaction solution are neutralized at once, so the polycondensation reaction proceeds at high density around the area where the base is dropped or injected.

The resulting gel will be non-uniform. This tendency is particularly strong when the above-mentioned water-soluble base is dissolved in water and added, and the gel becomes partially cloudy or cloudy high-density particles are non-uniformly dispersed in the gel. When such a gel is dried, cracks are likely to occur.

In contrast, the base used in the present invention is a tertiary amine that is substantially insoluble in water. This tertiary amine is uniformly dispersed in the reaction solution, partially dissolved in water due to the presence of the mineral acid, and the solution is neutralized, after which it reacts with the hydrolyzed metal alkoxide hydroxide and undergoes polycondensation. form a high molecular compound.

Although the reaction is extremely rapid, compared to when using the above-mentioned water-soluble base, after being uniformly dispersed in the solution,
In order to carry out the above reaction, a homogeneous polymer compound is formed throughout the reaction solution. Of the tertiary amines used in the present invention, N
, N-dimethylbenzylamine forms particularly homogeneous gels and high quality glasses (dry gels) are prepared.

(Example) The invention will be explained below with reference to examples.

1 plate ethyl silicate (Si (OCgHs) 4) 26
g was dissolved in ethanol 22 relative. To this solution, 0.03 mol of hydrochloric acid and 16 mol of water were added and mixed with respect to 1 mol of the ethylsilicate to perform hydrolysis. Five seconds after the above hydrochloric acid and water were added, 0.06 mol of N,N-dimethylbenzylamine dissolved in advance in ethanol was added all at once to the stirring liquid mixture.

Gelation occurred in 3 seconds, producing a colorless and transparent homogeneous gel. Since surface hardening of this wet gel occurs immediately, formamide was injected 5 minutes after gelation to relieve the vapor pressure of ethanol exuding from the wet gel, and the wet gel was allowed to stand for one hour. Furthermore, ethanol was released in a constant temperature bath at 60°C. Gradually raise the temperature of the constant temperature bath and dry at 150°C for 6 hours.

A transparent dry gel was obtained. This was heated to 800°C under N2 atmosphere.
A silica glass lump with a specific gravity of about 2.1 without cracks was obtained by heat treatment at a temperature of 1050°C to 1050°C.

The procedure was the same as in Example 1 except that the amount of disaster relief water was 10 moles. Gelation occurred 5 seconds after addition of N,N-dimethylbenzylamine. A silica glass lump having the same quality as that of Example 1 was obtained.

The procedure was the same as in Example 1 except that the amount of water used was 8 mol. After adding N,N-dimethylbenzylamine, 10
Gelation occurred after seconds. A silica glass lump having the same quality as that of Example 1 was obtained.

26 g of Seiran Goto ethyl silicate (Si(OCJs) 4) was dissolved in ethanol 22ytR. This solution contains 0.03 mol of H per 1 mol of the ethyl silicate.
CI and 1 mole water were added and mixed. N after 5 seconds,
0.06 mol of N-dimethylbenzylamine was added in advance to ethanol 3rId1. was added all at once to the above stirring liquid mixture. This was heated to 60° C. with stirring to obtain a viscous solution after 1 to 1.5 hours. The viscosity was between 10 poise and 5 poise. Ethanol to this
5th addition of formamide (50/'50) mixture,
The viscosity was adjusted to about 10 poise to 50 poise, and a viscous thread was pulled out using a glass rod. After exposing it to moisture in the air, 9 elastic fibers were continuously collected. This is N
Firing was performed in a two-gas atmosphere (800-1050°C) to obtain highly pure silica glass fibers.

(Effects of the Invention) According to the present invention, the gelation time of metal alkoxide in the sol-gel method is thus significantly shortened. Gelation is achieved in a few seconds, rather than the hundreds of hours required in the past. The gelation time can be easily adjusted in the range of several seconds to several tens of minutes by changing the amount of the sol-gel method catalyst.The zero reaction is carried out near neutrality, and a small amount of catalyst is sufficient. The wet gel obtained is homogeneous, so that no cracks occur when drying the wet gel. When the resulting gel is fired, a strong inorganic polymer compound is formed. Aromatic gels and colored gels can be prepared by adding fragrance essences, dyes, and pigments to metal alkoxides.

Furthermore, if the gelation of the metal alkoxide is performed simultaneously with the polymerization of the organic monomer, a composite material in which inorganic and organic materials are combined on a molecular scale can be obtained.

that's all

Claims (1)

[Claims] 1. A metal alkoxide sol containing a mineral acid or its anhydride and an organic base, where the organic base is a tertiary amine that is substantially insoluble in water and soluble in organic solvents. - Gel method catalyst. 2. The tertiary amine is N,N-dimethylbenzylamine, tributylamine, tri-n-propylamine, tripentylamine, tripropargylamine, N,N,N
The catalyst according to claim 1, which is at least one selected from the group consisting of -trimethylethylenediamine and tri-n-hexylamine. 3. The metal alkoxide is Si(OC_2H_5)
_4, Al(O-iso-C_3H_7)_3, Ti(
O-iso-C_3H_7)_4, Zr(O-t-C_
4H_9)_4, Zr(O-n-C_4H_9)_4,
Ca(OC_2H_5)_2, Fe(OC_2H_5
)_3, V(O-iso-C_3H_7)_4, Sn(
O-t-C_4H_9)_4, Li(OC_2H_5)
, Be(OC_2H_5)_2, B(OC_2H_5
)_3, P(OC_2H_5)_3 and P(OCH_
3) The catalyst according to claim 1, which is at least one selected from the group consisting of _3. 4. A sol that includes hydrolyzing metal alkoxide using a catalyst and polycondensing it to polymerize it.
A gel method, in which a mineral acid or its anhydride and an organic base are used as the catalyst, and the organic base is a tertiary amine that is substantially insoluble in water and soluble in an organic solvent. Gel method. 5. The tertiary amine is N,N-dimethylbenzylamine, tributylamine, tri-n-propylamine, tripentylamine, tripropargylamine, N,N,N
The sol-gel method according to claim 4, wherein the sol-gel method is at least one selected from the group consisting of -trimethylethylenediamine and tri-n-hexylamine. 6. The metal alkoxide is Si(OC_2H_5)
_4, Al(O-iso-C_3H_7)_3, Ti(
O-iso-C_3H_7)_4, Zr(O-t-C_
4H_9)_4, Zr(O-n-C_4H_9)_4,
Ca(OC_2H_5)_2, Fe(OC_2H_5
)_3, V(O-iso-C_3H_7)_4, Sn(
O-t-C_4H_9)_4, Li(OC_2H_5)
, Be(OC_2H_3)_2, B(OC_2H_5
)_3, P(OC_2H_5)_3 and P(OCH_
3) The sol-gel method according to claim 4, which is at least one member selected from the group consisting of _3.