JPH08165114A - Production of transparent silica gel bulk substance containing methyl group - Google Patents

Abstract

PURPOSE: To simply produce the subject compound, useful as host materials for an organic substance having optical functions and excellent in mechanical properties, chemical durability and thermal stability by reacting a methyltrialkoxysilane (hereinafter referred to as A) with water in the presence of a metallic chelate compound (hereinafter referred to B), then baking the resultant reactional product and gelatinizing the baked product. CONSTITUTION: This method for producing the subject compound comprising a polysiloxane in which a network constituent unit represented by the formula CH3 SiO3/2 is repetitively bound so as to form a three-dimensional network structure. The ligand of the compound B comprises one or more of β-diketones, large ring polyether compounds, o,o'-dihydroxy aromatic azo compounds, etc., and the central metallic ions comprise one or more of Al, Cu, Zr, Cr, Co, Li, Na, K, rare earth metals and Ti. The amount of the added compound B is 0.001-5mol% based on the compound A. The amount of the water used is 1.4<=H2 O/Si<=4.0 expressed in terms of molar ratio. The pH just after preparing the reactional solution is 1.0-7.0.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a transparent silica gel bulk body containing a methyl group, and more particularly to a method for producing a transparent silica gel bulk body containing a methyl group which is useful as a host material for an organic substance having an optical function.

2. Description of the Related Art In the synthesis of glass, ceramics and the like by the sol-gel method, a large amount of solvent such as water and alcohol is usually used, so that the volume during drying is largely reduced, and particularly, a bulk body is produced. Sometimes it has the problem of cracking. Various methods for solving this problem have been proposed, but the gel body obtained is essentially porous, and a fundamental solution has not been reached yet. In addition, the synthesis of silica gel bodies doped with an organic substance having an optical function has been conventionally performed by the sol-gel method `` Tani et al, J. Appl. Phys. 58 (1985) 355.
9; Avnir et al, J. Phy. Chem. 88 (1984) 5956.
However, the skeleton structure of the matrix is often developed three-dimensionally, and the size of the gap in the skeleton was not sufficient to dope high-molecular-weight organic substances at high concentrations.

On the other hand, as silica gel bulk materials having a relatively large gap in the skeleton, those having a structural unit containing an organic group, those which are compounded with an organic polymer, and the like have been studied. It has not been possible to prepare a transparent bulk body having excellent physical properties, chemical durability, and thermal stability.

In the sol-gel method, it is known that precipitate formation or phase separation before gelation due to rapid hydrolysis reaction or solubility can occur, and the precipitation or phase separation phenomenon is caused by a methyl group-containing silica. It has also been reported in research on the production of coating films. Since precipitation formation and phase separation greatly affect the homogeneity of the gel body and impair the properties of the optical material, how to suppress these phenomena during the preparation of the matrix has been an issue.

The inventors of the present invention have conducted extensive research to solve the above problems, using organotrialkoxysilane as a raw material,
A method for producing a uniform organic group-containing transparent silica gel bulk body by the sol-gel method was found (Japanese Patent Application No. 6-87497), but a methyl group-containing transparent silica gel having a large gap in the skeleton and being particularly excellent in heat resistance. A complicated operation was required to obtain the bulk body.

Therefore, in the present invention, methyltrialkoxysilane is used as a raw material, and by the sol-gel method, the volume reduction during drying of the gel is extremely small, that is, cracks are not generated, and an organic substance having a large molecular weight is doped at a high concentration. A method to prepare an optically uniform methyl group-containing transparent silica gel bulk body that has a sufficient size of the skeleton to prevent the formation of gel before gelation and phase separation by a relatively simple operation. provide.

SUMMARY OF THE INVENTION The present invention provides a methyl group-containing transparent siligel bulk body composed of polysiloxane in which network constituent units represented by the formula: CH ₃ SiO _3/2 are repeatedly bonded so as to form a three-dimensional network structure. Manufacturing method. This methyl group-containing transparent silica gel bulk body is produced by a sol-gel method using methyltrialkoxysilane as a starting material.

According to the present invention, the polycondensation reaction of siloxane bond formation by hydrolysis and dehydration of methyltrialkoxysilane and dealcoholization condensation is carried out in the presence of a metal chelate compound soluble in methyltrialkoxysilane as a catalyst. Or after performing the reaction under neutral conditions, the reaction product is aged to be directly gelled.

During the reaction, suitable amounts of dialkoxysilane, tetraalkoxysilane, and their oligomers may be added individually or in admixture to the reaction system, if desired, so that the size of voids in the skeleton of the resulting silica gel bulk material and The polarity can be adjusted.

As described above, by using a metal chelate compound as a catalyst, a transparent methyl group-containing silica gel bulk body excellent in mechanical properties, chemical durability and thermal stability can be produced by a relatively simple operation. can do.

Preferred Embodiment As is well known, hydrolysis of an organodialkoxysilane produces a corresponding bifunctional silanol, and a dehydration condensation reaction produces a chain or cyclic polysiloxane. Since methyltrialkoxysilane produces trifunctional silanols, the resulting polysiloxane has a three-dimensional network structure in which the network constituent unit is CH ₃ SiO _3/2 due to its dehydration condensation reaction.

In this way, the network unit is C
By using H ₃ SiO _3/2 , the size of the gap in the skeleton of the matrix network becomes sufficiently large, and high-concentration doping of an organic substance having a large molecular weight becomes possible.

In the above method for producing a bulk silica gel containing a methyl group, methyltrimethoxysilane (M
Water and a metal chelate compound soluble in methyltrialkoxysilane are added to methyltrialkoxysilane such as TMS) and methyltriethoxysilane (MTES) to carry out a hydrolysis / polycondensation reaction. At this time, if no metal chelate compound is present, (CH ₃ SiO _3/2 ) _n crystals are precipitated. In addition, under alkaline conditions, the reaction mechanism changes, and particulate products precipitate, making it impossible to obtain a transparent silica gel bulk material.

The amount of water added is 1.4 ≦ H ₂ O / Si ≦ 4.
It is 0 (molar ratio). H ₂ O / Si <1.4 (molar ratio)
Then, unreacted alkoxy groups remain and the strength of the matrix deteriorates. On the other hand, when H ₂ O / Si> 4.0 (molar ratio), phase separation occurs and an optically homogeneous silica gel bulk body cannot be obtained. The amount of water added is 1.4 ≦ H ₂ O / Si ≦
More preferably, it is 2.5 (molar ratio).

It is not always necessary to remove the alcohol produced by the reaction, but it is preferable to use an open system in which the alcohol volatilizes during the aging after the reaction. Therefore, it is preferable not to add an organic solvent such as alcohol to the initial reaction solution.

The pH of the solution is preferably 1.0 to 7.0 as an initial value immediately after the reaction solution is prepared. If pH <1.0, the silica gel bulk body becomes cloudy even if the metal chelate compound is added. On the contrary, the desired reaction does not proceed under the condition of pH> 7.0. It is more preferable to add an acid catalyst to make the initial pH of the reaction solution 1.0 to 5.0 in order to accelerate the progress of the reaction, and therefore the acid catalyst to be used is not particularly limited,
Inorganic acid catalysts such as nitric acid and hydrochloric acid, and organic acid catalysts such as acetic acid are used according to a conventional method.

As the metal chelate compound, one that is soluble in methyltrialkoxysilane, which is the main raw material monomer, is used. When the metal chelate compound is insoluble in the raw material monomer and soluble in the aqueous phase, the desired reaction does not proceed.

As the chelate compound satisfying the above conditions, metal chelates of β-diketones (compounds having 1,3-dioxopropylene chain), macrocyclic polyether compound metal chelates, o, o′-dihydroxy aromatic azo Examples thereof include compound metal chelates, metal chelates of o-salicylidene aminophenol and its derivatives, and the like. The type of metal ion is not particularly limited, but it is necessary to select one having a large complex formation constant with the ligand. As a specific example, tris (acetylacetonato) aluminum (III
), Tris (ethylacetoacetato) aluminum (I
II), tris (diethylmalonato) aluminum (III
), Bis (acetylacetonato) copper (II), tetrakis (acetylacetonato) zirconium (IV), tris (acetylacetonato) chromium (III), tris (acetylacetonato) cobalt (III), and titanium oxide ( II) Acetylacetonato [(CH ₃ COCH ₂ COC
[H ₃ ) ₂ TiO] and other β-diketone metal chelates, rare earth metal diketone metal chelates, 18-crown-
6-potassium chelate compound salt, 12-crown-4-
Macrocyclic polyether compound metal chelates such as lithium chelate compound salts and 15-crown-5 sodium chelate salts, metal chelates of o, o'-dihydroxyazobenzene such as aluminum, cobalt, copper and titanium, o-salicylidene Aminophenolato copper (II), o-
Examples thereof include metal chelates such as salicylidene aminophenolato aluminum (III). It is considered that these metal chelate compounds interact with silanol to control the polymerization reaction. Regarding the addition amount, it is added in the range of 0.001 to 5 mol% with respect to the methyltrialkoxysilane depending on the effect. 0.
If it is less than 001 mol%, the effect of suppressing crystal precipitation cannot be obtained. On the other hand, if it is added in an amount of more than 5 mol%, a chelate compound will be deposited and the gel properties will be affected. The metal chelate compound may be prepared by adding a ligand component and a metal component separately to the reaction system and chelating in situ.
The addition amount of the metal chelate compound is more preferably 0.01 to 1 mol% with respect to methyltrialkoxysilane.

The chelate complex salt produced by coordinating a polyamine-based ligand such as ethylenediamine is soluble in the aqueous phase,
It is not preferable because it hinders the progress of the reaction and precipitates the chelate complex salt gradually. Further, when this kind of metal chelate compound is used, the pH shifts to the alkaline side and the reaction mechanism itself changes, so that the desired polymer cannot be obtained. Furthermore, if an acid is further added to adjust the pH to the acidic side, the chelate complex salt itself will precipitate.

The hydrolysis / polycondensation reaction may be carried out at room temperature, but it is preferably carried out at 40 to 80 ° C. to accelerate the reaction.

The silica gel bulk material containing a methyl group of the present invention has a R ¹ R ² SiO content of up to 40 mol%, preferably up to 30 mol%, in order to control the size and polarity of the voids in the skeleton.
_2/2 (R ¹ , R ² : methyl group, ethyl group, n-propyl group, isopropyl group, phenyl group, vinyl group, etc.) and / or SiO _4/2 unit may be contained. R ¹ R ² Si
When the O _2/2 unit exceeds 40 mol%, mechanical properties such as hardness deteriorate. When the SiO _4/2 unit exceeds 40 mol%, the contraction rate at the time of gelation becomes large, cracking is likely to occur, and chemical durability is deteriorated. R ¹ R ² SiO
_As the monomer forming the _2/2 unit, dialkoxysilane such as dimethyldimethoxysilane and diphenyldimethoxysilane is used, and as the monomer forming the SiO _4/2 unit, tetraalkoxysilane such as tetramethoxysilane and tetraethoxysilane is used. Silane is used. It is essential to use a metal chelate also when synthesizing a copolymer polymer, but this is a catalyst that suppresses crystal precipitation during polycondensation of a methyltrialkoxysilane monomer. Crystal precipitation is not observed even in the absence of a chelate catalyst. Therefore, the dialkoxysilane and / or the tetraalkoxysilane is reacted with water in the polycondensation reaction of the methyltrialkoxysilane, in the form of an alkoxysilane monomer, or in the absence of a metal chelate catalyst to obtain an oligomer obtained by the reaction. It can be added in the form and copolymerized.

The following examples are for the purpose of illustrating the invention and are not intended to limit the scope of the invention.

Example 1 Methyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-53)
0, hereinafter MTMS), 0.1 mol% of tris (acetylacetonato) aluminum (III) relative to MTMS was added, and distilled water was added so that the molar ratio of MTMS: H ₂ O was 1: 1.75. Was added. As 10 wt% water in distilled water, 0.1N nitric acid was used as a catalyst. Initially, it was in a two-phase state, but when stirring was continued at room temperature, it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 1 minute. At this time, the pH was 4.3. When left in a closed state for 2 weeks, no precipitate was observed. Then, it was opened at 40 ° C. to obtain a transparent gel body.

Comparative Example 1 MTMS has a molar ratio of distilled water to MTMS of 1.75: 1.
Distilled water was added so that 10 wt% in distilled water
As the water, 0.1N nitric acid was used as a catalyst. Initially, it was in a two-phase state, but when stirring was continued at room temperature, it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 1 minute. When left in a sealed state for 1 day, a precipitate was formed. The precipitate was centrifuged, was examined by powder X-ray diffraction, it was found to be C ₈ H ₂₄ Si ₈ O ₁₂ crystals. The upper liquid became a cloudy gel in two weeks.

Example 2 Methyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-18)
90, hereinafter MTES), distilled water was added so that the molar ratio of distilled water and MTES was 1.25: 1. As 10 wt% water in distilled water, 0.1N nitric acid was used as a catalyst. Initially it is in a two-phase state, but if stirring is continued at room temperature, it will become uniform as the hydrolysis / polycondensation reaction proceeds,
It became transparent within 10 minutes. After standing for 2 days in a sealed state, the theoretical value of alcohol produced by the reaction was 8
0% was evaporated by an evaporator to obtain an oligomer.
Further, 0.025 mol% of bis (acetylacetonato) copper (II) was added to MTES, and the mixture was kept at 50 ° C. for 30 minutes, and then 0.5 mol of distilled water was added per 1 mol of MTES. When stirring was continued in a sealed state, a blue transparent sol was obtained in about 30 minutes. After standing at 40 ° C., it became a blue transparent gel in 2 weeks. The dried gel was obtained at 40 ° C. in an open state. When examined by powder X-ray diffraction, no crystals could be detected.

Comparative Example 2 The oligomer of Example 2 was prepared by adding 0.1 mol% of copper sulfate to MTES at 50 ° C., 0.2 mol% of ethylenediamine, and 0.5 mol of distilled water per mol of MTES. Then, a copper ethylenediamine complex salt solution having a pH of 12 was added. When the mixture was stirred for 2 days in a sealed state, a copper chelate compound was precipitated in a two-phase liquid state.

Comparative Example 3 0.5 mol of distilled water was added to the oligomer of Example 2 at 50 ° C. per mol of MTES. The mixture was stirred in a sealed state, and a transparent sol was obtained in about 5 minutes. Then, when it was left still at 40 ° C. in a closed state, it became a cloudy gel in 2 days.

Comparative Example 4 To the oligomer of Example 2 was added 0.3 mol% of acetylacetone based on MTES at 50 ° C., and then 0.5 mol of distilled water was added per mol of MTES.
The mixture was stirred in a sealed state, and a transparent sol was obtained in about 5 minutes. Then, when it was left still at 40 ° C. in a closed state, it became a cloudy gel in 2 days.

Example 3 To the oligomer of Example 2, 0.1 mol% of tris (acetylacetonato) chromium (III) was added to MTES, and the mixture was kept at 50 ° C. for 30 minutes. Furthermore, MTES1
0.5 mol of distilled water was added per mol. When stirring was continued in a sealed state, a reddish purple transparent sol was obtained in about 20 minutes. After standing at 40 ° C., it became a reddish purple transparent gel in 2 days. In the open state, a dry gel was obtained. When examined by powder X-ray diffraction, no crystals could be detected.

Example 4 To the oligomer of Example 2, 0.1 mol% of tris (acetylacetonato) cobalt (III) with respect to MTES was added, and the mixture was kept at 50 ° C. for 30 minutes. Added 0.5 moles of distilled water. When stirring was continued in a sealed state, a green transparent sol was obtained in about 20 minutes.
Then, when it was left still at 40 ° C., it became a green transparent gel in 2 days. In the open state, a dry gel was obtained. When examined by powder X-ray diffraction, no crystals could be detected.

Example 5 The oligomer of Example 2 was mixed with 0.1 mol% based on MTES.
Tetrakis (acetylacetonato) zirconium (I
V) was added and kept at 50 ° C. for 72 hours, then MTES
0.5 mol of distilled water was added per mol. When stirring was continued in a sealed state, a colorless transparent sol was obtained in about 20 minutes. Then, when it was left still at 40 ° C., it became a transparent gel in 2 days. In the open state, a dry gel was obtained. When examined by powder X-ray diffraction, no crystals could be detected.

Example 6 The oligomer of Example 2 was mixed with 0.1 mol% based on MTES.
Aluminum sec-butoxide was added, and benzoyltrifluoroacetone was added in an amount of 0.3 mol%. 5
After holding at 0 ° C. for 30 minutes, the amount of 0.
Added 5 moles of distilled water. When stirring was continued in a sealed state, a colorless transparent sol was obtained in about 20 minutes. Then 4
After standing at 0 ° C., it became a transparent gel in 2 days. In the open state, a dry gel was obtained. When examined by powder X-ray diffraction, no crystals could be detected.

Example 7 The oligomer of Example 2 was mixed with 0.1 mol% based on MTES.
Aluminum sec-butoxide of
0.1 mol% of o'-dihydroxyazobenzene was added. After holding at 50 ° C. for 30 minutes, 0.5 mol of distilled water was added per mol of MTES. When stirring was continued in a sealed state, a red transparent sol was obtained in about 20 minutes. After that, when left standing at 40 ° C., a red transparent gel was formed in 2 days.

Example 8 Aluminum sec-butoxide and o-salicylidene aminophenol were dissolved in toluene so that each concentration was 0.1M. To the oligomer of Example 2, MT
The toluene solution was added so that the aluminum concentration was 0.025 mol% with respect to ES, and the mixture was held at 50 ° C. for 30 minutes, and then 0.5 mol of distilled water was added per 1 mol of MTES. When it was left still at 40 ° C. in a closed state, it became a brown transparent gel.

Example 9 The oligomer of Example 2 was mixed with 0.05 mol% of tris (acetylacetonato) europium (III) based on MTES.
) Was added. After holding at 50 ° C for 30 minutes, MTE
0.5 mol of distilled water was added per mol of S. 40 ° C
When left to stand in a closed state with, it became a yellow transparent gel in about 1 month.

Example 10 Tetraethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-234)
0, hereinafter TEOS), distilled water was gradually added so that the molar ratio of distilled water and TEOS was 1.5: 1. As 10 wt% water in distilled water, 0.1N nitric acid was used as a catalyst. Initially it is in a two-phase state, but if stirring is continued at room temperature, it will become uniform as the hydrolysis / polycondensation reaction proceeds,
It became transparent within 30 minutes. After standing for 2 days in a sealed state, the theoretical value of alcohol produced by the reaction was 6
Evaporation of 0% by an evaporator gave an oligomer of TEOS. To the oligomer of Example 2 was added 0.1 mol% of tris (acetylacetonato) aluminum (III) with respect to MTES, and the mixture was kept at 50 ° C. for 30 minutes.
0.5 mol of distilled water was added per mol of MTES.
After reacting for 40 minutes at 50 ° C. in a sealed state, TEOS oligomer was added to MTES oligomer so that the molar ratio of MTES and TEOS was 75:25.
Distilled water of 0.25 mol was added to 1 mol of Si in total of S and TEOS, and the mixture was reacted at 50 ° C. for 10 minutes. 40 ° C
Then, the mixture was allowed to stand in a closed state with, and a colorless transparent gel body was obtained in about 10 hours.

Example 11 The oligomer of Example 2 was mixed with 0.1 mol% of tris (acetylacetonato) aluminum (III) based on MTES.
) Was added and held at 50 ° C. for 30 minutes, then MTES
And dimethyldimethoxysilane (Shin-Etsu Chemical Co., LS-5
20, DMDM) DMDM was added so that the molar ratio was 90:10. Further, 0.65 mol of distilled water was added to 1 mol of Si in total of MTES and DMDM. In a closed state, stirring was continued and reaction was carried out for 1 hour. Then 4
After standing at 0 ° C., it became a colorless transparent gel in 2 days.

[Procedure amendment]

[Submission date] April 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

As the chelate compound satisfying the above conditions, metal chelates of β-diketones (compounds having 1,3-dioxopropylene chain), macrocyclic polyether compound metal chelates, o, o′-dihydroxy aromatic azo Examples thereof include compound metal chelates, metal chelates of o-salicylidene aminophenol and its derivatives, and the like. The type of metal ion is not particularly limited, but it is necessary to select one having a large complex formation constant with the ligand. As a specific example, tris (acetylacetonato) aluminum (II
I), tris (ethylacetoacetato) aluminum (III), tris (diethylmalonato) aluminum (III), bis (acetylacetonato) copper (II),
Tetrakis (acetylacetonato) zirconium (I
V), tris (acetylacetonato) chromium (II
I), tris (acetylacetonato) cobalt (II
I) and titanium (II) oxide acetylacetonate
_{[(CH 3} COCHCOCH 3) ₂ TiO] and the like of β- diketones metal chelate, a rare earth metal β- diketone metal chelate, 18-crown-6-potassium chelate compound salt, 12-crown-4-lithium chelate salt , Macrocyclic polyether compound metal chelates such as 15-crown-5-sodium chelate salt, o, o ′
-Metal chelates of dihydroxyazobenzene such as aluminum, cobalt, copper and titanium, metal chelates of o-salicylidene aminophenolato copper (II), o-salicylidene aminophenolato aluminum (III) and the like. it can. It is considered that these metal chelate compounds interact with silanol to control the polymerization reaction. Regarding the amount of addition, depending on the effect, it is 0.001 relative to methyltrialkoxysilane.
Add in the range of ˜5 mol%. If it is less than 0.001 mol%, the effect of suppressing crystal precipitation cannot be obtained. Conversely, 5 mol%
If added in a larger amount, the chelate compound will be precipitated and the gel properties will be affected. The metal chelate compound, the ligand component and the metal component are separately added to the reaction system,
It may be chelated in situ. The amount of the metal chelate compound added is 0.01-based on methyltrialkoxysilane.
More preferably, it is 1 mol%.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

The silica gel bulk material containing a methyl group of the present invention has a R ¹ R ² SiO content of up to 40 mol%, preferably up to 30 mol%, for controlling the size and polarity of the voids in the skeleton.
_2/2 (R ¹ , R ² : methyl group, ethyl group, n-propyl group, isopropyl group, phenyl group, vinyl group, etc.) and / or SiO _4/2 unit may be contained. R ¹ R ²
When the SiO _2/2 unit exceeds 40 mol%, mechanical properties such as hardness deteriorate. When the SiO _4/2 unit exceeds 40 mol%, the contraction rate at the time of gelation increases, cracking is likely to occur, and the chemical durability also deteriorates. R ¹ R ²
A dialkoxysilane such as dimethyldimethoxysilane or diphenyldimethoxysilane is used as the monomer forming the SiO _2/2 unit, and a tetraalkoxysilane such as tetramethoxysilane or tetraethoxysilane is used as the monomer forming the SiO _4/2 unit. Alkoxysilane is used. It is essential to use a metal chelate also when synthesizing a copolymer polymer, but this is a catalyst that suppresses crystal precipitation during polycondensation of a methyltrialkoxysilane monomer. Crystal precipitation is not observed even in the absence of a chelate catalyst. Therefore dialkoxysilane and /
Alternatively, tetraalkoxysilane is added to the reaction system during the polycondensation reaction of methyltrialkoxysilane in the form of an alkoxysilane monomer or in the form of an oligomer obtained by reacting with water in the absence of a metal chelate catalyst. It can be polymerized. Methyl group-containing transparent silica
The reaction product for obtaining a gel bulk body is glass before gelation,
For ceramics, crystallized glass, plastics, metals, etc.
It is also possible to coat the substrate to make a thin film
It The resulting film is more methyl-based than a silica coating.
Since it contains a vinyl group, it has excellent water resistance, electrical insulation, etc.
For insulating protective film of alkali-containing glass substrate and magnetic disk
Used to fill the pits of the alumite substrate used
To be As the coating method, dip coating,
Conventional methods such as spin coating and roll coating can be used.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

Example 11 The oligomer of Example 2 was prepared by adding 0.1 mol% of tris (acetylacetonato) aluminum (II) to MTES.
I) was added and the mixture was kept at 50 ° C. for 30 minutes, then MTES was added.
And dimethyldimethoxysilane (Shin-Etsu Chemical Co., LS-5
DMDM was added so that the molar ratio of ( 20, hereinafter DMDM) was 90:10. Further, 0.65 mol of distilled water was added to 1 mol of Si in total of MTES and DMDM.
In a closed state, stirring was continued and reaction was carried out for 1 hour. afterwards,
Upon standing at 40 ° C., a colorless transparent gel was formed in 2 days.

Claims (8)

[Claims] 1. A method for producing a transparent bulk silica gel containing a methyl group, which comprises polysiloxane in which network constituent units represented by the formula: CH ₃ SiO _3/2 are repeatedly bonded so as to form a three-dimensional network structure. And reacting methyltrialkoxysilane with water in the presence of a metal chelate compound soluble in methyltrialkoxysilane, and then aging the reaction product to cause gelation, thereby producing a bulk silica gel bulk body containing a methyl group. Method. 2. A total of 40 network building units which form a three-dimensional network structure of at least one of dialkoxysilane, tetraalkoxysilane and their oligomers.
The method of claim 1 including adding to the reaction system less than or equal to mol%. 3. The method according to claim 1, wherein the amount of the metal chelate compound added to methyltrialkoxysilane is 0.001 to 5 mol%. 4. The method according to claim 1, 2 or 3, wherein the amount of water used for the reaction is 1.4 ≦ H ₂ O / Si ≦ 4.0 (molar ratio) in the reaction system. 5. The initial pH immediately after preparation of the reaction solution is 1.0 to
The method according to any one of claims 1 to 4, which is 7.0. 6. The ligand of the metal chelate compound is selected from β-diketones, macrocyclic polyether compounds, o, o′-dihydroxy aromatic azo compounds, and o-salicylidene aminophenol and its derivatives. The method according to any one of claims 1 to 5, which is at least one kind. 7. The central metal ion of the metal chelate compound,
Aluminum, copper, zirconium, chromium, cobalt,
7. The method according to claim 1, wherein the method is at least one selected from ions of lithium, sodium, potassium, rare earth metals and titanium. 8. The method according to claim 1, wherein the methyltrialkoxysilane is reacted with water in the absence of an organic solvent.