JPH07277760A - Transparent bulk silica material containing organic group and its production - Google Patents

Abstract

PURPOSE:To provide a transparent bulk silica material having three-dimensional network structure and large voids to enable the doping of an organic substance having optical function at a high concentration. CONSTITUTION:This bulk silica material is composed of a polysiloxane composed of a recurring network constitution unit expressed by formula RSiO3/2(R is an organic group bonded to a silicon atom through a carbon atom) bonded with each other to form a three-dimensional network structure. The material is produced by the hydrolysis and dehydrative and/or dealcoholative polycondensation reaction of an organotrialkoxysilane having a corresponding organic group in the absence of an alcoholic solvent.

Description

Detailed Description of the Invention

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

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 alcohol is usually used, so that the volume is greatly reduced during drying, and cracks are generated especially when a bulk body is manufactured. Has the problem of entering. Various methods for solving this problem have been proposed, but the obtained gel body is essentially porous, and a fundamental solution has not been reached yet.

Further, "Tani et al, J. App," which has been conventionally used to synthesize a silica gel body doped with an organic substance having an optical function, by a sol-gel method.
l. Phys. 58 (1985) 3559; Avnir.
et al, J .; Phy. Chem. 88 (198
4) 5956. In many cases, the skeleton structure of the matrix is three-dimensionally developed, 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, in the sol-gel method, it is known that a rapid hydrolysis reaction, a precipitation and the like before gelation or a phase separation phenomenon due to solubility can occur. The phase separation phenomenon has also been reported in a study on the production of a silica coating film containing a methyl group. Precipitation and phase separation greatly affect the homogeneity of the gel body and impair the properties of the optical material. Therefore, how to suppress these phenomena during the preparation of the matrix has been an issue.

Therefore, the present invention uses organotrialkoxysilane as a raw material, and by the sol-gel method, the volume reduction of the gel during drying is extremely small, that is, cracks are not generated and an organic substance having a large molecular weight is also highly concentrated. It is an object of the present invention to prepare a transparent bulk silica material having a uniform organic group, which has a sufficient size of a skeleton in the skeleton to be doped, and is free from precipitation before gelation and phase separation.

SUMMARY OF THE INVENTION The present invention relates to an organic-group-containing transparent silica bulk body composed of polysiloxane in which network constituent units represented by the formula: RSiO _3/2 are repeatedly bonded so as to form a three-dimensional network structure. . In the formula, R is an organic group bonded to a silicon atom by a carbon atom, typically methyl, ethyl, n-
Hydrocarbon groups such as propyl, isopropyl, phenyl and vinyl.

The organic group-containing transparent silica bulk material is
The organotrialkoxysilane of the formula: RSi (OR ′) ₃ (R ′ is a lower alkyl group such as methyl or ethyl) can be used as a starting material and can be produced by the sol-gel method.

According to the present invention, an alcohol solvent is not used in the polycondensation reaction for forming a siloxane bond by hydrolysis, dehydration and dealcoholization of the organotrialkoxysilane. Then, in the first method, after a theoretical amount or excess (1.5 ≦ H ₂ O / Si ≦ 3.0 in a molar ratio) of water is added to the organotrialkoxysilane at one time and reacted. The reaction product is aged and gelled in an open system. In the second method, the initial reaction is performed with water that is less than the theoretical amount (1.0 ≦ H ₂ O / Si <1.5 in molar ratio), and the theoretical amount or excess (molar ratio) is added from the first time until the final time. At a rate of 1.5 ≦ H ₂ O / Si ≦ 2.0), and the cumulative amount of water is 1.5
At any stage prior to <H ₂ O / Si, at least 50% total by-product alcohol is removed, after which the reaction is aged and gelled in an open system.

Preferred Embodiment As is well known, when an organodialkoxysilane is hydrolyzed, a corresponding bifunctional silanol is produced, and a chain condensation or a cyclic polysiloxane is produced by a dehydration condensation reaction. 3 for organotrialkoxysilane
Since the functional silanol is produced, the polysiloxane produced by the dehydration condensation reaction has a three-dimensional network structure in which the network constitutional unit is RSiO _3/2 (R is the same as above).

In this way, the network unit is R
By using SiO _3/2 , the size of the gap in the skeleton of the network of the matrix becomes sufficiently large, and high-concentration doping of an organic substance having a large molecular weight becomes possible. The contained organic group R is typically a hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a phenyl group and a vinyl group, and, of course, contains two or more kinds of organic groups. It may be. Even if an organic group having a higher carbon number is introduced, the gelation time becomes too long. In order to increase the size of the gap in the skeleton, the methyl group is most preferable, but it may be appropriately selected depending on the type and amount of the organic substance to be doped.

In the method for producing a transparent silica bulk body containing an organic group, when a methyl group is not contained as the organic group R, an alcohol solvent is not added to the starting material and RS is used.
i (OR ′) ₃ (R and R ′ are the same as above) 1.5 ≦
Water is added so that H ₂ O / Si ≦ 3.0 (molar ratio), and a hydrolysis / polycondensation reaction is performed. At this time, if the alcohol is contained in a large amount, crystals of (RSiO _3/2 ) _n will be precipitated. The amount of water added is H ₂ O / Si <1.5
At (molar ratio), unreacted alkoxy groups remain and the strength of the matrix deteriorates. Conversely, H ₂ O / Si> 3.0
At (molar ratio), phase separation occurs and an optically homogeneous silica bulk body cannot be obtained. The aging after the reaction is performed in an open system so that the alcohol generated by the reaction is volatilized. Crystallization and / or precipitation can be suppressed by advancing the reaction by the above method, and a desired silica bulk material can be obtained.

When methyl is contained as the organic group R in the method for producing a transparent silica bulk material containing an organic group, an alcohol solvent is not added to the starting material, and partial hydrolysis with water less than the theoretical amount is carried out. -It is necessary to remove at least 50% of the alcohol produced by the polycondensation reaction from the system. Here, the generated alcohol is removed from the system at a temperature not higher than the boiling point of the alcohol. It is preferable that a small amount of alcohol remains in order to obtain a uniform solution in the second and subsequent additions of water, but if a large amount of alcohol is contained, (RSiO _3/2 ) _n crystals are formed as the reaction progresses. Is deposited. In this method, water is added in two or more stages. The amount of water added in the first stage is 1.0 ≦ H ₂ O /
Si <1.5 (molar ratio). H ₂ O / Si <1.0
Then, when the generated alcohol is removed from the system, unreacted monomers are also volatilized. Conversely, H ₂ O / Si ≧ 1.5
Then crystallization occurs. Finally, the added amount of water is 1.5 ≦ H ₂ O / Si ≦ 2.0 (molar ratio) in terms of integration from the first step.
To do so. The total amount of water is H ₂ O / Si <
At 1.5 (molar ratio), unreacted alkoxy groups remain, and the strength of the matrix deteriorates. Conversely, H ₂ O / Si> 2.
At 0, phase separation occurs and an optically homogeneous silica bulk body cannot be obtained. In the stepwise addition of water, it is necessary to remove at least 50% of the by-produced alcohol in total at any stage before the cumulative amount of water becomes 1.5 ≦ H ₂ O / Si. is there. The aging after the reaction is performed in an open system so that the alcohol generated by the reaction is volatilized. By proceeding the reaction by the above method, crystallization and / or precipitation formation can be suppressed, and a desired silica bulk material can be obtained.

The starting material solution contains the organotrialkoxysilane, water and a catalyst, and the catalyst is nitric acid,
An inorganic acid catalyst such as hydrochloric acid, an organic acid catalyst such as acetic acid, and a base catalyst such as ammonia are used according to a conventional method.

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.

Specific examples of the organotrialkoxysilane of the formula RSi (OR ') ₃ include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltriethoxysilane, Vinyltriethoxysilane or the like can be used. As the carbon number of R increases, it becomes more difficult to form crystals, but the methyl group is most preferable for the structure of the network. Therefore, it is appropriately selected according to the type and amount of the organic substance to be doped.

Example 1 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% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 10 minutes. After standing at the same temperature for 2 days in a sealed state, the alcohol produced by the reaction was evaporated under reduced pressure of 80% of the theoretical value, and 0.5 mol of distilled water was further added to 1 mol of MTES. After stirring and reacting for 2 hours at an internal temperature of 40 to 50 ° C in a sealed state, the mixture was opened and left in a drier at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Example 2 MTES has a molar ratio of distilled water to MTES of 1.33: 1.
Distilled water was added so that As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 10 minutes. After standing still at the same temperature for 2 days in a sealed state, the alcohol produced by the reaction was evaporated under a reduced pressure of 80% of the theoretical value, and further 0.
Added 17 moles of distilled water. Inner temperature 40 ~ in a sealed state
After reacting at 50 ° C for 2 hours, the mixture was opened and left in a dryer at 40 ° C. The obtained gel body is transparent and powder X
Crystals could not be detected even by line diffraction.

Example 3 MTES has a molar ratio of distilled water to MTES of 1.33: 1.
Distilled water was added so that As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 10 minutes. The obtained solution was allowed to stand still at the same temperature for 2 days in a sealed state, the alcohol produced by the reaction was evaporated under reduced pressure of 80% of the theoretical value, and 0.67 mol of distilled water per mol of MTES was further added. Then, it was made to react for 2 hours at an internal temperature of 40 to 50 ° C. in a sealed state. During this time, gelation occurred. Further, it was opened and left in a dryer at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Comparative Example 1 Distilled water was added to MTES so that the molar ratio of distilled water and MTES was 1.5: 1. As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 10 minutes. When left in a sealed state at room temperature for 6 months, a precipitate having a particle size of several μm was formed at the bottom of the gel. When examined by powder X-ray diffraction, it was found to be C ₈ H ₂₄ O ₁₂ Si ₈
It was found to be crystalline. The gel layer was cloudy, and the precipitation of crystals was confirmed.

Comparative Example 2 MTES has a molar ratio of distilled water and MTES of 1.25: 1.
Distilled water was added so that As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 10 minutes. The obtained solution was allowed to stand in the sealed state at the same temperature for 2 days, and then the alcohol produced by the reaction was evaporated under reduced pressure of 80% of the theoretical value, and MTES1 was added.
Added 1.0 mole distilled water per mole. Then, it was made to react for 2 hours at an internal temperature of 40 to 50 ° C. in a sealed state. During this time, gelation occurred. Further, when opened and left in a dryer at 40 ° C., a cloudy gel was finally obtained. When examined by powder X-ray diffractometry, no crystals could be detected.

Example 4 Methyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-53)
0, hereinafter MTMS), distilled water was added so that the molar ratio of distilled water and MTMS was 1: 1. 10w of distilled water
For t%, 0.1N nitric acid was used as a catalyst. Initially, it is in a two-phase state, but if stirring is continued at an internal temperature of 40 to 50 ° C,
It became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 1 minute. After left standing in the sealed state at the same temperature for 2 days, the alcohol produced by the reaction was evaporated under reduced pressure of 80% of the theoretical amount, and further, it was adjusted to 0.
Added 25 moles of distilled water. 30 more in a sealed state
After reacting for 1 minute at the same temperature, the alcohol produced by the reaction is evaporated again under reduced pressure of 80% of the theoretical amount, and MT
0.5 mol of distilled water was added per mol of MS. After the reaction was carried out for 2 hours at an internal temperature of 40 to 50 ° C. in a sealed state, the mixture was opened and left in a dryer at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Example 5 Ethyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-24)
Distilled water was added to 10, ETES hereinafter) so that the molar ratio of distilled water to ETES was 1.75: 1. As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 30 minutes. After left standing in the sealed state at the same temperature for 2 days, it was opened and left in a drier at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Example 6 Ethyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-24)
10, hereinafter referred to as ETES), distilled water was added so that the molar ratio of distilled water and ETES was 2.5: 1. 1 of distilled water
For 0 wt% water, 0.1 N nitric acid was used as a catalyst. Initially, it was in a two-phase state, but when stirring was continued at an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 30 minutes. After left standing in the sealed state at the same temperature for 2 days, it was opened and left in a dryer at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Example 7 Vinyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-23)
00, hereinafter VTES), distilled water was added so that the molar ratio of distilled water to VTES was 1.5: 1. 1 of distilled water
For 0 wt% water, 0.1 N nitric acid was used as a catalyst. Initially, it was in a two-phase state, but when stirring was continued at an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 30 minutes. After left standing in the sealed state at the same temperature for 2 days, it was opened and left in a dryer at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Example 8 Phenyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., LS-4)
480, hereinafter referred to as PTES), distilled water was added so that the molar ratio of distilled water and PTES was 1.5: 1. As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 30 minutes. After left standing in the sealed state at the same temperature for 2 days, it was opened and left in a dryer at 40 ° C. The obtained gel body was transparent, and crystals could not be detected by powder X-ray diffraction.

Comparative Example 3 Distilled water was added to PTES so that the molar ratio of distilled water and PTES was 1.5: 1. As 10 wt% of 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 an internal temperature of 40 to 50 ° C., it became uniform as the hydrolysis / polycondensation reaction proceeded, and became transparent within 30 minutes. When left in a sealed state at room temperature for 6 months, the solution did not gel and precipitation of crystals was observed.

Example 9 The transparent gel body obtained in Example 1 was subjected to the following measurements. The thermal stability was examined by DTA-TG,
At around 400 ° C., a weight loss accompanied by heat dissipation was observed. 40
It was thermally stable up to 0 ° C. When the Abbe refractive index was measured, the refractive index of the dried gel was 1.412.

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[Procedure amendment]

[Submission date] December 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 9

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The starting material solution contains the organotrialkoxysilane, water and a catalyst, and the catalyst is nitric acid,
An inorganic acid catalyst such as hydrochloric acid and an organic acid catalyst such as acetic acid are used according to a conventional method.

Claims (9)

[Claims] 1. A network constitutional unit represented by the formula: RSiO _3/2 (R is an organic group bonded to a silicon atom by a carbon atom) comprises a polysiloxane which is repeatedly bonded so as to form a three-dimensional network structure. Organic group-containing transparent silica bulk material. 2. The silica bulk body according to claim 1, wherein R is a hydrocarbon group. 3. The silica bulk body according to claim 2, wherein the hydrocarbon group is at least one selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, vinyl and phenyl. 4. An organotrialkoxysilane of the formula: RSi (OR ') ₃ (R is an organic group bonded to a silicon atom by a carbon atom, R'is a lower alkyl group) is reacted with water in the absence of an alcohol solvent. The method for producing a silica bulk body according to claim 1, wherein the reaction product is aged and gelled in an open system. 5. To the organotrialkoxysilane containing no alcohol solvent, 1.5 ≦ H ₂ O / Si ≦ 3.
The method according to claim 4, wherein 0 (molar ratio) of water is added and reacted, and then the reaction product is aged and gelled in an open system. 6. The organotrialkoxysilane containing no alcoholic solvent is 1.0 ≦ H ₂ O / Si for the first time.
<1.5 (molar ratio), water was added at least twice so that the total was 1.5 ≦ H ₂ O / Si ≦ 2.0 (molar ratio) from the first time by the last time. At least 5 times in total at any stage before the cumulative amount of water becomes 1.5 ≦ H ₂ O / Si.
The method according to claim 4, wherein the reaction product is aged and gelled in an open system after the removal to the outside of 0% system. 7. The method according to claim 5, wherein R of the organotrialkoxysilane is at least one of ethyl, n-propyl, isopropyl, vinyl and phenyl. 8. The method according to claim 6, wherein R of the organotrialkoxysilane is at least one of methyl, ethyl, n-propyl, isopropyl, vinyl and phenyl. 9. The method according to claim 4, wherein the reaction between the organotrialkoxysilane and water is carried out in the presence of a catalytic amount of an acid or a base.