JP3187907B2 - Method for producing hybrid silica gel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a hybrid silica gel having photochromic properties, and more particularly to a method for producing a photochromic hybrid silica gel having improved durability as a photochromic material.

[0002]

2. Description of the Related Art Conventionally, the sol-gel method is known as a method for synthesizing silica glass at a low temperature. The sol-gel method is a method in which a siloxane bond is formed from a raw material in a solution state by hydrolysis and polycondensation to form a silicon oxide. It is. In the case of producing a binary or higher oxide, a uniform copolymerized oxide can be produced because the raw materials can be mixed in molecular order. In addition, in the synthesis of silica glass by the melting method, a substance that decomposes at a high temperature, such as an organic substance, cannot be doped into the silica glass, but the glass is synthesized at a relatively low temperature by the sol-gel method that performs solution mixing. Since it is possible, it is possible to dope the silica glass with an organic substance. Using this method, studies have been conducted in which silica gel is doped with various dyes. For example, Makishima et al. (J. Am. Ceram. Soc, 69 (4) 198)
6), Tani et al. (J. Appl. Phys., 58 (9) 1. Nov. 1985), David AVN
This is introduced in IL et al. (J. Non. Cry. Solids, 74, 1985, 395).

[0003] We have long been conducting research into doping functional silica into silica gel particles. Until now, silica gel was doped with a functional dye such as a photochromic compound, and the function was successfully expressed in silica gel. Furthermore, it has been found that elution of the photochromic compound from the silica gel can be prevented by chemically immobilizing the silica gel with a photochromic compound having an alkoxysilyl group.

[0004]

However, it has been newly found that the photochromic compound immobilized in silica gel by the above method may have a reduced durability. As a result of the examination, the cause was estimated as follows. When organic substances are contained, a large amount of hydroxyl groups remain in the silica gel because heat treatment cannot be performed at high temperatures, and the amount of acid sites in the silica gel is considerably large.
It corresponds to pH 3-4. Therefore, the doped photochromic compound is liable to be deteriorated. In particular, in the case of the photochromic compound, the deterioration reaction is accelerated by light irradiation, and oxidative deterioration is remarkable. Therefore, conventional silica gels exhibiting photochromic properties are not yet practically sufficient in terms of durability, and it is important to solve these problems.

[0005] An object of the present invention is to reduce the acid sites or reduce the acid strength of silica gel as a method of suppressing the deterioration of the photochromic compound immobilized in the hybrid silica gel.

[0006]

The inventor of the present invention has conducted intensive studies to solve the problems of the prior art as described above.
We succeeded in improving the durability of the photochromic properties of silica gel doped with a compound exhibiting photochromic properties by chemically immobilizing the compound by controlling the acid strength of the silica gel.

That is, the present invention relates to a compound represented by the general formula (1) or (2): Si (OR ¹ ) ₄ (1) (wherein R ¹ represents a hydrogen atom or an alkyl group.) R ² _n Si (OR ³ ) _4-n (2) (wherein, R ² represents an alkyl group, an alkenyl group, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or 2). Silicon alkoxide to be reacted with a photochromic compound having an alkoxysilyl group to synthesize silica gel,
Next, the silica gel is subjected to a general formula (3) M (OR) n (3) (where M is an alkali metal atom or an alkaline earth metal atom, n is the valence of the metal M, R is a hydrogen atom or an alkyl group) Each of which is treated with an alkali metal compound represented by the following formula:

[0008] Another invention provides a method for producing a compound of the formula: M (OR) n (3) wherein M is an alkali metal atom or an alkaline earth metal atom, in the presence of an alkali metal compound represented by the general formula (3). n represents the valence of the metal M, and R represents a hydrogen atom or an alkyl group.) Formula (1) or (2) Si (OR ¹ ) ₄ (1) (wherein, R ¹ is a hydrogen atom or an alkyl group) R ² _n Si (OR ³ ) _4-n (2) (wherein, R ² represents an alkyl group, an alkenyl group, or a phenyl group; R ³ represents a hydrogen atom or an alkyl group; Is an integer of 1 or 2). A method for producing a photochromic hybrid silica gel, comprising reacting a silicon alkoxide represented by the formula (1) with a photochromic compound having an alkoxysilyl group.

Hereinafter, the present invention will be described in detail.

[0010] The photochromic hybrid silica gel of the present invention (hereinafter referred to as photochromic gel) is a so-called sol-gel method in which a silica gel is chemically incorporated into silica gel with the purpose of imparting photochromic properties to silica gel with an organic compound exhibiting photochromic properties. Refers to a material in which a photochromic compound is dispersed and contained in molecular units or clusters while being fixed in a fixed manner. The shape of the photochromic gel is not limited at all, and may take any form such as a thin film, a bulk gel, a fiber, a particle and the like.

As the silicon alkoxide represented by the general formula (1) used in the production method of the present invention, R ¹ is a methyl group, an ethyl group, a propyl group, a butyl group, etc. Propoxysilane, tetrabutoxysilane and the like can be mentioned.

In the silicon alkoxide represented by the general formula (2) also used for the production, R ² is an alkyl group, an alkenyl group or a phenyl group. Examples of the alkyl group include a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a decyl group, and an octadecyl group. Examples of the alkenyl group include a linear or branched alkenyl group such as an ethenyl group, a propenyl group, a butenyl group, and a hexenyl group. R ³ represents an alkyl group, and preferably includes the same substituents as those exemplified for R ¹ .

Specific examples of the silicon alkoxide of the general formula (2) include phenyltrimethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane,
Ethyltrimethoxysilane, propyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n-
Octadecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, amyltriethoxysilane, n-octyltriethoxysilane, n-octadecyltriethoxysilane, n-dotesyltriethoxysilane, methyltributoxysilane, ethyltributoxy Examples thereof include silane, ethyltripropoxysilane, vinyltriethoxysilane, allyltriethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, and vinylmethyldiethoxysilane.

Although the silicon alkoxide of the general formula (1) and the silicon alkoxide of the general formula (2) may be used alone, those of the general formula (1) improve the strength of the photochromic gel and improve the physical durability. Since each of the general formula (2) has the effect of reducing the acid point of the photochromic gel and improving the chemical durability,
They can be used in combination at any ratio depending on the desired physical properties of the silica gel.

The photochromic compound having an alkoxysilyl group (hereinafter referred to as a silyl group-containing photochromic compound) used in the present invention is not particularly limited as long as it has an alkoxysilyl group co-hydrolyzable with silicon alkoxy in the molecule. However, various organic photochromic compounds can be used. For example, compounds obtained by introducing an alkoxy group into a photochromic compound such as azobenzenes, spiropyrans, and spiroxazines are preferably used. The compound group is specifically exemplified below, but is not limited thereto.

[0016]

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[0017]

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Since the above photochromic compound has an alkoxysilyl group in the molecule, it is condensed with the silicon alkoxide by hydrolysis to form a Si—O—Si bond, which is chemically bonded to silica gel. it can.

In M (OR) n represented by the general formula (3) used in the production method of the present invention, M is an alkali metal atom or an alkaline earth metal, n is the valence of the metal M, R is
Represents a hydrogen atom or an alkyl group, respectively. Specifically, when R is an alkyl group, lithium methylate, lithium ethylate, lithium propionate, sodium methylate, sodium ethylate, sodium propinate, potassium methylate, potassium ethylate, potassium propinate, magnesium dimethoxide , Calcium dimethoxide, barium dimethoxide, strontium dimethoxide, calcium dimethoxide and the like. Among these, solid substances are preferably used by dissolving them in a solvent such as alcohol in order to progress the reaction treatment uniformly.

When R is hydrogen, examples include lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydroxide, barium hydroxide and the like. Also in this case, it is preferable to use an aqueous solution or an alcohol solution.

The photochromic gel of the present invention is produced by the following two methods.

In the first method, the coexistence of the alkali metal compound represented by the general formula (3) is carried out by the general formula (1) or (2).
Is produced by reacting a silicon alkoxide represented by the formula (1) with a silyl group-containing photochromic compound and performing a co-hydrolysis and condensation reaction. This method is a so-called sol-gel method, and a known method is adopted without any limitation.

For example, the above three compounds are reacted in an aqueous solution of an acidic alcohol at a pH of 2-3 at a molar ratio of 10 to 40, and co-hydrolysis and condensation are carried out. Specifically, a silicon alkoxide and a silyl group-containing photochromic compound are partially reacted in an acidic alcohol aqueous solution to form an oligomer, and then 1 to 0.01 mole of an alkali metal compound is added to 1 mole of the silicon alkoxide. After mixing with the alcohol solution, the reaction is further advanced to produce a photochromic gel. If the amount of the alkali metal compound exceeds the above range, the silica gel is dissolved and the matrix itself tends to be affected, which is not preferable. If it is less than the above range, the effect of addition is small.
Of course, co-hydrolysis and condensation of the silicon alkoxide and the silyl group-containing photochromic compound may be performed in an aqueous acidic alcohol solution containing an alkali metal compound in advance.

The former method of once producing an oligomer is preferably employed because various forms of photochromic gel can be produced as described in detail below.

For example, when producing a particulate photochromic gel, a mixed solution containing the above-mentioned alkali metal compound and oligomer is dropped into a 10 to 20-fold volume ammonia water-alcohol solution at pH 10 to 13 to prepare an emulsion. A method is employed in which the solid is converted into a liquid, and the obtained solid is collected by centrifugation or the like. In the case of producing a bulk photochromic gel, for example, a method in which the mixed solution is placed in a container having a small hole and allowed to stand, the reaction is allowed to proceed, and the solvent is gradually evaporated is preferable. Furthermore, a thin-film photochromic gel can be produced by dip-coating or spin-coating the mixed solution on a substrate.

The amount of the silyl group-containing photochromic compound to be used is not particularly limited and can be used in any ratio, but it is usually used in a molar amount of 0.2 to 1 times the total amount of the silicon alkoxide.

A reaction solvent is usually used for the purpose of allowing the hydrolysis and condensation reactions to proceed uniformly, but alcohols are preferably used. This alcohol includes methanol,
Examples include ethanol, propanol, and butanol.

As described above, it is a preferred embodiment to use an acidic catalyst such as hydrochloric acid, sulfuric acid, acetic acid and citric acid and a basic catalyst such as sodium hydroxide and ammonia to promote the hydrolysis and condensation reactions. . Water is a component necessary for the hydrolysis reaction, and the amount of water used is appropriately selected depending on the amount of the hydrolyzate, the form of the obtained photochromic gel, and the like.

The hydrolysis temperature is not particularly limited as long as the added silyl group-containing photochromic compound does not decompose. The higher the temperature, the faster the hydrolysis proceeds. However, when an acidic catalyst is added at the time of the hydrolysis, a high temperature promotes oxidative degradation, so that the temperature is preferably about 10 to 60 ° C.

After the hydrolysis, heat treatment is usually performed to remove water and alcohol remaining in the gel. The heat treatment temperature varies depending on the target product to be produced, but is not particularly limited as long as the photochromic function of the photochromic compound portion is not lost. Usually, 100 ~
Treated at 200 ° C.

Another method for producing the photochromic gel of the present invention is to react a silicon alkoxide represented by the general formula (1) or (2) with a silyl group-containing photochromic compound, and then perform a hybrid reaction once by a cohydrolysis and condensation reaction. This is a method in which silica gel is produced and then subjected to a reaction treatment with an alkali metal compound represented by the general formula (3).

For example, a silicon alkoxide represented by the general formula (1) or (2) is mixed with an organoalkoxysilane and a silyl group-containing photochromic compound at pH 2-3.
The oligomer obtained by hydrolysis with an aqueous acidic alcohol solution is further reacted to form a hybrid silica gel, and then reacted with an alkali metal compound represented by the general formula (3).

Usually, the two are reacted in an organic solvent such as an alcohol, and then the solvent is removed. The shape of the hybrid silica gel is not particularly limited, such as a thin film and particles. In the case of particles, it is preferable to disperse particles to be treated in a solvent before mixing with an alcohol solution of an alkali metal compound. A method of performing ultrasonic treatment for a certain period of time to sufficiently disperse the particles is also preferable.

In the second production method, the production conditions such as the solvent, catalyst, hydrolysis temperature, heat treatment temperature and the like in the previous production method are similarly employed. However, when the silicon alkoxide of the general formula (1) and the silicon alkoxide of the general formula (2) are used in combination, if the amount of the latter is large, particles of the latter alone tend to be formed. ４０40 mol%.

The second production method is a preferred method, since the hybrid silica gel is treated with an alkali metal compound after production, so that the treating agent does not affect the synthesis of the silica gel itself, but a large-sized bulk photochromic gel is produced. In such a case, it is difficult to treat the inside even if it is a porous body, so the first manufacturing method is suitably adopted. In the case of a thin-film or particulate photochromic gel, an equivalent one can be obtained regardless of which method is adopted.

When an alkali metal compound in which R is an alkyl group is used, the compound reacts with water and immediately reacts with M.
The second production method is preferably adopted when it is necessary to produce silica gel in an aqueous solution system because it easily becomes (OH) n.

[0037]

The photochromic gel produced by the present invention reduces the acid sites in the silica gel and reduces the acid strength by reacting the silica gel during or after the production of the silica gel in the presence of an alkali metal compound. It is a thing. As a result, it is possible to prevent the deterioration of the compound part exhibiting photochromic characteristics, which is liable to cause deterioration, and to improve the durability of the photochromic characteristics.

Of course, since the photochromic compound is chemically bonded to silica gel and fixed, the photochromic compound does not elute with an organic solvent or the like. Furthermore, when a silicon alkoxide of the general formula (1) and a silicon alkoxide of the general formula (2) are used in combination as a raw material for silica gel, the gel itself has sufficient strength and is excellent in solvent resistance and heat resistance. For example, photochromic hybrid silica gel particles produced using only the silicon alkoxide of the general formula (2) swell in ethanol, dissolve in tetrahydrofuran, and have a melting point around 160 ° C. On the other hand, the hybrid silica gel particles prepared by using 10 mol% of the silicon alkoxide of the general formula (1) are not dissolved in ethanol and do not have a melting point until the organic groups burn. In addition, when 30 mol% is used in combination, it does not dissolve in tetrahydrofuran.

[0039]

The present invention will be described more specifically with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

Example 1 2 g of tetraethoxysilane and spirooxazine (a)
A solution prepared by dissolving 0.24 g in 20 ml of ethanol was added with pH 3
Of hydrochloric acid was added and stirred at 25 ° C. for 5 hours. To the reaction solution was added 1.1 g of a methanol solution containing 28% by weight of sodium methoxide, and the mixture was further stirred for 30 minutes.
The reaction solution was added dropwise to an ammonia water alcohol solution (25% ammonia water 11.2 ml, ethanol 56 ml) with stirring. The produced solid was separated by centrifugation, washed with water and ethanol, and dried at 120 ° C. for 4 hours to obtain photochromic gel particles having a particle size of 0.2 to 0.4 μm.

When the surface acid strength of the silica gel particles was measured by an indicator method, the pKa was 5 to 6, and the acid strength was low.

Polymethyl methacrylate (PMMA) 2
g was dissolved in 40 ml of dioxane, and a dispersion of 0.02 g of the photochromic gel particles prepared in the above method and 2 ml of dioxane were mixed, followed by ultrasonic treatment, and 1 ml of the prepared solution was placed in a petri dish. The cast dioxane was evaporated to produce a cast film. Xe lamp is continuously irradiated on this PMMA film,
The PMMA film was taken out every 30 minutes and the absorbance based on the photochromic reaction was measured. The results are shown in FIG. In this figure, the ratio of the absorbance to the initial absorbance based on the absorbance immediately after the start of irradiation is used as the absorbance. In the figure, by comparison with Comparative Example 1 described later, it is recognized that the photochromic gel of the present invention doubles the time when the absorbance reaches 60% of the initial absorbance, and has improved light durability.

When the obtained photochromic gel was subjected to Soxhlet extraction using ethanol, the same photochromic properties as before extraction were exhibited after extraction.

Comparative Example 1 2 g of tetraethoxysilane and spirooxazine (a)
A solution of 0.24 g in ethanol 20 ml was added with pH
3.6 ml of an aqueous hydrochloric acid-ethanol solution (0.2 m
l) was added and the mixture was stirred at 25 ° C for 5 hours. The reaction solution was treated with an aqueous ammonia-ethanol solution (25% aqueous ammonia 1).
1.2 ml, ethanol 56 ml) with stirring. The resulting solid was separated from the reaction solution by centrifugation, washed with water and ethanol, and dried at 120 ° C. for 4 hours to obtain silica gel particles having photochromic properties.

When the surface acid strength of the silica gel particles was measured in the same manner as in Example 1, the pKa was 3-4. or,
A cast film was prepared in the same manner as in Example 1, and the change over time in absorbance was measured. Fig. 1 shows the results.
It was shown to.

Example 2 2 g of tetraethoxysilane and spirooxazine (a)
A solution prepared by dissolving 0.24 g in 20 ml of ethanol was added with pH 3
Of hydrochloric acid was added and stirred at 25 ° C. for 5 hours. 1.1 g of a methanol solution containing 28% by weight of sodium methoxide was added to the reaction solution, and the mixture was further stirred for 30 minutes. The reaction solution was covered with a small perforated lid and the solvent was gradually developed. It was dried sufficiently to form a xerogel, and then dried at 120 ° C. for 4 hours to produce a photochromic gel.

The pKa of this photochromic gel was 6. After crushing this photochromic gel once,
When formed into pellets and subjected to continuous irradiation in the same manner as in Example 1, the half-life of the absorbance was 1.8 times that of the silica gel of Comparative Example 2 prepared using only tetraethoxysilane described below. Extended.

Comparative Example 2 20 g of tetraethoxysilane and spirooxazine (a)
A solution prepared by dissolving 2.4 g in 20 ml of ethanol was added to a solution having a pH of 3.
Of hydrochloric acid solution (2.5 ml of water)
Stirred at C for 15 hours. The reaction solution was allowed to stand, and a small perforated lid was placed thereon, and the solvent was gradually evaporated. After sufficient drying to form a xerogel, the mixture was dried at 120 ° C. for 4 hours to prepare silica gel.

Pellets were prepared from the silica gel in the same manner as in Example 2, and the change in absorbance with time was examined.

Example 3 A reaction solution containing sodium methoxide prepared in the same manner as in Example 2 was dip-coated on a clean glass substrate. After the solvent was volatilized, heat treatment was performed at 120 ° C. for 10 minutes. After cooling, dip coating was performed again.
After repeating this operation 10 times, heat treatment was performed at 120 ° C. for 4 hours to obtain a gel film.

The gel film had a pKa of 5-6. Further, when the Xe lamp was continuously irradiated in the same manner as in Example 1, the half-life of the absorbance was 2.1 times as compared with the film of Comparative Example 3 produced using only tetraethoxysilane described later. there were.

Comparative Example 3 A gel film was obtained from the reaction solution containing no sodium methoxide prepared in the same manner as in Comparative Example 2 by the same dip coating method as in Example 3. The change with time of the absorbance based on the photochromic reaction of the film was examined in the same manner as in Example 3.

Example 4 2 g of tetraethoxysilane and spirooxazine (a)
A solution of 0.24 g in ethanol 20 ml was added with pH
3.6 ml of an aqueous solution of hydrochloric acid in ethanol-water (0.2 ml of water)
l) was added and the mixture was stirred at 25 ° C for 5 hours. The reaction solution was treated with an aqueous ammonia-ethanol solution (25% aqueous ammonia 1).
(1.2 ml, ethanol 56 ml) with stirring, followed by separation, washing and drying to produce hybrid silica gel particles. 0.6 g of the silica gel particles were dispersed in 20 ml of a methanol solution containing 3.24 × 10 ^-2 g of sodium methoxide, and subjected to sonication for 1 hour. The particles were collected by centrifugation, washed with water and ethanol, and then heat-treated at 120 ° C. for 4 hours to obtain photochromic gel particles.

The photochromic gel particles have a pKa of 5
Met. Further, a PMMA film was produced in the same manner as in Example 1, and the light durability was examined. As a result, silica gel particles produced in the same manner as in this example (pKa = 3 to 4) except that treatment was not performed with sodium methoxide. P prepared from
It was found that the half-life of the absorbance was 1.7 times that of the MMA film, and the light durability was improved.

Example 5 2 g of tetramethoxysilane, 2 g of allyltrimethoxysilane and 0.45 g of spiropyran (e) were added to methanol 2
To the solution dissolved in 0 ml, 3.6 ml of a hydrochloric acid-methanol aqueous solution of pH 2 (0.2 ml of water) was added, and the mixture was stirred at 25 ° C for 5 hours. The reaction solution was dip-coated on a clean glass substrate. After the solvent was volatilized, heat treatment was performed at 120 ° C. for 10 minutes, and after cooling, dip coating was performed again, and this operation was repeated 10 times to obtain a film. The film was immersed in 20 ml of an aqueous solution containing 1.4 × 10 ^-2 g of lithium hydroxide for 1 hour,
Heat treatment was performed at 4 ° C. for 4 hours to obtain a photochromic gel film. The film exhibited photochromic activity in which it was colored by irradiation with ultraviolet light and decolored by irradiation with visible light. Further, the half-life of the absorbance was 1.5 times that of a sample not immersed in a lithium hydroxide aqueous solution, and it was found that the light durability was improved.

Example 6 2 g of tetraethoxysilane and 0.2 of azobenzene (g)
To a solution of 4 g in 20 ml of ethanol was added 3.6 ml of a hydrochloric acid-ethanol solution of pH 3 (0.2 ml of water), and the mixture was stirred at 25 ° C for 5 hours. The reaction solution was added to an aqueous ammonia-alcohol solution (11.2 ml of 25% aqueous ammonia,
The mixture was dropped into ethanol (56 ml) with stirring, separated, washed and dried to prepare hybrid silica gel particles. 0.6 g of the silica gel particles were dispersed in 20 ml of an aqueous solution containing 3.0 × 10 ^-2 g of potassium hydroxide, and subjected to ultrasonic treatment for 1 hour. The particles were collected by centrifugation, washed with water and ethanol, and dried at 120 ° C. for 4 hours to obtain photochromic gel particles.

When the photochromic gel particles were alternately irradiated with ultraviolet light and visible light, it was observed that the photochromic properties due to cis-trans photoisomerization proceeded promptly.

Further, a PMMA film was prepared from the silica gel particles in the same manner as in Example 1, and the change with time in the absorbance was examined. As a result, the half-life was 1.7 as compared with the case not treated with potassium hydroxide. Doubled.

Example 7 A solution prepared by dissolving 2.1 g of phenyltriethoxysilane and 0.45 g of spiropyran (e) in 20 ml of ethanol was added with 4.5 ml of an aqueous solution of hydrochloric acid at pH 3, and the solution was added at 25 ° C.
Stir for 5 hours. The reaction mixture was added with tetraethoxysilane 0.1.
8 g was added and the mixture was further stirred for 5 hours. The reaction solution was treated with an aqueous ammonia-alcohol solution (25% aqueous ammonia 11.2).
After stirring, the mixture was dropped into a mixture of ethanol and 56 ml of ethanol), separated, washed and dried to prepare hybrid silica gel particles. 0.6 g of the silica gel particles were dispersed in 20 ml of an aqueous solution containing 1.4 × 10 ⁻² g of lithium hydroxide, and subjected to ultrasonic treatment for 1 hour. Collect the particles by centrifugation, wash with water and ethanol,
For 4 hours to obtain photochromic gel particles.

A PMMA film was prepared using the photochromic gel particles in the same manner as in Example 1, and the light durability was examined. As a result, the half life of absorbance was 1. It was four times larger.

[Brief description of the drawings]

FIG. 1 shows PMMA containing photochromic (hybrid silica) gel particles produced in Example 1 and Comparative Example 1.
It is a figure which shows the time-dependent change of the light absorbency based on the photochromic reaction of a film.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 77/04 C08G 77/06 C08G 77/26 C08G 77/32 C08G 77/388 C09K 9/02

Claims (2)

(57) [Claims] 1. General formula (1) or (2) Si (OR ¹ ) ₄ (1) (wherein R ¹ represents a hydrogen atom or an alkyl group.) R ² _n Si (OR ³ ) _4-n (2) (wherein, R ² represents an alkyl group, an alkenyl group, or a phenyl group, R ³ represents a hydrogen atom or an alkyl group, and n represents an integer of 1 or 2). Is reacted with a photochromic compound having an alkoxysilyl group to synthesize silica gel,
Next, the silica gel is subjected to a general formula (3) M (OR) n (3) (where M is an alkali metal atom or an alkaline earth metal atom, n is the valence of the metal M, R is a hydrogen atom or an alkyl group) Each of which is treated with an alkali metal compound represented by the following formula: 2. In the presence of an alkali metal compound represented by the general formula (3), M (OR) n (3) wherein M is an alkali metal atom or an alkaline earth metal atom, and n is a metal. R represents a hydrogen atom or an alkyl group, respectively.) General formula (1) or (2) Si (OR ¹ ) ₄ (1) (wherein, R ¹ represents a hydrogen atom or an alkyl group) _{^{.) R 2 n Si (oR}} 3) 4-n (2) ( wherein, R ² represents an alkyl group, an alkenyl group or a phenyl group,, R ³ represents a hydrogen atom or an alkyl radical, n is 1 or Wherein the silicon alkoxide represented by the formula (2) is reacted with a photochromic compound having an alkoxysilyl group.