JPH05140313A - Production of hybrid silica gel - Google Patents

Abstract

PURPOSE:To obtain a hybrid silica gel hardly eluting a photochromic compound in an organic solvent, having high durability as a photochromic material. CONSTITUTION:A silicon alkoxide (e.g. tetramethoxysilane or tetraethoxysilane) of formula I (R<1> is alkyl) or a silicone alkoxide (e.g. phenyltrimethoxysilane) of formula II (R<2> is alkyl, alkenyl, etc.; R<3> is alkyl; (n) is 1 or 2) and an alkoxysilyl group-containing photochromic compound are co-hydrolyzed and condensed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing hybrid silica gel having photochromic properties by a sol-gel method.

[0002]

2. Description of the Related Art Conventionally, the sol-gel method has been known as a low temperature synthesis method for silica glass, and a siloxane bond is formed from a raw material in a solution state by hydrolysis and polycondensation reaction to form a silicon oxide. Is. In the case of producing a binary or higher oxide, the raw materials can be mixed in a molecular order, and thus a uniform copolycondensed oxide can be produced. Further, 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 sol-gel method of solution mixing synthesizes glass at a relatively low temperature. As a result, it is possible to dope organic substances into the silica glass.

On the other hand, so-called inorganic-organic hybrid materials for fixing organic dyes to inorganic oxides such as silica and alumina have been considerably studied, and stabilization and improvement of dye functions have been studied. However, an organic photochromic compound, which is one of the organic dyes, is a compound that exhibits photochromism by an isomerization reaction, a reversible bond cleavage reaction, or the like. Therefore, unlike ordinary dyes, they are easily affected by the reaction field.For example, in spiropyran-containing hybrid silica gel prepared by hydrolyzing tetraethoxysilane in the presence of spiropyran exhibiting photochromism, the influence of acidic protons in the silica gel It showed reverse photochromism or no photochromic properties.

[0004]

[Problems to be Solved by the Invention] We have been researching the doping of functional organic substances into silica gel particles. So far, we have succeeded in doping silica gel particles with a functional dye such as a photochromic compound, and to express the function in silica gel, and have already proposed. However, in the produced silica gel, since the doped dye and silica gel do not undergo chemical bonding, when the produced silica gel particles are dispersed in an organic solvent, the functional dye is eluted from the silica gel particles into the solvent. was there.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems of the prior art, the present inventors have found that the doped photochromic compound is eluted from silica gel even in an organic solvent. We succeeded in producing a hybrid silica gel that has no That is, the present invention provides the following general formula (1) or (2) Si (OR ¹ ) ₄ (1) (wherein R ¹ represents 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 an alkyl group, and n represents an integer of 1 or 2), and A method for producing a photochromic hybrid silica gel, which comprises co-hydrolyzing and condensing a photochromic compound having an alkoxysilyl group.

In the present invention, silica gel is produced by a so-called sol-gel method, which is a low temperature synthesis method of glass from a solution containing silicon alkoxide as a raw material.

The silicon alkoxide represented by the general formula (1) of the present invention includes tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane in which R ¹ is a methyl group, an ethyl group, a propyl group, a butyl group or the like, and Specific examples include tetrabutoxysilane and the like.

In the silicon alkoxide represented by the general formula (2), R ² represents an alkyl group, an alkenyl group or a phenyl group. As the alkyl group,
It is a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group, and an alkenyl group is an ethenyl group, a propenyl group, a butenyl group,
It is a linear or branched alkenyl group such as a pentenyl group. R ³ represents an alkyl group, and examples thereof include 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-dodecyltriethoxysilane, methyltributoxysilane, ethyltributoxysilane , Ethyltripropoxysilane, vinyltriethoxysilane, allyltriethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldiethoxysilane and the like.

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

[0011]

[Chemical 1]

[0012]

[Chemical 2]

Since the above photochromic compound has an alkoxysilyl group, it is hydrolyzed to cause polycondensation with a silicon alkoxide to generate a Si--O--Si bond, which can be chemically bonded to silica gel.

The method of co-hydrolyzing and condensing the silicon alkoxide represented by the general formula (1) or (2) and the silyl group-containing photochromic compound for producing the hybrid silica gel of the present invention is a known so-called sol. -A method called gel method is adopted without any limitation.

For example, first, a silicon alkoxide represented by the general formula (1) or (2) and a silyl group-containing photochromic compound are hydrolyzed with an aqueous acidic alcohol solution having a pH of 2 to 3 and a molar ratio of 10 to 40. In the reaction, the silyl group-containing photochromic compound is generally mixed with a silicon alkoxide for hydrolysis, and then the silicon alkoxide and the compound are partially condensed to form an oligomer. With this oligomer,
The condensation is further promoted by the method described below to produce various forms of silica gel. For example, as a method for producing particulate silica gel, a solution containing the oligomer is adjusted to pH 10 to 10
A method in which a solid solution obtained by dropping 13 into an aqueous ammonia-alcohol solution having a volume of 10 to 20 times to obtain an emulsion and collecting the obtained solid by centrifugation or the like is suitably used. Further, in the case of producing bulk silica gel, for example, a method in which an oligomer solution is placed in a container having small holes and allowed to stand still to gradually evaporate the solvent is suitable. Further, a thin-film silica gel can be produced by dip-coating or spin-coating an oligomer solution on a substrate.

The amount of the silyl group-containing photochromic compound to be cohydrolyzed is not particularly limited, and it can be used in an arbitrary ratio with respect to the silicon alkoxide, but it is usually used in a molar amount of 0.2 to 1 times. The order of addition of both compounds is not particularly limited, but since the silicon alkoxide and the silyl group-containing photochromic compound used generally have different hydrolysis rates, when combining those having different hydrolysis rates into an oligomer, the hydrolysis rate is It is preferable to adjust the progress of hydrolysis by adding the slower one first and the later one the earlier one.

The hydrolysis temperature is not particularly limited as long as it does not decompose the added silyl group-containing photochromic compound. The higher the temperature is, the faster the hydrolysis proceeds, but when an acidic catalyst is added during the hydrolysis, high temperature promotes oxidative deterioration, so about 10 to 60 ° C. is preferable. The heat treatment temperature for removing water and alcohol remaining in the gel after hydrolysis varies depending on the target product to be prepared, but is not particularly limited as long as the function of the photochromic compound is not lost. Usually, it is processed at 100 to 200 ° C.

A solvent is usually used for the purpose of uniformly promoting the hydrolysis and condensation reaction, but alcohol is preferably used. Examples of the alcohol include methanol, ethanol, propanol, and butanol.

In order to accelerate the hydrolysis and condensation reaction as described above, it is a preferred embodiment to add an acidic catalyst such as hydrochloric acid, sulfuric acid, acetic acid or citric acid or a basic catalyst such as sodium hydroxide or ammonia. .. Water is a component necessary for the hydrolysis reaction, and the amount used is appropriately selected depending on the amount of the substance to be hydrolyzed, the form of the resulting silica gel and the like. A method of preliminarily hydrolyzing to an oligomer of a silicon alkoxide and a silyl group-containing photochromic compound and further hydrolyzing to complete the condensation is extremely preferable because a bulk, thin film, or particles uniformly doped with the photochromic compound can be obtained. The method via this pre-hydrolysis has the effect of suppressing only the silyl group-containing photochromic compound from being phase-separated or aggregated in the gelation process because it becomes an oligomer in which the silyl group-containing photochromic compound and the silicon alkoxide are bonded. is there.

[0020]

The photochromic hybrid silica gel produced by the present invention is not only difficult to elute the photochromic compound into an organic solvent because the organic group exhibiting photochromic properties is chemically bonded to the silica gel.
Surprisingly, the durability as a photochromic material is dramatically improved as compared with the case where a photochromic compound having no alkoxysilyl group is doped into silica gel.

The photochromic hybrid silica gel can be widely used as a photochromic material or a raw material thereof. For example, in the case of gel particles, a soluble polymer or a polymerizable monomer is dissolved in a solvent in which the gel particles are uniformly dispersed, and polymerized as necessary to coat the glasses or various coating materials, or It can be a filter or a chip for optical equipment.
It can also be used by attaching it to fibers or the like. Of course, it is also possible to directly knead the gel particles into the polymer.

Further, since this hybrid silica gel contains the photochromic compound chemically bonded as described above, even if different photochromic compounds are mixed in the same phase, they are not affected by each other and each photochromic compound is not affected. It is also useful as a recording material capable of exhibiting characteristics independently and capable of multiple recording.

[0023]

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

Example 1 To a solution prepared by dissolving 2 g of tetraethoxysilane and 0.24 g of the spirooxazine (a) described above in 20 ml of ethanol, 3.6 ml of a hydrochloric acid-ethanol aqueous solution having a pH of 3 (0.2 ml of water) was added, The mixture was stirred at 25 ° C for 5 hours. The reaction solution was added dropwise to an ammonia-ethanol aqueous solution (25% ammonia water 11.2 ml, ethanol 56 ml) with stirring. The solid formed is separated from the reaction solution by centrifugation, washed with water and ethanol, and then at 120 ° C.
Particle size 0.2-0.4μ by drying for 4 hours
m hybrid silica gel particles were obtained. Furthermore, 2 g of polymethylmethacrylate (PMMA) was added to dioxane 4
After mixing the solution dissolved in 0 ml and the dispersion liquid prepared by dispersing 0.02 g of the hybrid silica gel prepared by the above method in 2 ml of dioxane, ultrasonication was performed, and then 1 ml of this preparation liquid was poured into a petri dish to evaporate dioxane. Then, a cast film was produced.

The above PMM containing hybrid silica particles
The photochromic properties of the A film were measured and are shown in FIG. Irradiation light for coloring is mercury-Xe and lamp (3 mW /
cm ² ) was used. The irradiation time was 60 seconds. Visible light was used for fading.

Further, when the obtained hybrid silica gel particles were subjected to Soxhlet extraction with ethanol, the same photochromic properties as before the extraction were observed after the extraction. Comparative Example 1 Silica gel particles were prepared in the same manner as in Example 1 except that spirooxazine having the following structure having no alkoxysilyl group was used. However, these silica gel particles did not exhibit photochromic properties because spirooxazine was not dispersed and contained therein due to the poor affinity between spirooxazine and silica gel.

[0027]

[Chemical 3]

Example 2 20 g of tetraethoxysilane and spirooxazine (a)
To a solution of 2.4 g dissolved in 20 ml of ethanol, pH
36 ml of hydrochloric acid-ethanol aqueous solution of 3 (2 ml of water) was added, and the mixture was stirred at 25 ° C. for 5 hours. The reaction solution was allowed to stand still, and a lid with a small hole was placed on the reaction solution to gradually evaporate the solvent. It was sufficiently dried to form a xerogel and then dried at 120 ° C. for 4 hours to obtain a bulk hybrid silica gel. The silica gel was colored blue-violet when irradiated with ultraviolet rays, and exhibited photochromic properties in which it was decolorized when irradiated with visible light.

Comparative Example 2 Bulk hybrid silica gel was prepared in the same manner as in Example 2 except that the spirooxazine having no alkoxysilyl group used in Comparative Example 1 was used. This silica gel was already colored violet-blue, and when it was irradiated with ultraviolet rays, it faded and showed an inverse photochromic property.

Example 3 Tetramethoxysilane 2 g and spiropyran (e) 0.4
To a solution of 5 g dissolved in 20 ml of ethanol, 3.6 ml of a hydrochloric acid-ethanol aqueous solution having a pH of 3 (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, cooling was performed, dip coating was performed again, and this operation was repeated 10 times. Finally, heat treatment was performed at 120 ° C. for 4 hours to obtain a silica gel film. The film exhibited a photochromic property of being colored reddish purple upon irradiation with ultraviolet rays and being erased upon irradiation with visible light.

Comparative Example 3 A silica gel film was prepared in the same manner as in Example 3 except that spiropyran having the following structure having no alkoxysilyl group was used. This silica gel film had already been colored violet, and when it was irradiated with ultraviolet rays, it faded and showed an inverse photochromic property.

[0032]

[Chemical 4]

Example 4 To a solution prepared by dissolving 2.4 g of phenyltriethoxysilane and 0.24 g of spiropyran (e) in 20 ml of ethanol, 3.6 ml of a hydrochloric acid-ethanol aqueous solution having a pH of 3 (0.2 ml of water) was added. The mixture was stirred at 0 ° C for 5 hours. Aqueous ammonia solution (25% aqueous ammonia 11.2) was added to the reaction solution.
ml, water 56 ml) with stirring. The produced solid was separated from the reaction solution by centrifugation, washed with water and ethanol, and then dried at 120 ° C. for 4 hours to obtain hybrid silica gel particles.

The particles were dispersed in a PMMA film in the same manner as in Example 1, and when irradiated with a mercury-Xe lamp for 30 seconds, a reddish purple color was formed, showing photochromic characteristics. When the obtained particles were subjected to Soxhlet extraction with ethanol, the same photochromic properties as before the extraction were observed after the extraction.

Further, the above particles are molded into pellets and
When it was irradiated with an ultraviolet ray of mW / cm ² for 30 seconds, it developed a reddish purple color, and the absorbance at the peak of the absorption spectrum based on the color development was 1.04. After bleaching by irradiating with visible light and repeating erasing and decoloring by irradiating with ultraviolet ray again, it was the 56th time that the absorbance decreased to 80% of the initial value, and even at the 100th time, it was 70%. % Of the absorbance was retained and high durability was exhibited.

Comparative Example 4 3 g of phenyltriethoxysilane and 20 ml of ethanol
4 mg of the spiropyran used in Comparative Example 3 dissolved in was mixed with 4.5 ml of a hydrochloric acid aqueous solution having a pH of 3, and
The mixture was stirred at 25 ° C for 15 hours. This was added dropwise to the stirring reaction solution (25% ammonia water 11.2 ml, water 56 ml), the solid formed was separated from the reaction solution by centrifugation, washed with water, and then dried at 120 ° C. for 4 hours. By doing so, hybrid silica gel particles having photochromic properties were obtained.

When pellets were molded using these particles and color fading was repeated in the same manner as in Example 4, the initial absorbance of the color development peak was 0.95, and the absorbance decreased to 80% of this initial value. Was the 21st time.

When the above particles were Soxhlet-extracted with ethanol, the photochromic properties were not exhibited depending on the extraction time.

Example 5 2 g of phenyltrimethoxysilane and azobenzene (g)
To a solution prepared by dissolving 0.5 g in 20 ml of methanol, pH
3, hydrochloric acid-methanol aqueous solution 3.6 ml (water 0.2 m
1) 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 to obtain a silica gel film. When this film was irradiated with ultraviolet light and visible light alternately, photochromic properties due to cis-trans photoisomerization were observed.

Comparative Example 5 Phenyltriethoxysilane 2.1 g and ethanol 20
Spirooxazine 4 used in Comparative Example 1 dissolved in ml
4.5 mg of hydrochloric acid aqueous solution having a pH of 3 was added thereto, and the mixture was stirred at 25 ° C. for 15 hours. 0.8 g of tetraethoxysilane was added thereto, and the mixture was further stirred for 5 hours.
The reaction liquid (25% ammonia water 11.
2 ml, 56 ml of water), the produced solid was separated from the reaction solution by centrifugation and washed with water, and then 120
Hybrid silica gel particles having photochromic properties were obtained by drying at 4 ° C. for 4 hours. When the particles were subjected to Soxhlet extraction with ethanol, spirooxazine was eluted in ethanol and the photochromic properties of the particles were no longer observed.

Example 6 A solution of 1 g of spirooxazine (b) in 20 ml of ethanol was added to 3.6 m of an aqueous ethanol solution of hydrochloric acid having a pH of 3.
1 (0.2 ml of water) was added, and the mixture was stirred at 25 ° C for 1 hr. An ethanol solution of methyltriethoxysilane was added dropwise to the reaction solution, and the mixture was stirred at 25 ° C for 5 hours. The reaction solution was treated with an ammonia-ethanol aqueous solution (25% ammonia water 1
1.2 ml, ethanol 56 ml) was added dropwise with stirring. The produced solid was separated from the reaction solution by centrifugation, washed with water and ethanol, and then dried at 120 ° C. for 4 hours to obtain hybrid silica gel particles.

A pellet was molded using the hybrid silica gel particles, and color development and bleaching were repeated in the same manner as in Example 4. The initial absorbance was 6 even at the 100th time.
It was found to have a high durability with a value of 5% being retained.

[Brief description of drawings]

FIG. 1 is an absorption spectrum diagram when a photochromic hybrid silica gel of the present invention is irradiated with ultraviolet rays to develop a color.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08G 77/26 NUJ 8319-4J

Claims (1)

[Claims] 1. General formula (1) or (2) Si (OR ¹ ) ₄ (1) (In the formula, R ¹ represents 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 an alkyl group, and n represents an integer of 1 or 2), and an alkoxy group. A method for producing a photochromic hybrid silica gel, which comprises co-hydrolyzing and condensing a photochromic compound having a silyl group.