JP2010209288A - Water-soluble composite material containing titanium oxide, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-soluble composite material containing titanium oxide, and a method for manufacturing the same. <P>SOLUTION: A mixture of 3-aminopropyltrialkoxysilane represented by general formula: NH<SB>2</SB>(CH<SB>2</SB>)<SB>3</SB>Si(OL)<SB>3</SB>(wherein L denotes a group by which the OL group easily changes to an OH group in an acidic solution as a catalyst), and a titanium alkoxide represented by general formula: Ti(OL)<SB>4</SB>(wherein L denotes a group by which the OL group easily changes to an OH group in an acidic solution as a catalyst) is reacted in an acidic alcohol solution. Then, the mixture is polymerization reacted in water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-soluble composite material containing titanium oxide and a method for producing the same.

Since titanium oxide (TiO ₂ ) can be used in a wide range of fields such as a photocatalyst (see Non-Patent Document 1), a highly refractive material (see Non-Patent Document 2), and an ultraviolet absorbing material (see Non-Patent Document 3), attention is paid. It is a material that has been. In these applications, these materials are used by being dispersed at a level of several nanometers to several tens of nanomails. For example, since the photocatalytic efficiency of TiO ₂ depends on its surface area, a more finely dispersed TiO ₂ having the same crystal structure and weight has better catalytic efficiency. In addition, many studies have been made to disperse TiO _{2 in} organic polymers for the purpose of improving the refractive index of transparent plastics (organic polymers), but particles that are sufficiently smaller than the wavelength of visible light are not aggregated. Dispersion is important for maintaining transparency. Furthermore, even when it is mixed with cosmetics or the like for the purpose of cutting off ultraviolet rays, it is desired to finely disperse it to a level at which visible light is not scattered so as not to affect the color. From the above, it is desired to create a material based on TiO ₂ that is dispersed to the nano level and does not aggregate again.

So far, synthesis of TiO ₂ nanocomposite particles grafted with organic polymer chains has been performed by carrying out a polymerization reaction from the surface of TiO ₂ particles (see Non-Patent Document 4). This is because the solubility of the organic polymer contributes to the dispersibility of the TiO ₂ nanocomposite. It has also been reported that TiO ₂ particles having nano-dispersibility can be obtained by modifying the surface of TiO ₂ particles with a silane coupling agent having an amino group (see Non-Patent Document 5).

On the other hand, it is known that sheet-like TiO ₂ having a thickness of 1 nanometer can be obtained by peeling off the layered titanate, which is a material that is well dispersed in an aqueous solution containing ammonium ions (non-patent document). Reference 6).

Furthermore, titania sol, which is a precursor of TiO ₂ particles, films, coatings, and the like, can also be said to be dispersible TiO ₂ , but this causes the sol-gel reaction to proceed by evaporating the solvent, and once TiO ₂ is precipitated, it again It is difficult to disperse. Therefore, for the purpose of synthesizing redispersible TiO ₂ by sol-gel reaction, TiO ₂ base materials containing silica (SiO ₂ ) and silane coupling agent (RMe ₂ SiO _0.5 ) components have been created so far. (See Non-Patent Document 7). In addition, the material obtained by the sol-gel reaction of titanium alkoxide in a non-aqueous solvent (mixed solvent of butanol and toluene) can be dissolved again in the mixed solvent, and nano-dispersible TiO ₂ It can be said that it is a base material (see Non-Patent Document 8).

As described above, many studies on the synthesis of TiO ₂ exhibiting nano-dispersibility have been conducted.

However, TiO ₂ cannot be dissolved in water by conventional techniques.

JP 2005-120333 A JP 2006-045392 A

Y. Amao, "Photoenergy conversion system based on the photosynthesis dyes conjugated nanoparticle" Current Nanoscience, Vol: 4, page: 45-52, (2008) JG.Liu and 5 others, "Optically transparent sulfur-containing polyimide-TiO2 nanocomposite films with high refractive index and negative pattern formation from poly (amic acid) -TiO2 nanocomposite film", Chemistry of Materials, Vol: 20, Page: 273- 281, (2008) M.Zayat and 2 others, "Preventing UV-light damage of light sensitive materials using a highly protective UV-absorbing coating", Chemical Society Reviews, Vol: 36, page: 1270-1281, (2007) M. Kobayashi and 3 others, "Precise surface structure control of inorganic solid and metal oxide nanoparticles through surface-initiated radical polymerization", Science and Technology of Advanced Materials, Vol: 7, Page: 617-628, (2006) A. Andrzejewska and 2 others, “Adsorption of organic dyes on the aminosilane modified TiO2 surface”, Dyes and Pigments, Vol: 62, page: 121-130, (2004) T. Sasaki and 1 other, “Osmotic swelling to exfoliation. Exceptionally high degrees of hydration of a layered titanate”, Journal of the American Chemical Society, Vol: 120, page: 4682-4689, (1998) T. Suzuki and 3 others, “Preparation and properties of inorganic-organic composite-materials containing R3SiO1 / 2, SiO2, and TiO2 units”, Chemistry of Materials, Vol: 6, page: 692-696, (1994) E.M.Mohamed and 4 others, “High-quality growth of TiO2 thin film from its precursor solution by new sol-gel method”, Electrochemistry, Vol: 72, page: 455-457 (2004) Y.Kaneko and 5 others, “Hexagonal-structured polysiloxane material prepared by sol-gel reaction of aminoalkyltrialkoxysilane without using surfactants”, Chemistry of Materials, VoL: 16, page: 3417-3423, (2004) Y.Kaneko and 3 others, “Synthesis of rodlike polysiloxane with hexagonal phase by sol-gel reaction of organotrialkoxysilane monomer containing two amino groups”, Polymer, VoL: 46, page: 1828-1833, (2005) Y.Kaneko and 1 other, “Sol-gel synthesis of rodlike polysilsesquioxanes forming regular higher-ordered nanostructure”, Zeitschrift fur Kristallographie, Vol: 222, page: 656-662 (2007) Y.Kaneko and 3 others, “Synthesis of water-soluble silicon oxide material by sol-gel reaction in tetraalkoxysilane-aminoalkyltrialkoxysilane binary system”, Journal of Materials Research, Vol: 20, page: 2199-2204 (2005)

  An object of this invention is to provide the water-soluble composite material containing a titanium oxide, and its manufacturing method.

  In order to solve the above problems, the inventor of the present application focused on a method for producing a rod-shaped polysiloxane having an ammonium cation (Patent Document 1, Patent Document 2, Non-Patent Document 9, Non-Patent Document 10, Non-Patent Document 11). ). This polysiloxane can be synthesized by an acid-catalyzed sol-gel reaction of an amino group-containing trialkoxysilane. Usually, when such a polyfunctional alkoxysilane is used to carry out a sol-gel reaction, a polysiloxane having a network structure in which the reaction grows in a three-dimensional direction is obtained. However, this material prevents the reaction from spreading in a three-dimensional direction by the action of a salt (ion complex) consisting of the amino group of the raw material and the acid of the catalyst, and as a result, rod-shaped polysiloxane having a diameter of about 1 to 2 nm is formed. It is formed. This material is an inorganic material excellent in dispersibility and solubility that is laminated with a regular nano-order structure (hexagonal phase) in a solid state and becomes a transparent aqueous solution when water is added.

  Furthermore, the inventor of the present application also paid attention to a method for producing a water-soluble silicon oxide material having an ammonium cation on the surface (Patent Document 1, Non-Patent Document 12). This material is obtained by a sol-gel reaction of a mixture of tetraalkoxysilane, which is a raw material of silicon oxide (silica), and the above-mentioned amino group-containing trialkoxysilane, and can be repeatedly precipitated and dissolved. It is a material showing solubility. This is also considered to be water-soluble because the action of an ion complex comprising an amino group-containing trialkoxysilane and a catalyst acid can suppress the spread of the reaction in the three-dimensional direction and control the particle size.

  It is an element required for a water-soluble material that the particle diameter is sufficiently smaller than the wavelength of visible light and the surface of the particle has a substituent that is compatible with water. Therefore, the inventor of the present application performs reaction by coexisting an amino group-containing trialkoxysilane and a catalyst acid with respect to titanium alkoxide, which is a raw material of titanium oxide, based on the method for synthesizing the water-soluble material described above. It came to the idea that a water-soluble composite material with controlled particle size could be synthesized. Specifically, a mixture of titanium tetraalkoxide and 3-aminopropyltrialkoxysilane may be heated in an acid solution and reacted to synthesize a water-soluble composite material with controlled particle size. I came up with an idea.

  And as a result of performing sol-gel reaction under acidic conditions in the preparation ratio of titanium tetraalkoxide and 3-aminopropyl trialkoxysilane in the range of 0: 100 to 50:50, titanium oxide and silicon showing water solubility It has been found that a composite material (hereinafter sometimes referred to as a water-soluble titanium oxide / silicon composite material) can be synthesized. Furthermore, the inventors have conceived the following aspects of the invention.

In the water-soluble composite material according to the present invention, the repeating unit has a general formula: Z ⁻ .NH ₃ ⁺ (CH ₂ ) ₃ SiO _1.5 (wherein Z ⁻ is a halogen element anion such as a chloride ion, and nitric acid) And a repeating unit is composed of a skeleton having a general formula; a composition represented by TiO ₂ .

  Since such a water-soluble composite material contains titanium oxide and has an ammonium cation, it exhibits solubility such that a highly transparent solution can be obtained. Moreover, the re-solubility which can perform precipitation and melt | dissolution repeatedly is also shown. Furthermore, stability in a reactive solvent such as water is also shown.

An example of the structure in the case where Z in the general formula: Z ⁻ .NH ₃ ⁺ (CH ₂ ) ₃ SiO _1.5 is a chloride ion is shown in (Chemical Formula 1). However, n represents a polymerization degree.

The method for producing a water-soluble composite material according to the present invention has a general formula: NH ₂ (CH ₂ ) ₃ Si (OL) ₃ (wherein L is easily changed from an OL group to an OH group in an acidic solution serving as a catalyst). 3-aminopropyltrialkoxysilane represented by the general formula; Ti (OL) ₄ (wherein L represents an OH group easily converted into an OH group in an acidic solution serving as a catalyst). And a step of reacting a mixture with a titanium alkoxide represented by (1) in an acidic alcohol solution, and then a step of polymerizing the mixture in water.

  According to such a method, said water-soluble composite material can be manufactured by a simple process.

  According to the present invention, high transparency can be obtained when an aqueous solution is used. For this reason, ultraviolet absorption derived from titanium oxide can be used effectively.

It is a figure which shows the synthesis | combining method of the water-soluble titanium oxide / silicon composite material by sol-gel reaction. It is a figure which shows IR spectrum of a product. It is a figure which shows the UV-Vis spectrum of the aqueous solution of a product. It is a figure which shows the state of (a) 1.0 w / v% aqueous solution of a product, and (b) solid state. It is a figure which shows the particle size distribution by the dynamic light scattering (DLS) measurement of 0.5 w / v% aqueous solution (25 degreeC) of a product: (a) weight average distribution, (b) number average distribution. FIG. 6 shows a UV-Vis spectrum of the product film.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, these examples are shown as an aid for easily understanding the present invention, and are not intended to limit the present invention in any way.

Here, an experiment actually performed by the present inventor will be described. A reaction scheme for the synthesis of water-soluble titanium oxide / silicon composite is shown in FIG. To 0.897 g (= 5 mmol) of 3-aminopropyltrimethoxysilane (APTMOS), 12.5 mL (= 6.25 mmol) of 0.5 mol / L hydrochloric acid methanol solution was added to prepare a uniform solution. Tetraisopropoxide (Ti (isoPrO) ₄ ) is added to a solution of 1.421 g (= 5 mmol) in isopropyl alcohol (37.5 mL), stirred at room temperature for 2 hours, and then heated at 50 to 60 ° C. in an open system. The solvent was evaporated. Subsequently, 50 mL of water was added to the obtained powdery product and heated at 60 ° C. to 70 ° C. in an open system to evaporate the water, thereby obtaining a glassy product. This product was heated at 100 ° C. for 30 minutes to allow the reaction to proceed sufficiently, and then 100 mL of water was added to dissolve it, which was lyophilized to obtain a glassy white product (1.217 g). The structure of the main chain skeleton of the product was examined by infrared (IR) spectrum and energy dispersive X-ray (EDX) measurement.

The IR spectrum of the product obtained by the above reaction is shown in FIG. In addition to absorption peaks derived from —NH ₃ ⁺ groups (1612 cm ⁻¹ and 1497 cm ⁻¹ ), absorption peaks derived from Si—O—Si bonds (1119 cm ⁻¹ ), absorption peaks derived from Ti—O—Si bonds (900 cm) ⁻¹ ), and an absorption peak (697 cm ⁻¹ ) derived from Ti—O—Ti bond were observed. This suggested that a titanium oxide / silicon composite material was formed.

  Moreover, from the result of EDX measurement of the product obtained by the above reaction, it was confirmed that the ratio of the number of atoms of Ti and Si was 1: 1, and the composition ratio was almost the same as the raw material charge ratio. Was suggested.

  In order to evaluate the transparency of the aqueous solution at various concentrations of the product, UV-Vis spectroscopic measurements were performed. As a result, at a concentration of 1.0 w / v% or less, a transmittance of 96% or more was observed with 500 nm visible light, suggesting that a very transparent aqueous solution was obtained (FIG. 3). It was confirmed from a photograph of a 1.0 w / v% aqueous solution of the product that the solution was transparent (FIG. 4 (a)).

  On the other hand, the solid product was regenerated by freeze-drying the aqueous solution (FIG. 4B). This indicates that the reason why the product was dissolved in water was not due to the decomposition of Ti—O bonds or Si—O bonds. The dissolution of the product in water and the precipitation of the solid product by lyophilization could be repeated, suggesting that the product is a re-dissolvable material.

  On the other hand, the aqueous solution of the product has a property of blocking ultraviolet light, and has an ultraviolet light of 360 nm or less in a 10 w / v% aqueous solution, 340 nm or less in a 1.0 w / v% aqueous solution, and 300 nm or less in a 0.1 w / v% aqueous solution. It was clarified that most can be blocked (FIG. 3).

  In order to measure the particle size of the product, a 0.5 w / v% aqueous solution was prepared and DLS measurement was performed at 25 ° C. The weight and number average particle size calculated by the cumulant method were found to be 9.3 ± 2.2 and 8.2 ± 1.6 nm, respectively (FIG. 5), and the product had an average particle size of 10 nm. The following were confirmed to be nanoparticles that dissolve well in water.

An aqueous solution of the above product was applied to a quartz plate and naturally dried at room temperature to form a film. Here, UV-Vis spectrum measurement was performed using three types of films (1 g / cm ² , 5 g / cm ^2, and 10 mg / cm ² ) having different thicknesses. As a result, all the films showed a transmittance of 98% with respect to visible light of 500 nm (FIG. 6), suggesting that they were very transparent films. Moreover, the photograph of the film of the product prepared at 10 mg / cm < ² > is shown in FIG. 6, It has confirmed that it was a transparent film from now on.

These films have the property of blocking ultraviolet light, 340 nm or less for films prepared at 10 mg / cm ² , 320 nm or less for films prepared at 5 mg / cm ² , and 260 nm or less for films prepared at 1 mg / cm ² . Most of the ultraviolet light is blocked (FIG. 6). Due to these properties, it can be expected to be used as a coating agent for UV protection.

  Thus, the water-soluble composite material produced by a series of these treatments exhibits high transparency when made into an aqueous solution. For this reason, ultraviolet absorption derived from titanium oxide can be used effectively. For example, it can be used for cosmetics utilizing ultraviolet absorption. It can also be used to create a hybrid material that imparts a high refractive index property of titanium oxide to transparent plastic. Furthermore, such a water-soluble composite material also exhibits re-solubility that allows repeated precipitation and dissolution, and stability in a reactive solvent such as water.

  The present invention has been derived and clarified as a result of accumulating many experiments other than the examples shown above. The invention is not limited to the disclosed embodiments. Through many experiments, the important point in the present invention is that the material obtained by adjusting the amount of raw materials charged under acidic conditions in the sol-gel method for synthesizing the water-soluble titanium oxide / silicon composite material This means that it is possible to easily control the particle size and surface morphology of the material. For example, an appropriate water-soluble composite material can be obtained when (amount of titanium tetraalkoxide) / (amount of 3-aminopropyltrialkoxysilane) ≦ 1 under acidic conditions.

  According to the present invention, a water-soluble composite material of titanium oxide and silicon capable of obtaining a transparent and stable aqueous solution that has not existed before is obtained, and this water-soluble composite material is obtained in both an aqueous solution and a film. Can be used. In addition to the property of absorbing ultraviolet light, it has a reactive amino group on its surface, so it can be introduced into functional molecules and hybridized with organic polymers, and will be used in various fields in the future. There is expected.

Claims (4)

A composition in which the repeating unit is represented by the general formula: Z ⁻ .NH ₃ ⁺ (CH ₂ ) ₃ SiO _1.5 (wherein Z ⁻ represents an anion);
The repeating unit is represented by the general formula: TiO ₂ ;
A water-soluble composite material comprising a skeleton having   The water-soluble composite material according to claim 1, wherein the average particle size is 10 nanometers or less. 3-aminopropyltri-- represented by the general formula: NH ₂ (CH ₂ ) ₃ Si (OL) ₃ (wherein L represents a group in which the OL group can be changed to an OH group in an acidic solution serving as a catalyst). A mixture of an alkoxysilane and a titanium alkoxide represented by the general formula; Ti (OL) ₄ (wherein L represents a group capable of changing an OL group to an OH group in an acidic solution serving as a catalyst) Reacting with an alcohol solution;
Next, a step of polymerizing the mixture in water;
A method for producing a water-soluble composite material, comprising:   The method for producing a water-soluble composite material according to claim 3, wherein the polymerization reaction is a sol-gel reaction.

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