KR20230082784A - Method for Preparing Titania Nanosol, and Method for Preparing Titania Nanofibers Using Titania Nanosol Prepared Thereby - Google Patents

Abstract

The present invention relates to a technology for producing highly active photolytic titanium dioxide nanofibers capable of exhibiting excellent photolytic properties as a photocatalyst, and more specifically, to a method of using titanium dioxide nanosol in which titanium dioxide nanoparticles are dispersed in the production of titanium dioxide nanofibers, and a method for preferably producing the titanium dioxide nanosol. The method for producing titanium dioxide nanosol according to the present invention comprises: a first step of adding water and titanium tetrachloride (TiCl_4) to the reactor and heating while stirring; a second step of adding and stirring hydrochloric acid (HCl) when the temperature reaches 50-60℃; and a third step of natural cooling and stirring, to produce titanium dioxide nanosol with a titanium dioxide solid content of 12-16 wt%. The method for producing titanium dioxide nanofibers according to the present invention is characterized in that it is produced by electrospinning and heat treating a precursor solution composition composed to comprise: 35-40 wt% of titanium dioxide nanosol with a titanium dioxide solid content of 12-16 wt%; ethanol 55-60 wt%; 3-4.5 wt% of polymer resin; and 1-1.5 wt% of silane coupling agent.

Description

Method for preparing titanium dioxide nanosol and method for producing photolytically active titanium dioxide nanofibers using nazosol prepared by the method {Method for Preparing Titania Nanosol, and Method for Preparing Titania Nanofibers Using Titania Nanosol Prepared Thereby}

The present invention relates to a manufacturing technology of photolytically active titanium dioxide nanofibers capable of exhibiting excellent photolysis characteristics as a photocatalyst, and more particularly, to a method of using titanium dioxide nanosols in which titanium dioxide nanoparticles are dispersed in the production of titanium dioxide nanofibers. and a method for preferably preparing the titanium dioxide nanosol.

Nanotechnology is a microscopic technology that goes beyond micro, which means one-millionth. Since nanomaterials can realize the best performance while minimizing size and energy consumption, they are advantageously applied as materials for electronic devices requiring portability and convenience.

Electrospinning is one of the methods for manufacturing nanomaterials. Electrospinning is a method of making continuous phase nanofibers using an electric field. Electrospinning proceeds by introducing a polymer solution at a constant rate through a pump and discharging it through a nozzle. The polymer solution discharged from the tip of the nozzle forms a hemispherical shape due to surface tension, and when a high voltage is applied to the nozzle, the liquid polymer droplets are elongated into a conical funnel shape. When the charge continues to accumulate in the polymer solution of the nozzle to which the electrode is connected, the surface tension of the polymer solution is overcome by the mutual repulsive force, and the funnel shape at the tip of the nozzle is radially stretched by the jet, and the fibers are collected by the collector plate. During the electrospinning process, drawing and volatilization of the solvent are accompanied before the liquid jet reaches the collector plate, resulting in randomly arranged fine fibers. Metal oxide nanofibers include metal precursors or metal oxide precursors in polymers, spin them, and heat-treat them to prepare desired metal phases and metal oxides (Journal of the Institute of Electrical and Electronic Materials, Vol. 31, No. 6, etc.).

Metal oxide nanofibers prepared through electrospinning typically include titanium dioxide (TiO ₂ ) nanofibers. Titanium dioxide nanofibers are physically and chemically stable and have heat resistance, biocompatibility, photocatalytic properties, etc., and are applied in many fields. In particular, they are widely used in air pollution sensors and pollutant removal filters using photocatalytic properties.

On the other hand, there is Patent No. 10-2183306 in relation to the manufacturing technology of titanium dioxide nanofibers. Patent No. 10-2183306 is a technology that makes it possible to control the diameter of spinning fibers by providing Na+ metal ions in the manufacturing process of titanium dioxide nanofibers to further facilitate the flow of electricity during the electrospinning process.

However, in the manufacturing technology of titanium dioxide nanofibers through conventional electrospinning, including Patent No. 10-2183306, it is essential to secure the crystallinity of titanium dioxide through heat treatment of the spun nanofibers in order to secure the photocatalytic performance of titanium dioxide. requires a maintenance treatment of 3 hours or more at a temperature of 400 ° C or higher. In addition, the precursor solution used for electrospinning must be prepared with a residual amount of titanium dioxide of 3% or less in order to form nano-sized titanium dioxide particles. It is manufactured at a level of 40% or less by weight of If the residual amount of titanium dioxide is increased or excessive electrospinning conditions are applied to improve the manufacturing yield, the diameter of the produced spun fiber increases, making it difficult to secure the photolysis characteristics of the nanofiber.

KR 10-2183306 B1

The present invention was developed to improve the conventional manufacturing technology of titanium dioxide nanofibers, and there is a technical problem in providing a manufacturing technology of titanium dioxide nanofibers capable of simplifying the process through a decrease in heat treatment temperature.

In addition, the present invention is to provide a preferred method for preparing titanium dioxide nanosol containing up to 16% by weight of titanium dioxide solids having crystallinity of photolysis performance while being able to be used as a main material of a precursor solution for the production of titanium dioxide nanofibers. do.

In addition, the present invention is to provide a manufacturing technology of photolytically highly active titanium dioxide nanofibers capable of exhibiting excellent photolytic properties as a photocatalyst.

In order to solve the above technical problem, the present invention, water, titanium tetrachloride (Titanium tetrachloride, TiCl ₄ ) in the reactor a first step of heating while stirring; A second step of stirring by adding hydrochloric acid (HCl) when the temperature reaches 50 to 60 ° C; A third step of natural cooling and stirring; provides a method for preparing titanium dioxide nano-sol, characterized in that the titanium dioxide nano-sol having a titanium dioxide solid content of 12 to 16% by weight is prepared.

In addition, the present invention titanium dioxide solid content of 12 to 16% by weight titanium dioxide nano sol 35 to 40% by weight; 55 to 60% by weight of ethanol; 3 to 4.5% by weight of polymer resin; It provides a precursor solution composition for preparing titanium dioxide nanofibers, characterized in that the composition includes; 1 to 1.5% by weight of a silane coupling agent. Here, polyvinylpyrrolidone (PVP) may be preferably used as the polymer resin, and methacryloxypropyl triethoxysilane may be preferably used as the silane coupling agent.

In addition, the present invention electrospun a precursor solution composition containing titanium dioxide nanosol having a titanium dioxide solid content of 12 to 16% by weight at a rate of 1.2 to 1.5 ml / hr under the conditions of a voltage of 20 kV and a distance of 20 cm between the nozzle and the ground plate. It provides a method for producing photolytically active titanium dioxide nanofibers, characterized in that they are produced by heat treatment at 180 to 210 ° C. for 4 hr or more.

According to the present invention, the following effects can be expected.

First, in the production of titanium dioxide nanofibers, since titanium dioxide nanoparticles in a sol state in which titanium dioxide nanoparticles are evenly dispersed in a water system are used, it is necessary to decompose only the polymer resin without a separate high-temperature heat treatment process to secure titanium dioxide crystallinity. Titanium dioxide nanofibers of uniform quality, in which titanium dioxide nanoparticles are evenly dispersed, can be produced only by a heat treatment and drying process at a relatively low temperature. Accordingly, it is possible to easily manufacture titanium dioxide nanofibers while simplifying the manufacturing process.

Second, in the production of titanium dioxide nano-sols, nano-sols containing 12 to 16% by weight of titanium dioxide solids having crystallinity of photolysis performance can be prepared. When titanium dioxide nanofibers are prepared using the thus prepared titanium dioxide nanosol, it is possible to manufacture titanium dioxide nanofibers with improved photolysis characteristics as a photocatalyst and high activity. Thus, the titanium dioxide nanofibers prepared according to the present invention can be advantageously used as photocatalysts in air pollution sensors, pollutant removal filters, and the like.

1 is a result of [Test Example 1], a graph of XRD analysis results for titanium dioxide nanofibers and a SEM measurement photograph.
2 is a photograph of a model test specimen for evaluation of photolysis characteristics of titanium dioxide nanofibers as a result of [Test Example 2].

The present invention relates to a technology for producing photocatalytic titanium dioxide nanofibers through electrospinning, a method for producing titanium dioxide nanofibers using a titanium dioxide nanosol in which titanium dioxide nanoparticles are dispersed, and a preferred method of the titanium dioxide nanosol Propose a manufacturing method.

1. Manufacturing method of titanium dioxide nano sol

The present invention uses an aqueous titanium dioxide nano-sol in the composition of an electrospinning precursor solution for preparing titanium dioxide nanofibers, and proposes a preferred method for preparing titanium dioxide nano-sols containing up to 16% titanium dioxide solids. Titanium dioxide nano sol manufacturing method according to the present invention, a first step of heating while stirring while water, titanium tetrachloride (Titanium tetrachloride, TiCl ₄ ) is added to the reactor; A second step of stirring by adding hydrochloric acid (HCl) when the temperature reaches 50 to 60 ° C; It is characterized in that it comprises a; third step of stirring by natural cooling.

The first step may be performed while maintaining stirring at 2000 rpm or more after adding 20 to 30 parts by weight of titanium tetrachloride to 100 parts by weight of water. Here, the content range of titanium tetrachloride is to secure an appropriate solid content of titanium dioxide. If it is less than 20 parts by weight, the solid content necessary for forming titanium dioxide is insufficient, and if it exceeds 30 parts by weight, titanium dioxide particles are partially undispersed due to excessive mixing. A separate filtration process may be required due to the formation of precipitates.

The second step is the process of adding hydrochloric acid serving as a peptizing agent for the dispersion of the nano-sol. When the temperature reaches 50 to 60 ° C, 0.5 to 1.0 parts by weight of 0.1 to 0.3 M hydrochloric acid is added and heated at 2000 rpm or more for 15 to 30 minutes. It can be carried out while maintaining stirring. Hydrochloric acid is added at an elevated temperature of 50 to 60 ° C. If the temperature is lower than 50 ° C, titanium dioxide particles are not dispersed in nano-size even when hydrochloric acid is added, making it impossible to manufacture nanosols. If the temperature exceeds 60 ° C, hydrochloric acid is mixed. Carbonization (blackening of color) occurs due to heat, and as a result, titanium dioxide nanoparticles partially aggregate and precipitate with each other, making it difficult to manufacture nanosols. In the second step, the concentration and amount of hydrochloric acid, stirring time, etc. become conditions for smooth peptization (dispersion) without being carbonized when hydrochloric acid is added.

The third step can be carried out while maintaining stirring for 10 to 15 hours by natural cooling. When titanium tetrachloride is added to water, it reacts with water to exist as particles of hundreds of μm. Then, when hydrochloric acid is added, titanium dioxide particles are dispersed and crystals are formed. this becomes possible In particular, if the stirring time is less than 10 hours, it is difficult to sufficiently disperse the nanoparticles, and if the stirring time exceeds 15 hours, since the nanoparticle dispersion becomes stabilized, no further process time is required.

When prepared by the above process, the titanium dioxide nanoparticles are evenly dispersed to produce a titanium dioxide nanosol containing 12 to 16% by weight of titanium dioxide solids. When the thus-prepared titanium dioxide nano-sol is used in a precursor solution and electrospun, nanofibers having a high titanium dioxide content are produced and exhibit improved photolysis characteristics as a photocatalyst.

2. Manufacturing method of titanium dioxide nanofibers

The present invention proposes a method for producing titanium dioxide nanofibers by preparing a precursor solution using a titanium dioxide nanosol prepared to contain 12 to 16% by weight of titanium dioxide solid content, electrospinning the precursor solution, and then heat-treating the precursor solution. In particular, the precursor solution in the present invention is 35 to 40% by weight of titanium dioxide nanosol prepared to contain 12 to 16% by weight of titanium dioxide solids; 55 to 60% by weight of ethanol; 3 to 4.5% by weight of polymer resin; 1 to 1.5% by weight of a silane coupling agent;

In the precursor solution, the titanium dioxide nanosol becomes the basic material to provide the titanium dioxide nanoparticles. Since titanium dioxide nano-sol is in a sol state in which titanium dioxide nanoparticles are evenly dispersed in an aqueous system, titanium dioxide nanoparticles are uniformly dispersed only through a heat treatment and drying process to decompose polymer resin without a separate high-temperature heat treatment process to secure titanium dioxide crystallinity. It makes it possible to produce dispersed titanium dioxide nanofibers of uniform quality. In addition, since the titanium dioxide nanosol contains 12 to 16% by weight of titanium dioxide solids having crystallinity of photolysis performance, it is possible to manufacture titanium dioxide nanofibers with improved photolysis characteristics as a photocatalyst. Such titanium dioxide nanosols are used in an amount of 35 to 40% by weight in the precursor solution. If it is less than 35% by weight, the content of titanium dioxide particles that must be present in the fiber phase during the manufacture of titanium dioxide nanofibers is too low, so that the fiber phase is easily broken during heat treatment, and furthermore, the photolysis performance as a photocatalyst remains at a low level even after heat treatment. If it exceeds 40% by weight, the content of the polymer resin compared to the titanium dioxide particles is reduced, and the shape retention characteristics of the spun fibers are deteriorated during the electrospinning process, making it difficult to manufacture titanium dioxide nanofibers.

Ethanol (etOH) in the precursor solution becomes an effective solvent for dispersing the polymer resin dissolved when mixed with the titanium dioxide nanosol, and at the same time, it is a solvent that enables nano-sized electrospinning by lowering the surface tension of the precursor solution during the electrospinning process. . In the precursor solution, 55 to 60% by weight of ethanol is used. If it is less than 55% by weight, the solid content of the precursor solution increases, making nano-sized spinning difficult during the electrospinning process. If it exceeds 60% by weight, the solid content of the precursor solution is excessive. It may be difficult to maintain the shape of the spun fiber during the electrospinning process.

In the precursor solution, the polymer resin becomes a material for maintaining the shape of the spun fiber, and polyvinylpyrrolidone (PVP) can be preferably used in consideration of economic feasibility and compatibility. The polymer resin is used in an amount of 3 to 4.5% by weight in the precursor solution. If it is less than 3% by weight, it is difficult to maintain the fiber shape during electrospinning, and if it exceeds 4.5% by weight, it is difficult to form a fiber shape such as aggregation of fibers.

When mixed with a polymer resin such as PVP, the silane coupling agent in the precursor solution facilitates electrospinning by lengthening the bonded repeating unit of the polymer resin, and also lowers the viscosity by the water-based titanium dioxide nano sol, which is effective in the electrospinning process. It becomes a material that improves the problem that the fiber shape can be difficult. As the silane coupling agent, methacryloxypropyl triethoxysilane can be preferably used. The silane coupling agent is used in an amount of 1 to 1.5% by weight in the precursor solution. If the amount is less than 1% by weight, the improvement effect due to the incorporation of the silane coupling agent is insufficient, and if it exceeds 1.5% by weight, the economic efficiency is poor.

After electrospinning the precursor solution as described above, heat treatment is performed to remove the polymer resin, and titanium dioxide nanofibers can be produced. At this time, electrospinning can be performed while spinning the bulb solution at a rate of 1.2 to 1.5 ml / hr under the condition of a voltage of 20 kV and a distance of 20 cm between the nozzle and the ground plate, and the heat treatment can be performed at 180 to 210 ° C. for 4 hr or more. . As a result, the polymer resin is effectively removed, while titanium dioxide has crystallinity, so that titanium dioxide nanofibers exhibit excellent photolysis characteristics as a photocatalyst.

Hereinafter, the present invention will be described in detail based on preparation examples and test examples. However, the preparation examples and test examples below are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Preparation Example 1] Preparation of titanium dioxide nano sol

100 parts by weight of water, 25 parts by weight of TiCl ₄ (density 1.73g/cc, colorless, purity >99%), and 0.8 parts by weight of HCl (0.2M) were prepared as raw materials for preparing titanium dioxide nanosol. After adding water to a reactor capable of stirring and heating, TiCl ₄ is added to maintain stirring at 2000 to 3000 rpm, and then, when the internal temperature of the reactor reaches 50 to 60 ° C by heating the reactor, HCl is added and stirred for about 20 minutes. While maintaining, and finally, after natural cooling, stirring was maintained for 12 hr or more. Thus, titanium dioxide nano sol was prepared. The prepared titanium dioxide nano sol was dried at 200 ° C. for 12 hr or more, and as a result of confirming the solid content, it was confirmed to be 15.3% by weight.

[Preparation Example 2] Preparation of electrospun nanofibers

1. Composition of the precursor solution

A precursor solution was prepared with the composition shown in [Table 1] below, including the titanium dioxide nano-sol prepared in [Preparation Example 1].

Prosolution composition (% by weight) division Example note Titanium dioxide nanosol 38 [Preparation Example 1] Solid content 15.3%, pH 3.3 ethanol 57 99.5% pure ethanol, density 0.79g/cc polyvinylpyrrolidone
(K-30) 3.7 White powder, pH 5-8 (10 g/L solution),
Specific gravity 1.05, molecular weight (MW) 1~1.7x10 ⁶ Silane coupling agent (methacryloxypropyl triethoxysilane) 1.3 Specific gravity 0.99, refractive index 1.427 Sum 100 -

2. Electrospinning

Electrospinning was performed under conditions of a voltage of 20 kV and a distance of 20 cm between the nozzle and the ground plate using the precursor solution prepared as shown in [Table 1] above, and the electrospinning treatment was performed at a rate of 1.2 to 1.5 ml/hr.

3. Heat treatment of spun fibers

PVP was removed by heat-treating the spun fibers at a temperature of 180 to 210 ° C. for 4 hr or more, thereby preparing titanium dioxide nanofibers having titanium dioxide nanoparticles.

[Test Example 1] Analysis of titanium dioxide nanofibers

The weight before and after heat treatment was confirmed for the titanium dioxide nanofibers prepared in [Preparation Example 2], and as a result, the weight residual rate after heat treatment was confirmed to be 15.5%. In addition, crystallinity and fiber diameter characteristics were evaluated for the titanium dioxide nanofibers after heat treatment, and the results were shown in FIG. 1. As shown in FIG. 1, the titanium dioxide nanofibers finally prepared after heat treatment were confirmed to have anatase crystals having excellent properties as a photocatalyst as a result of XRD analysis, and also as a result of SEM measurement, it was confirmed that the diameter of the spinning fibers was less than 200 nm. .

[Test Example 2] Photolysis characteristics of titanium dioxide nanofibers

The photolysis characteristics of the titanium dioxide nanofibers finally prepared in [Preparation Example 2] were compared with existing titanium dioxide nanofibers (manufactured according to Patent No. 10-2183306). To evaluate the photodegradation characteristics, panel model specimens were produced using lightweight aggregates. In particular, the model specimens were prepared by incorporating 2% by weight of titanium dioxide nanofibers compared to the volume of the model specimen (specific gravity 1). On the dried surface of the prepared model test body, a red pigment solution prepared by dissolving acidred 44 organic dye at 0.02M was applied to only 1/2 of the model test body, and then dried indoors for 1 day, and after exposure of the dried model test body under visible light Decomposition of the red organic dye was confirmed by color change and evaluated by photolysis characteristics.

The result of confirming the color change is shown in FIG. 2 . As can be seen, at the lapse of 5 hours of visible light irradiation, it was confirmed that the red dye was completely decomposed on the surface of the model specimen prepared by mixing the titanium dioxide nanofibers of [Production Example 2], but the surface of the model specimen manufactured by mixing the existing titanium dioxide nanofibers It was confirmed that some red dye remained. Through these results, it can be said that the titanium dioxide nanofibers prepared according to the present invention have excellent photolysis characteristics.

Claims (6)

A first step of heating while stirring by adding water and titanium tetrachloride (TiCl ₄ ) to the reactor;
A second step of stirring by adding hydrochloric acid (HCl) when the temperature reaches 50 to 60 ° C;
A third step of stirring by natural cooling;
A method for producing a titanium dioxide nano-sol, characterized in that the titanium dioxide nano-sol having a titanium dioxide solid content of 12 to 16% by weight is prepared by including a. In paragraph 1,
The first step is carried out while maintaining stirring at 2000 rpm or more after adding 20 to 30 parts by weight of titanium tetrachloride to 100 parts by weight of water,
In the second step, when the temperature reaches 50 to 60 ° C, 0.5 to 1.0 parts by weight of 0.1 to 0.3 M hydrochloric acid is added and carried out while maintaining stirring at 2000 rpm or more for 15 to 30 minutes,
The third step is a method for producing titanium dioxide nano sol, characterized in that carried out while maintaining stirring for 10 to 15 hours by natural cooling. 35 to 40% by weight of the titanium dioxide nanosol prepared according to claim 1 or 3;
55 to 60% by weight of ethanol;
3 to 4.5% by weight of polymer resin;
1 to 1.5% by weight of a silane coupling agent;
A precursor solution composition for producing titanium dioxide nanofibers, characterized in that the composition comprises a. In paragraph 3,
The polymer resin is polyvinylpyrrolidone (PVP),
The silane coupling agent is a precursor solution composition for producing titanium dioxide nanofibers, characterized in that methacryloxypropyl triethoxysilane. A method for producing photolytically active titanium dioxide nanofibers, characterized in that they are produced by electrospinning the precursor solution composition according to claim 3 and then heat-treating. In paragraph 5,
The electrospinning is performed while spinning the precursor solution composition at a speed of 1.2 to 1.5 ml/hr under conditions of a voltage of 20 kV and a distance of 20 cm between the nozzle and the ground plate,
The heat treatment is a photolytically active titanium dioxide nanofiber manufacturing method, characterized in that carried out while processing at 180 ~ 210 ° C. for 4 hr or more.

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