KR20110132860A - Making method of tungsten trioxide nano powder having excellent nano dispersion and electrochromism and nano dispersion sol containing tungsten trioxide manufactured by the method - Google Patents

Abstract

PURPOSE: A method for manufacturing tungsten oxide nano-powder and tungsten oxide nano-powder containing nano-dispersion sol manufactured by the same are provided to obtain spherical nano-particle powder of uniform particle sizes in monoclinic crystalline phases. CONSTITUTION: A method for manufacturing tungsten oxide nano-powder includes the following: Unsaturated fatty acid emulsion is introduced into a solution in which a tungsten precursor is dissociated. Nitric acid is dropped into the solution in order to synthesize tungsten hydrate. The tungsten hydrate is used as a washing solvent in order to eliminate remaining materials. The washed tungsten hydrate is filtered and is incinerated to obtain tungsten oxide. Nano-dispersion sol containing the tungsten oxide nano-dispersion sol is composed of the tungsten oxide nano-powder, hydrolyzed TEOS sol, and an organic solvent.

Description

Tungsten oxide nanopowder having excellent nanodispersion and current discoloration characteristics, and a tungsten oxide nanopowder containing nanodispersion sol prepared by this method TRIOXIDE MANUFACTURED BY THE METHOD}

According to the present invention, a tungsten oxide-containing nanodispersion sol is prepared by mixing a metal oxide having a particle size of less than 20 nm in the form of nanoparticle tungsten oxide (WO 3) synthesized by hydrothermal synthesis using unsaturated fatty acid with tetraethylolsosilica (TEOS) and alcohols. Method of preparing a tungsten oxide nano powder excellent in nano-dispersion and current transfer discoloration characteristics, characterized in that the nano-dispersibility is excellent even at a high concentration of 20 to 30% without containing an organic dispersant, unlike the conventional dispersion system and this method The present invention relates to a tungsten oxide nano powder-containing nanodispersion sol prepared by the present invention.

In general, smart windows have a liquid crystal display (LCD), a suspended particle display (SPD), an electrochromic glass (EC), and a photochromic glass, depending on the type of material exhibiting functionality. (PC: Photochromic glass) and Thermochromic glass (LTC: Thermo-chromic glass). Recently, research into the transition from smart windows to smart filming has been actively conducted.

Smart window is a window that can freely adjust the transmittance of sunlight when voltage is applied. Unlike the conventional method of mounting a film having a specific transmittance on the window, the conventional transmittance control technology can freely control the transmittance of sunlight. By applying to a window film having a, it has the advantage of providing a high degree of convenience to the user at the same time as the transmittance of the solar is significantly extended compared to the conventional method of mounting the film.

The window film is a film having an electrochromism characteristic in which a color is reversibly changed depending on an electric field direction when a voltage is applied, and such a film has an optical characteristic of a material due to an electrochemical redox reaction. It is also called an electrochromic material due to a conducting discoloration material, a material that can be reversibly changed.

In particular, in the color change layer, a tungsten oxide coating solution in which peroxo tungsten acid (hereinafter referred to as 'PTA') is dissolved in ethanol is typically used in the reduction electrode layer. The tungsten oxide coating solution is synthesized by first dissolving the tungsten metal powder in 30% hydrogen peroxide water, and then adding ethanol and evaporating from milky white to transparent orange at 80 ° C. The amount of ethanol added at this time is controlled by adding only the amount to obtain a viscosity suitable for the operation of the wet coating. In addition, Na ₂ WO ₄ was ion-exchanged to remove sodium ions, reacted with hydrogen peroxide solution, refluxed with acetic acid, and dried in vacuo at 55 ° C. to synthesize stable acetylated peroxotungstic acid (PTA). In the case of tungsten metal powder, the solution is dissolved in 30% hydrogen peroxide solution, added with 100% acetic acid, then refluxed at 55 ° C., and vacuum dried at 60 ° C. to synthesize pale yellow acetylated PTA. The PTA is dissolved in ethanol to prepare a tungsten oxide coating solution and wet coating to prepare a tungsten oxide thin film.

Looking at the techniques for tungsten oxide coating solution, John P. Cronin et al., In US Pat. No. 5,525,264, describe the use of oxalic acid in the tungsten oxide thin film composition to increase the thickness of the tungsten oxide thin film and prevent cracking of the thin film. It has been disclosed that the reaction rate during coloring and decolorization is high when a small amount of lonic acid, glutaric acid, apicic acid, ethylenedimitrateacetic acid, glycerol, and formamide is added within 10%.

The tungsten oxide coating solution is coated on top of the transparent electrode film (ITO sputter film) in the conducting discoloration film to form a reduction electrode layer, and when the voltage is applied to both electrodes, the reduction electrode layer becomes colored in a transparent state, and again When the electrode is applied, it has a characteristic of changing to a transparent state, but the conventional conventional tungsten oxide coating solution is inferior in electrical stability, that is, it actually loses its characteristics due to the sharp drop in characteristics in cyclic voltammetry durability. It is difficult to use for discoloration film commercialization.

In addition, Korean Patent Laid-Open Publication No. 2007-0016867 discloses an electrochromic coating material and a coating method of coating general PTA on a glass substrate and heat-treating it with amorphous tungsten oxide, but the electrochromic device thus manufactured is a glass substrate. It is not only limited to the PTA, and after heat treatment at 500 ℃ after coating the PTA is not only difficult to apply to a flexible film, but also if using a substrate such as glass, continuous production process is difficult to use the disadvantages of productivity and PTA is difficult to use conventional Problems are shown as they are.

In addition, in order to increase the difference in coloring concentration, it is common to increase the coating thickness in the conventional PTA coating. When the coating thickness is increased, the PTA is an amorphous inorganic material, so that cracks are generated on the coated surface, resulting in deterioration of adhesion. Alternatively, the surface is brittle, and problems occur in the electrical redox reaction due to cracks, and thus no coloration occurs.

In addition, in order to overcome these problems, the conventional PTA has been reported to bake the PTA-coated film to a high temperature again. Even though the PTA is fired, the problems are not solved. When the PTA coated film is calcined again, a temperature of about 150 to 200 ° C. is applied. It is natural that the thermal deformation of the film substrate is caused by the sintering process. Also, when the ITO-sputtered film is heated to a high temperature on the substrate of the electrochromic film, the organic matter and moisture remaining in the plastic film At this time, a dense metal ITO layer is formed on the surface, and the residual impurities that cannot be evaporated due to low water or gas permeability remain and remain on the film. It becomes difficult to use.

Therefore, in order to solve the above problems, the development of a PTA that exhibits excellent characteristics of fast coloring and decolorization rate in comparison with a conventional PTA in particular with respect to a reduction electrode layer of an electrically conductive color change film is urgently required.

The present invention has been made to solve the above problems, by adding an unsaturated fatty acid dispersion emulsion to a solution dissociated tungsten precursor to synthesize tungsten oxide nanoparticles by hydrothermal synthesis method, the yield of the final product is high, uniform particle size It is possible to obtain a spherical nanoparticle powder having a monoclinic (monoclinic) crystal phase having a, tungsten oxide nano powder excellent in nano dispersion and current transfer discoloration characteristics, characterized in that the synthesis method is simpler than the conventional PTA synthesis method, the productivity is high. The object of the present invention is to provide a method for producing the same.

The present invention is a tungsten oxide nanopowder of high concentration using a ball mill using zirconium beads, a mixture of a tungsten oxide nanopowder prepared by the above method in a hydrolyzed TEOS (Tetra Ethyl Ortho Silicate) sol and an organic solvent Another object of the present invention is to provide a tungsten oxide nanopowder-containing nanodispersion sol, which is characterized in that it exhibits excellent electrochromism characteristics and does not gel with sufficient stability.

Therefore, the present invention synthesizes the nanoparticles having the crystallinity of the WO3 inorganic oxide to secure cycle durability, and solved by nanoparticles of porous WO3 oxide to improve the coloring speed accompanying the disadvantages in the crystalline particles. At the same time, when the organic dispersant is included in the nano-dispersion sol, the film does not express the conduction discoloration function. Therefore, the organic dispersant is not used at all, so the conduction discoloration function is excellent. It is characterized by being applicable to a synthetic resin film having.

The present invention for solving the above problems is the synthesis step (S1) of the tungsten hydrate to add an unsaturated fatty acid emulsion to the solution dissociated tungsten precursor, dropping nitric acid;

The tungsten hydrate is a washing step (S2) to remove the residual material using a washing solvent;

Calcination step (S3) of filtering the washed tungsten hydrate to heat treatment at high temperature to produce tungsten oxide;

Method for producing a tungsten oxide nano powder comprising a as a problem solving means.

And the present invention is a tungsten oxide nano powder containing tungsten oxide nano powder prepared by the above method, 5 to 10% by weight of hydrolyzed TEOS sol, 60 to 75% by weight of an organic solvent containing tungsten oxide nano powder containing The nanodispersion sol is another means for solving the problem.

According to the present invention by the above-mentioned means for solving the problem, by producing a tungsten precursor by a hydrothermal synthesis method using an unsaturated fatty acid, it is possible to obtain a spherical but spherical nanoparticle powder having a monoclinic crystal phase, the conventional PTA synthesis method Compared with the simple synthesis method, the productivity is high, and the tungsten oxide nano powder-containing nanodispersion sol prepared by mixing the nanoparticle powder with hydrolyzed TEOS sol and an organic solvent and pulverizing by ball mill does not use any organic dispersant. It is expected that the application range will be broadly expanded since it is excellent in the conduction discoloration function, and can be applied to a synthetic resin film having flexibility since it can be heat treated by low temperature after coating on the film.

1 is a block diagram showing a method for producing a tungsten oxide nano powder using an unsaturated fatty acid according to an embodiment of the present invention,
2 is a SEM photograph of the tungsten oxide nanoparticles of Example 1,
3 is an XRD graph of tungsten oxide nanoparticles of Example 1,
4 is a TEM photograph of a dispersion sol containing tungsten oxide nanoparticles of Example 1,
FIG. 5 relates to a cyclovoltammetry (CV) graph of a film containing tungsten oxide nanoparticles of Example 1. FIG.

Hereinafter, a method for preparing tungsten oxide nanopowder having excellent nanodispersion and current discoloration characteristics according to the present invention, and a preferred embodiment of the tungsten oxide nanopowder-containing nanodispersion sol prepared by the method, FIGS. 1 to 5 It will be described in detail with reference to.

According to an embodiment of the present invention, the tungsten oxide nano powder-containing nanodispersion sol coated to form the reduction electrode layer of the electrochromic film includes tungsten oxide nanoparticle powder, and the tungsten oxide nanoparticle powder is made of unsaturated fatty acid. It is characterized in that it is produced by a hydrothermal synthesis method.

Referring to the method of manufacturing the tungsten oxide nano powder excellent in nano-dispersion and current transfer discoloration characteristics according to the present invention.

Referring to Figure 1, tungsten oxide nano powder according to the present invention is a step (S1) of the synthesis of tungsten hydrate to add an unsaturated fatty acid emulsion to the solution dissociated tungsten precursor, dropping nitric acid;

The tungsten hydrate is a washing step (S2) to remove the residual material using a washing solvent;

Calcination step (S3) of filtering the washed tungsten hydrate to heat treatment at high temperature to produce tungsten oxide;

Characterized in that it comprises a.

In the present invention, in the tungsten hydrate synthesis step (S1), 90-100 g of tungsten precursor selected from tungsten chloride, tungsten sulfate, tungsten alkoxide and tungsten alkylate is added to a reactor in which 1000 ml of distilled water is prepared, followed by a temperature of 78 to 82 ° C. Heated to completely dissociate the tungsten precursor. At this time, when the heating temperature is lower than the temperature range defined above, there is a concern that the tungsten precursor may not be sufficiently dissociated in distilled water, and when the temperature is exceeded above, there is an advantage in dissociating the starting material. When synthesized into particles, there is a fear of forming coarse particle size.

In addition, an emulsion prepared by adding 90-100 g of unsaturated fatty acid to 500 ml of distilled water and stirring was added to a solution in which the tungsten precursor dissociated above. Then, 38-42 g of nitric acid was added dropwise for 1 hour, and the reactant gradually became white to yellow. Tungsten hydrate is produced as it turns into precipitates.

In this case, the unsaturated fatty acid used may be selected from one or more selected from the group consisting of soft oil fatty acid, dehydrated castor oil, coconut oil fatty acid, soybean oil fatty acid, stone oil fatty acid, oleic acid or linoleic acid.

The microemulsion formed by the phase separation of the unsaturated fatty acid and water is a simple method of producing spherical droplets in the reaction and synthesizing the nanoparticles by adjusting the pH in the droplets. It is easy to control the size of nanoparticles, and the nanoparticle hydrate in the state of containing unsaturated fatty acid remains on the particle surface even after washing, so that it can be dispersed in high concentration even without dispersant in preparing the final nanodispersion sol. .

In the tungsten hydrate synthesis step (S1) is synthesized at a temperature of 70 ~ 80 ℃, the overall synthesis time is preferably synthesized for 1 to 5 hours depending on the synthesis amount and synthesis conditions.

And in the tungsten hydrate washing step (S2) is a process of washing the unreacted by-products and unsaturated fatty acids when synthesizing the tungsten hydrate in the synthesis step (S1) of the tungsten hydrate, the cleaning solvent using alcohols, 3 ~ 5 hours ultrasonic It is preferable to wash. At this time, if the ultrasonic cleaning time is less than the time range defined above, unreacted by-products and unsaturated fatty acids remaining in tungsten hydrate may not be sufficiently washed. Heat is generated by vibrations inside, and the generated internal heat may cause unwanted side reactions.

The washing solvent used in the present invention is preferably used by selecting one or more from ethanol, methanol, isopropyl alcohol or butanol.

And in the tungsten oxide calcination step (S3) is a step of calcining the tungsten hydrate passed through the washing step (S2) at a high temperature in the calcined in air for 1-6 hours at a temperature of 250 ~ 350 ℃, crystallinity of monoclinic system It is characterized by forming and increasing the density of the remaining hydroxyl groups and crystallinity, but calcination at a temperature lower than the general calcination temperature, but the desired crystallinity can be obtained at low temperatures by the catalytic role of unsaturated fatty acids.

When the calcination condition is less than the calcination condition range defined above, it is difficult to obtain monoclinic crystalline tungsten oxide and there is a possibility that it becomes amorphous tungsten oxide, and when the calcination condition range defined above is nano Agglomeration between particles is prominent, which makes it difficult to obtain a desired nanoparticle size.

Therefore, by incorporating an unsaturated fatty acid dispersion emulsion into a solution in which the tungsten precursor is dissociated by the method described above, and synthesizing the tungsten oxide nanoparticles by hydrothermal synthesis method, the yield of the final product is high and the particle size is 10-20 nm uniform. A spherical nanoparticle powder having a monoclinic crystal phase of particle size can be obtained, and the synthesis method is simpler than the conventional PTA synthesis method and is characterized by high productivity.

Hereinafter, the tungsten oxide nanopowder-containing nanodispersion sol prepared using the tungsten oxide nanopowder prepared by the above method will be described in detail.

The tungsten oxide nano powder-containing nanodispersion sol according to the present invention comprises 20 to 30 wt% of the tungsten oxide nano powder prepared by the above method, 5 to 10 wt% of the hydrolyzed TEOS sol, and 60 to 75 wt% of the organic solvent. It is characterized by.

In the present invention, the tungsten oxide nano powder exhibits a current discoloration characteristic, when the content of the tungsten oxide nano powder is less than 20% by weight, the current discoloration function of the nanodispersion sol may be deteriorated, and the content of the tungsten oxide nano powder may be reduced. If it exceeds 30% by weight, the content of TEOS sol is relatively low, so the stability of nano-dispersed sol may be reduced, and the dispersion may be rapidly gelled, or the coating workability decreases due to the increase of viscosity due to the low content of organic solvent. There is a concern.

The hydrolyzed TEOS sol exhibits steric hindrance and surface charge to generate repulsive force between the nanoparticles, acting as a dispersant of the nano-dispersed sol and acting as a binder when coated on the base film. If the content of the sol is less than 5% by weight, there is a possibility that the adhesive force is lowered due to the action of the substrate as a binder, and when the content of the TEOS sol is more than 10% by weight, surface cracks are easily formed when the substrate is coated. It may occur.

The hydrolyzed TEOS sol is preferably added to 20 to 25 parts by weight based on 100 parts by weight of distilled water and then adjusted to pH 2 by adding hydrochloric acid.

The organic solvent serves to disperse the tungsten oxide nano powder and the hydrolyzed TEOS sol, and when the content of the organic solvent is less than the range defined above, the tungsten oxide nano powder and the hydrolyzed TEOS sol are dissolved in the organic solvent. May not be sufficiently dispersed, and when the content of the organic solvent exceeds the above-defined range, there is a concern that the conduction discoloration function may decrease as the content of the tungsten oxide nanopowder and the hydrolyzed TEOS sol decreases. Or there is a fear that a sufficient film formation thickness cannot be obtained.

The organic solvent used in the present invention is preferably selected from one or more of methanol, ethanol, butanol, pentanol, and propanol as primary alcohols.

In the tungsten oxide nano powder-containing nanodispersion sol according to the present invention, the nanodispersion sol is filled with a mixture of tungsten oxide nanopowder, hydrolyzed TEOS sol and an organic solvent in a ball mill container and zirconium beads having a size of 0.3-0.5 mm. Filling 65-75% by volume of the filling amount and dispersing for 72-96 hours, a nano dispersing sol in which tungsten oxide nano powder is uniformly dispersed in an organic solvent is prepared.

If the filling amount of the zirconium beads or the ball mill dispersion time is less than the range defined above, there is a fear that the tungsten oxide nano powder is not uniformly dispersed in the organic solvent sufficiently, and the filling amount of the zirconium beads or the ball mill If the dispersing time exceeds the above-defined range, the tungsten oxide nanopowder may be inefficient because the dispersing effect in the organic solvent is no longer remarkably improved.

Accordingly, the tungsten oxide nano powder-containing nanodispersion sol according to the present invention has a high concentration of tungsten oxide solid content of 20 to 30%, excellent dispersion stability, and the hydrolyzed TEOS is an inorganic binder. It can be directly coated on a plastic substrate without a manufacturing step.

Hereinafter, a method for preparing tungsten oxide nanopowder having excellent nanodispersion and current discoloration characteristics and a tungsten oxide nanopowder-containing nanodispersion sol prepared by the method will be described in detail with reference to the following examples. The present invention is not necessarily limited only by the following examples.

1. Preparation of Tungsten Oxide Nano Powder Containing Nano Dispersing Sol and Coating

(Example 1)

As a starting material for the synthesis of tungsten oxide nanoparticles, tungsten chloride, tungsten sulfide, tungsten alkoxide, and tungsten alkylated 90 g of tungsten chloride and 1000 ml of distilled water were put in a prepared reactor and heated to 80 ° C. for complete dissolution. Next, after putting 90 g of oleic acid into 500 ml of distilled water and stirring, the solution was changed into a white emulsion, which was added to the reactor, and 40 g of nitric acid was added dropwise for 1 hour. The reactants gradually change from white to yellow precipitates. The finished compound was filtered using a paper filter, and the filtered reaction product was poured into 300 ml of methanol and stirred. Tungsten oxide powder obtained by filtration after washing for 5 hours and filtered at 350 ° C. for 6 hours in an electric furnace was dark brown, and the powder of tungsten oxide 30 g, hydrolyzed in a ball mill to prepare a dispersion sol. 5 g of TEOS and 65 g of ethanol were respectively weighed, 400 g of zirconium 0.5 mm beads were added, and ball mill dispersion was performed for 96 hours to obtain a final tungsten oxide dispersion sol. In order to confirm the CV characteristics, a sample film was prepared by coating 500 nm on an ITO film having a thickness of 188 μm and having a sheet resistance of 100 μs / sq. At 500 ° C. for 1 minute.

(Example 2)

In Example 1, a sample film was prepared under the same conditions as in Example 1 except that 90 g of tungsten sulfate was added instead of tungsten chloride as a starting material in the tungsten oxide particle synthesis process. )

(Example 3)

In Example 1, a sample film was prepared under the same conditions as in Example 1 except that 300 ml of ethanol was added instead of ethanol in the washing step of preparing the tungsten oxide particle synthesis process (that is, the solubility of the oleic acid than the methanol of Example 1). Slightly lower ethanol was added to the replacement.)

(Example 4)

In Example 1, a sample film was prepared under the same conditions as in Example 1 except that 90 g of linoleic acid was added instead of oleic acid in the tungsten oxide particle synthesis process. It was replaced with Iksan.)

(Comparative Example 1)

In Example 1, a sample film was prepared under the same conditions as in Example 1 except that 300 ml of distilled water was added instead of ethanol in the washing step of the tungsten oxide particle synthesis process. Has been committed.)

2. Evaluation of the Test Piece

In order to demonstrate the effects of the tungsten oxide high concentration nanodispersion sol of Examples 1 to 4 and Comparative Example 1 according to the present invention, the tungsten oxide particles, monoclinic crystallinity of tungsten oxide and the best cyclovoltammetry (CV) graph are shown. Conditions were carried out according to the following test method.

end. Observation of Synthetic Particle Size

Test purpose: Determination of tungsten oxide particle size according to the invention

-Test condition: The particle observation photograph is a HITACHI (JAPAN) S-2400 scanning electron microscope (SEM) image, taken at 100000 times magnification at 15 kV.

According to the above method, as a result of observing the synthetic particle sizes of Examples 1 to 4 and Comparative Example 1, it was confirmed that the particle size was 20 to 30 nm, and the particle shape showed a uniform round shape.

For reference, Figure 2 is a SEM photograph of the tungsten oxide particles synthesized by hydrothermal synthesis method using the unsaturated fatty acid of Example 1. As shown in Figure 2 the size of the particles produced by the method of Example 1 was 20 ~ 30nm, it was confirmed that the particle shape shows a uniform round shape. Therefore, Examples 1 to 4 and Comparative Example 1 was found to be well synthesized round spherical tungsten oxide nanoparticles.

I. Observation of XRD Crystallinity

-Test purpose: Confirmation of monoclinic crystallinity of tungsten oxide particles according to the present invention

Test conditions: XRD observations were measured using PHILIPS (Netheland), X'Pert-MPD System.

According to the above method, the crystallinity of the tungsten oxide compound synthesized by the hydrothermal synthesis method using the unsaturated fatty acids of Examples 1 to 4 and Comparative Example 1 was confirmed to be well synthesized with monoclinic crystallinity.

For reference, Figure 3 is an XRD graph showing the crystallinity of the tungsten oxide compound synthesized by the hydrothermal synthesis method using the unsaturated fatty acid of Example 1. The XRD values of Example 1 were 223.1 at 0.0.2, 223.8 at 0.2.0, 224.3 at 2.0.0, 233.55 at 2.0.2, 228.6 at 1.1.2, 228.9 at 1.2.1 As a result, it was confirmed that the tungsten oxide compound was well synthesized by monoclinic crystallinity.

All. Observation of Dispersed Sol Particles

-Test purpose: Confirmation of dispersibility and particle size of tungsten oxide dispersion sol according to the present invention

-Test conditions: The particle observation photograph is JEOL (Japan). JEM-2010 Transmission Electron Microscope (TEM) image, taken at 15kV at 100000x magnification.

According to the method described above, the dispersed sol particles prepared by the methods of Examples 1 to 4 and Comparative Example 1 had a monodisperse image of 20 to 30 nm, and were well distributed in the shape of round particles. I could confirm it.

For reference, FIG. 4 is a TEM photograph of a sol dispersed in tungsten oxide particles synthesized by hydrothermal synthesis using the unsaturated fatty acid of Example 1. FIG. As shown in FIG. 4, the distribution of the size of the particles dispersed by the method of Example 1 was a monodisperse image of 20-30 nm, and it was confirmed that the particles were well distributed in the shape of round particles. Therefore, it was found that the tungsten oxide nanoparticles in the form of round spheres were well dispersed.

la. Observation of cyclovoltammetry (CV) graph

-Test Purpose: To identify the characteristics of cyclovoltammetry (CV) in the tungsten oxide thin film prepared according to the present invention.

Test conditions: A half cell apparatus was used in which a tungsten oxide-coated film was used as a cathode (working electrode), platinum (relative electrode), and Ag / AgNO ₃ (reference electrode), and a -1.2 at a sweep rate of 50 mV / s was used. It measured in the range of V-0.8V.

According to the above method, as a result of confirming the cyclovoltammetry (CV) characteristics of the coating films prepared by the methods of Examples 1 to 4 and Comparative Example 1, in Examples 1 to 4 where the CV characteristics are good, it is stable without changing the cycle area. While the change curve is shown, Comparative Example 1 shows a change in cycle charge area, which results in poor electrical durability.

For reference, FIG. 5 is a graph measuring the cyclovoltammetry (CV) characteristics of a film coated with a sol dispersed with tungsten oxide particles synthesized by hydrothermal synthesis using unsaturated fatty acid of Example 1, and the x axis represents ± voltage, The Y axis is represented by the amount of current. Therefore, when the voltage is picked up positively and negatively, the amount of current to be received is different, resulting in an overall curve, and the slope of the curve is mainly a measure of the movement speed of the current amount and the coloration and discoloration speed in EC.

hemp. In situ transmittance measurement

-Test purpose: To confirm the conduction discoloration characteristics of the tungsten oxide thin film prepared according to the present invention

Test conditions: A half cell device was used in which a tungsten oxide-coated film was used as a cathode (working electrode), platinum (relative electrode), and Ag / AgNO ₃ (reference electrode). The results of measurement of transmittance change at 650 nm using UV-Vis spectrophotometer during coloring for 30 seconds at + 1V are as shown in Table 1 below.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Color transmittance%
(650 nm)
9
13
15
12
17 Decolorization transmittance%
(650 nm)
83
83
81
78
76

Referring to Table 1, it can be seen that the optical properties of Example 1 and Example 3 is good, and in particular, Example 1 is the best optical properties. That is, in Example 1, most of the remaining unsaturated fatty acids are removed by using methanol having high solubility of oleic acid in the washing step, whereas in Example 3, residual unsaturated fatty acids are not completely removed using ethanol, so there is a slight difference in optical characteristics. In view of these results, it was confirmed that the results showed a difference in the measurement results due to the sensitive action depending on the conditions in the particle synthesis.

In the above, the Applicant has described preferred embodiments of the present invention, but these embodiments are merely one embodiment for implementing the technical idea of the present invention, and any modifications or modifications may be made as long as the technical idea of the present invention is implemented. Should be interpreted as being within the scope.

S1: Tungsten Hydrate Synthesis Step S2: Tungsten Hydrate Wash Step
S3 tungsten oxide calcining step

Claims (8)

A step of synthesizing a tungsten hydrate in which an unsaturated fatty acid emulsion is added to a solution in which the tungsten precursor is dissociated, and nitric acid is added dropwise;
The tungsten hydrate is a washing step of removing residual material using a washing solvent;
Calcination step of filtering the washed tungsten hydrate and heat treatment at high temperature to produce tungsten oxide;
Tungsten oxide nano powder production method comprising a.
The method of claim 1,
The unsaturated fatty acid may be prepared by using one or more selected from the following: fatty acid, dehydrated castor oil, coconut oil fatty acid, soybean oil fatty acid, dol oil fatty acid, oleic acid or linoleic acid. Way.
The method of claim 1,
The tungsten hydrate synthesis step is a tungsten oxide nano powder production method characterized in that the synthesis for 1 to 5 hours at a temperature of 70 ~ 80 ℃.
The method of claim 4, wherein
The washing solvent is a method for producing tungsten oxide nano powder, characterized in that one or more selected from ethanol, methanol, isopropyl alcohol or butanol.
The method of claim 1,
The calcination step is a tungsten oxide nano powder manufacturing method, characterized in that the calcination treatment in air for 1 to 6 hours at a temperature of 250 ~ 350 ℃.
20 to 30% by weight of tungsten oxide nano powder prepared by the method of any one of claims 1 to 5, 5 to 10% by weight of hydrolyzed TEOS sol, 60 to 75% by weight of an organic solvent Tungsten oxide nano powder-containing nanodispersion sol.
The method according to claim 6,
The hydrolyzed TEOS sol is tungsten oxide nano powder-containing nano-dispersion sol, characterized in that adjusted to pH 2 by adding 20 to 25 parts by weight based on 100 parts by weight of distilled water.
The method according to claim 6,
The nano-dispersion sol is filled with a mixture of tungsten oxide nano powder, a hydrolyzed TEOS sol and an organic solvent in a ball mill container and zirconium beads of 0.3 ~ 0.5 mm size to fill 65 ~ 75% by volume of the mixture filling amount, 72 ~ 96 Tungsten oxide nano powder-containing nano dispersion sol, characterized in that dispersed for time.

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