WO2022105052A1

WO2022105052A1 - Nano zirconia powder, preparation method therefor, and dispersion liquid and optical film obtained

Info

Publication number: WO2022105052A1
Application number: PCT/CN2021/072367
Authority: WO
Inventors: 张曦; 张兵; 宋锡滨
Original assignee: 山东国瓷功能材料股份有限公司
Priority date: 2020-11-23
Filing date: 2021-01-18
Publication date: 2022-05-27
Also published as: JP7348956B2; CN112429771A; TW202220931A; JP2022553585A; CN112429771B

Abstract

The present application provides a nano zirconia powder having a particle size of 3-10 nm and a specific surface area of 200-240 m2/g. The nano zirconia powder comprises tetragonal zirconia, and the proportion of tetragonal zirconia is 60-95% of the powder. The nano zirconia powder provided by the present application has the characteristics of small particle size, large specific surface area, good particle monodispersion effect, tetragonal main crystal phase, etc. The dispersion liquid obtained by dispersing in water can greatly increase the refractive index of the refractive coating and improve the performance of a film in the subsequent preparation of, for example, a brightness enhancement film or an anti-reflection film.

Description

Nano zirconia powder, its preparation method and obtained dispersion liquid, optical film

Nano zirconia powder, preparation method thereof and dispersion liquid and optical film prepared therefrom

This application claims the priority of the Chinese patent application filed on November 23, 2020, with the application number of 202011320008.8 and the invention titled "nano-zirconia powder, its preparation method and the resulting dispersion, and optical film". The entire contents of this application are incorporated by reference.

technical field

The application belongs to the field of fine chemicals, and in particular relates to a nano-zirconia powder, a preparation method thereof, a dispersion liquid obtained therefrom, and an optical film.

Background technique

In recent years, by combining zirconia particle dispersions with transparent resins or films, taking advantage of its high refractive index, it has been well used in the optical field. For example, high-refractive zirconia dispersion is used to prepare optical films such as brightness enhancement film and anti-reflection film, which can be used on LCD displays to increase the brightness and clarity of the screen; it can also be used to improve the refractive index of LED sealing resin, which can more effectively Capture the light emitted by the illuminator, thereby increasing the brightness of the LED. In conclusion, its high refractive properties can be used in high refractive coatings in different fields.

The refractive index of the zirconia dispersion is closely related to the particle size, crystal structure, particle dispersion state and preparation process of the nano-zirconia in the system. Chinese patent application CN108529674A discloses a preparation method of high-dispersion nano-zirconia particles and transparent dispersions thereof. Nano-zirconia particles are directly prepared by pyrolyzing inorganic zirconium salts in a hypergravity environment. The improvement of the agglomeration is greatly reduced, and after washing and modification, it is directly a transparent zirconia liquid dispersion. Although the zirconia prepared by this method has a small particle size and good dispersibility, its powder crystal structure is a monoclinic phase, and the refractive index of the powder is much lower than that of the tetragonal powder, and the corresponding liquid phase dispersion The refractive index of the bulk is also lower under the same conditions.

SUMMARY OF THE INVENTION

The application provides a nano-zirconia powder, its preparation method, the obtained dispersion liquid, and the specific technical solutions of the optical film as follows:

A nano-zirconia powder, the particle size of the nano-zirconia powder is 3-10nm, the specific surface area is 200-240m ² /g, the nano-zirconia powder comprises zirconia with a tetragonal crystal structure, And the proportion of zirconia with tetragonal crystal structure accounts for 60-95% of the powder.

The application also provides a method for preparing nano-zirconia powder according to the above technical solution, comprising the following steps:

Dissolving zirconium salt and stable element salt together in water to obtain solution A;

The base is dissolved in water to obtain solution B;

The solution A and the solution B are fully mixed under stirring to form a precipitate, wherein the mass of the precipitate accounts for 1-40% of the mass of the total mixed solution; after the precipitate is washed and filtered for many times, the precursor C is obtained;

Add water and organic acid or its salt to the former body C to make pulp, and the total solid content in the obtained pulp is 6-20wt%;

The above obtained slurry is put into a reaction kettle, the filling amount is 60-90%, and the hydrothermal reaction is carried out at 180°C-220°C for 1-12 hours, and a reaction solution is obtained after the reaction;

The reaction solution is directly dried or concentrated, washed and then dried to obtain nano-zirconia powder.

Preferably, the added zirconium salt is a water-soluble zirconium salt selected from at least one of basic carbonate, carbonate, nitrate, acetate, chloride and oxychloride; the added stability The elemental salt is a chloride or nitrate of a stable element, wherein the stable element is selected from at least one of aluminum, magnesium, titanium and rare earth elements; the base is selected from ammonia water, sodium hydroxide, potassium hydroxide and at least one of lithium hydroxide.

Preferably, the added zirconium salt concentration is less than or equal to 2 mol/L, the molar concentration ratio of the added stability element to the zirconium element is 2/98 to 30/70, and the added alkali concentration is less than or equal to 8 mol/L.

Preferably, the organic acid is selected from at least one of monocarboxylic acid, polycarboxylic acid and hydroxycarboxylic acid, wherein the monocarboxylic acid is selected from at least one of formic acid, acetic acid, propionic acid and butyric acid, The polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid and phthalic acid, and the hydroxycarboxylic acid is selected from at least one of lactic acid, malic acid, tartaric acid and citric acid; the salt of the organic acid Its alkali metal salt is at least one selected from potassium salt and sodium salt.

Preferably, the molar concentration of the added organic acid or its salt is 10-100% of the total molar concentration of zirconium element and stabilizing element.

Preferably, when the boiling point of the added organic acid is less than 150°C, the reaction solution is directly dried to obtain nano-zirconia powder; when the boiling point of the added organic acid is greater than 150°C, the reaction solution is concentrated and washed for many times and then dried. A nano-zirconia powder is obtained.

Preferably, the drying method is selected from any one of vacuum low-temperature drying, drying and spraying, and the concentrated washing method is selected from any one of ultrafiltration, rotary evaporation and ceramic membrane concentrated washing.

The application also provides a dispersion liquid containing the nano-zirconia powder described in the above technical solution, the refractive index of the dispersion liquid is 1.343-1.472, and the dispersion liquid has a positive Zeta potential value under the condition of pH≤7. The content of nano-zirconia in the dispersion liquid is 5-60wt%.

Preferably, the dispersion liquid is under the condition of pH≤7, and the dispersion liquid is under the condition of pH≤7, and the Zeta potential value is in the range of 0-60mv.

Preferably, the dispersion is obtained by concentrating and washing the reaction solution obtained by the preparation method described in the above technical scheme to remove the organic acid or its salt, or by dispersing the nano-zirconia powder prepared by the above technical scheme obtained in water.

The present application also provides an optical film, which is prepared by using the dispersion liquid containing nano-zirconia powder according to any one of the above technical solutions.

The present application also provides an application of the nano-zirconia powder according to the above technical solution or the dispersion liquid containing the nano-zirconia powder according to any of the above technical solutions in preparing an optical film.

Compared with the prior art, the beneficial effects of the present application are:

1. The nano-zirconia powder provided by this application has the characteristics of small particle size, large specific surface area, good particle monodispersion effect, and the main crystal phase is tetragonal;

2. The dispersion liquid prepared by using the nano-zirconia powder obtained above has stable system, uniform dispersion and high refractive index. Its refractive index can not only reach 1.343-1.472, but also has a large positive Zeta potential under the condition of pH≤7 value;

3. The use of the dispersion liquid with the above characteristics can greatly increase the refractive index of the high-refractive coating and improve the performance of the film in the subsequent preparation of, for example, a brightness enhancement film or an anti-reflection film.

Description of drawings

Figure 1a is a transmission electron microscope Figure 1 of the nano-zirconia powder provided in Example 1 of the application;

Figure 1b is a transmission electron microscope Figure 2 of the nano-zirconia powder provided in Example 1 of the application;

Fig. 2 is the XRD contrast pattern of the nano-zirconia powder provided by the embodiment 1 of the application and the standard tetragonal phase grain;

3 is a particle size distribution diagram of the nano-zirconia powder provided in Example 1 of the present application;

4 is a scanning electron microscope image of the nano-zirconia powder provided in Comparative Example 1 of the present application.

Detailed ways

The technical solutions of the present application will be described in detail below in conjunction with specific embodiments, however, it should be understood that elements, structures and features in one embodiment can also be beneficially combined into other embodiments without further description.

It should be understood that although the embodiments may show a specific order of method steps, this does not require or imply that these operations must be performed in this specific order, unless otherwise specified or the relationship between the steps determines the order of execution . Such variants will depend on the choice. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined to be performed as one step, and/or one step may be decomposed into multiple steps to be performed. All such variations are within the scope of this disclosure.

The described embodiments are only to describe the preferred embodiments of the present application, not to limit the scope of the present application. On the premise of not departing from the design spirit of the present application, various modifications made by those of ordinary skill in the art to the technical solutions of the present application and improvements, shall fall within the scope of protection determined by the claims of this application.

An embodiment of the present application provides a nano-zirconia powder, the particle size of the nano-zirconia powder is 3-10 nm, the specific surface area is 200-240 m ² /g, and the nano-zirconia powder includes a tetragonal The zirconia with phase crystal structure, and the proportion of zirconia with tetragonal crystal structure accounts for 60-95% of the powder.

The nano-zirconia powder provided by this embodiment has small particle size, large specific surface area, and high refractive index, and can prepare a nano-zirconia dispersion liquid with uniform dispersion and high refractive index. The nano-zirconia powder provided in the above embodiment, the synergistic effect of its particle size, specific surface area and the proportion of the tetragonal crystal structure can make the obtained nano-zirconia powder have the characteristics of uniform dispersion and high refractive index after dispersion. Specifically, when the particle size is small and the specific surface is large, the particle dispersibility is good, the prepared aqueous dispersion will be uniformly dispersed, and the refractive index will be higher; and when the zirconia crystal phase is a tetragonal phase and the powder The higher the proportion of the tetragonal phase, the higher the corresponding refractive index (the refractive index of zirconia in the tetragonal phase is 2.40, which is significantly higher than the refractive index of zirconia in the monoclinic phase, which is 2.02). It can be understood that the particle size of the nano-zirconia powder can also be 4, 5, 6, 7, 8, 9 nm or any value within the above range, and the specific surface area can also be 205, 210, 215, 220, 225 , 230, 235 m ² /g or any value within the above range, the proportion of the tetragonal crystal structure in the powder can also be 65, 70, 75, 80, 85, 90% or any value within the above range.

Another embodiment of the present application also provides the preparation method of the nano-zirconia powder described in the above embodiment, comprising the following steps:

The base is dissolved in water to obtain solution B;

In the preparation method of the nano-zirconia powder defined in the above-mentioned embodiments, the order of adding the organic acid or its salt is different from the prior art, that is, the organic acid or its salt needs to be introduced before pulping instead of after pulping. Because of the effect of electric charge before pulping, the viscosity of the precursor will be greatly reduced during the pulping process, which can not only improve the pulping and dispersion effect, but also increase the concentration of the precursor into the kettle, avoiding the poor pulping and dispersion effect. , resulting in high particle size of the prepared powder and agglomeration, not easy to disperse and other defects. In addition, it has been reported in the prior art that the hydrothermal reaction can be carried out above 170°C, and this embodiment limits its temperature within the range of 180-220°C, such as 190°C, 195°C, 200°C, 205°C, 210°C. °C, 215 °C or any point within the above range. The temperature of the hydrothermal reaction in the preparation method provided by this embodiment directly affects the crystal grain structure of the obtained powder, that is, if it is less than 180° C., for example, 170° C., the crystal form of the obtained powder is a monoclinic phase grain structure, while Unexpected tetragonal crystal structure; and if it is more than 220 ° C, the requirements for production equipment are strict, which is not conducive to scale-up production.

As a preferred embodiment, the added zirconium salt is a water-soluble zirconium salt, selected from at least one of basic carbonate, carbonate, nitrate, acetate, chloride, and oxychloride; The added stabilizing element salt is chloride or nitrate of stabilizing element, wherein the stabilizing element is selected from at least one of aluminum, magnesium, titanium and rare earth elements; the alkali is selected from ammonia water, sodium hydroxide , at least one of potassium hydroxide and lithium hydroxide.

As a preferred embodiment, the concentration of the added zirconium salt is ≤2mol/L, the molar concentration ratio of the added stability element and the zirconium element is 2/98～30/70, and the concentration of the added alkali is ≤8mol/L L. It can be understood that the amount of the above-mentioned added stabilizing elements needs to be strictly controlled, and it should not be too much or too little, because too little is easy to make the tetragonal phase of the prepared powder account for a small or even a monoclinic phase. If it is too large, the content of stabilizing elements in the prepared powder is likely to be high, which will affect the refractive index of the powder itself. By controlling the added zirconium salt concentration and the amount of the stabilizing element salt, the molar concentration ratio of the stabilizing element and the zirconium element in solution A is strictly controlled.

As a preferred embodiment, the organic acid is selected from at least one of monocarboxylic acid, polycarboxylic acid and hydroxycarboxylic acid, wherein the monocarboxylic acid is selected from formic acid, acetic acid, propionic acid and butyric acid At least one, the polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, and phthalic acid, and the hydroxycarboxylic acid is selected from at least one of lactic acid, malic acid, tartaric acid, and citric acid; the The salt of the organic acid is an alkali metal salt, at least one selected from potassium salt and sodium salt.

As a preferred embodiment, the molar concentration of the added organic acid or its salt is 10-100% of the total molar concentration of zirconium element and stable element. It can be understood that, in this embodiment, the content of organic acid and its salt is clearly defined, and the molar concentration of organic acid and its salt is limited to 10-100% of the total molar concentration of zirconium element and stable element. The reason is that, in the prior art (for example, Chinese patent application CN102264645A), when preparing the zirconia dispersion, the amount of the organic acid added is usually more than 1 times the molar concentration of zirconium, but when the organic acid, especially the molecular weight, is added The amount is too large. On the one hand, the acidity of the reaction slurry is highly corrosive to the reaction equipment. On the other hand, the preparation of the aqueous dispersion in the later stage needs to be concentrated and washed with a large amount of water for many times, and the water waste is serious. More importantly, the larger the amount of acid The higher the probability of acid content remaining in the solvent-based dispersion prepared later, it is not conducive to industrial production. Therefore, in this embodiment, the amount is limited within the range of 10-100% through the optimization of the overall scheme. Preferably, the molar concentration of the organic acid and its salt can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of the sum of the molar concentration of zirconium element and stable element, or within the above range any point value.

As a preferred embodiment, when the boiling point of the organic acid added is less than 150°C, the reaction solution is directly dried to obtain nano-zirconia powder; when the boiling point of the organic acid added is greater than 150°C, the reaction solution is concentrated and washed for many times. and then dried to obtain nano-zirconia powder. It can be understood that the organic acid with a boiling point of <150°C can be selected from, for example, formic acid, acetic acid, propionic acid, etc., and the organic acid with a boiling point of >150°C can be selected from, for example, oleic acid, citric acid, isovaleric acid, etc., which are only listed here. There is no specific limitation.

As a preferred embodiment, the drying method is selected from any one of vacuum low-temperature drying, drying and spraying, and the concentrated washing method is selected from any one of ultrafiltration, rotary evaporation and ceramic membrane concentrated washing. It can be understood that the above drying methods and concentrated washing methods are operation methods that are well known to those skilled in the art, and the specific requirements of the specific methods can be selected or adjusted according to the actual situation.

An embodiment of the present application also provides a dispersion liquid comprising the nano-zirconia powder described in the above embodiment, the refractive index of the dispersion liquid is 1.343-1.472, and the dispersion liquid has a positive Zeta potential under the condition of pH≤7 value, the content of nano-zirconia in the dispersion liquid is 5-60 wt%.

As a preferred embodiment, the dispersion liquid has a Zeta potential value in the range of 0-60mv under the condition of pH≤7. It can be understood that the test method for the Zeta potential value in this embodiment is as follows: firstly, the obtained nano-zirconia powder is added to deionized water, mixed to prepare a 5-60 wt% aqueous dispersion, and then mixed with hydrogen. The pH value was adjusted by potassium oxide. Among them, the Zeta potential value was measured in the pH range of 2-7. It can be understood that the content of nano-zirconia in the dispersion liquid can also be 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 wt % or any value within the above range.

As a preferred embodiment, the dispersion liquid is obtained by concentrating and washing the reaction solution obtained in the preparation process of the nano-zirconia powder preparation method described in the above embodiment to remove the organic acid or its salt, or by applying the above The nano-zirconia powder prepared by the method is dispersed in water.

An embodiment of the present application further provides an optical film, which is prepared by using the dispersion liquid containing the nano-zirconia powder described in any of the above embodiments. For example, an optical film can be produced by applying and drying the dispersion liquid on a transparent substrate by a wet coating method. It can be understood that the optical films provided in this embodiment can mainly be brightness enhancement films, anti-reflection films, and other optical films with high-refractive coatings.

The present application will be described in detail below with reference to the embodiments. It should be understood that these embodiments are only some preferred embodiments of the present application, and should not be construed as limiting the protection scope of the present application.

Example 1

Weigh 1.47kg zirconium oxychloride octahydrate and 138g yttrium chloride hexahydrate and dissolve in 8kg water to obtain its mixed solution A;

Dissolve 421g of sodium hydroxide in 6kg of water to obtain sodium hydroxide solution B;

After the solution A and the solution B are fully mixed under stirring, a precipitate is formed, and the precursor C is obtained after the precipitate is washed and suction filtered for many times;

Add water and 270 g of acetic acid to the precursor C (the amount of acetic acid is equal to 90% of the sum of the amount of zirconium element and stable element, that is, the molar concentration of acetic acid is 90% of the sum of the molar concentration of zirconium and stable element), control The total volume is 8L, stirring and pulping;

The slurry obtained above was put into a 10L reactor, and hydrothermally reacted at 200°C for 3h;

After the reaction is completed, the reaction solution is directly dried to obtain nano-zirconia powder.

The obtained nano-zirconia powder has a particle size of 3-10 nm and a specific surface area of 220 m ² /g, and the nano-zirconia powder includes zirconia with a tetragonal crystal structure and zirconia with a tetragonal crystal structure. The proportion accounts for more than 90% of the powder, as shown in Figure 1-3. It can be seen from Figure 1a and Figure 1b that the particle size of the obtained nano-zirconia powder is 3-10nm. It can be seen from Figure 2 that the diffraction peaks of the nano-zirconia powder above and the XRD characteristic peaks of the standard tetragonal phase grains below are Correspondingly, and the proportion of tetragonal crystal structure is relatively high. By analyzing and calculating the diffraction intensity data, it can be found that the proportion of the tetragonal crystal structure is more than 90%.

Example 2

Weigh 1.47kg of zirconium oxychloride and 69g of yttrium chloride and dissolve in 8kg of water to obtain its mixed solution A;

550g sodium hydroxide is dissolved in 6kg water to obtain potassium hydroxide solution B;

Add water and 160g acetic acid (the molar concentration of acetic acid is 56% of the sum of the molar concentration of zirconium element and stable element) to the former body C, control the total volume at 8L, and stir to make slurry;

The above obtained slurry was put into a 10L reactor, and hydrothermally reacted at 180°C for 4h;

The obtained nano-zirconia powder has a particle size of 3-10 nm, a specific surface area of 200 m ² /g, and the nano-zirconia powder includes zirconia with a tetragonal crystal structure, and zirconia with a tetragonal crystal structure. The proportion accounts for about 75% of the powder.

Example 3

Weigh 1.47kg of zirconium oxychloride and 160g of yttrium chloride and dissolve in 8kg of water to obtain its mixed solution A;

Dissolve 460g of sodium hydroxide in 6kg of water to obtain sodium hydroxide solution B;

Add water and 337g propionic acid to the former body C (the moles of propionic acid are 90% of the total moles of zirconium and stabilizing elements), control the total volume at 8L, and stir to make a slurry;

The slurry obtained above was put into a 10L reactor, and hydrothermally reacted at 220°C for 3h;

The particle size of the obtained nano-zirconia powder is 3-10 nm, and the specific surface area is 210 m ² /g, and the nano-zirconia powder includes zirconia with tetragonal crystal structure and zirconia with tetragonal crystal structure. The proportion accounts for about 83% of the powder.

Example 4

The reaction solution after the hydrothermal reaction in Example 1 is concentrated and washed for at least 3 times, and the organic acid or its salt is removed to obtain an aqueous dispersion of zirconia with a concentration of 5 wt%, that is, an aqueous dispersion of nano-zirconia.

The concentration of nano-zirconia in the obtained aqueous dispersion is 5wt%, the refractive index is 1.343, and the obtained dispersion has a Zeta potential value of 55mv under the condition of pH=3.

Example 5

The method for preparing the aqueous dispersion of nano-zirconia is the same as that in Example 4, except that the reaction solution after the hydrothermal reaction in Example 2 is used.

The concentration of nano-zirconia in the obtained aqueous dispersion is 30wt%, the refractive index is 1.386, and the obtained dispersion has a Zeta potential value of 34mv under the condition of pH=5.

Example 6

The method for preparing the aqueous dispersion of nano-zirconia is the same as that in Example 4, except that the reaction solution after the hydrothermal reaction in Example 3 is used.

The concentration of nano-zirconia in the obtained aqueous dispersion is 60wt%, the refractive index is 1.472, and the obtained dispersion has a Zeta potential value of 25mv at pH=4.

Comparative Example 1

Weigh 1.47kg of zirconium oxychloride and 138g of yttrium chloride and dissolve in 8kg of water to obtain its mixed solution A;

Add water to the front body C and stir to make a slurry;

The slurry obtained above was put into a 10L reactor, 270g of acetic acid was added, the total volume was controlled at 8L, and the hydrothermal reaction was carried out at 200°C for 3h;

As shown in FIG. 4 , the obtained nano-zirconia powder has a particle size of about 30 nm and a specific surface area of 180 m ² /g, and the nano-zirconia powder includes zirconia with a tetragonal crystal structure.

Comparative Example 2

Add water and 270g acetic acid to the front body C, control the total volume at 8L, and stir to make pulp;

The above obtained slurry was put into a 10L reactor, and hydrothermally reacted at 170°C for 3h;

The obtained nano-zirconia powder had an average particle size of 30 nm and a specific surface area of 177 m ² /g, and the nano-zirconia powder was zirconia with a monoclinic crystal structure.

Comparative Example 3

The method for preparing the aqueous dispersion of nano-zirconia is the same as that in Example 4, except that the reaction solution after the hydrothermal reaction in Comparative Example 1 is used.

The concentration of nano-zirconia in the obtained aqueous dispersion is 5wt%, and its refractive index is relatively low as 1.334. The obtained dispersion has a Zeta potential value of 46mv under the condition of pH=3.

Comparative Example 4

The concentration of nano-zirconia in the obtained aqueous dispersion liquid is 30%, and its refractive index is relatively low as 1.372, and under the condition of pH=3, the Zeta potential value of the obtained dispersion liquid is 36mv;

Comparative Example 5

The method for preparing the aqueous dispersion of nano-zirconia is the same as that in Example 4, except that the reaction solution after the hydrothermal reaction in Comparative Example 1 is adopted.

The concentration of nano-zirconia in the obtained aqueous dispersion is 60wt%, and its refractive index is relatively low as 1.455, and under the condition of pH=5, the Zeta potential value of the obtained dispersion is 23mv;

Comparative Example 6

The method for preparing the aqueous dispersion of nano-zirconia is the same as that in Example 4, except that the reaction solution after the hydrothermal reaction in Comparative Example 2 is adopted.

The concentration of nano-zirconia in the obtained aqueous dispersion is 60wt%, and its refractive index is relatively low as 1.451. The obtained dispersion has a Zeta potential value of 21mv under the condition of pH=5.

Table 1 below shows the crystal form, particle size, refractive index and Zeta potential value of the nano-zirconia powder used in the dispersions of Examples 4-6 and Comparative Examples 3-5 of the present application.

Table 1

It can be seen from the above that under the same condition of 5wt%, the refractive index of Example 4 is 1.343, and the refractive index of Comparative Example 3 is 1.334, a difference of 0.009; under the same condition of 30wt%, the refractive index of Example 5 is 1.386, and the refractive index of Comparative Example 4 is 1.386. The refractive index is 1.372, with a difference of 0.014; under the same condition of 60wt%, the refractive index of Example 6 is 1.472, the refractive index of Comparative Example 5 is 1.455, the difference is 0.017, and the refractive index of Comparative Example 6 is 1.451, and the difference is 0.021. This is because the particle size of the zirconia in the dispersion liquid in the comparative example is relatively large (Comparative Examples 3, 4, 5), and the crystal form is a monoclinic phase (Comparative Example 6), so that the prepared dispersion liquid has a relatively low refractive index. In addition, although the refractive index is not much different numerically (0.009-0.021), from the perspective of the optical properties of the refractive index of the dispersion liquid, the difference is huge. For example, using the dispersion liquid with a refractive index difference of 0.01 to prepare brightness enhancement films Applied to the display screen, its transmittance is 89% and 93%, and this is the difference between the A-level screen and the B-level screen.

Claims

The nano-zirconia powder is characterized in that the particle size of the nano-zirconia powder is 3-10 nm, the specific surface area is 200-240 m 2 /g, and the nano-zirconia powder comprises a tetragonal crystal structure of oxide Zirconium, and the proportion of zirconia with tetragonal crystal structure accounts for 60-95% of the powder.
The preparation method of nano-zirconia powder according to claim 1, is characterized in that, comprises the following steps:

Dissolving zirconium salt and stable element salt together in water to obtain solution A;

The base is dissolved in water to obtain solution B;

The solution A and the solution B are fully mixed under stirring to form a precipitate, wherein the mass of the precipitate accounts for 1-40% of the mass of the total mixed solution; after the precipitate is washed and filtered for many times, the precursor C is obtained;

Add water and organic acid or its salt to the former body C to make pulp, and the total solid content in the obtained pulp is 6-20wt%;

The above obtained slurry is put into a reaction kettle, the filling amount is 60-90%, and the hydrothermal reaction is carried out at 180°C-220°C for 1-12 hours, and a reaction solution is obtained after the reaction;

The reaction solution is directly dried or concentrated, washed and then dried to obtain nano-zirconia powder.
The preparation method according to claim 2, wherein the added zirconium salt is a water-soluble zirconium salt selected from the group consisting of basic carbonate, carbonate, nitrate, acetate, chloride, oxychloride At least one of; the added stabilizing element salt is a chloride or nitrate of a stabilizing element, wherein the stabilizing element is selected from at least one of aluminum, magnesium, titanium and rare earth elements; the alkali At least one selected from ammonia water, sodium hydroxide, potassium hydroxide and lithium hydroxide.
The preparation method according to claim 3, wherein the added zirconium salt concentration is less than or equal to 2 mol/L, the molar concentration ratio of the added stabilizing element to the zirconium element is 2/98 to 30/70, and the added The concentration of alkali is ≤8mol/L.
The preparation method according to claim 2, wherein the organic acid is selected from at least one of monocarboxylic acid, polycarboxylic acid and hydroxycarboxylic acid, wherein the monocarboxylic acid is selected from formic acid, acetic acid, At least one of propionic acid and butyric acid, polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, phthalic acid, hydroxycarboxylic acid is selected from lactic acid, malic acid, tartaric acid, citric acid At least one of the organic acids; the salts of the organic acids are alkali metal salts, selected from at least one of potassium salts and sodium salts.
The preparation method according to claim 5, wherein the molar concentration of the added organic acid or its salt is 10-100% of the total molar concentration of zirconium element and stable element.
The preparation method according to claim 2, wherein when the boiling point of the added organic acid is less than 150°C, the reaction solution is directly dried to obtain nano-zirconia powder; when the boiling point of the added organic acid is greater than 150°C, The reaction solution is concentrated and washed for several times and then dried to obtain nano-zirconia powder.
The preparation method according to claim 7, wherein the drying method is selected from any one of vacuum low-temperature drying, drying and spraying, and the concentration washing method is selected from ultrafiltration, rotary evaporation and ceramic membrane concentration Any of the washings.
The dispersion liquid comprising the nano-zirconia powder according to claim 1 is characterized in that, the refractive index of the dispersion liquid is 1.343-1.472, and it has a positive Zeta potential value under the condition of pH≤7, and the dispersion liquid has a positive Zeta potential value. The content of nano-zirconia is 5-60wt%.
The dispersion liquid according to claim 9, characterized in that, under the condition of pH≤7, the Zeta potential value of the dispersion liquid ranges from 0 to 60 mv.
The dispersion liquid according to claim 9 or 10, wherein the dispersion liquid is obtained by concentrating and washing the reaction solution obtained in the preparation process of claim 2 to remove the organic acid or its salt, or by It is obtained by dispersing the nano-zirconia powder prepared in claim 2 in water.
The optical film is characterized in that, it is prepared by using the dispersion liquid containing nano-zirconia powder according to any one of claims 9-11.
Application of the nano zirconia powder according to claim 1 or the dispersion liquid containing the nano zirconia powder according to any one of claims 9-11 in the preparation of optical films.