Nanocrystalline zirconium oxide dispersions, methods of making the same, and resulting monomer dispersions and optical films

Abstract

A nano-zirconia dispersion, its preparation method, the resulting monomer dispersion, and an optical film belong to the field of fine chemicals. The nano-zirconia dispersion contains 45-75 wt% nano-zirconia particles with a refractive index of 1.420-1.565. Infrared spectroscopy characterization revealed that the nano-zirconia particles have functional groups grafted onto their surface with the following peak range: hydroxyl groups: 3200 cm⁻¹. ‑1 -3600cm ‑1 Zr-O-Zr: 480cm ‑1 -850cm ‑1 Saturated carbon-hydrogen bonds: 2850 cm ‑1 -2960cm ‑1 Ester carbonyl group: 1700cm ‑1 -1750cm ‑1 Delocalized conjugated ester groups: 1460cm ‑1 -1580cm ‑1 Si-O-Zr: 800cm ‑1 -1200cm ‑1 C-O ether bond: 1000cm ‑1 -1200cm ‑1 This nano-zirconia dispersion has a high dispersion content, with the obtained nano-zirconia monomer dispersion reaching 55-85 wt% and a refractive index of 1.620-1.720. It can significantly increase the refractive index of high-refractive coatings in subsequent processes such as the preparation of brightness enhancement films or anti-reflection films, thereby improving the performance of the film.

Description

[0001] This application claims priority to Chinese Patent Application No. 202111067304.6, filed on September 13, 2021, entitled “Nano Zirconia Dispersion, Preparation Method Thereof, and Obtained Monomer Dispersion and Optical Film”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of fine chemicals, and in particular relates to a nano-zirconia dispersion, its preparation method, and the resulting monomer dispersion and optical film. Background Technology

[0003] In recent years, zirconia particle dispersions have been successfully combined with transparent resins or thin films, leveraging their high refractive index for excellent applications in the optical field. For example, high-refractive-index zirconia dispersions have been used to prepare optical films such as brightness enhancement films and anti-reflective films, which can be used in LCD displays to increase screen brightness and clarity; they can also be used to increase the refractive index of LED sealing resins, thereby improving LED brightness. In short, its high refractive index properties can be used in high-refractive-index coatings, finding applications in various fields.

[0004] Previously, as described above, zirconia particle dispersions used water as the dispersion medium. In many optical material applications, such as the preparation of optical thin films, aqueous dispersions are typically mixed with resin components. However, because aqueous dispersions are particularly difficult to knead with non-water-soluble resin components, there has been a strong demand in recent years for dispersions using organic solvents as the dispersion medium. Zirconia particles generally exhibit good dispersibility in aqueous solvents, but their dispersibility is typically lower compared to organic solvents.

[0005] The performance of zirconia dispersions is closely related to the crystal structure, particle dispersion state, and dispersion preparation process of the nano-zirconia in the system. CN107001066B discloses a method for preparing highly dispersed nano-zirconia particles and their transparent dispersion. This method involves directly preparing zirconia particles by reacting zirconium salt with an alkali at 170°C. Then, the water in the dispersion medium of the aqueous dispersion of zirconia particles is replaced with at least one alcohol solvent selected from methanol and ethanol. The zirconia particles in the alcohol dispersion are then surface-treated with a silane coupling agent and a 12-hydroxystearic acid surface treatment agent. Finally, the alcohol solvent in the alcohol dispersion of the zirconia particles is replaced with the target organic solvent by distillation displacement or ultrafiltration concentration displacement. The zirconia dispersion prepared by this method has a transmittance of over 10% at a wavelength of 400 nm and over 80% at a wavelength of 800 nm. At 25°C, the viscosity immediately after preparation is below 10 mPa·s. However, this process requires an alcohol solvent as an intermediate phase to obtain the target phase dispersion. The preparation process is relatively complex and costly. In addition, the alcohol solvent has a low boiling point, which limits the modification temperature and can lead to insufficient modification.

[0006] Therefore, it is particularly important to prepare a stable, uniformly dispersed zirconia dispersion with a high refractive index to better meet the performance requirements of transparent organic-inorganic composites. Summary of the Invention

[0007] This application provides a nano-zirconia dispersion, its preparation method, the resulting monomer dispersion, and an optical film. The obtained nano-zirconia dispersion has the characteristics of good dispersion uniformity and high refractive index.

[0008] To achieve the above objectives, this application adopts the following technical solution:

[0009] The first aspect of this application provides a nano-zirconia dispersion, wherein the amount of nano-zirconia particles contained in the nano-zirconia dispersion is 45-75 wt%, and the refractive index of the nano-zirconia dispersion is 1.420-1.565; wherein, infrared spectroscopy characterization reveals that the nano-zirconia particles have functional groups grafted onto their surface with the following peak ranges:

[0010] Hydroxyl group: 3200cm -1 -3600cm -1 Zr-O-Zr: 480cm -1 -850cm -1 Saturated carbon-hydrogen bonds: 2850 cm -1 -2960cm -1 Ester carbonyl group: 1700cm -1 -1750cm -1 Delocalized conjugated ester groups: 1460cm-1 -1580cm -1 Si-O-Zr: 800cm -1 -1200cm -1 ether bond with CO: 1000cm -1 -1200cm -1 .

[0011] In some embodiments of this application, the refractive index of the nano-zirconia dispersion is 1.420-1.535 when the zirconia content is 45%-65%, and 1.498-1.565 when the zirconia content is 65%-75%.

[0012] In some embodiments of this application, the refractive index of the zirconia nanoparticles in the zirconia nano dispersion is 2.20-2.60, and the proportion of tetragonal phase grain structure in the zirconia nanoparticles is 60-95%.

[0013] A second aspect of this application provides a method for preparing the nano-zirconia dispersion as described above, comprising the following steps:

[0014] An organic solvent was added to an aqueous solution of zirconium oxide, and after mixing evenly, an organic acid and a modifier were added to the system to modify the zirconium oxide particles. Then, an oily dispersing agent was added, and water was removed by rotary evaporation to obtain a nano-zirconia dispersion.

[0015] The organic acid added is 3-20 wt% of the nano-zirconia content; the modifier added is 5-20 wt% of the nano-zirconia content; and the oily dispersant added is 5-20 wt% of the nano-zirconia content.

[0016] In some embodiments of this application, the modification of zirconium oxide particles by adding organic acids and modifiers to the system specifically involves:

[0017] Under normal pressure and 50-150℃ conditions, organic acids and modifiers are added to the system to modify zirconium oxide particles; or

[0018] The organic acid and modifier are dissolved in the organic solvent and added to a dispersion of zirconium oxide aqueous solution and organic solvent under normal pressure and 50-150℃ to modify the zirconium oxide particles.

[0019] In some embodiments of this application, the organic solvent is at least one of methyl ethyl ketone, methyl isobutyl ketone, propylene glycol methyl ether, and ethylene glycol methyl ether; the volume ratio of the added organic solvent to the zirconium oxide aqueous solution is (3-5):1.

[0020] In some embodiments of this application, the organic acid is selected from at least one of saturated or unsaturated monocarboxylic acids, polycarboxylic acids, and hydroxycarboxylic acids.

[0021] In some embodiments of this application, the monocarboxylic acid is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, isooctanoic acid, acrylic acid, and methacrylic acid; the polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, phthalic acid, fumaric acid, and maleic acid; and the hydroxycarboxylic acid is selected from at least one of lactic acid, malic acid, tartaric acid, and citric acid.

[0022] In some embodiments of this application, the modifier is at least one of 3-(methacryloyloxy)propyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane.

[0023] In some embodiments of this application, the oily dispersant is selected from at least one of anionic dispersants, cationic dispersants, nonionic dispersants, and polymeric dispersants.

[0024] In some embodiments of this application, the oily dispersant is selected from BYK-9076 or BYK-9077.

[0025] A third aspect of this application provides a nano-zirconia monomer dispersion, which is prepared by adding a photocurable resin to a nano-zirconia dispersion as described in any of the preceding claims, and removing the organic solvent from the dispersion by vacuum distillation.

[0026] In some embodiments of this application, the content of nano-zirconia in the nano-zirconia monomer dispersion is 55-85 wt%, and the refractive index of the nano-zirconia monomer dispersion is 1.620-1.720.

[0027] In some embodiments of this application, the photocurable resin is selected from acrylic or methacrylic monomers or oligomers thereof containing esters, urethane, ethers, silicon, halogens and / or phosphorus-containing groups; the amount of photocurable resin added is 15-45 wt% of the total mass of zirconium oxide and photocurable resin.

[0028] In some embodiments of this application, the photocurable resin is at least one of phenoxybenzyl acrylate, methyl acrylate, and methyl methacrylate.

[0029] A fourth aspect of this application provides an optical film prepared using a nano-zirconia dispersion as described in any of the preceding claims or a nano-zirconia monomer dispersion as described in any of the preceding claims.

[0030] Compared with the prior art, the advantages and positive effects of this application are as follows:

[0031] 1. The preparation method of nano-zirconia dispersion provided in at least one embodiment of this application is simple to operate. The simplest distillation displacement method can be used to directly obtain an organic solvent dispersion from the zirconium oxide aqueous dispersion, and then the organic solvent dispersion can be used to replace the monomer dispersion, without the participation of an intermediate phase.

[0032] 2. The method for preparing nano-zirconia dispersion provided in at least one embodiment of this application uses organic acid, modifier and oily dispersant to act on zirconia particles simultaneously, making full use of their synergistic effect to achieve the best dispersion effect, which can effectively improve the compatibility of subsequent organic solvent dispersion and photocurable monomer.

[0033] 3. In the preparation method of the nano-zirconia dispersion provided in at least one embodiment of this application, organic acid and modifier need to be added to the dispersion system before adding oily dispersing agent when adding raw material components, so as to ensure that there are sufficient active sites on the zirconia surface for organic acid and modifier to act, so as to achieve the best modification and dispersion effect.

[0034] 4. In the preparation method of the nano-zirconia dispersion provided in at least one embodiment of this application, the content of the added organic acid, modifier, and oily dispersant should be controlled within the range defined in this application. If the content is too low, the expected modification effect will not be achieved, and if the content is too high, the effect will be counterproductive and unnecessary economic losses will be caused.

[0035] 5. The nano-zirconia dispersion provided in at least one embodiment of this application has a high dispersion content of nano-zirconia particles, reaching 45-75 wt%, and a refractive index of 1.420-1.565. The nano-zirconia monomer dispersion obtained based thereon has a dispersion content of 55-85 wt% and a refractive index of 1.620-1.720. Attached Figure Description

[0036] Figure 1 The infrared spectrum of the nano-zirconia dispersion provided in Example 1 of this application;

[0037] Figure 2 The infrared spectrum of the nano-zirconia dispersion provided in Example 5 of this application;

[0038] Figure 3 The infrared spectrum of the nano-zirconia dispersion provided in Example 6 of this application;

[0039] Figure 4 The infrared spectrum of the nano-zirconia dispersion provided in Example 7 of this application;

[0040] Figure 5The infrared spectrum of BYK-9076 after being added to zirconium oxide (40% addition amount) in the embodiments of this application;

[0041] Figure 6 The infrared spectrum of BYK-9076 used in the embodiments of this application after being added to zirconium oxide (addition amount 5%). Detailed Implementation

[0042] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0043] In the description of this application, unless otherwise specified, all contents not explicitly stated by unit are mass contents; in order to obtain nano-zirconia dispersion, it is understood that the zirconium oxide aqueous solution mentioned in the raw materials of this application refers to nano-zirconia aqueous solution.

[0044] To achieve the above objectives, this application provides a nano-zirconia dispersion, wherein the amount of nano-zirconia particles contained in the nano-zirconia dispersion is 45-75 wt%, wherein the nano-zirconia particles are characterized by infrared spectroscopy, which reveals that their surface is grafted with functional groups in the following peak range:

[0045] Hydroxyl group: 3200cm -1 -3600cm -1 Zr-O-Zr: 480cm -1 -850cm -1 Saturated carbon-hydrogen bonds: 2850 cm -1 -2960cm -1 Ester carbonyl group: 1700cm -1 -1750cm -1 Delocalized conjugated ester groups: 1460cm -1 -1580cm -1 Si-O-Zr: 800cm -1 -1200cm -1 ether bond with CO: 1000cm -1 -1200cm -1 Understandably, the successful introduction of these functional groups can significantly improve the lipophilicity of zirconia particles, making it possible to prepare various types of dispersions and their films. At the same time, it can have a positive impact on improving the solid content and refractive index of solvent-based and monomer-based dispersions.

[0046] In some embodiments, the refractive index of the nano-zirconia dispersion is 1.420-1.535 when the zirconia content is 45%-65%, and 1.498-1.565 when the zirconia content is 65%-75%.

[0047] In some embodiments, the refractive index of the zirconia nanoparticles in the zirconia nano dispersion is 2.20-2.60.

[0048] In some embodiments, the proportion of tetragonal phase grain structure in the nano-zirconia particles is 60-95%. It is understood that zirconia crystal forms are divided into monoclinic, tetragonal, and cubic phases. The nano-zirconia particles with tetragonal phase crystal form in the nano-zirconia dispersion of this application embodiment represent the mass percentage of all zirconia crystal forms.

[0049] This application also provides a method for preparing a nano-zirconia dispersion, comprising the following steps:

[0050] An organic solvent was added to an aqueous solution of zirconium oxide, and after mixing evenly, an organic acid and a modifier were added to the system to modify the zirconium oxide particles. Then, an oily dispersing agent was added, and water was removed by rotary evaporation to obtain a nano-zirconia dispersion.

[0051] The method for preparing nano-zirconia dispersions provided in the above embodiments involves adding organic acids and modifiers to a dispersion of zirconia particles mixed with water and an organic solvent to perform lipophilic modification treatment. While removing water, a pure organic solvent phase zirconia dispersion is obtained. Adding an oily dispersing agent further enhances the stability and dispersibility of the dispersion. This method requires no complex operations or dispersion equipment and is simple. Compared to existing technologies that replace the dispersion medium, this approach offers significant advantages.

[0052] In some embodiments, the modification of zirconium oxide particles by adding organic acids and modifiers to the system specifically involves:

[0053] Under normal pressure and 50-150℃ conditions, organic acids and modifiers are added to the system to modify zirconium oxide particles; or

[0054] The organic acid and modifier are dissolved in the organic solvent and added to a dispersion of zirconium oxide aqueous solution and organic solvent under normal pressure and 50-150℃ to modify the zirconium oxide particles.

[0055] In some embodiments, the volume ratio of the added organic solvent to the zirconium oxide aqueous solution is (3-5):1.

[0056] In some embodiments, the organic solvent is at least one selected from butanone, methyl isobutyl ketone, propylene glycol methyl ether, and ethylene glycol methyl ether.

[0057] In some embodiments, the organic acid is selected from at least one of saturated or unsaturated monocarboxylic acids, polycarboxylic acids, and hydroxycarboxylic acids; the added organic acid is 3-20 wt% of the nano-zirconia content.

[0058] In some embodiments, the monocarboxylic acid is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, isooctanoic acid, acrylic acid, and methacrylic acid; the polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, phthalic acid, fumaric acid, and maleic acid; and the hydroxycarboxylic acid is selected from at least one of lactic acid, malic acid, tartaric acid, and citric acid.

[0059] In some embodiments, the modifier is at least one of 3-(methacryloyloxy)propyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane; the added modifier is 5-20 wt% of the nano-zirconia content.

[0060] The purpose of adding organic acids and modifiers in the preparation method of the nano-zirconia dispersion provided in this application is to treat the surface of zirconia. On the one hand, this improves the oleophilicity of the zirconia particles, and on the other hand, it allows the zirconia particles to be uniformly dispersed, enabling the modifier to bind more fully with the zirconia. Furthermore, the presence of organic acids facilitates the hydrolysis and grafting of the modifier, while the presence of the modifier facilitates the grafting of organic acids and zirconia; the two promote each other. The oily dispersing agent also plays a positive role in enhancing the grafting of organic acids and modifiers with zirconia. It is understood that the amount of organic acid added can also be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 wt% of the nano-zirconia content, or any value within the above range; the amount of modifier added can also be 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 wt% of the nano-zirconia content, or any value within the above range.

[0061] In some embodiments, the oily dispersant is selected from at least one of anionic dispersants, cationic dispersants, nonionic dispersants, and polymeric dispersants, preferably phosphate ester series dispersants; the added oily dispersant is 5-20 wt% of nano-zirconia content.

[0062] It is understandable that the purpose of adding the oily dispersant in the above steps is to further improve the stability and dispersibility of the dispersion. It should be specifically noted that the oily dispersant should be added after the organic acid and modifier have been added to the dispersion system. This is to ensure that the surface of the zirconia particles has sufficient active sites for surface treatment by the organic acid and modifier. The amount of the oily dispersant added can also be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19 wt% of the nano-zirconia content, or any value within the above range.

[0063] In some embodiments, the oily dispersant may specifically be BYK-9076 and BYK-9077, manufactured by BYK GmbH, Germany.

[0064] In the above embodiments, BYK-9076 is a high molecular weight copolymer silyl ammonium salt. Figure 5 Infrared spectrum of zirconium oxide after adding BYK-9076 (40%), where 3392 cm⁻¹ -2 The hydroxyl peak at 2926 cm⁻¹ corresponds to the remaining hydroxyl groups on the zirconium oxide surface. -2 The peak at 1633 cm⁻¹ is the saturated hydrocarbon peak of BYK 9076. -2 The water peak adsorbed by zirconium oxide inorganic powder is at 1060 cm⁻¹. -2 Si-O-Zr grafted from BYK9076 and zirconium oxide, 565 cm⁻¹ -2 It is a zirconium oxide Zr-O-Zr. Figure 5 The presence of Si-O-Zr peaks in the product indicates that BYK-9076 can be grafted with zirconium oxide to form Si-O-Zr functional groups; Figure 6 Infrared spectrum of zirconium oxide after addition of BYK-9076 (5%). Figure 5 and Figure 6 It is known that Si-O-Zr peaks will appear whenever BYK9076 is added, regardless of the amount added. BYK9077 is a high molecular weight copolymer with pigment-affinity groups. Therefore, when BYK-9076 is used as an oily dispersant, it can work with the modifier to provide Si-O-Zr functional groups, further increasing the number of Si-O-Zr functional groups in the prepared nano-zirconia dispersion and improving the refractive index of the nano-zirconia dispersion. BYK9077 has a similar structure to BYK9076, but its steric hindrance is greater, and the grafting amount with zirconia is less. Therefore, hydroxyl peaks, water peaks, and Zr-O-Zr of zirconia can be seen in its infrared spectrum.

[0065] This application also provides a nano-zirconia monomer dispersion, which is prepared by adding a photocurable resin to the nano-zirconia dispersion according to any of the above technical solutions, and removing the organic solvent from the dispersion by vacuum distillation. It should be noted here that the monomer dispersion described in this application refers to a dispersion with a single component added, and not specifically to the monomer or its oligomer contained in the photocurable component.

[0066] In some embodiments, the content of nano-zirconia in the nano-zirconia monomer dispersion is 55-85 wt%, and the refractive index of the nano-zirconia monomer dispersion is 1.620-1.720. It is understood that the content of nano-zirconia in the monomer dispersion can also be 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 wt% or any value within the above range.

[0067] In some embodiments, the photocurable resin is selected from acrylic or methacrylic monomers or oligomers thereof that contain esters, urethane, ethers, silicon, halogens, and / or phosphorus-containing groups. Furthermore, the monomers or oligomers thereof are commercially available.

[0068] In some embodiments, the amount of photocurable resin added is 15-45 wt% of the total mass of zirconium oxide and photocurable resin. It is understood that the content of photocurable resin can also be 20, 25, 30, 35 wt% or any value within the above range.

[0069] In some embodiments, the photocurable resin is at least one of phenoxybenzyl acrylate, methyl acrylate, and methyl methacrylate.

[0070] This application also provides an optical film, characterized in that it is prepared using a nano-zirconia dispersion prepared by the preparation method according to any of the above technical solutions or using a nano-zirconia monomer dispersion according to any of the above technical solutions.

[0071] In some embodiments, the optical film is any one of a brightness enhancement film, an anti-reflective film, and other optical films with a high refractive coating.

[0072] To provide a clearer and more detailed description of the nano-zirconia dispersion, its preparation method, and the resulting monomer dispersion provided in the embodiments of this application, the following description will be based on specific embodiments.

[0073] Example 1

[0074] Propylene glycol methyl ether (PGME) solvent was added to an aqueous solution of zirconium oxide and mixed thoroughly. Then, isooctanoic acid (5% of the zirconium content) and 3-(methacryloyloxy)propyltrimethoxysilane (10% of the zirconium content) were added sequentially to the system to modify the zirconium oxide particles. Then, oily dispersant BYK-9076 (5% of the amount added) was added, and water was removed by rotary evaporation to obtain a nano-zirconia organic PGME dispersion.

[0075] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.475 when the concentration of nano-zirconia is 45wt%, the refractive index is 1.535 when the concentration is 65%, and the refractive index is 1.565 when the concentration is 75wt%.

[0076] Appendix Figure 1 The infrared spectrum of Example 1 is shown, where 3418 cm⁻¹ -1 The absorption peak is a characteristic absorption peak of hydroxyl groups on the surface of zirconia particles, at 589 cm⁻¹. -1 496cm -1 The characteristic absorption peak of Zr-O-Zr is observed at 2950 cm⁻¹. -1 The characteristic peak of saturated carbon-hydrogen bonds is 1718 cm⁻¹. -1 The characteristic peak of the ester carbonyl group is 1561 cm⁻¹. -1 1463cm -1 The characteristic absorption peak for delocalized conjugated ester groups is 1170 cm⁻¹. -1 The characteristic absorption peak of Si-O-Zr is 1025 cm⁻¹. -1 The characteristic absorption peaks for CO ether bonds indicate that isooctanoic acid and 3-(methacryloyloxy)propyltrimethoxysilane have been successfully grafted onto the surface of zirconium oxide particles.

[0077] Example 2

[0078] The preparation method is the same as in Example 1, except that the amount of isooctanoic acid added is 3% of the zirconium content, the amount of 3-glycidyl etheroxypropyltrimethoxysilane is 5% of the zirconium content, and the amount of oily dispersant BYK-9076 is 10% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0079] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.470 when the concentration of nano-zirconia is 45wt%, 1.529 when the concentration is 65%, and 1.558 when the concentration is 75wt%.

[0080] Example 3

[0081] The preparation method is the same as in Example 1, except that the amount of isooctanoic acid added is 12% of the zirconium content, the amount of modifier 3-(methacryloyloxy)propyltrimethoxysilane is 15% of the zirconium content, and the amount of oily dispersant BYK-9077 is 15% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0082] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.461 when the concentration of nano-zirconia is 45wt%, 1.522 when the concentration is 65%, and 1.552 when the concentration is 75wt%.

[0083] Example 4

[0084] The preparation method is the same as in Example 1, except that the amount of isooctanoic acid added is 20% of the zirconium content, the amount of modifier 3-glycidyl etheroxypropyltrimethoxysilane is 20% of the zirconium content, and the amount of oily dispersant BYK-9077 is 20% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0085] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.449 when the concentration of nano-zirconia is 45wt%, 1.509 when the concentration is 65%, and 1.540 when the concentration is 75wt%.

[0086] Example 5

[0087] The preparation method is the same as in Example 1, except that the added organic acid is dodecyl hydroxystearic acid, and the amount of acid added is 5% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0088] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.467 when the concentration of nano-zirconia is 45wt%, 1.525 when the concentration is 65%, and 1.554 when the concentration is 75wt%.

[0089] Appendix Figure 2 The infrared spectrum of Example 5 is shown, where 3427 cm⁻¹ -1 The absorption peak is a characteristic peak of hydroxyl groups on the surface of zirconium oxide particles, at 586 cm⁻¹. -1 483cm -1 This is a characteristic absorption peak for Zr-O-Zr. Additionally, at 2925 cm⁻¹... -1 The characteristic peak of saturated carbon-hydrogen bonds is 1715 cm⁻¹. -1 The characteristic peak of the ester carbonyl group is 1562 cm⁻¹. -1 1463cm -1 The characteristic absorption peak for delocalized conjugated ester groups is 1169 cm⁻¹. -1The characteristic absorption peak of Si-O-Zr is 1032 cm⁻¹. -1 The characteristic absorption peaks for CO ether bonds indicate that dodecyl stearic acid and 3-(methacryloyloxy)propyltrimethoxysilane have been successfully grafted onto the surface of zirconium oxide particles.

[0090] Example 6

[0091] The preparation method is the same as in Example 1, except that the added organic acid is acetic acid, and the amount of acid added is 5% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0092] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.420 when the concentration of nano-zirconia is 45wt%, 1.498 when the concentration is 65%, and 1.530 when the concentration is 75wt%.

[0093] Appendix Figure 3 The infrared spectrum of Example 6 is shown, where 3427 cm⁻¹ -1 The absorption peak is a characteristic peak of hydroxyl groups on the surface of zirconia particles, at 589 cm⁻¹. -1 496cm -1 This is a characteristic absorption peak for Zr-O-Zr. Additionally, at 2934 cm⁻¹... -1 The characteristic peak of a saturated carbon-hydrogen bond is 1711 cm⁻¹. -1 The characteristic peak of the ester carbonyl group is 1558 cm⁻¹. -1 1465cm -1 The characteristic absorption peak for delocalized conjugated ester groups is 1167 cm⁻¹. -1 The characteristic absorption peak of Si-O-Zr is 1031 cm⁻¹. -1 The characteristic absorption peaks for CO ether bonds indicate that acetic acid and 3-(methacryloyloxy)propyltrimethoxysilane have been successfully grafted onto the surface of zirconium oxide particles.

[0094] Example 7

[0095] The preparation method is the same as in Example 1, except that the added organic acid is propionic acid, and the amount of acid added is 5% of the zirconium content, thus obtaining a nano-zirconia organic PGME type dispersion.

[0096] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.457 when the concentration of nano-zirconia is 45wt%, 1.513 when the concentration is 65%, and 1.548 when the concentration is 75wt%.

[0097] Appendix Figure 4 The infrared spectrum of Example 7 shows the absorption peak at 3434 cm⁻¹, which is the characteristic peak of hydroxyl groups on the surface of zirconium oxide particles, and the peak at 580 cm⁻¹. -1 490cm-1 This is a characteristic absorption peak for Zr-O-Zr. Additionally, at 2932 cm⁻¹... -1 The characteristic peak of a saturated carbon-hydrogen bond is 1714 cm⁻¹. -1 The characteristic peak of the ester carbonyl group is 1563 cm⁻¹. -1 1467cm -1 The characteristic absorption peak for delocalized conjugated ester groups is 1109 cm⁻¹. -1 The characteristic absorption peak of Si-O-Zr is 1027 cm⁻¹. -1 The characteristic absorption peaks for CO ether bonds indicate that propionic acid and 3-(methacryloyloxy)propyltrimethoxysilane have been successfully grafted onto the surface of zirconium oxide particles.

[0098] Example 8

[0099] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 1, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0100] The refractive index of the dispersion is 1.675 when the content of nano-zirconia is 55 wt%, 1.700 when the content is 75 wt%, and 1.720 when the content is 85 wt%.

[0101] Example 9

[0102] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 2, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0103] The refractive index of the dispersion is 1.660 when the content of nano-zirconia is 55 wt%, 1.687 when the content is 75 wt%, and 1.706 when the content is 85 wt%.

[0104] Example 10

[0105] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 3, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0106] The refractive index of the dispersion is 1.644 when the content of nano-zirconia is 55 wt%, 1.667 when the content is 75 wt%, and 1.687 when the content is 85 wt%.

[0107] Example 11

[0108] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 4, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0109] The refractive index of the dispersion is 1.620 when the content of nano-zirconia is 55wt%, 1.643 when the content is 75wt%, and 1.662 when the content is 85wt%.

[0110] Example 12

[0111] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 5, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0112] The refractive index of the dispersion is 1.650 when the content of nano-zirconia is 55wt%, 1.676 when the content is 75wt%, and 1.695 when the content is 85wt%.

[0113] Example 13

[0114] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 6, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0115] The refractive index of the dispersion is 1.621 when the content of nano-zirconia is 55 wt%, 1.641 when the content is 75 wt%, and 1.656 when the content is 85 wt%.

[0116] Example 14

[0117] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Example 7, and the mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0118] The refractive index of the dispersion is 1.631 when the content of nano-zirconia is 55 wt%, 1.657 when the content is 75 wt%, and 1.678 when the content is 85 wt%.

[0119] Comparative Example 1

[0120] The preparation method is the same as in Example 1, except that the content of isooctanoic acid added is 0, resulting in a nano-zirconia organic PGME type dispersion. The zirconia particles have hydroxyl groups, Zr-O-Zr, and Si-O-Zr on their surface, but lack ester carbonyl groups, CO ether bonds, conjugated ester groups, and saturated C-H bond groups.

[0121] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.395 when the concentration of nano-zirconia is 45wt%, 1.434 when the concentration is 65%, and 1.472 when the concentration is 75wt%.

[0122] Comparative Example 2

[0123] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 1. The mixture was subjected to vacuum distillation to remove the organic solvent. The final product, zirconia, precipitated out, and the nano-zirconia dispersion with photocurable phenoxybenzyl acrylate could not be obtained.

[0124] Comparative Example 3

[0125] Propylene glycol methyl ether (PGME) solvent was added to an aqueous solution of zirconium oxide and mixed thoroughly. Then, 5% of an oily dispersant, BYK-9076, was added to the system, followed by isooctanoic acid (5% of the zirconium content) and 3-(methacryloyloxy)propyltrimethoxysilane (10% of the zirconium content) to modify the zirconium oxide particles. Water was removed by rotary evaporation to obtain a nano-zirconia organic PGME dispersion. The zirconium oxide particles have hydroxyl, Zr-O-Zr, Si-O-Zr groups, conjugated ester groups, ester carbonyl groups, and CO ether groups on their surface, but lack saturated C-H bonds.

[0126] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.398 when the concentration of nano-zirconia is 45wt%, 1.445 when the concentration is 65%, and 1.484 when the concentration is 75wt%.

[0127] Comparative Example 4

[0128] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 3. The mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0129] When the content of nano-zirconia in the dispersion is 55 wt%, the refractive index is 1.575; when the content is 75 wt%, the refractive index is 1.598.

[0130] Comparative Example 5

[0131] The preparation method is the same as Comparative Example 3, except that an oily dispersant BYK-9076 (5% addition) is added to the system, followed by the addition of dodecyl hydroxystearic acid (5% of the zirconium content) and 3-(methacryloyloxy)propyltrimethoxysilane (10% of the zirconium content) to modify the zirconium oxide particles, resulting in a nano-zirconia organic PGME dispersion. The zirconium oxide particles have hydroxyl, Zr-O-Zr, Si-O-Zr groups, conjugated ester groups, ester carbonyl groups, and CO ether groups on their surface, but no saturated C-H bonds.

[0132] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.396 when the concentration of nano-zirconia is 45wt%, 1.442 when the concentration is 65%, and 1.480 when the concentration is 75wt%.

[0133] Comparative Example 6

[0134] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 5. The mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0135] When the content of nano-zirconia in the dispersion is 55 wt%, the refractive index is 1.570; when the content is 75 wt%, the refractive index is 1.594.

[0136] Comparative Example 7

[0137] The preparation method is the same as in Example 5, except that the amounts of dodecyl stearic acid, 3-(methacryloyloxy)propyltrimethoxysilane, and oily dispersant BYK-9076 added are 25% of the zirconium content, respectively, to obtain a nano-zirconia organic PGME type dispersion. The surface of the zirconium oxide particles has hydroxyl groups, Zr-O-Zr, Si-O-Zr groups, CO ether bonds, ester carbonyl groups, and saturated C-H bonds, but no conjugated ester groups.

[0138] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.398 when the concentration of nano-zirconia is 45wt%, 1.447 when the concentration is 65%, and 1.481 when the concentration is 75wt%.

[0139] Comparative Example 8

[0140] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 7. The mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0141] When the content of nano-zirconia in the dispersion is 55 wt%, the refractive index is 1.567; when the content is 75 wt%, the refractive index is 1.591.

[0142] Comparative Example 9

[0143] The preparation method is the same as in Example 1, except that the amounts of isooctanoic acid, 3-glycidyl etheroxypropyltrimethoxysilane, and oily dispersant BYK-9076 added are 30% of the zirconium content, respectively, to obtain a nano-zirconia organic PGME type dispersion. The zirconium oxide particles have hydroxyl groups, Zr-O-Zr, Si-O-Zr groups, CO ether bonds, ester carbonyl groups, and saturated C-H bonds on their surface, but no conjugated ester groups.

[0144] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.389 when the concentration of nano-zirconia is 45wt%, 1.446 when the concentration is 65%, and 1.485 when the concentration is 75wt%.

[0145] Comparative Example 10

[0146] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 9. The mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0147] When the content of nano-zirconia in the dispersion is 55 wt%, the refractive index is 1.557; when the content is 75 wt%, the refractive index is 1.582.

[0148] Comparative Example 11

[0149] The preparation method is the same as in Example 1, except that the content of 3-(methacryloyloxy)propyltrimethoxysilane added is 0, resulting in a nano-zirconia organic PGME type dispersion. The zirconia particles have hydroxyl groups, Zr-O-Zr, Si-O-Zr on their surface, but lack ester carbonyl groups, CO ether bonds, conjugated ester groups, and saturated C-H bonds.

[0150] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.399 when the concentration of nano-zirconia is 45wt%, 1.439 when the concentration is 65%, and 1.477 when the concentration is 75wt%.

[0151] Comparative Example 12

[0152] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 11. The mixture was subjected to vacuum distillation to remove the organic solvent. The final product, zirconia, precipitated out, and the nano-zirconia dispersion with photocurable phenoxybenzyl acrylate could not be obtained.

[0153] Comparative Example 13

[0154] The preparation method is the same as in Example 1, except that the added oily dispersant is DISPERBYK-111 (added at 5% of the zirconium content), resulting in a nano-zirconia organic PGME type dispersion. The zirconium oxide particles have hydroxyl groups, Zr-O-Zr, COOH, saturated C-H bond groups, ester carbonyl groups, and CO ether bonds on their surface, but lack Si-O-Zr and conjugated ester groups.

[0155] In the nano-zirconia organic PGME type dispersion, the refractive index is 1.391 when the concentration of nano-zirconia is 45wt%, 1.443 when the concentration is 65%, and 1.481 when the concentration is 75wt%.

[0156] Comparative Example 14

[0157] Phenoxybenzyl acrylate was added to the nano-zirconia organic PGME dispersion prepared in Comparative Example 13. The mixture was subjected to vacuum distillation to remove the organic solvent, thereby obtaining a photocurable phenoxybenzyl acrylate nano-zirconia dispersion.

[0158] The refractive index of the dispersion is 1.560 when the content of nano-zirconia is 55wt% and 1.587 when the content is 75wt%.

[0159] Table 1. Summary of differences and product data between Examples 1-14 and Comparative Examples 1-14

[0160]

[0161]

[0162] The following is a comparative analysis of the embodiments of this application and the comparative examples:

[0163] Without the addition of organic acid (Comparative Example 1) or modifier (Comparative Example 11), the absence of a synergistic effect between organic acid and modifier resulted in the zirconia surface of Comparative Examples 1 and 11 being solely supplied with Si-O-Zr by the oily dispersant. Consequently, the preparation of monomeric dispersions in Comparative Examples 2 and 12 failed. This demonstrates that the effects of organic acid, modifier, and oily dispersant on zirconia particles are synergistic. Variations in this synergistic effect lead to different grafting groups on the zirconia particle surface, thus affecting the successful preparation of the dispersion.

[0164] Comparative Examples 3 and 5, due to the initial addition of 5% oily dispersant BYK9076, resulted in insufficient active sites on the zirconia surface. The long-chain isooctanoic acid and dodecyl stearic acid had significant steric hindrance, making grafting with the limited active sites on the zirconia surface difficult. Therefore, Comparative Examples 3 and 5 lacked saturated hydrocarbons, and the content of nano-zirconia in their monomeric dispersions was limited to a maximum of 75 wt%, with refractive indices of 1.598 and 1.594, respectively. This is significantly lower than the refractive indices of 1.641-1.700 for 75 wt% monomeric dispersions in Examples 8-14, not to mention the higher refractive indices at 85 wt% in Examples 8-14. In Examples 1-7 of this application, when modifiers and organic acids were added first to modify the zirconia particles, the zirconia surface had sufficient active sites for the organic acids and modifiers to act, resulting in better modification and dispersion effects.

[0165] In Comparative Examples 7 and 9, the long carbon chains of dodecyl stearic acid and isooctanoic acid, which have electron-donating properties, and the relatively large amounts added (25% and 30%), directly weaken or even eliminate the electron-deficient nature of the zirconia center due to the grafting of such a large number of electron-donating groups. Therefore, no conjugated ester groups appear, resulting in a maximum content of nano-zirconia in the monomeric dispersion of only 75 wt%, and a refractive index of only 1.591 and 1.582. In the embodiments of this application, the amount of organic acid added is small and insufficient to offset the electron-deficient nature of the zirconia center, thus conjugated ester groups are present.

[0166] Unlike the oily dispersant used in Comparative Example 13, the zirconia particles in Comparative Example 13 exhibited a COOH peak on their surface and lacked Si-O-Zr and conjugated ester peaks. This indicates that the organic acid and modifier in Comparative Example 13 did not interact with zirconia through grafting but rather simply coated the zirconia surface. Consequently, the refractive indices of the solvent-based dispersions at various concentrations in Comparative Example 13 were all lower than those in Example 1. Furthermore, the content of nano-zirconia in the monomeric dispersion in Comparative Example 14 was limited to a maximum of 75 wt%, with a refractive index of 1.587, significantly lower than the 1.700 refractive index of the 75 wt% monomeric dispersion in Example 8, not to mention the higher refractive index at 85 wt% in Example 8. This demonstrates that the oily dispersant BYK9076 has a significant impact on promoting the grafting of organic acid and modifier with zirconia particles, thereby affecting the number and type of grafted groups on the zirconia particle surface and significantly increasing the refractive index of the dispersion.

[0167] Therefore, the preparation method provided in Examples 1-7 of this application utilizes the synergistic effect of organic acid, modifier and oily dispersant on zirconium oxide particles, and controls the content of each reagent within the range provided in the examples of this application, grafting the expected functional groups onto the surface of nano-zirconia particles, and finally obtaining a nano-zirconia dispersion with good dispersion uniformity and high refractive index. This nano-zirconia dispersion can significantly improve the refractive index of high refractive coatings in subsequent preparations, such as the preparation of brightening films or anti-reflective films, thereby improving the performance of the film. As can be seen from the refractive index data in Table 1, for solvent-based dispersions, under the same 75wt% condition, the refractive indices of Examples 1-7 are 1.530-1.565, while those of Comparative Examples 1, 3, 5, 7, 9, 11, and 13 are 1.472-1.485, a difference of 0.058-0.08. Although the numerical difference in refractive index is not significant, the difference is enormous from the perspective of the refractive index of the dispersion. For example, using dispersions with a refractive index difference of 0.01 to prepare brightness enhancement films for use on displays, their transmittance is 89% and 93%, respectively, which is precisely the difference between a Class B screen and a Class A screen.

Claims

1. A nano-zirconia monomer dispersion, characterized in that, It was prepared by adding a photocurable resin to a nano-zirconia dispersion and removing the organic solvent from the dispersion by vacuum distillation; The nano-zirconia dispersion contains 45-75 wt% nano-zirconia particles, and the refractive index of the nano-zirconia dispersion is 1.420-1.

565. Infrared spectroscopy characterization revealed that the nano-zirconia particles have functional groups grafted onto their surface with the following peak ranges: Hydroxyl group: 3200cm -1 -3600cm -1 Zr-O-Zr: 480cm -1 -850cm -1 Saturated carbon-hydrogen bonds: 2850 cm -1 -2960cm -1 Ester carbonyl group: 1700cm -1 -1750cm -1 Delocalized conjugated ester groups: 1460cm -1 -1580cm -1 Si-O-Zr: 800cm -1 -1200cm -1 ether bond with CO: 1000cm -1 -1200cm -1 ; The preparation method of the nano-zirconia dispersion includes the following steps: An organic solvent was added to an aqueous solution of zirconium oxide, and after mixing evenly, an organic acid and a modifier were added to the system to modify the zirconium oxide particles. Then, an oily dispersing agent was added, and water was removed by rotary evaporation to obtain a nano-zirconia dispersion. The organic acid added is 3-20 wt% of the nano-zirconia content; the modifier added is 5-20 wt% of the nano-zirconia content; and the oily dispersant added is 5-20 wt% of the nano-zirconia content. The oily dispersing agent is a high molecular weight copolymer silyl ammonium salt or a high molecular weight copolymer with pigment affinity groups. The organic acid is selected from at least one of saturated or unsaturated monocarboxylic acids, polycarboxylic acids, and hydroxycarboxylic acids. The monocarboxylic acid is selected from at least one of formic acid, acetic acid, propionic acid, butyric acid, isooctanoic acid, acrylic acid, and methacrylic acid. The polycarboxylic acid is selected from at least one of oxalic acid, malonic acid, succinic acid, phthalic acid, fumaric acid, and maleic acid. The hydroxycarboxylic acid is selected from at least one of lactic acid, malic acid, tartaric acid, and citric acid. The modifier is at least one of 3-(methacryloyloxy)propyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane.

2. The nano-zirconia monomer dispersion according to claim 1, characterized in that, The refractive index of the nano-zirconia dispersion is 1.420-1.535 when the zirconia content is 45%-65%, and 1.565, 1.558, 1.552, 1.540, 1.554, 1.530 or 1.548 when the zirconia content is 75%.

3. The nano-zirconia monomer dispersion according to claim 1, characterized in that, The refractive index of the zirconia nanoparticles in the nano-zirconia dispersion is 2.20-2.60, and the proportion of tetragonal phase grain structure in the zirconia nanoparticles is 60-95%.

4. The nano-zirconia monomer dispersion according to claim 1, characterized in that, The modification of zirconium oxide particles by adding organic acids and modifiers to the system is specifically as follows: Under normal pressure and 50-150℃ conditions, organic acids and modifiers are added to the system to modify zirconium oxide particles; or The organic acid and modifier are dissolved in the organic solvent and added to a dispersion of zirconium oxide aqueous solution and organic solvent under normal pressure and 50-150℃ to modify the zirconium oxide particles.

5. The nano-zirconia monomer dispersion according to claim 1, characterized in that, The organic solvent is at least one of methyl ethyl ketone, methyl isobutyl ketone, propylene glycol methyl ether, and ethylene glycol methyl ether; the volume ratio of the added organic solvent to the zirconium oxide aqueous solution is (3-5):

1.

6. The nano-zirconia monomer dispersion according to claim 1, characterized in that, The oily dispersant is selected from BYK-9076 or BYK-9077.

7. The nano-zirconia monomer dispersion according to any one of claims 1-6, characterized in that, The nano-zirconia monomer dispersion contains 55-85 wt% nano-zirconia and has a refractive index of 1.620-1.

720.

8. The nano-zirconia monomer dispersion according to any one of claims 1-6, characterized in that, The photocurable resin is selected from acrylic or methacrylic monomers or oligomers containing esters, ethers, silicon, halogens and / or phosphorus-containing groups; the amount of photocurable resin added is 15-45 wt% of the total mass of zirconium oxide and photocurable resin.

9. The nano-zirconia monomer dispersion according to claim 8, characterized in that, The photocurable resin is at least one of phenoxybenzyl acrylate, methyl acrylate, and methyl methacrylate.

10. An optical film, characterized in that, It was prepared using the nano-zirconia monomer dispersion according to any one of claims 1-9.

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