Aqueous titania dispersions, methods of making and using the same, and optical coatings

Abstract

The application provides a water-based titanium dioxide dispersion liquid, a preparation method and application thereof, and an optical coating, wherein the porosity of titanium dioxide particles in the water-based titanium dioxide dispersion liquid is 5-20%, and / or the refractive index of the water-based titanium dioxide dispersion liquid with a solid content of 35 wt.% is 1.5-1.7. The preparation method provided by the application can obtain a water-based titanium dioxide dispersion liquid with low porosity and high refractive index, and the porosity and refractive index of the dispersion liquid and the optical coating containing the dispersion liquid can be adjusted by regulating the types and proportions of a complexing agent, a stabilizer and a porosity reducing agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium dioxide dispersion liquid, in particular to a water-based titanium dioxide dispersion liquid, a preparation method and application thereof, and an optical coating. BACKGROUND

[0002] Refractive index and dispersion are important properties of optical materials, and inorganic materials have a wide range of applications in related industries. For example, high-refractive nanocomposites prepared by dispersing titanium dioxide (TiO2) nanoparticles in resin have been used in optical fields such as camera lenses, displays, brightening coatings, optical waveguides, anti-reflection films, and brightening films. Porosity is an important factor affecting the refractive index of particles. The presence of pores can greatly reduce the high-refractive properties of titanium oxide particles, and too high porosity can adversely affect the mechanical properties such as hardness and tensile properties of optical coatings.

[0003] In patent CN113896229A, nanometer titanium dioxide material is obtained by using a solid-liquid interface synthesis method. The preparation method of the nanometer titanium dioxide includes the following steps: first, mixing titanium oxide compound powder with a small amount of water and a catalyst; second, sealing the titanium oxide compound powder mixed with a small amount of water and a catalyst; third, heat treating the sealed titanium oxide compound powder mixed with a small amount of water and a catalyst to obtain a nanometer titanium dioxide product. Although it has certain water solubility and dispersibility, the process is complex, the refractive index is low, and it cannot meet the application in the optical field. Therefore, it is of great significance to develop a titanium dioxide microparticle with low porosity and simple process that meets the application in the optical field.

[0004] Therefore, how to simplify the production process and obtain a water-based titanium dioxide dispersion liquid with low porosity and high refractive index needs to be solved. SUMMARY

[0005] The purpose of the present application is to provide a water-based titanium dioxide dispersion liquid, a preparation method thereof, and an optical coating, so as to obtain a water-based titanium dioxide dispersion liquid with low porosity and high refractive index of titanium dioxide particles and an optical coating containing the dispersion liquid.

[0006] To achieve the above purpose, the present application provides the following technical solutions:

[0007] A water-based titanium dioxide dispersion liquid, the porosity of titanium dioxide particles in the water-based titanium dioxide dispersion liquid is 5-20%;

[0008] And / or, the refractive index of the water-based titanium dioxide dispersion liquid with a solid content of 35 wt.% is 1.5-1.7.

[0009] In some embodiments of the present application, the porosity of titanium dioxide particles in the water-based titanium dioxide dispersion liquid is 5.31-18.26%.

[0010] Preferably, the refractive index of the aqueous titanium dioxide dispersion is 1.52-1.66 at a solid content of 35 wt.%.

[0011] In some embodiments of the present application, the particle size of the titanium dioxide in the aqueous titanium dioxide dispersion is 1-50 nm.

[0012] In some embodiments of the present application, the aqueous titanium dioxide dispersion is obtained by reaction of a titanium source, a complexing agent, a stabilizer, a pore-eliminating agent and water.

[0013] In some embodiments of the present application, the titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide and titanium acetylacetonate.

[0014] In some embodiments of the present application, the complexing agent is selected from any one or a combination of at least two of methanol, ethanol, isopropyl alcohol, butanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether and benzyl alcohol.

[0015] In some embodiments of the present application, the stabilizer is selected from any one or a combination of at least two of acetic acid, hydrochloric acid, acetylacetone and triethanolamine.

[0016] In some embodiments of the present application, the pore-eliminating agent is selected from a nitrogen-containing compound and / or a polyether.

[0017] Preferably, the nitrogen-containing compound is selected from any one or a combination of at least two of trialkyl melamine, cyanuric chloride melamine and fatty amine.

[0018] Preferably, the polyether is selected from any one or a combination of at least two of an ethylene oxide and propylene oxide block copolymer, a glycerol propylene oxide copolyether.

[0019] To achieve the above object, the present application further provides the following technical solutions.

[0020] A preparation method of the aqueous titanium dioxide dispersion as described above, the preparation method comprising the following steps:

[0021] S1, mixing a titanium source, a complexing agent and a stabilizer, and then mixing the obtained mixture with water and heating to obtain a titanium dioxide precursor;

[0022] S2, mixing the titanium dioxide precursor and a pore-eliminating agent and heating to obtain a primary dispersion;

[0023] S3, centrifuging the primary dispersion liquid to remove supernatant, washing the obtained lower gel after centrifugation, and adjusting the solid content to obtain the aqueous titanium dioxide dispersion liquid.

[0024] In some embodiments of the present application, the titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium acetylacetonate.

[0025] In some embodiments of the present application, the complexing agent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, butanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, benzyl alcohol.

[0026] In some embodiments of the present application, the stabilizer is selected from any one or a combination of at least two of acetic acid, hydrochloric acid, acetylacetone, triethanolamine.

[0027] In some embodiments of the present application, the pore-eliminating agent is selected from nitrogen-containing compounds and / or polyethers.

[0028] Preferably, the nitrogen-containing compound is selected from any one or a combination of at least two of trialkyl melamine, cyanuric chloride melamine, fatty amine.

[0029] Preferably, the polyether is selected from any one or a combination of at least two of oxirane and propylene oxide block copolymer, glycerol propylene oxide copolyether.

[0030] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source and the stabilizer is 1:(0.01-1.5), preferably 1:(0.15-0.3).

[0031] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source and the complexing agent is 1:(0.1-15), preferably 1:(0.5-3).

[0032] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source and water is 1:(0.01-2), preferably 1:(0.15-0.5).

[0033] In some embodiments of the present application, in the step S1, the heating temperature is 20-150℃, preferably 50-90℃.

[0034] In some embodiments of the present application, in the step S1, the heating time is 1-30h, preferably 6-15h.

[0035] In some embodiments of the present application, in step S2, the weight ratio of the titanium dioxide precursor and the pore-eliminating agent is 1:(0.01-0.2), preferably 1:(0.01-0.1).

[0036] In some embodiments of the present application, in step S2, the titanium dioxide precursor and the pore-eliminating agent are subjected to hydrothermal reaction, and the heating temperature is 100-250 DEG C, preferably 180-250 DEG C.

[0037] And / or, in step S2, the heating duration is 1-28 h, preferably 12-24 h.

[0038] In some embodiments of the present application, the aqueous titanium dioxide dispersion obtained by the method is subjected to drying to obtain titanium dioxide particles, and the average particle size of the titanium dioxide particles is 1-50 nm.

[0039] To achieve the above object, the present application further provides the following technical solutions.

[0040] Use of the aqueous titanium dioxide dispersion as described above in the field of optics, wherein the aqueous titanium dioxide dispersion is used as an optical coating.

[0041] To achieve the above object, the present application further provides the following technical solutions.

[0042] An optical coating, wherein the optical coating contains the aqueous titanium dioxide dispersion as described above.

[0043] Compared with the prior art, the technical solutions of the present application have the following beneficial effects.

[0044] The preparation method provided by the present application can obtain an aqueous titanium dioxide dispersion with low porosity and high refractive index of titanium dioxide particles, and the porosity and refractive index of the dispersion and the optical coating containing the dispersion can be adjusted by regulating the types and proportions of the complexing agent, the stabilizer and the pore-eliminating agent.

[0045] The titanium dioxide particle preparation method adopted by the present application is simple, does not require complex process means, has low cost, and is conducive to large-scale industrial production.

[0046] The titanium dioxide particles prepared by the present application have low porosity, which is conducive to the improvement of the refractive index of the overall aqueous dispersion, and is conducive to reducing light loss when preparing an optical film or coating in the later stage, which not only can improve the optical performance of the optical film or coating, but also can improve its mechanical performance. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments description. Obviously, the drawings described below only show some of the embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0048] Figure 1 The flow chart of the preparation method provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort also belong to the protection scope of the present application. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0050] Any specific numerical value (including the endpoints of a range of numerical values) disclosed herein should be interpreted as being approximate rather than exact, and to encompass values approximately equivalent to the value recited. Furthermore, to the extent that any numerical ranges are disclosed herein, these are to be construed as having endpoints that are not inclusive of the endpoints. Any numerical range disclosed herein is intended to include all derived or substitutable numerical values falling within that range, including endpoints.

[0051] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the definitions of terms used herein and the definitions of terms used in the prior art, the definitions of terms used herein prevail.

[0052] Reference Figure 1 In some embodiments of the present application, a preparation method of an aqueous titanium dioxide dispersion liquid comprises the following steps: S1, mixing a titanium source, a complexing agent and a stabilizer, then mixing the obtained mixture with water and heating to obtain a titanium dioxide precursor; S2, mixing the titanium dioxide precursor with a pore-eliminating agent and heating to obtain a primary dispersion liquid; S3, centrifuging the primary dispersion liquid to remove supernatant, washing the obtained lower layer colloid after centrifugation, and adjusting the solid content to obtain the aqueous titanium dioxide dispersion liquid.

[0053] In some embodiments of the present application, the adjustment operation of the solid content is specifically: dissolving the washed titanium dioxide in 5 times the mass of water, dispersing for 2 hours under ultrasonic (power 360w), and removing water by using a rotary evaporator to concentrate to 35 wt.% solid content.

[0054] It is worth mentioning that the solvent of the aqueous titanium dioxide dispersion described in the present application is water, which is the reason for the definition of "aqueous"; specifically, the free substances other than the titanium dioxide particles prepared by the method provided by the present application have been removed in the step S3 described above.

[0055] In some embodiments of the present application, the washing operation for the lower layer gel described above is specifically: dissolving the lower layer gel after centrifugation in 3 times mass of ethanol, ultrasonic (power 360W) for 30 minutes, then centrifuging at 10000 rpm for 15 min, repeating three times.

[0056] In some embodiments of the present application, in the step S1, the titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, titanium acetylacetonate. It is worth mentioning that the above-mentioned organic titanium source used in the present application has the advantages of stable properties, mild reaction conditions, high yield (under the preparation method provided by the present application), high crystallinity and crystallinity of the generated precursor (under the preparation method provided by the present application), and easy adjustment of the porosity of the obtained titanium dioxide particles; in addition, it is worth mentioning that the preparation method used in the present application uses the above-mentioned specially selected titanium source, so that no additional pretreatment of the titanium source itself is required before the preparation process begins.

[0057] In some embodiments of the present application, when titanium butoxide is used as the titanium source, the surface of the titanium dioxide particles in the aqueous titanium dioxide dispersion obtained after the step S3 is grafted with n-butyl (titanium butoxide hydrolysis produces butanol, and part of the butanol is further grafted onto the surface of the above-mentioned titanium dioxide particles) and the complexing agent, and the grafting of n-butyl and the complexing agent reduces the porosity of the titanium dioxide particles.

[0058] In some embodiments of the present application, in the step S1, the complexing agent is selected from any one or a combination of at least two of methanol, ethanol, isopropyl alcohol, butanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, benzyl alcohol. It is worth mentioning that the use of the above-mentioned alcohols and ethers as the complexing agent in the present application can improve the solubility of the above-mentioned titanium source, and can adjust the rate of condensation reaction during the reaction process, ensure the uniform dispersion of the precursor, and be conducive to controlling and adjusting the porosity of the titanium dioxide particles.

[0059] In some embodiments of the present application, in the step S1, the stabilizer is selected from any one or a combination of at least two of acetic acid, hydrochloric acid, acetylacetone, and triethanolamine. It is worth mentioning that the use of the above-mentioned substances as the stabilizer in the present application can stabilize the hydrolysis rate, reduce the generation of titanium dioxide impurities, improve the dispersion stability of the system, and is easy to obtain and low in cost, which is conducive to industrial production.

[0060] In some embodiments of the present application, in the step S1, the pore-eliminating agent is selected from nitrogen-containing compounds and / or polyethers. It is worth mentioning that the use of the above-mentioned pore-eliminating agents in the present application has good pore-eliminating effect and does not produce other side reactions, which is conducive to the adjustment of the porosity of titanium dioxide particles. In some embodiments of the present application, in the step S1, the nitrogen-containing compound is selected from any one or a combination of at least two of trialkyl melamine, cyanuric chloride melamine, and fatty amine.

[0061] In some embodiments of the present application, in the step S1, the polyether is selected from any one or a combination of at least two of oxirane and propylene oxide block copolymer and glycerol propylene oxide copolyether.

[0062] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to the stabilizer is 1:(0.01-1.5).

[0063] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to the stabilizer is 1:(0.15-0.3).

[0064] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to the complexing agent is 1:(0.1-15).

[0065] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to the complexing agent is 1:(0.5-3).

[0066] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to water is 1:(0.01-2).

[0067] In some embodiments of the present application, in the step S1, the weight ratio of the titanium source to water is 1:(0.15-0.5).

[0068] In some embodiments of the present application, in the step S1, the heating temperature is 20-150℃.

[0069] In some embodiments of the present application, in the step S1, the heating temperature is 50-90℃.

[0070] In some embodiments of the present application, the heating time in step S1 is 1-30 hours.

[0071] In some embodiments of the present application, the heating time in step S1 is 6-15 hours.

[0072] In some embodiments of the present application, the weight ratio of the titanium dioxide precursor to the pore-eliminating agent in step S2 is 1:(0.01-0.2).

[0073] In some embodiments of the present application, the weight ratio of the titanium dioxide precursor to the pore-eliminating agent in step S2 is 1:(0.01-0.1).

[0074] In some embodiments of the present application, the titanium dioxide precursor and the pore-eliminating agent in step S2 are subjected to hydrothermal reaction.

[0075] In some embodiments of the present application, the heating temperature in step S2 is 100-250°C.

[0076] In some embodiments of the present application, the heating temperature in step S2 is 180-250°C.

[0077] In some embodiments of the present application, the heating time in step S2 is 1-28 hours.

[0078] In some embodiments of the present application, the heating time in step S2 is 12-24 hours.

[0079] In some embodiments of the present application, an aqueous titanium dioxide dispersion is prepared by the above method; wherein the particle size of the titanium dioxide in the aqueous titanium dioxide dispersion is 1-50 nm, and / or the refractive index of the aqueous titanium dioxide dispersion with a solid content of 35 wt.% is 1.52-1.66.

[0080] In some embodiments of the present application, the aqueous titanium dioxide dispersion as described above is used in the field of optics, for example, the titanium dioxide dispersion is used as an optical coating.

[0081] In some embodiments of the present application, an optical coating contains the above aqueous titanium dioxide dispersion.

[0082] In the present application, the dispersion device can be understood as any device or technical means in the field that can disperse materials in the form of small droplets in the corresponding medium, including but not limited to mechanical stirring, magnetic stirring, ultrasonic, homogenizer, colloid mill, etc.

[0083] The washing and separation in the present application aims to remove impurities, including excess additives, etc., in the obtained primary dispersion of titanium dioxide particles. The separation equipment is a separation equipment known to those skilled in the art, including but not limited to centrifuges, ultrafiltration devices, dialysis devices, etc.

[0084] In some embodiments of the present application, the refractive index of the aqueous titanium dioxide dispersion is measured using a Hyphenated Instruments automatic refractometer A670; the measurement method is in accordance with GB / T 614-2006.

[0085] In some embodiments of the present application, the porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion is measured using a Micromeritics AutoPore 9605, and the measurement method is in accordance with GBT 21650.1-2008.

[0086] The titanium dioxide particles prepared by the method of the present application have an average particle size of 1-50 nanometers and have low porosity. The pores of the titanium dioxide powder particles include intraparticle pores and interparticle pores, both of which have adverse effects on the increase of the refractive index of the titanium dioxide dispersion. The low porosity in the present application is achieved for the following reasons: (1) the titanium oxide synthesis uses an organic titanium source, which is stable in nature, and the generated precursor has high crystallinity and crystallization, which is beneficial to adjusting the porosity of the obtained titanium dioxide particles; (2) the stabilizer added in the synthesis of the precursor is beneficial to controlling the titanium source to always be at a stable dissociation rate, reducing the impurities of titanium dioxide, and is beneficial to reducing the intraparticle and interparticle porosity of the titanium dioxide particles; (3) the complexing agent added in the synthesis of the precursor can improve the solubility of the titanium source, adjust the condensation reaction rate, ensure the uniform dispersibility of the precursor, and is beneficial to reducing the intraparticle and interparticle porosity of the titanium dioxide particles; (4) the pore-eliminating agent added in the synthesis of the primary dispersion has a positive eliminating effect on reducing the intraparticle and interparticle porosity. The porosity can be measured by a method known to those skilled in the art. The porosity of the titanium dioxide particles in the embodiments of the present application ranges from 5.31% to 18.26%, and the refractive index of the aqueous titanium dioxide dispersion with a solid content of 35 wt.% ranges from 1.52 to 1.66.

[0087] It is worth noting that a high porosity will reduce the refractive index, so it is necessary to reduce both porosities as much as possible, but it is not possible to completely eliminate them.

[0088] In the present application, the obtained aqueous titanium dioxide dispersion liquid is dried to obtain titanium dioxide powder particles, and the porosity is measured, so the porosity of the titanium dioxide particles in the specification of the present application refers to the inherent properties of the titanium dioxide powder particles, including the intraparticle pores and the interparticle pores; in addition, the porosity of the titanium dioxide particles has nothing to do with the solid content of the dispersion liquid, because the porosity is measured after the dispersion liquid is dried into powder, and the solid content is only related to the refractive index.

[0089] Example 1

[0090] This example provides the following preparation method to prepare the above-mentioned aqueous titanium dioxide dispersion liquid:

[0091] S1, 249 g of titanium butoxide, 60 g of propylene glycol methyl ether, 18 g of acetic acid are fully mixed and a transparent mixture is obtained, 12 g of deionized water is added, stirred for 10 min to fully mix, heated to 80℃ and kept at this temperature for 6 h to obtain a titanium dioxide precursor, at this time the obtained titanium dioxide precursor is a mixture of un-pored titanium dioxide and un-reacted titanium compound;

[0092] S2, 120 g of the titanium dioxide precursor and 6 g of the ethylene oxide and propylene oxide block copolymer are put into a dispersion device for full mixing, specifically, the reactant system is mechanically stirred in the dispersion device, the stirring speed is 500 rpm, then it is put into a reaction kettle, and then the hydrothermal reaction is carried out in a high-pressure reactor at 250℃ and a pressure of 2.5 MPa for 24 h to obtain a primary dispersion liquid;

[0093] S3, the primary dispersion liquid is subjected to centrifugal treatment to remove the supernatant, the obtained lower layer gel is subjected to washing treatment to remove impurities, and the solid content is adjusted to 35 wt.%, to obtain an aqueous titanium dioxide dispersion liquid.

[0094] Using detection means well known to those skilled in the art, it is measured that the porosity of the titanium dioxide particles in the above-mentioned aqueous titanium dioxide dispersion liquid is 12.72%, and the refractive index of the dispersion liquid is 1.59 when the solid content is 35 wt.%.

[0095] It is worth noting that the specific grade of the ethylene oxide and propylene oxide block copolymer in the above-mentioned step S2 is BASF PE6200.

[0096] Example 2

[0097] The difference between this example and Example 1 is:

[0098] 1. Replace 249 g of titanium butoxide in step S1 with 175 g of titanium isopropoxide;

[0099] 2. The amount of propylene glycol methyl ether in step S1 is increased from 60 g to 490 g;

[0100] 3. The acetic acid in step S1 is replaced by hydrochloric acid;

[0101] 4. The amount of deionized water in step S1 is reduced from 12 g to 6 g;

[0102] 5. The amount of ethylene oxide and propylene oxide block copolymer in step S2 is changed from 6 g to 1.2 g (i.e. the amount of pore-eliminating agent is 1% of the precursor mass);

[0103] 6. The heating temperature in step S2 is reduced to 200 °C and the heating time is shortened to 18 h.

[0104] Using detection means well known to those skilled in the art, it is found that the porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion is 18.26%, and the refractive index of the dispersion is 1.52 at a solid content of 35 wt.%.

[0105] Example 3

[0106] The difference between this example and Example 1 is that:

[0107] 1. The 249 g of titanium butoxide in step S1 is replaced by 182 g of titanium acetylacetonate;

[0108] 2. The 60 g of propylene glycol methyl ether in step S1 is replaced by 364 g of ethylene glycol ethyl ether;

[0109] 3. The acetic acid in step S1 is replaced by triethanolamine;

[0110] 4. The amount of deionized water in step S1 is increased from 12 g to 55 g;

[0111] 5. The amount of ethylene oxide and propylene oxide block copolymer in step S2 is changed from 6 g to 24 g (i.e. the amount of pore-eliminating agent is 20% of the precursor mass);

[0112] 6. The heating temperature in step S2 is reduced to 100 °C and the heating time is shortened to 12 h.

[0113] Using detection means well known to those skilled in the art, it is found that the porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion is 5.31%, and the refractive index of the dispersion is 1.66 at a solid content of 35 wt.%.

[0114] Example 4

[0115] The difference between this example and Example 1 is that:

[0116] 1. Replace 18 g acetic acid in Step S1 with 36 g acetylacetone;

[0117] 2. Replace propylene glycol methyl ether in Step S1 with benzyl alcohol;

[0118] 3. Increase the amount of deionized water in Step S1 from 12 g to 38 g;

[0119] 4. Replace 6 g of the ethylene oxide and propylene oxide block copolymer in Step S2 with 6 g of glycerol propylene oxide copolyether (i.e., the amount of pore-eliminating agent is 5% of the mass of the precursor);

[0120] 5. Reduce the heating temperature in Step S2 to 180°C and shorten the heating time to 1 h.

[0121] Using detection means well known to those skilled in the art, it was found that the porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion was 15.08%, and the refractive index of the dispersion was 1.56 at a solid content of 35 wt.%.

[0122] Example 5

[0123] The difference between this example and Example 1 is that:

[0124] 1. Replace 249 g titanium butoxide in Step S1 with 175 g titanium isopropoxide;

[0125] 2. Increase 18 g acetic acid in Step S1 to 52 g;

[0126] 3. Replace 60 g propylene glycol methyl ether in Step S1 with 175 g dipropylene glycol methyl ether;

[0127] 4. Increase the amount of deionized water in Step S1 from 12 g to 17.5 g;

[0128] 5. Replace 6 g of the ethylene oxide and propylene oxide block copolymer in Step S2 with 18 g of cyanuric chloride melamine (i.e., the amount of pore-eliminating agent is 15% of the mass of the precursor);

[0129] 6. Reduce the heating temperature in Step S2 to 200°C and shorten the heating time to 18 h.

[0130] Using detection means well known to those skilled in the art, it was found that the porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion was 8.47%, and the refractive index of the dispersion was 1.63 at a solid content of 35 wt.%.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 1 is that: in the step S1, the amount of acetic acid added is 0, i.e., no stabilizer is added at all.

[0133] The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion described above was measured to be 33.18%, and the refractive index of the dispersion was measured to be 1.36 at a solid content of 35 wt.% using detection means well known to those skilled in the art.

[0134] Comparative Example 2

[0135] This comparative example differs from Example 2 in that the amount of propylene glycol methyl ether added in the step S1 was 0, i.e. no complexing agent was added at all.

[0136] The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion described above was measured to be 27.35%, and the refractive index of the dispersion was measured to be 1.44 at a solid content of 35 wt.% using detection means well known to those skilled in the art.

[0137] Comparative Example 3

[0138] This comparative example differs from Example 3 in that the amount of titanium acetylacetonate and benzyl alcohol added in the step S2 was 0, i.e. no pore-destroying agent was added at all.

[0139] The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion described above was measured to be 39.67%, and the refractive index of the dispersion was measured to be 1.31 at a solid content of 35 wt.% using detection means well known to those skilled in the art.

[0140] Comparative Example 4

[0141] This comparative example differs from Example 4 in that the amount of acetylacetone, acetic acid and glycerol propylene oxide copolyether added in the step S2 was 0, i.e. no complexing agent, stabilizer and pore-destroying agent was added at all.

[0142] The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion described above was measured to be 58.64%, and the dispersion of the titanium dioxide particles in the aqueous titanium dioxide dispersion prepared in this comparative example was poor.

[0143] Comparative Example 5

[0144] This comparative example differs from Example 1 in that the heating temperature in the step S2 was 50°C.

[0145] The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion described above was measured to be 22.16%, and the refractive index of the dispersion was measured to be 1.48 at a solid content of 35 wt.% using detection means well known to those skilled in the art.

[0146] Comparative Example 6

[0147] The difference between the comparative example and Example 1 is that the heating temperature of step S2 is 300°C.

[0148] The porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion is 29.53%, and the refractive index of the dispersion is 1.41 at a solid content of 35 wt.% by using detection means well known to those skilled in the art.

[0149] Comparative Example 7

[0150] The difference between the comparative example and Example 1 is that the heating time of step S2 is 40 h.

[0151] The porosity of the titanium dioxide particles in the above aqueous titanium dioxide dispersion is 27.92%, and the refractive index of the dispersion is 1.44 at a solid content of 35 wt.% by using detection means well known to those skilled in the art.

[0152] The above description is merely a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, and all of them should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. In addition, the principles and implementation manners of the present application are described by using specific examples in the specification, and the above examples are only used to help understand the method and core idea of the present application, and the content of the specification should not be understood as a limitation of the present application.

Claims

1. An aqueous titanium dioxide dispersion, characterized in that, The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion is 5-20%; and, the refractive index of the aqueous titanium dioxide dispersion with a solid content of 35 wt.% is 1.5-1.7; The preparation method of the aqueous titanium dioxide dispersion comprises the following steps: S1, mixing a titanium source, a coordination agent and a stabilizer, then mixing the obtained mixture with water and heating to obtain a titanium dioxide precursor; S2, mixing the titanium dioxide precursor and a pore-eliminating agent and heating to obtain a primary dispersion; S3, centrifuging the primary dispersion to remove supernatant, washing the obtained lower layer gel after centrifugation, and adjusting the solid content to obtain the aqueous titanium dioxide dispersion; The titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, and titanium acetylacetonate; The pore-eliminating agent is selected from a nitrogen-containing compound and / or a polyether; In the step S1, the heating temperature is 20-150℃, and the heating time is 1-30h; In the step S2, the titanium dioxide precursor and the pore-eliminating agent undergo a hydrothermal reaction, the heating temperature is 100-250℃, and the heating time is 1-28h.

2. The aqueous titanium dioxide dispersion according to claim 1, characterized in that, The porosity of the titanium dioxide particles in the aqueous titanium dioxide dispersion is 5.31-18.26%; and, the refractive index of the aqueous titanium dioxide dispersion with a solid content of 35 wt.% is 1.52-1.

66.

3. The aqueous titanium dioxide dispersion of claim 1, wherein The titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, and titanium acetylacetonate.

4. The aqueous titanium dioxide dispersion of claim 1, wherein The coordination agent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, butanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, and benzyl alcohol.

5. The aqueous titanium dioxide dispersion of claim 1, wherein The stabilizer is selected from any one or a combination of at least two of acetic acid, hydrochloric acid, acetylacetone, and triethanolamine.

6. The aqueous titanium dioxide dispersion of claim 1, wherein The nitrogen-containing compound is selected from any one or a combination of at least two of trialkyl melamine, cyanuric chloride melamine, and fatty amine; and / or, the polyether is selected from any one or a combination of at least two of an ethylene oxide and propylene oxide block copolymer, glycerol propylene oxide copolyether, and the like.

7. A method for producing the aqueous titanium dioxide dispersion according to any one of claims 1 to 6, characterized by, The preparation method comprises the following steps: S1, mixing a titanium source, a coordination agent and a stabilizer, then mixing the obtained mixture with water and heating to obtain a titanium dioxide precursor; S2, mixing the titanium dioxide precursor and a pore-eliminating agent and heating to obtain a primary dispersion; S3, centrifuging the primary dispersion to remove supernatant, washing the obtained lower layer gel after centrifugation, and adjusting the solid content to obtain the aqueous titanium dioxide dispersion.

8. The production method according to claim 7, characterized by, The titanium source is selected from any one or a combination of at least two of titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide, and titanium acetylacetonate.

9. The preparation method according to claim 7, characterized in that, The coordination agent is selected from any one or a combination of at least two of methanol, ethanol, isopropanol, butanol, propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, and benzyl alcohol.

10. The preparation method according to claim 7, characterized in that, The stabilizer is selected from any one or a combination of at least two of acetic acid, hydrochloric acid, acetylacetone, triethanolamine.

11. The preparation method according to claim 7, characterized in that, The nitrogen-containing compound is selected from any one or a combination of at least two of trialkyl melamine, cyanuric chloride melamine, fatty amine; And / or, the polyether is selected from any one or a combination of at least two of oxirane and propylene oxide block copolymer, glycerol propylene oxide copolyether, 12. The method of claim 7, wherein, In the step S1, the weight ratio of the titanium source and the stabilizer is 1:(0.01-1.5); And / or, in the step S1, the weight ratio of the titanium source and the complexing agent is 1:(0.1-15).

13. The preparation method according to claim 7, characterized in that, In the step S1, the weight ratio of the titanium source and the stabilizer is 1:(0.15-0.3); And / or, in the step S1, the weight ratio of the titanium source and the complexing agent is 1:(0.5-3).

14. The method of claim 7, wherein, In the step S1, the weight ratio of the titanium source and water is 1:(0.01-2).

15. The method of claim 7, wherein the method further comprises, In the step S1, the weight ratio of the titanium source and water is 1:(0.15-0.5).

16. The method of claim 7, wherein, In the step S1, the heating temperature is 20-150℃; And / or, in the step S1, the heating time is 1-30h.

17. The method of claim 7, wherein the method further comprises, In the step S1, the heating temperature is 50-90℃; And / or, in the step S1, the heating time is 6-15h.

18. The method of claim 7, wherein, In the step S2, the weight ratio of the titanium dioxide precursor and the pore-eliminating agent is 1:(0.01-0.2).

19. The method of claim 7, wherein, In the step S2, the weight ratio of the titanium dioxide precursor and the pore-eliminating agent is 1:(0.01-0.1).

20. The method of claim 7, wherein, In the step S2, the titanium dioxide precursor and the pore-eliminating agent undergo hydrothermal reaction, and the heating temperature is 100-250℃; And / or, in the step S2, the heating time is 1-28h.

21. The method of claim 7, wherein, In the step S2, the titanium dioxide precursor and the pore-eliminating agent undergo hydrothermal reaction, and the heating temperature is 180-250℃; And / or, in the step S2, the heating time is 12-24h.

22. Use of an aqueous titanium dioxide dispersion according to any one of claims 1 to 6 in the field of optics, characterized in that, The aqueous titanium dioxide dispersion is used as an optical coating.

23. An optical coating, characterized by, The optical coating contains the aqueous titanium dioxide dispersion as claimed in any one of claims 1-6.

Images