Surface-modified transition metal oxide nanoparticles, methods for producing the same, and curable compositions and articles containing the same.

Abstract

A method for producing surface-functionalized transition metal oxide nanoparticles includes providing a sol containing transition metal oxide nanoparticles dispersed in an aqueous liquid medium having a pH of 3.5 or less, combining the sol with an extractant composition containing at least one carboxylic acid and at least one organic amine, and a water-immiscible organic solvent, separating at least a portion of the organic phase from the aqueous phase, and then at least partially removing the water-immiscible organic solvent. The carboxylic acid has 6 to 30 atoms. The organic amine is a compound having the formula R 2 R 3 NH (in the formula, R 2 is a hydrocarbyl group having 6 to 30 carbon atoms, and R 3 is H, or an alkyl group having 1 to 4 carbon atoms. The at least one organic amine is present in an amount sufficient to raise the pH to at least 5, thereby forming separate, separable aqueous and organic phases. Surface-modified nanoparticle compositions, curable compositions, and articles comprising the same are also disclosed.

Description

[Background technology]

[0001] Metal oxide nanoparticles, particularly titania or zirconia nanoparticles, are used to increase the refractive index (RI) of coatings and composites. Typically, the nanoparticles are synthesized in water and stabilized with an inorganic acid or base. For example, acidic nanoparticle sols may contain nitric acid, hydrochloric acid, or acetic acid. Basic sols may contain ammonium hydroxide or tetramethylammonium hydroxide. For use in coatings, metal oxide nanoparticles must typically be surface-modified to improve their compatibility with desired resins such as acrylates or polymers.

[0002] U.S. Patent No. 8,829,079 (Shultz et al.) discloses a method for preparing carboxylic acid-acid stabilized zirconia nanoparticle sols. A carboxylic acid and a water-miscible solvent are added to surface-modify the particles. Then, water and excess carboxylic acid (e.g., formic acid, acetic acid) are removed. The surface-modified nanoparticles can be combined with an acrylic monomer to obtain a 100% solid nanocomposite precursor.

[0003] For some applications, it is desirable to use nanoparticles with a higher refractive index (RI) than zirconia. For example, anatase titania has an RI of 2.49 (η). D ) has, which is zirconia (RI=2.13, η D This enables composites with a higher refractive index than ).

[0004] Commercially available titania nanoparticles are often stabilized with strong acids. For example, nitric acid-stabilized titania nanoparticles are available from Nyacol Nanotechnologies (Ashland, Massachusetts), and hydrochloric acid-stabilized titania nanoparticles are available from Showa Denko (Tokyo, Japan). [Overview of the Initiative]

[0005] The surface functionalization method described above, used for carboxylic acid-stabilized zirconia particles, does not work for the titania particles described above because the weakly acidic carboxylic acid cannot replace the strong mineral acid on the particle surface. A new surface functionalization method is needed for titania nanoparticles stabilized with strong acids.

[0006] This disclosure solves this problem by using surface functionalization by extraction. Acid-stabilized aqueous nanoparticles are treated with an organic solvent (immiscible with water), a carboxylic acid, and an excess of alkylamine. The alkylamine neutralizes the strong mineral acid and deprotonates the alkane carboxylic acid. The resulting alkane carboxylate then binds to the surface of the nanoparticles, which makes the particles hydrophobic and leads to their migration into the organic phase so that the nanoparticles can be easily isolated. Salt byproducts remain in the aqueous phase and are easily removed. The solvent-dispersed particles have improved compatibility with monomers or polymers and can therefore be used to produce high refractive index coatings and composites.

[0007] Therefore, in one aspect, the present disclosure relates to a method for producing surface-functionalized nanoparticles, To provide a sol containing transition metal oxide nanoparticles dispersed in an aqueous liquid medium having a pH of 3.5 or less and stabilized with at least one mineral acid, The sol is combined with an extractant composition comprising at least one carboxylic acid and at least one organic amine, as well as a water-immiscible organic solvent. Each of at least one carboxylic acid independently possesses the formula R 1 -CO2H (in the formula, R 1 It is represented by a hydrocarbyl group having 6 to 30 carbon atoms. Each of at least one organic amine is in formula R 2 R 3 NH (in the formula, R 2 R is a hydrocarbyl group having 6 to 30 carbon atoms. 3is represented by H or an alkyl group having 1 to 4 carbon atoms), and at least one organic amine is present in an amount sufficient to neutralize at least the acid present in the sol, thereby forming a separate, separable aqueous phase and an organic phase, and separating at least a portion of the organic phase from the aqueous phase and then at least partially removing the water-immiscible organic solvent to obtain at least a portion of the surface-functionalized transition metal oxide nanoparticles A method comprising

[0008] In another aspect, the present disclosure is a surface-modified nanoparticle composition comprising surface-functionalized transition metal oxide nanoparticles, each of the surface-functionalized transition metal oxide nanoparticles comprising a respective transition metal oxide core having a surface layer thereon, the surface layer having the formula R 1 -CO2 - (wherein R 1 is a hydrocarbyl group having 6 to 30 carbon atoms) and a bound organic carboxylate represented by the formula R 2 R 3 NH2 + (wherein R 2 represents a hydrocarbyl group having 6 to 30 carbon atoms and R 3 represents H or an alkyl group having 1 to 4 carbon atoms), and provides a surface-modified nanoparticle composition comprising at least one organic ammonium cation.

[0009] In yet another aspect, the present disclosure provides a curable composition comprising a surface-modified nanoparticle composition according to the present disclosure, at least one curable monomer, and a curing agent. The curable composition can be used to produce a nanocomposite layer on a substrate.

[0010] Thus, in yet another aspect, the present disclosure provides an article comprising a substrate, the substrate having a layer of a curable composition according to the present disclosure disposed thereon that is at least partially cured.

[0011] As used herein, The term "aqueous" means containing at least 20 weight percent water, and in some cases, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, or even at least 99 weight percent water.

[0012] The term "hydrocarbyl" refers to a monovalent organic group consisting of carbon and hydrogen.

[0013] The term "immiscibility" means that they cannot be mixed to form a homogeneous mixture.

[0014] The term "mineral acid" refers to an inorganic acid.

[0015] The term "nanoparticle" refers to a particle having a volume average diameter of 100 nanometers or less.

[0016] The term "sol" refers to a stable colloidal dispersion.

[0017] The term "strong acid" refers to an acid that completely dissociates in water at a pressure of 25 °C and 1 atmosphere (101 kPa). Examples of inorganic strong acids include hydroiodic acid, hydrobromic acid, hydrochloric acid, perchloric acid, chloric acid, sulfuric acid (I), and nitric acid.

[0018] The term "transition metal" refers to metals in Groups 3 - 12 of the IUPAC periodic table of the elements, including lanthanides and actinides.

[0019] The features and advantages of the present disclosure will be further understood by considering the detailed description and the appended claims.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic side view of an exemplary article 100 according to the present disclosure.

[0021] Those skilled in the art can devise many other modifications and embodiments, which should be understood to be within the scope and spirit of the principles of this disclosure. Figures may not be drawn to scale. [Modes for carrying out the invention]

[0022] The methods according to this disclosure are suitable for practices using any transition metal oxide sol having a pH of 3.5 or less, preferably stabilized with a strong acid (e.g., nitric acid, sulfuric acid, or hydrochloric acid). Preferred transition metal oxides are those of Group 3 and 4 of the periodic table (IUPAC) and lanthanides (e.g., Y, Ti, Zr, Ce). Of these, zirconia sol and titania sol are most preferred.

[0023] Examples of commercially available acidic transition metal oxide sols with a pH of ≤3.5 include sols from Nyacol Nanotechnologies (Ashland, Massachusetts), such as ceria sol (NYACOL CEO2(NO3) (pH=1.5, average particle size=10~20nm, nitrate stabilized)), zirconia sol (NYACOL ZR 10 / 15 (average particle size=5~15nm, pH=2.0~3.0, nitrate stabilized) (NYACOL ZR 100 / 20 (100nm, pH3.0, nitrate stabilized)), titania sol (e.g., NYACOL TISOL A (average particle size 10~25nm, nitric acid stabilized, pH1.3~1.8)), and sols from Sakai Chemical Industry (Osaka, Japan) (e.g., CSB Anatase 100% (aqueous sol (nitric acidity pH<1), particle size 7nm by XRD)).

[0024] Transition metal oxide nanoparticles may have a volume-average diameter of ≤100 nanometers (nm), ≤75 nm, ≤50 nm, ≤40 nm, ≤30 nm, ≤25 nm, or even ≤20 nm. The volume-average nanoparticle diameter can be determined using known techniques, such as ASTM E2490-09 (2015) "Standard Guide for Measurement of Particle Size Distribution of Nanomaterials in Suspension by Photon Correlation Spectroscopy (PCS)".

[0025] Useful carboxylic acids are those of formula R 1 -CO2H (in the formula, R 1 The carboxylic acid has a hydrocarbyl group having 6 to 30 carbon atoms, more preferably 8 to 18 carbon atoms, more preferably 9 to 16 carbon atoms, and more preferably 10 to 12 carbon atoms. The carboxylic acid may be linear, branched or cyclic, aromatic or aliphatic, and saturated or unsaturated. Specific examples include octanoic acid, nonanoic acid, decanoic acid, 2-ethylhexanoic acid, undecanoic acid, lauric acid, hexadecanoic acid, citronellic acid, stearic acid, tetracosanoic acid, and n-triacontanoic acid.

[0026] Useful organic amines are given by formula R 2 R 3 NH (in the formula, R 2 (This represents a hydrocarbyl group having 1 to 30 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 10 carbon atoms). 2 Examples include methyl, ethyl, propyl, butyl, n-hexyl, cyclohexyl, phenyl, benzyl, phenethyl, n-octyl, 2-ethylhexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, n-tetracosyl, and n-triacontyl. 3 R represents H, or an alkyl group having 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, butyl). In some embodiments, the organic amine is represented by formula R4 CH2NH2 (wherein, R 4 It is represented by (where represents a hydrocarbyl group having 1 to 29 carbon atoms). Aromatic amines have a relatively higher refractive index than aliphatic amines, which can be particularly desirable in some cases.

[0027] The organic amine is added in an amount sufficient to raise the pH to at least 5, thereby forming a separate, separable (e.g., not a stable emulsion) aqueous phase and organic phase.

[0028] The use of organic amines is important for this method. Many bases, especially inorganic bases, interact with carboxylic acids to produce surfactants that can stabilize emulsions between the organic and aqueous phases. However, organic amines interact with carboxylic acids to produce hydrophobic salt pairs that are not efficient emulsifiers.

[0029] Examples of solvents include: hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, toluene, xylene, mineral spirits, and combinations thereof; chlorocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, and combinations thereof; esters such as ethyl acetate, propyl acetate, butyl acetate, and combinations thereof; ketones such as methyl isobutyl ketone, and combinations thereof; ethers such as methyl t-butyl ether, diethyl ether, and combinations thereof; and combinations thereof.

[0030] In practice of the method according to this disclosure, a simple mixing procedure is effective for combining the transition metal oxide sol, carboxylic acid, and organic amine. In some cases, high shear mixing conditions are preferred. After mixing, the mixture is allowed to stand while the aqueous and organic phases separate. The organic phase can then be easily separated from the aqueous phase using conventional liquid extraction techniques, and the organic solvent can be removed by heating and / or vacuum evaporation.

[0031] Generally, the above process yields transition metal oxide nanoparticles with residual amounts of associated protonated forms of organic amines. Typically, these organic ammonium cations are not harmful in the end use and can remain combined with the transition metal oxide nanoparticles, allowing them to be used without further purification; however, in some cases, further purification may be desirable. Purification methods include, for example, centrifugation and tangential flow filtration.

[0032] Transition metal oxide nanoparticles may be included in a curable composition comprising at least one curable monomer, an optional curing agent, and an optional solvent. Exemplary monomers include epoxides, (meth)acrylic monomers and oligomers, self-crosslinked latexes, cyanates, and urethanes (both one-part and two-part). Of these, (meth)acrylic monomers and oligomers are particularly useful. As used herein, the term "(meth)acrylic" refers to acrylic and / or methacrylic. The selection of catalysts and / or initiators is within the capabilities of those skilled in the art.

[0033] Exemplary (meth)acrylic monomers and oligomers comprise at least one monomer containing at least one (meth)acrylic group. In many preferred embodiments, the at least one monomer comprises at least two or at least three monomers containing at least one (meth)acrylic group. In some embodiments, the at least one monomer comprises aliphatic, alicyclic, and / or aromatic (meth)acrylates of difunctional, trifunctional, tetrafunctional, and / or pentafunctional monomers or oligomers.

[0034] (meth)acrylic group-containing monomers are widely available from, for example, Sartomer Co. (Exton, Pennsylvania) and other distributors. Suitable monomers include mono-, di-, or poly-(meth)acrylates, such as (meth)acrylic acid, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxylethyl (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, bis[1-(2-acrylooxy)]-p-ethoxyphenyldimethylmethane, bis[1-(3-acrylooxy-2-hydroxy)]-p-prop Xy-phenyl-dimethylmethane, bis(trimethylolpropane)tetraacrylate, chlorinated polyester (meth)acrylate, diethylene glycol di(meth)acrylate, bisphenol A diglycidyl (meth)acrylate, dodecyl (meth)acrylate, epoxy (meth)acrylate oligomer, ethoxylated or propoxylated glycerol tri(meth)acrylate, ethyl (meth)acrylate, ethylene glycol di(meth)acrylate, glycerol di(meth)acrylate Glycerol tri(meth)acrylate, hexanediol di(meth)acrylate, hexyl(meth)acrylate, hydroxybutyl(meth)acrylate, hydroxyfunctional caprolactone ester(meth)acrylate, hydroxyisopropyl(meth)acrylate, hydroxymethyl(meth)acrylate, hydroxypropyl(meth)acrylate, isobornyl(meth)acrylate, isobutyl(meth)acrylate, isodecyl(meth)acrylate, isononyl(meth)acrylate Isooctyl (meth)acrylate, isopropyl (meth)acrylate, lauryl (meth)acrylate, methyl (meth)acrylate, n-butyl (meth)acrylate, neopentyl glycol di(meth)acrylate, n-hexyl (meth)acrylate, nonylphenol ethoxylate (meth)acrylate, octyl (meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol triacrylate, poly(ethylene glycol) di(meth)acrylate,Polybutadiene (meth)acrylate, polyester (meth)acrylate oligomer, polyurethane (meth)acrylate, silicone (meth)acrylate oligomer, sorbitol hexaacrylate, stearyl (meth)acrylate, tetraethylene glycol di(meth)acrylate, tetrahydrafurfuryl (meth)acrylate, triethylene glycol di(meth)acrylate, tris(hydroxyethyl) isocyanurate tri(meth)acrylate, β-carboxyethyl (meth)acrylate Examples include 1,1,1-trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, hexane-2,4,6-triol tri(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-cyclohexanediol diacrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and combinations thereof.

[0035] (Meth)acrylic monomers may be present in the composition in an amount of at least 20, at least 30, at least 50, at least 70, at least 80, at least 90, at least 95, or even at least 98 percent by weight, based on the total weight of the composition, but this is not a requirement.

[0036] Examples of free radical initiators include, but are not required, peroxides (e.g., benzoyl peroxide) and azo compounds (e.g., azobisisobutyronitrile) and thermal initiators such as photoinitiators (e.g., type I and / or type II photoinitiators), typically in amounts of less than about 10 weight percent, and more typically less than 5 weight percent.

[0037] Exemplary photoinitiators include α-cleavage photoinitiators, such as benzoin and its derivatives, e.g., α-methylbenzoin; α-phenylbenzoin; α-allylbenzoin; α-benzylbenzoin; benzoin ethers, e.g., benzyldimethylketal (available from Ciba Specialty Chemicals (Tarrytown, New York) as IRGACURE 651), benzoin methyl ether, benzoin ethyl ether, benzoin n-butyl ether; acetophenone and its derivatives, e.g., 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxycyclohexylphenyl ketone. One useful photoinitiator, a bifunctional α-hydroxyketone, is available from IGM Resins (Waalwijk, The Netherlands) as ESACURE ONE. Other exemplary photoinitiators include anthraquinones (e.g., anthraquinone, 2-ethylanthraquinone, 1-chloroanthraquinone, 1,4-dimethylanthraquinone, 1-methoxyanthraquinone) and benzophenones and their derivatives (e.g., phenoxybenzophenone, phenylbenzophenone).

[0038] Curing can be achieved / accelerated, for example, by heating (e.g., in an oven or by exposure to infrared radiation) and / or by exposure to chemical radiation (e.g., ultraviolet radiation and / or electromagnetic visible light). The selection of chemical sources (e.g., xenon flash lamps, medium-pressure mercury arc lamps) and exposure conditions is within the capabilities of those skilled in the art.

[0039] Referring to Figure 1, the exemplary article 100 comprises a substrate 110. Layer 120 is disposed on the substrate 110. Layer 120 comprises at least a partially cured curable composition according to the present disclosure. Examples of exemplary substrates include optical films (e.g., privacy films, brightness-enhancing films, mirror films, light-extracting films) and display elements (OLED displays).

[0040] Articles can be prepared by coating a substrate with the curable composition according to the present disclosure (for example, by roll coating, knife coating, spraying, or dipping coating) and curing it (for example, by heat and / or chemical rays).

[0041] The purposes and merits of this disclosure are further illustrated by the following non-limiting embodiments, but the specific materials and their quantities, as well as other conditions and details, referenced in these embodiments should not be construed as unduly limiting this disclosure. [Examples]

[0042] Unless otherwise stated, all parts, percentages, ratios, etc., in the examples and other parts of this specification are by weight. The materials used in the examples are reported in Table 1 below.

[0043] [Table 1]

[0044] Other solvents and chemicals were obtained from Alfa Aesar (Tewksbury, Massachusetts) and used as received.

[0045] Test Method 1: Measurement of transmittance and haze of coated film Total transmittance and haze measurements were performed using an integrating sphere instrument with a BYK Haze-Gard Plus, Model No. 4725 (BYK-Gardner USA (Columbia, Maryland)), 0° / diffuse geometry, and CIE standard light source C. For transmittance and haze measurements, the sample was placed directly into the haze port. The reported values ​​are the average of three measurements.

[0046] Test Method 2: Measurement of the refractive index of the film coating The refractive index of the coated film at three wavelengths was measured using a Metricon Prism Coupler (Metricon Corp. (Pennington, NJ)).

[0047] Example 1: Extraction of NTB-01 TiO2 nanoparticles with toluene 4.0 g of NTB-01 nanoparticle sol, 2.0 g of water, 5.0 g of toluene, 900 mg of citronellic acid solution, and 1.35 g of benzylamine solution were placed in a vial. The vial was capped and mixed with a vortex mixer. The layers were separated, and the lower clear aqueous layer was removed with a pipette. BYK9010 (20 mg) was added, and the mixture was allowed to stand for 20 minutes. Anhydrous sodium sulfate (0.5 g) was added, and the mixture was mixed again with a vortex mixer. The mixture was filtered through a 1 micron glass fiber syringe tip filter. A white dispersion (6.86 g) was obtained. A small aliquot of this dispersion was evaporated to dryness, and the solids content percentage was estimated to be 8.79 wt% by the change in mass, which means a yield of 603 mg of particles.

[0048] Example 2: Extraction of TISOL-A with toluene 150.0 g of TISOL-A nanoparticle sol, 150 g of water, 250 g of toluene, 4.75 g of citronellic acid, and 10.7 g of benzylamine were added to a separatory funnel. The mixture was rapidly stirred with an overhead stirrer for 5 minutes, forming a white emulsion. After standing for 30 minutes, the emulsion separated into two distinct layers. The aqueous layer was discarded, and the organic layer was treated with 5.0 g of anhydrous sodium sulfate and then filtered through a 1 micron glass fiber syringe tip filter. A turbid, milky dispersion (232 g) was obtained. A small aliquot of this dispersion was evaporated to dryness, and the solids content percentage was estimated to be 12.6 wt% by the change in mass, which corresponds to a yield of 29.1 g of particles.

[0049] Example 3: Extraction of TISOL-A with heptane 2.0 g of TISOL A nanoparticle sol, 3.0 g of water, 5.0 g of heptane, 550 mg of lauric acid solution, and 120 mg of benzylamine were placed in a vial. The vial was capped and mixed with a vortex mixer. The layers were separated, and the clear aqueous layer at the bottom was removed with a pipette. BYK9010 (10 mg) was added, and the mixture was allowed to stand for 20 minutes. Anhydrous sodium sulfate (0.5 g) was added, and the mixture was mixed again with a vortex mixer. The mixture was filtered through a 1 micron glass fiber syringe tip filter. A turbid, milky dispersion (5.6 g) was obtained. A small aliquot of this dispersion was evaporated to dryness, and the solids content percentage was estimated to be 7.10 wt% by the change in mass, which means a yield of 400 mg of particles.

[0050] Example 4: Extraction of ZR100 / 20 with toluene 4.0 g of ZR100 / 20 nanoparticle sol, 4.0 g of water, 8.0 g of toluene, 700 mg of citronellic acid solution, and 320 mg of benzylamine were placed in a vial. The vial was capped and mixed with a vortex mixer. The layers were separated, and the lower clear aqueous layer was removed with a pipette. Anhydrous sodium sulfate (0.5 g) was added and mixed with a vortex mixer. The mixture was filtered through a 1 micron glass fiber syringe tip filter. A white dispersion (8.26 g) was obtained. A small aliquot of this dispersion was evaporated to dryness, and the solids content percentage was estimated to be 6.17 wt% by the change in mass, which means a yield of 510 mg of particles.

[0051] Example 5: Coating using TiO2 particles dispersed in toluene 3.0 g of the nanoparticle dispersion from Example 1 was placed in a vial, and 465 mg of a 10 wt% acrylate solution dissolved in toluene was added. The acrylate portion of this solution consisted of a 9:1 mixture of M1192:TCDDMDA. A 10 wt% TPO solution (71 mg) in toluene was added. This solution was coated onto a 2 mil (0.05 mm) thick polyethylene terephthalate (PET) film using a #12 wound rod obtained from BYK. After the solvent evaporated, the coating was cured with a high-intensity ultraviolet lamp using a benchtop conveyor system obtained from Heraeus (Hanau, Germany). The system was purged with nitrogen gas, and the coating was cured using a D valve at 100% power while the conveyor belt was running at 30 feet / min. The coating was passed through the system three times.

[0052] Example 6: Coating using TiO2 particles dispersed in toluene A vial was filled with 3.02 g of the nanoparticle dispersion from Example 2, 76 mg of a 10 wt% BYK9010 solution in toluene, and 683 mg of a 10 wt% acrylate solution dissolved in toluene. The acrylate portion of this solution consisted of a mixture of M1192:TCDDMDA in a mass ratio of 9:1. A 10 wt% TPO solution (91 mg) in toluene was added. This solution was coated onto a 2 mil (0.05 mm) thick polyethylene terephthalate (PET) film using a #12 winding rod obtained from BYK. After the solvent was evaporated, the coating was cured with a high-intensity UV lamp using the method described in Example 5.

[0053] Example 7: Coating using TiO2 particles dispersed in heptane A vial was filled with 3.0 g of the nanoparticle dispersion from Example 3 and 408 mg of a 10 wt% acrylate solution dissolved in heptane. The acrylate portion of this solution consisted of a mixture of IBA:HDDA in a mass ratio of 9:1. A 10 wt% TPO solution in toluene (69 mg) was added. This solution was coated onto a 2 mil (0.05 mm) thick polyethylene terephthalate (PET) film using a #12 winding rod obtained from BYK. After the solvent evaporated, the coating was cured with a high-intensity UV lamp using the method described in Example 5.

[0054] Example 8: Coating using ZrO2 particles dispersed in toluene A vial was filled with 2.0 g of the nanoparticle dispersion from Example 4, 25 mg of a 10 wt% BYK9010 solution in toluene, and 222 mg of a 10 wt% acrylate solution dissolved in toluene. The acrylate portion of this solution consisted of a mixture of M1192:TCDDMDA in a mass ratio of 9:1. A 10 wt% TPO solution (30 mg) in toluene was added. This solution was coated onto a 2 mil (0.05 mm) thick polyethylene terephthalate (PET) film using a #12 winding rod obtained from BYK. After the solvent evaporated, the coating was cured with a high-intensity UV lamp using the method described in Example 5.

[0055] Comparative Example 1: UV-curing coating without nanoparticles 2.0 g of a 10% acrylate solution in toluene was placed in a vial. The acrylate portion of this solution consisted of a mixture of M1192:TCDDMDA in a mass ratio of 9:1. A 10% by weight solution of TPO in toluene (40 mg) was added. Using a #12 wound rod obtained from BYK, the solution was coated onto a 2 mil (0.05 mm) thick polyethylene terephthalate (PET) film. After evaporating the solvent, the coating was cured with a high-intensity UV lamp using the method described in Example 5.

[0056] Table 2 below reports the optical properties of the coatings produced in Examples 5-8 and Comparative Example 1.

[0057] [Table 2]

[0058] Table 3 below reports the radioisotopes (RI) of the coatings produced in Examples 5-8 and Comparative Examples 1 and 2.

[0059] [Table 3]

[0060] The foregoing statements are intended to enable those skilled in the art to practice the disclosures set forth in the claims and should not be construed as limiting the scope of the disclosure, which is defined by the claims and all their equivalents. The present invention encompasses the following aspects. (1) A method for producing surface-functionalized transition metal oxide nanoparticles, To provide a sol containing transition metal oxide nanoparticles dispersed in an aqueous liquid medium having a pH of 3.5 or less and stabilized with at least one mineral acid, The sol is combined with an extractant composition comprising at least one carboxylic acid and at least one organic amine, and a water-immiscible organic solvent. Each of the at least one carboxylic acid is independently of formula R 1 -CO 2 H (wherein, R 1 It is represented by a hydrocarbyl group having 6 to 30 carbon atoms. Each of the at least one organic amines is a member of formula R 2 R 3 NH (in the formula, R 2 R is a hydrocarbyl group having 6 to 30 carbon atoms. 3 (where is represented by H, or an alkyl group having 1 to 4 carbon atoms), and the at least one organic amine is present in an amount sufficient to neutralize the acid present in the sol, thereby forming a separate separable aqueous phase and organic phase. To separate at least a portion of the organic phase from the aqueous phase, and then to at least partially remove the water-immiscible organic solvent from the separated organic phase, to obtain at least a portion of the surface-functionalized transition metal oxide nanoparticles, Methods that include... (2) The method according to item 1, wherein the transition metal oxide nanoparticles include at least one of titanium oxide, zirconium oxide, or cerium oxide. (3) The method according to item 1, wherein the transition metal oxide nanoparticles include titanium oxide. (4)R 1 The method according to any one of items 1 to 3, wherein represents a hydrocarbyl group having 8 to 18 carbon atoms. (5)R 1 The method according to any one of items 1 to 3, wherein represents a hydrocarbyl group having 10 to 12 carbon atoms. (6)R 2 The method according to any one of items 1 to 5, wherein represents a hydrocarbyl group having 6 to 18 carbon atoms. (7)R 2 The method according to any of items 1 to 5, wherein represents a hydrocarbyl group having 7 to 10 carbon atoms. (8)R 3 The method described in any of items 1 to 7, wherein H is present. (9) The method according to any one of items 1 to 5, wherein the at least one organic amine comprises at least one of benzylamine, n-octylamine, or 2-ethylhexylamine. (10) The method according to any one of items 1 to 5, wherein the at least one organic amine comprises benzylamine. (11) The method according to any one of items 1 to 10, wherein the transition metal oxide nanoparticles have an average particle size of 100 nanometers or less. (12) The method according to any one of items 1 to 10, wherein the transition metal oxide nanoparticles have an average particle size of 40 nanometers or less. (13) A surface-modified nanoparticle composition comprising surface-functionalized transition metal oxide nanoparticles, wherein each of the surface-functionalized transition metal oxide nanoparticles comprises a transition metal oxide core having a surface layer thereon, the surface layer being of formula R 1 -CO 2 - (In the formula, R 1 A bonded organic carboxylate represented by a hydrocarbyl group having 6 to 30 carbon atoms, and formula R 2 R 3 NH 2 + (In the formula, R 2 R represents a hydrocarbyl group having 6 to 30 carbon atoms. 3 A surface-modified nanoparticle composition comprising at least one organic ammonium cation represented by H or an alkyl group having 1 to 4 carbon atoms. (14) The surface-modified nanoparticle composition according to item 13, wherein each of the transition metal oxide cores comprises at least one of titanium oxide, zirconium oxide, or cerium oxide. (15) The surface-modified nanoparticle composition according to item 13, wherein each of the transition metal oxide cores comprises at least one of titanium oxide, zirconium oxide, or cerium oxide. (16)R 1 A surface-modified nanoparticle composition according to any one of items 13 to 15, wherein represents a hydrocarbyl group having 6 to 18 carbon atoms. (17)R 1 A surface-modified nanoparticle composition according to any one of items 13 to 15, wherein represents a hydrocarbyl group having 10 to 12 carbon atoms. (18)R 2 A surface-modified nanoparticle composition according to any one of items 13 to 17, wherein represents a hydrocarbyl group having 6 to 18 carbon atoms. (19)R 2 A surface-modified nanoparticle composition according to any one of items 13 to 17, wherein represents a hydrocarbyl group having 7 to 10 carbon atoms. (20)R 3 A surface-modified nanoparticle composition according to any of items 13 to 19, wherein H is present. (21) The surface-modified nanoparticle composition according to any one of items 13 to 20, wherein the at least one organic ammonium cation comprises at least one of benzylammonium, n-octylammonium, or 2-ethylhexylammonium. (22) The surface-modified nanoparticle composition according to any one of items 13 to 20, wherein the at least one organic ammonium cation comprises benzylammonium. (23) The surface-modified nanoparticle composition according to any one of items 13 to 22, wherein the transition metal oxide nanoparticles have an average particle size of 100 nanometers or less. (24) The surface-modified nanoparticle composition according to any one of items 13 to 22, wherein the transition metal oxide nanoparticles have an average particle size of 40 nanometers or less. (25) A curable composition comprising a surface-modified nanoparticle composition according to any one of items 13 to 24, at least one curable monomer, and a curing agent. (26) The curable composition according to item 25, wherein the at least one curable monomer comprises at least one (meth)acrylic monomer, and the curing agent comprises a free radical initiator. (27) The curable composition according to item 26, wherein the free radical initiator comprises a free radical photoinitiator. (28) An article comprising a substrate, wherein the substrate has a layer thereon of at least partially cured curable composition according to any of items 25 to 27.

Claims

1. A method for producing surface-functionalized transition metal oxide nanoparticles, 3. To provide a sol containing transition metal oxide nanoparticles dispersed in an aqueous liquid medium having a pH of 3.5 or less and stabilized with at least one mineral acid, The sol is combined with an extractant composition comprising at least one carboxylic acid, at least one organic amine, and a water-immiscible organic solvent. Each of the at least one carboxylic acid is independently of formula R １ -CO ２ H (wherein, R １ It is represented by a hydrocarbyl group having 6 to 30 carbon atoms. Each of the at least one organic amines is a member of formula R ２ R ３ NH (wherein, R ２ R is a hydrocarbyl group having 6 to 30 carbon atoms. ３ (where is represented by H, or an alkyl group having 1 to 4 carbon atoms), and the at least one organic amine is present in an amount sufficient to neutralize the acid present in the sol, thereby forming a separate separable aqueous phase and organic phase. To separate at least a portion of the organic phase from the aqueous phase, and then to at least partially remove the water-immiscible organic solvent from the separated organic phase, to obtain at least a portion of the surface-functionalized transition metal oxide nanoparticles, Methods that include...

2. The method according to claim 1, wherein the transition metal oxide nanoparticles include at least one of titanium oxide, zirconium oxide, or cerium oxide.

3. R ２ The method according to claim 1, wherein is a hydrocarbyl group having 6 to 18 or 7 to 10 carbon atoms.

4. A surface-modified nanoparticle composition comprising surface-functionalized transition metal oxide nanoparticles, each of the surface-functionalized transition metal oxide nanoparticles comprising a respective transition metal oxide core having a surface layer thereon, each of the respective transition metal oxide cores comprising at least one of titanium oxide or cerium oxide, and the surface layer having the formula R １ -CO ２ － (wherein R １ is a hydrocarbyl group having 6 to 30 carbon atoms), a bonded organic carboxylate represented thereby, and a formula R ２ R ３ NH ２ ＋ (wherein R ２ represents a hydrocarbyl group having 6 to 10 carbon atoms, and R ３ represents H or an alkyl group having 1 to 4 carbon atoms), a surface-modified nanoparticle composition comprising at least one organic ammonium cation represented thereby.

5. R １ The surface-modified nanoparticle composition according to claim 4, wherein represents a hydrocarbyl group having 10 to 12 carbon atoms.

6. R ３ The surface-modified nanoparticle composition according to claim 4 or 5, wherein is H.

7. The surface-modified nanoparticle composition according to any one of claims 4 to 6, wherein the at least one organic ammonium cation comprises at least one of benzylammonium, n-octylammonium, or 2-ethylhexylammonium.

8. The surface-modified nanoparticle composition according to any one of claims 4 to 7, wherein the transition metal oxide nanoparticles have an average particle size of 100 nanometers or less or 40 nanometers or less.

9. A curable composition comprising a surface-modified nanoparticle composition according to any one of claims 4 to 8, at least one curable monomer, and a curing agent.

10. An article comprising a base material, wherein the base material has a layer disposed thereon of at least partially cured curable composition according to claim 9.

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