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EP-4555021-B1 - UV-CURABLE COATINGS HAVING HIGH REFRACTIVE INDEX

EP4555021B1EP 4555021 B1EP4555021 B1EP 4555021B1EP-4555021-B1

Inventors

  • GRIGORENKO, Nikolay A
  • OSWALD, Andre

Dates

Publication Date
20260513
Application Date
20230705

Claims (15)

  1. A coating composition, especially a UV-Vis curable coating composition, comprising i) single or mixed metal oxide nanoparticles, wherein the volume average diameter (D v 50) of the metal oxide nanoparticles is in the range of 1 to 20 nm, ii) one or more monomers having at least three thiol groups (-SH) at the terminal end (the first monomer), iii) optional one or more monomers having at least two functional groups at the terminal end being capable of reacting with the thiol groups and a spacer group between the at least two functional groups (the second monomer), iv) one, or more solvents.
  2. The coating composition according to claim 1, wherein the first monomer is a compound of formula (trithiocyanuric acid).
  3. The coating composition according to claim 1, or 2, wherein the second monomer is selected from bis(4-methacryloylthiophenyl)sulfide, dipropylene glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate, cyclohexanediol diacrylate, cyclohexanediol dimethacrylate, cyclohexanedimethanol diacrylate, cyclohexanedimethanol dimethacrylate, (ethoxylated)neopentyl glycol diacrylate, (propoxylated)neopentyl glycol diacrylate, (ethoxylated)neopentyl glycol dimethacrylate, (propoxylated)neopentyl glycol dimethacrylate, trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), ethoxylated trimethylolpropane triacrylates, ethoxylated trimethylolpropane trimethacrylates, propoxylated trimethylolpropane triacrylates, propoxylated trimethylolpropane trimethacrylates, ethoxylated glycerol triacrylates, ethoxylated glycerol trimethacrylates, propoxylated glycerol triacrylates, propoxylated glycerol trimethacrylates, bistrimethylolpropane tetraacrylate, bistrimethylolpropane tetramethacrylate, ethoxylated bistrimethylolpropane tetraacrylates, propoxylated bistrimethylolpropane tetraacrylates, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, ethoxylated pentaerythritol tetraacrylates, ethoxylated pentaerythritol tetramethacrylates, propoxylated pentaerythritol tetraacrylates, propoxylated pentaerythritol tetramethacrylates, dipentaerythritol hexaacrylate, ethoxylated dipentaerythritol hexaacrylates, propoxylated dipentaerythritol hexaacrylates and mixtures thereof.
  4. The coating composition according to any of claims 1 to 3, wherein the solvent is selected from C 2 -C 4 alcohols, especially ethanol, 1-propanol and isopropanol; ketones, especially acetone, 2-butanone, 2-pentanone, 3-pentanone, cyclopentanone and cyclohexanone; ether alcohols, especially 1-methoxy-2-propanol; mixtures thereof and their mixtures with esters, especially ethyl acetate, 1-propyl acetate, isopropyl acetate and butyl acetate.
  5. The coating composition according to any of claims 1 to 4, wherein the single or mixed metal oxide nanoparticles are titanium dioxide nanoparticles, which have a volume average diameter (D v 50) in the range of 1 to 10 nm, preferably 1 to 5 nm.
  6. The coating composition according to any of claims 1 to 5, wherein the nanoparticles comprise at least one volatile surface-modifying compound selected from ethanol and acetylacetone and mixtures thereof, wherein the total amount of volatile surface-modifying compounds is in the range of from 10 to 50 % by weight, especially from 10 to 40 % by weight, very especially from 15 to 35 % by weight based on the amount of metal oxide nanoparticles.
  7. The coating composition according to any of claims 1 to 6, wherein the single, or mixed metal oxide nanoparticles are titanium dioxide nanoparticles and are obtained by a process comprising the following steps: a) preparing a mixture, comprising a metal alkoxide of formula Ti(OR 12 ) 4 (Xa), a solvent, HCl and water, wherein R 12 is C 1 -C 4 alkyl, preferably methyl, ethyl, n-propyl, iso-propyl and n-butyl; b1) heating the mixture to a temperature of from 80°C to 100 °C; b2) separating the obtained TiO 2 nanoparticles from the mixture; b3) resuspending the TiO 2 nanoparticles in a C 1 -C 4 alcohol, or a mixture of C 1 -C 4 alcohols; b4) optionally treating the TiO 2 nanoparticles with a β-diketone(s), or salt(s) thereof; c1) treating the TiO 2 nanoparticles with a base; c2) optionally treating the TiO 2 nanoparticles with a β-diketone(s), or salt(s) thereof; c3) optionally treating the TiO 2 nanoparticles with a compound of formula Me'(OR 20' ) z (VII), or mixtures thereof; and c4) filtering the mixture to obtain the dispersion of TiO 2 nanoparticles, wherein R 20' is a C 1 -C 8 alkyl group, preferably a C 1 -C 4 alkyl group; Me' is selected from Zn (II), In (III), Sc (III), Y (III), La (III), Ce (IV), Ti (III), Ti (IV), Zr (IV), Hf (IV), Sn (IV), V (IV), Nb (V) and Ta (V), preferably Ti (IV), Zr (IV), Sn (IV), Nb (V) and Ta (V); and z equals to the oxidation state of metal; wherein the solvent comprises at least one ether group and one alcohol group; the ratio of moles of water to total moles of Me and Me' is in the range 3:1 to 5:1, more preferably 3.2:1 to 4.5:1, especially 3.5:1 to 4.5:1; the ratio of moles of HCl to the moles of titanium is in the range 1:1 to 0.3:1, preferably 0.8:1 to 0.35:1, especially 0.7:1 to 0.4:1.
  8. The coating composition according to any of claims 1 to 7, comprising i) 3 to 50 % by weight of the single or mixed metal oxide nanoparticles, ii) 0.15 to 10 % by weight of the one or more monomers having a triazine ring and at least three thiol groups (-SH) at the terminal end (the first monomer), iii) 0 to 30 % by weight of the one or more monomers having at least two functional groups at the terminal end being capable of reacting with the thiol groups and a spacer group between the at least two functional groups (the second monomer), and iv) 20 to 96.9 % by weight of the one, or more solvents; based on total weight of component(s) i), ii), iii) and iv).
  9. A coating having a refractive index of greater than 1.7, especially of greater than 1.8, very especially of greater than 1.9, obtainable from the coating composition according to any of claims 1 to 8.
  10. The coating according to claim 9 having a thickness of from 0.01 to 0.50 micrometer, preferably 0.02 to 0.40 micrometer, more preferably 0.03 to 0.30 micrometer, most preferably 0.04 to 0.25 micrometer after drying and UV curing; or the coating according to claim 9 having a thickness of from 0.10 to 30.0 micrometer, preferably 0.20 to 20.0 micrometer, more preferably 0.30 to 10 micrometer, most preferably 0.50 to 6.0 micrometer after drying and UV curing.
  11. A method for forming a coating having a high refractive index on a substrate comprising the steps of: a) providing a substrate, preferably carrying a surface relief nano- and/or microstructure; b) applying the coating composition according to any of claims 1 to 8 to the substrate by means of wet coating, or printing; c) removing the solvent; and d) exposing the dry coating to actinic radiation, especially UV-light.
  12. A security, or decorative element, comprising a substrate, which may contain indicia or other visible features in or on its surface, and on at least part of the said substrate surface, a coating according to claim 9, or 10; or a coating obtained according to the method according to claim 11.
  13. A method for forming a surface relief micro- and nanostructure on a substrate comprising the steps of: a) forming a surface relief micro- and/or nanostructure on a discrete portion of the substrate; b) depositing the coating composition according to any of claims 1 to 8 on at least a portion of the surface relief micro- and/or nanostructure; c) removing the solvent; and d) curing the dry coating by exposing it to actinic radiation, especially UV-light; or a method for forming a surface relief micro- and/or nanostructure on a substrate comprising the steps of a') providing a sheet of base material, said sheet having an upper and lower surface; b') depositing the coating composition according to any of claims 1 to 8 on at least a portion of the upper surface; c') removing the solvent; d') forming a surface relief micro- and/or nanostructure on at least a portion of the coating composition; e') curing the dry coating obtained in step d') by exposing it to actinic radiation, especially UV-light; or a method for forming a surface relief micro- and/or nanostructure on a substrate comprising the steps of a") providing a sheet of base material, said sheet having an upper and lower surface; b") depositing the coating composition according to any of claims 1 to 8 on at least a portion of the upper surface; c") removing the solvent; d") forming a surface relief micro- and/or nanostructure on at least a portion of the coating composition, such that the micro- or nanostructure is formed, at least partially, in the base material. e") curing the dry coating obtained in step d") by exposing it to actinic radiation, especially UV-light.
  14. The method according to claim 13, wherein step a) comprises a1) applying a curable compound to at least a portion of the substrate; a2) contacting at least a portion of the curable compound with surface relief micro- and nanostructure forming means; and a3) curing the curable compound.
  15. Use of the coating composition according to any of claims 1 to 8 for coating diffractive optical elements (DOEs), holograms, manufacturing of optical waveguides and solar panels, light outcoupling layers for display and lighting devices, high dielectric constant (high-k) gate oxides and interlayer high-k dielectrics, anti-reflection coatings, etch and CMP stop layers, optical thin film filters, optical diffractive gratings and hybrid thin film diffractive grating structures, high refractive index abrasion-resistant coatings, in protection and sealing (OLED), or organic solar cells.

Description

The present invention relates to coating compositions, comprising i) single or mixed metal oxide nanoparticles, wherein the volume average diameter (Dv50) of the metal oxide nanoparticles is in the range of 1 to 20 nm; ii) one or more monomers having at least three thiol groups (-SH) at the terminal end (the first monomer), and iii) optional one or more monomers having at least two functional groups at the terminal end being capable of reacting with the thiol groups and a spacer group between the at least two functional groups (the second monomer),iv) one, or more solvents; coatings obtained therefrom and the use of the compositions for coating surface relief micro- and nanostructures (e.g. holograms), manufacturing of optical waveguides, solar panels, light outcoupling layers for display and lighting devices and anti-reflection coatings. Coatings obtained from the coating composition have a high refractive index and holograms are bright and visible from any angle, when the coating compositions are applied to them. TECHNICAL BACKGROUND JP2020029542A (US2020/062927) relates to an organic-inorganic composite composition comprising a polymer (A) having a triazine ring structure in a polymer main chain structure; inorganic fine particles (B); and a surface treatment agent having a predetermined triazine ring structure where the inorganic fine particles (B) have a number-based median size (Dn50) of 1 nm or more and 20 nm or less, and R1 is carboxy, phosphato, sulfo, or alkyl, alkenyl, alkynyl, aryl, aralkyl, or amino (all optionally substituted); a molded product and an optical component comprising the organic-inorganic composite composition. US10717866B2 (US2018/0244915) relates to an organic-inorganic hybrid composition comprising a polymer (A) including a triazine ring structure represented by General Formula (1) in a polymer main chain structure: wherein, in the formula, R1 is a substituted or unsubstituted alkyl group, aryl group, aralkyl group, amino group, arylamino group, alkylthio group, or arylthio group); an inorganic particulate (B); anda surface-treatment agent (C) including an acidic functional group,wherein the polymer (A) is a thermoplastic polymer having a glass transition temperature (Tg),a number median diameter (Dn50) of the inorganic particulate (B) is greater than or equal to about 1 nm and less than or equal to about 20 nm; and an article and an optical component including the organic-inorganic hybrid composition. US11312840B2 relates to an organic-inorganic hybrid composition, comprising: a polymer having a triazine ring structure in a main chain of the polymer (A);an inorganic particulate (B), such as, for example, zirconium oxide, a titanium oxide, a barium titanate, a strontium titanate, a zinc oxide, a gallium phosphide, a cerium oxide, a niobium oxide, or a combination thereof; anda surface-treating agent having a triazine ring structure represented by Formula (1) (C): wherein, in Formula (1), R1 is a carboxyl group, a phosphoric acid group, a sulfo group, or a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted amino group,wherein a number median diameter (Dn50) of the inorganic particulate (B) is greater than or equal to about 1 nanometer and less than or equal to about 20 nanometer, wherein "" is a linking point to an adjacent atom; an article and an optical component including the organic-inorganic hybrid composition. US10197820B2 provides quantum dots passivated by oligomers or polymers which are formed by a reaction of a first monomer having at least three thiol groups (-SH) at the terminal end with a second monomer having at least two functional groups at the terminal end that can react with the thiol groups, and a spacer group between the at least two functional groups. US20190338092A1 relates to flexible color filters and methods of manufacturing flexible color filters. An example flexible color filter comprises a transparent flexible substrate comprising a thermoset thiol-click polymer. US20210403731 relates to a material composition of a light out-coupling lens for a quantum dot display panel, comprising: trimethylolpropane tris(3-mercaptopropionate);triethyleneglycol divinyl ether; andan ultraviolet free-radical initiator;wherein a molar ratio of trimethylolpropane tris(3-mercaptopropionate) to triethyleneglycol divinyl ether is 2:3, the material composition is cured by an ultraviolet light to form the light out-coupling lens, a diameter of a bottom of the light out-coupling lens ranges from 30 to 100 micrometers, and a height of the light out-coupling lens ranges from 20 to 80 micrometers. WO2019/016136 discloses surface functionalized titanium dioxide nanoparticles treated with a) a phosphonate of formula , or a mixture of phosphonates of formula (I), wherein R1 and