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US-12617898-B2 - Compositions and coatings for UV-VIS and IR transparent thin films

US12617898B2US 12617898 B2US12617898 B2US 12617898B2US-12617898-B2

Abstract

Compositions and coatings for thin films designed to protect surfaces and windows from environmental abrasion (e.g., sand, dust, and rubbing) that are transparent in visual and infrared wavelengths are disclosed. The compositions comprise thiol-containing copolymers comprising: (1) 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol; and (2) a multifunctional terminally unsaturated hydrocarbon monomer; wherein (1) and (2) are combined to form a UV curable crosslinked thermoset polymer network and no particulate fillers are added to the composition. The films exhibit a specular transmission of greater than 70% in the visual spectrum at about 400-700 nm, and IR wavelengths at about 4-5 μm, and about 7.5-12 μm when applied to a surface of a substrate in a coating thickness of about 1-500 μm. A method for making the films involving an UV initiated thiol-ene curing mechanism is also provided.

Inventors

  • Andrew P. Nowak
  • Erik Daniel Crenshaw
  • Marcos Pantoja
  • Jeffrey Daniel Britton

Assignees

  • THE BOEING COMPANY

Dates

Publication Date
20260505
Application Date
20231011

Claims (20)

  1. 1 . A polymer composition comprising: a thiol-containing copolymer which comprises (1) 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol; and (2) at least one multifunctional terminally unsaturated hydrocarbon monomer; wherein (1) and (2) are combined to form a UV curable crosslinked thermoset polymer network, and particulate fillers are not added to the composition; and wherein the composition exhibits a specular transmission of greater than 70% in a visual spectrum at about 400-700 nm, and IR wavelengths at about 4-5 μm, and about 7.5-12 μm when applied to a surface of a substrate in a coating thickness of about 1 to 500 μm.
  2. 2 . The polymer composition according to claim 1 , wherein the thiol-containing copolymer further comprises (3) at least one multifunctional thiol-terminated hydrocarbon monomer comprising a hydrocarbon interior.
  3. 3 . The polymer composition according to claim 1 , further comprising one or more of a solvent, an initiating agent, a pigment, a dye, an antioxidant, and a UV stabilizer.
  4. 4 . The polymer composition according to claim 2 , wherein the multifunctional thiol-terminated hydrocarbon monomer is 2-[2,4-bis(2-mercaptoethyl)cyclohexyl]ethanethiol, 1,3,5, tris(2-mercaptoethyl)cyclohexane or α,ω-thiol-terminated hydrogenated polybutadiene, and mixtures thereof.
  5. 5 . The polymer composition according to claim 1 , wherein the at least one multifunctional terminally unsaturated hydrocarbon monomer is 1,2,4-trivinylcyclohexane.
  6. 6 . The polymer composition according to claim 1 , wherein the at least one multifunctional terminally unsaturated hydrocarbon monomer comprises 1,2,4-trivinylcyclohexane and polybutadiene.
  7. 7 . The polymer composition according to claim 2 , wherein the at least one multifunctional thiol-terminated hydrocarbon monomer is 2-[2,4-bis(2-mercaptoethyl)cyclohexyl]ethanethiol, and the at least one multifunctional terminally unsaturated hydrocarbon monomer comprises 1,2,4-trivinylcyclohexane and polybutadiene.
  8. 8 . A film comprising a polymer composition which comprises: a thiol-containing copolymer which comprises (1) 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol; and (2) at least one multifunctional terminally unsaturated hydrocarbon monomer; wherein (1) and (2) are combined to form a UV curable crosslinked thermoset polymer network and particulate fillers are not added to the composition; wherein said polymer composition is applied to a surface of a substrate and cured by UVC light or UV light to form the film; and wherein the film exhibits a specular transmission of greater than 70% in a visual spectrum at about 400-700 nm, and IR wavelengths at about 4-5 μm, and about 7.5-12 μm when applied to a surface of a substrate in a coating thickness of about 1 to 500 μm.
  9. 9 . The film according to claim 8 , wherein the thiol-containing copolymer further comprises (3) at least one multifunctional thiol-terminated hydrocarbon monomer comprising a hydrocarbon interior.
  10. 10 . The film according to claim 8 , wherein the at least one multifunctional terminally unsaturated hydrocarbon monomer is 1,2,4-trivinylcyclohexane.
  11. 11 . The film according to claim 8 , wherein the at least one multifunctional terminally unsaturated hydrocarbon monomer comprises 1,2,4-trivinylcyclohexane and polybutadiene.
  12. 12 . The film according to claim 9 , wherein the thiol-containing copolymer comprises 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol and (2-[2,4-bis(2-mercaptoethyl)cyclohexyl]ethanethiol), and the at least one multifunctional terminally unsaturated hydrocarbon monomer comprises 1,2,4-trivinylcyclohexane and polybutadiene.
  13. 13 . The film according to claim 9 , wherein the film is further cured by exposure to electron beam radiation.
  14. 14 . The film according to claim 9 , wherein the polymer composition applied to the surface of the substrate is cured by UVC light or UV light without addition of an initiating agent.
  15. 15 . The film according to claim 9 , wherein the polymer composition applied to the surface of the substrate is cured by UVC light or UV light with addition of a photoinitiator.
  16. 16 . A method for making a film comprising: providing a thiol-containing copolymer which comprises 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol; providing at least one multifunctional terminally unsaturated hydrocarbon monomer; dissolving the thiol-containing copolymer which comprises 10-(3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl) decane-1-thiol and the at least one multifunctional terminally unsaturated hydrocarbon monomer in a solvent and forming a reaction mixture; depositing the reaction mixture onto a surface of a substrate to form a coating; and curing the coating with UVC light or UV light to form the film.
  17. 17 . The method according to claim 16 , wherein the thiol-containing copolymer further comprises a multifunctional thiol-terminated hydrocarbon monomer.
  18. 18 . The method of claim 16 , wherein the thiol-containing copolymer further comprises a monofunctional thiol-terminated hydrocarbon monomer or a monofunctional thiol-terminated hydrocarbon monomer.
  19. 19 . The method according to claim 16 , further comprising, after forming a reaction mixture, partially reacting the thiol-containing copolymer and the at least one multifunctional terminally unsaturated hydrocarbon monomer in the reaction mixture by exposure to UVC light.
  20. 20 . The method according to claim 16 , further comprising exposing the film to electron beam radiation.

Description

TECHNICAL FIELD The present disclosure generally relates to compositions, coatings, and methods for making thin films that are transmissive to radiation in the visual and the infrared wavelengths. BACKGROUND Progress in the field of autonomous vehicles has been maturing rapidly. A key to this technology is a diverse collection of sensors acquiring data across the visual, near IR (LIDAR) and radar bands of the spectrum. While the present state of the art is noteworthy, greater reliability and safety are continually being sought. To be truly reliable, the system should have the capability of detecting and classifying any object over a wide range of distances. The incorporation of thermal imaging into the sensor suite through the addition of a passive signal is being considered in sensor packages. Protection of such sensors is important to ensure reliable long-term performance under real world conditions. Imaging windows in infrared systems (3-15 μm) typically employ chalcogenides (ZnS, ZnSe), semiconductors (Ge), or oxides (Al2O3). These materials are characteristically brittle with their behavior demonstrating low fracture toughness. Consequently, they are susceptible to damage from high-speed rain or solid particles when these windows are exposed to the environment. As a result, there exists a need for affordable, easily manufactured, and installed visually and IR transparent films for the protection of materials susceptible to environmental damage. SUMMARY In accordance with one or more examples, the present disclosure provides a polymer composition comprising: a thiol-containing copolymer which comprises (1) f; and (2) at least one multifunctional terminally unsaturated hydrocarbon monomer. Components (1) and (2) are combined to form a UV curable crosslinked thermoset polymer network, and particulate fillers are not added to the composition. The compositions of the present disclosure exhibit a specular transmission of greater than 70% in a visual spectrum at about 400-700 nm, and IR wavelengths at about 4-5 μm, and about 7.5-12 μm when applied to a surface of a substrate in a coating thickness of about 1 to 500 μm. In some examples, the at least one multifunctional terminally unsaturated hydrocarbon monomer can be 1,2,4-trivinylcyclohexane, or polybutadiene, and mixtures thereof. The polymer compositions may further comprise (3) at least one multifunctional thiol-terminated hydrocarbon monomer comprising a hydrocarbon interior. The multifunctional thiol-terminated hydrocarbon monomer may be 2-[2,4-bis(2-mercaptoethyl)cyclohexyl]ethanethiol, 1,3,5-tris(2-mercaptoethyl)cyclohexane, or α,ω-thiol-terminated hydrogenated polybutadiene, and mixtures thereof. In an example, the thiol-containing copolymer of the present disclosure comprises 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol and 1,2,4-trivinylcyclohexane. In another example, the thiol-containing copolymer comprises 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol and 1,2,4-trivinylcylcohexane and polybutadiene. In yet another example, the thiol-containing copolymer comprises 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol, 2-[2,4-bis(2-mercaptoethyl)cyclohexyl]ethanethiol, 1,2,4-trivinylcyclohexane, and polybutadiene. The present disclosure also provides a film comprising a polymer composition which comprises: a thiol-containing copolymer which comprises (1) 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol; and (2) at least one multifunctional terminally unsaturated hydrocarbon monomer. Components (1) and (2) are combined to form a UV curable crosslinked thermoset polymer network and particulate fillers are not added to the composition. The polymer composition is applied to a surface of a substrate and cured by UVC light or UV light to form a film. Films of the present disclosure exhibit a specular transmission of greater than 70% in a visual spectrum at about 400-700 nm, and IR wavelengths at about 4-5 μm, and about 7.5-12 μm when applied to a surface of a substrate in a coating thickness of about 1 to 500 μm. The films of the present disclosure may be further cured by exposure to electron beam radiation. In some examples, the polymer composition may be applied to the surface of the substrate and cured by UVC light or UV light without addition of an initiating agent. In other examples, the polymer composition applied to the surface of the substrate is cured by UVC light or UV light with the addition of a photoinitiator. The present disclosure further provides a method for making a film comprising: providing a thiol-containing copolymer which comprises 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol; providing at least one multifunctional terminally unsaturated hydrocarbon monomer; dissolving the thiol-containing copolymer which comprises 10-3-butyl-2-hexyl-6-(9-mercaptononyl)cyclohexyl)decane-1-thiol and the at least one multifunctional terminally unsaturated hydrocarbon m