Ultraviolet C-emitting disinfection device and method of use thereof

Abstract

The device includes a housing that is substantially opaque to ultraviolet radiation having a wavelength between 280 nm and 400 nm, at least one window defined within the housing, the window including a UV-C radiation bandpass mirror film having multiple interleaved first and second optical layers that collectively transmit at least UV-C radiation with wavelengths less than 100 nm to 280 nm and are non-transmissive to UV-A and UV-B radiation with wavelengths between 280 nm and 400 nm, and an ultraviolet radiation source positioned within the housing, the ultraviolet radiation source capable of emitting ultraviolet radiation at one or more wavelengths between 100 nm and 400 nm. The device optionally further includes an ultraviolet mirror film positioned within the housing to reflect ultraviolet radiation emitted by the ultraviolet radiation source. Methods of disinfecting materials are also disclosed.

Description

[Background technology]

[0001] Ultraviolet (UV) light or ultraviolet radiation is useful for initiating free radical chemical reactions, for example, in the manufacture of coatings, adhesives, and various (co)polymer materials. Ultraviolet radiation can also be useful for disinfecting surfaces such as bandages, membranes, and filtration media, as well as for disinfecting air and liquids (e.g., water). Disinfecting air and water is of paramount importance to human health and the prevention of infectious diseases. As pathogens mutate and develop antibiotic resistance, preventing the transmission and spread of disease is becoming increasingly important, especially in high-risk environments and populations.

[0002] Hospitals currently disinfect patient rooms, operating rooms, and hospital surfaces using strong chemicals that can produce unpleasant odors and have undesirable health effects. Public restrooms also have well-known surfaces that can transmit disease and bacteria, and are generally disinfected using chemical disinfection methods. In addition to patient rooms and public restrooms, all other public areas, including public transport such as buses, trains, and airplanes, as well as public schools, restaurants, grocery stores, and retail stores, require regular disinfection to prevent the spread of disease. The availability and speed of human movement on a global scale increases the risk of disease spreading rapidly on surfaces that are not regularly disinfected, which could lead to epidemics or even pandemics.

[0003] UV-C radiation (i.e., electromagnetic radiation emission at one or more wavelengths in the range of 100 nanometers to 280 nanometers) can effectively inactivate or kill prokaryotic and eukaryotic microorganisms, including bacteria, viruses, spores, fungi, and molds. Even bacterial strains that have developed resistance to one or more antibiotics remain susceptible to UV-C radiation exposure. Some examples of pathogens that are particularly targeted for UV-C irradiation disinfection include hospital-acquired infections (e.g., C. diff, E. coli, methicillin-resistant Staphylococcus aureus [MRSA], Klebsiella, influenza, mycobacteria, and Enterobacteria), waterborne and soilborne infections (e.g., Giardia, Legionella, and Campylobacter), and airborne infections (e.g., influenza, pneumonia, and tuberculosis). [Overview of the Initiative]

[0004] UV radiation emitted at certain wavelengths can be harmful to humans and animals to varying degrees. Unfortunately, many commercially available ultraviolet radiation sources capable of emitting UV-C radiation, which is useful for achieving disinfection, also emit UV-A radiation (i.e., electromagnetic radiation emission at one or more wavelengths in the range of 315 nanometers to 400 nanometers) and / or UV-B radiation (i.e., electromagnetic radiation emission at one or more wavelengths in the range of 280 nanometers to 315 nanometers). UV-A and UV-B radiation differ in how they affect the skin, but both can be harmful. Unprotected, prolonged exposure to UV-A and UV-B radiation can cause genetic abnormalities or mutations that damage DNA in human skin cells, potentially leading to premature aging, wrinkles, and even skin cancer, as well as eye damage, such as cataracts and eyelid cancer.

[0005] Thus, the present disclosure relates to a disinfection device that incorporates a low-cost, commercially available broadband UV light source, and that incorporates one or more multilayer UV-C mirror films that function as a bandpass filter that transmits a substantial amount of UV-C radiation useful for disinfection while reflecting substantially all UV-A radiation and UV-B radiation that can have undesirable effects on health. Such devices are particularly useful for portable or hand-held disinfection applications because the UV-C radiation emitted by the disinfection device can be used without causing significant adverse health effects in the presence of humans and animals.

[0006] Therefore, in one aspect, the present disclosure describes a device that includes a housing that is substantially impermeable to ultraviolet radiation having wavelengths between 280 nm and 400 nm, at least one window defined within the housing, and an ultraviolet radiation source positioned within the housing. The ultraviolet radiation source is capable of emitting ultraviolet radiation having one or more wavelengths between 100 nm and 400 nm. The window includes a UV-C radiation bandpass mirror film that includes a number of alternating first optical layers and second optical layers that collectively transmit UV-C radiation having wavelengths from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm. The UV-C radiation bandpass mirror film substantially does not transmit UV-A radiation and UV-B radiation having wavelengths between 280 nm and 400 nm.

[0007] The present disclosure also describes a multilayer UV-C mirror film that functions as a bandpass filter for reflecting UV-C radiation from a broadband UV light source back within the UV radiation impermeable housing of a disinfection device for use within the disinfection device to reflect UV-C radiation from the broadband UV light source to a window within the disinfection device that is covered with the multilayer UV-C mirror film to enable the emission of a substantial amount of UV-C radiation useful for disinfecting a surface while reflecting substantially all UV-A radiation and UV-B radiation that can have undesirable effects on health back within the housing.

[0008] Therefore, in some particularly advantageous embodiments, the device further includes an ultraviolet mirror film positioned inside the housing to reflect the ultraviolet radiation emitted by the ultraviolet radiation source. The ultraviolet mirror film includes a number of alternately arranged first optical layers and second optical layers that collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of the incident UV-C ultraviolet radiation in a wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of the incident ultraviolet radiation in a wavelength range from greater than 230 nanometers, greater than 235 nm, or greater than 240 nm to 400 nanometers. At least 50, 60, 70, 80, 90, or 95 percent of the ultraviolet radiation having a wavelength of at least 230 nanometers to 400 nanometers that is transmitted through the ultraviolet mirror is absorbed by the ultraviolet mirror film.

[0009] Furthermore, since some surfaces being disinfected with ultraviolet radiation (e.g., (co)polymer surfaces) may need to be protected even from UV-C ultraviolet light, the present disclosure also relates to a UV-C mirror protection film, which can protect the underlying surface to which the UV mirror protection film is applied from damage due to the effects of UV irradiation exposure by reflecting UV-C radiation and optionally one or more of UV-A radiation and UV-B radiation.

[0010] Therefore, in another embodiment, the present disclosure describes a UV-C mirror film comprising a substrate made of a fluoropolymer, a multilayer optical film disposed on the main surface of the substrate, comprising at least a plurality of alternatingly arranged first and second optical layers that collectively reflect at least 30 percent of incident ultraviolet radiation over a wavelength reflection bandwidth of at least 30 nanometers in the wavelength range of at least 100 nanometers to 280 nanometers, or optionally in the wavelength range of at least 240 nm to 400 nm, at at least one incident light angle of 0°, 30°, 45°, 60°, or 75°, in the wavelength range of at least 30 nanometers, and a heat-sealable adhesive layer disposed on the main surface of the multilayer optical film opposite to the substrate.

[0011] In any of the embodiments described above, the fluoropolymer is a (co)polymer comprising tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, perfluoroalkoxyalkane, or a combination thereof. In some such embodiments, the heat-sealable adhesive layer comprises a (co)polymer. In any of the embodiments described above, the (co)polymer is selected from olefin (co)polymers, (meth)acrylate (co)polymers, urethane (co)polymers, fluoropolymers, silicone (co)polymers, or a combination thereof. In certain such embodiments, the (co)polymer is an olefin (co)polymer selected from low-density polyethylene, linear low-density polyethylene, ethylene vinyl acetate, polyethylene methyl acrylate, polyethylene octene, polyethylene propylene, polyethylene butene, polyethylene maleic anhydride, polymethylpentene, polyisobutene, polyisobutylene, polyethylene propylenediene, cyclic olefin copolymers, and blends thereof.

[0012] In some of the embodiments described above, the (co)polymer has a melting temperature in the range of 110°C to 190°C. In other exemplary embodiments, the (co)polymer has a melting temperature of less than 150°C. In certain such embodiments, the (co)polymer is crosslinked. In some such embodiments, the (co)polymer further comprises an ultraviolet radiation absorber, a hindered amine light stabilizer, an antioxidant, or a combination thereof. In further such embodiments, the ultraviolet radiation absorber is selected from benzotriazole compounds, benzophenone compounds, triazine compounds, or a combination thereof.

[0013] In any of the embodiments of the UV-C mirror film described above, at least a first optical layer comprises at least one polyethylene(co)polymer, and a second optical layer comprises at least one fluoropolymer selected from tetrafluoroethylene(co)polymer, hexafluoropropylene(co)polymer, vinylidene fluoride(co)polymer, hexafluoropropylene(co)polymer, perfluoroalkoxyalkane(co)polymer, or a combination thereof. In some such embodiments, at least one fluoropolymer is crosslinked.

[0014] In any of the embodiments described above, at least the first optical layer comprises at least one of zirconium oxynitride, hafnia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride, and the second optical layer comprises at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica-alumina oxide, or alumina-doped silica.

[0015] In another aspect, the Disclosure describes a method of using a disinfection device according to one of the device embodiments described above to disinfect a surface to a desired degree of disinfection, the method comprising supplying the disinfection device, directing ultraviolet radiation emitted by an ultraviolet radiation source through a UV-C bandpass mirror film, and exposing at least one material to the ultraviolet radiation passing through the UV-C bandpass mirror film for a time sufficient to reach a desired degree of disinfection of the at least one material. The ultraviolet radiation passing through the UV-C bandpass mirror film is in a wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm. The ultraviolet light passing through the UV-C bandpass filter is substantially free of UV-A and UV-B radiation with wavelengths between 280 nm and 400 nm.

[0016] In some currently preferred embodiments, a log2, log3, log4, or greater reduction in the amount of at least one microorganism present on or within the at least one material is achieved by exposing at least one material to ultraviolet radiation passing through a UV-C bandpass mirror film for a period of time sufficient to reach a desired degree of disinfection of the at least one material.

[0017] A variety of unexpected results and benefits have been obtained in the various exemplary embodiments of this disclosure, a partial list of which is given below.

[0018] List of exemplary embodiments Embodiment A: A device, A housing that is substantially impermeable to ultraviolet radiation having wavelengths of 280 nm to 400 nm; and at least one window defined within the housing, which includes a UV-C radiation bandpass mirror film comprising a plurality of alternatingly arranged first and second optical layers that collectively transmit UV-C radiation with wavelengths from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and substantially impermeably transmit UV-A radiation and UV-B radiation with wavelengths of 280 nm to 400 nm; The device comprises an ultraviolet radiation source positioned inside the housing, capable of emitting ultraviolet radiation of one or more wavelengths between 100 nm and 400 nm, and the device optionally allows, An ultraviolet mirror film positioned inside a housing to reflect ultraviolet radiation emitted by an ultraviolet radiation source, which collectively reflects at least 50, 60, 70, 80, 90, or 95 percent of incident UV-C ultraviolet radiation in the wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, to a depth of over 230 nanometers. A device further comprising an ultraviolet mirror film comprising at least a plurality of alternatingly arranged first and second optical layers that collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet radiation in the wavelength range from above 235 nm or above 240 nm to 400 nanometers, wherein at least 50, 60, 70, 80, 90, or 95 percent of ultraviolet radiation having wavelengths of at least 230 nanometers to 400 nanometers transmitted through the ultraviolet mirror is absorbed into the chamber.

[0019] Embodiment B: The device of Embodiment A, wherein the housing has a hollow, non-planar shape, and furthermore, the ultraviolet radiation source is substantially surrounded by the housing.

[0020] Embodiment C: A device of any of the prior embodiments, wherein the ultraviolet radiation source is a germicidal lamp or an excimer lamp.

[0021] Embodiment D: A device of any of the prior embodiments, wherein the UV-C radiation bandpass mirror film comprises at least a first optical layer comprising at least one of zirconium oxynitride, hafnia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride, and at least a second optical layer comprising at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica-alumina oxide, or alumina-doped silica.

[0022] Embodiment E: The device of Embodiment D, wherein at least a first optical layer comprises at least one of polyvinylidene fluoride or polyethylene tetrafluoroethylene, and at least a second optical layer comprises fluorinated ethylene propylene (FEP), or a copolymer of tetrafluoroethylene, hexafluoropropylene, and polyvinylidene fluoride.

[0023] Embodiment F: A device of any of the prior embodiments, wherein the ultraviolet mirror film is positioned inside the housing.

[0024] Embodiment G: The device of Embodiment F, wherein the ultraviolet mirror film is separated from the ultraviolet radiation source by an air gap.

[0025] Embodiment H: The ultraviolet mirror film is A substrate composed of fluoropolymers, A device according to Embodiment F or Embodiment G, comprising: a multilayer optical film disposed on the main surface of a substrate, comprising at least a plurality of alternately arranged first and second optical layers that collectively reflect incident ultraviolet radiation over a wavelength reflection bandwidth of at least 30 nanometers in a wavelength range of at least 100 nanometers to 400 nanometers, or optionally in a wavelength range of at least 180 nm to less than 280 nm; and optionally an adhesive layer disposed on the main surface of an ultraviolet mirror film.

[0026] Embodiment I: The device of Embodiment H, wherein the fluoropolymer is a (co)polymer comprising tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, perfluoroalkoxyalkane, or a combination thereof.

[0027] Embodiment J: A device of Embodiment H or Embodiment I, wherein at least one first optical layer of a multilayer optical film comprises at least one polyethylene(co)polymer, and the second optical layer comprises at least one fluoropolymer selected from tetrafluoroethylene(co)polymer, hexafluoropropylene(co)polymer, vinylidene fluoride(co)polymer, hexafluoropropylene(co)polymer, perfluoroalkoxyalkane(co)polymer, or a combination thereof, and optionally, at least one fluoropolymer is crosslinked.

[0028] Embodiment K: A device of Embodiment H, I, or Embodiment J, wherein at least one first optical layer of a multilayer optical film comprises at least one of zirconium oxynitride, hafnia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride, and the second optical layer comprises at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica-alumina oxide, or alumina-doped silica.

[0029] Embodiment L: A device of Embodiments H, I, J, or K, wherein at least one first optical layer of a multilayer optical film comprises at least one of polyvinylidene fluoride or polyethylene tetrafluoroethene, and the second optical layer comprises a copolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.

[0030] Embodiment M: A device of Embodiments H, I, J, K, or L, wherein an adhesive layer is present and positioned adjacent to the housing, and further, the adhesive layer contains a (co)polymer.

[0031] Embodiment N: The device of Embodiment M, wherein the adhesive layer further comprises an ultraviolet radiation absorber selected from a benzotriazole compound, a benzophenone compound, a triazine compound, or a combination thereof.

[0032] Embodiment O: A method for disinfecting at least one material, To supply a device according to any of Embodiments A, B, C, D, E, F, G, H, I, J, K, L, M, or Embodiment N, The ultraviolet radiation emitted by the ultraviolet radiation source is directed through a UV-C bandpass mirror film, Exposing at least one material to ultraviolet radiation passing through a UV-C bandpass mirror film for a sufficient time to achieve a desired degree of disinfection of that at least one material, wherein the ultraviolet radiation passing through the UV-C bandpass mirror film has a wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and has a wavelength of 280 nm to 400 nm, UV A method comprising substantially free from UV-A radiation and UV-B radiation, and optionally exposing at least one material to ultraviolet radiation passing through a UV-C bandpass mirror film, the exposure being carried out until a log2, log3, log4, or greater reduction in the amount of at least one microorganism present on or within the at least one material is achieved, compared to the amount of at least one microorganism present before the at least one material was exposed to ultraviolet radiation passing through the UV-C bandpass mirror film.

[0033] Various aspects and advantages of the exemplary embodiments of this disclosure have been summarized. The above “Summary of the Invention” is not intended to describe each illustrated embodiment or all implementations of the particular exemplary embodiments of this disclosure. The following drawings and “Modes for Carrying Out the Invention” illustrate in more detail certain preferred embodiments using the principles disclosed herein. [Brief explanation of the drawing]

[0034] This disclosure can be better understood by considering the following detailed descriptions of various embodiments of this disclosure in relation to the attached figures. [Figure 1] This is a schematic cross-sectional view of an exemplary multilayer optical film used in an exemplary assembly described herein. [Figure 2A] This is a spectral graph of measured absorbance versus wavelength as a function of time for the coated film of Comparative Example 1 described herein. [Figure 2B] This is a spectral graph of measured absorbance versus wavelength as a function of time for the coated film of Comparative Example 2 described herein. [Figure 3A] This is a spectral graph of measured absorbance versus wavelength as a function of time for the UV-C protective film of Substrate Film Example 1 described herein. [Figure 3B] This is another spectral graph of measured absorbance versus wavelength as a function of time for the UV-C protective film of Substrate Film Example 1 described herein. [Figure 3C] This is a spectral graph of measured absorbance versus wavelength as a function of time for the UV-C protective film of Substrate Film Example 2 described herein. [Figure 4] This is a graph of measured light reflectance versus wavelength for the UV-C protective mirror film of Example 1 described herein. [Figure 5] This is a graph of modeled light reflectance versus wavelength for the UV-C protective mirror film of hypothetical example I described herein. [Figure 6] This is a graph of modeled light reflectance versus wavelength for the UV-C protective mirror film of hypothetical example II described herein. [Figure 7] This is a graph of measured light reflectance versus wavelength for the broadband UV-C protective mirror film of Example 3 described herein. [Figure 8] This is a graph of measured light reflectance versus wavelength for the broadband UV-C protective mirror film of Example 4 described herein. [Figure 9] This is a schematic side view of a UV-C disinfection device according to an exemplary embodiment of the present disclosure. [Figure 10] This is a schematic perspective view of another UV-C disinfection device according to an exemplary embodiment of the present disclosure. [Figure 11] This is a schematic side view of a further UV-C disinfection device using a collimated broadband UV light source, according to another exemplary embodiment of the present disclosure. [Figure 12]This flowchart illustrates an exemplary method of using a UV-C disinfection device to disinfect a surface.

[0035] In the drawings, similar reference numerals indicate similar elements. The drawings identified above, which may not be drawn to exact scale, illustrate various embodiments of the present disclosure, but other embodiments are also conceivable, as noted in the "Modes for Carrying Out the Invention." In all cases, the present disclosure describes the disclosures herein not by express limitation, but by exemplary embodiments. It should be understood that numerous other modifications and embodiments included in the scope and spirit of the present disclosure can be conceived by those skilled in the art. [Modes for carrying out the invention]

[0036] With regard to the following glossary of terms that are defined, these definitions shall apply to the entire application unless otherwise explicitly stated in the claims or elsewhere herein.

[0037] Glossary The term "(co)polymer" includes homopolymers and copolymers, as well as homopolymers or copolymers that can be formed in miscible blends, for example by co-extrusion or by reactions including transesterification. The term "copolymer" also includes random copolymers, block copolymers, and star-shaped (e.g., dendritic) copolymers.

[0038] The terms "(meth)acrylic" or "(meth)acrylate" in relation to monomers and oligomers refer to vinyl-functional alkyl esters formed as reaction products of alcohols with acrylic acid or methacrylic acid.

[0039] The term "fluoropolymer" refers to any organic (co)polymer containing fluorine.

[0040] The term "SPOX" refers to silicone poloxamide copolymer.

[0041] The term "incident light" in relation to light refers to light shining onto or hitting a material.

[0042] The term "radiation" refers to electromagnetic radiation unless otherwise specified.

[0043] The term "absorption" refers to the process by which a material converts the energy of light radiation into internal energy.

[0044] The term "absorb" in relation to the wavelength of light encompasses both absorption and scattering, since scattered light is ultimately also absorbed.

[0045] The term "scattering," in relation to the wavelength of light, refers to the process of causing light to deviate from its linear path and travel in various directions with varying intensities.

[0046] The term "reflectance" is a measure of the proportion of light or other radiation that strikes a surface under normal incidence and is reflected from that surface. Reflectance typically varies with wavelength and is reported as a percentage of incident light reflected from the surface (0 percent - no reflected light, 100 - all light reflected). The terms reflectance and reflectance are used interchangeably in this specification.

[0047] The terms "reflectivity" and "reflectivity" refer to the property of reflecting light or radiation, particularly the reflectance, which is measured independently of the thickness of the material.

[0048] The term "average reflectance" refers to the reflectance averaged over a specified wavelength range.

[0049] In quantitative measurement, the term "absorbance" refers to the base-10 logarithm of the ratio of incident radiant power to radiant power transmitted through a material. This ratio can be explained as the value obtained by dividing the radiant flux received by the material by the radiant flux transmitted through the material. Absorbance (A) can be calculated based on transmittance (T) according to the following equation 1: A = -log 10 T (1) Absorbance can be measured using the method described in ASTM E903-12, "Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres." The absorbance measurement described herein is performed by conducting the transmittance measurement as described above, and then calculating the absorbance using equation (1). Emissivity can be measured using an infrared imaging radiometer using the method described in ASTM E1933-14 (2018), "Standard Practice for Measuring and Compensating for Emissibity Using Infrared Imaging Radiometers."

[0050] The term or prefix "micro" refers to at least one dimension that defines a structure or shape as being in the range of 1 micrometer to 1 millimeter. For example, a microstructure may have a height or width in the range of 1 micrometer to 1 millimeter.

[0051] The term or prefix "nano" refers to at least one dimension that defines a structure or shape as being less than 1 micrometer. For example, a nanostructure may have at least one of a height or width less than 1 micrometer.

[0052] The term "proximity" in relation to a particular layer means that two layers are adjacent to each other (i.e., adjacent) and in direct contact, joined to or attached to another layer, or continuous with each other but not in direct contact (i.e., one or more additional layers interposed between them).

[0053] The relative position of an element to a horizontally positioned, upward-facing substrate is referred to by using orientation terms such as "atop," "on," "over," "covering," "uppermost," and "underlying" to describe the location of various elements in the disclosed coated article.

[0054] However, unless otherwise indicated, it is not intended that the substrate or article should have any particular orientation in space during or after manufacturing.

[0055] By using the term “overcoated” to describe the location of a layer on a substrate or other element of the article of this disclosure, it is noted that the layer is present on the substrate or other element, but is not necessarily continuous with either of those elements.

[0056] To describe the position of a layer relative to other layers, the term "separated by" is used, indicating that the layer is located between two other layers, but is not necessarily continuous with or adjacent to either layer.

[0057] The terms “approximately” or “about” relating to numerical values ​​or shapes mean + / - 5 percent of that value or characteristic or feature, but also explicitly include the exact value. For example, a viscosity of “approximately” 1 Pa-sec refers to a viscosity of 0.95 to 1.05 Pa-sec, but also explicitly includes a viscosity of exactly 1 Pa-sec. Similarly, a “approximately square” perimeter is intended to describe a geometric shape having four side edges, each side being 99% to 101% of the length of any other side edge, but also includes a geometric shape where each side edge is exactly the same length.

[0058] The term "substantially" in relation to properties or characteristics means that the property or characteristic is exhibited to a greater extent than the opposite property or characteristic is exhibited. For example, a "substantially" transparent substrate is one that transmits more radiation (e.g., visible light) than radiation that it cannot transmit (e.g., absorbs and reflects). Therefore, a substrate that transmits more than 50% of the visible light incident on its surface is substantially transparent, while a substrate that transmits 50% or less of the visible light incident on its surface is not substantially transparent.

[0059] As used herein and in the accompanying embodiments, the singular forms “a,” “an,” and “the” include multiple references unless the context explicitly states otherwise. Therefore, for example, a reference to a microfiber containing “a compound” includes a mixture of two or more compounds. As used herein and in the accompanying embodiments, the term “or” is used in its general sense to include “and / or” unless the context explicitly states otherwise.

[0060] When used herein, a numerical range description with endpoints includes all numbers contained within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

[0061] Unless otherwise indicated, all numbers used herein and in the embodiments, representing quantities or components, measured values ​​of properties, etc., should be understood in all cases as being modified by the term “about.” Therefore, unless otherwise indicated, the numerical parameters described in the foregoing specification and the appended list of embodiments may vary depending on the desired properties that a person skilled in the art would seek to obtain using the teachings of this disclosure. At a minimum, each numerical parameter should be interpreted by applying ordinary rounding, taking into account the reported number of significant figures, but this is not intended to limit the application of the doctrine of equivalents to the scope of the claimed embodiments.

[0062] By definition, the total weight percentage of all components in a composition is equal to 100 weight percent.

[0063] Next, various exemplary embodiments of the Disclosure will be described. These exemplary embodiments can be modified and altered in various ways without departing from the spirit and scope of the Disclosure. Therefore, it should be understood that the embodiments of the Disclosure are not limited to the exemplary embodiments described below, but are subject to the limitations set forth in the claims and any equivalents thereof.

[0064] UV-C emitting disinfection device Referring here to the drawings, Figure 9 shows a schematic side view of a device, more specifically, a UV-C disinfection device 900 according to an exemplary embodiment of the present disclosure. The device 900 comprises a housing 902 that is substantially impermeable to ultraviolet radiation having wavelengths of 280 nm to 400 nm, at least one window 908 defined within the housing, and an ultraviolet radiation source 904 positioned within the housing. The ultraviolet radiation source 904 is capable of emitting ultraviolet radiation 910 of one or more wavelengths between 100 nm and 400 nm.

[0065] The window 908 includes a UV-C radiation bandpass mirror film comprising a number of alternatingly arranged first and second optical layers that collectively transmit UV-C radiation 914 with wavelengths ranging from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm. The UV-C radiation bandpass mirror film substantially does not transmit UV-A radiation and UV-B radiation with wavelengths between 280 nm and 400 nm. The UV-C radiation emitted from the device can be directed to a material 916 to be disinfected to a desired level of disinfection.

[0066] In some particularly advantageous embodiments, the device 900 further includes an ultraviolet mirror film 906 positioned inside the housing 902 to reflect ultraviolet radiation 910 emitted by an ultraviolet radiation source 904 (912). The ultraviolet mirror film 906 (see Figure 1) includes a number of alternatingly arranged first and second optical layers that collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of incident UV-C ultraviolet radiation in the wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet radiation in the wavelength range from above 230 nanometers, above 235 nm, or above 240 nm to 400 nanometers. At least 50, 60, 70, 80, 90, or 95 percent of ultraviolet radiation with wavelengths of at least 230 nanometers to 400 nanometers that is transmitted through the ultraviolet mirror is absorbed by the ultraviolet mirror film.

[0067] Figure 10 is a schematic perspective view of another UV-C disinfection device 1000 according to an exemplary embodiment of the present disclosure. The device 1000 comprises a housing 1002 that is substantially impermeable to ultraviolet radiation having wavelengths of 280 nm to 400 nm, at least one window 1008 defined within the housing, and an ultraviolet radiation source 1004 positioned within the housing. The ultraviolet radiation source 1004 is capable of emitting ultraviolet radiation 1010 with one or more wavelengths between 100 nm and 400 nm.

[0068] The window 1008 includes a UV-C radiation bandpass mirror film comprising a number of alternatingly arranged first and second optical layers that collectively transmit UV-C radiation 1014 with wavelengths ranging from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm. The UV-C radiation bandpass mirror film substantially does not transmit UV-A radiation and UV-B radiation with wavelengths between 280 nm and 400 nm. The UV-C radiation 1014 emitted from this device can be directed to a material (not shown) to be disinfected to a desired level of disinfection.

[0069] In some particularly advantageous embodiments, the device 1000 further includes an ultraviolet mirror film 1006 positioned inside the housing 1002 to reflect ultraviolet radiation 1010 emitted by an ultraviolet radiation source 1004. The ultraviolet mirror film 1006 (see Figure 1) includes a number of alternatingly arranged first and second optical layers that collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of incident UV-C ultraviolet radiation in the wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet radiation in the wavelength range from above 230 nanometers, above 235 nm, or above 240 nm to 400 nanometers. At least 50, 60, 70, 80, 90, or 95 percent of ultraviolet radiation with wavelengths of at least 230 nanometers to 400 nanometers that is transmitted through the ultraviolet mirror is absorbed by the ultraviolet mirror film.

[0070] In the particular embodiment shown in Figure 10, the window 1006 includes an optional collimator for better aligning the direction of motion of the emitted UV-C radiation 1014 in a specific direction (i.e., for generating collimated light with parallel rays). Suitable collimators are known to those skilled in the art and include, for example, those described in U.S. Patent Applications Publication Nos. 2015 / 0114912(A1) and 2018 / 0201521(A1).

[0071] Figure 11 is a schematic side view of a further UV-C disinfection device 1100 using a collimated broadband UV light source, according to another exemplary embodiment of the present disclosure. The device 1100 comprises a housing 1102 that is substantially impermeable to ultraviolet radiation having wavelengths of 280 nm to 400 nm, at least one window 1108 defined within the housing, and an ultraviolet radiation source 1104 positioned within the housing. The ultraviolet radiation source 1104 is capable of emitting ultraviolet radiation 1110 of one or more wavelengths between 100 nm and 400 nm.

[0072] The window 1108 includes a UV-C radiation bandpass mirror film comprising a number of alternatingly arranged first and second optical layers that collectively transmit UV-C radiation 1114 with wavelengths ranging from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm. The UV-C radiation bandpass mirror film substantially does not transmit UV-A radiation and UV-B radiation with wavelengths between 280 nm and 400 nm. The UV-C radiation 1114 emitted from this device can be directed to a material (not shown) to be disinfected to a desired level of disinfection.

[0073] In some particularly advantageous embodiments, the device 1100 further includes an ultraviolet mirror film 1106 positioned inside the housing 1102 to reflect ultraviolet radiation 1110 emitted by an ultraviolet radiation source 1104. The ultraviolet mirror film 1106 (see Figure 1) includes a number of alternatingly arranged first and second optical layers that collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of incident UV-C ultraviolet radiation in the wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet radiation in the wavelength range from above 230 nanometers, above 235 nm, or above 240 nm to 400 nanometers. At least 50, 60, 70, 80, 90, or 95 percent of ultraviolet radiation with wavelengths of at least 230 nanometers to 400 nanometers that is transmitted through the ultraviolet mirror is absorbed by the ultraviolet mirror film.

[0074] In the particular embodiment shown in Figure 11, the housing 1102 is formed in the shape of a parabolic collimator to better align the direction of motion of the emitted UV-C radiation 1014 in a specific direction (i.e., to produce collimated light having parallel rays). Suitable parabolic collimators are known to those skilled in the art and include, for example, those described in U.S. Patent No. 8,921,813(B2).

[0075] An optical collimator can be designed to collimate light from a point source, which can be collimated (focused) using a parabolic (elliptic) reflective optical element. The main requirements are that the light source is located near the focal point of the optical element and that the light source is relatively small compared to the size of the optical element. The condenser can be designed using a plane of revolution generated from a section of an ellipse, where the light source is at one focal point and the target is at the other. The light source at one focal point emits light toward the nearest vertex of the ellipse. The section of the ellipse used to generate the plane of revolution is defined by the diameter of the light source and the vertex nearest the light source. The diameter must be larger than the light source so that the condenser can collect most of the light from the light source. If the light source and target are points, all the light from the light source will be focused toward the target.

[0076] Light from a point source can be collimated (focused) using a parabolic (elliptical) reflecting optical element, and one suitable collimator for this system is a parabolic collimator. The main requirements are that the light source is located near the focal point of the optical element and that the light source is relatively small compared to the size of the optical element. In most applications, the optical element must be designed with practical considerations in mind, such as the size of the light source and the allowable space for the optical element. Given the diameter Ds (width at 1D) of the light source and the design volume consisting of height Hv and diameter Dv (width at 1D), the following equation can be derived for the approximately optimal shape of the parabolic reflector: y=a * (x+b) 2 +Offset In the formula, a=Hv / ((Dv / 2) 2 -(Ds / 2) 2 ), b = -Dv / 2, and offset = -a * (Ds / 2) 2 And, To ensure that the focus of the parabola coincides with the location of the light source at [x=Dv / 2, y=0], further selection of Hv and / or Dv is necessary, which is achieved by selecting the following: Hv = ((Dv / 2) 2 -(Ds / 2) 2 ) / Ds

[0077] The resulting optical element is almost optimal considering the physical constraints of the system. According to the principle of étendue conservation, the amount of collimation is proportional to (Dv / Ds) 2 and the larger the design volume, the greater the collimation. The cut-off angle of this optical element is given by the following formula: Θ = + / - arctan((Dv / 2 + Ds / 2) / Hv)

[0078] Method of using a UV-C disinfection device FIG. 12 is a flowchart showing an exemplary method 1200 of using a UV-C disinfection device to disinfect a material. Method 1200 includes supplying a disinfection device as described in any of the embodiments disclosed herein (1202), directing ultraviolet radiation emitted by an ultraviolet radiation source through a UV-C bandpass mirror film (1204), and exposing at least one material to the ultraviolet radiation passing through the UV-C bandpass mirror film for a time sufficient to reach the desired degree of disinfection of the at least one material (1206).

[0079] The ultraviolet radiation passing through the UV-C bandpass mirror film has a wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, or 190 nm to less than 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and substantially does not contain UV-A radiation and UV-B radiation with wavelengths of 280 nm to 400 nm. Preferably, the ultraviolet radiation passing through the UV-C bandpass mirror film has a wavelength range of 190 nm to 230 nm as shown in FIG. 12.

[0080] In some exemplary embodiments, the disinfection device can be used in a room where humans will be present. In certain exemplary embodiments, exposure of at least one material to ultraviolet radiation passing through a UV-C bandpass mirror film is performed until a log2, log3, log4, or greater reduction is achieved in the amount of at least one microorganism present on or within the at least one material compared to the amount of at least one microorganism present before the at least one material was exposed to ultraviolet radiation passing through the UV-C bandpass mirror film.

[0081] As used herein, the term “microorganism” refers to any cell or particle (including, for example, bacteria, yeasts, viruses, and bacterial endospores) that has genetic material suitable for analysis or detection. The log reduction value (LRV) can be determined by measuring the number of microbial colonies present on or within a material before disinfection via the exemplary method, disinfecting the material using that method, measuring the number of colonies present on or within the material after disinfection, and then calculating the LRV based on the resulting colony count. The method for measuring the number of colony-forming units (CFUs) on or within a material will vary depending on the morphology of the specific material.

[0082] For example, solids can be collected by swabbing, and liquids or gases can be collected using volumetric methods (and concentrated as needed). CFU can be measured using, for example, culture-based methods, imaging detection methods, fluorescence-based detection methods, colorimetric detection methods, immunological detection methods, gene detection methods, or bioluminescence-based detection methods. The LRV is then calculated using the following formula: LRV = (logarithm of (cfu / area or volume of material before disinfection)) - (logarithm of (cfu / area or volume of material after disinfection))

[0083] Generally, at least one material comprises at least one of a solid, liquid, or gas. When a device is used in this method, at least one material is typically located inside the device housing when exposed to UV-C radiation. As described above, it is sometimes preferable to expose the material to ultraviolet radiation having wavelengths from 190 nm or higher, 195 nm, or 200 nm to 230 nm, 235 nm, or 240 nm.

[0084] In certain currently preferred embodiments, during the process, one or more materials are exposed to 10, 8, 6, 5, 4, 3, 2, or 1 percent or less of ultraviolet radiation having wavelengths from 230 nanometers, 235 nm, or above 240 nm to 400 nanometers, emitted by a broadband UV-C source. This is achieved by the effective absorption of those wavelengths by the absorption layer and / or housing, thereby 90 percent or more of the ultraviolet radiation having wavelengths from 230 nanometers, 235 nm, or above 240 nm to 400 nanometers is absorbed during the process, instead of being directed to and / or reflected towards the material.

[0085] Components of a UV-C emission disinfection device housing The materials constituting the housing 902 are not particularly limited and may include, for example, metal, plastic, ceramic (including glass), concrete, or wood. In certain embodiments, the housing 902 is formed of a heat-resistant or heat-conducting material capable of withstanding the heat generated by the absorption of light of a specific wavelength from a broadband UV-C radiation source located inside the housing 902.

[0086] Preferably, any (co)polymer material used within the housing 902 that is directly exposed to light emission from the broadband UV-C radiation source 904 is positioned at a distance of at least 3 centimeters (cm), 3.25 cm, 3.5 cm, 3.75 cm, or at least 4 cm from the broadband UV-C radiation source 904 to minimize damage from exposure to light of wavelengths not reflected by the optional ultraviolet mirror 906.

[0087] Typically, in the disinfection device according to this disclosure, a broadband UV-C radiation source 904 is configured to direct light to an optional ultraviolet mirror film 906. This allows the ultraviolet mirror film 906 to reflect back light within a desired range of wavelengths (e.g., 190 nm to 240 nm) while transmitting and / or absorbing light with wavelengths exceeding the maximum value of that range (e.g., above 240 nm) to a UV-impermeable housing 902.

[0088] Broadband UV-C radiation source Suitable broadband UV-C radiation sources for use include low-pressure mercury lamps, medium-pressure mercury lamps, xenon arc lamps, or excimer lamps. Suitable low-pressure mercury lamps include those commercially available from Heraeus-Noblelight (Hanau, Germany), and include low-pressure mercury amalgam lamps.

[0089] For example, a low-pressure mercury lamp can provide peak emission at approximately 254 nm and minimum emission at wavelengths below approximately 245 nm and above approximately 260 nm. A suitable medium-pressure mercury lamp is one commercially available from Helios Quartz Americas (Sylvania, OH). By using a 214-type quartz sleeve or synthetic quartz sleeve with a medium-pressure mercury lamp, the amount of emission at 200 nm can be increased by 51% or 89%, respectively.

[0090] The peak emission of a medium-pressure mercury lamp is approximately 320 nm, but medium-pressure mercury lamps are pleochroic and also have several prominent emission peaks from approximately 245 nm to approximately 300 nm, for example at approximately 265 nm, as well as a broad emission band from approximately 210 nm to approximately 240 nm.

[0091] Suitable xenon arc lamps are commercially available from Atlas Material Testing Technology, Inc. (Chicago, IL), Newport (Irvine, CA), and Xenex (San Antonio, TX). Xenon arc lamps tend to have a broad emission spectrum that starts at approximately 200 nm to 250 nm, with several small peaks at approximately 475 nm and 775 nm, extending beyond 800 nm.

[0092] Examples of excimer ultraviolet radiation sources include lamps commercially available from Osram (Massachusetts, United States), Heraeus-Noblelight (Hanau, Germany), Ushio (Tokyo, Japan), and those described in Kogelschatz, Applied Surface Science, 54 (1992), 410-423; glow discharge lamps described in European Patent Application Nos. 521 and 553 (granted to NVPhilips); deuterium lamps available from Hamamatsu (Hamamatsu City, Japan); and those described by Kitamura et al., Applied Surface Science, 79 / 80 (1994), 507-513, and (Fusion). Examples include microwave-driven lamps, such as those described in German Published Patent No. 4302555(A1) granted to Systems, and excimer lamps excited by volume discharge with ultraviolet pre-ionization, such as those described in Tech.Phys, 39(10), 1054 (1994). Excimer ultraviolet radiation sources often contain krypton bromide or krypton chloride. For example, deuterium lamps typically have an emission spectrum exhibiting a broad peak bandwidth of about 200 nm to about 280 nm, followed by a gradual decrease in the bandwidth of about 280 nm to about 700 nm.

[0093] The ultraviolet mirror and absorption layer are according to any embodiment of these parts of the multilayer article of the first embodiment described in detail above. The broadband UV-C radiation source is according to any embodiment of the broadband UV-C radiation source of the second embodiment described in detail above.

[0094] UV-C mirror film The disinfection device according to this disclosure may include, as a component, one or more UV-C mirror films that can function as either a UV-C bandpass filter mirror film capable of selectively passing UV-C radiation, or a UV-C (and optionally UV-A and UV-B) reflective protective mirror film.

[0095] Bandpass filter UV-C mirror film In some embodiments of the multilayer optical films described herein, at least a first optical layer comprises an inorganic material (e.g., at least one of zirconium oxynitride, hafnia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride), and a second optical layer comprises an inorganic material (e.g., at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica-alumina oxide, or alumina-doped silica). Exemplary materials are available, for example, from Materion Corporation (Mayfield Heights, OH) and Umicore Corporation (Brussels, Belgium).

[0096] In any of the embodiments described above, the transmittance of incident visible light passing through at least a plurality of alternately arranged first and second optical layers is greater than 30 percent over a wavelength reflection bandwidth of at least 30 nanometers in the wavelength range of at least 400 nanometers to 750 nanometers.

[0097] In any of the embodiments described above, at least the first optical layer comprises at least one of titania, zirconia, zirconium, nitrogen oxide, hafnia, or alumina, and the second optical layer comprises at least one of silica, aluminum fluoride, or magnesium fluoride.

[0098] UV radiation reflective mirror film The disclosure also describes a multilayer ultraviolet radiation reflective mirror film which can be used inside a UV-irresistible housing of a disinfection device to reflect UV radiation from a broadband UV light source to a window in the disinfection device, which is covered with a multilayer UV-C mirror film that acts as a bandpass filter to allow the emission of a substantial amount of UV-C radiation useful for disinfecting surfaces.

[0099] In some particularly advantageous embodiments, the device further includes an ultraviolet mirror film positioned inside the housing to reflect ultraviolet radiation emitted by an ultraviolet radiation source. The ultraviolet mirror film includes a number of alternatingly arranged first and second optical layers that collectively reflect at least 50, 60, 70, 80, 90, or 95 percent of incident UV-C ultraviolet radiation in the wavelength range from at least 100 nm, 125 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm to 400 nm, 300 nm, 280 nm, 270 nm, 260 nm, 250 nm, 240 nm, or 230 nm, and collectively transmit at least 50, 60, 70, 80, 90, or 95 percent of incident ultraviolet radiation in the wavelength range from above 230 nanometers, above 235 nm, or above 240 nm to 400 nanometers. At least 50, 60, 70, 80, 90, or 95 percent of ultraviolet radiation with wavelengths of at least 230 nanometers to 400 nanometers that is transmitted through the ultraviolet mirror is absorbed by the ultraviolet mirror film.

[0100] UV-C (and optionally UV-A and UV-B) reflective protective film Furthermore, since some surfaces disinfected with ultraviolet radiation (e.g., (co)polymer surfaces) may need to be protected even from UV-C ultraviolet light, this disclosure also relates to UV-C mirror protective films that can protect the underlying surface to which the UV mirror protective film is applied from damage caused by UV irradiation exposure by reflecting UV-C radiation and optionally one or more of UV-A and UV-B radiation.

[0101] Therefore, in another embodiment, the present disclosure describes a UV-C mirror film comprising a substrate made of a fluoropolymer, a multilayer optical film disposed on the main surface of the substrate, comprising at least a plurality of alternatingly arranged first and second optical layers that collectively reflect at least 30 percent of incident ultraviolet radiation over a wavelength reflection bandwidth of at least 30 nanometers in the wavelength range of at least 100 nanometers to 280 nanometers, or optionally in the wavelength range of at least 240 nm to 400 nm, at at least one incident light angle of 0°, 30°, 45°, 60°, or 75°, in the wavelength range of at least 30 nanometers, and a heat-sealable adhesive layer disposed on the main surface of the multilayer optical film opposite to the substrate.

[0102] In one exemplary embodiment, the Disclosure describes a UV-C reflective mirror film comprising a substrate made of a fluoropolymer; a multilayer optical film disposed on the main surface of the substrate, comprising at least a plurality of alternating first and second optical layers that collectively reflect at least 30 percent of incident ultraviolet radiation over a wavelength reflection bandwidth of at least 30 nanometers in the wavelength range of at least 100 nanometers to 280 nanometers at at least one incident light angle of 0°, 30°, 45°, 60°, or 75°, over a wavelength reflection bandwidth of at least 30 nanometers; and a heat-sealable adhesive layer disposed on the main surface of the multilayer optical film opposite to the substrate.

[0103] Referring here to Figure 1, an exemplary UV-C mirror film 10 comprises a fluoropolymer substrate 11, a multilayer optical film 20 (e.g., a UV-C mirror film) disposed on the main surface of the substrate, and an optional adhesive layer 14 disposed on the main surface of the multilayer optical film 20, opposite to the substrate 11. The multilayer optical film 20 consists of first optical layers 12A, 12B, 12N and second optical layers 13A, 13B, 13N. In some exemplary embodiments, an optional protective film 15, preferably composed of a fluoropolymer (co)polymer, is disposed on the main surface of the heat-sealable adhesive layer 14, opposite to the multilayer optical film 20.

[0104] When used as a bandpass filter, the UV-C mirror film is preferably a multilayer dielectric mirror comprising at least nine alternating layers of inorganic HIO and inorganic LIO, or at least 100 layers of fluoropolymer (PVDF or ETFE) HIO and fluoropolymer (THV or FEP) LIO. The UV-C transparent fluoropolymer substrate 11 can be positioned either above the multilayer optical film 20 or below the multilayer optical film 20 (not shown), as shown in Figure 1. If the UV-C transparent fluoropolymer substrate 11 is positioned below the multilayer optical film 20, an optional adhesive layer can be positioned adjacent to the multilayer optical film 20 on the opposite side of the fluoropolymer substrate 11, or adjacent to the fluoropolymer substrate on the opposite side of the multilayer optical film 20.

[0105] In some such embodiments, an optional adhesive layer can protect an adhesive, such as a polyolefin copolymer, which has lower UV-C stability but is lighter and less expensive, by coating it onto a fluoropolymer (co)polymer having a melting point above 150°C, or by co-extruding it with such a fluoropolymer (co)polymer. Silicone adhesives are also conceived as useful embodiments of the present invention.

[0106] Fluoropolymer base material In any of the embodiments described above, the fluoropolymer substrate is composed of a (co)polymer comprising tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, perfluoroalkoxyalkane, or a combination thereof. Suitable fluoropolymer substrates are available from Nowofol Kunststoffprodukte GmbH KG (Siegsdorf, Germany) under the trade name "NOWOFLON," of which NOWOFLON THV815 is currently preferred.

[0107] Multilayer optical film Generally, the multilayer optical films described herein include at least three layers (typically ranging from 3 to 2000 or more in total). The multilayer optical films described herein include at least a plurality of alternating first and second optical layers that collectively reflect at least 30 percent (in some embodiments, at least 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or at least 90 percent) of incident ultraviolet (UV) light (i.e., any light having wavelengths in the range from 100 to less than 400 nm) over a wavelength reflection bandwidth of at least 30 nanometers in the wavelength range of at least 100 to 280 (in some embodiments, at least 180 to 280, or even further at least 200 to 280) nm at at least one incident light angle of 0°, 30°, 45°, 60°, or 75°. In some embodiments, the multilayer optical film has a UV reflectivity of more than 90% (more than 99% in some embodiments) at at least one of 222 nm, 254 nm, 265 nm, or 275 nm.

[0108] In some embodiments, the multilayer optical films described herein have a UV transmission band edge with transmittance in the range of 10 to 90 percent over less than 20 nanometers (in some embodiments, less than 15 nanometers, or even less than 10 nanometers).

[0109] optical layer In any of the embodiments described above, at least the first optical layer comprises at least one polyethylene(co)polymer, and the second optical layer comprises at least one fluoropolymer selected from tetrafluoroethylene(co)polymer, hexafluoropropylene(co)polymer, vinylidene fluoride(co)polymer, hexafluoropropylene(co)polymer, perfluoroalkoxyalkane(co)polymer, or a combination thereof. In some such embodiments, at least one fluoropolymer is crosslinked.

[0110] In some embodiments of the multilayer optical films described herein, at least a first optical layer 12A comprises a polymer material (e.g., at least one of polyvinylidene fluoride (PVDF) and ethylene tetrafluoroethylene (ETFE)), and a second optical layer 13A comprises a polymer material (e.g., a copolymer (THV), or at least one of a polyethylene copolymer containing subunits derived from tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF), a copolymer (FEP) containing subunits derived from tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), or a perfluoroalkoxyalkane (PFA)).

[0111] Exemplary materials for creating optical layers that reflect blue light (e.g., a first optical layer and a second optical layer) include polymers (e.g., polyesters, (co)polyesters, and modified (co)polyesters). In the context of this specification, the term “polymer” is understood to include homopolymers and copolymers, as well as polymers or copolymers that can be formed in miscible blends, for example by co-extrusion or by reactions including transesterification. The terms “polymer” and “copolymer” include both random copolymers and block copolymers.

[0112] Polyesters suitable for use in some exemplary multilayer optical films constructed in accordance with this disclosure generally comprise dicarboxylic acid ester and glycol subunits and can be produced by the reaction of carboxylic acid monomer molecules with glycol monomer molecules. Each dicarboxylic acid ester monomer molecule has two or more carboxylic acid groups or ester functional groups, and each glycol monomer molecule has at least two hydroxyl functional groups. The dicarboxylic acid ester monomer molecules may all be the same, or there may be two or more different types of molecules. The same is true for glycol monomer molecules. The term “polyester” also includes polycarbonates derived from the reaction of glycol monomer molecules with carbonate esters.

[0113] Suitable examples of dicarboxylic acid monomer molecules for use in forming carboxylic acid subunits in polyester layers include 2,6-naphthalenedicarboxylic acid and its isomers, terephthalic acid, isophthalic acid, phthalic acid, azelaic acid, adipic acid, sebacic acid, norbornenedicarboxylic acid, bicyclooctanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and its isomers, t-butylisophthalic acid, trimellitic acid, sodium sulfonated isophthalate, 4,4'-biphenyldicarboxylic acid and its isomers, and lower alkyl esters of these acids, such as methyl esters or ethyl esters. In the context of this specification, the term "lower alkyl" refers to C1-C 10 This refers to a linear or branched alkyl group.

[0114] Suitable glycol monomer molecules for use in forming glycol subunits of polyester layers include ethylene glycol, propylene glycol, 1,4-butanediol and its isomers, 1,6-hexanediol, neopentyl glycol, polyethylene glycol, diethylene glycol, tricyclodecanediol, 1,4-cyclohexanedimethanol and its isomers, norbornenediol, bicyclooctanediol, trimethylolpropane, pentaerythritol, 1,4-benzenedimethanol and its isomers, bisphenol A, 1,8-dihydroxybiphenyl and its isomers, and 1,3-bis(2-hydroxyethoxy)benzene.

[0115] Another exemplary birefringent polymer useful for reflective layers is polyethylene terephthalate (PET), which can be produced, for example, by the reaction of terephthalic acid dicarboxylic acid with ethylene glycol. The refractive index of the birefringent polymer for incident polarized light at a wavelength of 550 nm increases from about 1.57 to about 1.69 when the plane of polarization is parallel to the stretching direction. As molecular orientation increases, the birefringence of PET increases. Molecular orientation can be increased by stretching the material to a larger stretch ratio and by fixing and maintaining other stretching conditions. Copolymers of PET (CoPET), such as those described in U.S. Patent No. 6,744,561 (Condo et al.) and No. 6,449,093 (Hebrink et al.), whose disclosures are incorporated herein by reference, are particularly useful because their relatively low-temperature (typically below 250°C) processing ability enhances their compatibility for co-extrusion with a second polymer with lower thermal stability. Other semicrystalline polyesters suitable as birefringent polymers include polybutylene terephthalate (PBT) and its copolymers, such as those described in U.S. Patent No. 6,449,093 (Hebrink et al.) and U.S. Patent Application Publication No. 2006 / 0084780 (Hebrink et al.), whose disclosures are incorporated herein by reference. Another useful birefringent polymer is syndiotactic polystyrene (sPS).

[0116] The first optical layer may also be an isotropic high refractive index layer comprising at least one of the following: poly(methyl methacrylate), polypropylene copolymer, polyethylene copolymer, cyclic olefin copolymer, cyclic olefin block copolymer, polyurethane, polystyrene, isotactic polystyrene, atactic polystyrene, polystyrene copolymer (e.g., copolymer of styrene and acrylate), polycarbonate, polycarbonate copolymer, miscible blend of polycarbonate and (co)polyester, or miscible blend of poly(methyl methacrylate) or poly(vinylidene fluoride).

[0117] The second optical layer may also include fluorinated copolymer materials, such as fluorinated ethylene propylene copolymer (FEP), copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride (THV), and at least one copolymer of tetrafluoroethylene, hexafluoropropylene, or ethylene. Particularly useful are melt-processable copolymers of tetrafluoroethylene with at least two or at least three additional different comonomers.

[0118] Exemplary melt-processable copolymers of the aforementioned tetrafluoroethylene and other monomers are available from Dyneon LLC (Oakdale, MN) under the trade names "DYNEON THV 221", "DYNEON THV 230", "DYNEON THV 2030", "DYNEON THV 340GZ", "DYNEON THV 500", "DYNEON THV 610", and "DYNEON THV 815"; from Daikin Industries, Ltd. (Osaka, Japan) under the trade name "NEOFLON EFEP"; and from Asahi Glass Co., Ltd. (Tokyo, Japan) under the trade name "AFLAS", as copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride; as well as from Dyneon LLC (Oakdale, MN) under the trade names "DYNEON ET 6210A" and "DYNEON ET 6235"; and from EIduPont de Examples include copolymers of ethylene and tetrafluoroethylene, available from Nemours and Co. (Wilmington, DE) under the trade name "TEFZEL ETFE" and from Asahi Glass Co., Ltd. (Tokyo, Japan) under the trade name "FLUON ETFE".

[0119] Furthermore, the second polymer can be formed from homopolymers and copolymers of polyester, polycarbonate, fluoropolymer, polyacrylate, and polydimethylsiloxane, as well as blends thereof.

[0120] Other exemplary polymers for use in optical layers, particularly the second layer, include, for example, homopolymers of polymethyl methacrylate (PMMA), such as those available from Ineos Acrylics, Inc. (Wilmington, DE) under trade names "CP71" and "CP80," and homopolymers of polyethyl methacrylate (PEMA) having a lower glass transition temperature than PMMA. Further useful polymers include PMMA copolymers (CoPMMA), such as CoPMMA made from 75% by weight of methyl methacrylate (MMA) monomer and 25% by weight of ethyl acrylate (EA) monomer (e.g., available from Ineos Acrylics, Inc. (London, England) under the trade name "PERSPEX CP63" or from Arkema Corp. (Philadelphia, PA) under the trade name "ATOGLAS 510"), CoPMMA formed from MMA comonomer units and n-butyl methacrylate (nBMA) comonomer units, or blends of PMMA with poly(vinylidene fluoride) (PVDF).

[0121] Further polymers suitable for the optical layer include, for example, polyolefin copolymers such as poly(ethylene-co-octene) (PE-PO), available from Dow Elastomers, Inc. (Midland, MI) under the trade name "ENGAGE 8200", polyethylene methyl acrylate, also available from Dow Elastomers, Inc. (Midland, MI) under the trade name "ELVALOY 1125", poly(propylene-co-ethylene) (PPPE), available from Atofina Petrochemicals, Inc. (Houston, TX) under the trade name "Z9470", and copolymers of atactic polypropylene (aPP) and isotactic polypropylene (iPP). The multilayer optical film may also include a functionalized polyolefin in the second layer (for example, linear low-density polyethylene-grafted maleic anhydride (LLDPE-g-MA), which is available, for example, from EIduPont de Nemours & Co., Inc. (Wilmington, DE) under the trade name "BYNEL 4105").

[0122] The choice of polymer combinations used in creating multilayer optical films depends, for example, on the desired bandwidth of reflection. A larger difference in refractive index between the polymer of the first optical layer and the polymer of the second optical layer creates greater optical power and therefore allows for a wider reflection bandwidth. Alternatively, additional layers can be used to provide greater optical power. Exemplary combinations of birefringent layers and second polymer layers include, for example: PET / THV, PET / SPOX, PET / CoPMMA, CoPEN / PMMA, CoPEN / SPOX, sPS / SPOX, sPS / THV, CoPEN / THV, a blend of PET / PVDF and PMMA, PET / fluoropolymer, sPS / fluoroelastomer, and CoPEN / fluoropolymer.

[0123] Exemplary material combinations for creating optical layers that reflect UV light (e.g., a first optical layer and a second optical layer) include: poly(methyl methacrylate) (PMMA) (e.g., first optical layer) / THV (e.g., second optical layer), PMMA (e.g., first optical layer) / a blend of PVDF and PMMA (e.g., second optical layer), PC (polycarbonate) (e.g., first optical layer) / PMMA (e.g., second optical layer), PC (polycarbonate) Examples include a PET (e.g., first optical layer) / a blend of PMMA and PVDF (e.g., second optical layer), a copolyethylene (e.g., polyethylene methyl acrylate) (e.g., first optical layer) / THV (e.g., second optical layer), a PMMA / PVDF blend (e.g., first optical layer) / PVDF / PMMA blend (e.g., second optical layer), and a PET (e.g., first optical layer) / CoPMMA (e.g., second optical layer).

[0124] In some embodiments, the first optical layer is a fluoropolymer, and the second optical layer is a fluoropolymer. Examples of preferred materials for such embodiments include ETFE / THV, PMMA / THV, PVDF / FEP, ETFE / FEP, PVDF / PFA, and ETFE / PFA. In one exemplary embodiment, for a multilayer UV-C reflective mirror reflecting 300-400 nm, THV, available from Dyneon LLC (Oakdale, MN) under trade names such as "DYNEON THV 221 GRADE," "DYNEON THV 2030 GRADE," or "DYNEON THV 815 GRADE," is used as the second optical layer together with PMMA as the first optical layer. In another exemplary embodiment, a THV available from Dyneon LLC (Oakdale, MN) under the trade names "DYNEON THV 221 GRADE," "DYNEON THV 2030 GRADE," or "DYNEON THV 815 GRADE" is preferably used as the second optical layer in combination with "ELVALOY 1125" available from Dow Elastomers, Inc. (Midland, MI) as the first optical layer.

[0125] Examples of materials for creating an optical layer that absorbs UV or blue light include COC, EVA, TPU, PC, PMMA, CoPMMA, siloxane polymers, fluoropolymers, THV, PET, PVDF, or a blend of PMMA and PVDF.

[0126] A UV-absorbing layer (e.g., a UV protective layer) helps protect a visible / IR reflective optical layer laminate from UV-induced damage / degradation over time by absorbing UV light (e.g., any UV light) that could pass through the UV reflective optical layer laminate. Generally, a UV-absorbing layer may include any polymer composition (i.e., polymer + additives) including a pressure-sensitive adhesive composition that can withstand UV light over long periods of time.

[0127] LED UV light, particularly ultraviolet radiation in the 280-400 nm range, can induce degradation of plastics, resulting in discoloration and deterioration of optical and mechanical properties. Suppressing photo-oxidative degradation is crucial for outdoor applications where long-term durability is essential. UV light absorption by polyethylene terephthalate begins, for example, at approximately 360 nm, increases significantly below 320 nm, and is extremely pronounced below 300 nm. Polyethylene naphthalate intensely absorbs UV light in the 310-370 nm range, with absorption ending at approximately 410 nm, and absorption maxima occurring at 352 nm and 337 nm. Chain cleavage occurs in the presence of oxygen, and the main photo-oxidation products are carbon monoxide, carbon dioxide, and carboxylic acid. In addition to the direct photodegradation of ester groups, oxidation reactions must be considered, which also form carbon dioxide via peroxide radicals.

[0128] A UV-absorbing layer can protect a multilayer optical film by reflecting, absorbing, scattering, or a combination thereof of UV light. Generally, a UV-absorbing layer may comprise any polymer composition capable of reflecting, scattering, or absorbing UV radiation while simultaneously withstanding UV radiation over extended periods. Examples of such polymers include PMMA, CoPMMA, silicone thermoplastics, fluoropolymers, and their copolymers, as well as blends thereof. An exemplary UV-absorbing layer comprises a PMMA / PVDF blend.

[0129] Selective adhesive layer In any of the embodiments described above, the optional adhesive layer comprises a (co)polymer. In any of the embodiments described above, the (co)polymer is selected from olefin (co)polymers, (meth)acrylate (co)polymers, urethane (co)polymers, fluoropolymers, silicone (co)polymers, or combinations thereof. In certain such embodiments, the (co)polymer is an olefin (co)polymer selected from low-density polyethylene, linear low-density polyethylene, ethylene vinyl acetate, polyethylene methyl acrylate, polyethylene octene, polyethylene propylene, polyethylene butene, polyethylene maleic anhydride, polymethylpentene, polyisobutene, polyisobutylene, polyethylene propylene diene, cyclic olefin copolymers, and blends thereof.

[0130] In some of the embodiments described above, the (co)polymer has a melting temperature of less than 160°C. In certain such embodiments, the (co)polymer is crosslinked. In some such embodiments, the (co)polymer further comprises an ultraviolet radiation absorber, a hindered amine light stabilizer, an antioxidant, or a combination thereof. In further such embodiments, the ultraviolet radiation absorber is selected from benzotriazole compounds, benzophenone compounds, triazine compounds, or a combination thereof.

[0131] One exemplary heat-sealable fluoropolymer adhesive material is available from Dyneon LLC (Oakdale, MN) as THV221GZ. Another exemplary heat-sealable fluoropolymer adhesive material is available from 3M Dyneon LLC (Oakdale, MN) as THV340GZ. Other exemplary heat-sealable adhesives for photovoltaic modules can also be found in the patent applications International Publication No. 2013066459(A1) (Rasal et al.) and International Publication No. 2013066460(A1) (Rasal et al.), the entire disclosure of which is incorporated herein by reference.

[0132] The optional adhesive layer can be crosslinked with a photoinitiator or thermal initiator during or after bonding to the photovoltaic cell. Examples of photoinitiators include benzophone, orthomethoxybenzophone, paraethoxybenzophenone, acetophenone, orthomethoxyacetophenone, hexaphenone, polymethyl vinyl ketone, polyvinylaryl ketone, oligo(2-hydroxy-2-methyl-1-4(1-methylvinyl)propanone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one, such as Escacure KIP150 available from Arkema Sartomer (Exton, PA). The heat-sealable adhesive layer can be cured by radiation-mediated crosslinking, such as using X-ray irradiation, gamma radiation, ultraviolet electromagnetic radiation, and electron beam irradiation.

[0133] Crosslinking can also be facilitated by thermochemical crosslinking agents, including peroxides, amines, silanes, and sulfur-containing compounds. Exemplary organic peroxide crosslinking agents include 2,7-dimethyl-2,7-di(t-butylperoxy)octadiin-3,5 and 2,7-dimethyl-2,7-di(peroxyethyl carbonate)octadiin-3,5. Another exemplary crosslinking agent is dicumyl peroxide, available from Elf Atochem North America (St. Louis, MO) as Luperox 500R.

[0134] Optional additives An exemplary adhesive layer may contain a UV absorber, a hindered amine light stabilizer, and an antioxidant. Benzotriazole, benzophenone, and triazine UV absorbers are available from BASF USA (Florham Park, NJ) under trade names Tinuvin and Chemisorb, such as Tinuvin P, Tinuvin 326, Tinuvin 327, Tinuvin 360, Tinuvin 477, Tinuvin 479, Tinuvin 1577, and Tinuvin 1600. Suitable hindered amine light stabilizers are also available from BASF as Tinuvin 123, Tinuvin 144, and Tinuvin 292.

[0135] Exemplary antioxidants are also available from BASF (Florham Park, NJ) under trade names Irganox, Irgafos, and Irgastab. Exemplary antioxidants for polyolefins include Irganox 1010, Irganox 1076, and Irgafos 168. Further olefin polymer stabilizers are available from Solvay under trade names CYTEC, CYASORB, CYANOX, and CYNERGY, such as CYASORB THT460, CYASORB UV3529, CYNERGY400, and CYANOX2777.

[0136] By incorporating various optional additives into the optical layer, the optical layer can be made UV-absorbing. Examples of such additives include at least one of the following: UV absorbers, hindered amine light stabilizers, or antioxidants.

[0137] Particularly desirable UV absorbers are redshift UV absorbers (RUV-A) that absorb at least 70% (in some embodiments, at least 80%, or even more than 90%) of UV light in the wavelength range of 180 nm to 400 nm. Typically, RUV-A is desirable if it is highly soluble in polymers, highly light-absorbent, light-resistant, and thermally stable in the 200°C to 300°C temperature range for extrusion processes to form a protective layer. RUV-A may also be very suitable if it can be copolymerized with monomers to form a protective coating layer by UV curing, gamma ray curing, electron beam curing, or thermosetting processes.

[0138] RUV-A typically has an enhanced spectral effective range in the long-wave UV region, enabling it to block high-wavelength UV light that can cause yellowing of polyesters. Typical UV protective layers have thicknesses ranging from 13 micrometers to 380 micrometers (0.5 mil to 15 mil) and have an RUV-A filling concentration of 2 to 10 wt%. One of the most effective RUV-A compounds is the benzotriazole compound 5-trifluoromethyl-2-(2-hydroxy-3-α-cumyl-5-tert-octylphenyl)-2H-benzotriazole (available from BASF (Florham Park, NJ) under the trade name "CGL-0139").

[0139] Other exemplary benzotriazoles include 2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole, 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzothiazole, 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole, 2-(2-hydroxy-3-α-cumyl-5-tert-octylphenyl)-2H-benzotriazole, and 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole. A further exemplary RUV-A is 2(-4,6-diphenyl-1-3,5-triazine-2-yl)-5-hexyloxyphenol.

[0140] Other exemplary UV absorbers are available from BASF (Florham Park, NJ) under the trade names "TINUVIN 1577," "TINUVIN 900," "TINUVIN 1600," and "TINUVIN 777." Further exemplary UV absorbers are available, for example, from Sukano Polymers Corporation (Dunkin, SC) under the trade name "TA07-07 MB" as a polyester masterbatch.

[0141] An example of a UV absorber for polymethyl methacrylate is a masterbatch available, for example, from Sukano Polymers Corporation (Dunkin, SC) under the trade name "TA11-10 MBO1".

[0142] An exemplary UV absorber for polycarbonate is the masterbatch "TA28-09 MB01" from Sukano Polymers Corporation. Furthermore, the UV absorber can be used in combination with hindered amine light stabilizers (HALS) and antioxidants. Exemplary HALS are available from BASF under the trade names "CHIMASSORB 944" and "TINUVIN 123". Exemplary antioxidants are also available from BASF (Florham Park, NJ) under the trade names "IRGANOX 1010" and "ULTRANOX 626".

[0143] Other additives can be included in the UV-absorbing layer (e.g., the UV-protective layer). Non-pigmented zinc oxide and titanium dioxide particles can also be used as blocking or scattering additives within the UV-absorbing layer. For example, UV radiation degradation can be minimized by dispersing nanoscale particles in a polymer or coating substrate. Nanoscale particles reduce damage to thermoplastic resins by scattering or absorbing harmful UV radiation while remaining transparent to visible light.

[0144] U.S. Patent No. 5,504,134 (Palmer et al.), whose entire disclosure is incorporated herein by reference, describes the mitigation of ultraviolet radiation-induced polymer substrate degradation by using metal oxide particles in a size range of approximately 0.001 to approximately 0.2 micrometers in diameter (in some embodiments, approximately 0.01 to approximately 0.15 micrometers).

[0145] U.S. Patent No. 5,876,688 (Laundon), whose entire disclosure is incorporated herein by reference, describes a method for producing finely powdered zinc oxide that is small enough to be transparent when incorporated as a UV blocking and / or UV scattering agent in paints, coatings, finishes, plastic articles, cosmetic materials, etc., suitable for use in the present invention. These fine particles, such as zinc oxide and titanium oxide, having particle sizes in the range of 10 nm to 100 nm and capable of attenuating UV radiation, are available, for example, from Kobo Products, Inc. (South Plainfield, NJ). Flame retardants can also be incorporated into the UV protective layer as additives.

[0146] In addition to adding UV absorbers, HALS, nanoscale particles, flame retardants, antibacterial agents, wetting agents, and antioxidants to the UV absorbing layer, UV absorbers, HALS, nanoscale particles, flame retardants, and antioxidants can also be added to the multilayer optical film and any of the optional durable topcoat layers.

[0147] Fluorescent molecules and fluorescent whitening agents can also be added to UV-absorbing layers, multilayer optical layers, optional hard coat layers, or combinations thereof. Blue light-absorbing dyes or pigments are available, for example, from Clariant Specialty Chemicals (Charlotte, NC) under the trade name "PV FAST YELLOW" and can be added to the skin layer or top coat. In exemplary embodiments, antimicrobial agents and wetting agents can be added to the skin layer, which migrate to the surface exposed to air. Wetting agents may be required to prevent fogging due to condensation.

[0148] The desired thickness of a UV protective layer typically depends on a target optical density at a particular wavelength, such as that calculated by Beer's Law. In some embodiments, the UV protective layer has an optical density greater than 3.5, 3.8, or 4 at 380 nm, greater than 1.7 at 390 nm, and greater than 0.5 nm at 400 nm. Those skilled in the art will recognize that, in order to provide the intended protective function, the optical density should typically be maintained substantially constant over the long lifespan of the article.

[0149] An optional UV protective layer and any optional additive can be selected to achieve a desired protective function, such as UV protection. Those skilled in the art will recognize that numerous means exist for achieving the above objectives of a UV protective layer. For example, additives that are highly soluble in a particular polymer can be added to the composition.

[0150] Of particular importance is the durability of the additives within the polymer. The additives should not degrade or migrate outside the polymer. Furthermore, the thickness of the layer can be changed to achieve the desired protective result. For example, a thicker UV protective layer allows the same UV absorbance level with a lower concentration of UV absorber and results in longer UV absorber durability due to the smaller driving force that moves the UV absorber.

[0151] One mechanism for detecting changes in physical properties is to use the weathering test cycle described in ASTM G155-05a (October 2005) and a D65 light source operating in reflective mode. In the above test, if a UV protective layer is applied to the article, the article will be subjected to CIE L before the occurrence of significant cracking, delamination, interlayer delamination, or haze. * a * b * b obtained using space * The value increases to 5 or less, 4 or less, 3 or less, or 2 or less, until at least 18,700 kJ / m³ is reached at 340 nm. 2 You should be able to withstand exposure to it.

[0152] An exemplary UV-C protective layer is a crosslinked fluoropolymer. Fluoropolymers can be crosslinked by electron beam irradiation. A crosslinked fluoropolymer layer may have a crosslink density gradient, with a high crosslink density on its first surface and a lower crosslink density on its second surface. This crosslink density gradient can be achieved with low electron beam voltages in the range of 50kV to 150kV.

[0153] Another exemplary UV-C protective layer is a cross-linked silicone polymer. Cross-linked silicone polymers may also contain nanosilica particles and silsesquioxane particles. An exemplary cross-linked silicone polymer coating containing nanosilica particles is available from Ulta-Tech International, Inc. (Jacksonville, FL) under the trade name "GENTOO".

[0154] The multilayer optical films described herein can be manufactured using common processing techniques, such as those described in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference.

[0155] The exemplary UV-C multilayer optical films and UV-C shielding films described herein are preferably flexible. Flexible UV-C multilayer optical films and UV-C shields can be wrapped around a rod with a diameter of 1 m or less (in some embodiments, 75 cm, 50 cm, 25 cm, 10 cm, 5 cm or less, or even 1 cm or less) without producing visible cracks.

[0156] Method for manufacturing ultraviolet bandpass filters and reflective [protective] mirror films. In further exemplary embodiments, the disclosure describes a method for producing a UV-C mirror film according to one of the earlier embodiments of UV-C mirror films. The method includes supplying a substrate composed of a fluoropolymer, supplying a multilayer optical film to be placed on the main surface of the substrate, and heat-sealing the multilayer optical film to the substrate with a heat-sealable adhesive layer. In some currently preferred embodiments, the multilayer optical film is produced using a multilayer co-extrusion die.

[0157] A preferred method for producing a multilayer optical film having a controlled spectrum is: For example, this may include the use of an axial rod heater to control the thickness value of a co-extruded polymer layer, as described in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference; timely feedback of the thickness profile during manufacturing from a thickness measurement tool such as an atomic force microscope (AFM), transmission electron microscope, or scanning electron microscope; optical modeling to generate a desired thickness profile; and iterative adjustment of the axial rod based on the difference between the measured thickness profile and the desired thickness profile.

[0158] The basic process for controlling layer thickness profiles involves adjusting the zone output settings of the axial rods based on the difference between the target layer thickness profile and the measured layer profile. The increase in axial rod output required to adjust the layer thickness value in a given feedblock zone can first be calibrated in terms of watts of thermal input, according to the resulting nanometer thickness change of the layer generated in that heater zone. For example, fine-tuning of the spectrum is possible using 24 axial rod zones for 275 layers. Once calibrated, given the target and measured profiles, the required output adjustments can be calculated. This procedure is repeated until the two profiles converge.

[0159] The layer thickness profile (layer thickness value) of the multilayer optical film described herein, which reflects at least 50 percent of incident UV light over a specified wavelength range, can be adjusted to be a nearly linear profile, with the first (thinnest) optical layer adjusted to have an optical thickness (refractive index × physical thickness) of about 1 / 4 wavelength for light at 100 nm, and progressing to the thickest layer adjusted to have an optical thickness of about 1 / 4 wavelength for light at 280 nm.

[0160] In this regard, dielectric mirrors with an optical thin-film laminate design, consisting of alternating thin layers of inorganic dielectric material with refractive index contrast, are particularly suitable. For the past several decades, dielectric mirrors have been used for applications in the UV, visible, NIR, and IR spectral regions. Depending on the spectral region being targeted, there are specific materials that are suitable for that region. Furthermore, one of two forms of physical vapor deposition (PVD), namely evaporation or sputtering, is used to coat these materials. Evaporation coating relies on heating the coating material (evaporated substance) to its evaporation temperature. Subsequently, its vapor condenses on the substrate. For evaporation dielectric mirror coating, the electron beam evaporation process is the most commonly used.

[0161] Sputter coating uses high-speed gas ions to collide with the surface of a material ("target"), causing atoms to be ejected, which then condense on a nearby substrate. The rate of the thin-film coating, and the relationship between its structure and properties, are strongly influenced by the coating method used and the settings applied to that method. Ideally, the coating rate should be fast enough to allow for acceptable process throughput and film performance characterized by a high-density, low-stress, void-free, non-optically absorbent coating layer.

[0162] Exemplary embodiments can be designed to have a peak reflectance at 254 nm by both PVD methods. For example, individual substrates are coated by electron beam deposition using HfO2 as the high refractive index material and SiO2 as the low refractive index material. The mirror design has alternating layers of each material with a "quarter-wave optical thickness" (qwot), and these layers are coated one by one until, for example, the reflectance at 254 nm exceeds 99% after 13 layers. The bandwidth of this reflectance peak is approximately 80 nm. The quarter-wave optical thickness is the design wavelength, which in this case is 254 nm divided by 4, i.e., 63.5 nm. The physical thickness of the high refractive index layer (HfO2) is the quotient obtained by dividing qwot by the refractive index of HfO2 at 254 nm (2.41), i.e., 30.00 nm. The physical thickness of the low refractive index layer (MgF2), which has a refractive index of 1.41 at 254 nm, is 45.02 nm. Next, the coating of the thin film laminate, which is composed of alternating layers of HfO2 and SiO2 and designed to have a peak reflectivity at 254 nm, is started by coating layer 1 with HfO2 at a thickness of 30.00 nm.

[0163] In electron beam deposition, a four-hearth deposition source is used. Each hearth is conical in shape and has a volume of 17 cm³. 3 It is filled with HfO2 clumps. A magnetically deflected high-voltage electron beam is raster-scanned across the material surface in a pre-programmed manner, while steadily increasing the beam's filament current.

[0164] Once the pre-programmed process is complete, the HFO2 surface is heated to its evaporation temperature of approximately 2500°C, the supply source shutter opens, and the HfO2 vapor flux is ejected from the supply source in a cosine distribution and condenses on the substrate material above the supply source. To improve coating uniformity, the substrate holder rotates during deposition. When the specified coating thickness (30.00 nm) is reached, the filament current is cut off, the shutter closes, and the HfO2 material is cooled.

[0165] For layer 2, the deposition source is then replaced with a hearth containing a mass of MgF2, and a similar pre-programmed heating process is initiated. In this case, the surface temperature of the MgF2 is approximately 950°C when the supply source shutter is opened, and once the specified coating thickness (45.02 nm) is reached, the filament current is cut off, the shutter is closed, and the HfO2 material is cooled. This stepwise process is continued layer by layer until the total number of design layers is reached. In this optical design, as the total number of layers increases from 3 to 13, the resulting peak reflectivity increases accordingly from 40% at 3 layers to over 99% at 13 layers.

[0166] In another exemplary embodiment, a UV transparent film can be coated using a continuous roll-to-roll (R2R) method with ZrON as the high refractive index material and SiO2 as the low refractive index material. The optical design is the same type of thin film laminate in which qwot layers of the two materials are arranged alternately. For ZrON, which has a refractive index of 2.25 at 254 nm, the target physical thickness was 28.22 nm. For SiO2, which has a refractive index of 1.49 and is sputtered from an aluminum-doped silicon sputtering target, the target thickness was 42.62 nm.

[0167] Layer 1 of ZrON is DC sputtered from a pure zirconium sputtering target in a gas mixture of argon, oxygen, and nitrogen. While argon is the primary sputtering gas, the levels of oxygen and nitrogen are set to achieve transparency, low absorptivity, and high refractive index. The film roll is initially transported at a predetermined speed, and after the output of the sputtering source increases to its maximum operating output, the reactive gas is introduced, and then steady-state conditions are reached. Depending on the length of the film to be coated, this process continues until the entire length is reached. In this case, the sputtering source is perpendicular to the film being coated and wider than the film, resulting in very high uniformity of the coating thickness.

[0168] Once the coated film reaches the desired length, the reactive gas is set to zero and the target is sputtered to a pure Zr surface state. Next, the film direction is reversed and AC frequency (40 kHz) power is applied to the (aluminum-doped) silicon, which forms the replacement pair for the sputtering target, in an argon sputtering atmosphere. Once a steady state is reached, oxygen is introduced as a reactive gas to provide transparency and a low refractive index. At the predetermined process settings and line speed, the second layer is coated over the length coated with respect to layer 1. Again, these sputtering sources are orthogonal to the film being coated and are wider than the film, resulting in very high uniformity of coating thickness. After the coated film reaches the desired length, the reactive oxygen is removed and the target is sputtered to a pure (aluminum-doped) silicon surface state in argon. Depending on the target peak reflectivity, 3 to 5, or 7, or 9, or 11, or 13 layers are coated in this order. Upon completion, the film roll is removed for post-processing.

[0169] For the manufacture of these inorganic coatings, electron beam processes are optimal for coating individual components. While some chambers are designed for R2R film coating, a layer-by-layer coating sequence is still required. For R2R sputtering of films, it is advantageous to use a sputtering system with multiple feed sources arranged around one or possibly two coating drums. In this case, for a 13-layer optical laminate design, a two-pass, or even single-pass, machine-pass process is feasible, sequentially coating alternating high-refractive-index and low-refractive-index layers. The number of machine passes required will depend on the machine design, cost, and the practicality of 13 continuous feed sources. Furthermore, the coating speed must be matched to the single-film line speed.

[0170] The application of this disclosure will be further illustrated with the following detailed examples. These examples are provided to illustrate various specific preferred embodiments and techniques. However, it should be understood that many changes and modifications can be made while remaining within the scope of this disclosure.

[0171] While the numerical ranges and parameters describing the broad scope of this disclosure are approximations, the numerical values ​​described in specific embodiments are reported as accurately as possible. However, each numerical value inherently contains some degree of error, which is inevitable from the standard deviation found in their corresponding test measurements. At the very least, each numerical parameter should be interpreted by applying normal rounding, taking into account the reported number of significant figures, but this is not intended to limit the application of the doctrine of equivalents to the scope of the claimed embodiments.

[0172] Examples These embodiments are provided to further illustrate various specific preferred embodiments and techniques. However, it should be understood that many changes and modifications can be made while remaining within the scope of this disclosure.

[0173] UV-C lifespan test The UV-C lifetime of a specific exemplary UV-C protective mirror film was determined using an aluminum enclosure containing an 118V RRD-30-8S sterilization device manufactured by Atlantic Ultraviolet Corporation (Hauppauge, NY). This device includes eight high-power instantaneous start 254nm UV-C lamps. A constant temperature was maintained by flowing compressed air at a pressure of 124 kPa (18 psi) throughout the length of the lamps to minimize temperature-induced lamp output intensity loss. Test samples were mounted on aluminum slides with appropriately sized windows, and absorbance measurements were performed using a spectrophotometer (available from Shimadzu Instruments (Kyoto, Japan) under the trade name "SHIMADZU 2550 UV-VIS").

[0174] Continuous exposure was performed over discrete time intervals, with the sample removed every 100 hours for absorbance measurement and returned to the exposure housing. Throughout the entire duration of the experiment, the sample was positioned inside the test chamber at a controlled height from the lamp and a controlled distance along the lamp. A UV radiometer (obtained from OPSYTECH Corporation (Makati City, Philippines) under the trade name "UVPAD") was placed inside the chamber alongside the test sample to collect UV (and specifically UV-C) irradiance and dose data every 100 hours throughout the entire exposure process.

[0175] Comparative Example 1 A transparent urethane coating was fabricated using zirconia nanoparticles to absorb UV-C. Upon exposure to UV-C, the coating degraded and yellowed after only 168 hours of exposure to 222 nm UV-C, as shown in Figure 2A. Reference numeral 30 indicates the absorbance spectrum of the unexposed coating after zero hours of UV-C exposure, and reference numeral 31 indicates the absorbance spectrum of the coating after 168 hours of exposure.

[0176] Comparative Example 2 A polyolefin copolymer film, available from USI Group (Taiwan) and sold under the trade name VIVION, was exposed to 254 nm UV-C radiation. As shown in Figure 2B, after only 168 hours of exposure to 254 nm UV-C radiation, a significant loss of light transmittance, expressed as absorbance, was observed, indicating rapid degradation of the film. Reference numeral 32 represents the unexposed film after zero hours of UV-C exposure, while reference numeral 33 represents the film after 168 hours of UV-C exposure.

[0177] Comparative Example 3 A 2 mil (50 micrometer) thick, two-layer fluoropolymer film was formed by co-extruding fluoropolymers (available from Dyneon LLC (Oakdale, MN) under trade names "THV815" and "THV221") onto a film casting wheel cooled to 21°C (70°F) using a 40 mm twin-screw extruder and a flat film extrusion die. This was a 100 micrometer thick fluoropolymer ("THV815") film. This film was heat-sealed to an aluminum sheet at 140°C with the THV221 fluoropolymer side facing the aluminum sheet. The two-layer fluoropolymer film could not be peeled off the aluminum sheet.

[0178] Base film example 1 A 4 mil (100 micrometer) thick THV815 film, obtained from Nowofol Kunststoffprodukte GmbH KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV815," was exposed to 254 nm UV-C radiation for 3264 hours according to a UV-C lifetime test. The absorbance spectra are shown in Figure 3A, with reference number 34 indicating the unexposed film after zero hours of UV-C exposure, and reference number 35 indicating the film after 3264 hours of UV-C exposure.

[0179] Another sample of this film was similarly exposed to 222 nm UV-C radiation for 672 hours according to a UV-C lifetime test. The absorbance spectra are shown in Figure 3B, with reference numeral 36 indicating the unexposed film after zero hours of UV-C exposure and reference numeral 37 indicating the film after 672 hours of UV-C exposure. There are no signs of degradation or loss of light transmittance. THV815 has a melting point of 225°C and does not adhere to surfaces heated to 150°C.

[0180] Base film example 2 A 12 mil (300 micrometer) thick THV221 film manufactured by 3M Company (St. Paul, MN) was exposed to 254 nm UV-C radiation for 3264 hours according to a UV-C lifetime test. The absorbance spectra are shown in Figure 3C, with reference numeral 38 indicating the unexposed film after zero hours of UV-C exposure, and reference numeral 39 indicating the film after 3264 hours of UV-C exposure. There were no signs of degradation or loss of light transmittance. THV221 has a melting point of 130°C and can be heat-sealed at 140°C.

[0181] Narrowband bandpass filter UV-C mirror film Narrowband bandpass filter UV-C mirror film Example 1 A multilayer UV-C protective mirror film was fabricated by vapor coating an inorganic optical laminate, having a first optical layer containing HfO2 and a second optical layer containing SiO2, onto a 100 micrometer (4 mil) thick fluoropolymer film substrate (obtained from Nowofol Kunststoffprodukte GmbH KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV815"). More specifically, a thin film laminate consisting of 13 alternating layers of HfO2 and SiO2, designed to have a peak reflectivity at 254 nm, was prepared using the following method.

[0182] This method began with coating Layer 1, a 30.00 nm thick layer of HfO2, using electron beam deposition. Four hearths were used as deposition sources for the electron beam deposition. Each hearth was conical in shape and had a volume of 17 cm³. 3 The material was filled with HfO2 blocks. A magnetically deflected high-voltage electron beam was raster-scanned across the material surface in a pre-programmed manner, while steadily increasing the beam filament current.

[0183] Upon completion of the pre-programmed process, the HFO2 surface was heated to its evaporation temperature of approximately 2500°C. The supply source shutter was opened, and the HfO2 vapor flux ejected from the supply source in a cosine distribution, condensing on the substrate material above the supply source. To improve coating uniformity, the substrate holder was rotated during deposition. Once the specified coating thickness (30.00 nm) was reached, the filament current was cut off, the shutter was closed, and the HfO2 material was cooled.

[0184] Next, coating layer 2 was deposited directly onto coating layer 1. For coating layer 2, the deposition source was then replaced with a hearth containing a mass of SiO2, and a similar pre-programmed heating process was initiated. In this case, the surface temperature of the SiO2 was approximately 950°C when the supply source shutter was opened, and when the specified coating thickness (45.02 nm) was reached, the filament current was cut off, the shutter was closed, and the HfO2 material was cooled.

[0185] This stepwise alternating layering process was continued layer by layer until a total of 13 layers were reached (seven layers of HfO2 and six layers of SiO2). The reflectance spectrum of this multilayer UV-C protective mirror film was measured using a spectrophotometer (obtained from Shimadzu (Kyoto, Japan) under the trade name "Shimadzu 2550 UV-VIS"). The resulting reflectance spectrum 50 is shown in Figure 4.

[0186] Modeled hypothetical example I Using the Berreman method described in the Journal of the Optical Society of America (Volume 62, Number 4, April 1972) and the Journal of Applied Physics (Volume 85, Number 6, March 1999), we calculated the % reflectance spectrum shown in Figure 5 for a multilayer optical film having 14 alternating optical layers, consisting of a first layer of high refractive index ZrON and a second layer of low refractive index SiO2, with a target reflectance median of 254 nm at a perpendicular incident light angle (0°). For this hypothetical UV-C reflective multilayer optical film, we calculated the % reflectance spectra for incident light angles of 0° (spectrum 71), 10° (spectrum 72), 20° (spectrum 73), 30° (spectrum 74), and 40° (spectrum 75).

[0187] Modeled hypothetical example II This UV-C radiation reflection protective film includes a multilayer optical film comprising a first optical layer made of PVDF (polyvinylidene fluoride) (available from Dyneon LLC (Oakdale, MN) under the trade name "PVDF 6008") and a second optical layer containing a fluoropolymer (available from Dyneon LLC (Oakdale, MN) under the trade name "THV815GZ"). A 254-layer optical laminate can be formed by co-extruding the PVDF ("PVDF 6008") and the fluoropolymer ("THV815GZ") through a multilayer melt manifold.

[0188] The layer thickness profile (layer thickness value) of this UV-C radiation reflection protective film can be adjusted to produce a nearly linear profile, where, when reflection is measured at an incident light angle of 0° (perpendicular angle), the thinnest layer is adjusted to have an optical thickness (refractive index × physical thickness) of approximately 1 / 4 wavelength for 200 nm light, and progresses to the thickest layer which is adjusted to have an optical thickness of approximately 1 / 4 wavelength for 300 nm light.

[0189] Using the Berreman method described in the Journal of the Optical Society of America (Volume 62, Number 4, April 1972) and the Journal of Applied Physics (Volume 85, Number 6, March 1999), the % reflectance spectrum shown in Figure 6 was calculated for a multilayer optical film having a total of 254 layers (127 PVDF high-refractive-index optical layers and 127 TVH815 low-refractive-index layers, each high-refractive-index layer alternating with a low-refractive-index layer), and targeting a median reflectance value of 250 nm at a perpendicular incident light angle (0°).

[0190] Broadband bandpass filter UV-C mirror film Broadband bandpass filter UV-C (UV-B reflective [protective] mirror film) Example 2 - ZrO x N y :SiAl x O ZrO x N y A first optical layer containing SiAl x O y An inorganic optical laminate having a second optical layer containing [a specific component] was sputter-coated onto a 4 mil (100 micrometer) thick fluoropolymer film (obtained from Nowofol Kunststoffprodukte GmbH&Co.KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV 815") to create a broadband UV-C protective mirror film that reflects over the range of 240-310 nm.

[0191] ZrO x N y SiAl is used as a low refractive index material. x O yA UV transparent film was coated using a continuous roll-to-roll (R2R) method. The optical design was such that layers of the two materials, each with a quarter-wavelength thickness, were arranged alternately with a layer thickness gradient, with the gradient adjusted so that reflection began at 240 nm and ended at 310 nm at the final thickness. ZrO has a refractive index of 2.25 at 254 nm. x N y Regarding this, the target physical thickness was set at 24.66 nm. In this case, SiAl with a refractive index of 1.49 is sputtered from an aluminum-doped silicon sputtering target. x O y Regarding this, the target thickness was set at 37.23 nm.

[0192] ZrO in layer 1 x N y The film was DC sputtered from a pure zirconium sputtering target in a gas mixture of argon, oxygen, and nitrogen. While argon was the primary sputtering gas, the levels of oxygen and nitrogen were set to achieve transparency, low absorptivity, and high refractive index. The film roll was initially transported at a predetermined speed, and after the sputtering source output increased to its maximum operating output, the reactive gas was introduced, followed by the attainment of steady-state conditions. The sputtering source was perpendicular to the film being coated and wider than the film. When the coated film reached the desired length, the reactive gas was set to zero, and the target was sputtered to obtain a pure Zr surface state.

[0193] Next, the film orientation was reversed, and AC frequency (40 kHz) power was applied to the (aluminum-doped) silicon, which formed the replacement pair for the sputtering target, in an argon sputtering atmosphere. Once a steady state was reached, a reactive gas of oxygen was introduced to provide transparency and a low refractive index. The second layer was coated over the length coated with respect to layer 1, using predetermined process settings and line speed. The sputtering source was perpendicular to the film being coated and wider than the film.

[0194] After the coated film reached the desired length, reactive oxygen was removed, and the target was sputtered in argon to obtain the surface state of pure (aluminum-doped) silicon. This stepwise process was continued layer by layer until a total of nine layers were reached. The resulting peak reflectance, measured with a spectrophotometer (obtained from Perkin Elmer Instruments (Waltham, MA) under the trade name "LAMBDA 1050 UV-VIS"), was 95% at 254 nm, indicating that the film transmitted 80% of UV-C radiation at 222 nm.

[0195] Broadband UV-C bandpass filter (UV-B + UV-A reflective [protective] mirror film) Example 3 (ZrO x N y / SiAl x O y ) ZrO x N y A first optical layer containing SiAl x O y An inorganic optical laminate having a second optical layer containing [a specific component] was sputter-coated onto a 4 mil (100 micrometer) thick fluoropolymer film (obtained from Nowofol Kunststoffprodukte GmbH KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV 815") to create a broadband UV-C protective mirror film that reflects over the range of 240-310 nm.

[0196] ZrO x N y SiAl is used as a low refractive index material. x O yA UV transparent film was coated using a continuous roll-to-roll (R2R) method. The optical design was such that layers of the two materials, each with a quarter-wavelength thickness, were arranged alternately with a layer thickness gradient, with the gradient adjusted so that reflection began at 240 nm and ended at 310 nm at the final thickness. ZrO has a refractive index of 2.25 at 254 nm. x N y For this, the target physical thickness was set at 24.66 nm. In this case, for SiAlxOy with a refractive index of 1.49, which is sputtered from an aluminum-doped silicon sputtering target, the target thickness was set at 37.23 nm.

[0197] ZrO in layer 1 x N y The film was DC sputtered from a pure zirconium sputtering target in a gas mixture of argon, oxygen, and nitrogen. While argon was the primary sputtering gas, the levels of oxygen and nitrogen were set to achieve transparency, low absorptivity, and high refractive index. The film roll was initially transported at a predetermined speed, and after the sputtering source output increased to its maximum operating output, the reactive gas was introduced, followed by the attainment of steady-state conditions. The sputtering source was perpendicular to the film being coated and wider than the film. When the coated film reached the desired length, the reactive gas was set to zero, and the target was sputtered to obtain a pure Zr surface state.

[0198] Next, the film orientation was reversed, and power at an AC frequency (40 kHz) was applied to the (aluminum-doped) silicon, which formed the replacement pair for the sputtering target, in an argon sputtering atmosphere. Once a steady state was reached, a reactive gas of oxygen was introduced to provide transparency and a low refractive index. The second layer was coated over the length coated with respect to layer 1 at predetermined process settings and line speed. The sputtering source was perpendicular to the film being coated and wider than the film. After the coated film reached the desired length, the reactive oxygen was removed, and the target was sputtered in argon to obtain the surface state of pure (aluminum-doped) silicon.

[0199] This stepwise process was continued layer by layer until a total of nine layers were reached. The resulting peak reflectance was measured at 95% at 254 nm using a spectrophotometer ("LAMBDA 1050 UV-VIS").

[0200] A UV-B mirror film reflecting in the 310-360 nm range was fabricated by co-extruding a first optical layer made of PMMA (obtained from Altuglas International, Arkema Inc. (Bristol, PA) under the trade name "PLEXIGLAS V044") with a second optical layer made of fluoropolymer 2 (obtained from Dyneon LLC (Oakdale, MN) under the trade name DYNEON THV 221GZ). A laminate of 275 optical layers was formed by co-extruding PMMA and fluoropolymer 2 via a multilayer polymer melt manifold.

[0201] The layer thickness profile (layer thickness value) of this UV-B mirror film was adjusted to be a nearly linear profile, with the first (thinnest) optical layer having an optical thickness (refractive index × physical thickness) of approximately 1 / 4 wavelength for 310 nm light, progressing to the thickest layer, which has an optical thickness of approximately 1 / 4 wavelength for 360 nm light. The layer thickness profile of this film was adjusted in combination with layer profile information obtained by atomic force microscopy techniques using an axial rod apparatus taught in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference, to provide improved spectral characteristics.

[0202] Furthermore, non-optical protective skin layers (each 100 micrometers thick) made of PMMA were co-extruded onto both sides of the optical laminate. This co-extruded multilayer molten flow was cast onto a cooling roll at 5.4 meters per minute to create a multilayer cast web approximately 400 micrometers thick. This multilayer cast web was then preheated at 120°C for approximately 10 seconds and biaxially stretched in both the mechanical (downweb) and transverse (crossweb) directions at a stretch ratio of 3.0 (to orient the film). When this UV-B reflective multilayer film was measured with a spectrophotometer (Perkin Elmer's "LAMBDA 1050 UV-VIS"), it reflected 95% of UV-B radiation across a bandwidth of 310 nm to 360 nm.

[0203] A UV-A mirror film reflecting in the 340-390 nm range was fabricated by co-extruding a first optical layer made of PMMA (obtained from Altuglas International, Arkema Inc. (Bristol, PA) under the trade name "PLEXIGLAS V044") with a second optical layer made of fluoropolymer 2 (obtained from Dyneon LLC (Oakdale, MN) under the trade name "DYNEON THV 221GZ"). A laminate of 275 optical layers was formed by co-extruding PMMA and fluoropolymer 2 through a multilayer polymer melt manifold.

[0204] The layer thickness profile (layer thickness value) of this UV-B mirror film was adjusted to be a nearly linear profile, with the first (thinnest) optical layer having an optical thickness (refractive index × physical thickness) of approximately 1 / 4 wavelength for 340 nm light, and progressing to the thickest layer, which has an optical thickness of approximately 1 / 4 wavelength for 390 nm light. The layer thickness profile of this film was adjusted in combination with layer profile information obtained by atomic force microscopy techniques using an axial rod apparatus taught in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference, to provide improved spectral characteristics.

[0205] Furthermore, non-optical protective skin layers (each 100 micrometers thick) made of PMMA were co-extruded onto both sides of the optical laminate. This co-extruded multilayer molten flow was cast onto a cooling roll at 5.0 meters per minute to create a multilayer cast web approximately 435 micrometers thick. This multilayer cast web was then preheated at 120°C for approximately 10 seconds and biaxially stretched in both the mechanical (downweb) and transverse (crossweb) directions at a stretch ratio of 3.0 (to orient the film). When this UV-A reflective multilayer film was measured with a spectrophotometer (Perkin Elmer's "LAMBDA 1050 UV-VIS"), it reflected 95% of UV-A radiation across a bandwidth of 340 nm to 390 nm.

[0206] These 240–310 nm UV-C mirror films, 310–360 nm UV-B mirror films, and 340–390 nm UV-A mirror films were heat-laminated in a 130°C oven under a weight of 5 pounds (2.27 kg) for 2 hours. The reflectance spectra of these heat-laminated UV mirror film laminates were measured using a spectrophotometer (Perkin Elmer's "LAMBDA 1050 UV-VIS"). The laminated broadband UV-C protective mirror films exhibited an average % reflectance of 85% over the wavelength range of 240 nm to 390 nm, as shown by the reflectance spectra in Figure 7.

[0207] Broadband UV-C bandpass filter (UV-B + UV-A reflective [protective] mirror film) Example 4 (HfO2:SiO2 / ZrO x N y :SiAl x O y ) A broadband UV-C protective mirror film reflecting over the 215-280 nm range was fabricated by vapor coating an inorganic optical laminate, having a first optical layer containing HfO2 and a second optical layer containing SiO2, onto a 100 micrometer (4 mil) thick fluoropolymer film (obtained from Nowofol Kunststoffprodukte GmbH KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV 815").

[0208] More specifically, the experiment began by coating a thin film laminate, composed of alternating layers of HfO2 and SiO2 and designed to have a peak reflectivity at 254 nm, with HfO2 layer 1 at 30.00 nm. For electron beam deposition, four hearths were used as deposition sources. Each hearth was conical in shape and had a volume of 17 cm³. 3 The material was filled with HfO2 blocks. A magnetically deflected high-voltage electron beam was raster-scanned across the material surface in a pre-programmed manner, while steadily increasing the beam filament current.

[0209] Upon completion of the pre-programmed process, the HfO2 surface was heated to its evaporation temperature of approximately 2500°C. The supply source shutter was opened, and the HfO2 vapor flux was ejected from the supply source in a cosine distribution, condensing on the substrate material above the supply source. To improve coating uniformity, the substrate holder was rotated during deposition. Once the specified coating thickness (30.00 nm) was reached, the filament current was cut off, the shutter was closed, and the HfO2 material was cooled.

[0210] For layer 2, the deposition source was then replaced with a hearth containing a mass of SiO2, and a similar pre-programmed heating process was initiated. In this case, the surface temperature of the SiO2 was approximately 950°C when the supply source shutter was opened, and once the specified coating thickness (45.02 nm) was reached, the filament current was cut off, the shutter was closed, and the SiO2 material was cooled.

[0211] This stepwise process was continued layer by layer until a total of 13 layers were reached. The resulting peak reflectance, measured with a spectrophotometer (obtained from Shimadzu Corp. (Kyoto, Japan) under the product name "SHIMADZU UV-2550 UV-VIS"), was found to be 95% at 222 nm.

[0212] Next, this UV-C mirror film reflecting in the 215–280 nm range was heat-laminated in a 130°C oven to the heat-laminated UV mirror film laminate described in Example 3 under a weight of 5 pounds (2.27 kg) for 2 hours. The laminated broadband UV-C protective mirror film exhibited an average % reflectance of 85.6% over the wavelength range of 215 nm–390 nm, as shown by the reflectance spectrum in Figure 8.

[0213] Modeled hypothetical example III By co-extruding a first optical layer made of fluoropolymer 1 (available from Dyneon LLC (Oakdale, MN) under the trade name "DYNEON FLUOROPLASTIC PVDF 6008") with a second optical layer made of fluoropolymer 2 (available from Dyneon LLC (Oakdale, MN) under the trade name "DYNEON THV 221GZ"), it was possible to produce a broadband UV-C protective mirror film that reflects in the range of 260 to 390 nm.

[0214] A laminate of 275 optical layers is formed by co-extruding fluoropolymer 1 and fluoropolymer 2 through a multilayer polymer melt manifold. The layer thickness profile (layer thickness value) of this broadband UV-C mirror film is adjusted to be a nearly linear profile, with the first (thinnest) optical layer having an optical thickness (refractive index × physical thickness) of approximately 1 / 4 wavelength for 260 nm light, and progressing to the thickest layer, which has an optical thickness of approximately 1 / 4 wavelength for 390 nm light.

[0215] The layer thickness profile of this film is adjusted to provide improved spectral characteristics in combination with layer profile information obtained by atomic force microscopy techniques using an axial rod apparatus taught in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference.

[0216] Furthermore, non-optical protective skin layers, each made of fluoropolymer 1 (100 micrometers thick), were co-extruded onto both sides of the optical laminate. This co-extruded multilayer molten flow was cast onto a cooling roll at 5.4 meters per minute to create a multilayer cast web approximately 400 micrometers thick.

[0217] Next, this multilayer cast web is preheated at 120°C for approximately 10 seconds and biaxially stretched in both the mechanical (downweb) and transverse (crossweb) directions at a stretch ratio of 3.0 (to orient the film). This UV-reflective multilayer film is expected to reflect 95% of UV light across a bandwidth of 260 nm to 390 nm, as measured by a spectrophotometer (Perkin Elmer's "LAMBDA 1050 UV-VIS").

[0218] A broadband UV-C mirror film is fabricated by vapor coating a UV-C film, which has an inorganic optical laminate that reflects in the range of 210-270 nm and has a first optical layer containing HfO2 and a second optical layer containing SiO2, onto the aforementioned 260-390 nm fluoropolymer UV mirror film. More specifically, a thin film laminate composed of alternating layers of HfO2 and SiO2, designed to have a peak reflectivity at 240 nm, is started by coating layer 1 with HfO2 at 30.00 nm. In electron beam deposition, a four-hearth deposition source is used. Each hearth is conical in shape and has a volume of 17 cm³. 3 It was decided to fill it with HfO2 blocks.

[0219] A magnetically deflected high-voltage electron beam is raster-scanned across the material surface in a pre-programmed manner, steadily increasing the beam's filament current. Upon completion of the pre-programmed process, the HfO2 surface is heated to its evaporation temperature of approximately 2500°C. The supply source shutter opens, and the HfO2 vapor flux is ejected from the supply source in a cosine distribution, condensing on the substrate material above the supply source. To improve coating uniformity, the substrate holder was rotated during the deposition process.

[0220] When the specified coating thickness (30.00 nm) is reached, the filament current is cut off, the shutter closes, and the HfO2 material is cooled. For layer 2, the deposition source is then replaced with a hearth containing a mass of SiO2, and a similar pre-programmed heating process is initiated. In this case, the surface temperature of the SiO2 reaches approximately 950°C when the supply source shutter opens, and when the specified coating thickness (45.02 nm) is reached, the filament current is cut off, the shutter closes, and the SiO2 material is cooled.

[0221] This stepwise process is continued layer by layer until a total of 13 layers are reached. The resulting peak reflectance is measured with a spectrophotometer (available from Shimadzu Corp. (Kyoto, Japan) under the trade name "SHIMADZU UV-2550 UV-VIS") and is expected to reflect at least 90% of UV light across a bandwidth of 210 nm to 390 nm.

[0222] Modeled hypothetical example IV By co-extruding a first optical layer made of fluoropolymer 1 (available from Dyneon LLC (Oakdale, MN) under the trade name "DYNEON FLUOROPOLYMER PVDF 6008") with a second optical layer made of fluoropolymer 3 (available from Dyneon LLC (Oakdale, MN) under the trade name "DYNEON THV 815GZ"), it was possible to produce a broadband UV-C protective mirror film that reflects in the range of 240 to 390 nm.

[0223] A laminate of 550 optical layers is formed by co-extruding fluoropolymer 1 and fluoropolymer 3 through a multilayer polymer melt manifold. The layer thickness profile (layer thickness value) of this UV-C mirror film is adjusted to be a nearly linear profile, with the first (thinnest) optical layer having an optical thickness (refractive index × physical thickness) of approximately 1 / 4 wavelength for 240 nm light, and progressing to the thickest layer, which has an optical thickness of approximately 1 / 4 wavelength for 390 nm light.

[0224] The layer thickness profile of this film is adjusted to provide improved spectral characteristics in combination with layer profile information obtained by atomic force microscopy techniques using an axial rod apparatus taught in U.S. Patent No. 6,783,349 (Neavin et al.), the entire disclosure of which is incorporated herein by reference.

[0225] Furthermore, non-optical protective skin layers, each made of fluoropolymer 1 (100 micrometers thick), are co-extruded onto both sides of the optical laminate. This co-extruded multilayer molten flow is cast onto a cooling roll at 5.4 meters per minute to create a multilayer cast web approximately 400 micrometers thick. This multilayer cast web is then preheated at 120°C for approximately 10 seconds and biaxially stretched in both the mechanical (downweb) and transverse (crossweb) directions at a stretch ratio of 3.0 (to orient the film).

[0226] This broadband UV-C reflective multilayer film is expected to reflect 99% of UV light across a wavelength band of 240nm to 390nm and transmit more than 80% of UV light across a wavelength band of 215nm to 230nm, as measured by a spectrophotometer (Perkin Elmer's "LAMBDA 1050 UV-VIS").

[0227] Example 5 ZrO x Ny A first optical layer containing SiAl x O y An inorganic optical laminate having a second optical layer containing a certain material was sputter-coated onto a 100 mil (4 micrometer) thick fluoropolymer film (obtained from Nowofol Kunststoffprodukte GmbH&Co.KG (Siegsdorf, Germany) under the trade name "NOWOFLON THV 815") to create a UV-C mirror film that reflects in the range of 240-310 nm. ZrO was used as the high refractive index material. x N y SiAl is used as a low refractive index material. x O y Using this method, a visible light transparent UV-C mirror film was coated using a continuous roll-to-roll (R2R) method.

[0228] The optical design was such that layers of the two materials, each one-quarter wavelength thick, were arranged alternately with a gradient in layer thickness, with the gradient adjusted so that reflection began at 240 nm and ended at 310 nm at the final thickness. ZrO has a refractive index of 2.25 at 254 nm. x N y Regarding this, the target physical thickness was set at 24.66 nm. In this case, SiAl with a refractive index of 1.49 is sputtered from an aluminum-doped silicon sputtering target. x O y Regarding this, the target thickness was set at 37.23 nm. ZrO in layer 1 x N y The material was DC sputtered from a pure zirconium sputtering target in a gas mixture of argon, oxygen, and nitrogen. While argon was the primary sputtering gas, the levels of oxygen and nitrogen were set to achieve transparency, low absorptivity, and high refractive index.

[0229] The film roll was initially transported at a predetermined speed, and after the sputtering source output increased to its maximum operating output, the reactive gas was introduced, and then the steady-state conditions were reached. The sputtering source was perpendicular to the film being coated and wider than the film. When the coated film reached the desired length, the reactive gas was set to zero, and the target was sputtered to obtain a pure Zr surface.

[0230] Next, the film orientation was reversed, and power at an AC frequency (40 kHz) was applied to the (aluminum-doped) silicon, which formed the replacement pair for the sputtering target, in an argon sputtering atmosphere. Once a steady state was reached, a reactive gas of oxygen was introduced to provide transparency and a low refractive index. The second layer was coated over the length coated with respect to layer 1 at predetermined process settings and line speed. The sputtering source was perpendicular to the film being coated and wider than the film. After the coated film reached the desired length, the reactive oxygen was removed, and the target was sputtered in argon to obtain the surface state of pure (aluminum-doped) silicon.

[0231] This stepwise process was continued layer by layer until a total of nine layers were reached. The resulting peak reflectance, measured with a spectrophotometer (obtained from Perkin Elmer Instruments (Waltham, MA) under the trade name "LAMBDA 1050 UV-VIS"), was 95% at 254 nm, indicating that the film transmitted 80% of 222 nm UV-C radiation.

[0232] Comparative Example 4 A printed circuit board measuring 8 cm wide by 16 cm long was fabricated, featuring six 265 nm UV-C LEDs available from Crystal ISC, spaced 2.5 cm wide and 5 cm long, as shown in Figure 1. A prototype "control" box with internal dimensions of 8 cm wide by 16 cm long by 1 cm deep and external dimensions of 10 cm wide by 18 cm long by 2 cm deep was fabricated from poster form board (available from Office Depot (Maplewood, MN)). Two 1.5 cm diameter holes were drilled in the bottom of this prototype box for UV-C intensity measurement using a Thorlabs UV-C radiometer. One of the holes in the bottom of the prototype box was positioned directly below one of the UV-C LEDs, and the other hole was positioned centered between the UV-C LEDs.

[0233] With each LED supplied with 40mA of power, the Thorlabs sensor measured a UV-C intensity of 119 microwatts at 265nm directly beneath one of the UV-C LEDs. With each LED supplied with 40mA of power, the Thorlabs sensor measured 9.6 microwatts when positioned centered between the LEDs.

[0234] Example 6 A prototype box similar to that in Comparative Example 4 was fabricated, and the UV-C mirror film described in Example 5 was attached to the inner surface using an optically transparent adhesive, OCA8171 (available from 3M Company), as shown in Figure 2. The UV-C mirror film described in Example 5 was also attached to the flat space between UV-C LEDs on the printed circuit board using OCA8171.

[0235] With each LED supplied with 40mA of power, the Thorlabs sensor measured a UV-C intensity of 118 microwatts at 265nm directly beneath one of the UV-C LEDs. With each LED supplied with 40mA of power, the Thorlabs sensor measured 33 microwatts when positioned centered between the LEDs.

[0236] Descriptions of elements in the figures should be understood to apply equally to corresponding elements in other figures unless otherwise indicated. While specific embodiments have been illustrated and described herein, those skilled in the art will understand that any particular embodiment illustrated and described can be replaced by a variety of alternative and / or equivalent implementations without departing from the scope of this disclosure. This application is intended to encompass any adaptation or modification of any particular embodiment discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

[0237] Throughout this specification, any reference to “one embodiment,” “a particular embodiment,” “one or more embodiments,” or “a certain embodiment,” whether or not the term “exemplary” precedes the term “embodiment,” means that any specific feature, structure, material, or property described in relation to that embodiment is included in at least one of the particular exemplary embodiments of this disclosure. Therefore, throughout this specification, the appearance of phrases such as “in one or more embodiments,” “in a particular embodiment,” “in one embodiment,” or “in an embodiment” in various places does not necessarily refer to the same embodiment among the particular exemplary embodiments of this disclosure. Furthermore, specific features, structures, materials, or properties can be combined in any preferred manner in one or more embodiments.

[0238] While this specification has described in detail certain exemplary embodiments, those skilled in the art will understand that modifications, variations, and equivalents of these embodiments can be easily conceived upon understanding the foregoing description. Therefore, it should be understood that this disclosure is not excessively limited to the exemplary embodiments described above. In particular, when used herein, an enumeration of numerical ranges by endpoints is intended to include all numbers encompassed within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). Furthermore, all numbers used herein are assumed to be modified by the term “about”.

[0239] Furthermore, all publications and patents referenced herein are incorporated by reference in whole to the same extent as when each individual publication or patent is specifically and individually indicated to be incorporated by reference. In the event of any inconsistency or contradiction between the incorporated references and this application, the information in the foregoing description shall prevail.

[0240] Various exemplary embodiments have been described. These embodiments and other embodiments are within the scope of the following claims.

Claims

1. It is a device, A housing that is impermeable to ultraviolet radiation having wavelengths of 280 nm to 400 nm, and at least one window defined within the housing, the window comprising a UV-C radiation bandpass mirror film composed of a plurality of alternately arranged first optical layers and second optical layers that transmit UV-C radiation with wavelengths of 190 nm to 230 nm but do not transmit UV-A radiation and UV-B radiation with wavelengths of 280 nm to 400 nm, The device comprises an ultraviolet radiation source positioned inside the housing, which is capable of emitting ultraviolet radiation of one or more wavelengths between 100 nm and 400 nm, and the device is A device comprising an ultraviolet mirror film attached to the inner wall of the housing so as to reflect ultraviolet radiation emitted by the ultraviolet radiation source and guide it to the window, the ultraviolet mirror film comprising at least a plurality of alternately arranged first optical layers and second optical layers that reflect at least 50 percent of incident UV-C ultraviolet radiation in the wavelength range of 190 nm to 230 nm and transmit at least 50 percent of incident ultraviolet radiation in the wavelength range of 230 nm to 400 nm, wherein at least 50 percent of ultraviolet radiation having a wavelength of at least 230 nm to 400 nm transmitted through the ultraviolet mirror film is absorbed by the housing.

2. The device according to claim 1, wherein the housing has a hollow, non-planar shape, and further, the ultraviolet radiation source is surrounded by the housing.

3. The device according to claim 1, wherein the UV-C radiation bandpass mirror film comprises at least a first optical layer comprising at least one of zirconium oxynitride, hafnia, alumina, magnesium oxide, yttrium oxide, lanthanum fluoride, or neodymium fluoride, and at least a second optical layer comprising at least one of silica, aluminum fluoride, magnesium fluoride, calcium fluoride, silica-alumina oxide, or alumina-doped silica.

4. The device according to claim 1, wherein the ultraviolet mirror film is separated from the ultraviolet radiation source by an air gap.

5. A method for disinfecting at least one material, To supply the device described in any one of claims 1 to 4, The ultraviolet radiation emitted by the aforementioned ultraviolet radiation source is directed through the aforementioned UV-C radiation bandpass mirror film, A method comprising exposing the at least one material to ultraviolet radiation passing through the UV-C radiation bandpass mirror film for a period of time sufficient to achieve a desired degree of disinfection of the at least one material.

Images