Radiative cooling article comprising a white diffuse reflective layer and a non-white color mirror

Abstract

The present disclosure provides a radiative cooling article comprising a white diffuse reflective microporous layer and a non-white color mirror film having a first optical layer and a second optical layer. The white diffuse reflective microporous layer has a solar-weighted reflectance of 0.8 or greater, 0.85, 0.9, or 0.95 or greater for normally incident electromagnetic radiation having a wavelength in the range of 350 nanometers (nm) to 2500 nm. The non-white color reflective film is disposed proximate a major surface of the white diffuse reflective microporous layer and the non-white color reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm. The non-white color reflective film can be tuned to reflect a specific color of light (e.g., blue, green, or red light). The radiative cooling article can be used in applications including commercial graphics located outdoors (e.g., on a vehicle or a building). The present disclosure also provides a composite cooling article comprising a radiative cooling article attached to a vehicle or trailer. Further, the present disclosure provides a multi-surface passive cooling article comprising a first element and a second element, wherein at least one of the elements comprises a radiative cooling article.

Description

Technical Field

[0001] This disclosure relates in general to passive radiation cooling products. Background Technology

[0002] Passive radiative cooling without an external energy source could be attractive for reducing the power required in cooling applications such as refrigeration, air conditioning, vehicles, power transformers, and communication antennas. Surface material properties for passive radiative cooling during the day include low emissivity in the solar wavelength range of 0.3 to 2.5 micrometers and high emissivity in the infrared wavelength range of 3 to 20 micrometers. For cooling a surface below air temperature via passive radiative cooling, the surface can have high emissivity in the infrared wavelength range of 8 to 13 micrometers, but not high emissivity in the wavelength range of 3 to 8 micrometers (or 13 to 20 micrometers). According to Kirchhoff's law of thermal radiation, high emissivity is associated with high absorbance. The orientation of the radiatively cooled surface relative to the sky, especially on vertical surfaces, can affect performance. Some studies have been conducted on the ability to perform passive cooling during the day. Several cooling plates made from films for passive cooling have been described. Further development of passive radiative cooling technology would be ideal. Summary of the Invention

[0003] In a first aspect, a radiation-cooled article is provided. The radiation-cooled article includes a white diffuse-reflective microporous layer; and a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers. The white diffuse-reflective microporous layer has a solar-weighted reflectivity of 0.8 or greater, 0.85, 0.9, or 0.95 or greater for vertically incident electromagnetic radiation with most wavelengths in the range of 350 nanometers (nm) to 2500 nm. The non-white colored reflective film is disposed adjacent to the main surface of the white diffuse-reflective microporous layer and reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm. The non-white colored reflective film can be tuned to reflect light of a specific color (e.g., blue, green, or red). The radiation-cooled article can be used in applications including commercial graphics located outdoors (e.g., on buildings or vehicles, such as buses, cars, trucks, or trains).

[0004] In a second aspect, a composite cooling system is provided. This composite cooling system includes a radiant cooling article according to the first aspect, attached to a vehicle or trailer.

[0005] In a third aspect, a multi-surface passive cooling article is provided. The multi-surface passive cooling article includes a plurality of first elements defining an outer surface of a first element, the plurality of first elements having a first absorbance greater than or equal to 0.6 in an atmospheric window wavelength range of 8 to 13 micrometers, and a first average reflectance greater than or equal to 80% in a solar wavelength range of 0.4 to 2.5 micrometers. At least one of these first elements includes a radiative cooling layer comprising: a) a white diffuse microporous layer having a solar-weighted reflectivity of 0.8 or greater, 0.85, 0.9, or 0.95 or greater for vertically incident electromagnetic radiation in the wavelength range of 350 nm to 2500 nm; and b) a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse microporous layer, wherein the non-white colored reflective film reflects at least a wavelength bandwidth of 30 nm in the wavelength range of 350 nm to 700 nm. The multi-surface passive cooling article also includes a plurality of second elements defining the outer surface of the second elements, the plurality of second elements defining a second absorbance of less than or equal to 0.5 in the atmospheric window wavelength range and a second average reflectivity of greater than or equal to 60% in the solar wavelength range. A plurality of first elements and a plurality of second elements are dispersed to form a main structure having a first main surface including outer surfaces of the first elements and outer surfaces of the second elements, and a second main surface opposite to the first main surface. The main structure has a first end region and a second end region, wherein the outer surfaces of the first elements face a first direction toward the first end region, and the outer surfaces of the second elements face a second direction toward the second end region. Attached Figure Description

[0006] Figure 1 This is a schematic cross-sectional view of an exemplary radiation-cooled article that can be prepared according to this disclosure.

[0007] Figure 2 This is a schematic cross-sectional view of another exemplary radiation-cooled article that can be prepared according to this disclosure.

[0008] Figure 3 This is a schematic side view of an exemplary multilayer optical film.

[0009] Figure 4A , Figure 4B and Figure 4C A view of a stain-resistant surface structure with microstructure. Figure 4A A perspective view of the cross-section relative to the xyz axes is shown. Figure 4C It shows Figure 4A Cross-section in the xz plane. Figure 4B Another cross section in the yz plane is shown.

[0010] Figure 5 for Figures 4A to 4C Cross-sectional views of various nanostructures of the antifouling surface structure in the xz plane.

[0011] Figure 6 These are cross-sectional views of various nanostructures comprising masking elements in the xz plane, which can be compared with... Figures 4A to 4C The anti-fouling surface structure is used together Figure 5 An alternative to nanostructures.

[0012] Figure 7A and Figure 7B The diagram shows a line representing the cross-sectional profile of different forms of microstructures used for antifouling surface structures in the xz plane.

[0013] Figure 8 A perspective view of a portion of a first antireflective surface structure having a discontinuous microstructure.

[0014] Figure 9 A perspective view of a portion of a second antifouling surface structure having a discontinuous microstructure.

[0015] Figure 10 and Figure 11 A perspective view of different parts of a third antireflective surface structure with a discontinuous microstructure.

[0016] Figure 12A It is a schematic side view of a composite cooling system including a radiation-cooled product and a substrate.

[0017] Figure 12B It is a schematic top view of a composite cooling system that includes radiative cooling components on a vehicle.

[0018] Figure 13A This is a top view of the surface of the outer layer of a radiation-cooled product.

[0019] Figures 13B to 13E It can be used Figure 13A Illustrations of various surface structures of the surface shown.

[0020] Figure 14 This is a schematic cross-sectional view of one embodiment of a multi-surface passive cooling article.

[0021] Figure 15 This is a schematic cross-sectional view of another embodiment of a multi-surface passive cooling article.

[0022] Figure 16This is a graph describing an embodiment of the energy spectrum of solar energy (or sunlight) in the atmospheric window region, the energy transmittance % spectrum of a ground reference spectrum present in ASTM G173-03 (2012), and the absorption of a high emissivity element in a multi-surface passive cooling product.

[0023] Figure 17 This is a schematic cross-sectional view of a specific embodiment of a multi-surface passive cooling article.

[0024] Figure 18 This is a photograph of an exemplary radiation-cooled article prepared in Example 3.

[0025] Figure 19 This is a schematic side view of the recovery chamber model of Examples 4 to 6.

[0026] Figure 20 The graphs show the simulated reflection spectra of the multilayer optical film in Example 4 at incident angles of 0°, 30°, and 60°.

[0027] Figure 21 The graphs show the simulated reflection spectra of the multilayer optical film in Example 5 at incident angles of 0°, 30°, and 60°.

[0028] Figure 22 The graphs show the simulated reflection spectra of the multilayer optical film in Example 6 at incident angles of 0°, 30°, and 60°. Detailed Implementation

[0029] Glossary

[0030] As used in this article, "majority" means more than 50%.

[0031] As used herein, the term “copolymer” refers to a polymer formed from two or more different monomers.

[0032] As used in this article, "fluoropolymer" refers to any organic polymer that contains fluorine.

[0033] As used in this article, "non-fluorinated" means that it does not contain fluorine.

[0034] As used herein, “adjacent” includes direct contact (e.g., direct adjacency) and the presence of one or more intermediate layers between adjacent materials.

[0035] As used herein, “fixed to” means directly or indirectly attached to (e.g., in direct contact or bonded to by an integral adhesive layer).

[0036] As used in this article, “incident” relative to light refers to light falling on or shining onto a material.

[0037] As used herein, “microporous” refers to internal porosity (continuous and / or discontinuous) with an average pore diameter of 50 nm to 10,000 nm. “Microvoidic” refers to internal discrete voids with an average void diameter of 50 nm to 10,000 nm. The terms “microporous” and “microvoidic” are used interchangeably herein for the same purpose of reflecting solar energy and emitting far-infrared energy in atmospheric windows.

[0038] As used herein, the “atmospheric window” or “atmospheric window wavelength range” of the electromagnetic spectrum refers to a portion of the electromagnetic spectrum that partially or completely includes wavelengths that can be partially transmitted through the atmosphere. This atmospheric window may include at least some infrared wavelengths of light. The atmospheric window may be defined as being in the range of 8 to 13 micrometers, 7 to 14 micrometers, or even 6 to 14 micrometers.

[0039] As used herein, unless otherwise specified, “infrared” (IR) refers to infrared electromagnetic radiation with wavelengths from >700 nm to 1 mm.

[0040] As used herein, unless otherwise specified, “visible” (VIS) means visible electromagnetic radiation with wavelengths from 400 nm to 700 nm, including the end values.

[0041] As used herein, unless otherwise specified, “ultraviolet” (UV) means ultraviolet electromagnetic radiation with a wavelength of at least 250 nm and at most 400 nm but not including 400 nm.

[0042] As used herein, unless otherwise specified, “radiation” refers to electromagnetic radiation.

[0043] As used in this article, “absorption” refers to materials that convert light radiation energy into internal energy.

[0044] As used in this article, “absorption” relative to the wavelength of light includes both absorption and scattering, since scattered light will eventually be absorbed as well.

[0045] As used in this article, “scattering” relative to the wavelength of light refers to causing light to deviate from a straight path and travel in different directions with different intensities.

[0046] As used herein, "reflectivity" is a measure of the proportion of light or other radiation incident on a surface at a perpendicular angle of incidence and reflected by it. Reflectivity typically varies with wavelength and is reported as the percentage of incident light reflected from the surface (0% - no reflection, 100 - all light is reflected). Reflectivity and reflectance are used interchangeably herein.

[0047] As used in this article, “reflection” and “reflectivity” refer to the properties of reflected light or radiation, especially reflectivity measured independently of material thickness.

[0048] As used in this article, “average reflectance” refers to the average reflectance over a specified wavelength range.

[0049] Absorbance can be determined 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 measuring transmittance as previously described, and then calculating absorbance using Equation 1.

[0050] As used herein, the term "absorbance" in relation to quantitative measurement refers to the logarithm to base 10 of the ratio of incident radiant power to transmitted radiant power through the material. This ratio can be described as the radiant flux received by the material divided by the radiant flux transmitted through the material. Absorbance (A) can be calculated based on transmittance (T) according to the following formula 1:

[0051] A = -log 10 T (1)

[0052] Emissivity can be measured using an infrared imaging radiometer according to the method described in ASTM E1933-14 (2018), "Standard Practice for Measuring and Compensating for Emissivity Using Infrared Imaging Radiometers." Absorbance is related to emissivity according to Kirchhoff's laws of thermal radiation. Absorbance, absorbance, emissivity, and emittance are used interchangeably herein for the same purpose of emitting infrared energy into the atmosphere. Absorption and emission are also used interchangeably herein.

[0053] As used herein, the terms “transmittance” and “transmittance” refer to the ratio of the total transmittance of a material layer to the total transmittance received by the material, which can account for the effects of absorption, scattering, reflection, etc. Transmittance (T) can be expressed in the range of 0 to 1 or as a percentage (T%).

[0054] As used herein, “transparent” means a material (e.g., a film or layer) that absorbs less than 20% of light with wavelengths between 350 nm and 2500 nm.

[0055] As used in this article, “bandwidth” refers to the width of a continuous wavelength band.

[0056] As used in this article, “non-white” refers to a material that absorbs a predetermined wavelength band, peak, or spectrum in the visible spectrum that is associated with a predetermined color other than white.

[0057] As used in this article, "white" refers to a material that scatters light in the visible spectrum, giving it a white appearance.

[0058] As used herein, the term "passive radiative cooling" refers to providing cooling without consuming energy from an energy source, such as a battery or other power source. Passive radiative cooling can be defined as the opposite of "active cooling," which consumes an energy source (e.g., cooling via an air conditioning unit with an electrically driven compressor and fan).

[0059] As used in this article, the term "sub-ambient cooling" refers to cooling a surface to below ambient air temperature.

[0060] Radiant cooling products

[0061] In a first aspect, this disclosure provides a radiation cooling article. The radiation cooling article comprises:

[0062] a) A white diffuse reflective microporous layer having a solar-weighted reflectivity of 0.8 or greater, 0.85, 0.9 or 0.95 or greater, for most vertically incident electromagnetic radiation in the wavelength range of 350 nm to 2500 nm; and

[0063] b) A non-white colored reflective film having multiple first optical layers and multiple second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse reflective microporous layer, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm. The non-white colored reflective film has a higher reflectivity than the white diffuse reflective microporous layer.

[0064] See Figure 1 The schematic cross-sectional view of this disclosure shows that a colored radiation-cooled article 100 is provided by combining a non-white colored reflective film 120 with a white diffuse-reflective radiation-cooling film 110. Suitable reflective films can be tuned to reflect, for example, blue, green, or red light, and have a higher reflectivity than a white diffuse-reflective film reflecting the same wavelength. In at least some embodiments, the unique combination of the non-white colored reflective film and the white diffuse-reflective microporous layer produces a colored film capable of reflecting more than 80% of solar energy, a requirement for surface sub-environmental cooling. These unique combinations also tend to have an emissivity in the atmospheric window range of 8 to 13 micrometers, another requirement for surface sub-environmental cooling. Colored radiation-cooling films may be particularly useful for commercial graphic applications on vehicles including buses, trucks, trains, and even automobiles.

[0065] In some embodiments, the radiation-cooled article includes one or more markings on the main surface of at least one of a white diffuse-reflective microporous layer or a non-white colored reflective film. For aesthetic and marketing reasons, colored mirrors can be used to create colored patterns to form graphics including the markings. Furthermore, one or more infrared-reflective colored pigments can be printed into graphic patterns including letters and numbers on the white diffuse-reflective microporous layer or the colored reflective film. For example, Embodiment 3 of this disclosure provides a red "3M" logo, which is achieved by printing black ink on a white diffuse-reflective microporous layer and laminating it onto a red reflective film. The 3M logo appears red because only the light reflected by the red mirror is visible against a black background. Figure 18 A black and white photograph of this embodiment is provided.

[0066] Any infrared-reflective ink or pigment is suitable for the articles of manufacture disclosed herein. For example, some suitable materials include the paints described in PCT Publication WO 2020 / 072818 (Ruan et al.), which is incorporated herein by reference in its entirety, comprising particle-polymer composites containing nanoparticles or microparticles in a polymer matrix. Preferably, the particles have an electronic band gap greater than 3.2 eV. The particles may be formed from CaCO3, BaSO4, ZnS, SiO2, Al2O3, MgO, YAlO3, CaO, MgAl2O4, and / or LaAlO3, and optionally present in the paint in an amount greater than 10% by volume. The polymer matrix may be formed from acrylic acid, silicone, polyvinyl alcohol, or polydimethylsiloxane.

[0067] In some embodiments, the infrared reflective pigment may be an inorganic oxide pigment. Exemplary infrared reflective pigments may include, but are not limited to, the following: titanium dioxide, zinc sulfide, titanium brown ridge, chromium oxide green, iron oxide red, chromium titanate yellow, and nickel titanate yellow. Infrared reflective pigments may include metals and metal alloys of aluminum, chromium, cobalt, iron, copper, manganese, nickel, silver, gold, iron, tin, zinc, bronze, and brass. Metal alloys may include zinc-copper alloys, zinc-tin alloys, and zinc-aluminum alloys, etc. Some specific embodiments include nickel-antimony titanium, nickel-niobium titanium, chromium-antimony titanium, chromium-niobium, chromium-tungsten titanium, chromium-iron-nickel, chromium-iron oxide, chromium oxide, chromium titanate, manganese-antimony titanium, manganese ferrite, chromium green black, cobalt titanate, chromite or phosphate, cobalt magnesium and aluminate, iron oxide, iron-cobalt ferrite, iron-titanium, zinc ferrite, zinc-iron chromite, copper chromite, or combinations thereof. Commercially available inorganic infrared reflective pigments, including those sold under the trade names XFAST, SICOPAL, METEOR, and SICOTAN, are available from BASF Corporation (Southfield, MI). For example, XFAST Black 0095 has less absorption than conventional black pigments. Other inorganic infrared reflective pigments are available from Shepherd Color Company in Cincinnati, Ohio, and Ferro in Cleveland, Ohio.

[0068] Infrared reflective pigments can be homogeneous or heterogeneous. For example, an infrared reflective pigment can be a composite material comprising a coating on a core material, such as a silica core coated with a metal (such as copper), or mica particles coated with titanium dioxide. Exemplary composite pigments comprising coloring pigments adsorbed on the surface of metal particles are described in U.S. Patent No. 5,037,475 (Chida et al.), which is incorporated herein by reference. Such non-ferrous metallic pigments are commercially available from USAl, Inc., Flemington, NJ under the trade name FIREFLAKE.

[0069] Surprisingly, articles according to this disclosure have been found to exhibit passive radiative cooling properties. This is surprising, at least because colored articles typically have lower cooling capacity, particularly compared to colorless articles. In some embodiments, the radiatively cooled articles according to this disclosure have an average electromagnetic radiation absorbance of at least 0.80 in the wavelength range of 8 to 13 micrometers, such as 0.81 or greater, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, or 0.90 or greater. It should be understood that the percentage of incident light absorbed refers to the amount of light absorbed over a specific wavelength range (as opposed to the amount of light absorbed at a single wavelength). Preferably, the radiatively cooled articles according to at least some embodiments of this disclosure exhibit passive radiative cooling to below ambient temperature under direct sunlight.

[0070] The following will describe in detail each of the white diffuse microporous layer and the non-white colored mirror film:

[0071] White diffuse reflective microporous layer

[0072] The white diffuse-reflective microporous layer may comprise a network of interconnected and / or discrete voids, which may be spherical, oval, or some other shape. The primary functions of the white diffuse-reflective microporous layer include reflecting at least a portion of the visible and infrared radiation of the solar spectrum, and emitting thermal radiation within an atmospheric window (i.e., wavelengths from 8 to 14 micrometers).

[0073] Therefore, the white diffuse-reflective microporous layer has voids with appropriate sizes that allow it to diffusely reflect wavelengths in the 350 nm to 2500 nm wavelength range. Generally, this means that the void size should be within a certain range (e.g., 100 nm to 3000 nm). Preferably, there exists a void size range corresponding to those sizes to achieve effective broadband reflection. As used herein, the term "polymer" includes synthetic and natural organic polymers (e.g., cellulose and its derivatives). In some embodiments, the white diffuse-reflective microporous layer comprises a polyester or a polyester copolymer. In some embodiments, the white diffuse-reflective microporous layer comprises at least one of polyethylene, polypropylene, polysaccharides, fluoropolymers, or fluoropolymer copolymers. Typically, the white diffuse-reflective microporous layer comprises a microporous membrane.

[0074] The reflectivity of a white diffuse-reflective microporous layer typically depends on the number of polymer film / void interfaces, as reflection (usually diffuse reflection) occurs at those locations. Therefore, the porosity and thickness of the white diffuse-reflective microporous layer are important variables. Generally, higher porosity and higher thickness are associated with higher reflectivity. However, for cost reasons, film thickness is preferably minimized, but this is not mandatory. Therefore, the thickness of the white diffuse-reflective microporous layer is typically in the range of 10 micrometers to 500 micrometers, preferably in the range of 10 micrometers to 200 micrometers, but this is not mandatory. Similarly, the porosity of the white diffuse-reflective microporous layer is typically in the range of 10 vol% to 90 vol%, preferably in the range of 20 vol% to 85 vol%, but this is not mandatory.

[0075] Microporous polymer membranes suitable for use as white diffuse reflective microporous layers are known in the art and described, for example, in U.S. Patent No. 8,962,214 (Smith et al.) entitled "Microporous PVDF Films", U.S. Patent No. 10,240,013 (Mrozinski et al.) entitled "Microporous Material from Ethylene-Chlorotrifluoroethylene Copolymer and Method for Making Same", and U.S. Patent No. 4,874,567 (Lopatin et al.) entitled "Microporous Membranes from Polypropylene". These membranes may have an average pore size of at least 0.05 micrometers.

[0076] In some embodiments, the white diffuse-reflective microporous layer comprises at least one thermally induced phase separation (TIPS) material. Due to the ability to selectively stretch the layer, the pore size of the TIPS material can generally be controlled. The preparation of TIPS materials is relatively inexpensive, and methods for preparing this membrane are known to those skilled in the art. For example, various materials and methods are described in detail in U.S. Patent Nos. 4,726,989 (Mrozinski), 5,238,623 (Mrozinski), 5,993,954 (Radovanovic et al.), and 6,632,850 (Hughes et al.). The white diffuse-reflective microporous layer used in aspects of this disclosure also includes solvent-induced phase separation (SIPS) materials (e.g., U.S. Patent No. 4,976,859 (Wechs)) and other white diffuse-reflective microporous layers prepared by extrusion processes, extrusion / stretching processes, and extrusion / stretching / extraction processes. Suitable white diffuse-reflective microporous layers that can be formed from SIPS include, for example, but not limited to, the following: polyvinylidene fluoride (PVDF), polyethersulfone (PES), polysulfone (PS), polyacrylonitrile (PAN), nylon (i.e., polyamide), cellulose acetate, nitrocellulose, regenerated cellulose, and polyimide. Suitable white diffuse-reflective microporous layers that can be formed by stretching techniques (e.g., U.S. Patent No. 6,368,742 (Fisher et al.)) include, for example, but not limited to, polytetrafluoroethylene (PTFE) and polypropylene.

[0077] In some embodiments, the white diffuse reflective microporous layer comprises a thermoplastic polymer, such as polyethylene, polypropylene, 1-octene, styrene, polyolefin copolymer, polyamide, poly-1-butene, poly-4-methyl-1-pentene, polyethersulfone, ethylene tetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyacrylonitrile, polyamide, cellulose acetate, nitrocellulose, regenerated cellulose, polyvinyl chloride, polycarbonate, polyethylene terephthalate, polyimide, polytetrafluoroethylene, chlorotrifluoroethylene, or combinations thereof.

[0078] Materials suitable for use as white diffuse reflective microporous layers include nonwoven fiber layers. Polymer nonwoven layers can be produced using a meltblown process. Meltblown nonwoven fiber layers can contain ultrafine fibers. In meltblowing, one or more streams of thermoplastic polymer are extruded through a die containing a densely arranged array of orifices. These polymer streams are refined by a converging flow of high-speed hot air to form fine denier fibers, which are then collected on a surface to provide a meltblown nonwoven fiber layer. Depending on the selected operating parameters, the collected fibers can be semi-continuous or substantially discontinuous. Polymer nonwoven layers can also be prepared by a process known as melt spinning. In melt spinning, nonwoven fibers are extruded as filaments outside a set of orifices and allowed to cool and solidify to form fibers. The filaments pass through an air space that can accommodate a flow of moving air to aid in cooling the filaments and through a drawing (i.e., stretching) unit to at least partially lengthen the filaments. Fibers produced by melt spinning can be "spunbonded," whereby a web comprising a set of melt-spun fibers is collected as a fiber web and optionally subjected to one or more bonding operations to fuse the fibers together. The diameter of melt-spun fibers is generally larger than that of melt-blown fibers.

[0079] Polymers suitable for meltblown or melt spinning processes include polyolefins such as polypropylene and polyethylene, polyesters, polyethylene terephthalate, polybutylene terephthalate, polyamides, polyurethanes, polybutene, polylactic acid, polyphenylene sulfide, polysulfones, liquid crystal polymers, ethylene-vinyl acetate copolymers, polyacrylonitrile, cyclic polyolefins, and copolymers and blends thereof. In some embodiments, the polymer, copolymer, or blend thereof constitutes at least 35% of the total weight of the directly formed fibers present in the nonwoven fiber layer.

[0080] Nonwoven fibers can be made from thermoplastic semi-crystalline polymers, such as semi-crystalline polyesters. Available polyesters include aliphatic polyesters. Nonwoven materials based on aliphatic polyester fibers are particularly advantageous in high-temperature applications due to their resistance to degradation or shrinkage. This property can be achieved by preparing nonwoven fiber layers using a meltblown process, wherein the meltblown fibers undergo a controlled air heat treatment operation immediately upon exiting from multiple orifices. The controlled air heat treatment operation is carried out at a temperature below the melting temperature of a portion of the meltblown fiber and lasts for a time sufficient to allow at least a portion of the molecules within the portion of the fiber undergoing the controlled air heat treatment operation to achieve stress relaxation. Details of the air heat treatment are described in U.S. Patent Application Publication No. 2016 / 0298266 (Zillig et al.).

[0081] Nonwoven fiber layers that can be used for white diffuse reflective microporous layers comprise nonwoven fiber layers made using an air-blowing process, wherein air walls blow fibers onto a perforated collection cylinder with negative pressure inside. Air is drawn through the cylinder, collecting the fibers on the outside, where they are removed as fiber webs.

[0082] An exemplary embodiment of a microporous membrane made of nonwoven fibers is a high-reflectivity white paper containing polysaccharides. Microporous polysaccharide white paper with a reflectivity greater than 90% for visible wavelengths from 400 nm to 700 nm is available under the trade names IP ACCENTOPAQUE DIGITAL (100 lbs), IP ACCENT OPAQUE DIGITAL (100 lbs), HAMMERMILL PREMIUM COLOR COPY (80 lbs), and HAMMERMILL PREMIUM COLOR COPY (100 lbs) from International Paper, Memphis, Tennessee. Titanium dioxide, BaSO4, and other white pigments are typically added to the paper to increase its reflectivity to visible light (400 nm to 700 nm).

[0083] Other nonwoven fiber layers that can be used for white diffuse reflective microporous layers include those prepared using a wet web-forming process. A wet web-forming or “wet web-type” process includes: (a) forming a dispersion in at least one dispersion liquid (preferably water) comprising one or more types of fibers, optional polymer binders, and optional particulate fillers; and (b) removing the dispersion liquid from the dispersion.

[0084] Fibers suitable for air-laid and wet-laid processes include those made from natural polymers (animal or plant) and / or synthetic polymers (including thermoplastic polymers and solvent-dispersible polymers). Available polymers include wool; silk; cellulose polymers (e.g., cellulose and cellulose derivatives); fluorinated polymers (e.g., copolymers of polyvinylidene fluoride, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene)), and trifluorochloroethylene copolymers (e.g., poly(ethylene-co-trifluorochloroethylene)); chlorinated polymers; polyolefins (e.g., copolymers of polyethylene, polypropylene, poly-1-butene, ethylene and / or propylene with 1-butene, 1-hexene, 1-octene, and / or 1-decene (e.g., poly(ethylene-co-1-butene), poly(ethylene-co-1-butene-co-1-hexene)); polyisoprene; polybutadiene; polyamides (e.g., nylon 6, nylon 6,6, nylon 6...). 12. Poly(iminohexamethylene adipamide), poly(iminohexamethylene adipamide), or polycaprolactam; polyimide (e.g., poly(pyromellitic terephthalamide)); polyether; polyethersulfone (e.g., poly(diphenyl ether sulfone) or poly(diphenyl sulfone-co-diphenyl ether sulfone)); polysulfone; polyvinyl acetate; copolymers of vinyl acetate (e.g., poly(ethylene-co-vinyl acetate), wherein at least some of the acetate groups have been hydrolyzed to provide a variety of poly(vinyl alcohol) (including poly(ethylene-co-vinyl alcohol)); polyphosphazene; polyvinyl ester; polyvinyl ether; poly(vinyl alcohol); polyaromatic amide (e.g., poly-p-aromatic amide, such as poly(p-phenylene terephthalamide) and DuPont of Wimington, Delaware). Co., Wilmington, DE sells fibers under the trade name KEVLAR, whose slurries are commercially available in a variety of grades based on the fiber length from which the slurry is made, such as KEVLAR 1F306 and KEVLAR 1F694, both of which contain polyaramid fibers with a length of at least 4 mm; polycarbonate; and combinations thereof. The nonwoven fiber layers may be calendered to adjust the pore size.

[0085] Using a reflective microporous polymer film as a white diffuse reflective microporous layer can provide even greater reflectivity than a silvered mirror. In some embodiments, the reflective microporous polymer film reflects the maximum amount of solar energy in the range of 350 nanometers (nm) to 2500 nanometers. Specifically, using a fluoropolymer blend in this microporous polymer film can provide greater reflectivity than other conventional multilayer optical films. Furthermore, inorganic particles including barium sulfate, calcium carbonate, silica, alumina, aluminum silicate, zirconium oxide, and titanium dioxide can be blended into the microporous polymer film to provide high solar reflectivity in the 0.4-micrometer to 2.5-micrometer solar radiation spectrum and high absorbance in the 8-micrometer to 13-micrometer atmospheric window. Preferably, the inorganic particles are white inorganic particles. In some embodiments, the article can form part of a cooling panel that can be disposed on the exterior of at least a portion of a building or heat transfer system. This heat transfer system can cool a fluid, liquid, or gas that can then be used to remove heat from a building or vehicle (including electric vehicle batteries). The outer layer can be used to protect the white diffuse reflective microporous layer, especially in outdoor environments. Including the outer layer also helps reduce surface dirt and makes the surface easier to clean.

[0086] Exemplary polymers that can be used to form reflective microporous polymer films include polyethylene terephthalate (PET), available from 3M. Modified PET copolyesters are also available high-refractive-index polymers, including PETG, such as SPECTAR 14471 and EASTAR GN071, available from Eastman Chemical Company, Kingsport, TN, Tennessee, and PCTG, such as TIGLAZE ST and EB0062, also available from Eastman Chemical Company. Stretching can increase the molecular orientation of PET and PET-modified copolyesters, which increases the in-plane refractive index of PET and PET, thereby providing even higher reflectivity in multilayer optical films. Generally, prior to stretching, incompatible polymeric additives or inorganic particulate additives are blended into the PET bulk polymer during extrusion at a content of at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt%, or even at least 49 wt% to nucleate voids during stretching. Incompatible polymer additives suitable for PET include fluoropolymers, polypropylene, polyethylene, and other polymers that do not adhere well to PET. Similarly, if polypropylene is the host polymer, incompatible polymer additives such as PET or fluoropolymers can be added to the polypropylene host polymer during extrusion at a content of at least 1% by weight, at least 5% by weight, at least 10% by weight, at least 20% by weight, at least 30% by weight, at least 40% by weight, or even at least 49% by weight to nucleate voids during the stretching process. Exemplary suitable inorganic particulate additives for nucleating voids in microporous polymer films include titanium dioxide, silica, alumina, aluminum silicate, zirconium oxide, calcium carbonate, barium sulfate, and glass beads and hollow glass bulbs, but other inorganic particles and combinations of inorganic particles can also be used. Crosslinked polymer microspheres can also be used instead of inorganic particles. Preferably, the polymer particles comprise aromatic polyester particles. Prior to stretching, inorganic particles may be added to the host polymer during extrusion at a content of at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt%, or even at least 49 wt% to nucleate voids during stretching. If present, the inorganic particles preferably have a volume average particle size of 5 nm to 1 micrometer, but other particle sizes may also be used. Hard particles, including glass beads and / or glass bubbles, may be present on the surface layer of the UV reflector or antifouling layer to provide scratch resistance. In some embodiments, the glass beads and / or glass bubbles may even protrude from the surface as hemispheres or even quarter-spheres.Crosslinked polymer beads (such as those available under the trade name "CHEMISNOW" from Soken Chemical and Engineering Co., Ltd., Japan) can be effective void nucleating agents. Glass beads (such as those available under the trade name "SPHERIGLASS" from Potters Industries LLC) can be effective nucleating agents. Similarly, if polypropylene is the base polymer, incompatible polymer additives such as PET or fluoropolymers, or crosslinked polymer beads or glass beads, can be added to the polypropylene base polymer during extrusion at a content of at least 1% by weight, at least 5% by weight, at least 10% by weight, at least 20% by weight, at least 30% by weight, at least 40% by weight, or even at least 49% by weight to induce void nucleation during the stretching process.

[0087] In some embodiments, the microporous polymer membrane comprises a fluoropolymer continuous phase. Exemplary suitable polymers include ECTFE, PVDF, and copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, such as those available, for example, under the trade name THV, from 3M Company. The use of a fluoropolymer continuous phase may be advantageous when the radiation-cooled article is formed to be at least partially non-planar, as fluoropolymers are generally more flexible than other polymers, such as PET.

[0088] Exemplary microporous PET films containing barium sulfate, such as LUMIRROR XJSA2, are available from Toray Plastics (America) Inc., North Kingstown, RI, Rhode Island. LUMIRROR XJSA2 includes CaCO3 inorganic additives and cross-linked polymer beads to increase its reflectivity for visible light (400 nm to 700 nm) and solar energy (350 nm to 2500 nm). Other exemplary reflective microporous polymer films, such as HOSTAPHAN V54B, HOSTAPHAN WDI3, and HOSTAPHAN W270, are available from Mitsubishi Polymer Film, Inc., Greer, SC, South Carolina.

[0089] Exemplary microporous polyolefin membranes are described, for example, in U.S. Patent No. 6,261,994 (Bourdelais et al.).

[0090] The white diffuse reflective microporous layer is diffusely reflective to visible light radiation, for example, in the range of wavelengths from 350 nm to 700 nm, including the end values. In some embodiments, the white diffuse reflective microporous layer may have an average reflectivity of at least 85% (in some embodiments, 375 nm or greater, 400 nm, 425 nm, 450 nm, 475 nm, 500 nm, 525 nm, 550 nm, 575 nm, or 600 nm or greater) to at most 700 nm (in some embodiments, 675 nm or less, 650 nm, 625 nm, 600 nm, 575 nm, 550 nm, 525 nm, or 500 nm or less) in a wavelength range of at least 350 nm (in some embodiments, 675 nm or less, 650 nm, 625 nm, 600 nm, 575 nm, 550 nm, 525 nm, or 500 nm or less) (in some embodiments, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or even at least 99.5%).

[0091] The reflectivity of the white diffuse-reflective microporous layer can be reflective over a wide wavelength range. Therefore, in some embodiments, the microporous polymer layer may have an average reflectivity of at least 85% (in some embodiments, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or even at least 99.5%) over a wavelength range of at least 400 nm to at most 2.5 μm, preferably at least 300 nm to 3.0 μm, but this is not required.

[0092] Non-white colored reflective film

[0093] The use of multilayer reflective films comprising alternating layers of two or more polymers to reflect light is known and described, for example, in U.S. Patent Nos. 3,711,176 (Alfrey, Jr. et al.), 5,103,337 (Schrenk et al.), WO 96 / 19347 (Jonza et al.), and WO 95 / 17303 (Ouderkirk et al.). The reflection and transmission spectra of a particular multilayer film depend primarily on the optical thickness of each layer, which is defined as the product of the actual thickness of the layer and its refractive index. Therefore, by selecting appropriate layer optical thicknesses according to the following formula, the film can be designed to reflect infrared, visible, or ultraviolet wavelengths λ. M Light:

[0094] λ M = (2 / M)*D r

[0095] Where M is an integer representing a specific order of the reflected light, and D rIt is the optical thickness of an optical repeating unit comprising two or more polymer layers (also known as a multilayer stack). Therefore, D r It is the sum of the optical thicknesses of the individual polymer layers that constitute the optical repeating unit. D r The thickness is always half of λ(λ), where λ is the wavelength of the first-order reflection peak. Multilayer films that reflect light within a broadband wavelength range can be designed by varying the optical thickness of the optical repeating unit along the thickness of the multilayer film. This band is commonly referred to as the reflection band or stop band. In some embodiments, the reflection band has sharp spectral edges on the long wavelength (red) side and / or the short wavelength (blue) side. It may be desirable to design a reflective film or other optical body that reflects light within a selected range of the visible light region of the spectrum, such as a reflective film that reflects only green light. In this case, it may be desirable to have sharp edges on both the red and blue sides of the reflection band. For example, a multilayer optical film with sharp reflection band edges is described in detail in U.S. Patent No. 6,967,778 (Wheatley et al.), which is incorporated herein by reference in its entirety.

[0096] In one embodiment, an optical polymer film or a layered optical polymer film having a first main surface and a second main surface is provided. The term "film" is used to refer to a planar form of plastic with a thickness sufficient for self-support, but also sufficient to bend, fold, laminate, or wrinkle without cracking. The film thickness depends on the desired application and manufacturing method.

[0097] As used herein, "optical film" refers to any reflective or partially reflective polymer film designed to exhibit desired light reflection, transmission, absorption, or refraction when exposed to electromagnetic energy of a specific wavelength band. Therefore, conventional, typically transparent polymer films, such as polyester and polypropylene, should not be considered "optical films" for the purposes of this disclosure, even though they may exhibit some degree of reflection or glare when viewed from certain angles. However, films exhibiting both reflective and transmissive properties (such as those that are partially transmissive) are considered to be included within the scope of this disclosure. Preferred optical polymer films typically absorb less than 25% of the radiant energy impacting their surface. However, if the optical polymer film is colored by introducing a colorant into the film, the colorant material may absorb more radiant energy. Preferably, the absorbed radiant energy is less than 10%, and most preferably less than 5%. Radiant energy, typically expressed as energy within a certain wavelength range, can be specularly or diffusely reflected. This reflection can be isotropic, meaning the film has the same reflective properties along both in-plane axes; or it can be anisotropic, meaning the film has different reflective properties along a perpendicular in-plane axis. By controlling the relationship between the refractive indices of each constituent material along each axis, the difference in reflection properties along the in-plane axis can be varied.

[0098] Optical films come in various forms and are selected based on the desired application. Some suitable embodiments include multilayer polarizers, visible and infrared mirrors, and colored films, such as those published in patents WO 95 / 17303, WO 96 / 19347, and WO 97 / 01440; U.S. Patent Nos. 6,045,894 (Jonza et al.), 6,531,230 (Weber et al.), 5,103,337 (Schrenk et al.), 5,122,905 (Wheatley et al.), 5,122,906 (Wheatley), 5,126,880 (Wheatley et al.), 5,217,794 (Schrenk), 5,233,465 (Schrenk et al.), and 5,262,894 (Wheatley et al.). The entire contents of U.S. Patent No. 5,278,694 (Wheatley et al.), U.S. Patent No. 5,339,198 (Wheatley et al.), U.S. Patent No. 5,360,659 (Arends et al.), U.S. Patent No. 5,448,404 (Schrenk et al.), U.S. Patent No. 5,486,949 (Schrenk et al.), U.S. Patent No. 4,162,343 (Wilcox et al.), U.S. Patent No. 5,089,318 (Shetty et al.), U.S. Patent No. 5,154,765 (Armanini), and U.S. Patent No. 3,711,176 (Alfrey, Jr. et al.), as well as the reprinted U.S. Patent No. RE 31,780 (Cooper et al.) and U.S. Patent No. RE 34,605 ​​(Schrenk et al.) are incorporated herein by reference.

[0099] In some embodiments, non-white colored mirrors are designed as dichroic mirrors, i.e., mirrors with high reflectivity (and low transmittance) for some wavelengths of light and low reflectivity (and high transmittance) for others. Such mirrors typically have negligible absorption, at least for visible and near-infrared wavelengths, such that any light not reflected is essentially transmitted. These reflectors comprise stacks of thin optical layers (typically alternating layers of materials with a large refractive index mismatch, such as alternating layers of silica and titanium dioxide), but other suitable inorganic or organic materials may also be used. Such mirrors can be fabricated by vacuum depositing alternating layers onto glass or other suitable substrates. Alternatively, suitable mirror films can be manufactured via a continuous process involving co-extruding alternating polymer materials and stretching the resulting multilayer polymer webs, for example, as described in U.S. Patent Nos. 5,882,774 (Jonza et al.) and 6,783,349 (Neavin et al.). Regardless of the materials used in each (e.g., dichroic) mirror and the manufacturing method employed, the mirror is provided with a layer thickness profile for the microlayer stack, which is tailored to provide desired reflective characteristics as a function of wavelength. For this purpose, reference can be made to U.S. Patent 6,967,778 (Wheatley et al.). The thickness profile can be customized as needed to provide a dichroic mirror for use as, for example, a long-pass filter, a short-pass filter, or a notch filter.

[0100] Examples of optical films comprising immiscible blends of two or more polymeric materials include blend constructions in which reflective and transmittance properties are derived from the presence of discontinuous polymeric regions having cross-sectional diameters perpendicular to the principal axis, on the order of a fraction of the distance corresponding to the wavelength of light, and which can also be oriented to obtain desired optical properties, such as blended objectives and polarizers described in Patent Publication WO 97 / 32224 (Ouderkirk et al.), U.S. Patent No. 6,179,948 (Merrill et al.), and U.S. Patent No. 5,751,388 (Larson), the entire contents of which are incorporated herein by reference. Suitable additional reflective films include reflective cubic corner sheets described in U.S. Patent No. 5,450,235 (Smith et al.), U.S. Patent No. 5,691,846 (Benson et al.), U.S. Patent No. 5,614,286 (Bacon et al.), and U.S. Patent No. 5,763,049 (Frey et al.), all descriptions of which are incorporated herein by reference. Examples of these films are commercially available, such as 3M SCOTCHLITE Reflective Material Series 6200 High Gloss Film and SCOTCHLITE Diamond Grade Ultra-Flexible High-Gloss Sheet Series 960 from 3M. These optical films achieve their optical properties through a cured solid angle structure on one side of the polymer film structure.

[0101] In some embodiments, the non-white colored reflective film comprises a multilayer optical film comprising alternating layers of polyethylene terephthalate (PET) and methyl methacrylate copolymer (coPMMA). In some embodiments, the non-white colored reflective film comprises a multilayer optical film comprising alternating layers of PET and fluoropolymers.

[0102] Advantageously, non-white colored reflective film can provide reflected color by reflecting a wavelength bandwidth of at least 30 nm (in some embodiments, 32 nm or greater, 35 nm, 37 nm, 40 nm, 42 nm, 45 nm, 45 nm, 40 nm, 400 nm, 500 nm, 55 nm, 57 nm, 60 nm, 62 nm, 65 nm, 67 nm, 70 nm, 72 nm, or 75 nm or greater) in the wavelength range of 380 nm to 450 nm (e.g., reflected purple), 450 nm to 500 nm or 400 nm to 500 nm (e.g., reflected blue), 500 nm to 600 nm (e.g., reflected green), or 600 nm to 700 nm (e.g., reflected red). In some embodiments, the non-white colored mirror also reflects a wavelength bandwidth of at least 30 nm (in some embodiments, at least 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm) in the wavelength range of 700 nm to 2000 nm (such as 700 nm or greater, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm, or 1300 nm or greater; and 2000 nm or less, 1950 nm, 1900 nm, 1850 nm, 1800 nm, 1750 nm, 1700 nm, 1650 nm, 1600 nm, 1550 nm, 1500 nm, 1450 nm, 1400 nm, or 1350 nm or less).

[0103] See now Figure 12AIn use, the radiative cooling article 1200 can be fixed to the substrate 1210, so that the radiative cooling article 1200 and the substrate 1210 are in thermal communication and together form a composite cooling system 1250. The radiative cooling article 1200 can be generally planar; however, it does not need to be planar and can be flexible to conform to the substrate 1210. The composite cooling system 1250 can reflect sunlight 1204 to cool the substrate 1210, which can be particularly effective in daytime environments. In the absence of the radiative cooling article 1200, sunlight 1204 can be absorbed by the substrate 1210 and converted into heat. The reflected sunlight 1205 can be guided into the atmosphere 1208. The radiative cooling article 1200 can radiate light 1206 in the atmospheric window region of the electromagnetic spectrum into the atmosphere 1208 to cool the substrate 1210, which can be particularly effective in nighttime environments. The radiative cooling article 1200 allows heat to be converted into light 1206 (e.g., infrared light) that can escape through an atmospheric window 1208 from the atmosphere. The radiation of light 1206 can be a characteristic of the radiative cooling article 1200 that requires no additional energy and can be described as passive radiation that cools the radiative cooling article 1200 and its thermally coupled substrate 1210. During the day, reflective properties allow the radiative cooling article 1200 to emit more energy than it absorbs. By combining radiative and reflective properties to reflect sunlight during the day, the radiative cooling article 1200 can provide more cooling than an article that merely radiates energy through the atmosphere and into space.

[0104] The radiative cooling product 1200 is suitable for outdoor environments and possesses, for example, a suitable operating temperature range, water resistance, and ultraviolet (UV) stability. Resistance to photo-oxidation can be measured by changes in reflectance or color. The passive radiative cooling product described herein does not exhibit a reflectance change greater than 5% over at least 5 years. The passive radiative cooling product described herein withstands exposure to 18,700 kJ / m² at 340 nm. 2 The color change should not exceed 5 (as described in ASTM G-155-13 (2013) as b*). One mechanism for detecting changes in physical properties is weathering cycling using a D65 light source in reflective mode, as described in ASTM G155-05a (October 2005). According to the aforementioned test, the article should be able to withstand at least 18,700 kJ / m at 340 nm. 2 Exposure will not change reflectivity, color, cracking, or surface pitting.

[0105] Exemplary substrates for substrate 1210 include vehicles (e.g., roofs, body panels, and / or windows), buildings (e.g., roofs, walls), heat exchangers, clothing, umbrellas, hats, boats, and trams. Exemplary substrates may be part of a larger article of manufacture, device, or system (e.g., a window of a building).

[0106] In a second aspect, this disclosure provides a composite cooling system. The composite cooling system includes radiant cooling articles attached to a vehicle or trailer. For example, see... Figure 12B In use, one or more radiative cooling articles 1200 can be fixed to a base 1210 of a vehicle (or trailer, not shown), such that the one or more radiative cooling articles 1200 are in thermal communication with the base 1210 and together form a composite cooling system 1250. The radiative cooling article 1200 may be generally planar; however, it does not need to be planar and may be flexible to conform to the base 1210. Radiative cooling can be used as described above regarding... Figure 12A The aforementioned composite cooling system 1250 is used to achieve this.

[0107] Among other parameters, the amount of cooling and the amount of temperature reduction may depend on the reflective and absorptive characteristics of the radiative cooling article 1200. The cooling effect of the radiative cooling article 1200 can be described with reference to a first temperature of ambient air near or adjacent to the substrate 1210 and a second temperature of a portion of the substrate 1210 near or adjacent to the radiative cooling article 1200. In some embodiments, the first temperature is at least 0.5 degrees Celsius (in some embodiments, at least 1, 1.5, 1.7, 2, 2.5, 2.7, 3, 3.5, 4, 4.5, 5, 5.5, 8.3, or even at least 11.1 degrees Celsius) higher than the second temperature (e.g., at least 0.9, 1.8, 3.6, 5, 10, 15, or even at least 20 degrees Fahrenheit) and 12 degrees Celsius or lower.

[0108] Optional Layer

[0109] See Figure 2 The diagram shows a schematic side view of an exemplary radiative cooling article 200. The radiative cooling article 200 includes (e.g., indirectly) a non-white colored reflective film 220 adjacent to a white diffuse radiative cooling film 210, wherein several optional layers are located between the non-white colored reflective film 220 and the white diffuse radiative cooling film 210 and on either side of the non-white colored reflective film 220 and the white diffuse radiative cooling film 210.

[0110] In some embodiments, the radiative cooling article 200 includes an optional layer 230, which may be a hard coating or film, a protective layer, an anti-fouling layer, an infrared reflective layer, or an ultraviolet reflective multilayer optical film. The infrared reflective layer has an average reflectivity of at least 50% in the wavelength range of 700 nm to 2000 nm. The ultraviolet reflective multilayer optical film has a reflectivity of at least 50% for (e.g., incident) ultraviolet radiation at most wavelengths in the range of at least 340 nm but less than 400 nm (e.g., more than half the wavelength). Layer 230 is positioned adjacent to the non-white colored reflective film 220 and opposite to the white diffuse reflective cooling film 210. When layer 230 is a hard coating or film, a protective layer, or an anti-fouling layer, layer 230 is typically the outer layer of the radiative cooling article 200. The outer layer is typically configured to protect the non-white colored reflective film 220 from degradation due to problems such as corrosion, weathering, dirt, and scratches.

[0111] In some embodiments, the radiative cooling article 200 includes an optional layer 240 as a protective layer. When layer 230 is present and is an infrared reflective layer or an ultraviolet reflective multilayer optical film, layer 240 is typically a protective layer comprising a fluoropolymer.

[0112] In some embodiments, the radiation-cooled article 200 includes an optional layer 250, which is an infrared reflective layer disposed between a white diffuse microporous layer and a non-white colored reflective film.

[0113] In some embodiments, the radiative cooling article 200 includes one or more optional transparent adhesive bonding layers 272, 274, 276 and / or 278 that can bond the individual layers together, such as Figure 2 As shown. For example, transparent adhesive bonding layers 276 and / or 278 may be disposed between the white diffuse microporous layer and the non-white colored reflective film. When layer 230 is present and is an infrared reflective layer or an ultraviolet reflective multilayer optical film, an optional transparent adhesive bonding layer 274 may be present between the non-white colored reflective film 220 and layer 230.

[0114] In some embodiments, the radiative cooling article 200 includes an optional layer 260, which is a degassing adhesive disposed adjacent to the white diffuse microporous layer 210 and opposite to the non-white colored reflective film 220. Additionally, optionally, a spacer (not shown) may be disposed directly adjacent to the degassing adhesive layer 260. Optional spacers used with the optional adhesive layer may include, for example, polyolefin films, fluoropolymer films, coated PET films, silicone films, or paper.

[0115] Each of the optional layers described above is described in detail below.

[0116] Hard coating or film layer

[0117] Radiation-cooled articles optionally include a hard coating or film layer disposed adjacent to the main surface of a non-white colored reflective film and opposite to a white diffuse microporous layer. The hard coating or film layer is an outer layer. The hard coating or film layer can be any polymeric material that provides the desired effects, such as UV absorption and / or weather protection.

[0118] This layer can be co-extruded, extruded, laminated, or otherwise adhered to a non-white colored reflective film. Typically, the hard coating or film layer should be as thin as possible to minimize adverse effects on the optical properties of the radiation-cooled article. If desired, the hard coating or film layer can be applied using conventional coating methods such as roll coating (e.g., gravure roll coating) or spray coating (e.g., electrostatic spraying). Preferably, the hard coating or film layer is crosslinked using techniques similar to those employed when using crosslinked organic base coatings. Flash evaporation, vapor deposition, and crosslinking of monomers or oligomers can be used to form the hard coating or film layer. Examples of monomers or oligomers used in such protective layers include volatile (meth)acrylates. Some suitable polymeric materials for hard coatings or film layers include, for example, but not limited to, crosslinked acrylate polymers, polyurethane polymers, or vinyl polymers. The hard coating or film layer may also contain adhesion promoters.

[0119] protective layer

[0120] In some embodiments, the radiative cooling article optionally further includes a protective layer comprising a fluoropolymer, which is positioned adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer. The protective layer is the outer layer. In some embodiments, the protective layer includes a surface structure. In some embodiments, the outer surface of the protective layer is patterned and / or textured, for example, including a light matte finish. In some embodiments, a textured surface is provided for aesthetic purposes; for example, texturing may be used to give the layer the appearance of a natural wood grain.

[0121] Any suitable fluoropolymer material can be used in the protective layer. Non-limiting examples of usable fluoropolymers include: polymers of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (e.g., available from 3M under the trade name "3MDYNEON THV"); polymers of TFE, HFP, vinylidene fluoride, and perfluoropropyl vinyl ether (PPVE) (e.g., available from 3M under the trade name "3M DYNEON THVP"); polyvinylidene fluoride (PVDF) (e.g., "3M DYNEON PVDF 6008" from 3M); ethylene-chlorotrifluoroethylene (ECTFE) polymers (e.g., available from Solvay Group in Brussels, Belgium under the trade name "HALAR 350LCECTFE"); and ethylene-tetrafluoroethylene (ETFE) (e.g., available from 3M DYNEON ETFE). The following are examples of fluoropolymers: 6235 (purchased from 3M); perfluoroalkoxyalkane (PFA) polymers; fluorinated ethylene propylene (FEP) polymers; polytetrafluoroethylene (PTFE); polymers of TFE, HFP, and ethylene (e.g., purchased from 3M under the trade name "3M DYNEON HTE1705"); or various combinations thereof. Generally, various combinations of fluoropolymers may be used. In some embodiments, the fluoropolymer includes FEP. In some embodiments, the fluoropolymer includes PFA.

[0122] Examples of suitable fluoropolymers include those available from companies such as 3M under the following trade names: “3M DYNEON THV221GZ” (39 mol% tetrafluoroethylene, 11 mol% hexafluoropropylene, and 50 mol% vinylidene fluoride), “3M DYNEON THV2030GZ” (46.5 mol% tetrafluoroethylene, 16.5 mol% hexafluoropropylene, 35.5 mol% vinylidene fluoride, and 1.5 mol% perfluoropropyl vinyl ether), “3M DYNEON THV610GZ” (61 mol% tetrafluoroethylene, 10.5 mol% hexafluoropropylene, and 28.5 mol% vinylidene fluoride), and “3M DYNEON THV815GZ” (72.5 mol% tetrafluoroethylene, 7 mol% hexafluoropropylene, 19 mol% vinylidene fluoride, and 1.5 mol% perfluoropropyl vinyl ether). Examples of fluoropolymers also include, for example, PVDF purchased from 3M Company under the trade names “3MDYNEON PVDF6008” and “3M DYNEON PVDF 11010”; FEP purchased from 3M Company under the trade name “3MDYNEON FLUOROPLASTIC FEP 6303Z”; ECTFE purchased from Solvay Group under the trade name “HALAR350LC ECTFE”; those obtained as copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, purchased 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”; and those obtained as copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, purchased under the trade names “DYNEON ET 6210A” and “DYNEON ET 6210A”. 6235” is a copolymer of ethylene and tetrafluoroethylene purchased from Danielon LLC, DuPont de Nemours and Co., Wilmington, DE under the trade name “TEFZEL ETFE”, and Asahi Glass Ltd. under the trade name “FLUON ETFE”.

[0123] Antifouling layer

[0124] In some embodiments, the radiative cooling article optionally also includes an antifouling layer disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer. The antifouling layer is an outer layer. The antifouling layer provides a degree of protection against the accumulation of dirt on the surface, which could potentially impair the function of the radiative cooling article (e.g., by absorbing solar radiation).

[0125] In some embodiments, the optional antifouling layer is a polymer film, preferably comprising one or more repellent polymers, such as, for example, fluoropolymers. Examples of comonomers used to prepare usable fluoropolymers include TFE, HFP, THV, and PPVE. Exemplary fluoropolymers used as antifouling layers include PVDF, ECTFE, ETFE, PFA, FEP, PTFE, HTE, and combinations thereof. In some embodiments, the fluoropolymer includes FEP. In some embodiments, the fluoropolymer includes PFA.

[0126] In some embodiments, the antifouling layer is applied as a coating to a non-white colored mirror. Many of the applied antifouling compositions are known in the art, including, for example, those described in the following patents: U.S. Patent Application Publication 2015 / 0175479 (Brown et al.), 2005 / 0233070 (Pellerite et al.), U.S. Patent No. 6,277,485 (Invie et al.), and WO 02 / 12404 (Liu et al.).

[0127] In some embodiments, the optional outer surface of the antifouling layer (i.e., opposite to the white diffuse microporous layer) may be microstructured and / or nanostructured on some or all of its surface; for example, as described in PCT International Publication No. WO 2019 / 130198 and entitled “Anti-reflective surface structures”. In some embodiments, nanostructures may be superimposed on the microstructures on the surface of the antifouling layer.

[0128] The antifouling layer has a host surface (i.e., the antifouling surface) comprising micro- and / or nano-structures. The microstructures can be arranged as a series of alternating micro-peaks and micro-spaces. The size and shape of the micro-spaces between the micro-peaks can mitigate the adhesion of dirt particles to the micro-peaks. The nanostructures can be arranged as at least a series of nano-peaks disposed on at least the micro-spaces. Micro-peaks may be more resistant to environmental effects than nano-peaks. Because the micro-peaks are separated only by micro-spaces, and the micro-spaces are significantly higher than the nano-peaks, the micro-peaks can be used to protect the nano-peaks on the surface of the micro-spaces from abrasion.

[0129] Referring to the antifouling layer, the term or prefix "micro" refers to at least one dimension of a structure or shape defined 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. As used herein, the term or prefix "nano" refers to at least one dimension of a structure or shape defined in the range of less than 1 micrometer. For example, a nanostructure may have at least one of a height or width of less than 1 micrometer.

[0130] Figure 4A , Figure 4B and Figure 4C Cross-sections 400 and 401 of the anti-fouling surface structure are shown, illustrating an anti-fouling layer 408 having an anti-fouling surface 402 defined by a series of microstructures 418. Specifically, Figure 4A A perspective view of cross section 401 relative to the xyz axes is shown. Figure 4C The cross section 401 in the xz plane parallel to axis 410 is shown. Figure 4B The cross section 400 is shown in the yz plane, which is orthogonal to the cross section 401 and the axis 410. Figures 4A to 4C The anti-fouling surface 402 is shown, as if the anti-fouling layer 408 were located on a flat, horizontal surface. However, the anti-fouling layer 408 can be flexible and conformable to uneven substrates.

[0131] In some embodiments, microstructure 418 is formed within the antifouling layer 408. The microstructure 418 and the remainder of the antifouling layer 408 beneath it may be formed of the same material. The antifouling layer 408 may be formed of any suitable material capable of defining the microstructure 418, which may at least partially define the antifouling surface 402. The antifouling layer 408 may be transparent to light of various frequencies. In at least one embodiment, the antifouling layer 408 may be opaque or even non-transparent to light of various frequencies. In some embodiments, the antifouling layer 408 may comprise an ultraviolet (UV) stabilized material. In some embodiments, the antifouling layer 408 may comprise a polymeric material, such as a fluoropolymer or a polyolefin polymer.

[0132] The antifouling surface 402 may extend along axis 410, for example, parallel to or substantially parallel to the axis. Plane 412 may include axis 410, for example, parallel to or intersecting it, such that axis 410 lies within plane 412. Both axis 410 and plane 412 may be imaginary configurations used herein to illustrate various features associated with the antifouling surface 402. For example, the intersection of plane 412 and antifouling surface 402 may define features described as follows: Figure 4C The line 414 represents a cross-sectional profile of the surface, which includes micropeaks 420 and microspaces 422 as described in more detail herein. Line 414 may include at least one straight or curved segment. Line 414 may at least partially define a series of microstructures 418. Microstructures 418 may be three-dimensional (3D) structures disposed on the antifouling layer 408, and line 414 may describe only two dimensions (e.g., height and width) of the 3D structure. Figure 4B As can be seen, the microstructure 418 may have a length extending along the surface 402 from one side 430 to the other side 432.

[0133] Microstructure 418 may include a series of alternating micropeaks 420 and microspaces 422 along or in the direction of axis 410, which may be defined by or included in line 414. The direction of axis 410 may coincide with the width dimension. Microspaces 422 may each be disposed between a pair of micropeaks 420. In other words, multiple micropeaks 420 may be separated from each other by at least one microspace 422. In at least one embodiment, at least one pair of micropeaks 420 may not include the microspace 422 therebetween. The pattern of alternating micropeaks 420 and microspaces 422 may be described as a “skipped serration” (STR). Each of the micropeaks 420 and microspaces 422 may include at least one straight segment or a curved segment.

[0134] The slope of line 414 (e.g., increasing with extension) can be defined as the x-coordinate (extension) relative to the direction of axis 410 and as the y-axis (ascent) relative to the direction of plane 412. A maximum absolute slope can be defined for at least a portion of line 414. As used herein, the term "maximum absolute slope" refers to the maximum value selected from the absolute values ​​of slopes across a specific portion of line 414. For example, the maximum absolute slope of a microspace 422 can refer to the maximum value selected from the absolute values ​​of slopes calculated at each point along line 414 defining the microspace. The line defining the maximum absolute slope of each microspace 422 can be used to define an angle relative to axis 410. In some embodiments, the angle corresponding to the maximum absolute slope can be up to 30 degrees (in some embodiments, up to 25 degrees, 20 degrees, 15 degrees, 10 degrees, 5 degrees, or even up to 1 degree). In some embodiments, the maximum absolute slope of at least some (in some embodiments, all) of micropeaks 420 can be greater than the maximum absolute slope of at least some (in some embodiments, all) of microspaces 422.

[0135] In some embodiments, line 414 may include a boundary 416 between each adjacent micro-peak 420 and micro-space 422. Boundary 416 may include at least one of a straight segment or a curved segment. Boundary 416 may be a point along line 414. In some embodiments, boundary 416 may include a bend. A bend may include the intersection of two segments of line 414. A bend may include a point where line 414 changes direction in position (e.g., a change in slope between two different straight lines). A bend may also include a point where line 414 has the most abrupt change in direction in position (e.g., a sharper turn compared to an adjacent curved segment). In some embodiments, boundary 416 may include an inflection point. An inflection point may be a point on a line where the direction of curvature changes.

[0136] Figure 5An antifouling surface 402 of an antifouling layer 408 with nanostructures 530, 532 is shown, visible in two magnified stacks. At least one micropeak 420 may include at least one first microsegment 424 or at least one second microsegment 426. Microsegments 424, 426 may be disposed on the opposite side of the vertex 448 of the micropeak 420. Vertex 448 may be, for example, the highest point or local maximum of line 414. Each microsegment 424, 426 may include at least one: a straight segment or a curved segment.

[0137] The line 414 defining the first micro-segment 424 and the second micro-segment 426 may have a first average slope and a second average slope, respectively. The slope may be defined relative to the baseline 450 as the x-axis (extension), with the orthogonal direction being the z-axis (ascent). As used herein, the term "average slope" refers to the average slope over the entire specific portion of the line. In some embodiments, the average slope of the first micro-segment 424 may refer to the slope between the endpoints of the first micro-segment. In some embodiments, the average slope of the first micro-segment 424 may refer to the average of slopes measured at multiple points along the first micro-segment. Generally, the first average slope of a micro-peak may be defined as positive, and the second average slope of a micro-peak may be defined as negative. In other words, the first average slope and the second average slope have opposite signs. In some embodiments, the absolute value of the first average slope of a micro-peak may be equal to the absolute value of the second average slope of the micro-peak. In some embodiments, the absolute values ​​may be different. In some implementations, the absolute value of the average slope of each micro-segment 424, 426 may be greater than the absolute value of the average slope of micro-space 422.

[0138] Angle A of micro-peak 420 can be defined between a first average slope and a second average slope of the micro-peak. In other words, the first and second average slopes can be calculated, and then the angle between these calculated lines can be determined. For illustrative purposes, angle A is shown in relation to the first micro-segment 424 and the second micro-segment 426. However, in some embodiments, when the first and second micro-segments are not straight lines, angle A may not necessarily be equal to the angle between the two micro-segments 424, 426. Angle A can be within a range that provides sufficient antifouling properties for surface 402. In some embodiments, angle A can be up to 120 degrees (in some embodiments, up to 110 degrees, 100 degrees, 95 degrees, 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, or even up to 10 degrees). In some embodiments, angle A is at most 85 degrees (in some embodiments, at most 75 degrees). In some embodiments, angle A is at least 30 degrees at the lower end (in some embodiments, at least 25 degrees, 40 degrees, 45 degrees, or even at least 50 degrees). In some embodiments, angle A is at most 75 degrees at the upper end (in some embodiments, at most 60 degrees, or even at most 55 degrees).

[0139] Micropeak 420 can be any suitable shape capable of providing angle A based on the average slope of microsegments 424, 426. In some embodiments, micropeak 420 is typically formed in a triangular shape. In some embodiments, micropeak 420 is not triangular. The shape may be symmetric across the z-axis intersecting vertex 448. In some embodiments, the shape may be asymmetrical.

[0140] Each microspace 422 may define a microspace width 242. A microspace width 442 may be defined as the distance between corresponding boundaries 416, which may be between adjacent micropeaks 420. The minimum value of the microspace width 442 may be defined in micrometers. In some embodiments, the microspace width 442 may be at least 10 micrometers (in some embodiments, at least 20 micrometers, 25 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 75 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 150 micrometers, 200 micrometers, or even at least 250 micrometers). In some applications, the microspace width 442 is at least 50 micrometers at the lower end (in some embodiments, at least 60 micrometers). In some applications, the microspace width 442 is at most 90 micrometers at the upper end (in some embodiments, at most 80 micrometers). In some applications, the microspace width 442 is 70 micrometers.

[0141] As used herein, the term "peak distance" refers to the distance between consecutive peaks or between the nearest peak pairs, measured at each apex or highest point of a peak. The microspace width 442 may also be defined relative to the micro-peak distance 440. Specifically, the minimum value of the microspace width 442 may be defined relative to the corresponding micro-peak distance 440, which may refer to the distance between the nearest pair of micro-peaks 420 surrounding the microspace 422, measured at each apex 448 of the micro-peak. In some embodiments, the microspace width 442 may be at least 10% of the maximum value of the micro-peak distance 440 (in some embodiments, at least 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, or even at least 90%). In some embodiments, the minimum value of the microspace width 442 at the lower end is at least 30% of the maximum value of the micro-peak distance 440 (in some embodiments, at least 40%). In some embodiments, the minimum value of the microspace width 442 at the high end is at most 60% (in some embodiments, at most 50%) of the maximum value of the micropeak distance 440. In some embodiments, the microspace width 442 is 45% of the micropeak distance 440.

[0142] The minimum value of the micro-peak distance 440 can be defined in micrometers. In some embodiments, the micro-peak distance 440 can be at least 1 micrometer (in some embodiments, at least 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 10 micrometers, 25 micrometers, 50 micrometers, 75 micrometers, 100 micrometers, 150 micrometers, 200 micrometers, 250 micrometers, or even at least 500 micrometers). In some embodiments, the micro-peak distance 440 is at least 100 micrometers. The maximum value of the micro-peak distance 440 can be defined in micrometers. The micro-peak distance 440 can be up to 1000 micrometers (in some embodiments, up to 900 micrometers, 800 micrometers, 700 micrometers, 600 micrometers, 500 micrometers, 400 micrometers, 300 micrometers, 250 micrometers, 200 micrometers, 150 micrometers, 100 micrometers, or even up to 50 micrometers). In some embodiments, the micro-peak distance 440 is up to 200 micrometers at the high end. In some embodiments, the micro-peak distance 440 is at least 100 micrometers at the lower end. In some embodiments, the micro-peak distance 440 is 150 micrometers.

[0143] Each micropeak 420 may define a micropeak height 446. The micropeak height 446 may be defined as the distance between the baseline 550 and the apex 448 of the micropeak 420. The minimum value of the micropeak height 446 may be defined in micrometers. In some embodiments, the micropeak height 446 may be at least 10 micrometers (in some embodiments, at least 20 micrometers, 25 micrometers, 30 micrometers, 40 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 150 micrometers, 200 micrometers, or even at least 250 micrometers). In some embodiments, the micropeak height 446 is at least 60 micrometers (in some embodiments, at least 70 micrometers). In some embodiments, the micropeak height 446 is 80 micrometers.

[0144] Multiple nanostructures 530, 532 may be at least partially defined by line 414. Multiple nanostructures 530 may be disposed on at least one microspace 422. Specifically, the line 514 defining the nanostructures 530 may include at least a series of nanopeaks 520 disposed on at least one microspace 422. In some embodiments, at least one series of nanopeaks 520 of the multiple nanostructures 532 may also be disposed on at least one micropeak 420.

[0145] At least due to their size difference, the microstructure 418 may be more durable than the nanostructures 530 and 532 in terms of wear resistance. In some embodiments, the multiple nanostructures 532 are disposed only on the microspace 422, or at least not disposed near or adjacent to the vertex 448 of the micropeak 420.

[0146] Each nanopeak 520 may include at least one of a first nanosegment 524 and a second nanosegment 526. Each nanopeak 520 may include both nanosegments 524 and 526. Nanosegments 524 and 526 may be disposed on opposite sides of the apex 548 of the nanopeak 520. The first nanosegment 524 and the second nanosegment 526 may respectively define a first average slope and a second average slope, which describe the line 514 defining the nanosegment. For nanostructures 530 and 532, the slope of the line 514 may be defined relative to a baseline 550 as the x-axis (extension), where the orthogonal direction is the z-axis (ascent).

[0147] Generally, the first average slope of a nanopeak can be defined as positive, and the second average slope of a nanopeak can be defined as negative, or vice versa. In other words, the first average slope and the second average slope have at least opposite signs. In some embodiments, the absolute value of the first average slope of the nanopeak may be equal to the absolute value of the second average slope of the nanopeak (e.g., nanostructure 530). In some embodiments, the absolute values ​​may be different (e.g., nanostructure 532). Angle B of nanopeak 520 may be defined between the lines defined by the first average slope and the second average slope of the nanopeak. Similar to angle A, angle B, as shown in the figure, is for illustrative purposes and may not necessarily be equal to any directly measured angle between nanosections 524 and 526.

[0148] Angle B can be within a range that provides sufficient antifouling properties for surface 402. In some embodiments, angle B can be up to 120 degrees (in some embodiments, up to 110 degrees, 100 degrees, 90 degrees, 85 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, or even up to 10 degrees). In some embodiments, angle B is up to 85 degrees at the upper end (in some embodiments, up to 80 degrees, or even up to 75 degrees). In some embodiments, angle B is at least 55 degrees at the lower end (in some embodiments, at least 60 degrees, or even at least 65 degrees). In some embodiments, angle B is 70 degrees. For each nanopeak 520, angle B can be the same or different. For example, in some embodiments, the angle B of the nanopeak 520 on micropeak 420 can be different from the angle B of the nanopeak 520 on microspace 422.

[0149] The nanopeak 520 can be any suitable shape capable of providing an angle B based on a line defined by the average slope of nanosegments 524, 526. In some embodiments, the nanopeak 520 is typically formed in a triangular shape. In at least one embodiment, the nanopeak 520 is not triangular. The shape can be symmetrical across vertex 548. For example, the nanopeak 520 of the nanostructure 530 disposed on the microspace 422 can be symmetrical. In at least some embodiments, the shape can be asymmetrical. For example, the nanopeak 520 of the nanostructure 532 disposed on the micropeak 420 can be asymmetrical, where one nanosegment 524 is longer than the other nanosegment 526. In some embodiments, the nanopeak 520 can be formed without undercutting.

[0150] Each nanopeak 520 may define a nanopeak height 546. The nanopeak height 546 may be defined as the distance between the baseline 550 and the apex 548 of the nanopeak 520. The minimum value of the nanopeak height 546 may be defined in nanometers. In some embodiments, the nanopeak height 546 may be at least 10 nanometers (in some embodiments, at least 50 nanometers, 75 nanometers, 100 nanometers, 120 nanometers, 140 nanometers, 150 nanometers, 160 nanometers, 180 nanometers, 200 nanometers, 250 nanometers, or even at least 500 nanometers). In some embodiments, the nanopeak height 546 is at most 250 nanometers (in some embodiments, at most 200 nanometers), particularly for the nanostructure 530 on the microspace 422. In some embodiments, the nanopeak height 546 is in the range of 100 nanometers to 250 nanometers (in some embodiments, 160 nanometers to 200 nanometers). In some embodiments, the nanopeak height 546 is 180 nanometers.

[0151] In some embodiments, the nanopeak height 546 is at most 160 nanometers (in some embodiments, at most 140 nanometers), particularly for the nanostructure 532 on the micropeak 420. In some embodiments, the nanopeak height 546 is in the range of 75 nanometers to 160 nanometers (in some embodiments, 100 nanometers to 140 nanometers). In some embodiments, the nanopeak height 546 is 120 nanometers.

[0152] As used herein, the terms "corresponding micro-peak" or "corresponding micro-peaks" refer to a micro-peak 420 on which nano-peak 520 is disposed, or, if the nano-peak is disposed on a corresponding microspace 422, to one or both of the nearest micro-peaks surrounding said microspace. In other words, a micro-peak 420 corresponding to microspace 422 refers to a micro-peak among a series of micro-peaks preceding and following microspace.

[0153] The height of the nanopeak 546 may also be defined relative to the height of the micropeak 446 of the corresponding micropeak 420. In some embodiments, the corresponding micropeak height 446 may be at least 10 times the height of the nanopeak 546 (in some embodiments, at least 50 times, 100 times, 150 times, 200 times, 300 times, 400 times, 500 times, 600 times, 700 times, 800 times, 900 times, or even at least 1000 times). In some embodiments, the corresponding micropeak height 446 at the lower end is at least 300 times the height of the nanopeak 546 (in some embodiments, at least 400 times, 500 times, or even at least 600 times). In some embodiments, the corresponding micropeak height 446 at the upper end is at most 900 times the height of the nanopeak 546 (in some embodiments, at most 800 times or even at most 700 times).

[0154] The nano-peak distance 540 can be defined between nano-peaks 520. The maximum value of the nano-peak distance 540 can be defined. In some embodiments, the nano-peak distance 540 can be up to 1000 nanometers (in some embodiments, up to 750 nanometers, 700 nanometers, 600 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even up to 100 nanometers). In some embodiments, the nano-peak distance 540 is up to 400 nanometers (in some embodiments, up to 300 nanometers). The minimum value of the nano-peak distance 540 can be defined. In some embodiments, the nano-peak distance 540 can be at least 1 nanometer (in some embodiments, at least 5 nanometers, 10 nanometers, 25 nanometers, 50 nanometers, 75 nanometers, 100 nanometers, 150 nanometers, 200 nanometers, 250 nanometers, 300 nanometers, 350 nanometers, 400 nanometers, 450 nanometers, or even at least 500 nanometers). In some embodiments, the nanopeak distance 540 is at least 150 nanometers (in some embodiments, at least 200 nanometers). In some embodiments, the nanopeak distance 540 is in the range of 150 nanometers to 400 nanometers (in some embodiments, 200 nanometers to 300 nanometers). In some embodiments, the nanopeak distance 540 is 250 nanometers.

[0155] The nanopeak distance 540 may be defined relative to the micropeak distance 440 between the corresponding micropeaks 420. In some embodiments, the corresponding micropeak distance 440 is at least 10 times the nanopeak distance 540 (in some embodiments, at least 50 times, 100 times, 200 times, 300 times, 400 times, 500 times, 600 times, 700 times, 800 times, 900 times, or even at least 1000 times). In some embodiments, the corresponding micropeak distance 440 at the lower end is at least 200 times the nanopeak distance 540 (in some embodiments, at least 300 times). In some embodiments, the corresponding micropeak distance 440 at the upper end is at most 500 times the nanopeak distance 540 (in some embodiments, at most 400 times).

[0156] In some embodiments of forming an antifouling surface, the method may include extruding a hot-melt material having a UV-stabilized material. The extruded material may be shaped using a microreplication tool. The microreplication tool may include a series of mirror images of microstructures that can form a series of microstructures on the surface of the antifouling layer 408. The series of microstructures may include a series of alternating micropeaks and microspaces along an axis. Multiple nanostructures may be formed on the surface of the layer at least in the microspaces. The multiple nanopeaks may include at least one series of nanopeaks along an axis.

[0157] In some implementations, multiple nanostructures can be formed by exposing the surface to reactive ion etching. For example, masking elements can be used to define nanopeaks.

[0158] In some implementations, multiple nanostructures can be formed by shaping extruded material using a micro-replication tool that also incorporates ion-etched diamond. This method may involve providing a diamond tool, wherein at least a portion of the tool comprises a plurality of cutting tips, wherein the spacing between the cutting tips may be less than 1 micrometer; and cutting a substrate with the diamond tool, wherein the diamond tool can enter and exit along a certain direction at a spacing (p1). The diamond tool may have a maximum cutter width (p2), and

[0159] Nanostructures can be characterized as being embedded within the microstructured surface of the antifouling layer 408. Except for the portion of the nanostructure exposed to air, the shape of the nanostructure is typically defined by the adjacent microstructured material.

[0160] Microstructured surface layers, including nanostructures, can be formed using multi-head diamond tools. Diamond turning (DTM) machines can be used to generate micro-replicating tools that produce anti-fouling surface structures including nanostructures, as described in U.S. Patent Application Publication No. 2013 / 0236697 (Walker et al.). Microstructured surfaces, also including nanostructures, can be formed using multi-head diamond tools, which may have a single radius, wherein the multiple heads are spaced less than 1 micrometer apart. Such multi-head diamond tools can also be referred to as “nanostructured diamond tools.” Therefore, microstructured surfaces (where the microstructures also include nanostructures) can be formed simultaneously during the diamond tooling process of the microstructured tool. Focused ion beam milling processes can be used to form the heads, and also to form the valleys of the diamond tool. For example, focused ion beam milling can be used to ensure that the inner surfaces of the heads converge along a common axis to form the bottom of the valley. Focused ion beam milling can be used to form features in valleys, such as recessed or raised arcuate ellipses, parabolas, mathematically defined surface patterns, or random or pseudo-random patterns. Valleys of a variety of other shapes can also be formed. Exemplary diamond turning machines and methods for producing discontinuous or inconsistent surface structures may include and utilize rapid tool servo mechanisms (FTS) as described in the following patents: for example, PCT Publication No. WO 00 / 48037 (Campbell et al.); U.S. Patent Nos. 7,350,442 (Ehnes et al.) and 7,328,638 (Gardiner et al.); and U.S. Patent Publication No. 2009 / 0147361 (Gardiner et al.).

[0161] In some implementations, multiple nanostructures can be formed by shaping an extruded material or antifouling layer 408 using a micro-replicating tool that also has a nanostructured granular electroplated layer for imprinting. Electrodeposition, or more specifically electrochemical deposition, can also be used to generate various surface structures, including nanostructures, to form the micro-replicating tool. The tool can be made using a two-part electroplating process, wherein a first electroplating process forms a first metal layer having a first master surface, and a second electroplating process forms a second metal layer on the first metal layer. The second metal layer may have a second master surface with an average roughness less than that of the first master surface. The second master surface can serve as the structured surface of the tool. A replica of this surface can then be prepared in the master surface of an optical film to provide light-diffusing properties. An example of an electrochemical deposition technique is described in PCT Publication No. WO 2018 / 130926 (Derks et al.).

[0162] Figure 6 A cross-section 600 of an antifouling layer 608 having an antifouling surface 602 is shown. The antifouling surface 602 may be similar to the antifouling surface 402; for example, the microstructures 418, 618 of the antifouling layers 408, 608 may have the same or similar dimensions, and may also form a skipped, toothed ridge pattern of alternating micropeaks 620 and microspaces 622. The antifouling surface 602 differs from surface 402 in that, for example, the nanostructures 720 may include nanoscale masking elements 722.

[0163] The nanostructure 720 can be formed using a masking element 722. For example, the masking element 722 can be used in subtractive manufacturing processes, such as reactive ion etching (RIE), to form the nanostructure 720 having a surface 602 with microstructure 618. Methods for preparing nanostructures and nanostructured articles can involve depositing layers (such as an antifouling layer 408) onto a host surface of a substrate by plasma chemical vapor deposition from a gaseous mixture while simultaneously etching the surface with a reactive material substantially simultaneously. This method may include providing a substrate; mixing a first gaseous material capable of depositing layers onto the substrate when a plasma is formed with a second gaseous material capable of etching the substrate when a plasma is formed, thereby forming a gaseous mixture. This method may include forming a plasma from the gaseous mixture and exposing the surface of the substrate to the plasma, wherein the surface can be etched and layers can be deposited substantially simultaneously on at least a portion of the etched surface, thereby forming the nanostructure.

[0164] The substrate can be a (co)polymer material, inorganic material, alloy, solid solution, or a combination thereof. The deposited layer can include reaction products deposited using a plasma chemical vapor deposition process with a reactive gas, comprising compounds selected from the group consisting of organosilicon compounds, metal alkyl compounds, metal isopropoxy compounds, acetylacetone metal compounds, metal halides, and combinations thereof. High aspect ratio nanostructures can be fabricated, optionally exhibiting random dimensions in at least one dimension, or even in three orthogonal dimensions.

[0165] In some embodiments, an antifouling layer 608 may be provided having a series of microstructures 618 disposed on an antifouling surface 602 of the layer. The series of microstructures 618 may include a series of alternating micropeaks 620 and microspaces 622.

[0166] A series of nanoscale masking elements 722 may be disposed on at least the microspace 622. The antifouling surface 602 of the antifouling layer 608 may be exposed to reactive ion etching to form a plurality of nanostructures 718 on the surface of the layer comprising a series of nanopeaks 720. Each nanopeak 720 may include a masking element 722 and a pillar 760 of layer material between the masking element 722 and the layer 608. The masking element 722 may be formed of any suitable material that is more resistant to the RIE effect than the material of the antifouling layer 608. In some embodiments, the masking element 722 comprises an inorganic material. Non-limiting examples of inorganic materials include silica and silicon dioxide. In some embodiments, the masking element 722 is hydrophilic. Non-limiting examples of hydrophilic materials include silica and silicon dioxide.

[0167] As used herein, the term "maximum diameter" refers to the longest dimension based on a straight line passing through an element of any shape. The masking element 722 may be nanometer-sized. Each masking element 722 may define a maximum diameter 742. In some embodiments, the maximum diameter of the masking element 722 may be up to 1000 nanometers (in some embodiments, up to 750 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even up to 100 nanometers). The maximum diameter 742 of each masking element 722 may be described relative to the peak height 640 of the corresponding peak 620. In some embodiments, the corresponding peak height 640 is at least 10 times the maximum diameter 742 of the masking element 722 (in some embodiments, at least 25 times, 50 times, 100 times, 200 times, 250 times, 300 times, 400 times, 500 times, 750 times, or even at least 1000 times).

[0168] Each nanopeak 720 may have a defined height 722. The height 722 may be defined between the baseline 750 and the apex 748 of the masking element 722.

[0169] Figure 7A and Figure 7B Lines 800 and 820 are shown, representing cross-sectional profiles of peaks 802 and 822 in different forms for any antifouling surface (such as surfaces 402, 602), which may be micro-peaks of microstructures or nano-peaks of nanostructures. As mentioned, the structure does not need to be strictly triangular in shape. Line 800 shows that the first portion 804 (top portion) of peak 802, including vertex 812, may have a generally triangular shape, while the adjacent side portions 806 may be curved. In some embodiments, as shown, the side portions 806 of peak 802 may not have a more abrupt turn when transitioning into space 808. The boundary 810 between the side portions 806 of peak 802 and space 808 may be defined by the threshold slope of line 800, as described herein, for example, relative to... Figures 4A to 4C and Figure 5 The subject of discussion.

[0170] Space 808 may also be defined by its height relative to the height 814 of peak 802. The height 814 of peak 802 may be defined between one of the boundaries 810 and vertex 812. The height of space 808 may be defined between the bottom 816 or the lowest point of space 808 and one of the boundaries 810. In some embodiments, the height of space 808 may be up to 40% of the height 814 of peak 802 (in some embodiments, up to 30%, 25%, 20%, 15%, 10%, 5%, 4%, 3%, or even up to 2%). In some embodiments, the height of space 808 is up to 10% of the height 814 of peak 802 (in some embodiments, up to 5%, 4%, 3%, or even up to 2%).

[0171] Line 820 illustrates that the first portion 824 (top portion) of peak 820, including the vertex, may have a generally circular shape, while there are no sharp turns between adjacent sides 826. Vertex 832 may be defined as the highest point of structure 820, for example, where the slope changes from positive to negative. Although the first portion 824 (top portion) may be circular at vertex 832, peak 820 may still define an angle between a first average slope and a second average slope, such as angle A (see...). Figure 5 The boundary 830 between the side 826 of peak 820 and space 828 may be defined, for example, by a more abrupt turn. The boundary 830 may also be defined by slope or relative height, as described herein.

[0172] like Figures 8 to 11 As shown, the antifouling surface can be discontinuous, intermittent, or inconsistent. For example, the antifouling surface can also be described as comprising micropyramids having microspaces surrounding the micropyramids (see [reference]). Figure 8 and Figure 11 ).

[0173] Figure 8A first antifouling surface 1001, at least partially defined by inconsistent microstructures 1210, is shown. For example, if the antifouling surface 1000 is observed in the yz plane (similar to...), Figure 4B If at least one micro-peak 1012 has an inconsistent height from left to right in the view, this can be compared with micro-peak 420, which shows a consistent height from left to right in the view. Figure 4B This creates a contrast. Specifically, at least one of the height or shape of the micropeaks 1012 defined by the microstructure 1010 may be inconsistent. The micropeaks 1012 are separated by microspaces (not shown in this perspective view), similar to other surfaces described herein, such as the microspaces 422 of surface 402. Figure 4A and Figure 4C ).

[0174] Figure 9 A second antifouling surface 1002 with a discontinuous microstructure 1020 is shown. For example, if the antifouling surface 1002 is observed in the yz plane (similar to...), Figure 4B This can be illustrated by showing more than one nanopeak 1022 spaced apart by microstructure 1020, which can be compared with the micropeak 420 shown extending continuously from the left to the right side of the view. Figure 4B In contrast, specifically, the micropeaks 1022 of the microstructure 1020 may be surrounded by microspaces 1024. Each micropeak 1022 may have a semi-dome shape. For example, the semi-dome shape may be hemispherical, semi-oval, semi-oblong, or semi-flattened spherical. The edge 1026 of the base of each micropeak 1022 extending around each micropeak may be circular (e.g., circular, elliptical, or rounded rectangle). The shapes of the micropeaks 1022 may be uniform, as depicted in the illustrated embodiments, or they may be inconsistent.

[0175] Figure 10 and Figure 11 It is the first part 1004 of the third antifouling surface 1003 with a discontinuous microstructure 1030. Figure 10 Part 2 and Part 1005 Figure 11 Both are perspective views. Figure 10 The view shows more of the "front" side of microstructure 1030 at an angle close to 45 degrees, while Figure 11The view shows some of the "back" sides of the microstructures closer to the apex. The micro-peaks 1032 of the microstructure 1030, surrounded by microspaces 1034, may have a pyramidal shape (e.g., a micropyramid). For example, the pyramidal shape may be a rectangular pyramid or a triangular pyramid. The sides 1036 of the pyramidal shape may be inconsistent in shape or area (as shown in the illustrated embodiment) or may be consistent in shape or area. The edges 1038 of the pyramidal shape may be non-linear (as shown in the illustrated embodiment) or may be linear. The total volume of each micro-peak 1032 may be inconsistent, as depicted in the illustrated embodiment, or may be consistent.

[0176] Multilayer films can be advantageous because the physical and chemical properties of the top surface of the film differ from those of the bottom surface. For example, highly fluorinated polymers are beneficial for stain resistance, chemical resistance, and antifouling properties, but inherently do not adhere well to other polymers or adhesives. A first fluoropolymer layer 1501 with a high tetrafluoroethylene (TFE) content has a high fluorine content and can therefore be advantageous as a microstructured surface layer in the articles described herein. A second fluoropolymer layer 1502 may have a lower TFE content and still adhere well to the first fluoropolymer layer 1501. If the second fluoropolymer layer also includes vinylidene fluoride (VDF), it will adhere well to other fluoropolymers that include VDF, such as polyvinylidene fluoride (PVDF). If the second or third fluoropolymer layer 1503 includes sufficient VDF, it will adhere well to the non-fluorinated polymer layer 1504, such as acrylate polymers and even urethane polymers. Multilayer fluoropolymer membranes that can be used for antifouling surface-structured membranes with a highly fluorinated top surface layer and a less fluorinated bottom surface layer are described in PCT Publication No. WO2017 / 172564 (Hebrink et al.).

[0177] Antistatic agents can also be incorporated into the antifouling layer to reduce unwanted attraction to dust, dirt, and debris. Ionic antistatic agents (e.g., available under the trade names “3M IONIC LIQUID ANTI-STAT FC-4400” or “3M IONIC LIQUID ANTI-STAT FC-5000” from 3M Company) can be incorporated into the PVDF fluoropolymer layer to provide electrostatic dissipation. Antistatic agents for PMMA and CoPMMA optical polymer layers are available from STTRAITE of Lubrizol Engineered Polymers, Brecksville, OH. Additional antistatic agents for PMMA and CoPMMA optical polymer layers are available from PELESTAT of Sanyo Chemical Industries, Tokyo, Japan. Optionally, the antistatic properties may include a transparent conductive coating, such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), metal nanowires, carbon nanotubes, or graphene thin films, any of which may be disposed on or coated onto one of the layers of the antifouling surface structured film described herein.

[0178] Preferably, the hard coating or film layer, protective layer, or antifouling layer comprises ceramic or glass beads, ceramic or glass bubbles, or combinations thereof. For example, ceramic or glass beads and / or ceramic or glass bubbles are hard particles that may be present on a surface (e.g., outer) layer to provide scratch resistance. In some embodiments, such beads and / or bubbles may even protrude from the surface as hemispheres or even quarter-spheres.

[0179] See now Figures 13A to 13E The outer surface 300 of the outer layer (e.g., protective layer) 202 of the radiation-cooled article may include a structure that provides high light absorption in the atmospheric window region. Specifically, the dimensions of this structure may be appropriately set to increase the light absorption of the radiation-cooled article (e.g., Figure 2 The absorbance of 200). The surface 300 of the outer layer 202 is at 200. Figure 13A As can be seen in the top view, multiple structures 302 may be disposed in or on the surface of at least one of these layers (such as the outer layer 202). These structures may be uniformly distributed in at least one of these layers (such as the outer layer 202). In some embodiments, the structures 302 may be disposed in or on the surface and uniformly distributed in at least one of these layers. The arrangement of the structures 302 may be described as an array, which may be two-dimensional or three-dimensional.

[0180] Structure 302 may include inorganic particles. For example, each depicted structure 302 may correspond to one inorganic particle. The inorganic particle may be dispersed in or disposed on at least one layer. The inorganic particles may include titanium dioxide, silicon dioxide, zirconium oxide, or zinc oxide. The inorganic particles may be in the form of nanoparticles, including: nano-titanium dioxide, nano-silicon dioxide, nano-zirconia, or even nano-sized zinc oxide particles. The inorganic particles may be in the form of beads or microspheres. The inorganic particles may be formed from ceramic materials, glass, or various combinations thereof. In some embodiments, the inorganic particle has an effective D90 particle size of at least 1 micrometer (in some embodiments, at least 3 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, 10 micrometers, or even at least 13 micrometers). In some embodiments, the inorganic particle has an effective D90 particle size of up to 40 micrometers (in some embodiments, up to 25 micrometers, 20 micrometers, 15 micrometers, 14 micrometers, 13 micrometers, 12 micrometers, 11 micrometers, 10 micrometers, 9 micrometers, or even up to 8 micrometers). As defined in NIST's "Particle Size Characterization," ASTM E-2578-07 (2012) describes D90 as the intercept in which 90% of the sample mass has particles with a diameter smaller than that value. For example, a D90 of 10 micrometers specifies that 90% of the sample mass includes particles with a diameter smaller than 10 micrometers. Particle size can be measured using a particle size analyzer (e.g., the "HORIBA PARTICLE SIZE ANALYZER," available under the trade name from Flow Sciences, Inc., Leland, NC, North Carolina).

[0181] Suitable ceramic microspheres can be purchased from 3M under the trade names "3M CERAMIC MICROSPHERES WHITE GRADE W-210" (alkali aluminosilicate ceramic, effective D90 particle size of 12 microns), "3M CERAMIC MICROSPHERES WHITE GRADE W-410" (alkali aluminosilicate ceramic, effective D90 particle size of 21 microns), and "CERAMIC MICROSPHERES WHITE GRADE W-610" (alkali aluminosilicate ceramic, effective D90 particle size of 32 microns), or various combinations thereof. Generally, various combinations of inorganic particles of the same or different sizes can be used.

[0182] Structure 302 may include a surface structure. This surface structure may be disposed on a surface (such as surface 300 of outer layer 202). In some embodiments, the surface structure may be integrated into or incorporated onto the surface. For example, as described in International Publication No. WO 2019 / 130199 (Hebrink et al.), the surface structure may be formed by extrusion replication or microreplication on at least one layer of a radiation-cooled article. The surface structure may or may not be formed of the same material as the at least one layer.

[0183] As in Figures 13B to 13E As can be seen, surface structures 304, 305, 306, and 307 may define first widths 311, 321, 331, and 341 and second widths 313, 323, 333, and 343. The first widths 311, 321, 331, and 341 may be described as outer widths, and the second widths 313, 323, 333, and 343 may be described as base widths. In some embodiments, surface structures 304, 305, 306, and 307 may have an average width in the range of 1 micrometer to 40 micrometers, which may be beneficial for emissivity or absorbance in the atmospheric window region. Surface structures 304, 305, 306, and 307 may include sidewalls 324, 325, 326, and 327 defining each width 311, 313, 321, 323, 331, 333, 341, and 343. Sidewalls 324, 325, 326, and 327 can adopt various geometries. Some geometries are particularly suitable for certain manufacturing processes. These geometries can be defined by cross-sections extending between first widths 311, 321, 331, and 341 and second widths 313, 323, 333, and 343. Surface structures 304, 305, and 306 can be described as conical or having a tapered shape. As used herein, the term "width" can refer to, for example, the diameter of these structures when the cross-section of structures 304, 305, and 306 is circular, elliptical, or tapered. Figure 13B In the surface structure 304, the cross-section of the sidewall 324 may include at least one straight line between widths 311 and 313. The first width 311 may be smaller than the second width 313 to define the slope. Figures 13C to 13D In the process, the cross-sections of the sidewalls 325 and 326 of the surface structures 305 and 306 may respectively include at least one curve or arc between the corresponding first width and second width 321, 323 and 331, 333. Figure 13C In the middle, the width 321 is not zero to give the surface structure 305 a tapered cylindrical shape. Figure 13D In this context, the width 331 is equal to zero to give the surface structure 306 a hemispherical shape. In some embodiments, the surface structure 306 may be spherical, or even ellipsoidal. For example, in... Figure 13EAs can be seen, surface structure 307 can be described as a square or rectangular column. The cross-section of the sidewall 327 of surface structure 307 may include a straight line between widths 341 and 343 (as shown), or may even include at least one curve or arc between these widths. The sidewall 327 may define a slope, wherein the first width 341 is less than the second width 343 (as shown), or the sidewall may even be vertical, wherein the first width and the second width are equal.

[0184] Each structure 304, 305, 306, 307 may protrude from surface 300 orthogonally to the height of the surface extension. The width of each structure 304, 305, 306, 307 may be defined to be orthogonal to the height and parallel to surface 300. In some embodiments, each surface structure 304, 305, 306, 307 has an average width of at least 1 micrometer (in some embodiments, at least 3 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, or even at least 10 micrometers). In some embodiments, each surface structure 304, 305, 306, 307 has an average width of up to 50 micrometers (in some embodiments, up to 20 micrometers, 15 micrometers, 14 micrometers, 13 micrometers, 12 micrometers, 11 micrometers, 10 micrometers, 9 micrometers, or even up to 8 micrometers). In some embodiments, each surface structure 304, 305, 306, 307 has an average height of at least 1 micrometer (in some embodiments, at least 3 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 8 micrometers, 9 micrometers, or even at least 10 micrometers). In some embodiments, each surface structure 304, 305, 306, 307 has an average height of up to 50 micrometers (in some embodiments, up to 20 micrometers, 15 micrometers, 14 micrometers, 13 micrometers, 12 micrometers, 11 micrometers, 10 micrometers, 9 micrometers, or even up to 8 micrometers).

[0185] Transparent adhesive bonding layer

[0186] Suitable transparent adhesives for use in one or more bonding layers include, for example, pressure-sensitive adhesives. Suitable classes of pressure-sensitive adhesives include acrylics, tackifying rubbers, tackifying synthetic rubbers, vinyl acetate, etc. Suitable acrylic adhesives are disclosed, for example, in U.S. Patent Nos. 3,239,478 (Harlan); 3,935,338 (Robertson); 5,169,727 (Boardman); 4,952,650 (Young et al.); and 4,181,752 (Martens et al.), which are incorporated herein by reference.

[0187] In the selected embodiments, the transparent adhesive is optically transparent, meaning that the adhesive has both transparency and clarity (e.g., low haze). In some embodiments, the optically transparent adhesive (OCA) is selected from acrylates, polyurethanes, polyolefins (such as polyisobutylene (PIB)), silicones, or combinations thereof. Exemplary OCAs include those described in the following: International Publication No. WO 2008 / 128073 (Everaerts et al.) relating to an antistatic, optically transparent pressure-sensitive adhesive; U.S. Patent Application Publication No. US 2009 / 089137 (Sherman et al.) relating to a stretch-release OCA; US 2009 / 0087629 (Everaerts et al.) relating to an OCA compatible with indium tin oxide; US 2010 / 0028564 (Cheng et al.) relating to an antistatic optical structure having a light-transmitting adhesive; US 2010 / 0040842 (Everaerts et al.) relating to an adhesive compatible with a corrosion-sensitive layer; US 2011 / 0126968 (Dolezal et al.) relating to an optically transparent stretch-release tape; and U.S. Patent No. 8,557,378 (Yamanaka et al.) relating to a stretch-release tape. Suitable OCAs include optically clear acrylic pressure-sensitive adhesives, such as 3M OCA 8146, 8211, 8212, 8213, 8214 and 8215, each available from 3M Company, St. Paul, MN.

[0188] In some embodiments, the transparent adhesive is resistant to UV radiation damage. Exemplary adhesives that are generally resistant to UV radiation damage include silicone adhesives and acrylic adhesives containing UV stabilizers / blockers. For example, U.S. Patent No. 5,504,134 (Palmer et al.) describes mitigating UV-induced degradation of polymer substrates by using metal oxide particles with a size ranging from about 0.001 micrometers to about 0.2 micrometers (in some embodiments, from about 0.01 micrometers to about 0.15 micrometers). U.S. Patent No. 5,876,688 (Laundon) describes a method for producing micronized zinc oxide that is small enough to be transparent when incorporated as a UV blocker and / or scattering agent into paints, coatings, finishes, plastics, cosmetics, etc., and micronized zinc oxide is well-suited for use in this invention. These fine particles (such as zinc oxide and titanium oxide) that can reduce UV radiation, with a particle size in the range of 10 nm to 100 nm, are available from companies such as Kobo Products, Inc., South Plainfield, NJ.

[0189] UV reflector

[0190] The optional ultraviolet-reflective layer is typically a UV-reflective multilayer optical film that has a reflectivity of at least 50% for vertically incident ultraviolet radiation with wavelengths in the range of at least 340 nm but less than 400 nm. In some embodiments, the ultraviolet-reflective layer has a reflectivity of at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or even at least 98% for vertically incident ultraviolet radiation with wavelengths in the range of at least 340 nm but less than 400 nm. This reflectivity is advantageously used to reduce ultraviolet radiation damage (e.g., photodegradation by sunlight) to white diffuse-reflective microporous layers, especially layers comprising polyethylene terephthalate (PET) polyester.

[0191] The ultraviolet reflective layer can be a UV-reflective multilayer optical film, many of which are known in the art. Such UV-reflective MOFs typically comprise alternating layers of different polymers with different refractive indices and appropriate layer thicknesses. Figure 3 An exemplary UV-reflective multilayer optical film 320 is shown, which can also be used as a reflector for visible light and / or infrared wavelengths, depending on the configuration of the optical layers. The UV-reflective multilayer optical film 320 includes one or more first optical layers 312, one or more second optical layers 314, and optionally one or more UV / VIS transparent additional surface layers 318.

[0192] UV-reflective multilayer optical film 320 comprises a multilayer optical stack 308 having alternating layers 312, 314 of at least two materials (typically comprising different polymers). The in-plane refractive index n1 of the high-refractive-index layer 312 in one plane direction is higher than the in-plane refractive index n2 of the low-refractive-index layer 314 in the same plane direction. The difference in refractive index at each boundary between layers 312, 314 causes partial reflection of incident light. The transmission and reflection characteristics of the multilayer optical film 320 are based on the coherent interference of light caused by the difference in refractive index between layers 312, 314 and the thickness of layers 312, 314. When the effective refractive index (or the in-plane refractive index perpendicular to the angle of incidence) differs between layers 312, 314, a reflective surface is formed at the interface between adjacent layers 312, 314. The reflectivity of the reflective surface depends on the square of the difference in effective refractive index between layers 312, 314 (e.g., (n1-n2)). 2 By increasing the refractive index difference between layers 312 and 314, improved optical power (higher reflectivity), thinner films (thinner or fewer layers) and wider bandwidth performance can be obtained. In one exemplary embodiment, the refractive index difference in an in-plane direction is at least about 0.05, preferably greater than about 0.10, more preferably greater than about 0.15, and even more preferably greater than about 0.20.

[0193] In some embodiments, the materials of layers 312 and 314 inherently have different refractive indices. In another embodiment, the material of at least one layer 312 or 314 has stress properties that induce birefringence, such that the refractive index (n) of the material is affected by the stretching process. By stretching the multilayer optical film 320 within a range of uniaxial to biaxial orientations, films with a range of reflectivities for plane-polarized incident light of different orientations can be produced.

[0194] For reasons of film thickness, flexibility, and economy, the number of layers in the UV reflective multilayer optical film 320 is selected to achieve the desired optical properties using the minimum number of layers. For reflective films such as mirrors, the number of layers is preferably less than about 2,000, more preferably less than about 1,000, and even more preferably less than about 750. In some embodiments, the number of layers is at least 150 or 200. In other embodiments, the number of layers is at least 250.

[0195] In some embodiments, the UV-reflective multilayer optical film 320 also includes optional additional non-optical layers or optical surface layers. The optical surface layer 318 protects the optical layers 312, 314 from damage, facilitates co-extrusion processing, and / or improves post-processing mechanical properties. The additional surface layer 318 is typically thicker than the optical layers 312, 314. The thickness of the surface layer 318 is typically at least two times, preferably at least four times, and more preferably at least ten times the thickness of the individual optical layers 312, 314. The thickness of the surface layer 318 can be varied to prepare a UV-reflective multilayer optical film with a specific thickness. A bonding layer (not shown) may optionally be present between the surface layer and the optical layers. Additionally, an optional top coating may be disposed on the surface layer. One or more additional layers 318 are typically disposed such that at least a portion of the light transmitted, polarized, and / or reflected by the optical layers 312, 314 also passes through the additional layer (i.e., the additional layer is disposed in the path of light passing through or reflected by the optical layers 312, 314). To provide a certain degree of antifouling properties, one or two of the surface layers (preferably at least the outermost layer) contain a fluoropolymer.

[0196] The UV-reflective multilayer optical film 320 comprises multiple pairs of low / high refractive index layers, wherein the combined optical thickness of each low / high refractive index layer pair 312, 314 is half the center wavelength of the spectral band it is designed to reflect. Stacks of such films are commonly referred to as quarter-wavelength stacks. In some embodiments, different low / high refractive index layer pairs may have different combined optical thicknesses, such as in the case of optical films requiring broadband reflection.

[0197] Each component layer of the UV-reflective multilayer optical film 320, whether surface or optical, is preferably resistant to ultraviolet radiation. Many fluoropolymers are resistant to UV radiation. Examples of usable fluoropolymers include copolymers of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (e.g., available under the trade name 3M DYNEON THV from 3M Company); copolymers of TFE, HFP, vinylidene fluoride, and perfluoropropyl vinyl ether (PPVE) (e.g., available under the trade name 3M DYNEON THVP from 3M Company); polyvinylidene fluoride (PVDF) (e.g., available under the trade name 3M DYNEON PVDF 6008 from 3M Company); ethylene-trifluorochloroethylene polymer (ECTFE) (e.g., available under the trade name HALAR350LC ECTFE from Solvay, Brussels, Belgium); and ethylene-tetrafluoroethylene copolymer (ETFE) (e.g., available under the trade name 3M DYNEON ETFE 6235 from 3M Company). Company); perfluoroalkoxyalkylene polymers (PFA); fluorinated ethylene propylene copolymers (FEP); polytetrafluoroethylene (PTFE); copolymers of TFE, HFP, and ethylene (HTE) (e.g., 3M DYNEON HTE1705, available from 3M Company). Combinations of fluoropolymers may also be used. In some embodiments, the fluoropolymers include FEP. In some embodiments, the fluoropolymers include PFA.

[0198] Examples of non-fluorinated polymers that can be used in at least one layer of the UV-reflective multilayer optical film 320 include at least one of the following: polypropylene, polyethylene, polyethylene copolymers, polyethylene methacrylate copolymers, ethylene vinyl acetate copolymers, polymethyl methacrylate, methyl methacrylate copolymers (e.g., copolymers of ethyl acrylate and methyl methacrylate), polyurethane, extended-chain polyethylene polymers (ECPE), or combinations thereof. Generally, combinations of non-fluorinated polymers can be used. Exemplary non-fluorinated polymers, particularly those for high-refractive-index optical layers, may include homopolymers of polymethyl methacrylate (PMMA), such as those available from Ineos Acrylics, Inc., Wilmington, DE (CP71 and CP80); and polyethyl methacrylate (PEMA) having a lower glass transition temperature than PMMA. Additional available polymers include: copolymers of methyl methacrylate, such as copolymers made of, for example, 75% by weight methyl methacrylate and 25% by weight ethyl acrylate, such as those available as PERSPEX CP63 from Ineos Acrylics, Wilmington, Delaware, or those available as ALTUGLAS 510 from Arkema, Philadelphia, PA, and copolymers of methyl methacrylate monomer units and n-butyl methacrylate monomer units. Blends of PMMA and PVDF may also be used.

[0199] Suitable triblock acrylic copolymers may be available, for example, as KURARITY LA4285 from Kuraray America Inc., Houston, TX. Additional suitable polymers for optical layers, particularly for refractive index optical layers, may include at least one of the following: polyolefin copolymers, such as poly(ethylene-co-octene) (e.g., ENGAGE 8200 from Dow Elastomers, Midland, MI); polyethylene methacrylate (e.g., ELVALOY from Dow Elastomers); poly(propylene-co-ethylene) (e.g., Z9470 from Atofina Petrochemicals, Inc., Houston, TX); and copolymers of atactic and isotactic polypropylene. Materials may be selected based on the absorptivity or transmittance characteristics described herein and based on refractive index. Generally speaking, the greater the refractive index between two materials, the thinner the film can be, which is ideal for effective heat transfer.

[0200] Multilayer optical films (including reflective polarizers and mirrors), such as those described in the following, can be prepared by co-extruding alternating polymer layers with different refractive indices: U.S. Patent Nos. 5,882,774 (Jonza et al.); 6,045,894 (Jonza et al.); 6,368,699 (Gilbert et al.); 6,531,230 (Weber et al.); 6,667,095 (Wheatley et al.); 6,783,349 (Neavin et al.); 7,271,951B2 (Weber et al.); 7,632,568 (Padiyath et al.); 7,652,736 (Padiyath et al.); and 7,952,805 (McGurran et al.); and PCT Publications WO 95 / 17303 (Ouderkirk et al.) and WO 99 / 39224 (Ouderkirk et al.).

[0201] In a preferred embodiment, the UV-reflective multilayer optical film reflects wavelengths in the 340 nm to 400 nm range and is composed of a 150 high refractive index layer comprising a methyl methacrylate copolymer (CoPMMA) (e.g., PERSPEX CP63 available from Lucite International, Cordova, Tennessee) and a 150 low refractive index layer comprising a fluoropolymer (e.g., 3M DYNEON THV221 available from 3M Company).

[0202] Infrared reflective layer

[0203] The radiation-cooled article optionally includes an infrared reflective layer disposed between the white diffuse microporous layer and the non-white colored reflective film, or disposed adjacent to the non-white colored reflective film and opposite to the white diffuse microporous layer. The optional infrared reflective layer functions to reduce (by reflection) the amount of IR thermal radiation generated by the reflective microporous film and transmitted toward any substrate intended to be cooled by the radiation-cooled article.

[0204] The optional infrared reflective layer may be made of any material having an average reflectivity of at least 50% in a wavelength range of at least 800 nm to 1300 nm, and preferably 700 nm to 2500 nm, and more preferably 700 nm to 3000 nm.

[0205] Exemplary infrared reflective layers include infrared reflective multilayer films, such as those described above in the section on UV reflective multilayer films, except that they are tuned to infrared wavelengths. For multilayer optical films involving visible and near-infrared wavelengths, a quarter-wavelength stack design results in each of the layers 312, 314 in the multilayer stack (see...). Figure 3 It has an average thickness of no more than about 0.7 micrometers.

[0206] Multilayer optical films (including reflective polarizers and mirrors), such as those described in the following, can be prepared by co-extruding alternating polymer layers with different refractive indices: U.S. Patent Nos. 6,045,894 (Jonza et al.); 6,368,699 (Gilbert et al.); 6,531,230 (Weber et al.); 6,667,095 (Wheatley et al.); 6,783,349 (Neavin et al.); 7,271,951B2 (Weber et al.); 7,632,568 (Padiyath et al.); and 7,952,805 (McGurran et al.); and PCT Publications WO 95 / 17303 (Ouderkirk et al.) and WO 99 / 39224 (Ouderkirk et al.).

[0207] An exemplary IR reflective layer also includes: a metal layer, such as aluminum, gold or silver; and a layer of metal oxide or metal sulfide, such as cerium oxide, aluminum oxide, magnesium oxide and indium tin oxide.

[0208] Other IR reflective layers known in the art may also be used.

[0209] Degassing adhesive layer

[0210] Radiation-cooled articles optionally include a degassing adhesive layer disposed adjacent to a white diffuse-reflective microporous layer and opposite to a non-white colored reflective film. Adhesives that allow air (or other fluids) to be isolated between the adhesive layer and the substrate are well known in the art.

[0211] For example, microstructured adhesive articles have been prepared by applying a flowable pressure-sensitive adhesive to the surface of a microstructured release liner or a microstructured molding tool. This process results in the formation of an adhesive with a microstructured surface. When the resulting article is dry-laminated under pressure to a substrate such as a glass or polymer film, the microstructure features generated in the adhesive surface allow air to escape from the bonding interface, thereby minimizing or preventing the formation of bubbles and pores.

[0212] During lamination, microstructural features can flatten and wet the substrate surface. Typically, the applied pressure is used to cause the structure to collapse during lamination and form an adhesive bond. However, as the adhesive relaxes and attempts to return to its initial microstructured state, this process introduces stress into the adhesive. These stresses can create defects in the adhesive that adversely affect its adhesive and optical properties.

[0213] Various techniques have been used to prepare adhesive articles with microstructured surfaces. Typically, the adhesive surface comes into contact with a structuring tool or spacer to form a structured pattern within the adhesive layer. For example, in U.S. Patent No. 6,315,651 (Mazurek et al.), a microstructured pressure-sensitive adhesive is formed by molding the adhesive layer against a microstructured tool or spacer, and in U.S. Patent Publication No. 2006 / 0188704 (Mikami et al.), a fluid outlet structure is formed in the adhesive surface by contacting the adhesive with a structuring spacer or spacer. Japanese Utility Model Publication 7-29569 (Kawada et al.) describes the formation of an adhesive label for containers such as bottles. The adhesive label can be easily removed from the bottle surface by immersing the bottle in an aqueous solution because the adhesive contains non-uniform shapes to form permeation channels that allow fluid to enter the adhesive lines. The label is formed by contacting the adhesive with a structuring spacer, and then contacting the label material with the exposed adhesive surface, the spacer having been formed by embossing. Additionally, in U.S. Patent Publication No. 2007 / 0212635 (Sherman et al.), a structured adhesive surface is formed by pressing a microstructured tool or isolation liner onto the crosslinked adhesive surface.

[0214] Another embodiment of the temporary morphology formed on the adhesive surface is disclosed in U.S. Patent No. 5,268,228 (Orr). The double-sided adhesive-coated tape has fine grooves on one or both sides of the tape to facilitate air venting, thereby minimizing non-contact areas. The grooves on the tape are fine enough that they largely or completely disappear once the two surfaces to be bonded are in place. Example 1 describes scribing through a protective sheet with the grooves positioned 70 to 150 micrometers below the adhesive surface.

[0215] In Japanese Patent Publication 7-138541 (Shimizu), the adhesive process film is prepared using an imprinting process to form fine, continuous grooves.

[0216] In addition, several applications have been described in which the microstructured adhesive layer has beads or plugs protruding from the adhesive surface to allow the adhesive surface to be positioned or repositioned upon contact with a substrate surface. U.S. Patent No. 5,296,277 (Wilson et al.) describes such a system. U.S. Patent No. 7,060,351 (Hannington) describes an adhesive article that provides an air outlet by providing areas without initial adhesive force for air to flow out from under the structure. In the article, a continuous adhesive layer adheres to a surface having multiple spatially spaced non-adhesive materials, and the non-adhesive materials become embedded in the adhesive layer.

[0217] Representative embodiments of patents describing how the morphology of the adhesive is constructed from the interface between the adhesive and the release liner include U.S. Patents 5,296,277 and 5,362,516 (both by Wilson et al.) and 5,141,790 (by Calhoun et al.). The primary morphological feature in the adhesive surface is a protrusion separated from the adhesive surface having a defined contact area.

[0218] Examples of temporary morphologies formed on the adhesive surface are disclosed in U.S. Patent Nos. 5,344,681 and 5,449,540 (both by Calhoun et al.). Segmented pressure-sensitive adhesive transfer tapes are designed to prevent lateral flow of the adhesive before transfer, but allow flow after transfer to form a continuous adhesive bond. Small adhesive segments have a controllable thickness. The adhesive transfer tape comprises: a carrier having two opposing surfaces, one surface containing a series of grooves, and the other surface being relatively smooth; pressure-sensitive adhesive present in the grooves surrounded by unadhesive areas, such that when the tape is wound around itself with the surfaces in contact and then unwound, the adhesive is transferred from one surface to the other. Preferably, the grooves are formed by embossing and are spaced apart. Preferably, the cross-section of the recesses is elliptical, circular, polygonal, or rectangular. Preferably, the adhesive is pressure-sensitive to acrylic or rubber resin.

[0219] Any of the adhesive layers described above can be used in radiation-cooled products.

[0220] Multi-surface passive cooling products

[0221] In a third aspect, this disclosure provides a multi-surface passive cooling article. For example, a radiation-cooled article may optionally be combined with a multi-surface passive cooling layer (e.g., disposed adjacent to the main surface of a white diffuse microporous layer and opposite to a non-white colored reflective film) to provide a multi-surface passive cooling article. The multi-surface passive cooling article includes:

[0222] A plurality of first elements defining the outer surface of a first element, the plurality of first elements defining a first absorbance greater than or equal to 0.6 in the atmospheric window wavelength range of 8 micrometers to 13 micrometers, and a first average reflectance greater than or equal to 80% in the solar wavelength range of 0.4 micrometers to 2.5 micrometers; wherein at least one of the first elements includes a radiation cooling layer comprising: a) a white diffuse reflective microporous layer having a solar-weighted reflectance of 0.8 or greater, 0.85, 0.9 or 0.95 or greater for vertically incident electromagnetic radiation with a majority of wavelengths in the range of 350 nanometers (nm) to 2500 nm; and b) a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse reflective microporous layer, wherein the non-white colored reflective film reflects at least 30 nm of wavelength bandwidth in the wavelength range of 350 nm to 700 nm; and

[0223] A plurality of second elements defining the outer surface of the second element, the plurality of second elements defining a second absorbance of less than or equal to 0.5 in the atmospheric window wavelength range, and defining a second average reflectance of greater than or equal to 60% in the solar wavelength range;

[0224] The plurality of first elements and the plurality of second elements are dispersed to form a main structure, the main structure having a first main surface including the outer surfaces of the first elements and the outer surfaces of the second elements, and a second main surface opposite to the first main surface;

[0225] The main structure has a first end region and a second end region, wherein the outer surface of the first element faces a first direction toward the first end region, and the outer surface of the second element faces a second direction toward the second end region.

[0226] In some applications, the main structure is suitable for the vertical surface of the substrate (such as a building or vehicle), where high emissivity elements face the sky or are oriented upward toward the sky, while low emissivity elements face the ground or are oriented downward toward the ground, or are at least “shielded” by the high emissivity elements.

[0227] Figure 16 The following graphs are: solar energy (or sunlight) energy spectrum 202, describing the ground reference spectrum present in ASTM G173-03 (2012); energy transmittance % spectrum 204 (e.g., 0 to 1) in the atmospheric window region; and high emissivity elements of the article (such as the first element 122). Figure 14 ) or first element 182 ( Figure 15An embodiment of absorption 206 (e.g., absorbance or emissivity, as shown on the y-axis from 0 to 1). Absorption 206 can also be described in terms of absorbance (e.g., the logarithm of transmittance).

[0228] A high emissivity element may define a reflector to reflect some or all of the light in the energy spectrum 202 of the reflection band 208. The reflection band 208 at least partially (or completely) covers wavelengths in the solar region, and in some cases (such as infrared mirror films), at least partially (or completely) covers wavelengths in the visible, near-infrared, or mid-infrared regions. The reflector may have low absorption 206 in the reflection band 208. The high emissivity element may have high absorption 206 in the absorption band 211. The absorption band 211 may at least partially (or completely) cover wavelengths in the atmospheric window region, which may facilitate the transmission of at least some infrared energy through the high-transmittance regions of the atmosphere (e.g., from any article of this disclosure), as shown, for example, as in the energy transmittance % spectrum 204. The high emissivity element may have low reflectivity in the absorption band 211.

[0229] Figure 14 This is a schematic cross-sectional view of one embodiment of a multi-surface passive cooling article 125. Article 125 can be coupled to the outer surface of a substrate 1210. Figure 12A The view shown illustrates a cross-section of a multi-surface passive cooling article 125 along a plane orthogonal to at least a portion of the outer surface of a substrate 1210. In some embodiments, the substrate 1210 is coupled to a fluid, liquid, or gas that can transfer heat from another article, such as a heat exchanger, building, battery, refrigerator, freezer, air conditioner, or photovoltaic module. As shown, the multi-surface passive cooling article 125 includes a plurality of first elements 122 defining a first element outer surface 126 and a plurality of second elements 124 defining a second element outer surface 128. Each first element 122 may define a first element outer surface 126. Each second element 124 may define a second element outer surface 128. Generally, each first element 122 may be positioned close to or adjacent to one of the second elements 124, or vice versa. The plurality of first elements 122 and the plurality of second elements 124 may be distributed to form a first main surface 130 of a main structure (which may typically be formed as a sheet with an uneven main surface). Therefore, multi-surface passive cooling products are usually formed from more than a single layer.

[0230] The first main surface 130 includes a first element outer surface 126 and a second element outer surface 128. The first main surface 130 may be continuously formed from the first element 122 and the second element 124. The second main surface 132 may be defined opposite to the first main surface 130. Specifically, the second main surface 132 may be on the side of the article 120 opposite to the first main surface 130.

[0231] The multi-surface passive cooling article 125 may include a backing layer 160 coupling to a substrate 1210. The backing layer 160 may be defined to be coupled to, or may be defined to form, at least partially (or completely) a second main surface 132 formed by a plurality of first elements 122 and second elements 124. The multi-surface passive cooling article 125 may define a first end region 134 and a second end region 136. The outer surface 126 of the first elements may face a first direction toward the first end region 134. The surface of the second elements may face a second direction toward the second end region 136. In use, the multi-surface passive cooling article 125 may be oriented such that the first end region 134 is closer to the sky and the second end region 136 is closer to the ground. The outer surface 126 of the first elements may be described as a surface facing the sky. The outer surface 128 of the second elements may be described as a surface facing the ground.

[0232] The plurality of first elements 122 and the plurality of second elements 124 can be formed in any suitable shape to provide a first element outer surface 126 and a second element outer surface 128 in a suitable orientation. For example, relative to Figures 4A to 11 or Figures 13A to 13E Any shape described may be used to form one or more of the elements 122, 124. In some embodiments, at least some (or all) of the elements 122, 124 are formed as a continuous surface structure. As used herein, the term "continuous surface structure" refers to a surface structure that extends completely across the first main surface 130 in at least one direction (such as a vertical or horizontal direction). In one or more embodiments, at least some (or all) of the elements 122, 124 are formed or arranged as alternating rows of elongated elements. In one embodiment, each element 122, 124 may extend horizontally from a first side of the multi-surface passive cooling article 125 to a second side opposite to the first side, for example, along a horizontal direction orthogonal to the vertical direction, which is defined as aligned with the direction between the first end region 134 and the second end region 136. A plurality of elements 122, 124 may be vertically dispersed, for example, in a linear array. Any suitable shape may be used to form the elements 122, 124 as alternating rows or elongated elements, such as those resembling... Figures 4A to 8 Those shown. Specifically, the first element 122 can be used to form Figures 4A to 8 A portion of each structure shown (e.g., the portion closer to the first end region 134), and a second element 124 may be used to form another portion of each structure (e.g., the portion closer to the second end region 136).

[0233] In some implementation schemes (such as) Figure 14In an exemplary embodiment, the multi-surface passive cooling article 125 can be described as having a plurality of first elements 122 and a plurality of second elements 124 separated by a plurality of parallel ridges. In some embodiments, the multi-surface passive cooling article 125 can be described as having a plurality of parallel ridges, each ridge having a first ridge surface and a second ridge surface facing away from each other, corresponding to the first element 122 and the second element 124, respectively.

[0234] In some embodiments, at least some (or all) of elements 122, 124 are formed as discrete surface structures. As used herein, the term "discrete surface structure" refers to a surface structure that does not fully extend across the first main surface 130 in a vertical or horizontal direction. In some embodiments, elements 122, 124 may be vertically and horizontally distributed (e.g., in a two-dimensional array). Elements 122, 124 can be formed as discrete surface structures using any suitable shape, for example, similar to Figures 9 to 11 and Figures 13A to 13E The shape shown is indicated. In some embodiments, the discrete surface structure may have any suitable three-dimensional shape, such as a hemisphere, a semi-oval, a semi-oblong, a semi-flattened sphere, or a pyramidal shape. In some embodiments, the discrete surface structure defines surfaces 126, 128 (e.g., when viewed perpendicularly to the first primary surface 130) in the shape of a rectangle, square, circle, ellipse, triangle, or other suitable geometry.

[0235] Generally, the cross-sectional profiles of one or more elements 122, 124 may have a cross-sectional profile shape (e.g., viewed in a horizontal direction or in a direction parallel to the main surfaces 130, 132), for example, generally resembling or similar to a quarter circle, a quarter ellipse, a triangle, a square, a rectangle, multiples thereof, or combinations thereof, or providing another suitable geometry for the first main surface 130. The cross-sections of elements 122, 124 may be identical or similar. In one embodiment, the cross-sections of a first element 122 and an adjacent second element 124 may each be generally formed as one or more rectangular shapes (see...). Figure 14 These rectangular shapes intersect at an angle to form a first main surface 130. In another embodiment, the cross-section of a first element 122 and an adjacent second element 124 may each be approximately formed as a quarter circle (see [link to previous embodiment]). Figure 15 The elements 122 and 124 may intersect to form a semicircle. The cross-sections of elements 122 and 124 may also be different. In another embodiment, the cross-section of a first element 122 may be formed as a right-angled triangle, and the cross-section of an adjacent second element 124 may be formed as a quarter-circle, together forming a triangular shape with a curved side. In some embodiments, at least some of the outer surfaces 126 of the first element or 128 of the second element define generally planar surfaces (see...). Figure 14In some embodiments, at least some of the outer surfaces 126 of the first element or 128 of the second element define curved surfaces (see [link]). Figure 15 ).

[0236] In some embodiments, as shown, for example in at least one cross-sectional view, the support layer 138 may define a surface profile having the same contour as the first main surface 130 (e.g., a surface facing elements 122, 124). In some embodiments, at least some of the plurality of first elements 122 or second elements 124 define generally planar element outer surfaces 126, 128 applied to the contoured surface of the support layer 138, the support layer at least partially (or completely) defining an angle between the element outer surfaces 126, 128. One or more angles may be used to define the relative orientation of the first element outer surfaces 126 and the second element outer surfaces 128 relative to each other. In some embodiments, a normal vector may be used to facilitate defining such angles. A normal vector may be defined as normal (or orthogonal or perpendicular) to a particular surface. As used herein, the term "normal" when referring to a vector means a line perpendicular to at least a portion of a particular surface or a line perpendicular to the average tangent of a particular surface.

[0237] In some embodiments, a first vector 148 is defined perpendicular to the outer surface 126 of the first element. A second vector 150 may be defined perpendicular to the surface 128 of the second element. At least one of the first vectors 148 and at least one of the second vectors 150 may define an inter-element angle 152 between them. In some embodiments, the inter-element angle 152 is greater than or equal to 15 degrees and less than or equal to 165 degrees (in some embodiments, greater than or equal to 45 degrees, 60 degrees, 90 degrees, or even 120 degrees, or less than or equal to 135 degrees, 120 degrees, 90 degrees, or even 60 degrees). The first vector 148 of the outer surface 126 of the first element may also be defined relative to a master surface vector 154. In some embodiments, a master surface vector 154 may be defined perpendicular to the second master surface 132 of the multi-surface passive cooling article 125. At least one of the first vector 148 and the master surface vector 154 may define a first element angle 156 between them. In some embodiments, the first element angle 156 is greater than or equal to 15 degrees (or greater than or equal to 45 degrees, 60 degrees, or even 75 degrees) and less than or equal to 75 degrees (or less than or equal to 65 degrees or even 50 degrees). The second vector 150 of the outer surface 128 of the second element may also be defined relative to the main surface vector 154. At least one of the second vector 150 and the main surface vector 154 may define the second element angle 158 between them. In some embodiments, the second element angle 158 is greater than or equal to 15 degrees (or greater than or equal to 30 degrees or even 45 degrees) and less than or equal to 75 degrees (or less than or equal to 45 degrees or even 30 degrees).

[0238] Various suitable materials and structures can be used to form at least some (or all) of the first element 122. Non-limiting embodiments of materials and structures that can be used to form the first element 122 include: a radiation-cooled article as described in detail above with respect to the first aspect; a dense fluoropolymer layer; a microporous (or microvoid) fluoropolymer layer; a dense polyester layer at least partially (or completely) covered by a dense fluoropolymer layer; a microporous (or microvoid) polyester layer at least partially (or completely) covered by a dense fluoropolymer layer; a multilayer optical film with high average reflectivity that at least partially (or completely) defines a solar wavelength range; and a metallic layer with high average reflectivity that at least partially (or completely) defines a solar wavelength range.

[0239] In some embodiments, at least some (or all) of the plurality of first elements 122 may include inorganic particles with high average reflectivity that at least partially (or completely) define the solar energy region. In particular, the inorganic particles may be or include white inorganic particles. Various types of inorganic particles, fluoropolymers, microporous (or microvoid) polymer layers, multilayer optical films (such as solar mirror films), and metal layers are further described herein.

[0240] Various suitable materials and structures can be used to form at least some (or all) of the second element 124. Non-limiting embodiments of materials and structures that can be used to form the second element 124 include: a dense polyethylene layer, a dense polyethylene copolymer layer, a microporous (or microvoid) polyethylene layer, a microporous (or microvoid) polyethylene copolymer layer, a fluoropolymer layer defining a thickness of less than or equal to 10 micrometers, a coating including metal, an infrared mirror film with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range, a patterned layer with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range, a patterned layer at least partially (or completely) covered by an infrared mirror film with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range, and a metallic layer with high average reflectivity defined at least partially (or completely) within the solar wavelength range. One commercially available material that can be used to form the second element 124 (or 128) is a film sold by 3M under the trade name “3M THINSULATE Window Film ClimateControl 75”.

[0241] This article further describes various types of polyethylene copolymers, including metallic coatings, infrared mirror films (such as low-emissivity infrared mirror films), and patterned layers.

[0242] Various suitable materials and structures can be used to form at least some (or all) of the first outer layers 144 of the plurality of first elements 122, at least partially (or completely). Non-limiting embodiments of materials and structures that can be used to form the first outer layers 144 include: radiation-cooled articles as described in detail above with respect to the first aspect, dense fluoropolymer layers, microporous (or microvoid) fluoropolymer layers, dense polyester layers at least partially (or completely) covered by dense fluoropolymer layers, microporous (or microvoid) polyester layers at least partially (or completely) covered by dense fluoropolymer layers, and multilayer optical films with high average reflectivity that at least partially (or completely) define a solar wavelength range.

[0243] Various suitable materials and structures can be used to form at least some (or all) of the second outer layer 146. Non-limiting embodiments of materials and structures that can be used to form the second outer layer 146 include: a dense polyethylene layer, a dense polyethylene copolymer layer, a microporous (or microvoid) polyethylene layer, a microporous (or microvoid) polyethylene copolymer layer, a fluoropolymer layer defining a thickness of less than or equal to 10 micrometers, a coating including metal, an infrared mirror film with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range, and a patterned layer with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range, a patterned layer at least partially (or completely) covered by an infrared mirror film with low absorbance defined at least partially (or completely) within the atmospheric window wavelength range.

[0244] Various suitable materials and structures can be used to form at least some (or all) of the support layer 138, the first support layer 140, or the second support layer 142, at least partially (or completely). Non-limiting embodiments of materials and structures that can be used to form the support layer 138, the first support layer 140, or the second support layer 142 include: metal layers and polymer layers. Non-limiting examples of materials and structures that can be used to form polymer layers include: dense polymer layers, microporous (or microvoid) polymer layers that at least partially (or completely) define high average reflectivity within a solar wavelength range, multilayer optical films that at least partially (or completely) define high average reflectivity within a solar wavelength range, and patterned layers.

[0245] Various suitable materials and structures can be used to at least partially (or completely) define the high absorbance of the plurality of first elements 122 in the atmospheric window region. Non-limiting embodiments of materials and structures that can be used to at least partially (or completely) define the high absorbance in the atmospheric window region include: radiation-cooled articles as described in detail above with respect to the first aspect, dense fluoropolymer layers, microporous (or microvoid) fluoropolymer layers, dense polyester layers at least partially (or completely) covered by dense fluoropolymer layers, microporous (or microvoid) polyester layers at least partially (or completely) covered by dense fluoropolymer layers, and multilayer optical films.

[0246] In some embodiments, at least some (or all) of the first elements 122 may include various structures that can contribute to high absorbance in the atmospheric window region. In some embodiments, inorganic particles may be provided as a surface or embedded structure on or within the material of the plurality of first elements 122, such as embedded in any polymer layer (such as a dense polymer layer, a microporous (or microvoid) polymer layer, or a multilayer optical film) to contribute to high absorbance in the atmospheric window region. In some embodiments, the inorganic particles may be or include white inorganic particles that can at least partially (or completely) define a high average reflectance in the solar region. Any suitable white inorganic particles known to those skilled in the art that benefit from this disclosure may be used. The inorganic particles may include those described above regarding Figures 13A to 13E Those that were discussed.

[0247] Various suitable materials and structures can be used to at least partially (or completely) define the low absorbance of the plurality of second elements 124 in the atmospheric window region. Non-limiting examples of materials and structures that can be used to at least partially (or completely) define the low absorbance in the atmospheric window region include: a dense polyethylene layer, a dense polyethylene copolymer layer, a microporous (or microvoid) polyethylene layer, a microporous (or microvoid) polyethylene copolymer layer, a fluoropolymer layer defining a thickness of less than or equal to 10 micrometers, a coating containing metal, an infrared mirror film that at least partially (or completely) defines the low absorbance in the atmospheric window wavelength range, a patterned layer, and a patterned layer that is at least partially (or completely) covered by an infrared mirror film.

[0248] Various suitable materials and structures can be used to at least partially (or completely) define the high average reflectivity of a plurality of first elements 122 or second elements 124 in a solar region. Non-limiting embodiments of materials and structures that can be used to at least partially (or completely) define the high average reflectivity in a solar region include: radiation-cooled articles as described in detail above with respect to the first aspect; metallic layers that at least partially (or completely) define the high average reflectivity in a solar wavelength range; microporous (or microvoid) polymer layers; and multilayer optical films. In some embodiments, one or more structures also include white inorganic particles, such as any polymer layer or multilayer optical film, which at least partially (or completely) define the high average reflectivity in a solar region.

[0249] The first primary surface 130 can be described as a textured surface. Some textures (e.g., depending on the dimensions of various surface structures relative to the wavelength of electromagnetic radiation) can enhance the passive cooling effect achieved by the multi-surface passive cooling article 125 as a whole. While one purpose of texturing the first primary surface 130 to include surface structures may be to provide radiative cooling, texturing can also provide additional benefits such as resistance or stain resistance. Various types of surface structures can include surface microstructures or surface nanostructures, which can be discrete or continuous.

[0250] In some embodiments, at least some of the plurality of first elements 122 or second elements 124 may define various drag-resistant surface structures to provide a reduction in drag resistance, for example when used on vehicle surfaces. For example, texturing can achieve drag reduction when a vehicle moves through air. The presence of surface microstructures or nanostructures can lead to a reduction in the coefficient of friction between the surface and the air through which the vehicle moves, which can result in cost or fuel savings. Any suitable shape can be used to form the drag-resistant surface structure, for example, similar to... Figures 9 to 11 and Figures 13A to 13E The shape shown.

[0251] In some embodiments, at least some of the plurality of first elements 122 or second elements 124 may define various antifouling surface structures that may contribute to antifouling and anti-fouling properties. In some embodiments, antifouling surface structures may be defined on or above at least some of the first outer surface 126 or the second outer surface 128 to contribute to antifouling and anti-fouling properties. Specifically, in some embodiments, at least the first outer surface 126 (which is more susceptible to dirt and grime than the second outer surface 128) may include antifouling surface structures. Figures 4A to 11 and Figures 13A to 13E Non-limiting embodiments of anti-fouling surface structures with anti-fouling properties are shown, and the anti-fouling layer has been discussed in detail above.

[0252] Any suitable fluoropolymer material can be used in the multi-surface passive cooling article 125. Non-limiting examples of fluoropolymers that can be used include those discussed in detail above with respect to the protective layer.

[0253] Any suitable microporous (or microvoid) polymer layer (or film) can be used, for example, as discussed above regarding white diffuse reflective layers.

[0254] Figure 15 This is a schematic cross-sectional view of another embodiment of the multi-surface passive cooling article 180. A plurality of first elements 182 and a plurality of second elements 184 may each include structures or materials that respectively provide reflectivity and high or low absorbance and emissivity. Specifically, the plurality of first elements 182 may provide high absorbance in the atmospheric window region and high reflectivity in the solar region, and the plurality of second elements 184 may provide low absorbance in the atmospheric window region and high reflectivity in the solar region. Any suitable material may be used to form article 180, such as the same or similar material used to form multi-surface passive cooling article 125. Curved outer surfaces 186 of the first elements and 188 of the second elements are also shown, which may also be used as… Figure 14 The corresponding first element outer surface 126 or second element outer surface 128. In the illustrated embodiment, the cross-sectional profile of each of the first element outer surface 186 or the second element outer surface 188 has a quarter-circle shape. In some embodiments, the shape of the multi-surface passive cooling article 125 is advantageous because it can be easily used with half (or the entire) of a pipe for transporting fluid, thereby cooling the fluid within the pipe structure.

[0255] The first vector 190 may be defined perpendicular to the outer surface 186 of the first element. The second vector 192 may be defined perpendicular to the outer surface 188 of the second element. As shown, the first vector 190 and the second vector 192 are defined as being perpendicular to at least a portion of the respective outer surfaces 186, 188 or perpendicular to the average tangent of the respective outer surfaces 186, 188.

[0256] Figure 17 yes Figure 14A schematic diagram of one embodiment of a multi-surface passive cooling article 125. In the illustrated embodiment, article 1120 includes a plurality of first elements 1122 and a plurality of second elements 1124. The plurality of first elements 1122 include a first support layer 1126 and a first outer layer 1128 that at least partially or completely covers the respective first support layer. The plurality of second elements 1124 include a second support layer 1130 and a second outer layer 1132 that at least partially or completely covers the respective second support layer. The first outer layer 1128 may include a radiative cooling article and at least partially or completely defines a high average reflectivity in a solar region and a high absorbance in an atmospheric window region. The second outer layer 1132 may be at least partially formed of or include microporous polyethylene, which may be microporous polyethylene, to at least partially or completely define a high average reflectivity in a solar region and a low absorbance in an atmospheric window region. The first support layer 1126 and the second support layer 1130 may be formed of metal such that they are metal substrates.

[0257] In any embodiment, the multi-surface passive cooling article includes one or more optional transparent adhesive bonding layers to bond any components / structures to each other as needed. Suitable transparent adhesive bonding layers are described in detail above regarding radiative cooling articles.

[0258] Further details regarding suitable multi-surface passive cooling layers are described in co-owned U.S. Patent Application Serial No. 62 / 955,800 (Hebrink et al.), entitled “Multi-Surface Passive Cooling Articles,” which is incorporated herein by reference in its entirety.

[0259] Exemplary Implementation

[0260] In a first embodiment, this disclosure provides a radiation-cooled article. The radiation-cooled article includes: a) a white diffuse-reflective microporous layer; and b) a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers. The white diffuse-reflective microporous layer has a solar-weighted reflectivity of 0.8 or greater, 0.85, 0.9, or 0.95 or greater for vertically incident electromagnetic radiation with most wavelengths in the range of 350 nanometers (nm) to 2500 nm. The non-white colored reflective film is disposed adjacent to the main surface of the white diffuse-reflective microporous layer and reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm.

[0261] In a second embodiment, this disclosure provides a radiation-cooled article according to the first embodiment, wherein the white diffuse-reflective microporous layer comprises a microporous membrane.

[0262] In a third embodiment, this disclosure provides a radiation-cooled article according to a first or second embodiment, wherein the white diffuse-reflective microporous layer comprises polyester or a polyester copolymer.

[0263] In a fourth embodiment, this disclosure provides a radiation cooling article according to any one of the first to third embodiments, wherein the white diffuse reflective microporous layer comprises at least one of polyethylene, polypropylene, polysaccharide, fluoropolymer or fluoropolymer copolymer.

[0264] In a fifth embodiment, this disclosure provides a radiation cooling article according to any one of the first to fourth embodiments, wherein the white diffuse reflective microporous layer comprises white inorganic particles.

[0265] In a sixth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to fifth embodiments, wherein the white diffuse-reflective microporous layer comprises aromatic polyester particles.

[0266] In a seventh embodiment, this disclosure provides a radiation-cooled article according to any one of the first to sixth embodiments, wherein the non-white colored reflective film comprises a multilayer optical film comprising alternating layers of polyethylene terephthalate (PET) and methyl methacrylate copolymer (coPMMA).

[0267] In the eighth embodiment, this disclosure provides a radiation cooling article according to any one of the first to seventh embodiments, wherein the non-white color reflective film comprises a multilayer optical film comprising alternating layers of PET and fluoropolymer.

[0268] In the ninth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to eighth embodiments, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 600 nm to 700 nm.

[0269] In a tenth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to eighth embodiments, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 400 nm to 500 nm.

[0270] In the eleventh embodiment, this disclosure provides a radiation-cooled article according to any one of the first to eighth embodiments, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 500 nm to 600 nm.

[0271] In the twelfth embodiment, this disclosure provides a radiation cooling article according to any one of the first to eleventh embodiments, wherein the non-white colored reflector also reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 700 nm to 2000 nm.

[0272] In the thirteenth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to twelfth embodiments, further comprising one or more markings present on the main surface of at least one of the white diffuse microporous layer or the non-white colored reflective film.

[0273] In the fourteenth embodiment, this disclosure provides a radiation-cooled article according to the thirteenth embodiment, wherein the one or more markings comprise at least one infrared-reflective pigment.

[0274] In the fifteenth embodiment, this disclosure provides a radiation cooling article according to any one of the first to fourteenth embodiments, further comprising a hard coating or film layer disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer, wherein the hard coating or film layer is an outer layer.

[0275] In a sixteenth embodiment, this disclosure provides a radiation cooling article according to any one of the first to fourteenth embodiments, further comprising a protective layer containing a fluoropolymer, the protective layer being disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse reflective microporous layer, wherein the protective layer is an outer layer.

[0276] In the seventeenth embodiment, this disclosure provides a radiation cooling article according to the sixteenth embodiment, wherein the protective layer includes a surface structure.

[0277] In the eighteenth embodiment, this disclosure provides a radiation cooling article according to any one of the first to fourteenth embodiments, further comprising an antifouling layer disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer, wherein the antifouling layer is an outer layer.

[0278] In a nineteenth embodiment, this disclosure provides a radiation-cooled article according to an eighteenth embodiment, wherein the antifouling layer includes an outwardly facing antifouling surface extending along an axis, wherein a plane containing the axis defines a cross-section of the layer and intersects the surface to define a line describing the surface in two dimensions. The layer includes: a) a series of microstructures at least partially defined by the line, the line defining a series of alternating micropeaks and microspaces along the axis, wherein 1) the boundary between each adjacent micropeak and microspace includes at least one of a bend or inflection point of the line; or 2) each microspace includes a maximum absolute slope defining an angle of up to 30 degrees from the axis, wherein each micropeak includes a first microsegment defining a first average slope and a second microsegment defining a second average slope, and wherein the angle formed between the first average slope and the second average slope is up to 120 degrees. The layer also includes b) a plurality of nanostructures at least partially defined by the line, the line defining at least a series of nanopeaks disposed along the axis in at least a microspace, wherein each nanopeak has a height and the height of each corresponding micropeak is at least 10 times the height of the nanopeak.

[0279] In the twentieth embodiment, this disclosure provides a radiation cooling article according to any one of the fifteenth to nineteenth embodiments, wherein the hard coating or film layer, the protective layer or the antifouling layer comprises ceramic or glass beads, ceramic or glass bubbles, or combinations thereof.

[0280] In the twenty-first embodiment, this disclosure provides a radiation cooling article according to any one of the first to twenty embodiments, further comprising an infrared reflective layer disposed between the white diffuse reflective microporous layer and the non-white colored reflective film, or adjacent to the non-white colored reflective film and opposite to the white diffuse reflective microporous layer, wherein the infrared reflective layer has an average reflectivity of at least 50% in the wavelength range of 700 nm to 2000 nm.

[0281] In the twenty-second embodiment, this disclosure provides a radiation cooling article according to any one of the first to twenty-first embodiments, further comprising an ultraviolet-reflective multilayer optical film disposed adjacent to the non-white colored reflective mirror film and opposite to the white diffuse reflective microporous layer, wherein the ultraviolet-reflective multilayer optical film has a reflectivity of at least 50% for most ultraviolet radiation in the range of at least 340 nm but less than 400 nm.

[0282] In the twenty-third embodiment, this disclosure provides a radiation cooling article according to any one of the first to twenty-second embodiments, further comprising a transparent adhesive bonding layer disposed between the white diffuse reflection microporous layer and the non-white colored reflective film.

[0283] In the twenty-fourth embodiment, this disclosure provides a radiation cooling article according to any one of the first to twenty-third embodiments, further comprising a degassing adhesive disposed adjacent to the white diffuse microporous layer and opposite to the non-white colored reflective film.

[0284] In the twenty-fifth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to twenty-fourth embodiments, the radiation-cooled article having an average electromagnetic radiation absorbance of at least 0.80 in a wavelength range of 8 micrometers to 13 micrometers.

[0285] In the twenty-sixth embodiment, this disclosure provides a radiation-cooled article according to any one of the first to twenty-fifth embodiments, which exhibits passive radiation cooling to below ambient temperature under direct sunlight.

[0286] In a twenty-seventh embodiment, this disclosure provides a composite cooling system. The composite cooling system includes a radiant cooling article attached to a vehicle or trailer according to any one of the first to twenty-sixth embodiments.

[0287] In a twenty-eighth embodiment, this disclosure provides a multi-surface passive cooling article. The multi-surface passive cooling article includes a plurality of first elements defining an outer surface of a first element, the plurality of first elements defining a first absorbance greater than or equal to 0.6 in an atmospheric window wavelength range of 8 to 13 micrometers, and a first average reflectance greater than or equal to 80% in a solar wavelength range of 0.4 to 2.5 micrometers. At least one of these first elements includes a radiative cooling layer comprising: a) a white diffuse microporous layer having a solar-weighted reflectivity of 0.8 or greater, 0.85, 0.9, or 0.95 or greater for vertically incident electromagnetic radiation in the wavelength range of 350 nm to 2500 nm; and b) a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse microporous layer, wherein the non-white colored reflective film reflects at least a wavelength bandwidth of 30 nm in the wavelength range of 350 nm to 700 nm. The multi-surface passive cooling article also includes a plurality of second elements defining the outer surface of the second elements, the plurality of second elements defining a second absorbance of less than or equal to 0.5 in the atmospheric window wavelength range and a second average reflectivity of greater than or equal to 60% in the solar wavelength range. The plurality of first elements and the plurality of second elements are dispersed to form a main structure, the main structure having a first main surface including the outer surfaces of the first elements and the outer surfaces of the second elements, and a second main surface opposite to the first main surface. The main structure has a first end region and a second end region, wherein the outer surfaces of the first elements face a first direction toward the first end region, and the outer surfaces of the second elements face a second direction toward the second end region.

[0288] In the twenty-ninth embodiment, this disclosure provides a multi-surface passive cooling article according to the twenty-eighth embodiment, wherein the radiation cooling article is any one of the second to twenty-sixth embodiments.

[0289] The following examples further illustrate the advantages and embodiments of the present invention; however, the specific materials and quantities mentioned in these examples, as well as other conditions and details, should not be construed as undue limitation of the invention. Unless otherwise specified, all parts and percentages are by weight.

[0290] Example

[0291] Example 1

[0292] A red reflective (590nm to 795nm) film (trade name "3M DICHROIC GLASS FINISHDF-PA BLAZE" from 3M Corporation, St. Paul, Minnesota) was laminated onto a 188-micron-thick microporous PET film (trade name "LUMIRROR XJSA2" from Toray Plastics (USA) Corporation, North Kingston, Rhode Island) using an optically clear adhesive (trade name "3M OCA 8171" from 3M Corporation, St. Paul, Minnesota).

[0293] A red reflective microporous composite film was then laminated onto an aluminum plate with a thermistor temperature data logger embedded in its surface (available under the trade name "HOBO MX2303" from Onset Computer Corporation, Bourne, MA) and bonded with an aluminum backing strip (available under the trade name "3M ALUMINUM FOIL TAPE 425" from 3M Corporation, St. Paul, Minnesota) to create the radiant cooling plate RCP1. A one-inch (2.54 cm) thick layer of polystyrene foam insulation was placed beneath the aluminum contrast radiant cooling plate RCP1 to thermally insulate it from the ground. Another HOBO MX2303 thermistor temperature data logger was used to measure the ambient air temperature near RCP1. Ambient air temperature and RCP1 temperature were continuously measured for 100 hours (hr), with the thermocouple data logger recording the temperature every minute. The ambient air temperature and RCP1 temperature recorded per minute are averages of 100 hours or 6000 data points. The average ambient air temperature was measured to be 21.5℃. For a sub-ambient cooling difference of -2.1℃, the average RCP1 temperature was measured to be 19.4℃.

[0294] Example 2

[0295] A red reflective and near-IR reflective (650nm to 1350nm) film (3M COOL MIRROR FILM 330, 3M Inc., St. Paul, Minnesota) was laminated onto a 188-micron-thick microporous PET film (Toray Plastics (USA) Inc., North Kingston, Rhode Island, 3M Inc., 3M OCA 8171, 3M Inc., St. Paul, Minnesota ...

[0296] A red reflective microporous composite film was then laminated onto an aluminum plate with a thermistor temperature data logger (available under the trade name "HOBO MX2303" from Onset Computer Partnership, Bern, Massachusetts) embedded in its surface using an optically clear adhesive obtained as 3M OCA 8171, and bonded with an aluminum backing strip (available under the trade name "3M ALUMINUM FOILTAPE 425" from 3M Corporation, St. Paul, Minnesota) to create the radiant cooling plate RCP2. A one-inch thick layer of polystyrene foam insulation was placed beneath the aluminum control radiant cooling plate RCP2 to thermally insulate it from the ground. Another HOBO MX2303 thermistor temperature data logger was used to measure the ambient air temperature near RCP2. Ambient air temperature and RCP2 temperature were continuously measured for 100 hours, with the thermocouple data logger recording the temperature every minute. The ambient air temperature and RCP2 temperature recorded per minute are the average of 100 hours or 6000 data points. The average ambient air temperature was measured to be 21.5°C. For a sub-environmental cooling difference of -3.1℃, the average RCP2 temperature was measured to be 18.4℃.

[0297] Example 3

[0298] A red-reflective and near-IR-reflective (650nm-1350nm) film (trade name "3M COOL MIRROR 330," also from 3M Inc., St. Paul, Minnesota) was laminated onto a 188-micron-thick microporous PET film (trade name "LUMIRROR XJSA2," from Toray Plastics (USA), North Kingston, Rhode Island) using an optically transparent adhesive (trade name "3M OCA 8171," from 3M Inc., St. Paul, Minnesota). For example... Figure 18 As shown, prior to lamination, the 3M logo was drawn on the LUMIRROR XJSA2 microporous PET film using a black permanent marker (the 3M logo, obtained from Newell Brands, Oak Brook, IL, under the trade name "SHARPIE").

[0299] A red reflective microporous composite film was then laminated onto an aluminum plate with a thermistor temperature data logger (trade name "HOBO MX2303" from Onset Computer Partnership, Bern, Massachusetts) embedded in its surface using an optically clear adhesive obtained as 3M OCA 8171, and bonded with an aluminum backing strip (trade name "3M ALUMINUM FOILTAPE 425" from 3M Corporation, St. Paul, Minnesota) to create the radiant cooling plate RCP3. A one-inch thick layer of polystyrene foam insulation was placed beneath the aluminum control radiant cooling plate RCP3 to thermally insulate it from the ground. Another HOBO MX2303 thermistor temperature data logger was used to measure the ambient air temperature near RCP3. Ambient air temperature and RCP3 temperature were continuously measured for 100 hours, with the thermocouple data logger recording the temperature every minute. The ambient air temperature and RCP3 temperature recorded per minute are the average of 100 hours or 6000 data points. The average ambient air temperature was measured to be 21.5°C. For a sub-environmental cooling difference of -2.7℃, the average RCP3 temperature was measured to be 18.8℃.

[0300] Simulation Examples 4 to 6

[0301] The 4x4 matrix method using the Berreman algorithm is used to model the spectra of constructive and destructive interferences generated by the interfaces of layers of materials with different refractive indices. The Berreman 4x4 matrix method is described in the *Journal of the Optical Society of America* (Vol. 62, No. 4, April 1972) and the *Journal of Applied Physics* (Vol. 85, No. 6, March 1999), the contents of which are incorporated herein by reference. The input parameters for this optical model are the refractive index of the single layer, the layer thickness, the number of layers, and the reflection bandwidth including the left and right band edges. The Berreman method is used to calculate the percentage of light reflected and transmitted at each layer interface, and outputs the reflection and transmission spectra. The Berreman method is used to calculate... Figures 20 to 22 The percentage reflectance spectrum of the multilayer optical film (MOF) shown.

[0302] To predict the reflective color of composite MOF plus microporous PET films, a method such as... Figure 19 The model of the recovery cavity is shown. When a light beam is incident on the composite film, it can be directly reflected or transmitted through the MOF, undergo multiple reflections in the cavity between the MOF and the micropore PET, and is eventually reflected or absorbed by the composite film.

[0303] Because reflections from micropore PET are highly diffuse, the light intensity within the cavity can be assumed to be isotropic, i.e., direction-independent. This allows the use of the hemispherical average transmittance and reflectance of the MOF when estimating the total reflectance of the composite film. Specifically, by tracing the light undergoing multiple reflections and transmissions, we can... Figure 19 The formula for each reflection term shown is written as follows:

[0304]

[0305] Where T 前 R 前 It is the specular transmittance and reflectance of the MOF (average value of p and s polarization) (as a function of wavelength and angle); It is the diffuse reflectance of microporous PET (assumed to be a constant of 0.95 in this model); Let be the hemispherical average transmittance and reflectance of the MOF (as a function of wavelength). Using Equation 1, we can sum all the reflection terms to obtain total internal reflection. To account for the relative contributions of specular and diffuse sources, a weighting factor w is introduced, such that w = 1 represents a purely specular source, and w = 0 represents a purely diffuse source. The total reflectance of the composite film can then be expressed as...

[0306]

[0307] Equation 2, combined with a 4×4 spectral model, is used to predict the color of reflection from the composite film. To match typical light source conditions, in... Figures 20 to 22 In this study, 10% specular and 90% diffuse light sources were used to generate the predicted colors.

[0308] Simulation Example 4: Light Red MOF + Microporous PET

[0309] The microporous diffuse reflective white PET film, purchased from Toray Industries under the trade name "LUMIRROR XJSA2" and used in Examples 1 to 3 above, was simulated as a diffuse reflector in the solar spectrum with a diffuse reflectance of 95%. A simulated MOF of 275 alternating layers of PET and coPMMA in a quarter-wavelength stack was simulated as being laminated to the microporous PET film with an optically transparent pressure-sensitive adhesive. The MOF had left and right band edges at 400 nm and 600 nm, respectively. Under diffuse light, the simulated color range of the composite film in reflection was from light red (on-axis) to gold (off-axis). The simulated solar reflectance was 92.68%. Since the materials and construction were similar to the previous examples, the emissivity (approximately 0.92) in the infrared wavelength range of 4 μm to 20 μm was assumed to remain constant.

[0310] Figure 20 Plots of simulated reflectance spectra of the MOF-only model are provided at incident angles of 0°, 30°, and 60°.

[0311] Table 1. Reflectance La*b* values ​​of composite MOF + microporous PET film from incident angles of 0° to 70° .

[0312]

[0313]

[0314] Simulation Example 5: Green MOF + Microporous PET

[0315] A microporous diffuse reflective white PET film, purchased from Toray Industries under the trade name "LUMIRROR XJSA2" and used in Examples 1 to 3 above, was simulated as a diffuse reflector in the solar spectrum with a diffuse reflectance of 95%. A simulated MOF of 550 (275×2) alternating layers of PET and coPMMA in a quarter-wavelength stack was simulated as being laminated to the microporous PET film with an optically transparent pressure-sensitive adhesive. The MOF had two groups, each with 275 layers. The first group had left band edges / right band edges at 550 nm and 750 nm, respectively. The second group had left band edges / right band edges at 400 nm and 500 nm, respectively. Leakage between the two groups in the 500 nm to 550 nm range produced a saturated green color. Under diffuse light, the simulated color range of the composite film in reflection was from green (on-axis) to violet (off-axis). The simulated solar reflectance was 91.87%. Since the materials and construction are similar to those of the previous embodiments, the emissivity (approximately 0.92) of infrared wavelengths from 4 micrometers to 20 micrometers is assumed to remain unchanged.

[0316] Figure 21 Plots of simulated reflectance spectra of the MOF-only model are provided at incident angles of 0°, 30°, and 60°.

[0317] Table 2. Reflectance La*b* values ​​of composite MOF + microporous PET film from incident angles of 0° to 70°. .

[0318]

[0319]

[0320] Simulation Example 6: Dark Blue MOF + Microporous PET

[0321] A microporous diffuse reflective white PET film, purchased from Toray Industries under the trade name "LUMIRROR XJSA2" and used in Examples 1 to 3 above, was simulated as a diffuse reflector in the solar spectrum with a diffuse reflectance of 95%. A simulated MOF of 550 (275×2) alternating layers of PET and coPMMA in a quarter-wavelength stack was simulated as being laminated to the microporous PET film with an optically transparent pressure-sensitive adhesive. The MOF had two groups, each with 275 layers. The first group had left band edges / right band edges at 500 nm and 750 nm, respectively. The second group had left band edges / right band edges at 400 nm and 450 nm, respectively. Leakage between the two groups in the 450 nm to 500 nm range produced a deep blue color. The simulated color range of the composite film reflected under a diffuse light source was from deep blue (on-axis) to deep red (off-axis). The simulated solar reflectance was 91.98%. Since the materials and construction are similar to those of the previous embodiments, the emissivity (approximately 0.92) of infrared wavelengths from 4 micrometers to 20 micrometers is assumed to remain unchanged.

[0322] Figure 22 Plots of simulated reflectance spectra of the MOF-only model are provided at incident angles of 0°, 30°, and 60°.

[0323] Table 3. Reflectance La*b* values ​​of composite MOF + microporous PET film from incident angles of 0° to 70°. .

[0324] θ L a* b* 0 43.31 15.94 -41.92 5 43.24 16.89 -42.68 10 43.01 19.79 -44.91 15 42.63 24.27 -48.12 20 42.10 29.92 -51.76 25 41.45 35.32 -54.52 30 40.74 38.55 -54.77 35 40.10 37.78 -51.07 40 39.62 32.67 -42.97 45 39.43 24.76 -30.87 50 39.72 18.39 -16.71 55 40.72 18.86 -4.80 60 42.46 24.78 3.62

[0325] Foreseeable modifications and alterations to the invention will be apparent to those skilled in the art without departing from its scope and spirit. The invention should not be limited to the embodiments shown in this application for illustrative purposes.

Claims

1. A radiation-cooled article, the radiation-cooled article comprising: a) A white diffuse reflective microporous layer, wherein the white diffuse reflective microporous layer has a solar-weighted reflectivity of 0.8 or greater for vertically incident electromagnetic radiation with wavelengths in the range of 350 nm to 2500 nm; and b) A non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse reflection microporous layer, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm.

2. The radiation-cooled article according to claim 1, wherein the white diffuse-reflective microporous layer has a solar-weighted reflectivity of 0.85 or greater for vertically incident electromagnetic radiation with wavelengths in the range of 350 nm to 2500 nm.

3. The radiation-cooled article according to claim 2, wherein the white diffuse-reflective microporous layer has a solar-weighted reflectivity of 0.9 or greater for vertically incident electromagnetic radiation with wavelengths in the range of 350 nm to 2500 nm.

4. The radiation-cooled article according to claim 3, wherein the white diffuse-reflective microporous layer has a solar-weighted reflectivity of 0.95 or greater for vertically incident electromagnetic radiation with wavelengths in the range of 350 nm to 2500 nm.

5. The radiation-cooled product according to claim 1, wherein the white diffuse-reflective microporous layer comprises a microporous membrane.

6. The radiation-cooled article according to claim 1, wherein the white diffuse-reflective microporous layer comprises white inorganic particles, aromatic polyester particles, or both.

7. The radiation-cooled article according to claim 1, wherein the non-white colored reflective film comprises a multilayer optical film, the multilayer optical film comprising alternating layers of polyethylene terephthalate (PET) and methyl methacrylate copolymer (coPMMA) or alternating layers of PET and fluoropolymers.

8. The radiation-cooled article according to claim 1, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 380 nm to 450 nm, 400 nm to 500 nm, 450 nm to 500 nm, 500 nm to 600 nm, or 600 nm to 700 nm.

9. The radiation-cooled article according to claim 1, wherein the non-white colored reflector further reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 700 nm to 2000 nm.

10. The radiation-cooled article according to claim 1, further comprising one or more markings present on the main surface of at least one of the white diffuse microporous layer or the non-white colored reflective film.

11. The radiation-cooled article of claim 10, wherein the one or more markings comprise at least one infrared-reflective pigment.

12. The radiation-cooled article of claim 1, further comprising a hard coating or film layer disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer, wherein the hard coating or film layer is an outer layer.

13. The radiation cooling article of claim 1, further comprising a protective layer containing a fluoropolymer, the protective layer being disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer, wherein the protective layer is an outer layer, and wherein the protective layer optionally includes a surface structure.

14. The radiation-cooled article of claim 1, further comprising an antifouling layer disposed adjacent to the main surface of the non-white colored reflective film and opposite to the white diffuse microporous layer, wherein the antifouling layer is an outer layer, wherein the antifouling layer includes an outwardly facing antifouling surface extending along an axis, a plane containing the axis defining a cross-section of the antifouling layer and intersecting the surface to define lines describing the surface in two dimensions, the antifouling layer comprising: a) A series of microstructures at least partially defined by the line, the line defining a series of alternating micropeaks and microspaces along the axis, wherein 1) the boundary between each adjacent micropeak and microspace includes at least one of a bend or inflection point of the line; or 2) each microspace includes a maximum absolute slope defining an angle of up to 30 degrees from the axis, wherein each micropeak includes a first microsegment defining a first average slope and a second microsegment defining a second average slope, and wherein the angle formed between the first average slope and the second average slope is up to 120 degrees; and b) A plurality of nanostructures at least partially defined by the line, the line defining at least a series of nanopeaks disposed along the axis in at least the microspace. Each nanopeak has a height, and the height of each corresponding micropeak is at least 10 times the height of the nanopeak.

15. The radiation-cooled article of claim 12, wherein the hard coating or film layer comprises ceramic or glass beads, ceramic or glass bubbles, or a combination thereof.

16. The radiation cooling article of claim 13, wherein the protective layer comprises ceramic or glass beads, ceramic or glass bulbs, or combinations thereof.

17. The radiation cooling article of claim 14, wherein the antifouling layer comprises ceramic or glass beads, ceramic or glass bulbs, or combinations thereof.

18. The radiation cooling product according to claim 1, further comprising an infrared reflective layer disposed between the white diffuse reflection microporous layer and the non-white colored reflective film, or adjacent to the non-white colored reflective film and opposite to the white diffuse reflection microporous layer, wherein the infrared reflective layer has an average reflectivity of at least 50% in the wavelength range of 700 nm to 2000 nm.

19. The radiation-cooled article of claim 1, further comprising an ultraviolet-reflective multilayer optical film disposed adjacent to the non-white colored reflective mirror film and opposite to the white diffuse microporous layer, wherein the ultraviolet-reflective multilayer optical film has a reflectivity of at least 50% for most ultraviolet radiation in the range of at least 340 nm but less than 400 nm.

20. The radiation cooling article according to claim 1, further comprising a transparent adhesive bonding layer disposed between the white diffuse reflection microporous layer and the non-white colored reflective film.

21. The radiation cooling article according to claim 1, further comprising a degassing adhesive, the degassing adhesive being disposed adjacent to the white diffuse microporous layer and opposite to the non-white colored reflective film.

22. The radiation-cooled article according to claim 1, wherein the radiation-cooled article has an average electromagnetic radiation absorbance of at least 0.80 in the wavelength range of 8 micrometers to 13 micrometers.

23. The radiation-cooled article according to claim 1, wherein the radiation-cooled article exhibits passive radiation cooling to below ambient temperature under direct sunlight.

24. A composite cooling system comprising a radiant cooling article attached to a vehicle or trailer according to any one of claims 1 to 23.

25. A multi-surface passive cooling article, the multi-surface passive cooling article comprising: A plurality of first elements defining the outer surface of a first element, the plurality of first elements being defined with a first absorbance greater than or equal to 0.6 in the atmospheric window wavelength range of 8 micrometers to 13 micrometers, and a first average reflectance greater than or equal to 80% in the solar wavelength range of 0.4 micrometers to 2.5 micrometers; At least one of the first elements comprises a radiation cooling layer, the radiation cooling layer comprising: a) a white diffuse reflective microporous layer having a solar-weighted reflectivity of 0.8 or greater for vertically incident electromagnetic radiation with a majority wavelength in the range of 350 nm to 2500 nm; and b) a non-white colored reflective film having a plurality of first optical layers and a plurality of second optical layers, the non-white colored reflective film being disposed adjacent to the main surface of the white diffuse reflective microporous layer, wherein the non-white colored reflective film reflects a wavelength bandwidth of at least 30 nm in the wavelength range of 350 nm to 700 nm; and A plurality of second elements defining the outer surface of a second element, the plurality of second elements defining a second absorbance of less than or equal to 0.5 in the atmospheric window wavelength range and a second average reflectance of greater than or equal to 60% in the solar wavelength range; The plurality of first elements and the plurality of second elements are dispersed to form a main structure, the main structure having a first main surface including the outer surfaces of the first elements and the outer surfaces of the second elements, and a second main surface opposite to the first main surface; The main structure has a first end region and a second end region, wherein the outer surface of the first element faces a first direction toward the first end region, and the outer surface of the second element faces a second direction toward the second end region.

26. The multi-surface passive cooling article of claim 25, wherein the white diffuse microporous layer has a solar-weighted reflectivity of 0.85 or greater for vertically incident electromagnetic radiation in the range of 350 nm to 2500 nm.

27. The multi-surface passive cooling article of claim 26, wherein the white diffuse microporous layer has a solar-weighted reflectivity of 0.9 or greater for vertically incident electromagnetic radiation in the range of 350 nm to 2500 nm.

28. The multi-surface passive cooling article of claim 27, wherein the white diffuse microporous layer has a solar-weighted reflectivity of 0.95 or greater for vertically incident electromagnetic radiation in the range of 350 nm to 2500 nm.

Images