阅读说明：本技术 抗反射表面结构 (Anti-reflection surface structure ) 是由 蒂莫西·J·赫布林克 托德·G·佩特 莫塞斯·M·大卫 詹姆斯·P·布尔克 维维安·W·琼斯 于 2018-12-21 设计创作，主要内容包括：本发明提供了抗反射制品,该抗反射制品包括限定抗反射表面的层。抗反射表面包括沿轴线延伸的一系列交替的微峰和微空间。该表面还包括沿轴线延伸的一系列纳米峰。纳米峰至少设置在微空间和任选的微峰上。制品可设置在光伏组件或天窗上以减少反射并且抵抗灰尘和污垢的收集。(The present invention provides an antireflective article that includes a layer defining an antireflective surface. The anti-reflective surface includes a series of alternating micro-peaks and micro-spaces extending along an axis. The surface also includes a series of nanopeaks extending along the axis. The nanopeaks are disposed at least on the microspaces and optional micropeaks. The article may be disposed on a photovoltaic module or a skylight to reduce reflection and resist the collection of dust and dirt.)

1. An article comprising a layer defining an antireflective 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 delineating the surface in two dimensions, the layer comprising:

a series of microstructures at least partially defined by the line, the line defining a series of alternating micro-peaks and micro-spaces along the axis, wherein each micro-space comprises a maximum absolute slope defining an angle of at most 30 degrees from the axis, wherein each micro-peak comprises a first micro-segment defining a first average slope and a second micro-segment defining a second average slope, and wherein an angle formed between the first average slope and the second average slope is at most 120 degrees; and

a plurality of nanostructures at least partially defined by the lines, the lines defining at least a series of nanopeaks disposed on at least the microspaces along the axis,

wherein each nanopeak has a height, and the height of each corresponding microfeak is at least 10 times the height of the nanopeak.

2. An article comprising a layer defining an antireflective 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 delineating the surface in two dimensions, the layer comprising:

a series of microstructures at least partially defined by the line, the line defining a series of alternating micro-peaks and micro-spaces along the axis, wherein a boundary between each adjacent micro-peak and micro-space comprises at least one of a bend or an inflection point of the line; and

a plurality of nanostructures at least partially defined by the lines, the lines defining at least a series of nanopeaks disposed on at least the microspaces along the axis,

wherein each nanopeak has a height, and the height of each corresponding microfeak is at least 10 times the height of the nanopeak.

3. The article of claim 1, wherein a first average slope of the micro-peaks is positive and a second average slope of the micro-peaks is negative.

4. The article of claim 1 or3, wherein an absolute value of a first average slope of the microfeaks is equal to an absolute value of a second average slope of the microfeaks.

5. The article of any preceding claim, wherein the width of each micro-space is at least one of: at least 10% or at least 10 microns of the corresponding micro-peak distance.

6. The article of any preceding claim, wherein the micro-peak distance between micro-peaks is in the range of 1 micron to 1000 microns.

7. The article of any preceding claim, wherein the height of the micro-peaks is at least 10 microns.

8. The article of any preceding claim, wherein each nanopeak comprises a first nanopartide defining a first average slope and a second nanopartide defining a second average slope, wherein an angle formed between the first average slope of the nanopeak and the second average slope of the nanopeak is at most 120 degrees.

9. The article of claim 8, wherein an absolute value of a first average slope of the nanopeak is different from an absolute value of a second average slope of the nanopeak.

10. The article of any preceding claim, wherein the plurality of nanostructures is further disposed on the micro-peak.

11. The article of any preceding claim, wherein each nanopeak defines a nanopeak distance and the corresponding microfeak defines a microfeak distance that is at least 10 times the nanopeak distance.

12. The article of any preceding claim, wherein the maximum nanopeak distance between nanopeaks is in the range of 1 nanometer to 1 micrometer.

13. The article of any preceding claim, wherein the layer defining the antireflective surface comprises at least one of a fluoropolymer, a polyolefin polymer, or a uv-stable material.

14. The article of any preceding claim, wherein the nanopeak comprises at least one masking element.

15. The article of claim 14, wherein the masking element has a diameter of at most 1 micron.

16. The article of any preceding claim, wherein the micro-peaks are non-uniform in at least one of height or shape.

17. The article of any preceding claim, further comprising a uv-stable adhesive coupled to a side of the layer opposite the antireflective surface, wherein the adhesive is at least one of a self-wetting to glass or a gassing adhesive.

18. A method of forming an article comprising a layer defining an antireflective surface, the method comprising:

forming a series of microstructures on a surface of the layer, the series of microstructures comprising a series of alternating micro-peaks and micro-spaces along an axis;

disposing a series of nanoscale masking elements along the axis over at least the microspaces, wherein the masking elements define a maximum diameter and the height of corresponding microspeaks is at least 10 times the maximum diameter of the masking elements; and

exposing the surface of the layer to reactive ion etching to form a plurality of nanostructures on the surface of the layer, the nanostructures comprising a series of nanopeaks along the axis, each nanopeak comprising the masking element and a pillar between the masking element and the layer.

19. A method of forming an article comprising a layer defining an antireflective surface, the method comprising:

extruding a hot melt material comprising a uv stabilizing material;

shaping an extruded material with a microreplication tool comprising a mirror image of a series of microstructures to form the series of microstructures on the surface of the layer, the series of microstructures comprising a series of alternating microfeaks and microspaces along an axis; and

forming a plurality of nanostructures on at least the surface of the layer over the micro-spaces, the plurality of nanopeaks comprising at least a series of nanopeaks along the axis.

20. The method of claim 19, wherein the plurality of nanopeaks comprises at least one series of nanopeaks along the axis.

Background

Antireflective surfaces are used in solar applications. For example, reflection from the front surface of the photovoltaic modules may reduce their power output by more than 3%. A great deal of effort has been made to solve this problem in the industry. In one example, the sintered nanosilica solution coating has provided a 1% to 2% reduction in surface reflection, resulting in a 1% to 2% increase in photovoltaic power output. In another example, the microstructured prisms applied to the front surface of the photovoltaic cell have provided an increase in power output of the photovoltaic module of even greater than 3%, but when subjected to environmental conditions such as dust and dirt, the photovoltaic power output decreases. It is desirable to have additional options or alternatives when designing anti-reflective surfaces that are exposed to environmental contaminants such as dust and dirt.

Disclosure of Invention

The present disclosure relates to antireflective surfaces. In particular, the present disclosure relates to antireflective surface structures comprising microstructures and nanostructures. The microstructures can be arranged as at least a series of alternating micro-peaks and micro-spaces. The nanostructures can be arranged as at least a series of nanopeaks disposed on a microspace and optionally a microspeak.

Various aspects of the present disclosure relate to articles having a layer defining an antireflective surface extending along an axis. A plane containing the axis defines a cross-section of the layer and intersects the surface to define a line delineating the cross-sectional profile of the surface. The layer includes a series of microstructures at least partially defined by lines. The line defines a series of alternating micro-peaks and micro-spaces along the axis. Each micro-space includes a maximum absolute slope defining an angle of at most 30 degrees from the axis. Each of the microflakes includes a first microfracture defining a first average slope and a second microfracture defining a second average slope. An angle formed between the first average slope and the second average slope is at most 120 degrees. The layer also includes a plurality of nanostructures at least partially defined by the lines. The line defines at least one series of nanopeaks disposed along an axis on at least a microspace. Each nanopeak has a height, and the height of each corresponding microfeak is at least 10 times the height of the nanopeak.

Various aspects of the present disclosure relate to articles having a layer defining an antireflective surface extending along an axis. A plane containing the axis defines a cross-section of the layer and intersects the surface to define a line delineating the cross-sectional profile of the surface. The layer includes a series of microstructures at least partially defined by lines. The line defines a series of alternating micro-peaks and micro-spaces along the axis. The boundary between each adjacent microfeak and the microspace includes at least one of a bend or an inflection point of the line. The layer also includes a plurality of nanostructures at least partially defined by the lines. The line defines at least one series of nanopeaks disposed along an axis on at least a microspace. Each nanopeak has a height, and the height of each corresponding microfeak is at least 10 times the height of the nanopeak.

Various aspects of the present disclosure relate to methods of forming articles including a layer defining an antireflective surface. The method includes forming a series of microstructures on a surface of a layer. The series of microstructures includes a series of alternating micro-peaks and micro-spaces along an axis. The method also includes disposing a series of nanoscale masking elements along the axis over at least the micro-space. The masking elements define a maximum diameter, and the height of the corresponding micro-peaks is at least 10 times the maximum diameter of the masking elements. The method also includes exposing the surface of the layer to reactive ion etching to form a plurality of nanostructures on the surface of the layer, the nanostructures including a series of nanopeaks along an axis. Each nanopeak includes a masking element and a pillar between the masking element and the layer.

Various aspects of the present disclosure relate to methods of forming articles including a layer defining an antireflective surface. The method includes extruding a hot melt material including a uv stabilizing material. The method also includes shaping the extruded material with a microreplication tool that includes a mirror image of the series of microstructures to form a series of microstructures on a surface of the layer. The series of microstructures includes a series of alternating micro-peaks and micro-spaces along an axis. The method also includes forming a plurality of nanostructures on a surface of the layer at least over the micro-spaces. The plurality of nanopeaks includes at least one series of nanopeaks along an axis.

The present disclosure may be more completely understood in consideration of the following drawings and accompanying detailed description of various aspects of the disclosure.

Unless defined otherwise, all scientific and technical terms used herein have the same meaning as commonly understood in the art. The definitions provided herein will facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure.

As used herein, the term "light" refers to energy in the electromagnetic spectrum that can be characterized by wavelength. Non-limiting examples of "light" include solar energy, Infrared (IR) light, visible light, or Ultraviolet (UV) light. The solar energy may include at least one of IR light, visible light, or UV light.

As used herein, the term "percent (%) average transmission" refers to the results of the light measurement technique described in the examples. The increase in transmittance can also be measured indirectly by the increase in photovoltaic module power output when the film to be measured is laminated to the surface of the photovoltaic module.

As used herein, the term "average percent (%) reflection" refers to a value calculated from the average percent (%) transmission. In particular, the% reflection (% R) may be calculated based on the% transmission (% T) at each sampling frequency. The calculated% R may be averaged to determine the average% R of the light.

As used herein, "transparent" refers to a polymeric film having an average transmission of light of greater than 1%.

As used herein, the term "antireflective" refers to a low average% reflection or a high average% transmission of a transparent polymer film.

As used herein, the term or prefix "micro" refers to at least one dimension defining a structure or shape in the range of 1 micron to 1 millimeter. For example, the microstructures can have a height or width in the range of 1 micron to 1 millimeter.

As used herein, the term or prefix "nano" refers to at least one dimension that defines a structure or shape that is less than 1 micron. For example, the nanostructures may have at least one of a height or a width of less than 1 micron.

As used herein, the term "ultraviolet light stabilizing material" refers to a material that is resistant to Ultraviolet (UV) light degradation, as measured by a color change with a colorimeter (e.g., a colorimeter available under the trade designation "HUNTER LAB" from HUNTER Associates Laboratory, inc., Reston, VA), or by a loss of light transmittance with a spectrophotometer (e.g., a spectrophotometer available under the trade designation "PERKINELMER LAMBDA 1050" from perkin elmer, Hopkinton, MA) of Hopkinton, massachusetts). Non-limiting examples of intrinsically UV stable polymers include fluoropolymers and silicone polymers. Other polymers such as acrylates, polyethylenes, polyolefins, cyclic olefin copolymers and polyurethanes can be UV stabilized by the addition of ultraviolet absorbers (UVAs) and Hindered Amine Light Stabilizers (HALS).

As used herein, the term "fluoropolymer" refers to at least one polymer that includes fluorine. Non-limiting examples of fluoropolymers include polyvinylidene fluoride (PVDF), copolymers of polyvinylidene fluoride and hexafluoropropylene (copdf), copolymers of hexafluoropropylene, tetrafluoroethylene, and ethylene (HTE), copolymers of Ethylene and Tetrafluoroethylene (ETFE), copolymers of fluorinated ethylene and fluorinated propylene (FEP), copolymers of Ethylene and Chlorotrifluoroethylene (ECTFE), and copolymers of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride (THV). The fluoropolymer may be used in combination with at least one other fluoropolymer.

As used herein, the term "polyolefin polymer" refers to at least one polymer comprising a polyolefin. Non-limiting examples of polyolefins include Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE), Cyclic Olefin Polymer (COP), Cyclic Olefin Copolymer (COC), polymethylpentene (PMP), and High Density Polyethylene (HDPE).

As used herein, the term "self-wetting" refers to the ability of a liquid to form an interface with a solid surface. To determine the degree of wetting, the contact angle (q) formed between the liquid and the solid surface is measured. The smaller the contact angle and the smaller the surface tension, the greater the wettability may be. Effective wetting may require that the surface tension of the adhesive be less than or equal to the surface tension of the substrate. Preferably, the self-wetting adhesive does not trap air bubbles between the adhesive and the substrate to which it is adhered.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. Herein, the term "at most" or "not more than" a number (e.g., up to 50) includes the number (e.g., 50), and the term "at least" a number (e.g., not less than 5) includes the number (e.g., 5).

The term "coupled" means that the elements are attached to each other either directly (directly in contact with each other) or indirectly (having at least one element between and attaching two elements).

Orientation-related terms, such as "top," "bottom," "side," and "end," are used to describe relative positions of components and are not intended to limit the orientation of the contemplated embodiments. Unless the content clearly indicates otherwise, for example, embodiments described as having "top" and "bottom" also encompass embodiments in which rotation is in various directions.

Reference to "one embodiment," "an embodiment," "certain embodiments," or "some embodiments," etc., means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases in various places throughout this disclosure are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in some embodiments.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

As used herein, "having," including, "" comprising, "and the like are used in their open sense and generally refer to" including, but not limited to. It is understood that "consisting essentially of …" and "consisting of …" are included in the "comprise".

The term "and/or" means one or all of the listed elements or a combination of at least two of the listed elements.

Drawings

FIG. 1 is a perspective view of an environment for use with an antireflective surface structure including a building and a photovoltaic module or skylight.

Fig. 2A, 2B, and 2C are views of an antireflective surface structure having a microstructure. Fig. 2A shows a perspective view of a cross section with respect to the xyz axis. Fig. 2C shows a cross-section of fig. 2A in the xz-plane. Fig. 2B shows another cross section in the yz plane.

Fig. 3 is a cross-sectional view in the xz plane of various nanostructures of the antireflective surface structures of fig. 2A-2C.

Fig. 4 is a cross-sectional view of various nanostructures including masking elements in the xz plane as an alternative to the nanostructures of fig. 3 that may be used with the antireflective surface structures of fig. 2A-2C.

Fig. 5A and 5B show representations of lines representing cross-sectional profiles of different forms of microstructures for an antireflective surface structure in the xz-plane.

Fig. 6 is a graph showing the relative power increase of photovoltaic modules based on different forms of antireflective surface structures tested.

FIG. 7 is a table showing data used to generate the chart of FIG. 6.

Fig. 8 is a cross-sectional view of one embodiment of an antireflective surface structure of a microstructure having no Skipped Toothed Rib (STR) patterns in the xz plane.

Fig. 9 is a cross-sectional view of another embodiment of an antireflective surface structure with microstructures and nanostructures in the xz plane without STR patterns.

FIG. 10 is a perspective view of a portion of a first antireflective surface structure with a discontinuous microstructure.

Fig. 11 is a perspective view of a portion of a second anti-reflective surface structure having a discontinuous microstructure.

Fig. 12 and 13 are perspective views of different portions of a third antireflective surface structure with a discontinuous microstructure.

Fig. 14 is a table showing the percent transmission of various films.

FIG. 15 is a cross-sectional view of another embodiment of an antireflective surface structure with skip tooth microstructures and nanostructures on a multilayer film substrate.

Detailed Description

In general, the present disclosure can provide a durable anti-reflective surface that can withstand outdoor elements, such as Ultraviolet (UV) exposure, humidity, rain, dust, and dirt. Although reference is made to solar applications, such as Photovoltaic (PV) modules, the antireflective surfaces described herein can be used with any application that can benefit from a durable antireflective surface that resists fouling. Various other applications will become apparent to those skilled in the art having the benefit of this disclosure.

More specifically, the present disclosure can provide an antireflective surface that includes microstructures and nanostructures. The microstructures may be arranged as a series of alternating micro-peaks and micro-spaces. The micro-peaks may provide anti-reflective properties based at least on the average slope of their side segments. The size and shape of the microspaces between the micropeaks can reduce the adhesion of soil particles to the micropeaks. The nanostructures may be arranged as at least one series of nanopeaks disposed on at least a microspace. The nanostructure can improve the anti-reflective properties of the micro-space, which has a lower maximum slope compared to the micro-peak. The micro-peaks may be more robust to environmental effects than the nano-peaks. Since the microspeaks are separated only by the microspaces, and the microspaces are significantly higher than the nanopeaks, the microspeaks can be used to protect the nanopeaks on the surface of the microspaces from abrasion. Optionally, the nano-peaks may be disposed on the micro-peaks to further improve the anti-reflective properties.

In some applications, the antireflective surface may be part of a layer disposed on the PV assembly. Advantageously, the antireflective surfaces of the present disclosure can provide a desired reduction in surface reflection over a wide range of incident light angles to improve long-term PV power output. These surfaces can also reduce the collection of dirt on the photovoltaic module surface or facilitate easy removal of dirt from the photovoltaic module surface, which can further improve long-term PV power output and can reduce maintenance costs (e.g., cleaning the PV surface) as compared to conventional microstructured prisms. Additionally, these surfaces may be designed to be durable in outdoor environments, which may reduce maintenance costs (e.g., to replace antireflective layers).

The antireflective surface structures described herein may also be beneficial for masking the appearance of the photovoltaic module for aesthetic reasons. Pigments or dyes may be added to the surface structure to further enhance the masking benefit of the antireflective surface structure. Anti-reflection may also be advantageous to reduce unwanted specular reflection or glare, which may be undesirable near airports or roads for practical reasons.

In some architectural applications, the antireflective film may increase sunlight entering a building (such as a transparent deck window, skylight, and greenhouse). In some solar thermal applications where a non-transparent film may be utilized, an antireflective surface may increase the absorption of solar energy, which may be beneficial. In some applications, an anti-reflective surface on a mirror (e.g., a mirror film) can reduce undesirable specular reflection and provide desirable diffuse reflection for aesthetic or practical reasons.

Reference will now be made to the accompanying drawings, which illustrate at least one aspect described in the present disclosure. Like reference numerals are used to refer to like components, steps, etc. It should be understood, however, that the use of reference numerals to refer to elements in each figure is not intended to limit the elements in another figure labeled with the same reference numeral. Additionally, the use of different reference numbers in different figures to refer to elements is not intended to indicate that the different numbered elements may not be the same or similar.

FIG. 1 illustrates an environment 100 for use with an antireflective surface structure 102 that includes a building 104 and a photovoltaic assembly or skylight 106. The anti-reflective surface structure 102 may be disposed on any substrate that may benefit from anti-reflective properties to allow more incident light (especially at various angles) to be transmitted through the surface without being reflected. As shown, the substrate is part of a photovoltaic module or skylight 106. The photovoltaic module is capable of receiving solar energy, converting the solar energy into electricity, and supplying electrical energy. The skylight may transmit sunlight through the interior of the building 104. For illustrative purposes, four antireflective surface structures 102 are shown disposed on four photovoltaic modules or louvers 106. However, any number of antireflective surface structures 102 may be used per substrate.

Photovoltaic modules may benefit from an anti-reflective surface structure 102 because increased electrical energy can be output due to an increase in incident light that may otherwise reflect off the module. Skylights can benefit from the anti-reflective surface structure 102 by being able to increase the amount of daylight transmitted into the building 104.

The photovoltaic assembly 106 may be located in the outdoor environment 100 and subjected to a variety of environmental conditions. In some embodiments, the outdoor environment 100 may expose the anti-reflective surface structure 102 to environmental conditions (e.g., dust, precipitation, or wind). It may be beneficial for the antireflective surface structure 102 to be durable when used under at least these environmental conditions. The anti-reflective surface structure 102 may be oriented to allow environmental contaminants, such as dust, to be easily washed away (e.g., during rain). The anti-reflective structure 102 may comprise a series of ridges and channels 103 extending at least partially in a vertical direction, such that dust and rain water may flow down the channels. When viewed in cross-section, the ridges and channels 103 may resemble alternating peaks and spaces as described in more detail herein.

Fig. 2A, 2B and 2C show cross-sections 200, 201 of an antireflective surface structure, shown as an antireflective layer 208 having an antireflective surface 202 defined by a series of microstructures 218. Cross-sections 200, 201 also show the substrate 206 and the adhesive 204 between the antireflective layer 208 and the substrate. In particular, fig. 2A shows a perspective view of a cross-section 201 with respect to the xyz axis. Fig. 2C shows a cross-section 201 in the xz-plane parallel to the axis 210. Fig. 2B shows a cross-section 200 in the yz plane orthogonal to cross-section 201 and orthogonal to axis 210. Fig. 2A-2C show the antireflective surface 202 as if the layer 208 were on a flat horizontal surface. However, the layer 208 may be flexible and conformable to non-planar substrates.

The antireflective surface 202 may be formed on at least one surface of the layer 208. In some embodiments, microstructures 218 are formed in layer 208. Microstructure 218 and the remainder of layer 208 below the microstructure may be formed of the same material. The layer 208 may be formed of any suitable material capable of defining the microstructures 218, which may at least partially define the antireflective surface 202. The layer 208 may be transparent to light of various frequencies, such as those found in solar energy captured by the photovoltaic assembly 106 (fig. 1). In at least one embodiment, the layer 208 may be non-transparent or even opaque to various frequencies of light. In some embodiments, layer 208 may include a UV stabilizing material. In some embodiments, the layer 208 may comprise a polymeric material, such as a fluoropolymer or a polyolefin polymer.

The layer 208 may be disposed on the substrate 206. The substrate 206 may be part of a larger article, device, or system, such as a photovoltaic module 106 (fig. 1) or a window of a building 104 (fig. 1). In some embodiments, the substrate 206 may include a transparent material (e.g., glass) to allow transmission of various frequencies of light. For example, the photovoltaic assembly 106 can include a substrate 206, which can be made of glass and can cover photovoltaic cells that absorb light for conversion to electricity. In some embodiments, the substrate 206 may be a flexible BARRIER FILM, such as a flexible BARRIER FILM available from 3M Company of st paul, MN under the trade designation "3M ULTRA BARRIER FILM UBF 512". Flexible barrier films are used to protect flexible photovoltaic modules such as Copper Indium Gallium Selenide (CIGS), Copper Zinc Tin Sulfide (CZTS), Organic Photovoltaics (OPVs), transparent OPVs, semi-transparent OPVs and perovskite solar cells.

The adhesive layer 204 may be disposed between the layer 208 and the substrate 206. In some implementations, the adhesive 204 can be in direct contact with at least one of the layer 208 or the substrate 206. The adhesive 204 may be formed of any suitable material capable of adhering to at least one of the layer 208 or the substrate 206. In some embodiments, the adhesive 204 may include a UV stabilizing material. Non-limiting examples of inherently UV stable adhesives are silicone adhesives or other UV stable materials suitable for use in adhesives (e.g., acrylates).

The adhesive 204 may be laid down on the substrate 206 without creating air bubbles therebetween. In some embodiments, adhesive 204 can be any suitable adhesive capable of self-wetting glass, which is commercially available. Alternatively or additionally, the adhesive 204 may be any suitable gassing adhesive, which is commercially available. The outgassing adhesive may have surface structures in the form of channels that allow air to escape from under the adhesive as it is laminated to glass or other substrates (e.g., mirror films).

The anti-reflective surface 202 may extend along an axis 210, e.g., parallel or substantially parallel to the axis. The plane 212 may include the axes 210, e.g., parallel or intersecting, such that the axes 210 are in the plane 212. Both axis 210 and plane 212 may be imaginary configurations as used herein to illustrate various features associated with anti-reflective surface 202. For example, the intersection of plane 212 and anti-reflective surface 202 may define a line 214 describing a cross-sectional profile of the surface as shown in fig. 2C, including micro-peaks 220 and micro-spaces 222 as described in more detail herein. The line 214 may include at least one straight line segment or curved line segment.

The lines 214 may at least partially define a series of microstructures 218. Microstructure 218 may be a three-dimensional (3D) structure disposed on layer 208, and lines 214 may describe only two dimensions (e.g., height and width) of the 3D structure. As can be seen in fig. 2B, microstructures 218 can have a length that extends along surface 202 from one side 230 to another side 232.

The microstructure 218 may include a series of alternating micro-peaks 220 and micro-spaces 222 along or in the direction of the axis 210, which axis 210 may be defined by or included in the line 214. The direction of the axis 210 may coincide with the width dimension. The micro-spaces 222 may each be disposed between a pair of micro-peaks 220. In other words, the plurality of micro-peaks 220 may be separated from each other by at least one micro-space 222. In at least one embodiment, at least one pair of micro-peaks 220 may not include a micro-space 222 therebetween. The pattern of alternating micro-peaks 220 and micro-spaces 222 may be described as "skipped toothed ridges" (STRs). Each of the micro-peaks 220 and micro-spaces 222 may include at least one straight line segment or curved line segment.

The slope of line 214 (e.g., rising with extension) may be defined as the x-coordinate (extension) with respect to the direction of axis 210 and as the y-axis (rising) with respect to plane 212.

The maximum absolute slope may be defined for at least a portion of the line 214. As used herein, the term "maximum absolute slope" refers to the maximum value selected from the absolute values of the slopes throughout a particular portion of line 214. For example, the maximum absolute slope of one of the micro-spaces 222 may refer to the maximum selected from calculating the absolute value of the slope at each point along the line 214 defining the micro-space.

The line defining the maximum absolute slope of each micro-space 222 may be used to define an angle relative to axis 210. In some embodiments, the angle corresponding to the maximum absolute slope may be at most 30 degrees (in some embodiments, at most 25 degrees, 20 degrees, 15 degrees, 10 degrees, 5 degrees, or even at most 1 degree). In some embodiments, the maximum absolute slope of at least some (in some embodiments, all) of the micro-peaks 220 may be greater than the maximum absolute slope of at least some (in some embodiments, all) of the micro-spaces 222.

In some embodiments, the line 214 may include a boundary 216 between each adjacent microfeak 220 and the microspace 222. The boundary 216 may include at least one of a straight line segment or a curved line segment. The boundary 216 may be a point along the line 214. In some embodiments, the boundary 216 may include a bend. The bend may comprise an intersection of two sections of the wire 214. The curve may include a point at which the line 214 changes direction in position (e.g., a change in slope between two different straight lines). The curve may also include a point at which the line 214 has the sharpest change in direction in position (e.g., a sharper turn than an adjacent curved section). In some implementations, the boundary 216 may include an inflection point. The inflection point may be a point of a line in which the curvature direction changes.

Fig. 3 shows the antireflective surface 202 of layer 208 with nanostructures 330, 332 visible in two magnified stacks. At least one microfront 220 can include at least one first micro-segment 224 or at least one second micro-segment 226. The micro-segments 224, 226 may be disposed on opposite sides of the apex 248 of the micro-peak 220. Apex 248 may be, for example, the highest point or local maximum of line 214. Each micro-segment 224, 226 may include at least one of: a straight line segment or a curved line segment.

The lines 214 defining the first and second micro-segments 224, 226 may have first and second average slopes, respectively. The slope may be defined relative to the baseline 250 as the x-axis (extension), with the orthogonal direction being the z-axis (elevation).

As used herein, the term "average slope" refers to the average slope over a particular portion of the line. In some embodiments, the average slope of the first micro-segment 224 may refer to the slope between the endpoints of the first micro-segment. In some embodiments, the average slope of the first micro-segment 224 may refer to an average calculated from the slopes measured at multiple points along the first micro-segment.

Generally, a first average slope of a micro-peak can be defined as positive and a second average slope of a micro-peak can 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 the 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 embodiments, the absolute value of each average slope of the micro-segments 224, 226 may be greater than the absolute value of the average slope of the micro-space 222.

The angle a of the micro-peak 220 may be defined between a first average slope of the micro-peak and a second average slope of the micro-peak. In other words, a first average slope and a second average slope may be calculated, and then the angle between these calculated lines may be determined. For purposes of illustration, angle a is shown in relation to first micro-segment 224 and second micro-segment 226. However, in some embodiments, when the first and second micro-segments are not straight lines, angle a may not necessarily equal the angle between the two micro-segments 224, 226.

Angle a may be in a range that provides sufficient anti-reflective properties to surface 202. In some embodiments, angle a may 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 (in some embodiments, at least 25 degrees, 40 degrees, 45 degrees, or even at least 50 degrees) at the lower end. In some embodiments, angle a is at most 75 degrees (in some embodiments, at most 60 degrees, or even at most 55 degrees) at the high end.

The micro-peak 220 may be any suitable shape capable of providing the angle A based on the average slope of the micro-segments 224, 226. In some embodiments, the micro-peaks 220 are formed in a generally triangular shape. In some embodiments, the micro-peaks 220 are not triangular in shape. The shape may be symmetric across a z-axis that intersects the vertex 248. In some embodiments, the shape may be asymmetric.

Each micro-space 222 may define a micro-space width 242. The micro-space width 242 may be defined as the distance between corresponding boundaries 216, which may be between adjacent micro-peaks 220.

The minimum value of the micro-space width 242 may be defined in microns. In some embodiments, the micro-space width 242 can be at least 10 microns (in some embodiments, at least 20 microns, 25 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 75 microns, 80 microns, 90 microns, 100 microns, 150 microns, 200 microns, or even at least 250 microns). In some applications, the micro-space width 242 is at least 50 microns (in some embodiments, at least 60 microns) at the lower end. In some applications, the micro-space width 242 is at most 90 microns (in some embodiments, at most 80 microns) at the high end. In some applications, the micro-space width 242 is 70 microns.

As used herein, the term "peak distance" refers to the distance between successive peaks or between the nearest pair of peaks measured at each vertex or highest point of a peak.

The micro-space width 242 may also be defined relative to the micro-peak distance 240. In particular, a minimum value of the micro-space width 242 may be defined relative to a corresponding micro-peak distance 240, which may refer to the distance between the nearest pair of micro-peaks 220 that surround the micro-space 222, measured at each apex 248 of the micro-peaks. In some embodiments, the micro-space width 242 may be at least 10% (in some embodiments, at least 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, or even at least 90%) of the maximum of the micro-peak distance 240. In some embodiments, the minimum value of the micro-space width 242 is at least 30% (in some embodiments, at least 40%) of the maximum value of the micro-peak distance 240 at the lower end. In some embodiments, the minimum value of the micro-space width 242 is at most 60% (in some embodiments, at most 50%) of the maximum value of the micro-peak distance 240 at the high end. In some embodiments, the micro-space width 242 is 45% of the micro-peak distance 240.

The minimum of the micro-peak distance 240 may be defined in microns. In some embodiments, the micro-peak distance 240 can be at least 1 micron (in some embodiments, at least 2 microns, 3 microns, 4 microns, 5 microns, 10 microns, 25 microns, 50 microns, 75 microns, 100 microns, 150 microns, 200 microns, 250 microns, or even at least 500 microns). In some embodiments, the microfeak distance 240 is at least 100 microns.

The maximum value of the micro-peak distance 240 may be defined in microns. The micro-peak distance 240 can be up to 1000 microns (in some embodiments, up to 900 microns, 800 microns, 700 microns, 600 microns, 500 microns, 400 microns, 300 microns, 250 microns, 200 microns, 150 microns, 100 microns, or even up to 50 microns). In some embodiments, the microfeak distance 240 is at most 200 microns at the high end. In some embodiments, the micro-peak distance 240 is at least 100 microns at the lower end. In some embodiments, the microfeak distance 240 is 150 microns.

Each of the micro-peaks 220 may define a micro-peak height 246. The micro-peak height 246 may be defined as the distance between the baseline 350 and the apex 248 of the micro-peak 220. The minimum of the micro-peak heights 246 can be defined in microns. In some embodiments, the micro-peak height 246 can be at least 10 microns (in some embodiments, at least 20 microns, 25 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 150 microns, 200 microns, or even at least 250 microns). In some embodiments, the micro-peak height 246 is at least 60 micrometers (in some embodiments, at least 70 micrometers). In some embodiments, the micro-peak height 246 is 80 microns.

The plurality of nanostructures 330, 332 may be at least partially defined by the line 214. A plurality of nanostructures 330 may be disposed on at least one of the micro-spaces 222. In particular, the lines 314 defining the nanostructures 330 may include at least one series of nanopeaks 320 disposed on at least one of the micro-spaces 222. In some embodiments, at least one series of nano-peaks 320 of the plurality of nanostructures 332 may also be disposed on at least one micro-peak 220.

Due at least to their size difference, the microstructures 218 may be more durable in wear resistance than the nanostructures 330, 332. In some embodiments, the plurality of nanostructures 332 are disposed only on the microvoids 222, or at least not disposed proximate or adjacent to the apex 248 of the microspeak 220.

Each nanopeak 320 may include at least one of a first nanosections 324 and a second nanosections 326. Each nanopeak 320 may include both nanodegions 324, 326. The nano-segments 324, 326 may be disposed on opposite sides of the apex 348 of the nano-peak 320.

The first nano-segment 324 and the second nano-segment 326 may define a first average slope and a second average slope, respectively, that describe the line 314 defining the nano-segment. For the nanostructures 330, 332, the slope of the line 314 may be defined as the x-axis (extension) relative to the baseline 350, with the orthogonal direction being the z-axis (elevation).

In general, a first average slope of a nanopeak can be defined as positive and a 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 a nanopeak may be equal to the absolute value of the second average slope of the nanopeak (e.g., nanostructure 330). In some embodiments, the absolute values may be different (e.g., nanostructures 332).

Angle B of nanopeak 320 may be defined between lines defined by a first average slope of the nanopeak and a second average slope of the nanopeak. Similar to angle a, angle B as shown is for illustrative purposes and may not necessarily equal any directly measured angle between nano-segments 324, 326.

Angle B may be in a range that provides sufficient anti-reflective properties to surface 202. In some embodiments, angle B may 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 at most 85 degrees (in some embodiments, at most 80 degrees, or even at most 75 degrees) at the high end. In some embodiments, angle B is at least 55 degrees (in some embodiments, at least 60 degrees, or even at least 65 degrees) at the lower end. In some embodiments, angle B is 70 degrees.

Angle B may be the same or different for each nanopeak 320. For example, in some embodiments, the angle B of the nanopeak 320 on the microspeak 220 may be different from the angle B of the nanopeak 320 on the microspace 222.

Nanoproke 320 may be any suitable shape capable of providing angle B based on a line defined by the average slope of nanopartilces 324, 326. In some embodiments, the nanopeaks 320 are formed in a generally triangular shape. In at least one embodiment, the nanopeaks 320 are not triangular in shape. The shape may be symmetric across vertex 348. For example, the nanopeaks 320 of the nanostructures 330 disposed on the micro-spaces 222 may be symmetrical. In at least some embodiments, the shape can be asymmetric. For example, the nanopeaks 320 of the nanostructures 332 disposed on the microfeaks 220 may be asymmetric, with one nanosections 324 being longer than the other nanosections 326. In some embodiments, the nanopeaks 320 may be formed without undercutting.

Each nano-peak 320 may define a nano-peak height 346. The nano-peak height 346 may be defined as the distance between the baseline 350 and the apex 348 of the nano-peak 320. The minimum of the nanometer peak height 346 can be defined in nanometers. In some embodiments, the nano-peak height 346 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 nano-peak height 346 is at most 250 nanometers (in some embodiments, at most 200 nanometers), particularly for the nanostructures 330 on the micro-spaces 222. In some embodiments, the nano-peak height 346 is in a range from 100 nanometers to 250 nanometers (in some embodiments, 160 nanometers to 200 nanometers). In some embodiments, the nano-peak height 346 is 180 nanometers.

In some embodiments, the nano-peak height 346 is at most 160 nanometers (in some embodiments, at most 140 nanometers), particularly for the nanostructures 332 on the micro-peaks 220. In some embodiments, the nano-peak height 346 is in a range from 75 nanometers to 160 nanometers (in some embodiments, 100 nanometers to 140 nanometers). In some embodiments, the nano-peak height 346 is 120 nanometers.

As used herein, the term "corresponding micro-peaks" or "corresponding micro-peaks" refers to one or both of the micro-peaks 220 on which the nano-peaks 320 are disposed, or the nearest micro-peaks surrounding the micro-spaces if the nano-peaks are disposed on the corresponding micro-spaces 222. In other words, the micro-peak 220 corresponding to the micro-space 222 refers to a micro-peak in a series of micro-peaks before and after the micro-space.

The nano-peak height 346 may also be defined relative to the micro-peak height 246 of the corresponding micro-peak 220. In some embodiments, the corresponding micro-peak height 246 can be at least 10 times (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) the nano-peak height 346. In some embodiments, the corresponding micro-peak height 246 is at least 300 times (in some embodiments, at least 400 times, 500 times, or even at least 600 times) the nano-peak height 346 at the lower end. In some embodiments, the corresponding micro-peak height 246 is at most 900 times (in some embodiments, at most 800 times or even at most 700 times) the nano-peak height 346 at the high end.

A nanopeak distance 340 may be defined between nanopeaks 320. The maximum value of the nanopeak distance 340 may be defined. In some embodiments, the nanopeak distance 340 may 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 nanopeak distance 340 is at most 400 nanometers (in some embodiments, at most 300 nanometers).

A minimum value of the nano-peak distance 340 may be defined. In some embodiments, the nanopeak distance 340 may 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 340 is at least 150 nanometers (in some embodiments, at least 200 nanometers).

In some embodiments, the nanopeak distance 340 is in a range from 150 nanometers to 400 nanometers (in some embodiments, 200 nanometers to 300 nanometers). In some embodiments, the nanopeak distance 340 is 250 nanometers.

The nano-peak distance 340 may be defined relative to the micro-peak distance 240 between corresponding micro-peaks 220. In some embodiments, the corresponding micro-peak distance 240 is at least 10 times (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) the nano-peak distance 340. In some embodiments, the corresponding micro-peak distance 240 is at least 200 times (in some embodiments, at least 300 times) the nano-peak distance 340 at the lower end. In some embodiments, the corresponding micro-peak distance 240 is at most 500 times (in some embodiments, at most 400 times) the nano-peak distance 340 at the high end.

In some embodiments forming the antireflective surface 202 of layer 208, the method may include extruding a hot melt material with a UV stabilizing material. The extruded material may be formed using a microreplication tool. The microreplication tool may comprise a mirror image of a series of microstructures that can form a series of microstructures on the surface of layer 208. The series of microstructures may include a series of alternating micro-peaks and micro-spaces along an axis. A plurality of nanostructures may be formed on a surface of the layer at least over the micro-spaces. The plurality of nanopeaks can include at least one series of nanopeaks along the axis.

In some embodiments, the plurality of nanostructures may be formed by exposing the surface to reactive ion etching. For example, masking elements may be used to define the nanopeaks.

In some embodiments, the plurality of nanostructures may be formed by shaping the extruded material with a microreplication tool that also has ion etched diamonds. The method can involve providing a diamond tool, wherein at least a portion of the tool comprises a plurality of tips, wherein the tips can have a pitch of less than 1 micron; and cutting the substrate with a diamond tool, wherein the diamond tool may be oriented at a pitch (p)₁) And (4) entering and exiting. The diamond tool may have a maximum cutter width (p)₂) And is and

the nanostructures may be characterized as being embedded within the microstructured surface of layer 208. The shape of the nanostructures may generally be defined by adjacent microstructured materials, except for the portions of the nanostructures exposed to air.

The microstructured surface layer comprising nanostructures may be formed by using a multi-tipped diamond tool. A Diamond Turning Machine (DTM) may be used to create a microreplication tool for creating an antireflective surface structure comprising nanostructures, as described in U.S. patent publication 2013/0236697(Walker et al). Microstructured surfaces that also include nanostructures can be formed by using a multi-tipped diamond tool, which can have a single radius, wherein the plurality of tips have a pitch of less than 1 micron. Such multi-tipped diamond tools may also be referred to as "nanostructured diamond tools". Thus, the microstructured surface (where the microstructures further comprise nanostructures) may be formed simultaneously during diamond tool fabrication of the microstructured tool. Focused ion beam milling processes may be used to form tool tips, as well as to form valleys of diamond tools. For example, focused ion beam milling may be used to ensure that the inner surfaces of the tool tips meet along a common axis to form the bottom of the valley. Focused ion beam milling may be used to form features in the valleys, such as concave or convex arc ellipses, parabolas, mathematically defined surface patterns, or random or pseudo-random patterns. Many other shapes of valleys may be formed. Exemplary diamond turning machines and methods for producing discontinuous or non-uniform surface structures may include and utilize a Fast Tool Servo (FTS) as described in the following patents: for example, PCT publication WO 00/48037 published on 8/17/2000; U.S. Pat. Nos. 7,350,442(Ehnes et al) and 7,328,638(Gardiner et al); and U.S. patent publication 2009/0147361(Gardiner et al), each of which is incorporated by reference herein in its entirety.

In some embodiments, the plurality of nanostructures may be formed by shaping the extruded material or layer 208 with a microreplication tool that also has a layer of nanostructured particulate plating for imprinting. Electrodeposition, or more specifically electrochemical deposition, can also be used to generate various surface structures, including nanostructures, to form microreplication tools. The tool may be made using a two-part plating process, wherein a first plating process may form a first metal layer having a first major surface, and a second plating process may form a second metal layer on the first metal layer. The second metal layer may have a second major surface having an average roughness that is less than an average roughness of the first major surface. The second major surface may serve as a structured surface for the tool. A replica of this surface can then be made in the major surface of the optical film to provide light diffusing properties. One example of an electrochemical deposition technique is described in the following U.S. patent applications: U.S. serial No. 62/446821, PCT publication WO 2018/130926 (published on 2018, 7/19) entitled "Faceted Micro-structured Surface", filed 2017, 1/16 (Derks et al), the disclosures of which are incorporated herein by reference in their entirety.

Fig. 4 shows a cross-section 400 of a layer 408 having an antireflective surface 402. The antireflective surface 402 may be similar to the antireflective surface 202, e.g., the microstructures 218, 418 of the layers 208, 408 may have the same or similar dimensions, and may also form a skipped, toothed rib pattern of alternating micro-peaks 420 and micro-spaces 422. The antireflective surface 402 differs from the surface 202 in that, for example, the nanostructures 520 may include nano-sized masking elements 522.

The nanostructures 520 may be formed using masking elements 522. For example, the masking elements 522 may be used in a subtractive manufacturing process, such as Reactive Ion Etching (RIE), to form the nanostructures 520 having the surface 402 of the microstructures 418. Methods of making nanostructures and nanostructured articles may involve depositing a layer (such as layer 408) to a major surface of a substrate by plasma chemical vapor deposition from a gaseous mixture while substantially simultaneously etching the surface with a reactive species. The method may include providing a substrate; a first gaseous species capable of depositing a layer onto a substrate when a plasma is formed is mixed with a second gaseous species capable of etching the substrate when the plasma is formed, thereby forming a gaseous mixture. The method can include forming a gas mixture into a plasma and exposing a surface of a substrate to the plasma, wherein the surface can be etched and a layer can be deposited substantially simultaneously on at least a portion of the etched surface, thereby forming nanostructures.

The substrate may be a (co) polymeric material, an inorganic material, an alloy, a solid solution, or a combination thereof. The deposited layer may comprise a reaction product of plasma chemical vapor deposition using a reaction gas comprising a compound selected from the group consisting of organosilicon compounds, metal alkyl compounds, metal isopropoxy compounds, metal acetylacetonate compounds, metal halides, and combinations thereof. Nanostructures of high aspect ratio can be prepared and optionally have random dimensions in at least one dimension, even in three orthogonal dimensions.

In some embodiments of a method of forming the antireflective surface 402, a layer 408 having a series of microstructures 418 disposed on the surface 402 of the layer may be provided. The series of microstructures 418 can include a series of alternating micro-peaks 420 and micro-spaces 422.

A series of nano-sized masking elements 522 may be disposed over at least the micro-spaces 422. Surface 402 of layer 408 may be exposed to a reactive ion etch to form a plurality of nanostructures 518 on the surface of the layer comprising a series of nanopeaks 520. Each nanopeak 520 may include a masking element 522 and a column 560 of layer material between the masking element 522 and the layer 408.

Masking element 522 may be formed of any suitable material that is more resistant to the RIE effect than the material of layer 408. In some embodiments, the masking element 522 comprises an inorganic material. Non-limiting examples of inorganic materials include silica and silicon dioxide. In some embodiments, the masking elements 522 are hydrophilic. Non-limiting examples of hydrophilic materials include silica and silicon dioxide.

As used herein, the term "maximum diameter" refers to the longest dimension based on a straight line through an element having any shape.

The masking elements 522 may be nano-sized. Each masking element 522 may define a maximum diameter 542. In some embodiments, the maximum diameter of the masking elements 522 may be at most 1000 nanometers (in some embodiments, at most 750 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even at most 100 nanometers).

The maximum diameter 542 of each masking element 522 may be described relative to the peak height 440 of the corresponding peak 420. In some embodiments, the corresponding micro-peak height 440 is at least 10 times (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) the maximum diameter 542 of the masking element 522.

Each nanopeak 520 may define a height 522. The height 522 may be defined between the baseline 550 and the apex 548 of the masking element 522.

Fig. 5A and 5B show lines 600 and 620 representing cross-sectional profiles of different forms of peaks 602, 622 for any antireflective surface (such as surfaces 202, 402), which may be micro-peaks of a microstructure or nano-peaks of a nanostructure. As mentioned, the structure need not be strictly triangular in shape.

Line 600 shows that a first portion 604 (top portion) of a peak 602 including an apex 612 may have a generally triangular shape, while an adjacent side 606 may be curved. In some embodiments, as shown, the sides 606 of the peak 602 may not have sharper turns when transitioning into the space 608. A boundary 610 between the side 606 of the peak 602 and the space 608 may be defined by a threshold slope of the line 600, as discussed herein, e.g., with respect to fig. 2A-2C and 3.

Space 608 may also be defined in terms of height relative to height 614 of peak 602. A height 614 of peak 602 may be defined between one of boundaries 610 and vertex 612. The height of the space 608 may be defined between the lowest point of the bottom 616 or the space 608 and one of the boundaries 610. In some embodiments, the height of space 608 can be at most 40% (in some embodiments, at most 30%, 25%, 20%, 15%, 10%, 5%, 4%, 3%, or even at most 2%) of the height 614 of peak 602. In some embodiments, the height of space 608 is at most 10% (in some embodiments, at most 5%, 4%, 3%, or even at most 2%) of the height 614 of peak 602.

Line 620 shows that a first portion 624 (top portion) of the peak 620, including the apex, may have a generally rounded shape without sharp turns between adjacent sides 626. Apex 632 may be defined as the highest point of structure 620, e.g., where the slope changes from positive to negative. Although the first portion 624 (top portion) may be rounded at the apex 632, the peak 620 may still define an angle between the first average slope and the second average slope, such as angle a (see fig. 3).

The boundary 630 between the sides 626 of the peak 620 and the space 628 may be defined by a sharper turn, for example. The boundary 630 may also be defined by a slope or relative height, as described herein.

As shown in fig. 10-13, the antireflective surface may be discontinuous, intermittent, or non-uniform. For example, the antireflective surface can also be described as comprising micro-pyramids with micro-spaces surrounding the micro-pyramids (see fig. 12 and 13).

Fig. 10 shows a first anti-reflective surface 1001 defined at least in part by a non-uniform microstructure 1010. For example, if the anti-reflective surface 1001 is viewed in the yz plane (similar to fig. 2B), at least one of the micro-peaks 1012 may have a non-uniform height from the left side to the right side of the view, which may be contrasted with fig. 2B, which shows micro-peaks 220 having a uniform height from the left side to the right side of the view. In particular, at least one of the height or shape of the micro-peaks 1012 defined by the microstructures 1010 may be non-uniform. The micro-peaks 1012 are separated by micro-spaces (not shown in this perspective), similar to the micro-spaces 222 (fig. 2A and 2C) of other surfaces described herein, such as surface 202.

Fig. 11 shows a second anti-reflective surface 1002 having discontinuous microstructures 1020. For example, if the antireflective surface 1002 is viewed in the yz plane (similar to fig. 2B), more than one microfeak 1022 may be shown separated by microstructures 1020, which may be contrasted with fig. 2B, which shows microfeaks 220 that extend continuously from the left side to the right side of the view. In particular, the micro-peaks 1022 of microstructures 1020 may be surrounded by micro-spaces 1024. The micro-peaks 1022 may each have a semi-dome shape. For example, the semi-dome-like shape may be hemispherical, semi-ovoid, semi-prolate spherical, or semi-oblate spherical. The edge 1026 of the base of each microfeak 1022 extending around each microfeak can be circular in shape (e.g., circular, oval, or rounded rectangle). The shape of the micro-peaks 1022 may be uniform, as depicted in the illustrated embodiment, or may be non-uniform.

Fig. 12 and 13 are perspective views of a first portion 1004 (fig. 12) and a second portion 1005 (fig. 13) of a third antireflective surface 1003 with discontinuous microstructures 1030. Both in perspective view. Fig. 12 shows more of the "front" side of microstructure 1030 closer to the 45 degree angle, while fig. 13 shows some of the "back" side of the microstructure closer to the apex angle.

A micro-peak 1032 of the microstructure 1030 surrounded by the micro-spaces 1034 may have a pyramid-like shape (e.g., a micro-pyramid). For example, the pyramid-like shape may be a rectangular pyramid or a triangular pyramid. The sides 1036 of the pyramid shape can be non-uniform in shape or area (as shown in the illustrated embodiment), or can be uniform in shape or area. The pyramid-shaped edges 1038 may be non-linear (as shown in the illustrated embodiment) or may be linear. The total volume of each microfeak 1032 may be non-uniform, as depicted in the illustrated embodiment, or may be uniform.

Fig. 15 shows a multilayer film with skipped tooth microstructures 1505 having micro spaces 1506 and nanostructures on the micro spaces. A multilayer film may be advantageous because its physical and chemical properties on the top surface of the film are different from those on the bottom surface of the film. For example, highly fluorinated polymers are beneficial for stain, chemical and soil resistance, but do not inherently adhere well to other polymers or adhesives. The first fluoropolymer layer 1501 having a high content of Tetrafluoroethylene (TFE) has a relatively high fluorine content and thus may be beneficial as a microstructured surface layer in articles described herein. The second fluoropolymer layer 1502 can have a lower content of TFE 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 1503 layer includes sufficient VDF, it will adhere well to the non-fluorinated polymer layer 1504, such as acrylate polymers and even urethane polymers. Multilayer fluoropolymer films useful for antireflective surface structured films having a highly fluorinated top surface layer and a less fluorinated bottom surface layer are described in PCT publication WO2017/172564a2, published in 2017, 10, month 5, which is incorporated herein by reference in its entirety.

In some embodiments, the multilayer fluoropolymer film can be coextruded and simultaneously extrusion microreplicated, with the skipped tooth microstructures having microspaces. For example, a first fluoropolymer available from 3M under the trade designation "3 MDYNEON THV 815" can be coextruded as a first layer with a second fluoropolymer available from 3M under the trade designation "3 MDYNEON THV 221" (as a second layer) and a third fluoropolymer available from 3M under the trade designation "3M dynoon PVDF 6008" (as a third layer). Optionally, a fourth layer of PMMA available, for example, under the trade designation "VO 44" from Arkema, Bristol, PA or CoPMMA available under the trade designation "kurarit LA 4285" from korea limited, Osaka, Japan, or a polymer blend thereof, may be coextruded with the three fluoropolymer layers. The multilayer fluoropolymer coextrusion process can provide a highly fluorinated top antireflective surface structured layer and a bottom layer with little or no fluorine content.

Uv stabilization with uv absorbers (UVA) and hindered amine light stabilizers (HAL) can intervene to prevent photooxidative degradation of PET, PMMA and CoPMMA. UVAs for incorporation into PET, PMMA or CoPMMA optical layers include benzophenones, benzotriazoles and benzothiazolines. Exemplary UVAs for incorporation into PET, PMMA, or CoPMMA optical layers are available under the trade names "TINUVIN 1577" or "TINUVIN 1600", either from BASF Corporation, Florham Park, NJ. Typically, UVA is incorporated into the polymer at a concentration of 1 to 10% by weight. Exemplary HALs for incorporation into PET, PMMA, or CoPMMA optical layers are available under the tradenames "CHIMMASORB 944" or "TINUVIN 123", either of which are available from BASF Corporation. Typically, the HAL is incorporated into the polymer at 0.1 to 1.0 wt%. A 10:1 ratio of UVA to HAL may be used.

UVA and HAL may also be incorporated into the fluoropolymer surface layer or into the fluoropolymer layer below the surface layer. Exemplary UVA oligomers compatible with fluoropolymers and fluoropolymer blends are described in U.S. patent 9,670,300(Olson et al) and U.S. patent publication 2017/0198129(Olson et al), which are incorporated herein by reference in their entirety.

Other uv blocking additives may be included in the fluoropolymer surface layer. Non-pigmented particulate zinc oxide and titanium oxide may also be used as UV blocking additives in the fluoropolymer surface layer. The nano-sized particles of zinc oxide and titanium oxide will reflect or scatter ultraviolet light while being transparent to visible and near infrared light. These small zinc oxide and titanium oxide particles having a particle size in the range of 10 nm to 100 nm, which reflect ultraviolet light, are commercially available from Kobo Products inc (Kobo Products inc., South Plainfield, NJ), South pope.

Antistatic additives may also be used for incorporation into the fluoropolymer surface layer or into the optical layer to reduce the undesirable attraction of dust, dirt, and debris. Ionic antistatic agents (e.g., available under the trade designation "3M IoNIC LIQUIDANTI-STAT FC-4400" or "3M IoNIC LIQUID ANTI-STAT FC-5000" from 3M company (3M company)) may be incorporated into the PVDF fluoropolymer layer to provide static dissipation. Antistatic additives for PMMA and CoPMMA optical polymer layers may be supplied under the trade designation "STATISTE" from Lubrizol engineered Polymers, Brecksville, Ohio. Additional antistatic additives for PMMA and CoPMMA optical polymer layers may be provided under the trade designation "PELESTAT" available from sanyo chemical Industries, Tokyo, Japan. Optionally, the antistatic properties may have transparent conductive coatings such as: indium Tin Oxide (ITO), fluorine doped tin oxide (FTO), aluminum doped zinc oxide (AZO), metal nanowires, carbon nanotubes, or graphene thin layers, any of which may be disposed or coated onto one of the layers of the antireflective surface structured film described herein.

Illustrative embodiments

While various aspects of antireflective surfaces are described, various exemplary combinations are also described to further illustrate various combinations of microstructures and nanostructures that may be used in certain applications, some of which are described herein. As used herein, "comprising any X embodiment" is meant to include any embodiment comprising the name X (e.g., any a embodiment refers to any embodiment A, A1, a2, A5a, etc., and any A5 embodiment refers to any embodiment A5, A5a, A5b, etc.).

In an exemplary embodiment a, an article includes a layer defining an antireflective surface extending along an axis. A plane containing the axis defines a cross-section of the layer and intersects the surface to define a line delineating the cross-sectional profile of the surface. The layer includes a series (i.e., elements arranged sequentially in at least one dimension) of microstructures (i.e., microstructures having a height and a width both in the range of 1 micron to 1000 microns) at least partially defined by the line. The line defines a series of alternating micro-peaks and micro-spaces along the axis (in some embodiments, the micro-spaces between pairs of micro-peaks, or vice versa; in some embodiments, at least one pair of micro-peaks may not include a micro-space therebetween). Each micro-space defines a maximum absolute slope that defines an angle of at most 30 degrees (in some embodiments, at most 25 degrees, 20 degrees, 15 degrees, 10 degrees, 5 degrees, 4 degrees, 3 degrees, 2 degrees, and even at most 1 degree) from the axis. Each of the microflakes includes a first microfracture defining a first average slope and a second microfracture defining a second average slope. The angle formed between the first average slope and the second average slope is at most 120 degrees (in some embodiments, at most 110 degrees, 100 degrees, 90 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 20 degrees, or even at most 10 degrees). The layer also includes a plurality of nanostructures (i.e., nanostructures that are both less than 1 micron in height and width) at least partially defined by the lines. The line defines at least one series of nanopeaks disposed along an axis on at least a microspace. Each nanopeak has a height (i.e., from a baseline of the nanopeak to an apex of the nanopeak), and each corresponding nanopeak has a height that is at least 10 times (in some embodiments, at least 25 times, 50 times, 75 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) the height of the nanopeak (i.e., the nanopeak or the nanopeak on the microspace corresponding to the nanopeak).

In exemplary embodiment B, the article includes a layer defining an antireflective surface extending along an axis. A plane containing the axis defines a cross-section of the layer and intersects the surface to define a line delineating the cross-sectional profile of the surface. The layer includes a series of microstructures at least partially defined by lines. The line defines a series of alternating micro-peaks and micro-spaces along the axis. The boundary between each adjacent microfeak and the micro-space includes at least one of a bend of a line (i.e., a point at the sharpest curve or a point of change in direction of a straight line as compared to adjacent portions) or an inflection point (e.g., a point of a line where the direction of curvature changes). The layer also includes a plurality of nanostructures at least partially defined by the lines. The line defines at least one series of nanopeaks disposed along an axis on at least a microspace. Each nanopeak has a height (i.e., from a baseline of the nanopeak to an apex of the nanopeak), and each corresponding nanopeak has a height that is at least 10 times (in some embodiments, at least 25 times, 50 times, 75 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) the height of the nanopeak (i.e., the nanopeak or the nanopeak on the microspace corresponding to the nanopeak).

In exemplary embodiment a1, an article of any a embodiment is included wherein the first average slope of the micro-peaks is positive and the second average slope of the micro-peaks is negative.

In an exemplary embodiment a2, an article of any a embodiment is included wherein the absolute value of the first average slope of the microform is equal to the absolute value of the second average slope of the microform.

In exemplary embodiment a3, articles of any of the a or B embodiments are included in which the width of each microspace is at least 10% (in some embodiments, at least 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, or even at least 90%) of the corresponding microspeak distance (i.e., the distance between the nearest pair of microspeaks measured at each vertex).

In exemplary embodiment a4, an article of any of the a or B embodiments is included, wherein the width of the micro-spaces is at least 10 microns (in some embodiments, at least 20 microns, 25 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 75 microns, 80 microns, 90 microns, 100 microns, 125 microns, 150 microns, 200 microns, or even at least 250 microns).

In exemplary embodiment a5, an article of any of the a or B embodiments is included wherein the micro-peak distance between the micro-peaks is at least 1 micron (in some embodiments, at least 2 microns, 3 microns, 4 microns, 5 microns, 10 microns, 25 microns, 50 microns, 75 microns, 100 microns, 150 microns, 200 microns, 250 microns, or even at least 500 microns).

In exemplary embodiment a6, articles of either a or B embodiment are included in which the micro-peak distance between the micro-peaks is at most 1000 microns (in some embodiments, at most 900 microns, 800 microns, 700 microns, 600 microns, 500 microns, 400 microns, 300 microns, 250 microns, 200 microns, 150 microns, 100 microns, or even at most 50 microns).

In exemplary embodiment a7, an article of any of the a or B embodiments is included wherein the height of the microfeaks is at least 10 microns (in some embodiments, at least 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 75 microns, 80 microns, 90 microns, 100 microns, 150 microns, 200 microns, or even at least 250 microns).

In an exemplary embodiment A8, an article of any one of the a or B embodiments is included, wherein each nanopeak includes a first nanopartide defining a first average slope and a second nanopartide defining a second average slope, wherein an angle formed between the first average slope of the nanopeak and the second average slope of the nanopeak is at most 120 degrees (in some embodiments, at most 110 degrees, 100 degrees, 90 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 at most 10 degrees).

In an exemplary embodiment A8a, an article of embodiment A8 is included wherein an absolute value of a first average slope of the nanopeak is different from an absolute value of a second average slope of the nanopeak.

In an exemplary embodiment a9, an article of any of the a or B embodiments is included, wherein the plurality of nanostructures is further disposed on the micro-peak.

In an exemplary embodiment a10, an article of any of the a or B embodiments is included, wherein each nanopeak defines a nanopeak distance, and the corresponding nanopeak defines a nanopeak distance that is at least 10 times (in some embodiments, at least 25 times, 50 times, 75 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) the nanopeak distance.

In exemplary embodiment a11, articles of any of the a or B embodiments are included wherein the nanopeak distance between nanopeaks is at most 1 micrometer (in some embodiments, at most 750 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even at most 100 nanometers).

In exemplary embodiment a12, articles of any of the a or B embodiments are included wherein the nanopeak distance between nanopeaks is at least 1 nanometer (in some embodiments, at least 2 nanometers, 3 nanometers, 4 nanometers, 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 exemplary embodiment a13, an article according to any of embodiments a or B is included, wherein the layer defining the antireflective surface comprises at least one of a fluoropolymer, a polyolefin polymer, or a uv stabilizing material.

In exemplary embodiment a14, an article of any of the a or B embodiments is included, wherein the nanopeak includes at least one masking element (in some embodiments, the masking element includes an inorganic material).

In exemplary embodiment a14a, an article of embodiment a14 is included wherein the masking elements have a diameter of at most 1 micrometer (in some embodiments, at most 750 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even at most 100 nanometers).

In exemplary embodiment a14b, an article of any of the a14 embodiments is included, wherein the masking element is hydrophilic.

In exemplary embodiment a15, an article of any of the embodiments a is included, wherein the micro-peaks are non-uniform in at least one of height or shape.

In an exemplary embodiment a16, the article of any of the a or B embodiments is included, further comprising a uv stable adhesive coupled to a side of the layer opposite the antireflective surface.

In exemplary embodiment a16a, an article of embodiment a15 is included in which the UV stable adhesive is self-wetting to the glass (i.e., can be laid down on the glass without the generation of bubbles).

In exemplary embodiment C, a method of forming an article having a layer defining an antireflective surface comprises forming a series of microstructures on a surface of the layer. The series of microstructures includes a series of alternating micro-peaks and micro-spaces along an axis. The method also includes disposing a series of nanoscale masking elements along the axis over at least the micro-space. The masking elements define a maximum diameter (i.e., the longest dimension based on a straight line passing through any suitably shaped masking element), and the height of the corresponding micro-peaks is at least 10 times (in some embodiments, at least 25 times, 50 times, 75 times, 100 times, 200 times, 300 times, 400 times, 500 times, 750 times, or even at least 1000 times) the maximum diameter of the masking elements. The method also includes exposing the surface of the layer to reactive ion etching to form a plurality of nanostructures on the surface of the layer, the nanostructures including a series of nanopeaks along an axis. Each nanopeak includes a masking element and a pillar between the masking element and the layer.

In an exemplary embodiment C1, the method according to any of the C embodiments is included, further comprising disposing a series of masking elements on the microfeaks.

In an exemplary embodiment C2, the method of any of the embodiments C is included, wherein the maximum diameter of the masking element is at most 1 micron (in some embodiments, at most 750 nanometers, 500 nanometers, 400 nanometers, 300 nanometers, 250 nanometers, 200 nanometers, 150 nanometers, or even at most 100 nanometers).

In exemplary embodiment D, a method of forming an article having a layer defining an antireflective surface comprises extruding a hot melt material having a uv stabilizing material. The method also includes shaping the extruded material with a microreplication tool having a mirror image of the series of microstructures to form a series of microstructures on a surface of the layer. The series of microstructures includes a series of alternating micro-peaks and micro-spaces along an axis. The method also includes forming a plurality of nanostructures on a surface of the layer at least over the micro-spaces. The plurality of nanopeaks includes at least one series of nanopeaks (e.g., along an axis).

In exemplary embodiment D1, the method of any one of embodiments D, wherein forming the plurality of nanostructures comprises exposing the surface to reactive ion etching.

In exemplary embodiment D2, the method of any D embodiment, wherein forming the plurality of nanostructures comprises shaping the extruded material with a microreplication tool that also has ion etched diamond.

In exemplary embodiment D3, the method of any D embodiment, wherein forming the plurality of nanostructures comprises shaping the extruded material with a microreplication tool that also has a nanostructured particulate electroplated layer.