Low reflectivity removable lens stack

Abstract

A removable lens stack includes a substrate layer and one or more removable lens layers. The substrate layer may include a substrate and a moth-eye coating on a first and second side of the substrate. A first removable lens layer may include a substrate and an acrylic or fluoropolymer coating on a first side of the substrate, and the first removable lens layer may be stacked over the substrate layer such that the second side of the substrate faces the first side of the substrate layer. A second removable lens layer may include a substrate and an acrylic or fluoropolymer coating on a first side of the substrate, and the second removable lens layer may be stacked over the first removable lens layer such that the second side of the substrate faces the first side of the substrate layer. The acrylic or fluoropolymer coating may include a hard coating.

Description

[0001] Cross-reference to related applications

[0002] This application is a continuation-in-part of U.S. Patent Application No. 18 / 315,394, filed May 10, 2023, which is a continuation-in-part of U.S. Patent Application No. 18 / 167,673, filed February 10, 2023, which was granted U.S. Patent No. 11,709,296 on July 25, 2023; and U.S. Patent Application No. 18 / 315,394 is a continuation-in-part of U.S. Patent Application No. 17 / 655,328, filed March 17, 2022, which was granted U.S. Patent No. 17 / 655,328 on April 11, 2023. 11,624,859; U.S. Patent Application No. 18 / 315,394 is a continuation-to-file of U.S. Patent Application No. 17 / 386,304, filed July 27, 2021, which was granted on April 19, 2022, as U.S. Patent No. 11,307,329. The contents of all the above applications are expressly incorporated herein by reference.

[0003] Statement regarding federally sponsored research or development

[0004] not applicable Background Technology

[0005] Maintaining visibility is crucial in various environments where protective eyewear such as goggles, face shields, and visors are used, especially when debris accumulates on the glasses. For example, in off-road sports like motocross, participants need to ensure visibility of the track when dirt, insects, and other debris accumulate on goggles or helmet visors. Similarly, in operating room environments, debris can obstruct the vision of surgeons or other personnel during procedures. To address these needs, peel-off films are typically used, applied alone or in laminated layers to goggle lenses, face shields, or visors. When debris accumulates on the outermost peel-off film or the outermost layer is damaged, the wearer simply peels it off to reveal the new film underneath.

[0006] To ensure visual sensitivity through such stacked lenses, internal reflections need to be minimized. A promising technique for reducing reflections is called moth-eye (ME) coating, which effectively eliminates the refractive index interface between the lens and air by providing a micro-protruding pattern that mimics the anti-reflective properties of a moth's eye. Unfortunately, in the case of lens stacking, the adhesive used between the layers often fills around the protrusions of the ME coating, significantly increasing the peel strength of each layer (e.g., to 650 to 1,070 g / in). This renders the stack unusable because the layers are difficult to peel off, and the force required to remove a layer may exceed the tensile strength of the lens material. Summary of the Invention

[0007] This disclosure contemplates various apparatuses and methods to overcome the deficiencies of related technologies. One aspect of an embodiment of this disclosure is a removable lens stack. The removable lens stack may include a substrate layer comprising a base material having a first side and a second side opposite to the first side, the substrate layer further comprising a moth-eye coating on the first side of the base material. The removable lens stack may also include one or more removable lens layers, each removable lens layer comprising a base material having a first side and a second side opposite to the first side, a moth-eye coating on the first side of the base material, and a fluoropolymer coating on the second side of the base material. The one or more removable lens layers may be stacked over the base layer such that the second side of the base material of each removable lens layer faces the base layer and the first side of the base material of the one or more removable lens layers immediately preceding it. Each fluoropolymer coating may be molded to conform to the moth-eye coating of the immediately preceding layer.

[0008] In each of the one or more removable lens layers and substrate layers, the moth-eye coating may contain a polymer.

[0009] In each of the one or more removable lens layers and substrate layers, the moth-eye coating can define a raised pattern with a half-wave pitch.

[0010] In each of the one or more removable lens layers and substrate layers, the moth-eye coating can define a raised pattern with a half-wave height.

[0011] In each of the one or more removable lens layers and substrate layers, the moth-eye coating can define a cone pattern.

[0012] The base layer may also include a moth-eye coating located on the second side of the substrate.

[0013] In each of the one or more removable lens layers and substrate layers, the substrate may comprise polyethylene terephthalate (PET).

[0014] The removable lens stack may include an adhesion process between the substrate and the moth-eye coating in each of the one or more removable lens layers and the substrate layer. The adhesion process may include a pressure-sensitive adhesive.

[0015] The removable lens stack may include an adhesion process between a substrate and a fluoropolymer coating in each of the one or more removable lens layers. The adhesion process may include a pressure-sensitive adhesive.

[0016] The peel strength of each of the one or more removable lens layers may be less than 100 grams per inch. The peel strength of each of the one or more removable lens layers may be between 15 and 50 grams per inch, and more particularly, between 15 and 30 grams per inch.

[0017] The visible light transmittance (VLT) of the removable lens stack can be greater than 95%, and more specifically, greater than 98%.

[0018] Another aspect of this disclosure is a method of manufacturing a removable lens stack. The method may include providing a substrate layer comprising a substrate having a first side and a second side opposite to the first side, the substrate layer further comprising a moth-eye coating on the first side of the substrate. The method may further include stacking one or more removable lens layers over the substrate layer, each removable lens layer comprising a substrate having a first side and a second side opposite to the first side, a moth-eye coating on the first side of the substrate, and a fluoropolymer coating on the second side of the substrate. The one or more removable lens layers may be stacked over the substrate layer such that the second side of the substrate of each removable lens layer faces the substrate layer and the first side of the substrate of the one or more removable lens layers immediately preceding it. The method may further include laminating the stacked one or more removable lens layers to the substrate layer, each fluoropolymer coating being shaped to conform to the moth-eye coating of the immediately preceding layer.

[0019] Lamination can include laminating one or more stacked removable lens layers onto a substrate layer under pressure and at a temperature below 40°C.

[0020] The method may include applying a corona treatment between the substrate and the moth-eye coating in each of the one or more removable lens layers.

[0021] The method may include applying a corona treatment between the substrate and the fluoropolymer coating in each of the one or more removable lens layers.

[0022] Another aspect of this disclosure is a removable lens stack comprising a substrate, a first removable lens layer, and a second removable lens layer. The substrate may include a substrate and a moth-eye coating on a first side of the substrate. The first removable lens layer may include a substrate, a single or multiple interference antireflective coating on the first side of the substrate, and a fluoropolymer coating on a second side of the substrate opposite to the first side. The first removable lens layer may be stacked over the substrate such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the substrate, and the fluoropolymer coating is shaped to conform to the moth-eye coating. The second removable lens layer may include a substrate, a single or multiple interference antireflective coating on the first side of the substrate, and an acrylic or polyurethane adhesive on the second side of the substrate opposite to the first side. The second removable lens layer may be stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

[0023] The moth-eye coating may contain a polymer. The moth-eye coating may define a raised pattern with a half-wave pitch. The moth-eye coating may define a raised pattern with a half-wave height. The moth-eye coating may define a conical pattern.

[0024] The base layer may include a moth-eye coating located on a second side of the substrate opposite to the first side.

[0025] In each of the substrate layer, the first removable lens layer, and the second removable lens layer, the substrate may comprise polyethylene terephthalate (PET).

[0026] The removable lens stack may further include a third removable lens layer, comprising a substrate, a single or multiple layers of interference antireflective coating on a first side of the substrate, and an acrylic or polyurethane adhesive on a second side of the substrate opposite to the first side. The third removable lens layer may be stacked over the second removable lens layer such that the second side of the substrate of the third removable lens layer faces the first side of the substrate of the second removable lens layer. The removable lens stack may further include a fourth removable lens layer, comprising a substrate, a single or multiple layers of interference antireflective coating on a first side of the substrate, and an acrylic or polyurethane adhesive on a second side of the substrate opposite to the first side. The fourth layer may be stacked over the third removable lens layer such that the second side of the substrate of the fourth removable lens layer faces the first side of the substrate of the third removable lens layer.

[0027] The peel strength of the first removable lens layer can be less than 100 grams per inch. The peel strength of the first removable lens layer can be between 15 and 50 grams per inch. The peel strength of the first removable lens layer can be between 15 and 30 grams per inch.

[0028] The visible light transmittance (VLT) of a removable lens stack can be greater than 95%. The VLT of a removable lens stack can be greater than 98%.

[0029] Another aspect of this disclosure is a method of manufacturing a removable lens stack. The method includes providing a substrate layer comprising a base material and a moth-eye coating on a first side of the base material, stacking a first removable lens layer over the substrate layer, the first removable lens layer comprising a base material, a single or multiple interference antireflective coating on the first side of the base material, and a fluoropolymer coating on a second side of the base material opposite to the first side. The first removable lens layer may be stacked over the substrate layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the substrate layer. The method may further include laminating the stacked first removable lens layer to the substrate layer, wherein the fluoropolymer coating is shaped to conform to the moth-eye coating. The method may further include stacking a second removable lens layer over the first removable lens layer, the second removable lens layer comprising a base material, a single or multiple interference antireflective coating on a first side of the base material, and an acrylic or polyurethane adhesive on a second side of the substrate opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

[0030] Lamination can include laminating a stacked first removable lens layer onto a substrate layer under pressure and at a temperature below 40°C. Lamination can be performed before stacking a second removable lens layer on top of the first removable lens layer.

[0031] The method may also include applying corona treatment between the substrate of the base layer and the moth-eye coating and / or between the substrate of the first removable lens layer and the fluoropolymer coating.

[0032] The method may further include stacking a third removable lens layer over a second removable lens layer. The third removable lens layer includes a substrate, a single or multiple layers of interference antireflective coating on a first side of the substrate, and an acrylic or polyurethane adhesive on a second side of the substrate opposite to the first side. The third removable lens layer may be stacked over the second removable lens layer such that the second side of the substrate of the third removable lens layer faces the first side of the substrate of the second removable lens layer. The method may further include stacking a fourth removable lens layer over the third removable lens layer. The fourth removable lens layer includes a substrate, a single or multiple layers of interference antireflective coating on a first side of the substrate, and an acrylic or polyurethane adhesive on a second side of the substrate opposite to the first side. The fourth removable lens layer may be stacked over the third removable lens layer such that the second side of the substrate of the fourth removable lens layer faces the first side of the substrate of the third removable lens layer.

[0033] Another aspect of this disclosure is a removable lens stack including a substrate layer, a first removable lens layer, and a second removable lens layer. The substrate layer may include a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. The first removable lens layer may include a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked over the substrate layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the substrate layer. The second removable lens layer may include a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

[0034] The acrylic coatings of both the first and second removable lens layers may include a hard acrylic coating. The hard acrylic coating may contain silica beads. The first removable lens layer may include a fluoropolymer coating on a second side of the substrate, the fluoropolymer coating being molded to adhere to a moth-eye coating on a first side of the substrate. The second removable lens layer may include an acrylic adhesive on a second side of the substrate. The second removable lens layer may also include a polyurethane adhesive on a second side of the substrate.

[0035] Another aspect of this disclosure is a removable lens stack including a substrate layer and a first removable lens layer. The substrate layer may include a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. The first removable lens layer may include a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked over the substrate layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the substrate layer.

[0036] The acrylic coating may include a hard acrylic coating. The hard acrylic coating may contain silica beads. A first removable lens layer may include a fluoropolymer coating on a second side of a substrate, the fluoropolymer coating being molded to adhere to a moth-eye coating on a first side of the substrate of the base layer. A removable lens stack may include a second removable lens layer, the second removable lens layer including a substrate, an acrylic coating on a first side of the substrate, and an acrylic adhesive on a second side of the substrate opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer. A removable lens stack may include a second removable lens layer, the second removable lens layer including a substrate, an acrylic coating on a first side of the substrate, and a polyurethane adhesive on a second side of the substrate opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

[0037] Another aspect of this disclosure is a removable lens stack including a substrate layer and a first removable lens layer. The substrate layer may include a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. The first removable lens layer may include a substrate and a fluoropolymer coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked over the substrate layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the substrate layer.

[0038] The fluoropolymer coating of the first removable lens layer may include a fluoropolymer hard coating. The fluoropolymer hard coating may contain silica beads. The first removable lens layer may include a fluoropolymer coating on a second side of a substrate, the fluoropolymer coating on the second side of the substrate of the first removable lens layer being shaped to conform to a moth-eye coating on a first side of the substrate of a base layer. The removable lens stack may include a second removable lens layer, the second removable lens layer including a substrate and a fluoropolymer coating on a first side of the substrate, the substrate having a second side opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer. The second removable lens layer may include an acrylic adhesive on the second side of the substrate. The second removable lens layer may include a polyurethane adhesive on the second side of the substrate. The fluoropolymer coating of the second removable lens layer may include a fluoropolymer hard coating. Attached Figure Description

[0039] The above and other features and advantages of the various embodiments disclosed herein will be better understood from the following description and drawings, in which the same reference numerals always denote the same parts, and wherein: Figure 1 This is a cross-sectional view of the substrate layer and two removable lens layers of a removable lens stack according to one embodiment of this disclosure; Figure 2 For having Figure 1 Cross-sectional view of the removable lens stack of layers; Figure 3 A cross-sectional view of the substrate layer and the removable lens layer of a removable lens stack according to another embodiment of this disclosure; Figure 4 For having Figure 3 Cross-sectional view of the removable lens stack of layers; Figure 5 This is a cross-sectional view of the substrate layer and the removable lens layer of a removable lens stack according to another embodiment of this disclosure; and Figure 6 For having Figure 5 Cross-sectional view of the removable lens stack of layers. Detailed Implementation

[0040] This disclosure covers various embodiments of removable lens stacks and methods of manufacturing thereof. The detailed description set forth below with reference to the accompanying drawings is intended as a description of several currently contemplated embodiments and is not intended to represent the only form in which the invention of this disclosure can be developed or used. This description sets forth functions and features associated with the illustrated embodiments. However, it should be understood that the same or equivalent functions can be achieved by different embodiments, which are also intended to be covered by the scope of this disclosure. It is further understood that the use of relational terms such as “first” and “second” is only for distinguishing one entity from another and does not necessarily require or imply any actual such relationship or order between these entities.

[0041] Figure 1 This is a cross-sectional view of the base layer 100 and two removable lens layers 200, which can be stacked together to form a shape such as... Figure 2 The removable lens stack 10 is shown in cross-section. For example, the base layer 100 of the removable lens stack 10 can be fixed to a surface such as a goggle lens or face shield, or a transparent window on a surgical helmet, hood, or gown, or its periphery can be attached to a frame so that the removable lens stack 10 itself acts as a lens, face shield, mask, etc. (i.e., it does not need to be fixed to a surface). Figure 1 and Figure 2The example shows two removable lens layers 200 stacked on a substrate layer 100 to form a removable lens stack 10. However, it is conceivable that there may be more than two removable lens layers 200 or only a single removable lens layer 200. As shown, each removable lens layer 200 may include a substrate 210 and a moth-eye coating 220 located on a first side 212 of the substrate 210. The substrate layer 100 may also include a substrate 110 and a moth-eye coating 120a located on a first side 112 of the substrate 110, and optionally a moth-eye coating 120b located on a second side 114 opposite to the first side 112. Due to the presence of the moth-eye coatings 120a, 120b, and 220, the removable lens stack 10 can achieve extremely low reflectivity, thereby exhibiting a visible light transmittance (VLT) greater than 95% or, in some cases, greater than 98% (e.g., >99% when the reflectivity is less than 1%).

[0042] Unlike conventional removable lenses, each removable lens layer 200 may additionally include a fluoropolymer coating 230 located on a second side 214 of the substrate 210 opposite its first side 212. Therefore, when the removable lens layers 200 are stacked on top of the substrate 100 and the second side 214 of each substrate 210 faces the first side 112, 212 of the adjacent preceding substrate 110, 210 (which, depending on the specific circumstances, may be the substrate 210 adjacent to the preceding removable lens layer 200, or the substrate 110 of the substrate 100), the fluoropolymer coating 230 may be adjacent to the moth-eye coatings 120a, 220. When the stacked removable lens layers 200 are laminated to the substrate 100, each fluoropolymer coating 230 may thus be shaped to conform to the moth-eye coatings 120a, 220 of the adjacent preceding layer 100, 200. The mechanical interlocking between the moth-eye coatings 120a, 220 and the corresponding molded concave patterns formed in the adjacent fluoropolymer coating 230 acts like a zipper, securing the adjacent layers together. Due to this mechanical interlocking, the use of acrylic or other sticky adhesives on the moth-eye coatings 120a, 220 is completely avoided, preventing the increase in peel strength associated with such conventional adhesives accumulating around the protrusions of the moth-eye coatings 120a, 220. Therefore, the removable lens layer 200 can advantageously have a much lower peel strength, which can be less than 100 grams per inch, for example, between 15 and 50 grams per inch, or more specifically, between 15 and 30 grams per inch (such as 25 grams per inch), allowing the wearer to remove each layer 200 as needed with a reasonable amount of pulling force. (It should be noted that since the base layer 100 does not need to be removable, there may not be a problem in attaching the base layer 100 to a surface with a sticky adhesive. Therefore, the increase in peel strength caused by the accumulation of adhesive around the protrusions of the optional moth-eye coating 120b is acceptable.)

[0043] The substrates 110 and 210 of each layer 100 and 200 may comprise a transparent polymer, such as polyethylene terephthalate (PET), and may have a thickness of 1 to 10 mils. For example, the substrate 210 of each removable lens layer 200 may be about 2 mils thick, and the substrate 110 of the base layer 100 may be of the same thickness or typically thicker (e.g., 7 mils). The moth-eye coating 220 of each removable lens layer 200 and the moth-eye coatings 120a and 120b of the base layer 100 may comprise a polymer, and may typically be made of a hard polymer, such as glassy carbon with a Mohs hardness of 7. The moth-eye coatings 120a, 120b, and 220 may define nanoscale microprotrusions or raised patterns (e.g., transparent cones) on the surface of the substrates 110 and 210 to produce an anti-reflective effect. The size of the nanoscale microprotrusions or raised patterns is on the order of light (e.g., visible light) wavelength, such as half-wave pitch and / or half-wave height. For example, the pitch and / or height of the protrusions can be 200-375 nm. The protrusions of the moth-eye coatings 120a, 120b, and 220 can have various shapes, including circular or rectangular protruding surfaces instead of cones.

[0044] The moth-eye coatings 120a, 120b, and 220 can be refractively matched (e.g., within 0.2) to the substrates 110 and 210, the fluoropolymer coating 230, and any usable adhesive (described below) so that the entire removable lens stack 10 can have a uniform refractive index (e.g., within 0.2). However, since the outermost moth-eye coating 220 effectively eliminates the refractive index interface between air and the removable lens stack 10 (because the interface changes gradually rather than abruptly in the material from the angle of incident light), it is not necessary to refractively match the removable lens stack 10 to air (n=1). Therefore, it is possible to use multiple materials for the substrates 110 and 210, as well as other components of the removable lens stack 10.

[0045] Generally, when constructing a conventional removable lens stack, a removable adhesive is used to co-wet each pair of adjacent surfaces. In this context, the term "wetting" can refer to the contact between two surfaces such that all air trapped between them is removed, resulting in good adhesion. However, simply placing one lens on top of another does not dissipate the air trapped between the lenses; therefore, an acrylic removable adhesive can be used to co-wet the surfaces and promote adhesion. By matching the adhesive's refractive index to the lens's refractive index (e.g., within 0.2), visible light can maintain a constant velocity at the interface, minimizing reflection. An example of such a system can be found in U.S. Patent No. 9,295,297 entitled "Adhesive Mountable Stack of Removable Layers," the entire contents of which are expressly incorporated herein by reference. However, because the adhesive has a sticky feel, problems arise when bonding two surfaces (one or both of which have a moth-eye coating) together. Specifically, as described above, the adhesive fills around the micro-protrusions of the moth-eye coating, significantly improving peel strength beyond the appropriate range for removable lens stacking functionality.

[0046] Therefore, in order to wet the surfaces of the substrates 110, 210 together and achieve the preferred peel strength of the removable lens stack 10 of this disclosure, a fluoropolymer coating 230 may be provided on the second side 214 of each substrate 210. The fluoropolymer coating 230 may be a soft fluoropolymer with a refractive index matching (e.g., within 0.2), such as fluorinated ethylene-propylene copolymer (FEP), perfluoroalkoxyalkane (PFA), or tetrafluoroethylene perfluoro(methyl vinyl ether) (MFA), which is non-sticky to the touch but can be molded under lamination pressure to produce recessed (concave) patterns corresponding to the protrusions of adjacent moth-eye coatings 120a, 220.

[0047] In some cases, adhesion treatments 140a, 240 may be provided between the substrate 110 of the base layer 100 and the moth-eye coating 120a and / or between the substrate 210 of each removable lens layer 200 and the moth-eye coating 220. Similarly, if the substrate 110 of the base layer 100 also includes a moth-eye coating 120b on its second side 114, an adhesion treatment 140b may be provided between the substrate 110 and the moth-eye coating 120b. In each removable lens layer 200, an adhesion treatment 250 may similarly be provided between the substrate 210 and the fluoropolymer coating 230. Adhesion treatments 140a, 140b, 240, 250 may comprise pressure-sensitive adhesives, such as silicone adhesives (e.g., polydimethyl / methylvinylsiloxane polymers and resins dispersed in toluene / isopropanol, such as adhesives sold by Dow Chemical Company under the names DOWSIL™ 7655 adhesive or DOWSIL™ 7656 adhesive). The adhesive can be refractively matched (e.g., within 0.2) with the aforementioned substrates 110, 210 and other elements of the removable lens stack 10.

[0048] A base layer 100 and one or more removable lens layers 200 can be manufactured by coating each substrate 110, 210 with a moth-eye coating 120a, 120b, 220 and a fluoropolymer coating 230. In some cases, the moth-eye coating and the fluoropolymer coating can be adhered to the substrates 110, 210 by adhesion processes 140a, 140b, 240, 250 as described above. To improve adhesion, it is also considered that corona treatment can be applied between the substrates 110, 210 and the moth-eye coatings 120a, 120b, 220 and / or between the substrate 210 and the fluoropolymer coating 220. For example, this can ensure that the fluoropolymer coating 220 and the outermost removable lens layer 200 detach together from the removable lens stack 10. Corona treatment can be applied instead of the aforementioned adhesion treatments 140a, 140b, 240, and 250, or corona treatment can be applied in addition to the aforementioned adhesion treatments 140a, 140b, 240, and 250. The removable lens layers 200 can then be stacked on top of the substrate layer 100, such that the second side 214 of the substrate 210 of each removable lens layer 200 faces the substrate layer 100 and the first side 112, 212 of the immediately preceding substrate 110, 210 of one or more removable lens layers 200 (depending on the specific situation). Figure 1 , 2 In the examples, a first removable lens layer 200 (as shown in the middle of each figure) is stacked on top of a base layer 100, and a second removable lens layer 200 (as shown on the left side of each figure) is stacked on top of the first removable lens layer 200. Additional removable lens layers 200 can also be provided and added in the stack similarly.

[0049] The removable lens layer 200 can then be laminated to the substrate layer 100 under pressure and with or without heating, for example, under pressure and at a temperature below 40°C. It should be noted that the substrate layer 100 and the removable lens layer 200 can be laminated together by a single lamination process or by multiple lamination processes, for example, each removable lens layer 200 is added to the stack by separate lamination processes (or multiple removable lens layers 200 are first laminated together and then laminated to the substrate layer 100). As a result of lamination, each fluoropolymer coating 230 can be shaped to conform to the moth-eye coating 120a, 220 immediately preceding it. In particular, the hard protrusions of the moth-eye coatings 120a, 220 can be pressed into the soft fluoropolymer coating 230, thereby forming corresponding recessed (concave) patterns in the fluoropolymer coating 230. In this way, the mechanical interlocking between layers 100 and 200 can be achieved, resulting in the required peel strength (e.g., 25 grams per inch) without the use of a sticky adhesive between layers 100 and 200 that would fill the gaps between the protrusions and excessively increase the peel strength. Simultaneously, air between layers 100 and 200 can be expelled during lamination, which wets the opposing layers 100 and 200 (thus creating slight adhesion), while the refractive index interface can be effectively eliminated due to the refractive index gradient formed by the moth-eye coatings 120a and 220. The resulting removable lens stack 10 has a visible light transmittance (VLT) greater than 95% (e.g., 96%, reflectance 4%), compared to 92% VLT and 8% reflectance in an uncoated lens. In some cases, particularly when the moth-eye coating 120b is provided such that both sides of the stack 10 have moth-eye coatings 120a, 120b, and 220, the VLT can be greater than 98% (e.g., >99%).

[0050] When the removable lens stack 10 is incorporated into and worn in eyeglasses, the wearer can easily peel off the outermost removable lens layer 200 to expose the intact underlying removable lens layer 200 (or base layer 100). In cases where the removable lens stack 10 has multiple removable lens layers 200, the pulling force used to remove the outermost removable lens layer 200 typically involves an initial outward force (perpendicular to the stack 10) at which point the wearer peels the outermost removable lens layer 200 from one side of the stack 10, separating it from another removable lens layer 200 (e.g., by grasping a pull tab on one side of the stack 10), followed by the application of a continuous lateral force (with a component parallel to the stack 10), at which point the wearer peels off the outermost removable lens layer 200. It is conceivable that this continuous lateral force, primarily responsible for separating the removable lens layers 200, might be more inclined to peel off the outermost removable lens layer 200 than to separate subsequent layers 200 below. Therefore, the wearer can easily peel off one layer 200 at a time without accidentally tearing off the additional layer 200 of the removable lens stack 10.

[0051] Hybrid stacking is also conceivable, where one or more layers with moth-eye coatings can be combined with one or more layers with alternative types of antireflective coatings, such as single-layer or multi-layer interference antireflective coatings. For example, Figure 3 Is with Figure 1 Cross-sectional view of the same substrate 100, but Figure 3 It contains one removable lens layer 300 and two removable lens layers 400, which can be stacked together to form a shape such as Figure 4 The removable lens stack 20 is shown in cross-section. The base layer 100 of the removable lens stack 20 can be coupled with... Figure 1 and Figure 2The base layer 100 of the removable lens stack 10 shown is identical and can be similarly fixed to a surface such as a goggle lens or face shield, or a transparent window on a surgical helmet, hood, or gown, or its periphery can be attached to a frame, so that the removable lens stack 20 itself functions as a lens, face shield, mask, etc. Advantageously, the removable lens stack 20 employs a moth-eye coating in some, but not all, layers, thereby reducing the difficulties and costs associated with producing the moth-eye coating. In the illustrated embodiment, for example, the base layer 100 is the only layer with a moth-eye coating, while the removable lens layers 300, 400 have single-layer or multi-layer interference antireflective coatings 340, 440 that may be cheaper to produce (e.g., by spin coating, dip coating, or vacuum deposition). Specifically, the first removable lens layer 300 may include a substrate 310, a single or multiple interference antireflective coating 340 on a first side 312 of the substrate 310, and a fluoropolymer coating 330 (with optional adhesion treatment 350) on a second side 314 of the substrate 310 opposite to the first side 312. As described above, when the first removable lens layer 300 is stacked on top of the base layer 100 and the second side 314 of the substrate 310 faces the first side 112 of the substrate 110 of the base layer 100, the fluoropolymer coating 330 can be shaped to conform to the moth-eye coating 120a.

[0052] One or more removable lens layers 400 may also be added to the stack, each removable lens layer 400 comprising a substrate 410, a single or multiple interference antireflective coating 440 on a first side 412, and an adhesive 450 (such as an acrylic or polyurethane adhesive) on a second side 414. One such removable lens layer 400 may be stacked on top of a removable lens layer 300 such that the second side 414 of the substrate 410 faces the first side 312 of the substrate 300. More removable lens layers 400 may be stacked on top thereon, with the second side 414 of each substrate 410 facing the first side 412 of each preceding substrate 400. By using antireflective coatings 340, 440 that do not have protrusions like the moth-eye coating 120a, any concerns about the adhesive 450 filling around the protrusions and undesirably increasing peel strength can be avoided. Therefore, various adhesives 450, including acrylic or polyurethane adhesives, such as pressure-sensitive adhesives (PSA), can be used, which can adhere (e.g., by applying pressure) to the preceding antireflective coatings 340, 440. The hybrid removable lens stack 20 effectively achieves the superior antireflective properties of the moth eye by incorporating it into one or more layers, while benefiting from one or more inexpensive layers of antireflective coatings 340, 440 and / or adhesives 450. Thus, the hybrid removable lens stack 20 represents a "win-win" compromise that balances high antireflective requirements with manufacturing costs.

[0053] exist Figure 3 and Figure 4 In the example, a removable lens layer 300 (having a non-mear antireflective coating 340 and a fluoropolymer coating 330 bonded to a moth-eye coating 120a of the substrate layer 100) and two removable lens layers 400 (having a non-mear antireflective coating 440 and an acrylic or polyurethane adhesive 450) are shown, stacked on the substrate layer 100 to form a removable lens stack 20. However, mixed stacks of various other combinations of layers are also contemplated. For example, more or fewer removable lens layers 400 may be used. Furthermore, one or more removable lens layers 200 may be added between the substrate layer 100 and the removable lens layer 300 (see [link to example]). Figure 1 and Figure 2 In this case, the fluoropolymer coating 330 of the removable lens layer 300 can be bonded to the moth-eye coating 220 of the outermost removable lens layer 200, rather than directly to the moth-eye coating 120a of the substrate layer 100. Alternatively, the substrate with the moth-eye coating can be bonded to the outermost part of the stack, below which are one or more substrates with non-moth-eye anti-reflective coatings. For this purpose, a modified layer 400 with a moth-eye coating replacing the non-moth-eye anti-reflective coating 440 can be used (but still bonded to the underlying non-moth-eye anti-reflective coating using acrylic or polyurethane adhesive 450). Hybrid removable lens stacks 20 with various structures can be economically designed and manufactured according to the specific needs of manufacturers and consumers, taking into account both the required level of anti-reflection and the desired unit cost.

[0054] It should also be noted that the use of moth-eye coatings (i.e., forward and backward moth-eye patterns) on both sides of a single layer is not necessarily limited to the base layer 100. Such bilateral moth-eye layers can be included at any point in the removable lens stack 10 or 20. For example, the stack may consist of multiple layers 100 stacked on top of each other (in some cases, this may be the only layer type in the stack, such as a stack consisting of three layers 100). A fluoropolymer coating shaped as a moth-eye coating as described above can be applied between each pair of adjacent layers 100, except that in this case, the fluoropolymer coating can be shaped as two opposing moth-eye coatings with the fluoropolymer coating located between them. As an example method of stacking multiple such bilateral moth-eye layers 100, a fluoropolymer coating can be applied to the forward moth-eye coating 120a of the first layer 100, shaping one side of the fluoropolymer coating into the shape of the forward moth-eye coating 120a. Subsequently, a second layer 100 can be stacked on top of the fluoropolymer coating and laminated, shaping the other side of the fluoropolymer coating into the shape of the backward moth-eye coating 120b of the second layer 100. More layers 100 (or combined with other types of layers described above) can be stacked in the same manner, wherein the fluoropolymer coating is shaped into the shape of two adjacent moth-eye coatings if necessary. Preferably, a release treatment can be applied to each forward moth-eye coating 120a, and / or an adhesion-promoting treatment can be applied to each backward moth-eye coating 120b, thereby causing the fluoropolymer coating to detach with each layer 100 when it is removed from the stack. By using bilateral moth-eye layers in this manner, a high degree of anti-reflection can be achieved. Furthermore, depending on the moth-eye manufacturing process used, producing two moth-eye coatings 120a and 120b on the same substrate 110 may be more cost-effective than producing a single moth-eye coating on separate substrates, making the use of double-sided moth-eye layers potentially more efficient. The manufacturing process can also be simplified (and cost-reduced) by using the same repeating layer 100 instead of multiple different layers.

[0055] Given that extremely low reflectivity can be achieved using a substrate layer 100 with a forward moth-eye coating 120a and / or a backward moth-eye coating 120b, it is anticipated that stacks with acceptable levels of antireflection can be obtained without the need for moth-eye layers or single or multiple interference antireflective coatings on removable layers. In particular, it has been found that acrylic coatings (such as acrylic coatings applied to a hard coating on a PET substrate) can increase the smoothness of the substrate's outer surface (which can be roughened during manufacturing for easier handling), thereby reducing haze. Furthermore, the lower refractive index of the acrylic coating compared to the PET substrate reduces reflection, making the stack more antireflective. Similarly, it has been found that fluoropolymer coatings (such as silicone or Teflon), such as fluoropolymer coatings applied to a hard coating on a PET substrate, can also increase the smoothness of the outer surface and reduce haze. Likewise, the difference in refractive index makes the stack more antireflective. By combining the moth-eye coatings 120a and 120b on the base layer 100, this stacking of acrylic or fluoropolymer coatings on the removable layer can achieve a balance between quality and cost-effectiveness. Furthermore, the acrylic or fluoropolymer coating can advantageously include an acrylic or fluoropolymer hard coating, for example, the acrylic or fluoropolymer hard coating can contain silica beads. In this way, in addition to providing anti-reflective effects, the intended coating can also provide the functions of a hard coating (such as increased scratch resistance).

[0056] refer to Figure 5 It shows the same as Figure 1 Cross-sectional view of the same substrate 100, but Figure 5 It has a removable lens layer 500 and a removable lens layer 600, which can be stacked together to form a shape such as Figure 6 The removable lens stack 30 is shown in cross-section. The base layer 100 of the removable lens stack 30 can be coupled with... Figure 1 and Figure 2The base layer 100 of the removable lens stack 10 shown is identical and can be similarly fixed to a surface such as a goggle lens or face shield, or a transparent window on a surgical helmet, hood, or gown, or its periphery can be attached to a frame, so that the removable lens stack 30 itself functions as a lens, face shield, mask, etc. Advantageously, similar to the removable lens stack 20, the removable lens stack 30 can employ a moth-eye coating in some but not all layers, thereby reducing the difficulties and costs associated with producing the moth-eye coating. For example, in the illustrated embodiment, the base layer 100 is the only layer with a moth-eye coating, while the removable lens layers 500, 600 have an acrylic or fluoropolymer coating 540, 640 (e.g., a hard coating) that may be cheaper to produce (e.g., by spin coating, dip coating, or vacuum deposition) than the moth-eye coating. Specifically, the first removable lens layer 500 may include a substrate 510, an acrylic or fluoropolymer coating 540 (e.g., a hard coating) on ​​a first side 512 of the substrate 510, and a fluoropolymer coating 530 (with optional adhesion treatment 550) on a second side 514 of the substrate 510 opposite to the first side 512. As described above, when the first removable lens layer 500 is stacked on top of the base layer 100 and the second side 514 of the substrate 510 faces the first side 112 of the substrate 110 of the base layer 100, the fluoropolymer coating 530 can be shaped to conform to the moth-eye coating 120a.

[0057] One or more removable lens layers 600 may also be added to the stack, each removable lens layer 600 comprising a substrate 610, an acrylic or fluoropolymer coating 640 (e.g., a hard coating) on ​​a first side 612, and an adhesive 650 (e.g., an acrylic or polyurethane adhesive) on a second side 614. One such removable lens layer 600 may be stacked on top of a removable lens layer 500 such that the second side 614 of the substrate 610 faces the first side 512 of the substrate 500. Although not specifically shown, more removable lens layers 600 may be stacked on top, with the second side 614 of each substrate 610 facing the first side 612 of each preceding substrate 600. By using an acrylic or fluoropolymer coating 540, 640 that does not have protrusions like the moth-eye coating 120a instead of a conventional antireflective coating, any concerns about the adhesive 650 filling around the protrusions and undesirably increasing peel strength can be avoided. Therefore, a variety of adhesives 650, including acrylic or polyurethane adhesives, such as pressure-sensitive adhesives (PSA), can be used, which can adhere (e.g., by applying pressure) to the preceding acrylic or fluoropolymer coatings 540, 640 (e.g., hard coatings). The hybrid removable lens stack 30 can effectively achieve the superior anti-reflective properties of the moth eye by bonding it to one or more layers, while benefiting from one or more inexpensive layers of coatings 540, 640 and / or adhesives 550, where in some cases, coatings 540, 640 serve the dual purpose of providing sufficient anti-reflective properties and the functionality of a hard coating.

[0058] The above description is given by way of example and not limitation. Based on the above disclosure, those skilled in the art can devise various variations within the scope and spirit of the invention disclosed herein. Furthermore, the various features of the disclosed embodiments can be used individually or in different combinations thereof, and are not intended to be limited to the specific combinations described herein. Therefore, the scope of the claims is not limited to the embodiments shown.

Claims

1. A removable lens stack, comprising: The base layer includes a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. A first removable lens layer includes a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked on top of the base layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the base layer; as well as The second removable lens layer includes a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the second removable lens layer being stacked on top of the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

2. The removable lens stack of claim 1, wherein the acrylic coating of each of the first removable lens layer and the second removable lens layer comprises a hard acrylic coating.

3. The removable lens stack of claim 2, wherein the acrylic hard coating comprises silica beads.

4. The removable lens stack of claim 1, wherein the first removable lens layer further comprises a fluoropolymer coating on a second side of the substrate, the fluoropolymer coating being shaped to conform to the moth-eye coating on a first side of the substrate of the base layer.

5. The removable lens stack of claim 1, wherein the second removable lens layer further comprises an acrylic adhesive located on a second side of the substrate.

6. The removable lens stack of claim 1, wherein the second removable lens layer further comprises a polyurethane adhesive located on a second side of the substrate.

7. A removable lens stack, comprising: The base layer includes a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. as well as A first removable lens layer includes a substrate and an acrylic coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked on top of the base layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the base layer.

8. The removable lens stack of claim 7, wherein the acrylic coating comprises a hard acrylic coating.

9. The removable lens stack of claim 8, wherein the acrylic hard coating comprises silica beads.

10. The removable lens stack of claim 7, wherein the first removable lens layer further comprises a fluoropolymer coating on a second side of the substrate, the fluoropolymer coating being shaped to conform to the moth-eye coating on a first side of the substrate of the base layer.

11. The removable lens stack of claim 7, further comprising a second removable lens layer, the second removable lens layer comprising a substrate, an acrylic coating on a first side of the substrate, and an acrylic adhesive on a second side of the substrate opposite to the first side, the second removable lens layer being stacked on top of the first removable lens layer such that a second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

12. The removable lens stack of claim 7, further comprising a second removable lens layer, the second removable lens layer comprising a substrate, an acrylic coating on a first side of the substrate, and a polyurethane adhesive on a second side of the substrate opposite to the first side, the second removable lens layer being stacked on top of the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

13. A removable lens stack, comprising: The base layer includes a substrate, a moth-eye coating on a first side of the substrate, and a moth-eye coating on a second side of the substrate opposite to the first side. as well as A first removable lens layer includes a substrate and a fluoropolymer coating on a first side of the substrate, the substrate having a second side opposite to the first side, the first removable lens layer being stacked on top of the base layer such that the second side of the substrate of the first removable lens layer faces the first side of the substrate of the base layer.

14. The removable lens stack of claim 13, wherein the fluoropolymer coating of the first removable lens layer comprises a fluoropolymer hard coating.

15. The removable lens stack of claim 14, wherein the fluoropolymer hard coating comprises silica beads.

16. The removable lens stack of claim 13, wherein the first removable lens layer further comprises a fluoropolymer coating on a second side of a substrate, the fluoropolymer coating on the second side of the substrate of the first removable lens layer being shaped to conform to the moth-eye coating on a first side of the substrate of the base layer.

17. The removable lens stack of claim 13, further comprising a second removable lens layer comprising a substrate and a fluoropolymer coating on a first side of the substrate, the substrate having a second side opposite to the first side, the second removable lens layer being stacked over the first removable lens layer such that the second side of the substrate of the second removable lens layer faces the first side of the substrate of the first removable lens layer.

18. The removable lens stack of claim 17, wherein the second removable lens layer further comprises an acrylic adhesive located on a second side of the substrate.

19. The removable lens stack of claim 17, wherein the second removable lens layer further comprises a polyurethane adhesive located on a second side of the substrate.

20. The removable lens stack of claim 17, wherein the fluoropolymer coating of the second removable lens layer comprises a fluoropolymer hard coating.

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