Light control film

Abstract

A light control film includes an optical film shaped to define a plurality of substantially linearly alternating ridges and grooves extending in a substantially identical first direction and arranged in an orthogonal second direction. Each of the trenches includes a first layer and a second layer disposed therein and stacked in a thickness direction of the light control film. The second layer is disposed between the first layer and the bottom of the trench. For each adjacent pair of ridges and trenches of the plurality of alternating ridges and trenches, an interface layer extending substantially coextensive with the ridge in the first direction is disposed between the ridge and the first layer disposed in the trench such that at least a portion of the second layer is not separated from the ridge by the interface layer.

Description

TECHNICAL FIELD

[0001] This specification generally relates to light control films. BACKGROUND

[0002] Light control films generally control the angular distribution of light transmitted through the light control film. SUMMARY

[0003] In some aspects, this specification provides a light control film comprising an optical film shaped to define a plurality of substantially linear alternating ridges and grooves extending along a first substantially same direction and arranged along a second orthogonal direction. Each of the grooves comprises a first layer and a second layer disposed therein and stacked along a thickness direction of the light control film. Each of the first layer and the second layer has a maximum thickness greater than about 0.01 micrometers. The second layer is disposed between the first layer and a bottom of the groove. For each pair of adjacent ridges and grooves of the plurality of alternating ridges and grooves, an interface layer substantially coextensive with the ridge along the first direction is disposed between the ridge and the first layer disposed in the groove such that at least a portion of the second layer is not separated from the ridge by the interface layer. The interface layer has a maximum thickness greater than about 0.01 micrometers and less than about 10 micrometers.

[0004] In some aspects, this specification provides a light control film having a structured major surface that extends continuously substantially across an entire length and an entire width of the light control film and comprises a plurality of structures. Each of the structures has a top surface extending between and joining opposite side surfaces. The light control film is such that for each pair of adjacent first and second structures of the plurality of structures: a first side surface of the first structure faces a second side surface of the second structure, wherein the first side surface and the second side surface are interconnected by a connecting surface portion of the structured major surface; a first layer having a same first composition coats at least a majority of each of the first side surface and the second side surface; and a same second layer having a same second composition different from the first composition coats at least a majority of the connecting surface portion and coats adjacent portions of the first side surface and the second side surface.

[0005] In some aspects, the present specification provides a light control film having a structured major surface that extends continuously across an entire length and an entire width of the light control film and includes a plurality of structures. Each structure of the structures has a top surface extending between and joining opposite side surfaces of the structure. The light control film is such that for each structure of the plurality of structures: a first layer having a same first composition is disposed on and coextensive with at least a majority of each of the first and second side surfaces; and a second layer having a same second composition different from the first composition coats at least a majority of the top surface and a portion of each of the first and second side surfaces adjacent to the top surface.

[0006] In some aspects, the present specification provides a method of manufacturing a light control film. The method includes: depositing an optically absorbing layer onto a first structured major surface of a first film such that the optically absorbing layer substantially conforms to the first structured major surface, wherein the first structured major surface includes a plurality of first structures arranged along a first direction and defining a plurality of first channels extending along an orthogonal second direction, and wherein each first channel is disposed between adjacent first structures and has an open top opposite a bottom of the first channel; removing the optically absorbing layer from a top portion of each first structure of the plurality of first structures, wherein the top portion of the first structure is adjacent to the open top of the first channel; for each first channel of the plurality of first channels, disposing a release layer on the optically absorbing layer along the bottom of the first channel and along at least a portion of a sidewall of the first structure adjacent to the first channel; after the removing and disposing steps, substantially filling each first channel of the plurality of first channels with a resin; solidifying the resin to form a second film including a land portion and a second structured major surface including a plurality of second structures, wherein each second structure extends from the land portion to a top portion of the second structure, and wherein the top portion extends between and joins opposite sidewalls of the second structure; separating the first film and the second film such that the second film includes the optically absorbing layer disposed on the sidewalls and the top portion of the second structure; and for each second structure of the plurality of second structures, removing the optically absorbing layer from at least the top portion of the second structure to expose the release layer.

[0007] In some aspects, the present specification provides a method of manufacturing a light control film. The method includes, for a first film comprising a first structured major surface comprising a plurality of first structures arranged along a first direction and defining a plurality of first channels extending along an orthogonal second direction, wherein each first channel is disposed between adjacent first structures and has an open top opposite a bottom of the first channel, and wherein each of the first structures has a top surface extending between and joining opposite side surfaces of the first structure, coating a release layer onto the top surface of the first structures; substantially filling each of the plurality of first channels with a resin; solidifying the resin to form a second film comprising a platform portion and a second structured major surface comprising a plurality of second structures, wherein each second structure extends from the platform portion to a top surface of the second structure, and wherein the top surface extends between and joins opposite side walls of the second structure; separating the first film and the second film such that the second film comprises the release layer disposed on the platform portion; depositing an optically absorbing layer onto the second structured major surface such that the optically absorbing layer substantially conforms to the second structured major surface; and removing the optically absorbing layer from the top surface of the second structure and from the release layer.

[0008] These and other aspects will become apparent from the following detailed description. To the extent that any meaning or definition of a term in this document conflicts with the meaning or definition of the same term in a patent, application, or other document incorporated herein by reference, the meaning or definition that is consistent with this document shall prevail. To the extent that any meaning or definition of a term in this document conflicts with the meaning or definition of the same term used in any document incorporated herein by reference, the meaning or definition that is consistent with this document shall prevail. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figures 1-2 is a schematic cross-sectional view of a light control film in accordance with some embodiments.

[0010] Figure 3 is a schematic cross-sectional view of an optical film 10 in accordance with some embodiments.

[0011] Figures 4-5 is a schematic cross-sectional view of a portion of an optical film in accordance with some embodiments.

[0012] Figures 6-7 is a schematic cross-sectional view of a light control film in accordance with some embodiments, in which a second layer covers portions of the sidewalls of the ridges.

[0013] Figures 8-9 is a schematic cross-sectional view of a light control film in accordance with some embodiments, in which a second layer covers portions of the top of the ridges and the sidewalls.

[0014] Figure 10 is a schematic cross-sectional view of a light control film disposed adjacent to a light source in accordance with some embodiments.

[0015] Figure 11 An initial step of a process for manufacturing a light control film according to some embodiments is schematically illustrated.

[0016] Figures 12-13 A step of a process for manufacturing a light control film according to some embodiments is schematically illustrated.

[0017] Figure 14 A process for manufacturing a light control film according to some embodiments is schematically illustrated.

[0018] Figures 15-16 A scanning electron microscope (SEM) image of an exemplary light control film according to some embodiments. DETAILED DESCRIPTION

[0019] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration various embodiments. The drawings are not necessarily to scale. It is to be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0020] Light control films can include alternating light absorbing regions and light transmitting regions to control the angular distribution of light transmitted through the light control film. The light absorbing regions can have a large aspect ratio (height divided by thickness) in order to provide high on-axis transmission, as described in U.S. Patent Application Nos. 2021 / 0333624 (Schmidt et al.); 2022 / 0019007 (Schmidt et al.); and 2023 / 00289558 (Liu et al.), for example, where the light absorbing regions are formed via layer-by-layer (LbL) self-assembly, followed by reactive ion etching to remove the LbL material from the horizontal surfaces where transmission is desired.

[0021] According to some embodiments of the present specification, methods of forming light control films are provided that utilize light absorbing regions that can be formed via LbL self-assembly, for example, without the need for, for example, a reactive ion etching step or other vacuum processing steps. The described methods can be, for example, more cost effective than traditional methods. According to some embodiments, the resulting light control films can include a release layer that can be embedded in the light control film.

[0022] Figures 1-2is a schematic cross-sectional view of a light control film according to some embodiments. In some embodiments, light control film 300, light control film 400 (or other light control films described elsewhere herein) include optical film 10 shaped to define a plurality of substantially linear alternating ridges 20 and troughs 30 extending along a substantially same first direction (y-direction) and arranged along an orthogonal second direction (x-direction), wherein each of the troughs 30 includes a first layer 31 disposed therein. Alternatively or additionally, in some embodiments, light control film 300, light control film 400 can be described as including optical film 10' shaped to define a plurality of substantially linear alternating ridges 20' and troughs 30' extending along a substantially same first direction (y-direction) and arranged along an orthogonal second direction (x-direction), wherein each of the troughs includes a first layer 31' disposed therein. In some embodiments, each of the troughs 30 of optical film 10 includes a second layer 32 disposed therein (e.g., at least on a bottom 33 of the trough and / or between the bottom 33 and the first layer 31), wherein the first and second layers can be stacked along a thickness direction (z-direction) of the light control film, and the second layer can be disposed between the first layer and the bottom 33 of the trough. Alternatively or additionally, in some embodiments, light control film 300, light control film 400 can be described as including a second layer 32 disposed on at least a top 21 of each of the ridges 20' of optical film 10'. In some embodiments, as Figure 2 schematically shown in FIG. 1C, each of the troughs 30' of optical film 10' includes a second layer 32' disposed therein (e.g., at least on a bottom 33' of the trough and / or between the bottom 33' and the first layer 31'), wherein the first and second layers can be stacked along a thickness direction (z-direction) of the light control film, and the second layer can be disposed between the first layer and the bottom 33' of the trough. Alternatively or additionally, in some embodiments, light control film 400 can be described as including a second layer 32' disposed on at least a top 21 of each of the ridges 20 of optical film 10.

[0023] In some embodiments, the second layer 32 and / or the second layer 32' can also be disposed on portions of the opposite sides of the ridges of optical film 10 and / or optical film 10', as further described elsewhere herein.

[0024] For example, the plurality of substantially linear alternating ridges 20 and troughs 30 extending along a substantially same first direction can extend nominally linearly along the first direction, or can extend linearly along the first direction until a deviation along the second direction is less than about 20%, 10%, or 5% of an average spacing of the ridges along the second direction.

[0025] In some embodiments, the optical film 10 is shaped to further define a platform portion 11 that extends substantially continuously across the length (y-direction) and width (x-direction) of the optical film 10 and joins the ridges 20 and the channels 30. In some embodiments, the first layer 31 is joined by a platform portion 11’ that has the same composition as the first layer, extends substantially continuously across the length (y-direction) and width (x-direction) of the optical film, and covers the top of the ridges. In some embodiments, the optical film 10’ is shaped to further define a platform portion 11’ that extends substantially continuously across the length (y-direction) and width (x-direction) of the optical film 10’ and joins the ridges 20’ and the channels 30’. In some embodiments, the platform portion 11 and / or the platform portion 11’ extends across greater than 60%, 70%, 80%, 90%, or 95% of each of the length and width of the optical film. In some embodiments, the platform portion 11 and / or the platform portion 11’ can be omitted. In some embodiments, the channel 30 (or 30’) has a bottom portion 35 (or 35’) that includes the bottom 33 (or 33’) of the channel. The bottom portion 35, the bottom portion 35’ can be or include a connecting surface portion that extends between and connects the side surfaces of adjacent ridges. In some embodiments, the platform portion 11 and / or the platform portion 11’ has an average thickness greater than about 0.2 microns, 0.5 microns, 1 micron, 2 microns, 5 microns, or 10 microns (see, e.g., t3 depicted in FIG. 3). In some embodiments, the average thickness of the platform portion is less than about 50 microns, 45 microns, 40 microns, 35 microns, 30 microns, 25 microns, or 20 microns. Figure 3 In some embodiments, the platform portion 11 and / or the platform portion 11’ has an average thickness greater than about 0.2 microns, 0.5 microns, 1 micron, 2 microns, 5 microns, or 10 microns (see, e.g., t3 depicted in FIG. 3). In some embodiments, the average thickness of the platform portion is less than about 50 microns, 45 microns, 40 microns, 35 microns, 30 microns, 25 microns, or 20 microns.

[0026] In some embodiments, optical film 10 is disposed on a substrate 60. In some embodiments, optical film 10 is disposed on a substrate 60’. In some embodiments, at least one of substrate 60, substrate 60’ is omitted. In some embodiments, at least one of substrate 60, substrate 60’ is or includes a glass layer. In some embodiments, at least one of substrate 60, substrate 60’ is or includes a polymeric film. Polymers that can be used for polymeric films (e.g., for extrusion replication or replication by photopolymerization) include, for example, styrene-acrylonitrile, cellulose acetate butyrate, cellulose acetate propionate, cellulose triacetate, polyether sulfone, polymethyl methacrylate, polyurethane, polyester, polycarbonate, polyvinyl chloride, polystyrene, polyethylene naphthalate, copolymers or blends based on naphthalene dicarboxylic acid, polyolefin-based materials such as cast or oriented films of polyethylene, polypropylene, and polycycloolefins, polyimide, or combinations of these materials. For example, the polymeric film can be a polyethylene terephthalate (PET) film, a polypropylene film, or a polycarbonate film. The film can be oriented (e.g., uniaxially or biaxially). In some embodiments, the polymeric film is a multilayer optical film. Useful multilayer optical films include those described in, for example, U.S. Patent Nos. 5,882,774 (Jonza et al.); 6,783,349 (Neavin et al.); 6,949,212 (Merrill et al.); 6,967,778 (Wheatley et al.); 9,162,406 (Neavin et al.); and 11,493,677 (Haag et al.). Multilayer optical films can be included to provide a better defined effective viewing angle cutoff, for example, as described in U.S. Patent No. 8,503,122 (Liu et al.).

[0027] In some embodiments, optical film 10 has a structured major surface 15. In some embodiments, optical film 10' has a structured major surface 15'. In some embodiments, one of optical film 10, optical film 10' is formed on a substrate 60, 60' using a casting and solidifying (e.g., curing) process, and the other of optical film 10, optical film 10' is formed by backfilling the resulting trenches with a resin (e.g., a polymerizable material or a molten polymer) and solidifying (e.g., via curing or cooling) the resin to provide a film. The casting and solidifying process can result in a land 11 or land 11', and backfilling and solidifying can also optionally result in a land 11' or land 11. The casting and solidifying process can be a cast and cure process that uses a polymerizable resin composition that is brought into contact with a structured surface of a tool by casting and curing (e.g., by applying actinic radiation such as ultraviolet (UV) radiation) to microreplicate the structure of the tool. Such casting and curing methods are described in, for example, U.S. Patent Nos. 5,175,030 (Lu et al.) and 5,183,597 (Lu), and in U.S. Patent Application Publication No. 2012 / 0064296 (Walker, JR. et al.). Further details regarding useful processes for making light control films are described elsewhere herein. In some embodiments, optical film 10' is omitted. In some embodiments, first layer 31 is air or mostly air. In other embodiments, optical film 10' is a polymer film, and optical film 10 is omitted. In some embodiments, first layer 31' is air or mostly air. For example, the backfilling and curing steps can optionally be omitted.

[0028] In some embodiments, a layer 40 is disposed between each pair of adjacent ridges 20 and ridges 20'. Layer 40 can be an optically absorbing layer. In Figures 1-2 The thickness t of layer 40 is schematically illustrated in FIGS. 1 1 and 12. Thickness t can schematically represent the maximum thickness of layer 40 or the average thickness of a plurality of layers 40. Layer 40 has an average height hi in a thickness direction of light control film 300, light control film 400, which is orthogonal to each of the first and second directions. In some embodiments, layer 40 has an average thickness t along the thickness direction (z-direction) and an average height hi, where hi / t 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, or 200. For example, the aspect ratio hltmay be as high as 10,000 or 5,000 or 1,000. In some embodiments, the (interface) layer 40 has a maximum thickness greater than about 0.01 microns, 0.025 microns, 0.05 microns, 0.1 microns, 0.15 microns, 0.2 microns, 0.25 microns, 0.3 microns, 0.35 microns, 0.4 microns, 0.45 microns, 0.5 microns, 0.55 microns, or 0.6 microns. In some embodiments, the maximum thickness is less than about 10 microns, 9 microns, 8 microns, 7 microns, 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1.5 microns. Such high aspect ratio layers can be formed via LbL self-assembly, for example, as further described elsewhere herein.

[0029] In some embodiments, the ridge 20 has an average height h2in the thickness direction. In some embodiments, the ridge 20' has an average height h2'in the thickness direction. In some embodiments, the difference between h2and h2'is the thickness of the layer 32. In some embodiments, h1is greater than about 0.5, 0.6, 0.7, 0.8, or 0.9 times h2. In some embodiments, h1is greater than about 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times h2'. In some embodiments, h2and h2'are each less than about 1 mm. In some embodiments, h1is greater than about 1 micron and less than each of h2and h2'.

[0030] The layer 40 can be an interface layer between the ridges and the first layer. In some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, the interface layer 40 that extends substantially coextensively with the ridges along the first direction is disposed between the ridges and the first layer disposed in the troughs such that at least a portion of the second layer is not separated from the ridges by the interface layer. In some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, the second layer directly contacts the ridges adjacent the bottom of the troughs. In some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, at least 50 area %, 60 area %, 70 area %, 80 area %, 90 area %, 95 area %, 96 area %, 97 area %, 98 area %, or 99 area % of the interface layer 40 is not disposed between the ridges and the second layer. Area here refers to the area of the major surface of the layer 40. In some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, no portion of the interface layer 40 is disposed between the ridges and the second layer. In some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, at least 60 area %, 70 area %, 80 area %, 90 area %, 95 area %, 96 area %, 97 area %, 98 area %, or 99 area % of the interface layer is disposed directly on the ridges.

[0031] An element (e.g., the interface layer 40) can be described as extending substantially coextensively along a direction with another element (e.g., the ridges) if at least about 60% of the length of each element along the direction is coextensive with at least about 60% of the length of each other element along the direction. In some embodiments, when one element extends substantially coextensively along a direction with another element, at least about 70%, 80%, or 90% of the length of each element along the direction is coextensive with at least about 70%, 80%, or 90% of the length of each other element along the direction. For example, in some embodiments, for each pair of adjacent ridges and troughs of the plurality of alternating ridges and troughs, at least 70%, 80%, or 90% of the length of the interface layer 40 along the first direction is coextensive with at least 70%, 80%, or 90% of the length of the ridges along the first direction.

[0032] In some embodiments, the second layer 32 is disposed at and in physical contact with the bottom 33 of the trench 30. In some embodiments, the second layer 32 is in physical contact with the sides 13, 14 of the ridge adjacent the bottom 33 of the trench 30. In some embodiments, the second layer 32 is disposed at and in physical contact with the top 21' of the ridge 20'. In some embodiments, for each pair of adjacent ridge and trench of the plurality of alternating ridges and trenches, no portion of the interface layer 40 is disposed on the bottom 33 (or 33') of the trench, and no portion of the interface layer 40 is disposed on the top 21 (or 21') of the ridge. In some embodiments, for each pair of adjacent ridge and trench of the plurality of alternating ridges and trenches, each of the bottom 33 (or 33') of the trench and the top 21 (or 21') of the ridge is substantially free of any light absorbing layer. For example, the bottom and the top can be completely free of any light absorbing layer, or can include a sufficiently small amount of light absorbing material such that the on-axis transmission of the light management film is not reduced by more than 10% (or 5% or 3%) compared to the same light management film without any light absorbing layer on the bottom and the top.

[0033] In some embodiments, each ridge 20 has opposing sidewalls 13 and 14. In some embodiments, for each sidewall of each ridge 20, the sidewall has a length Lt, the layer 40 covers a length LI of the sidewall, and the layer 32 covers a length L2 of the sidewall. Similarly, in some embodiments, each ridge 20' has opposing sidewalls 13' and 14'. In some embodiments, for each sidewall of each ridge 20', the sidewall has a length Lt, and the layer 40 covers a length LI of the sidewall. In some embodiments, the layer 32' (e.g., see Figure 2 ) is included and covers a length L2' of the sidewall. In some embodiments, LI / Lt is greater than about 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.85, 0.9, or 0.95. In some embodiments, LI / Lt' is greater than about 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.85, 0.9, or 0.95. In some embodiments, any one or more of L2 / Lt, L2' / Lt, L2 / Lt', or L2' / Lt' is less than about 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, 0.4, 0.3, 0.2, 0.1, 0.05, 0.04, 0.03, 0.02, or 0.01. For example, when the layer 32 along the sidewall is less wet (e.g., when formed using the method of Figures 11-13 ), L2 can be relatively small (e.g., L2 / Lt < 0.1), or when the layer 32 along the sidewall is more wet (e.g., when formed using the method of Figure 14 ), L2 can be relatively large (e.g., L2 / Lt > 0.1).

[0034] In some embodiments, in a cross-section of the light control film in a plane (xz plane) substantially normal to the light control film and the first direction, for each pair of adjacent ridge and groove of the plurality of alternating ridges and grooves, the interface layer 40 is disposed on one side of the ridge, where the side has a length Lt from the bottom of the groove to the top of the ridge, where the interface layer has a length LI along the side, and where the second layer 32 has a length L2 along the side. In some embodiments, L2 / Lt > 0.05, 0.1, 0.2, 0.3, or 0.4, and LI / Lt > 0.5. In some embodiments, LI / Lt > 0.6, 0.7, 0.8. In some embodiments, LI / Lt < 0.99, 0.98, 0.96, 0.94, or 0.92.

[0035] In some embodiments, each of the first and second layers has a maximum thickness ti, t2 greater than about 0.01 microns, 0.05 microns, 0.1 microns, 0.15 microns, 0.2 microns, 0.3 microns, 0.5 microns, 1 micron, 2 microns, 3 microns, 4, or 5 microns. In some embodiments, the maximum thickness ti of the first layer is at least 1.5 times, 2 times, 5 times, 10 times, 20 times, 50 times, 100 times, 150 times, or 200 times the maximum thickness t2 of the second layer. In some embodiments, the maximum thickness ti is less than about 1 mm. In embodiments where the first layer 31 is air, the maximum thickness of the first layer is understood to be the maximum thickness between the top 21 of the ridge 20 and the second layer 32 (e.g., the maximum thickness of the first layer can correspond to h2'). In embodiments where the first layer 31' is air, the maximum thickness of the first layer is understood to be the maximum thickness between the top 21' of the ridge 20' and the second layer 32' (if included) or the bottom 33' (if the second layer 32' is not included). In some embodiments, the second layer is less than about 10 microns, 9 microns, 8 microns, 7 microns, 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron thick. In some embodiments, the first layer is greater than about 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, or 90 microns thick.

[0036] In some embodiments, the optical film 10 is a polymeric optical film and the first layer 31 is a polymeric layer. Similarly, in some embodiments, the optical film 10' is a polymeric optical film and the first layer 31' is a polymeric layer. In some embodiments, the first layer has substantially the same first composition and the second layer has substantially the same second composition that is different from the first composition. In some embodiments, the first composition includes an acrylate. In some embodiments, the optical film has a unitary construction with a substantially uniform third composition. In some embodiments, the third composition includes an acrylate. The first and third compositions can be the same or different. In some embodiments, the second composition is different from each of the first and third compositions. In some embodiments, the second composition is such that the second layer is a release layer. In some embodiments, the light control film includes a plurality of discrete spaced apart release layers (32 and / or 32' in each of the trenches 30 and / or 30') embedded therein. In some embodiments, the second composition includes one or more of polyvinyl alcohol, silicone, wax, paraffin wax, hydrophobic material, fluorinated material, ethylene vinyl acetate, polyvinyl butyral, polylactic acid, and thermoplastic resin. Suitable silicone materials include, for example, photocurable silicones such as silicone (meth)acrylates. Exemplary useful silicone (meth)acrylates include mono- and polyfunctional silicone (meth)acrylates. Among these, silicone poly(meth)acrylates are preferred because they generally reduce the likelihood of unbound silicone (meth)acrylate after curing. Exemplary silicone (meth)acrylates include EBECRYL 350 silicone diacrylate and EBECRYL 1360 silicone hexaacrylate from Allnex, CN9800 aliphatic silicone acrylate and CN990 silicified urethane acrylate compound from Sartomer Co., and TEGO RC 702, TEGO RAD 2100, TEGO RAD 2250, and TEGO RAD 2500 silicone polyether acrylates from Evonik Industries, Parsippany, New Jersey.

[0037] In some embodiments, the first and second layers have a refractive index that differs by at least about 0.05, or 0.1, or 0.15, or 0.2, or 0.25, or 0.3, for at least one same visible wavelength in the visible wavelength range extending from about 420 nm to about 680 nm. In some embodiments, the refractive index differs by less than about 2, 1.5, or 1. In some embodiments, the first layer has a refractive index of less than about 1.3, 1.25, 1.2, or 1.15, or 1.1, or 1.05, for at least one visible wavelength in the visible wavelength range extending from about 420 nm to about 680 nm. In some embodiments, the first layer comprises primarily air. In some embodiments, the first layer comprises a nano-voided ultra-low refractive index material, such as those described in, for example, U.S. Patent Application Publication Nos. 2012 / 0038990 (Hao et al.), 2013 / 0011608 (Wolk et al.), and 2013 / 0235614 (Wolk et al.).

[0038] For example, the layer 40 can be formed via layer-by-layer (LbL) coating, chemical vapor deposition (CVD), sputtering, reactive sputtering, or atomic layer deposition (ALD). In some embodiments, the layer 40 is formed via LbL self-assembly, as described in, for example, U.S. Patent Application Nos. 2020 / 0400865 (Schmidt et al.); 2021 / 0333624 (Schmidt et al.); 2022 / 0019007 (Schmidt et al.); and 2023 / 00289558 (Liu et al.). Layers formed via LbL self-assembly typically include a plurality of polyelectrolyte layers. In some embodiments, the (interface) layer 40 includes a plurality of polyelectrolyte layers. In some embodiments, the plurality of polyelectrolyte layers contain organic and / or inorganic polyions and counterions. For example, in some embodiments, the plurality of polyelectrolyte layers contain organic polymeric polyions and counterions. In some embodiments, the plurality of polyelectrolyte layers contain light-absorbing materials. In some embodiments, the (interface) layer 40 includes a light-absorbing core layer disposed between a first cladding layer and a second cladding layer (e.g., as Figure 5 illustrated schematically in FIG. 1 for the layer 40'). Utilizing a suitable core layer and cladding layers can result in improved axial luminance of light passing through the film, with the luminance being more uniform over a viewing angle and with the cutoff viewing angle being sharpened, as described in, for example, U.S. Patent Application Nos. 2021 / 0333624 (Schmidt et al.) and 2023 / 00289558 (Liu et al.). In some embodiments, the core layer, as well as each of the first and second cladding layers, contains a plurality of polyelectrolyte layers.

[0039] LbL self-assembly is often used to electrostatically assemble films or coatings of oppositely charged polyelectrolytes, but other functional groups such as hydrogen bond donors / acceptors, metal ions / ligands, and covalently bonded moieties can be the driving force for film assembly. Some examples of suitable processes include those described in U.S. Patent Nos. 8,234,998 (Krogman et al.) and 8,313,798 (Nogueira et al.); U.S. Patent Application Publication Nos. 2011 / 0064936 (Hammond-Cunningham et al.); and 2020 / 0400865 (Schmidt et al.). For example, layer-by-layer dip coating can be performed using StratoSequence VI (nanoStrata Inc., Tallahassee, FL) dip coating robots. In some embodiments, the layer 40 includes a plurality of bilayers deposited by layer-by-layer self-assembly. The plurality of bilayers can be a stack of polyelectrolytes including organic (e.g., polymeric) and / or inorganic polyanions (e.g., cations) and counterions (e.g., anions). At least a portion of the cationic layers, at least a portion of the anionic layers, or a combination thereof can include a light-absorbing material (e.g., a pigment) ionically bound to the polyelectrolyte. The light-absorbing compound can be dispersed within at least a portion of the polyelectrolyte layers. A preferred light-absorbing material is carbon black, especially covalently surface-modified with sulfonate or carboxylate groups, or oxidized to generate carboxylate groups on the surface, for example. Such carbon black materials are commercially available from suppliers such as Cabot Corporation (Boston, Massachusetts), for example, under the trade designations CAB-O-JET 200, 300, 352K, and 400, and from Orient Corporation of America (Cranford, New Jersey), for example, under the trade designations BONJET CW-1, CW-2, and CW-3.

[0040] Suitable polymers containing a plurality of positively charged (or ionizable) groups (i.e., polycationic polyelectrolyte polymers) can be derived from these monomers, for example: Primary amino group-containing monomers and salts (e.g., hydrochlorides) thereof: vinylamine, allylamine, aminoalkyl(meth)acrylamide, aminoalkyl (meth)acrylate, 2-N-morpholinoalkyl (meth)acrylate; Secondary amino group-containing monomers and salts (e.g., hydrochlorides) thereof: alkylaminoalkylene (meth)acrylate, such as, for example, 2-(methylamino)ethyl (meth)acrylate; Monomers and salts (e.g., hydrochloride salts) containing tertiary amino groups: various N,N-dialkylaminoalkyl (meth)acrylates and N,N-dialkylaminoalkyl (meth)acrylamides, such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylate, and N,N-diethylaminopropyl (meth)acrylamide, (tert-butylamino)alkyl methacrylates, (tert-butylamino)alkyl acrylamides; and Monomers containing quaternary amino groups: methacrylamidopropyl trimethylammonium chloride, diallyldimethylammonium chloride, 2-acryloyloxyalkyl trimethylammonium chloride.

[0041] Some of the more common polycations used for layer-by-layer coating are: linear and branched poly(ethyleneimine) (PEI), poly(allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltrimethylammonium), poly(diallyldimethylammonium chloride) (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamido)propyl-trimethylammonium chloride, and combinations thereof, including copolymers thereof.

[0042] Suitable polycations can also include polymer latexes, dispersions, or emulsions having positively charged functional groups on the surface. Examples include Sancure 20051 and Sancure 20072 cationic polyurethane dispersions available from Lubrizol Corporation (Wickliffe, Ohio). Suitable polycations can also include inorganic nanoparticles (e.g., aluminum oxide, zirconium oxide, titanium dioxide) that are suitably below their natural isoelectric point, or alternatively surface-modified with positively charged functional groups.

[0043] Suitable polymers comprising a negatively charged ionogenic (or ionizable) group (i.e., polyanionic polyelectrolyte polymers) can be derived from these monomers (and salts thereof), for example: acid monomers: (meth)acrylic acid, beta-carboxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxysuccinic acid, vinylphosphonic acid, vinylsulfonic acid, styrene sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid, (meth)acrylic acid salts (i.e., zinc acrylate, zirconium acrylate, etc.), (meth)acrylic acid carboxyethyl ester salts (i.e., zirconium (meth)acrylic acid carboxyethyl ester), (meth)acrylic acid 2-sulfoalkyl esters, (meth)acrylic acid phosphonoalkyl esters, 2-hydroxyethyl methacrylate phosphonate.

[0044] Some of the more common polyanionic polymers for layer-by-layer coating are: poly(vinyl sulfate), poly(vinyl sulfonate), poly(acrylic acid) (PAA), poly(methacrylic acid), poly(styrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethyl cellulose, alginate, sulfonated tetrafluoroethylene-based fluoropolymers such as NAFION, poly(vinyl phosphonic acid), poly(vinyl phosphinic acid), and combinations thereof, including copolymers thereof.

[0045] Suitable polyanions can also include polymer latices, dispersions, or emulsions having negatively charged functional groups on the surface. Such polymers are commercially available, for example, under the trade name JONCRYL (BASF, Florham Park, New Jersey), under the trade name CARBOSET (Rohm and Haas, Wickliffe, Ohio), and under the trade name NEOCRYL (DSM Coating Resins, Wilmington, Massachusetts). Suitable anions can also include inorganic nanoparticles (e.g., silica, alumina, zirconia, titania, nanoclay) that are suitably above their natural isoelectric point, or alternatively, surface modified with negatively charged functional groups.

[0046] The thickness of the bilayers and the number of bilayers in the interface layer 40 can be selected to achieve desired optical properties (e.g., light absorption in the case of an optically absorbing core of the interface layer 40, or reduced reflection between the sidewalls and optically absorbing layers in the case of a cladding layer of the interface layer 40). In some embodiments, the thickness of the bilayers and / or the number of bilayers is selected to achieve the desired optical properties using a minimum total thickness of self-assembled layers and / or a minimum number of layer-by-layer deposition steps. The thickness of each bilayer is typically in the range of about 5 nm to 350 nm. The number of bilayers in the layer 40 is typically at least 5, 6, 7, 8, 9, or 10. In some embodiments, the number of bilayers in the layer 40 is no greater than 150 or 100. It will be appreciated that individual bilayers in the final article can not be distinguishable from one another by common methods in the art, such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM). In some embodiments, the thickness of the bilayers and the total number of bilayers is selected such that the total thickness of the layer 40 (e.g., the total thickness of any cladding layers and optically absorbing core layers) is less than, for example, about 2 microns, or 1.75 microns, or 1.50 microns, or 1.25 microns, or 1.00 microns, or 0.75 microns, or 0.50 microns, or 0.25 microns.

[0047] Figure 3 is a schematic cross-sectional view of an optical film 10 according to some embodiments. In some embodiments, in a planar cross-section (xz plane) of the light management film that is substantially orthogonal to the light management film (orthogonal to the xy plane) and the first direction (y direction), each of the ridges has opposing substantially straight first and second sides 13, 14 (e.g., any radius of curvature of the sides can be greater than 10, 50, or 100 times the height of the ridge). In some embodiments, each of the straight first and second sides forms an angle with the substantially planar major surface 12 of the light management film that is greater than about 80 degrees, or 82 degrees, or 84 degrees, or 85 degrees, or 86 degrees, or 87 degrees, or 88 degrees, or 89 degrees, or 89.5 degrees 1. In some embodiments, each of the ridges has a maximum width Wmax that is within 20%, 15%, 10%, or 5% of the minimum width Wmin of the ridge, in a planar cross-section (xz plane) of the optical film that is substantially orthogonal to the light control film and the first direction. In some embodiments, each of the ridges has a maximum width Wmax and a maximum height Hmax, where Hmax / Wmax > 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.5, 2, 3, 4, 5, 10, or 50, in a planar cross-section (xz plane) of the optical film that is substantially orthogonal to the light control film and the first direction. In some embodiments, each of Hmax, Wmax, and Wmin is in a range from about 0.05 microns to about 1 mm, or from about 0.1 microns to about 0.75 mm, or from about 0.2 microns to about 0.5 mm. In some embodiments, each of the ridges has a substantially polygonal shape, in a planar cross-section (xz plane) of the optical film that is substantially orthogonal to the light control film and the first direction. A substantially polygonal shape appears to be generally polygonal, but can have rounded corners or slightly rounded sides, e.g., with a radius of curvature that is small (e.g., less than about 10%) compared to other dimensions of the ridge (e.g., Wmin). For example, Figures 15-16 The ridges of FIG. 1 are substantially polygonal. In some embodiments, the polygonal shape is trapezoidal or rectangular.

[0048] In some embodiments, the optical film 10 includes a structured first major surface 15 opposite the second major surface 12, where the structured first major surface 15 is shaped to define alternating ridges 20 and troughs 30. In some embodiments, a minimum spacing t3 between the structured first major surface 15 and the second major surface 12 is greater than about 0.2 microns, or 0.5 microns, or 1 micron, or 2 microns, or 5 microns, or 10 microns. In some embodiments, the minimum spacing t3 is less than about 50 microns, or 45 microns, or 40 microns, or 35 microns, or 30 microns, or 25 microns, or 20 microns.

[0049] In some embodiments, the optical film 10' can have a similar geometry (e.g., a substantially polygonal shape) to the geometry of the optical film 10, where any one or more of Wmin, Wmax, Hmax, 1, t3 are within the same ranges described for the optical film 10.

[0050] Figure 4is a schematic cross-sectional view of a portion of an optical film (e.g., corresponding to optical film 10) having ridges with curved sidewalls according to some embodiments. In some embodiments, in a planar cross-section (xz plane) of the light control film substantially orthogonal to the light control film and the first direction, each of the ridges has opposing first and second sides 13, 14, where at least one of the first and second sides is curved. In some embodiments, at least one of the curved first and second sides forms a maximum angle with the substantially planar major surface 12 of the light control film that is greater than about 80 degrees, 82 degrees, 84 degrees, 85 degrees, 86 degrees, 87 degrees, 88 degrees, 89 degrees, or 89.5 degrees 1'. In the illustrated embodiment, each of the sidewalls 13, 14 of the ridges 20 are curved outward. The corresponding sidewalls of the ridges of the optical film 10' can be curved inward. Alternatively, the sidewalls of the ridges of the optical film 10 can be curved inward, and the sidewalls of the ridges of the optical film 10' can be curved outward. In some embodiments, only one of the sidewalls of the ridges 20 or 20' is curved, or one sidewall is curved outward and the other sidewall is curved inward.

[0051] Figure 5 is a schematic cross-sectional view of a portion of an optical film (e.g., corresponding to optical film 10) having trenches 30 with curved bottoms according to some embodiments. For example, the illustrated portion can repeat along the second direction (x direction). In some embodiments, in a planar cross-section (xz plane) of the light control film substantially orthogonal to the light control film and the first direction, each of the trenches includes a bottom portion 35 including a bottom 33 of the trench and opposing substantially straight sides 34 extending upward from opposing ends 35a of the bottom portion of the trench, where the second layer 32 conformally coats at least the bottom portion 35 of the trench (such that a bottom surface of the second layer 32 conforms to at least the bottom portion 35). In some embodiments, the bottom portion of each of the trenches is curved.

[0052] In some embodiments, for each pair of adjacent ridges and trenches of the plurality of alternating ridges and trenches, any light absorbing layer (corresponding to layer 40 or layer 40' or otherwise) that extends substantially coextensively along the first direction with the ridge and is disposed between the ridge and the second layer disposed in the trench has a maximum thickness that is less than about 0.05 microns, 0.04 microns, 0.03 microns, 0.02 microns, or 0.01 microns. In some embodiments, for each pair of adjacent ridges and trenches of the plurality of alternating ridges and trenches, no light absorbing layer is disposed between the ridge and the second layer disposed in the trench.

[0053] In some embodiments, the minimum spacing t3 between the bottom 33 of the trench and the nearest substantially planar major surface 12 of the light control film that extends substantially continuously across the entire width (x-direction) and the entire length (y-direction) of the light control film is greater than about 0.2 microns, 0.5 microns, 1 micron, 2 microns, 5 microns, or 10 microns. In some embodiments, the minimum spacing t3 is less than about 50 microns, 45 microns, 40 microns, 35 microns, 30 microns, 25 microns, or 20 microns.

[0054] In some embodiments, each of the interface layers 40' (e.g., corresponding to the layers 40) includes a light-absorbing core layer disposed between a first cladding layer and a second cladding layer, as Figure 5 schematically shown in FIG. 1 and as further described elsewhere herein.

[0055] Figures 6-7 is a schematic cross-sectional view of a light control film according to some embodiments, in which the second layer 32 covers portions of the sidewalls of the ridges 20. In some embodiments, as Figure 6 schematically shown in FIG. 1 for the light control film 500, for each sidewall, no portion of the layer 40 is disposed between the layer 32 and the sidewall. In some embodiments, as Figure 7 schematically shown in FIG. 1 for the light control film 700, for at least some of the sidewalls, a portion of the layer 40 is disposed between the layer 32 and the sidewall.

[0056] In some embodiments, in a planar cross-section (xz-plane) of the light control film substantially orthogonal to the light control film and the first direction, and for each of at least two trenches of the optical film, the trench includes opposing sides 34 extending upwardly from opposing end portions of the trench bottom, wherein the second layer 32 has a thicker middle portion 32a disposed between opposing thinner end portions 32b, wherein the thicker middle portion is disposed at the bottom 33 of the trench, and wherein the opposing thinner end portions are disposed on the opposing side portions of the trench.

[0057] Figures 8-9 is a schematic cross-sectional view of a light control film according to some embodiments, in which the second layer 32 covers portions of the top and sidewalls of the ridges 20'. The light control film 700, the light control film 800 includes an optical film 10' having a structured major surface 15' defining a plurality of alternating ridges 20' and valleys 30'. The layer 32 is disposed on the top 21 of the ridges 20' as well as adjacent portions of the sidewall 13' and the sidewall 14'. The ridges 20' with the layer 32 define a structure 120, which can have a substantially polygonal (e.g., trapezoidal or rectangular) shape. The layer 32 can be thin enough on the sidewall 13', the sidewall 14' such that the ridges 20' can also have, for example, a substantially trapezoidal or rectangular shape. In some embodiments, as Figure 8As schematically illustrated in FIG. 1, no portion of layer 32 is disposed between layer 40 and ridge 20'. In some embodiments, there can be a gap between layer 32 and layer 40 (see, e.g., FIG. 2). Figure 6 In some embodiments, there is substantially no gap between layer 32 and layer 40. In some embodiments, for example, as schematically illustrated in FIG. 3, a portion of layer 32 is disposed between layer 40 and ridge 20'. Figure 9 In some embodiments, there is substantially no gap between layer 32 and layer 40. In some embodiments, for example, as schematically illustrated in FIG. 3, a portion of layer 32 is disposed between layer 40 and ridge 20'.

[0058] A light control film can be described in terms of the ridges and grooves of the optical film. Alternatively or additionally, a light control film can be described in terms of the structures of the structured major surface. In some cases, the same layers can be referred to differently for different descriptions (e.g., interface layer vs. first layer).

[0059] In some embodiments, a light control film (300, 400, 500, 600, 700, 800, or other light control film described elsewhere herein) includes a structured major surface 15 (or 15') that extends continuously across the entire length (y-axis) and the entire width (x-axis) of the light control film and includes a plurality of structures 20 (or 20'), where each of the structures includes a top surface 21 (or 21') that extends between and joins opposing side surfaces 13, 14 (or 13', 14'). In some embodiments, the light control film is such that for each pair of adjacent first and second structures of the plurality of structures: a first side surface of the first structure faces a second side surface of the second structure; the first and second side surfaces are interconnected by a connecting surface portion (see, e.g., portion 35 illustrated in FIG. 1) of the structured major surface; a first layer 40 having a same first composition coats at least a majority of each of the first and second side surfaces; and a same second layer 32 (or 32') having a same second composition different from the first composition coats at least a majority of the connecting surface portion and coats adjacent portions of the first and second side surfaces. In some embodiments, the light control film is such that for each structure of the plurality of structures: a first layer 40 having a same first composition is disposed on and coextensive with at least a majority of each of the first and second side surfaces; and a second layer 32 (or 32') having a same second composition different from the first composition coats at least a majority of the top surface and coats portions of each of the first and second side surfaces adjacent to the top surface. Figure 5

[0060] ​In some embodiments, the light control film includes an optical film 10 shaped to define a structured major surface 15 (or an optical film 10' shaped to define a structured major surface 15'). In some embodiments, the optical film has a unitary construction having a substantially uniform third composition. The composition can be as described elsewhere herein. For example, in some embodiments, the third composition includes an acrylate. In some embodiments, the first composition includes a plurality of polyelectrolyte layers. In some embodiments, the second composition includes one or more of a polyvinyl alcohol, a silicone, a wax, a paraffin, a hydrophobic material, a fluorinated material, an ethylene vinyl acetate, a polyvinyl butyral, a polylactic acid, and a thermoplastic resin.

[0061] In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the structured major surface. In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer and the structured major surface. For example, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 500 schematically illustrated in FIG. 1A, while for each pair of adjacent first and second structures in the plurality of structures, some portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 600 schematically illustrated in FIG. 1C. Figure 6 In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the structured major surface. In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer and the structured major surface. For example, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 500 schematically illustrated in FIG. 1A, while for each pair of adjacent first and second structures in the plurality of structures, some portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 600 schematically illustrated in FIG. 1C. Figure 7 In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the structured major surface. In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer and the structured major surface. For example, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 500 schematically illustrated in FIG. 1A, while for each pair of adjacent first and second structures in the plurality of structures, some portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 600 schematically illustrated in FIG. 1C. Figures 11-12 In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the structured major surface. In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer and the structured major surface. For example, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 500 schematically illustrated in FIG. 1A, while for each pair of adjacent first and second structures in the plurality of structures, some portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 600 schematically illustrated in FIG. 1C. Figure 14 In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the structured major surface. In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer and the structured major surface. For example, for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 500 schematically illustrated in FIG. 1A, while for each pair of adjacent first and second structures in the plurality of structures, some portion of the first layer 40 is disposed between the second layer 32 and the structured major surface 15 of the light control film 600 schematically illustrated in FIG. 1C.

[0062] In some embodiments, for each pair of adjacent first and second structures of the plurality of structures, the second layer 32 (or 32') covers (e.g., coats) a portion of at least one of the first and second side surfaces adjacent the connecting surface portion 35. In some embodiments, for each pair of adjacent first and second structures of the plurality of structures, the second layer 32 covers (e.g., coats) a portion of each of the first and second side surfaces. In some embodiments, for each pair of adjacent first and second structures of the plurality of structures, and for each of the first and second side surfaces, the first layer 40 covers (e.g., coats) at least 50%, 60%, 70%, 80%, or 85% of the area of each of the first and second side surfaces. In some embodiments, for each pair of adjacent first and second structures of the plurality of structures, the second layer covers (e.g., coats) at least 60%, 70%, 80%, 90%, or 95% of the connecting surface portion 35.

[0063] In some embodiments, the structures 20 are arranged along a width direction (x-direction) and extend along an orthogonal length direction (y-direction) such that, in a cross-section of the light control film in a plane (xz-plane) substantially orthogonal to the light control film and the length direction, for each side surface of each structure of the plurality of structures, the side surface has a total length Lt, the first layer has a length LI along the side surface, and the second layer 32 (or 32') has a length L2 (or L2') along the side surface, where L2 / Lt (or L2' / Lt) is greater than 0.05 (or within a range described elsewhere herein) and LI / Lt > 0.5 (or within a range described elsewhere herein). In some embodiments, the maximum thickness of the second layer is less than 20%, 15%, 10%, 8%, 6%, 5%, 4%, 3%, 2%, or 1% of the total length Lt.

[0064] In some embodiments, structures of the plurality of structures cover at least a majority (more than 50% of the total area in a top plan view) of the structured major surface. In some embodiments, structures of the plurality of structures cover at least 60%, 70%, 80%, 85%, or 90% (by area in a top plan view) of the structured major surface.

[0065] In some embodiments, structures of the plurality of structures are arranged as a regular array of structures. In some embodiments, structures of the plurality of structures are substantially linear structures extending along a same first direction (y-direction) and arranged along an orthogonal second direction (x-direction). In some embodiments, the first direction is substantially along a length of the light control film. In some embodiments, the first layer 40 substantially coextends along the first direction with each of the first and second side surfaces. In some embodiments, the second layer substantially coextends along the first direction with the connecting surface portion 35.

[0066] In some embodiments, the first layer 40 has an average thickness t along a thickness direction of the light control film that is orthogonal to each of a length direction and a width direction of the light control film, and an average height hi, where hi / t 10 (or within a range described elsewhere herein).

[0067] In some embodiments, the first layer 40 is optically absorptive. In some embodiments, the first layer 40 has an optical density greater than about 0.1, or 0.2, or 0.3, or 0.4, or 0.5, or 0.75, or 1, or 1.5, or 2. The optical density of a layer is the negative of the base-10 logarithm of the transmittance through the layer, where transmittance is understood to be the average transmittance of normally incident light over a wavelength range of about 420 nm to 680 nm, unless otherwise specified. In some embodiments, the first layer 40 is optically absorptive and the second layer 32 (or 32’) is a release layer. In some embodiments, for each of the plurality of structures and each of the first and second side surfaces of the structure, the first layer is substantially permanently bonded to a bottom portion of the side surface rather than a top portion, where the top portion is disposed between the top surface and the bottom portion. In some embodiments, for each of the plurality of structures and each of the first and second side surfaces of the structure, a bottom portion of the first layer is substantially permanently bonded to the side surface rather than a top portion, where the top portion is disposed between the top surface and the bottom portion. In some embodiments, for each of the plurality of structures, the second layer is a release layer, and for each of the first and second side surfaces, the first layer is optically absorptive and substantially permanently attached to the side surface. In some embodiments, for at least one side surface of each of at least some of the plurality of structures, the first layer at least partially covers the release layer. For example, for each of the plurality of structures, the first layer can be optically absorptive and substantially permanently attached to the first side surface and the second side surface. Figure 9 For the light control film 800 schematically shown in FIG. 8, the layer 40 can be permanently attached to a bottom portion of a side surface of the structure 20, but an upper portion of the layer 40 can not be permanently attached to the side surface when the layer 32 is a release layer. A layer is substantially permanently bonded or attached to an element when it cannot be removed from the element without causing significant damage (e.g., breaking or cracking) to at least one of the layer or the element. Each layer 40 can be substantially permanently attached directly to a side surface of a structure of the plurality of structures.

[0068] In some embodiments, the third layer 31 (or 31') is disposed over the structured major surface 15 (or 15') and substantially fills the space between adjacent structures of the plurality of structures. In some embodiments, for each structure of the structure, no portion of the third layer is disposed between the structure and either the first layer or the second layer. The third layer can be, for example, an air layer or a polymeric layer. In some embodiments, air substantially fills the space between adjacent structures of the plurality of structures. In some embodiments, the third layer comprises a polymeric layer having a second structured major surface (e.g., 15) substantially conforming to (e.g., nominally conforming to or conforming to variations of, for example, less than 10% of Wmin) the first structured major surface (e.g., 15') and an opposing substantially planar major surface (e.g., Figure 2 shown schematically in FIG. 12'). In some embodiments, the polymeric layer has a third composition different from each of the first and second compositions (of the respective first and second layers). In some embodiments, no more than 80 area%, 70 area%, 60 area%, 50 area%, 40 area%, 30 area%, 20 area%, 10 area%, 5 area%, 4 area%, 3 area%, 2 area%, or 1 area% of the first layer 40 is disposed between the second layer 32 (or 32') and the second structured major surface. In some embodiments, no portion of the first layer is disposed between the second layer and the second structured major surface.

[0069] Figure 10 is a schematic cross-sectional view of a light control film 900 disposed proximate to a light source 50 according to some embodiments. The light control film 900 can correspond to any of the light control films of the present description. In some embodiments, the (interface or first) layer 40 is substantially light absorbing, having an optical density greater than about 0.1 (or within the ranges described elsewhere herein). When the layer 40 is light absorbing, the light control film can effectively limit the angular range of light transmitted through the light control film. In some embodiments, when light 51 from a substantially Lambertian light source 50 is incident on the light control film 900, the light control film 900 transmits the incident light, with the transmitted light 52 having an intensity distribution in a substantially orthogonal to the plane cross-section (xz-plane) of the light control film and first direction (y-direction) having a full width at half maximum (FWHM) of less than about 120 degrees, 110 degrees, 100 degrees, 90 degrees, 80 degrees, 75 degrees, 70 degrees, 65 degrees, 60 degrees, 55 degrees, 50 degrees, or 45 degrees. In some embodiments, the (interface or first) layer 40 has a high aspect ratio (e.g., h1 / t 10or described elsewhere herein), such that the light control film substantially transmits on-axis visible light. In some embodiments, the light control film 900 has an average on-axis luminous reflectance of at least about 65%, 70%, 75%, 80%, or 85% in the wavelength range of about 420 nm to about 680 nm.

[0070] Figure 11 The initial steps of a process for manufacturing a light control film according to some embodiments are schematically illustrated. Figure 12 Steps of a process for manufacturing a light control film, such as, for example, light control film 300 or light control film 500, according to some embodiments are schematically illustrated. Figure 13 Steps of a process for manufacturing a light control film, such as, for example, light control film 400, according to some embodiments are schematically illustrated.

[0071] In some embodiments, a method of manufacturing a light control film includes the following steps. Step 1 (a)-(b) in Figure 11 with respect to a first film 301 having a first structured major surface comprising a plurality of first structures 210 arranged along a first direction (x-direction) and defining a plurality of first channels 222 extending along an orthogonal second direction (y-direction), wherein each first channel is disposed between adjacent first structures and has an open top 214 opposite a bottom 216 of the first channel, and wherein each of the first structures has a top surface 212 extending between and joining opposite side surfaces of the first structure, coating a release layer 360 onto the top surfaces of the first structures. For example, the release layer 360 can be deposited onto the top surfaces of the first structures 210 via direct or flexographic gravure coating, roll coating, brush coating, dip coating, slot dye coating, inkjet printing, flexographic printing, or gravure printing. Step 2: substantially filling each of the plurality of first channels with a resin. Step 3: solidifying (e.g., by curing a radiation-curable resin or cooling a molten resin) the resin to form a second film 401 comprising a platform portion 410 and a second structured major surface 601 comprising a plurality of second structures 610, wherein each second structure extends from the platform portion to a top surface 612 of the second structure, and wherein the top surface extends between and joins opposite side walls 714 and 715 of the second structure. Step 4: separating the first film and the second film such that the second film comprises the release layer disposed on the platform portion. (Steps 2-4 can correspond to the manufacture of a film (b) from a film (a) of Figure 11 Figure 12 ). Step 5 (a)-(b) in Figure 12 deposits an optically absorbing layer 250 onto the second structured major surface such that the optically absorbing layer substantially conforms to the second structured major surface. Step 6 (a)-(b) in​Figure 12 (b) to (c) in FIG. 8): removing the optically absorbing layer from the top surface of the second structure and from the release layer. The optically absorbing layer can be removed from the top surface, for example, by wetting the surface with water and rubbing with a horsehair brush, or by peeling the optically absorbing layer using a tape. The optically absorbing layer can be removed from the bottom surface (the surface of the release layer), for example, using an ultrasonic cleaning bath. The remaining portion of the optically absorbing layer 250 can correspond to the layer 40 described elsewhere herein. Steps 1-6 can be performed sequentially.

[0072] In some embodiments, the optically absorbing layer remaining on the sidewalls of the second structure has an average height hi in a height direction substantially normal to the first and second directions and has an average thickness t, where hi / t 10 (or within a range described elsewhere herein).

[0073] In some embodiments, the method further comprises, between the separating step (step 4) and the step of depositing an optically absorbing layer (step 5, which can correspond to Figure 13 (a) to (b) in FIG. 7): applying a release layer to the top surface of the second structure. This can result in, for example, the second film 401' of FIG. 8. Figure 13 In some embodiments, the method further comprises, between the separating step (step 4) and the step of depositing an optically absorbing layer (step 5, which can correspond to Figure 13 As indicated by the change from (b) to (c) in FIG. 8, the release layer on the top surface can facilitate removal of the optically absorbing layer from the top surface.

[0074] In some embodiments, the method further comprises, prior to the applying step (step 1): forming a microreplication layer having a microstructured major surface; and surface treating the microstructured major surface to provide the first structured surface of the first film 301. Suitable surface treatments include treatment with organosilicon compounds such as hexamethyldisiloxane (HMDSO). The HMDSO can be applied via plasma deposition, for example. In some embodiments, the microreplication layer is formed on a first substrate 160, and the second film 401 is formed on a second substrate 160'.

[0075] In some embodiments, the method further comprises, after removing the optically absorbing layer from the top surface of the second structure and from the release layer (step 6), forming a planarization layer on the second structured major surface (e.g., by backfilling with resin and then solidifying the resin), where the planarization layer has a major surface substantially conforming to the second structured major surface and an opposing substantially planar major surface. The planarization layer can correspond to the layer 31 of FIG. 7, for example. Figures 1-2 Figures 5-7 or Figure 10 the layer 31 of FIG. 7.

[0076] Figure 14 ​A process for manufacturing a light control film, such as, for example, light control film 300, light control film 500, light control film 600, light control film 700, or light control film 800, is schematically illustrated in accordance with some embodiments. In some embodiments, the method of manufacturing a light control film includes the following steps. Step 1 (a)-(b) in Figure 14 : depositing an optically absorbing layer 250 onto a first structured major surface of a first film 301 such that the optically absorbing layer substantially conforms to the first structured major surface, wherein the first structured major surface includes a plurality of first structures 210 arranged along a first direction (x-direction) and defining a plurality of first channels 222 extending along an orthogonal second direction (y-direction), and wherein each first channel is disposed between adjacent first structures and has an open top portion 214 opposite a bottom portion 216 of the first channel. Step 2 (b)-(c) in Figure 14 : removing the optically absorbing layer from a top portion 212 of each first structure of the plurality of first structures, wherein the top portion of the first structure is adjacent the open top portion of the first channel. This can be accomplished, for example, by wetting the surface with water and rubbing with a horsehair brush, or by peeling the optically absorbing layer with a tape. Step 3 (c)-(d) in Figure 14 : for each first channel of the plurality of first channels, disposing a release layer 360 on the optically absorbing layer along the bottom portion of the first channel and along at least a portion of the sidewalls of the first structures adjacent the first channel. The release layer 360 can be deposited, for example, via a wire-wound rod, slot dye coating, notched bar coating, gravure coating, spray coating, or inkjet printing. Step 4: after the removing and disposing steps (steps 2 and 3), substantially filling each first channel of the plurality of first channels with a resin. Step 5: solidifying the resin to form a second film 401 including a platform portion 410 and a second structured major surface including a plurality of second structures 610, wherein each second structure extends from the platform portion to a top portion 612 of the second structure, and wherein the top portion extends between and joins opposite sidewalls 714 and 715 of the second structure. Step 6: separating the first film and the second film such that the second film includes the optically absorbing layer disposed on the sidewalls and top portion of the second structures. (Steps 4-6 can correspond to variations of (d)-(e) in Figure 14 ). Step 7 (f)-(g) in Figure 14 : for each second structure of the plurality of second structures, removing the optically absorbing layer from at least the top portion of the second structure to expose the release layer. The optically absorbing layer can be removed from the top surface, for example, by wetting the surface with water and rubbing with a horsehair brush, or by peeling the optically absorbing layer with a tape, or by using a layer of resin coated on the substrate and cured in contact with the optically absorbing layer to peel the optically absorbing layer, as described in Figure 14Step (f) of the method 200 is schematically illustrated. The remaining portion of the optically absorbing layer 250 can correspond to the layer 40 described elsewhere herein. Steps 1-7 can be performed sequentially.

[0077] In some embodiments, the optically absorbing layer remaining on the sidewalls of the second structure has an average height hi in a height direction substantially orthogonal to the first and second directions and has an average thickness t, where hi / t 10 (or within a range described elsewhere herein).

[0078] In some embodiments, the method includes, prior to the depositing step (step 1): forming a microreplication layer having a microstructured major surface; and surface treating the microstructured major surface to provide the first structured surface of the first film 301. Suitable surface treatments include treatment with organosilicon compounds such as hexamethyldisiloxane (HMDSO). For example, the HMDSO can be applied via plasma deposition. In some embodiments, the microreplication layer is formed on the first substrate 160 and the second film 401 is formed on the second substrate 160'.

[0079] In some embodiments, disposing the release layer on the optically absorbing layer for each of the plurality of first channels 222 and for each of the sidewalls adjacent the first channels includes disposing the release layer on no more than about 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10% of a height of the optically absorbing layer along the height direction along the sidewalls. In some embodiments, disposing the release layer on the optically absorbing layer for each of the plurality of first channels 222 and for each of the sidewalls adjacent the first channels includes disposing the release layer on at least 2%, 5%, 10%, 15%, 20%, 25%, or 30% of a height of the optically absorbing layer along the height direction along the sidewalls.

[0080] In some embodiments, substantially filling each of the plurality of first channels with the resin (step 4) includes overcoating the first structured surface with the resin.

[0081] In some embodiments, the method includes, after removing the optically absorbing layer from at least the top portion of the second structure (step 2), forming a planarization layer on the second structured major surface, the planarization layer having a major surface substantially conforming to the second structured major surface and an opposing substantially planar major surface. The planarization layer can correspond to, for example, the layer 31' of the method 300, or to, for example, the optical film 10 of the method 400. Figures 8-9 Figures 1-2 or the optical film 10 of the method 400. Figures 6-7

[0082] In some embodiments, the method 200 includes, prior to the depositing step (step 1): forming a microreplication layer having a microstructured major surface; and surface treating the microstructured major surface to provide the first structured surface of the first film 301. Suitable surface treatments include treatment with organosilicon compounds such as hexamethyldisiloxane (HMDSO). For example, the HMDSO can be applied via plasma deposition. In some embodiments, the microreplication layer is formed on the first substrate 160 and the second film 401 is formed on the second substrate 160'. Figures 12-14 ​​In this method, the deposition of the optical absorption layer 250 can be performed using any suitable deposition technique. Various coating methods that can be used include, for example, layer-by-layer (LbL) coating, chemical vapor deposition (CVD), sputtering, reactive sputtering, and atomic layer deposition (ALD). In some embodiments, in Figures 12-14 In any method, the deposition of the optical absorption layer 250 can be performed via LbL self-assembly, as described below: for example, U.S. Patent Application No. 2021 / 0333624 (Schmidt et al.); No. 2022 / 0019007 (Schmidt et al.); and No. 2023 / 00289558 (Liu et al.).

[0083]

[0084] Example 1

[0085] “Cast and Cure” UV microplication of film tool

[0086] Using diamond (29.0μm tip width, 3) A metal tool with multiple parallel linear grooves (angled, 87 μm deep) is cut. The grooves are spaced at a pitch of 62.6 μm. A roll of UV microreplication film is produced using resin A, which is prepared by mixing the materials in the table below, to form a replica of the tool.

[0087]

[0088] The microreplication process, involving casting and curing, was performed using the aforementioned resin A and tools. Linear conditions were as follows: resin temperature 150℉ (65.6℃), mold temperature 150℉ (65.6℃), coating machine IR 120℉ (48.9℃) edge / 130℉ (54.4℃) center, tool temperature 100℉ (37.8℃), and linear speed 70 feet per minute (fpm) (0.36 meters per second (m / s)). Curing was performed using a Fusion D lamp with a peak wavelength of 385 nm and operated at 100% power. The resulting microstructured film comprised multiple protrusions separated by channels. The substrate layer was a 2.93 mil (74.4 micrometer) thick PET film (3M Company, St. Paul, MN). The resin-contacting side of the PET film was primed with a thermosetting acrylic polymer (RHOPLEX 3208, purchased from Dow Chemical, Midland, MI). The thickness of the cured resin plateau layer was 8 micrometers. The protrusions of the microstructured film are negative copies of the tool grooves. The protrusions have a 1.5-degree wall angle, resulting in a slight taper. The channels of the microstructured film are negative copies of the uncut portions of the tool between the grooves.

[0089] HMDSO release treatment of microchannels : A custom-made parallel-plate capacitively-coupled plasma reactor was used to deposit a release treatment onto a UV microreplicated channel film from "Cast and Cure" UV microreplication by "Film Tool" as described in U.S. Patent No. 6,696,157 (David et al.). The chamber has a central cylindrical powered electrode with a surface area of 18.3 ft 2 After the film was placed on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). In the first step, the film was exposed to an oxygen etch, where O2 flowed into the chamber at a rate of 1000 sccm, the RF power frequency was 13.56 MHz and the applied power was 2000 W. The etch exposure was controlled via a line speed of 30 fpm, resulting in an approximate etch time of 10 seconds. The oxygen was turned off, and HMDSO gas was introduced into the chamber at an RF power of 2000 W. The film was then run backward through the reactor at 20 fpm, resulting in an approximate HMDSO release treatment time of 15 seconds. Upon completion of the treatment, the RF power and gas supply were stopped and the chamber was returned to atmospheric pressure.

[0090] Printing of release layer and replication from film tool

[0091] The upper horizontal surface of the HMDSO treated microreplicated channel film (e.g., film 301 corresponding to Figure 11 was selectively coated and partially cured with a release ink. TEGO 702 was used as the release ink and was applied via roll-to-roll gravure coating, utilizing a 1.0 BCM / inch 2The gravure roll was deposited at 5 ft / min. The release patterned substrate was then conveyed through a 385 nm UV LED array, the output irradiance of which was controlled by setting the power supply current to 8 amps, the result of which was to partially solidify (or cure) the patterned release layer on the upper horizontal surface of the HMDSO treated microstructured substrate. The partially cured release coated microstructured substrate was then conveyed to the back end of the coating line where a backfill "cast and cure" microreplication process step was performed using Resin A. The substrate was conveyed through the line until the section before the lamination nip against a temperature controlled support roll. A peristaltic pump (Watson Marlow 505 UD) was set up with 1 / 8" tubing at 5 RPM to deliver the solution to the center of the release coated microstructured channel film via a point source. The film was conveyed into a 90-hardness meter rubber roll that was clamped against a steel roll set to 130 °F with an air cylinder (Bimba, University Park, IL) at 40 psi pressure. 5 mil ST504 (DuPont, Midland, MI) PET was laminated to the release coated film with Resin A spreading to the extent of the pattern while filling the release coated film tool. The film stack was then cured via a Fusion D bulb (Heraeus, Hanau, Germany) and the two films were separated after the UV curing process. The transfer film was used to impart an inverted structure, resulting in a clear channel film (e.g., corresponding to Figure 12 Film 401) with the TEGO 702 release coating transferred to the bottom of the channels. The resulting "clear channel film" made from Resin A on 5 mil PET was then conveyed to a winder and wound into a roll.

[0092] Layer-by-layer coating on transparent channel film

[0093] Three separate coating solutions were prepared: cationic and core anionic, and overcoat anionic. The cationic solution was 2.5% solids SANCURE 20072 (cationic polyurethane dispersion from Lubrizol Corp.) with 200 mM sodium chloride (NaCl) and 0.1% PLURONIC L92 (PL92) (non-ionic surfactant from BASF). The core anionic solution was 2.5% solids EXPCB (anionically surface-modified carbon black from Cabot) with 50 mM NaCl and 0.1% PL92. The overcoat anionic solution was 4.0% solids CARBOSET CR-3090 (anionic styrene-acrylate emulsion from Lubrizol Corp.), 0.5% solids EXPCB, 50 mM NaCl, and 0.1% PL92. The coating architecture was overcoat core, as described in U.S. Patent Application No. 2021 / 0333624 (Schmidt et al.). Six cationic / overcoat anionic bilayers were deposited, followed by four cationic / core anionic bilayers, followed by six cationic / overcoat anionic bilayers, for a total of 16 bilayers. The black coating was conformally coated on a clear channel film via layer-by-layer (LbL) deposition using a spray coater from Svaya Nanotechnologies, Inc. (Sunnyvale, CA), and following the system described in U.S. Patent No. 8234998 (Krogman et al.) and Krogman et al. “Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition” (Langmuir, 2007, Vol. 23, pp. 3137-3141). The apparatus included pressure vessels loaded with the coating solutions. Spray nozzles (purchased from Spraying Systems, Inc., Wheaton, IL) with flat spray patterns were installed to spray the coating solutions and rinse water at designated times controlled by solenoid valves. The pressure vessels containing the coating solutions (Alloy Products Corp., Waukesha, WI) were pressurized to 30 pounds per square inch (psi) (0.21 MPa) with nitrogen while the pressure vessel containing DI water was pressurized to 30 psi (0.21 MPa) with air. The flow rates of the coating solution nozzles were each 10 gallons per hour (38 liters per hour), while the flow rate of the DI water rinse nozzle was 40 gallons per hour (150 liters per hour).A substrate to be coated (9 inch x 12 inch) (23 cm x 30 cm) was adhered to a glass plate (12 inch x 12 inch x 1 / 8 inch thick) (30 cm x 30 cm x 0.3 cm) (Brin Northwestern Glass Co., Minneapolis, MN) at the edges with epoxy (Scotch-Weld Epoxy Adhesive, DP100 Clear, 3M Company, St. Paul, MN) and mounted on a vertical translation stage and held in place with vacuum chucks. In a typical coating sequence, the polycation solution was sprayed onto the substrate while the stage was moved vertically downward at 76 mm / sec. Next, DI water was sprayed onto the substrate after a 12 second dwell time while the stage was moved vertically upward at 102 mm / s. The substrate was then dried with an air knife at a speed of 3 mm / s. Next, the polyanion solution was sprayed onto the substrate while the stage was moved vertically downward at 76 mm / s. Another dwell time of 12 s was allowed. DI water was sprayed onto the substrate while the stage was moved vertically upward at 102 mm / s. Finally, the substrate was dried with an air knife at a speed of 3 mm / s. The above sequence was repeated to deposit multiple "bilayers" denoted as (polycation / polyanion)n, where n is the number of bilayers. The coated substrate (e.g., polymer film) was peeled from the glass after which subsequent processing was performed.

[0094] Removal of LbL coating from upper horizontal surface

[0095] After LbL coating of the channel film with release material (TEGO 702) selectively in the recesses of the microstructured substrate, it was desirable to first remove the LbL coated opaque layer from the upper horizontal surface. This was simply done by depositing a generous amount of DI water on the surface of the LbL coated substrate and gently rubbing the surface with a horsehair brush (All Printing Resources, Glendale Heights, IL) for about 30 seconds until the upper surface was visibly free of the LbL coated opaque layer.

[0096] Removal of LbL coating from lower horizontal surface

[0097] After removing the LbL coating from the top horizontal surface, the LbL coating was removed from the bottom horizontal surface. This was done by placing the sample in a bench top ultrasonic cleaning bath (Crest, Ewing, NJ) consisting of 40 g Altra wash green (Harper, De Pere, WI) and 1500 g tap water. The bath temperature was set to 30 °C and the ultrasonic power was set between 1 and 3. The sample was left in the bath for about 1 to 2 minutes until it appeared that the sample was free of any material at the bottom of the channel. SEM images of the washed film are shown in Figure 15 It can be seen that the LbL coating is no longer on the bottom horizontal surface. The resulting light management film had a total transmission of 88% as measured by HazeGard II (BYK-Gardner, Geretsried, Germany).

[0098] Example 2

[0099] Resin B was prepared by mixing the materials in the table below.

[0100]

[0101] Formation of microchannels

[0102] The microchannel film used for these experiments (e.g., film 301 corresponding to Figure 14 was formed by "cast and cure" UV microreplication of Resin B onto PET using the same metal tooling and similar processing conditions as described in Example 1.

[0103] HMDSO release treatment of microchannels

[0104] A home-built parallel-plate capacitively coupled plasma reactor was used to deposit a release treatment onto the microchannel film from "Formation of Microchannels" as described in U.S. Patent No. 6,696,157 (David et al.). The chamber had a surface area of 18.3 ft 2centered cylindrical powered electrode. After the membrane was placed on the powered electrode, the reaction chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). In the first step, the membrane was exposed to an oxygen etch, where O2 flowed into the chamber at a rate of 1000 SCCM, the RF power frequency was 13.56 MHz, and the applied power was 2000 W. The etch exposure was controlled via a line speed of 30 fpm, resulting in an approximate etch time of 10 seconds. The oxygen was turned off, and HMDSO gas was introduced into the chamber with an RF power of 2000 W. The membrane was then run backward through the reactor at 20 fpm, resulting in an approximate HMDSO release treatment time of 15 seconds. Upon completion of the treatment, the RF power and gas supply were stopped and the chamber was returned to atmospheric pressure.

[0105] Layer-by-layer deposition of opaque (carbon black) conformal coating

[0106] After the release treatment of the microchannel membrane, an opaque conformal coating was deposited on the surface of the HMDSO treated microchannel membrane. The conformal layer was deposited by layer-by-layer (LbL) deposition. Three separate coating solutions were prepared: cationic, core anionic, and sheathing anionic. The cationic solution was 2.5% solids SANCURE 20072 (cationic polyurethane dispersion from Lubrizol) with 200 mM sodium chloride (NaCl) and 0.1% PLURONIC L92 (PL92) (non-ionic surfactant from BASF). The core anionic solution was 2.5% solids EXPCB (anionically surface-modified carbon black from Cabot) with 50 mM NaCl and 0.1% PL92. The sheathing anionic solution was 4.0% solids CARBOSET CR-3090 (anionic styrene acrylic emulsion from Lubrizol), 0.5% solids EXPCB, 50 mM NaCl, and 0.1% PL92. The coating architecture was sheathing core, as described in U.S. Patent Application No. 2021 / 0333624 (Schmidt et al.). A length of about 125 feet of microstructured membrane was passed through a continuous LbL coater. Six cationic / sheathing anionic bilayers were deposited, followed by four cationic / core anionic bilayers, followed by six cationic / sheathing anionic bilayers, for a total of 16 bilayers. At each coating station, the solution, which was fed with a needle from a liquid delivery manifold, was coated onto the microstructured membrane with a #4 Mayer Rod at a flow rate of about 200 mL / min. Excess coating solution was removed from the web with an air knife at a distance of 40 mils from the web at a pressure of about 35 psi. The line speed was 50 feet / minute. The resulting opaque coating was about 1 micron thick, as measured by cross-sectional scanning electron microscopy (SEM).

[0107] Adhesive transfer of opaque coating from first upper surface of microchannel film

[0108] The opaque conformable film was removed from the (first) upper surface of the LbL coated and HMDSO treated microchannel film using 3M Magic Tape. The adhesive was laminated to the upper surface and then peeled, which easily and cleanly removed the opaque coating from the microchannel upper surface.

[0109] Coating of release layer

[0110] A release layer was coated onto the LbL coated HMDSO treated channel film. A solution of 5% PVA (9000 MW to 10000 MW 99% hydrolyzed, Sigma-Aldrich) in DI water was coated with a #3 Meyer Bar. The coating was dried in an oven at 180F for 2 minutes.

[0111] Inversion of microchannel film to form sub-body with transferred opaque coating

[0112] The remaining opaque film (covering the HMSDO treated channel sidewalls and bottom) was transferred to a replica body substrate. This was accomplished by lamination of an extruded film of photocurable resin between the sample from the "coating of a release layer" and a 5 mil thick nanoscabbed PET film using a ChemInstruments hot roll laminator. The laminated stack was transported via a conveyor through a Fusion mercury arc lamp configured with a H bulb to solidify the photocurable resin. The hardened laminated stack was separated by peeling the PET from the laminated stack to form a body replica in the cured resin with three sides of the microchannel covered by the opaque coating. The opaque coating now covers the sidewalls and upper surface of the replicated body substrate (e.g., as schematically shown in film (e) in Figure 14 ).

[0113] Removal of opaque coating from second upper surface of sub-body microchannel film

[0114] A film of nanoscabbed PET film was coated with about 3 microns of resin A by coating a 50 wt% solution of resin A in MEK with a #3 Meyer Bar. This PET film was laminated to the body film from the "inverted microchannel film to form a body with transferred opaque coating" using a ChemInstruments hot roll laminator at zero additional applied pressure at a motor speed of 1. The film was then cured using a Fusion mercury arc lamp with a H bulb and used to remove the optically absorbing layer (i.e., the opaque coating) from the upper surface and upper portion of the sidewalls. Figure 16 is an SEM image of the resulting light control film. The coaxial transmittance of the light control film was measured to be 75% to 78% using a HazeGard II.

[0115] Terms such as“about” will be understood by those of ordinary skill in the art in the context in which they are used and described in this specification. If the use of“about” to an expressed quantity of a size, amount, and physical property is not clear to one of ordinary skill in the art in the context in which it is used and described in this specification, then“about” will be understood to mean within 10% of the designated value. A quantity given as about a designated value can be exactly the designated value. For example, if it is not clear to one of ordinary skill in the art in the context in which it is used and described in this specification, a quantity having a value of about 1 means that the quantity has a value between 0.9 and 1.1, and the value can be 1.

[0116] The term such as“substantially” will be understood by those of ordinary skill in the art in the context in which it is used and described in this specification. If the use of“substantially” with respect to a property or characteristic is not clear to one of ordinary skill in the art in the context in which it is used and described in this specification, and when it is clear to one of ordinary skill in the art that the opposite meaning of the property or characteristic is intended, then the term“substantially” will be understood to mean that the property or characteristic is exhibited to a greater degree than the opposite meaning of the property or characteristic.

[0117] All cited references, patents and patent applications in the above paragraph are herein incorporated by reference in their entirety to the same extent as if each individual citation was specifically and individually indicated to be incorporated by reference in its entirety. In the event that there is a conflict between the information contained in such incorporated references and that contained in the present specification, the present specification shall control.

[0118] Unless otherwise indicated, descriptions of elements in the figures should be understood to apply equally to corresponding elements in other figures. While specific embodiments have been illustrated and described, it will be appreciated that various alternate and / or equivalent modifications can be made of the embodiments described without deviating from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be protected by the following claims and their equivalents.

Claims

1. A light-controlling film comprising an optical film shaped to define a plurality of substantially linearly alternating ridges and grooves extending along substantially the same first direction and arranged along orthogonal second directions, each of the grooves comprising a first layer and a second layer disposed therein and stacked along the thickness direction of the light-controlling film, each of the first layer and the second layer having a maximum thickness greater than about 0.01 micrometers, the second layer being disposed between the first layer and the bottom of the groove. For each pair of adjacent ridges and grooves in a plurality of alternating ridges and grooves, an interface layer extending substantially co-located with the ridge along the first direction is disposed between the ridge and the first layer disposed in the groove, such that at least a portion of the second layer is not separated from the ridge by the interface layer, the interface layer having a maximum thickness greater than about 0.01 micrometers and less than about 10 micrometers.

2. The light-controlled film according to claim 1, wherein for each pair of adjacent ridges and grooves of the plurality of alternating ridges and grooves, no portion of the interface layer is disposed between the ridge and the second layer.

3. The light control film according to claim 1, wherein in a plane cross-section of the optical film substantially orthogonal to the light control film and the first direction, each of the ridges has a maximum width that differs from the minimum width of the ridge by no more than 20%.

4. The light control film according to claim 1, wherein the second layer is less than about 10 micrometers thick, and the first layer is greater than about 10 micrometers thick.

5. The light control film according to claim 1, wherein the first layer has a substantially identical first composition, and the second layer has a substantially identical second composition different from the first composition.

6. The light-control film according to claim 5, wherein the first composition comprises acrylate, and the second composition comprises one or more of polyvinyl alcohol, silicone, wax, paraffin, hydrophobic material, fluorinated material, ethylene vinyl acetate, polyvinyl butyral, polylactic acid, and thermoplastic resin.

7. The light-controlling film of claim 1, wherein for each pair of adjacent ridges and grooves of the plurality of alternating ridges and grooves, the bottom of the groove and the top of the ridge are substantially free of any light-absorbing layer.

8. The light-controlling film according to claim 1, wherein the interface layer is substantially light-absorbing and has an optical density greater than about 0.

1.

9. A light-controlling film, the light-controlling film comprising a structured main surface extending substantially continuously over the entire length and width of the light-controlling film and comprising a plurality of structures, each of the structures comprising a top surface extending between opposing side surfaces and engaging the opposing side surfaces, such that for each pair of adjacent first and second structures of the plurality of structures: The first side surface of the first structure faces the second side surface of the second structure, and the first side surface and the second side surface are connected to each other through the connecting surface portion of the structured main surface; A first layer having the same first composition is coated on at least a majority of each of the first side surface and the second side surface; and A second layer of the same second composition, different from the first composition, is applied to at least a majority of the connecting surface portion and to adjacent portions of the first side surface and the second side surface.

10. The light-controlling film of claim 9, wherein for each pair of adjacent first and second structures in the plurality of structures, no portion of the first layer is disposed between the second layer and the structured main surface.

11. The light-controlling film of claim 9, wherein for each pair of adjacent first and second structures in the plurality of structures, the second layer coats a portion of each of the first side surface and the second side surface.

12. A light-controlling film, the light-controlling film comprising a structured main surface extending substantially continuously over the entire length and width of the light-controlling film and comprising a plurality of structures, each of the structures comprising a top surface extending between opposing side surfaces of the structure and engaging the opposing side surfaces of the structure, such that for each of the plurality of structures: A first layer having the same first composition is disposed on at least a majority of each of the first side surface and the second side surface and extends together with said at least a majority of each of the first side surface and the second side surface; and A second layer of the same second composition, different from the first composition, is coated on at least most of the top surface, and on the portion of each of the first and second side surfaces adjacent to the top surface.

13. The light-controlling film of claim 12, wherein for each of the plurality of structures, the second layer is a release layer, and for each of the first side surface and the second side surface, the first layer is optically absorptive and substantially permanently attached to the side surface.

14. The light-controlling film of claim 13, wherein for at least one side surface of each of at least some of the plurality of structures, the first layer at least partially covers the release layer.

15. The light control film of claim 12, further comprising a third layer disposed above the structured main surface and substantially filling the space between adjacent structures of the plurality of structures, wherein for each of the structures, no portion of the third layer is disposed between the structure and either the first layer or the second layer.

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