WO2025003854A1

WO2025003854A1 - Light control film

Info

Publication number: WO2025003854A1
Application number: PCT/IB2024/056103
Authority: WO
Inventors: Henrik B. VAN LENGERICH; Matthew S. Stay; Matthew R.D. SMITH; John-Paul R. HEINZEN; Daniel J. Schmidt; Kevin W. GOTRIK; Caleb T. NELSON; Ellison G. KAWAKAMI; Kayla C. PICHA; Raymond J. Kenney; David J. TARNOWSKI; Kui Chen-Ho; Benjamin R. COONCE; Brylee David B. TIU; Kristin L. Thunhorst
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2023-06-30
Filing date: 2024-06-21
Publication date: 2025-01-02
Anticipated expiration: 2025-12-30

Abstract

A light control film includes an optical film shaped to define a plurality of substantially linear alternating ridges and grooves extending along substantially a same first direction and arranged along an orthogonal second direction. Each of the grooves includes first and second layers disposed therein and stacked along a thickness direction of the light control film. The second layer is disposed between the first layer and a bottom of the groove. For each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, an interface layer that is substantially coextensive along the first direction with the ridge 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.

Description

LIGHT CONTROL FILM

TECHNICAL FIELD

The present description generally relates to light control films.

BACKGROUND

A light control film generally controls the angular distribution of light transmitted through the light control film.

SUMMARY

In some aspects, the present description provides a light control film including an optical film shaped to define a plurality of substantially linear alternating ridges and grooves extending along substantially a same first direction and arranged along an orthogonal second direction. Each of the grooves includes first and second layers disposed therein and stacked along a thickness direction of the light control film. Each of the first and second layers has a maximum thickness of greater than about 0.01 microns. The second layer is disposed between the first layer and a bottom of the groove. For each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, an interface layer that is substantially coextensive along the first direction with the ridge 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 of greater than about 0.01 microns and less than about 10 microns.

In some aspects, the present description provides a light control film having a structured major surface extending continuously across substantially an entire length and an entire width of the light control film and including a plurality of structures. Each of the structures has a top surface extending between and joining opposing side surfaces. The light control film is such that for each pair of adjacent first and second structures in the plurality of structures: a first side surface of the first structure faces a second side surface of the second structure, where the first and second side surfaces are connected to each other 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 and second side surfaces; and a same second layer having a same second composition different than 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 aspects, the present description provides a light control film having a structured major surface extending continuously across substantially an entire length and an entire width of the light control film and comprising a plurality of structures. Each of the structures having a top surface extending between and joining opposing side surfaces of the structure. The light control film is such that for each structure in 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 than 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.

In some aspects, the present description provides a method of making a light control film. The method includes: depositing an optically absorptive layer onto a first structured major surface of a first film such that the optically absorptive layer substantially conforms to the first structured major surface, where the first structured major surface comprises a plurality of first structures arranged along a first direction and defining a plurality of first channels extending along an orthogonal second direction, and where each first channel is disposed between adjacent first structures and has an open top opposite a bottom of the first channel; removing the optically absorptive layer from a top portion of each first structure of the plurality of first structures, where the top portions of the first structures are adjacent to the open tops of the first channels; for each first channel in the plurality of first channels, disposing a release layer on the optically absorptive layer along the bottom of the first channel and along at least a portion of sidewalls of the first structures adjacent the first channel; after the removing and disposing steps, substantially filling each first channel in 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, where each second structure extends from the land portion to a top portion of the second structure, and where the top portion extends between and joins opposing sidewalls of the second structure; separating the first and second films such that the second film includes the optically absorptive layer disposed on the sidewalls and top portions of the second structures; and for each second structure in the plurality of second structures, removing the optically absorptive layer from at least the top portion of the second structure to expose the release layer.

In some aspects, the present description provides a method of making a light control film. The method includes: for a first film comprising a first structured major surface including a plurality of first structures arranged along a first direction and defining a plurality of first channels extending along an orthogonal second direction, where each first channel is disposed between adjacent first structures and has an open top opposite a bottom of the first channel, and where each of the first structures has a top surface extending between and joining opposing side surfaces of the first structure, coating a release layer onto the top surfaces of the first structures; substantially filling each first channel in the plurality of first channels with a resin; solidifying the resin to form a second film comprising a land portion and a second structured major surface comprising a plurality of second structures, where each second structure extends from the land portion to a top surface of the second structure, and where the top surface extends between and joins opposing sidewalls and of the second structure; separating the first and second films such that the second film comprises the release layer disposed on the land portion; depositing an optically absorptive layer onto the second structured major surface such that the optically absorptive layer substantially conforms to the second structured major surface; and removing the optically absorptive layer from the top surfaces of the second structures and from the release layer. These and other aspects will be apparent from the following detailed description. In no event, however, should this brief summary be construed to limit the claimable subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 are schematic cross-sectional views of light control fdms, according to some embodiments.

FIG. 3 is a schematic cross-sectional view of an optical fdm 10, according to some embodiments.

FIGS. 4-5 are schematic cross-section views of portions of optical films, according so some embodiments.

FIGS. 6-7 are schematic cross-sectional views of light control films where a second layer covers portions of sidewalls of ridges, according to some embodiments.

FIGS. 8-9 are schematic cross-sectional views of light control films where a second layer covers tops and portions of sidewalls of ridges, according to some embodiments.

FIG. 10 is a schematic cross-sectional view of a light control film disposed adjacent a light source, according to some embodiments.

FIG. 11 schematically illustrates initial steps of processes for making a light control film, according to some embodiments.

FIGS. 12-13 schematically illustrates steps of a process for making a light control film, according to some embodiments.

FIG. 14 schematically illustrates a process for making a light control film, according to some embodiments.

FIGS. 15-16 are scanning electron microscope (SEM) images of exemplary light control films, according to some embodiments.

DETAILED DESCRIPTION

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

A light control film can include alternating light absorbing 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. Pat. Appl. 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 horizontal surfaces which are desired to be transmissive. According to some embodiments of the present description, methods of forming light control fdms are provided that utilize light absorbing regions that may be formed via LbL self-assembly, for example, without the need for a reactive ion etching step, for example, or other vacuum processing steps. The described methods can be more cost-effective, for example, than conventional methods. The resulting light control fdm may include a release layer that may be embedded in the light control fdm, according to some embodiments.

FIGS. 1-2 are schematic cross-sectional views of light control fdms, according to some embodiments. In some embodiments, the light control fdm 300, 400 (or other light control fdms described elsewhere herein) includes an optical fdm 10 shaped to define a plurality of substantially linear alternating ridges 20 and grooves 30 extending along substantially a same first direction (y-direction) and arranged along an orthogonal second direction (x-direction), where each of the grooves 30 includes a first layer 31 disposed therein. Alternatively, or in addition, in some embodiments, the light control fdm 300, 400 can be described as including an optical fdm 10’ shaped to define a plurality of substantially linear alternating ridges 20’ and grooves 30’ extending along substantially a same first direction (y-direction) and arranged along an orthogonal second direction (x-direction), where each of the grooves includes a first layer 31 ’ disposed therein. In some embodiments, each of the grooves 30 of the optical fdm 10 includes a second layer 32 disposed therein (e.g., on at least a bottom 33 of the groove and/or between the bottom 33 and the first layer 31) where the first and second layer can be stacked along a thickness direction (z-direction) of the light control fdm and the second layer can be disposed between the first layer and a bottom 33 of the groove. Alternatively, or in addition, in some embodiments, the light control fdm 300, 400 can be described as including a second layer 32 disposed on at least a top 21 ’ of each of the ridges 20’ of the optical fdm 10’. In some embodiments, as schematically illustrated in FIG. 2, each of the grooves 30’ of the optical fdm 10’ includes a second layer 32’ disposed therein (e.g., on at least a bottom 33 ’ of the groove and/or between the bottom 33 ’ and the first layer 31’) where the first and second layer can be stacked along a thickness direction (z-direction) of the light control fdm and the second layer can be disposed between the first layer and a bottom 33’ of the groove. Alternatively, or in addition, in some embodiments, the light control fdm 400 can be described as including a second layer 32’ disposed on at least a top 21 of each of the ridges 20 of the optical fdm 10.

In some embodiments, the second layer 32 and/or 32’ may also be disposed on portions of opposing sides of the ridges of the optical fdm 10 and/or 10’, as described further elsewhere herein.

The plurality of substantially linear alternating ridges 20 and grooves 30 extending along substantially a same first direction can extend nominally linearly along the first direction or can extend linearly along the first direction up to deviations along the second direction less than about 20, 10, or 5% of an average spacing of the ridges along the second direction, for example.

In some embodiments, the optical fdm 10 is shaped to further define a land portion 11 extending continuously across substantially a length (y-direction) and a width (x-direction) of the optical fdm 10 and joining the ridges 20 and the grooves 30. In some embodiments, the first layers 31 are joined by a land portion 11 ’ that has a same composition as the first layers, extends continuously across substantially a length (y-direction) and a width (x-direction) of the optical film, and covers tops of the ridges. In some embodiments, the optical film 10’ is shaped to further define a land portion 11’ extending continuously across substantially a length (y-direction) and a width (x-direction) of the optical film 10’ and joining the ridges 20’ and the grooves 30’. In some embodiments, the land portion 11 and/or 11’ extends across greater than 60, 70, 80, 90, or 95 percent of each of the length and width of the optical film. In some embodiments, the land portion 11 or 11’ may be omitted. In some embodiments, the grooves 30 (or 30’) have a bottom portion 35 (or 35’) comprising the bottom 33 (or 33’) of the groove. The bottom portion 35, 35’ can be or include a connecting surface portion extending between and connecting side surfaces of adjacent ridges. In some embodiments, the land portion 11 and/or 11’ has an average thickness (see, e.g., t3 depicted in FIG. 3) of greater than about 0.2, 0.5, 1, 2, 5, or 10 microns. In some embodiments, the average thickness of the land portion is less than about 50, 45, 40, 35, 30, 25, or 20 microns.

In some embodiments, the optical film 10 is disposed on a substrate 60. In some embodiments, the optical film 10’ is disposed on a substrate 60’. In some embodiments, at least one of the substrates 60, 60’ is omitted. In some embodiments, at least one the substrates 60, 60’ is or includes a glass layer. In some embodiments, at least one the substrates 60, 60’ is or includes a polymeric film. Useful polymers for the polymeric film (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 acids, polyolefin-based material such as cast or orientated films of polyethylene, polypropylene, and polycyclo- olefins, polyimides, or combinations of these materials. For example, the polymeric film can be a polyethylene terephthalate (PET) film, a polypropylene film, or a polycarbonate film, for example. The film may 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 U.S. Pat. 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.), for example. The multilayer optical film may be included to provide a better defined effective viewing angle cut-off, for example, as described in U.S. Pat. 8,503,122 (Eiu et al.), for example.

In some embodiments, the optical film 10 has a structured major surface 15. In some embodiments, the optical film 10’ has a structured major surface 15’. In some embodiments, one of the optical films 10, 10’ is formed on a substrate 60, 60’ using a cast and solidify (e.g., cure) process and the other of the optical films 10, 10’ is formed by backfilling the resulting grooves with a resin (e.g., a polymerizable material or a molten polymer) and solidifying (e.g., via curing or cooling) the resin to provide the film. The cast and solidify process can result in a land 11 or 11’, and the backfilling and solidifying can optionally also result in a land 11 ’ or 11. The cast and solidify process can be a cast and cure process using microreplication from a tool by casting and curing (e.g., by applying actinic radiation such as ultraviolet (UV) radiation) a polymerizable resin composition in contact with a structured surface of the tool. Such cast and cure methods are described in U.S. Pat. Nos. 5,175,030 (Lu et al.) and 5,183,597 (Lu) and in U.S. Pat. Appl. Pub. No. 2012/0064296 (Walker, JR. et al.), for example. Further details on useful processes to make the light control fdms are described further elsewhere herein. In some embodiments, the optical film 10’ is omitted. In some embodiments, the first layer 31 is air or mostly air. In other embodiments, the optical film 10’ is a polymeric film and the optical film 10 is omitted. In some embodiments, the first layer 31 ’ is air or mostly air. For example, the backfilling and curing step can optionally be omitted.

In some embodiments, a layer 40 is disposed between each pair of adjacent ridges 20 and 20’. The layer 40 can be an optically absorptive layer. A thickness t of the layers 40 is schematically illustrated in FIGS. 1-2. The thickness t can schematically represent a maximum thickness of a layer 40 or an average thickness of the plurality of layers 40. The layers 40 have an average height hl in a thickness direction of the light control film 300, 400 that is orthogonal to each of the first and second directions. In some embodiments, the layers 40 have an average thickness t an average height hl along the thickness direction (z-direction) where hl/t > 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, or 200. The aspect ratio hl/t can be up to 10000 or 5,000 or 1000, for example. In some embodiments, the (interface) layer 40 has a maximum thickness of greater than about 0.01, 0.025, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, or 0.6 microns. In some embodiments, the maximum thickness is less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1.5 microns. Such high aspect ratio layers may be formed via LbL self-assembly, for example, as described further elsewhere herein.

In some embodiments, the ridges 20 have an average height h2 in the thickness direction. In some embodiments, the ridges 20’ have an average height h2’ in the thickness direction. In some embodiments, a difference between h2 and h2’ is a thickness of the layers 32. In some embodiments, hl is greater than about 0.5, 0.6, 0.7, 0.8, or 0.9 times h2. In some embodiments, hl is greater than about 0.5, 0.6, 0.7, 0.8, 0.9, or 0.95 times h2’. In some embodiments, h2 and h2’ are each less than about 1 mm. In some embodiments, hl is greater than about 1 micron and less than each of h2 and h2’.

The layer 40 can be an interface layer between the ridges and the first layer. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, an interface layer 40 that is substantially coextensive along the first direction with the ridge 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. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, the second layer directly contacts the ridge adjacent the bottom of the groove. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, at least 50, 60, 70, 80, 90, 95, 96, 97, 98, or 99 percent by area of the interface layer 40 is not disposed between the ridge and the second layer. The area here refers to the area of a major surface of the layer 40. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, no portion of the interface layer 40 is disposed between the ridge and the second layer. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, at least 60, 70, 80, 90, 95, 96, 97, 98, or 99 percent by area of the interface layer is disposed directly on the ridge.

An element (e.g., interface layer 40) can be described as substantially coextensive with another element (e.g., a ridge) along a direction if at least about 60% of the length 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 an element is substantially coextensive with another element along a direction, at least about 70, 80, or 90% of the length 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 ridge and groove in the plurality of alternating ridges and grooves, at least 70, 80, or 90% of a length of the interface layer 40 along the first direction is coextensive with at least 70, 80, or 90% of a length of the ridge along the first direction.

In some embodiments, the second layers 32 are disposed at, and make physical contact with, bottoms 33 of the grooves 30. In some embodiments, the second layers 32 make physical contact with sides 13, 14 of the ridges adjacent the bottoms 33 of the grooves 30. In some embodiments, the second layers 32 are disposed at, and make physical contact with, tops 21’ of the ridges 20’. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, no portion of the interface layer 40 is disposed on the bottom 33 (or 33’) of the groove and no portion of the interface layer 40 is disposed on a top 21 (or 21’) of the ridge. In some embodiments, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, each of the bottom 33 (or 33’) of the groove and a top 21 (or 21 ’) of the ridge is substantially free of any light absorbing layer. For example, the bottoms and tops can be completely free of any light absorbing layer or can include a sufficiently small amount of light absorbing material that the on-axis transmission of the light control film is not reduced by more than 10 (or 5, or 3) percent compared to the same light control film but without any light absorbing layer on the bottoms and tops.

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’ is included (see, e.g., FIG. 2) and covers a length L2’ of the sidewall. In some embodiments, Ll/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, Ll/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/LF, or L27LF 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, L2 can be relatively small (e.g., L2/Lt < 0.1) when there is little wet out of the layer 32 along the sidewalls (e.g., when formed using the methods of FIGS. 11-13) or can be relatively large (e.g., L2/Lt > 0. 1) when there is more wet out of the layer 32 along the sidewalls (e.g., when formed using the method of FIG. 14).

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

In some embodiments, each of the first and second layers has a maximum thickness tl, t2 of greater than about 0.01, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5, 1, 2, 3, 4, or 5 microns. In some embodiments, the maximum thickness tl of the first layer is greater than the maximum thickness t2 of the second layer by at least a factor of 1.5, 2, 5, 10, 20, 50, 100, 150, or 200. In some embodiments, the maximum thickness tl is less than about 1 mm. In embodiments where the first layer 31 is air, the maximum thickness of the first layer should be understood to be the maximum thickness between the tops 21 of the ridges 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 should be understood to be the maximum thickness between the tops 21’ of the ridges 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 layers are less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 microns thick. In some embodiments, the first layers are greater than about 10, 20, 30, 40, 50, 60, 70, 80, or 90 microns thick.

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 layers have substantially a same first composition and the second layers have substantially a same second composition different from the first composition. In some embodiments, the first composition comprises an acrylate. In some embodiments, the optical film has a unitary construction having a substantially uniform third composition. In some embodiments, the third composition comprises 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 layers are release layers. In some embodiments, the light control film includes a plurality of discrete spaced apart release layers (32 and/or 32’ in each of the grooves 30 and/or 30’) embedded therein. In some embodiments, the second composition comprises one or more of a polyvinyl alcohol, a silicone, a wax, a paraffin, a hydrophobic material, a fluorinated material, ethylene vinyl acetate, polyvinyl butyral, polylactic acid, and a 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. Of these, silicone poly(meth)acrylates may be preferred because the likelihood of unbound silicone (meth)acrylate after curing is generally reduced. Exemplary silicone (meth)acrylates include EBECRYL 350 silicone diacrylate and EBECRYL 1360 silicone hexaacrylate from Allnex, CN9800 aliphatic silicone acrylate and CN990 siliconized urethane acrylate compound from Sartomer Co., and TEGO RC 702, TEGO RAD 2100, TEGO RAD 2250, and TEGO RAD 2500 silicone polyether acrylate from Evonik Industries, Parsippany, New Jersey.

In some embodiments, for at least one same visible wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the first and second layers have indices of refraction that are different by at least about 0.05, or 0.1, or 0.15, or 0.2, or 0.25, or 0.3. In some embodiments, the indices of refraction are different by less than about 2, 1.5, or 1. In some embodiments, the first layers have an index of refraction 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 a visible wavelength range extending from about 420 nm to about 680 nm. In some embodiments, the first layers comprise mostly air. In some embodiments, the first layers comprise a nanovoided ultra-low index material such as those described in in U.S. Pat. Appl. Publ. Nos. 2012/0038990 (Hao et al.), 2013/0011608 (Wolk et al.) and 2013/0235614 (Wolk et al.), for example.

The layers 40 may be formed via layer-by-layer (LbL) coating, chemical vapor deposition (CVD), sputtering, reactive sputtering, or atomic layer deposition (ALD), for example. In some embodiments, the layers 40 are formed via LbL self-assembly as described in U.S. Pat. Appl. Nos. 2020/0400865 (Schmidt et al.); 2021/0333624 (Schmidt et al.); 2022/0019007 (Schmidt et al.); and 2023/00289558 (Liu et al.), for example. 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 comprises organic and/or inorganic polyions and counterions. For example, in some embodiments, the plurality of polyelectrolyte layers comprises organic polymeric polyions and counterions. In some embodiments, the plurality of polyelectrolyte layers comprises a light absorbing material. In some embodiments, the (interface) layer 40 includes a light absorbing core layer disposed between first and second cladding layers (e.g., as schematically illustrated in FIG. 5 for layers 40’). Utilizing suitable core and cladding layers can result in improved axial brightness of light passing through the film with the brightness being more uniform within the viewing angle and with the viewing cutoff angle being sharpened as described in U.S. Pat. Appl. Nos. 2021/0333624 (Schmidt et al.) and 2023/00289558 (Liu et al.), for example. In some embodiments, each of the core and first and second cladding layers comprises a plurality of polyelectrolyte layers.

LbL self-assembly is commonly used to assemble films or coatings of oppositely charged polyelectrolytes electrostatically, but other functionalities such as hydrogen bond donor/acceptors, metal ions/ligands, and covalent bonding moieties can be the driving force for film assembly. Some examples of suitable processes include those described in U.S. Pat. Nos. 8,234,998 (Krogman et al.,) and 8,313,798 (Nogueira et al.); in U.S. Pat. Appl. Pub. Nos. 2011/0064936 (Hammond-Cunningham et al.); and 2020/0400865 (Schmidt et al.). Layer-by layer dip coating can be conducted using a StratoSequence VI (nanoStrata Inc., Tallahassee, FL) dip coating robot, for example. 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 polyelectrolyte stack including an organic (e.g., polymeric) and/or inorganic polyion (e.g., cation) and counterion (e.g., anion). At least a portion of the cation layers, anion layers, or a combination thereof can include a light absorbing material (e.g., pigment) ionically bonded to the polyelectrolyte. A 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 available from vendors such as Cabot Corporation (Boston, Massachusetts), for example under the tradenames CAB-O-JET 200, 300, 352K, and 400 and Orient Corporation of America (Cranford, New Jersey), for example under the tradenames BONJET CW-1, CW-2, and CW-3.

Suitable polymers that include a plurality of positively charged ionic (or ionizable) groups (i.e., polycationic polyelectrolyte polymers) can be derived from these monomers, for example:

• Primary amino-containing monomers and their salts (e.g., hydrochloride salts): vinyl amine, allyl amine, aminoalkyl(meth)acrylamide, aminoalkyl (meth)acrylate, 2-N-morpholinoalkyl (meth)acrylate;

• Secondary amino-containing monomers and their salts (e.g., hydrochloride salts): alkylaminoalkylene (meth)acrylates such as, for example, 2-(methylamino)ethyl (meth)acylate;

• Tertiary amino-containing monomers and their salts (e.g., hydrochloride salts): various N,N- dialkylaminoalkyl (meth)acrylates and N,N-dialkylaminoalkyl (meth)acrylamides such as N,N- dimethyl aminoethyl (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 methacrylate, (tert-Butylamino)alkyl methacrylamide; and

• Quaternary amino-containing monomers: methacryloylaminopropyl trimethylammonium chloride, diallyldimethylammonium chloride, 2-acryloxyalkyltrimethylammonium chloride.

Some of the more common polycationic polymers used for layer-by-layer coating are: linear and branched poly(ethylenimine) (PEI), poly(allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltrimethylamine), polydiallyldimethylammonium chloride (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamino)propyl- trimethylammonium chloride, and combinations thereof including copolymers thereof.

Suitable polycations may also include polymer latexes, dispersions, or emulsions with positively charged functional groups on the surface. Examples include Sancure 20051 and Sancure 20072 cationic polyurethane dispersions available from Lubrizol Corporation (Wickliffe, Ohio). Suitable poly cations may also include inorganic nanoparticles (for example, aluminum oxide, zirconium oxide, titanium dioxide) suitably below their native isoelectric point, or alternatively surface-modified with positively charged functional groups.

Suitable polymers that include negatively charged ionic (or ionizable) groups (i.e., polyanionic polyelectrolyte polymers) can be derived from these monomers (and salts thereof), for example: Acid monomers: (meth)acrylic acid, B-carboxyethyl (meth)acylate, 2-(meth)acrylolyoxyethyl phthalic acid, 2- (meth)acryloyloxy succinic acid, vinyl phosphonic acid, vinyl sulfonic acid, styrene sulfonic acid, and 2- acrylamido-2 -methylpropane sulfonic acid, (meth)acrylate salts (i.e., zinc acrylate, zirconium acrylate, etc.), carboxy ethyl (meth)acrylate salts (i.e., zirconium carboxyethyl acrylate), 2-sulfoalkyl (meth)acrylate, phosphonoalkyl (meth)acrylate, phosphoric acid 2-hydroxyethyl methacrylate ester.

Some of the more common polyanionic polymers used 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, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers such as NAFION, poly(vinylphosphoric acid), poly(vinylphosphonic acid), and combinations thereof including copolymers thereof.

Suitable polyanions may also include polymer latexes, dispersions, or emulsions with negatively charged functional groups on the surface. Such polymers are available, for example, under the JONCRYL tradename (BASF, Florham Park, New Jersey), CARBOSET tradename (Lubrizol Corporation, Wickliffe, Ohio), and NEOCRYL tradename (DSM Coating Resins, Wilmington, Massachusetts). Suitable anions may also include inorganic nanoparticles (for example, silicon oxide, aluminum oxide, zirconium oxide, titanium dioxide, nano-clay) suitably above their native isoelectric point, or alternatively surface-modified with negatively charged functional groups.

The thickness of a bilayer and the number of bilayers in the (interface) layer 40 can be selected to achieve the desired optical properties (e.g., light absorption in the case of an optically absorptive core of the interface layer 40, or reduced reflection between the sidewall and the optically absorptive layer in the case of a cladding layer of the interface layer 40). In some embodiments, the thickness of a bilayer and/or the number of bilayers can be selected to achieve the desired optical properties using the minimum total thickness of self-assembled layers and/or the minimum number of layer-by-layer deposition steps. The thickness of each bilayer typically ranges from about 5 nm to 350 nm. The number of bilayers in a layer 40 is typically at least 5, 6, 7, 8, 9, or 10. In some embodiments, the number of bilayers in a layer 40 is no greater than 150 or 100. It should be appreciated that individual bilayers in the final article may not be distinguishable from each other 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 are selected such that the total thickness of the layer 40 (e.g., the total thickness of any cladding layer and the optically absorptive core layer) is less than about 2 micrometers, or 1.75 micrometers, or 1.50 micrometers, or 1.25 micrometers, or 1.00 micrometers, or 0.75 micrometers, or 0.50 micrometers, or 0.25 micrometers, for example. FIG. 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 optical film that is substantially orthogonal to the light control 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 and 14 (e.g., any radius of curvature of the side 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 makes an angle 01 of greater than about 80, or 82, or 84, or 85, or 86, or 87, or 88, or 89, or 89.5 degrees with a substantially planar major surface 12 of the light control film. In some embodiments, in a planar cross-section (xz-plane) of the optical film that is substantially orthogonal to the light control film and the first direction, each of the ridges has maximum width Wmax that is within 20%, 15%, 10%, or 5% of a minimum width Wmin of the ridge. In some embodiments, in a planar cross-section (xz-plane) of the optical film that is substantially orthogonal to the light control film and the first direction, each of the ridges has 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 some embodiments, each of Hmax, Wmax, and Wmin is in a range of about 0.05 microns to about 1 mm, or about 0.1 microns to about 0.75 mm, or about 0.2 microns to about 0.5 mm. In some embodiments, in a planar cross-section (xz-plane) of the optical film that is substantially orthogonal to the light control film and the first direction, each of the ridges has a substantially polygonal shape. A substantially polygonal shape appears generally polygonal but may have rounded comers or slightly rounded sides, for example, that have a radius of curvature small (e.g., less than about 10%) compared to other dimensions (e.g., Wmin) of the ridges. For example, the ridges of FIGS. 15-16 are substantially polygonal. In some embodiments, the polygonal shape is trapezoidal or rectangular.

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

The optical film 10’ may, in some embodiments, have a geometry similar (e.g., a substantially polygonal shape) to that of optical film 10 with any one or more of Wmin, Wmax, Hmax, 01, t3 in the same range as described for optical film 10.

FIG. 4 is a schematic cross-section view of a portion of an optical film (e.g., corresponding to optical film 10) having a ridge with curved sidewalls, according so some embodiments. In some embodiments, in a planar cross-section (xz-plane) of the optical film that is substantially orthogonal to the light control film and the first direction, each of the ridges has opposing first 13 and second 14 sides, where at least one of the first and second sides is curved. In some embodiments, the at least one of the first and second sides that is curved makes a maximum angle 01’ of greater than about 80, 82, 84, 85, 86, 87, 88, 89, or 89.5 degrees with a substantially planar major surface 12 of the light control film. Each of the sidewalls 13, 14 of the ridge 20 are curved outward in the illustrated embodiment. The corresponding sidewalls of the ridges of the optical film 10’ may be curved inward. Alternatively, the sidewalls of the ridges of the optical film 10 may be curved inward and the sidewalls of the ridges of the optical film 10’ may be curved outward. In some embodiments, only one of the sidewalls of the ridge 20 or 20’ is curved or one sidewall is curved outwardly and the other sidewall is curved inwardly.

FIG. 5 is a schematic cross-section view of a portion of an optical film (e.g., corresponding to optical film 10) having a groove 30 with a curved bottom, according so some embodiments. The illustrated portion can repeat along the second direction (x-direction), for example. In some embodiments, in a planar cross-section (xz-plane) of the light control film that is substantially orthogonal to the light control film and the first direction, each of the grooves comprises a bottom portion 35 comprising the bottom 33 of the groove and opposing substantially straight sides 34 extending upwardly from opposite ends 35a of the bottom portion of the groove, where the second layer 32 conformally coats at least the bottom portion 35 of the groove (so that the 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 grooves is curved.

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

In some embodiments, a minimum separation t3 between the bottoms 33 of the grooves and a closest substantially planar major surface 12 of the light control film that extends continuously across substantially an entire width (x-direction) and an entire length (y-direction) of the light control film is greater than about 0.2, 0.5, 1, 2, 5, or 10 microns. In some embodiments, the minimum separation t3 is less than about 50, 45, 40, 35, 30, 25, or 20 microns.

In some embodiments, each of the interface layers 40’ (e.g., corresponding to layers 40) includes a light absorbing core layer disposed between first and second cladding layers as schematically illustrated in FIG. 5 and as described further elsewhere herein.

FIGS. 6-7 are schematic cross-sectional views of light control films where a second layer 32 covers portions of sidewalls of the ridges 20, according to some embodiments. In some embodiments, as schematically illustrated in FIG. 6 for light control film 500, for each sidewall, no portion of a layer 40 is disposed between layer 32 and the sidewall. In some embodiments, as schematically illustrated in FIG. 7 for light control film 700, for at least some of the sidewalls, a portion of the layer 40 is disposed between layer 32 and the sidewall. In some embodiments, in a planar cross-section (xz-plane) of the light control film that is substantially orthogonal to the light control film and the first direction, and for each of at least two of the grooves of the optical film, the groove comprises opposing sides 34 extending upwardly from opposite ends of the bottom of the groove, where the second layer 32 has a thicker middle portion 32a disposed between opposing thinner end portions 32b, where the thicker middle portion is disposed at the bottom 33 of the groove, and where the opposing thinner end portions are disposed on the opposing side portions of the groove.

FIGS. 8-9 are schematic cross-sectional views of light control films where a second layer 32 covers tops and portions of sidewalls of the ridges 20’, according to some embodiments. The light control film 700, 800 includes an optical film 10’ having a structured major surface 15’ defining a plurality of alternating ridges 20’ and valleys 30’. A layer 32 is disposed on tops 21 and adjacent portions of sidewalls 13’ and 14’ of the ridges 20’. The ridges 20’ with the layer 32 defines a structure 120 which may have a substantially polygonal (e.g., trapezoidal or rectangular) shape. The layer 32 may be sufficiently thin on the sidewalls 13’, 14’ that the ridges 20’ may also have a substantially trapezoidal or rectangular shape, for example. In some embodiment, no portion of the layer 32 is disposed between the layer 40 and the ridge 20’ as schematically illustrated in FIG. 8. In some embodiments, there can be a gap between the layer 32 and the layer 40 (see, e.g., FIG. 6). In some embodiments, there is substantially no gap between the layer 32 and the layer 40. In some embodiment, a portion of the layer 32 is disposed between the layer 40 and the ridge 20’ as schematically illustrated in FIG. 9, for example.

The light control films may be described in terms of ridges and grooves of an optical film. Alternatively, or in addition, the light control films may be described in terms of structures of a structured major surface. In some cases, a same layer may be referred to differently (e.g., interface layer vs. first layer) for the different descriptions.

In some embodiments, a light control film (300, 400, 500, 600, 700, 800 or other light control films described elsewhere herein) includes a structured major surface 15 (or 15’) extending continuously across substantially an entire length (y-axis) and an entire width (x-axis) of the light control film and including a plurality of structures 20 (or 20’), where each of the structures includes a top surface 21 (or 21’) extending between and joining 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 in 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 connected to each other by a connecting surface portion (see, e.g., portion 35 depicted in FIG. 5) 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 than 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 in 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 than 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.

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

In some embodiments, for each pair of adjacent first and second structures in the plurality of structures, no more than 80, 70, 60, 50, 40, 30, 20, 10, 5, 4, 3, 2, or 1 percent by area of the first layers 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 layers 40 is disposed between the second layer and the structured major surface. For example, for light control film 500 schematically illustrated in FIG. 6, no portion of the first layers 40 is disposed between the second layer 32 and the structured major surface 15, while for light control film 600 schematically illustrated in FIG. 7, some portion of the first layers 40 is disposed between the second layer 32 and the structured major surface 15. Light control films made according to the process schematically illustrated in FIGS. 11-12, for example, may result in little or no portion of the first layers 40 being disposed between the second layer 32 and the structured major surface 15, while light control films made according to the process schematically illustrated in FIG. 14, for example, may result in a substantial portion of the first layers 40 being disposed between the second layer 32 and the structured major surface 15.

In some embodiments, for each pair of adjacent first and second structures in 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 in the plurality of structures, the second layer 32 covers (e.g., coats) portions of each of the first and second side surfaces. In some embodiments, for each pair of adjacent first and second structures in 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% by area of each of the first and second side surfaces. In some embodiments, for each pair of adjacent first and second structures in 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.

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) that is substantially orthogonal to the light control film and the length direction, for each side surface of each structure in 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 L27Lt) is greater than 0.05 (or in a range described elsewhere herein) and Ll/Lt > 0.5 (or in a range described elsewhere herein). In some embodiments, a 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.

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

In some embodiments, the structures in the plurality of structures are arranged as a regular array of structures. In some embodiments, the structures in 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 the length of the light control film. In some embodiments, the first layer 40 is substantially coextensive along the first direction with each of the first and second side surfaces. In some embodiments, the second layer is substantially coextensive along the first direction with the connecting surface portion 35.

In some embodiments, the first layers 40 have an average thickness t and an average height hl along a thickness direction of the light control film orthogonal to each of mutually orthogonal length and width directions of the light control film, where hl/t > 10 (or in a range described elsewhere herein).

In some embodiments, the first layers 40 are optically absorptive. In some embodiments, the first layers 40 have an optical density of 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 transmission through the layer, where the transmission should be understood to be the average transmission for normally incident light in a wavelength range of about 420 to 680 nm, unless indicated differently. In some embodiments, the first layers 40 are optically absorptive and the second layers 32 (or 32’) are release layers. In some embodiments, for each structure in 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, but not a top portion, of the side surface, where the top portion is disposed between the top surface and the bottom portion. In some embodiments, for each structure in the plurality of structures and each of the first and second side surfaces of the structure, a bottom portion, but not a top portion, of the first layer is substantially permanently bonded to the side surface, where the top portion is disposed between the top surface and the bottom portion. In some embodiments, for each structure in 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 structures in the plurality of structures, the first layer at least partially covers the release layer. For example, for the light control film 800 schematically illustrated in FIG. 9, the layers 40 can be permanently attached to the bottom portion of the side surfaces of the structures 20 but an upper portion of the layers 40 may not be permanently atached to the side surface when the layer 32 is a release layer. A layer is substantially permanently bonded or attached to an element when the layer cannot be removed from the element without significant damage (e.g., breaking or cracking) to at least one of the layer or element. Each layer 40 can be substantially permanently directly atached to a side surface of a structure in the plurality of structures.

In some embodiments, a third layer 31 (or 31’) is disposed over the structured major surface 15 (or 15’) and substantially fills spaces between adjacent structures of the plurality of structures. In some embodiments, for each of the structures, no portion of the third layer is disposed between the structure and either of the first or second layers. The third layer can be an air layer or a polymeric layer, for example. In some embodiments, air substantially fills spaces 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 (e.g., nominally conforming or conforming up to variations less than 10% of Wmin, for example) to the first structured major surface (e.g., 15’) and an opposite substantially planar major surface (e.g., surface 12’ schematically illustrated in FIG. 2). 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, 70, 60, 50, 40, 30, 20, 10, 5, 4, 3, 2, or 1 percent by area of the first layers 40 is disposed between the second layer 32 (or 32’) and the second structured major surface. In some embodiments, no portion of the first layers is disposed between the second layer and the second structured major surface.

FIG. 10 is a schematic cross-sectional view of a light control film 900 disposed adjacent a light source 50, according to some embodiments. The light control film 900 can correspond to any light control film of the present description. In some embodiments, the (interface or first) layer 40 is substantially light absorbing having an optical density of greater than about 0.1 (or in a range described elsewhere herein). When the layers 40 are light absorbing, the light control film can be effective at limiting the angular range of light transmited 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 transmited light 52 having an intensity profile having a full width at half maximum (FWHM) of less than about 120, 110, 100, 90, 80, 75, 70, 65, 60, 55, 50, or 45 degrees in a planar cross-section (xz-plane) of the intensity profile that is substantially orthogonal to the light control film and the first direction (y-direction). In some embodiments, the (interface or first) layer 40 has a high aspect ratio (e.g., hl/t > 10 or in a range described elsewhere herein), so that the light control film substantially transmits on-axis visible light. In some embodiments, the light control film 900 has an average on-axis transmission of at least about 65, 70, 75, 80, or 85 percent in a wavelength range of about 420 nm to about 680 nm.

FIG. 11 schematically illustrates initial steps of processes for making a light control film, according to some embodiments. FIG. 12 schematically illustrates steps of a process for making a light control film such as light control film 300 or 500, for example, according to some embodiments. FIG. 13 schematically illustrates steps of a process for making a light control film such as light control film 400, for example, according to some embodiments.

In some embodiments, a method of making a light control film includes the following steps. Step 1 ((a) to (b) in FIG. 11): for a first film 301 having a first structured major surface including 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), where each first channel is disposed between adjacent first structures and has an open top 214 opposite a bottom 216 of the first channel, and where each of the first structures has a top surface 212 extending between and joining opposing side surfaces of the first structure, coating a release layer 360 onto the top surfaces of the first structures. The release layer 360 may be deposited onto the top surfaces of the first structures 210 via direct or offset gravure coating, roll coating, brush coating, dip coating, slot dye coating, inkjet printing, flexographic printing, or gravure printing, for example. Step 2: substantially filling each first channel in 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 including a land portion 410 and a second structured major surface 601 including a plurality of second structures 610, where each second structure extends from the land portion to a top surface 612 of the second structure, and where the top surface extends between and joins opposing sidewalls 714 and 715 of the second structure. Step 4: separating the first and second films such that the second film includes the release layer disposed on the land portion. (Steps 2-4 can correspond to making film (a) of FIG. 12 from film (b) of FIG. 11.) Step 5 ((a) to (b) in FIG. 12): depositing an optically absorptive layer 250 onto the second structured major surface such that the optically absorptive layer substantially conforms to the second structured major surface. Step 6 ((b) to (c) in FIG. 12): removing the optically absorptive layer from the top surfaces of the second structures and from the release layer. The optically absorptive layer can be removed from the top surfaces by wetting the surfaces with water and rubbing with a horsehair brush, or by utilizing a tape to peel off the optically absorptive layer, for example. The optically absorptive layer can be removed from the bottom surface (the surface of the release layer) using an ultrasonic cleaning bath, for example. The remaining portions of the optically absorptive layer 250 can correspond to layer 40 described elsewhere herein. Steps 1-6 may be carried out sequentially.

In some embodiments, the optically absorptive layers remaining on the side walls of the second structures have an average height hl in a height direction substantially orthogonal to the first and second directions and an average thickness t, where hl/t > 10 (or in a range described elsewhere herein).

In some embodiments, the method further includes, between the separating step (Step 4) and the depositing the optically absorptive layer step (Step 5, which can correspond to (a) to (b) in FIG. 13), coating a release layer onto the top surfaces of the second structures. This can result in the second film 401’ of FIG. 13, for example. The release layer on the top surfaces can facilitate removal of the optically absorptive layer from the top surfaces as indicated by the change from (b) to (c) in FIG. 13, for example. In some embodiments, the method further includes, before the coating step (Step 1): forming a microreplicated 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 an organosilicon compound such as hexamethyldisiloxane (HMDSO). HMDSO can be applied via plasma deposition, for example. In some embodiments, the microreplicated layer is formed on a first substrate 160 and the second film 401 is formed on a second substrate 160’.

In some embodiments, the method further includes, after removing the optically absorptive layer from the top surfaces of the second structures and from the release layer (Step6), forming a planarization layer (e.g., by backfilling with a resin and then solidifying the resin) on the second structured major surface, where the planarization layer has a major surface substantially conforming to the second structured major surface and an opposite substantially planar major surface. The planarization layer can correspond to layer 31 of FIGS. 1-2, 5-7, or 10, for example.

FIG. 14 schematically illustrates a process for making a light control film such as light control film 300, 500, 600, 700 or 800, for example, according to some embodiments. In some embodiments, a method of making a light control film includes the following steps. Step l((a) to (b) in FIG. 14): depositing an optically absorptive layer 250 onto a first structured major surface of a first film 301 such that the optically absorptive layer substantially conforms to the first structured major surface, where 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 where each first channel is disposed between adjacent first structures and has an open top 214 opposite a bottom 216 of the first channel. Step 2((b) to (c) in FIG. 14): removing the optically absorptive layer from atop portion 212 of each first structure of the plurality of first structures, where the top portions of the first structures are adjacent to the open tops of the first channels. This can be done by wetting the surfaces with water and rubbing with a horsehair brush, or by utilizing tape to peel off the optically absorptive layer, for example. Step 3 ((c) to (d) in FIG. 14): for each first channel in the plurality of first channels, disposing a release layer 360 on the optically absorptive layer along the bottom of the first channel and along at least a portion of sidewalls of the first structures adjacent the first channel. The release layer 360 may be deposited via wire-wound rod coating, slot dye coating, notch-bar coating, gravure coating, spray coating, or inkjet printing, for example. Step 4: after the removing and disposing steps (Steps 2 and 3), substantially filling each first channel in the plurality of first channels with a resin. Step 5: solidifying the resin to form a second film 401 including a land portion 410 and a second structured major surface including a plurality of second structures 610, where each second structure extends from the land portion to a top portion 612 of the second structure, and where the top portion extends between and joins opposing sidewalls 714 and 715 of the second structure. Step 6: separating the first and second films such that the second film comprises the optically absorptive layer disposed on the sidewalls and top portions of the second structures. (Steps 4-6 can correspond to the change from (d) to (e) in FIG. 14). Step 7 ((f) to (g) in FIG. 14): for each second structure in the plurality of second structures, removing the optically absorptive layer from at least the top portion of the second structure to expose the release layer. The optically absorptive layer can be removed from the top surfaces, for example, by wetting the surfaces with water and rubbing with a horsehair brush, or by utilizing tape to peel off the optically absorptive layer, or by using a resin layer coated on a substrate and cured in contact with the optically absorptive layer to peel off the optically absorptive layer as schematically illustrated in step (f) of FIG. 14. The remaining portions of the optically absorptive layer 250 can correspond to layer 40 described elsewhere herein. Steps 1-7 may be carried out sequentially.

In some embodiments, the method includes, before the depositing step (Step 1): forming a microreplicated 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 an organosilicon compound such as hexamethyldisiloxane (HMDSO). HMDSO can be applied via plasma deposition, for example. In some embodiments, the microreplicated layer is formed on a first substrate 160 and the second film 401 is formed on a second substrate 160’.

In some embodiments, for each first channel in the plurality of first channels 222 and for each of the sidewalls adjacent the first channel, disposing the release layer on the optically absorptive layer includes disposing the release layer on no more than about 90, 80, 70, 60, 50, 40, 30, 20, or 10 percent of a height along the height direction of the optically absorptive layer along the sidewall. In some embodiments, for each first channel in the plurality of first channels 222 and for each of the side walls adjacent the first channel, disposing the release layer on the optically absorptive layer includes disposing the release layer on at least 2, 5, 10, 15, 20, 25, or 30 percent of a height along the height direction of the optically absorptive layer along the sidewall

In some embodiments, substantially filling each first channel in the plurality of first channels with a resin (Step 4) includes overcoating the first structured major surface with the resin.

In some embodiments, the method includes, after removing the optically absorptive layer from at least the top portions of the second structures (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 opposite substantially planar major surface. The planarization layer can correspond to layer 31 ’ ofFIGS. 8-9, for example, or to optical film lO of FIGS. l-2 or 6-7, for example.

Depositing the optically absorptive layer 250 in the methods of FIGS. 12-14 may be carried out 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, depositing the optically absorptive layer 250 in any of the methods of FIGS. 12-14 may be carried out via LbL self-assembly as described in U.S. Pat. Appl. Nos. 2021/0333624 (Schmidt et al.); 2022/0019007 (Schmidt et al.); and 2023/00289558 (Liu et al.), for example.

EXAMPLES

EXAMPLE 1

“Cast-and-Cure” UV Microreplication of Film Tool A diamond (29.0 pm tip width, 3° included angle, 87 pm deep) was used to cut a metal tool having a plurality of parallel linear grooves. The grooves were spaced apart by a pitch of 62.6 microns. A roll of UV microreplicated film was created to form a copy of the tool using Resin A, which was prepared by mixing the materials in the following table.

Resin A

A “cast-and-cure” microreplication process was carried out with Resin A and the tool described above. The line conditions were: resin temperature 150 °F (65.6 °C), die temperature 150 °F (65.6 °C), coater IR 120 °F (48.9 °C) edges/130 °F (54.4 °C) center, tool temperature 100 °F (37.8 °C), and line speed 70 feet per minute (fpm) (0.36 meters per second (m/s)) Fusion D lamps, with peak wavelength at 385 nm, were used for curing and operated at 100% power. The resulting microstructured film comprised a plurality of protrusions separated by channels. The base substrate layer was PET film (3M Company, St. Paul, MN), having a thickness of 2.93 mils (74.4 micrometers). The side of the PET film that contacts the resin was primed with a thermoset acrylic polymer (RHOPLEX 3208 available from Dow Chemical, Midland, MI). The land layer of the cured resin had a thickness of 8 micrometers. The protrusions of the microstructured film are a negative replication of the grooves of the tool. The protrusions have a wall angle of 1.5 degrees resulting in the protrusions being slightly tapered. The channels of the microstructured film are a negative replication of the uncut portions of the tool between the grooves.

HMDSO Release-Treatment of Microchannels:

A release treatment was deposited onto the UV microreplicated channel film from ‘“Cast-and- Cure’ UV Microreplication of Film Tool” using a home-built parallel plate capacitively coupled plasma reactor as described in U.S. Patent No. 6,696,157 (David et al.). The chamber had a central cylindrical powered electrode with a surface area of 18.3 ft². After placing the film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). In a first step, the film was exposed to an oxygen etch wherein 02 was flowed into the chamber at a rate of 1000 SSCM, with an RF power frequency of 13.56 MHz and an applied power of 2000W. The etching exposure was controlled via line speed at 30fpm, resulting in an approximate etch time of 10 seconds. The oxygen was turned off, and HMDSO gas was introduced to the chamber with a RF power of 2000W. The fdm was then run backwards through the reactor at 20fpm, resulting in an approximate HMDSO release treatment time of 15 seconds. After completion of the treatment, the RF power and gas supply were stopped, and the chamber was returned to atmospheric pressure.

Printing Release Layer and Replication from Film Tool

The upper horizontal surfaces of the HMDSO-treated microreplicated channel film (e.g., corresponding to film 301 of FIG. 11) were selectively coated and partially cured with a release ink. TEGO 702 was used as the release ink and was deposited at 5 ft/min via roll-to-roll gravure coating, utilizing a 1.0 BCM/in² gravure roll. The release-patterned substrate was then transported through a 385nm UV LED array whose output irradiance 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 surfaces of the HMDSO-treated microstructured substrate. The partially cured release-coated microstructured substrate was then transported to the back end of the coating line where a backfilling “cast-and-cure” microreplication process step was performed using Resin A. The substrate was transported through the line until reaching a section before a lamination nip against a temperature- controlled backup roll. A peristaltic pump (Watson Marlow 505UD) was set up with 1/8” tubing at 5 RPM to deliver solution via a point source to the center of the release-coated microstructured channel film. The film was transported into a 90-durometer rubber roll nipped against a steel roller set at 130 degrees F with pneumatic cylinders (Bimba, University Park, IL) with a pressure of 40 psi. A 5 mil ST504 (DuPont, Midland, MI) PET was laminated against the release-coated film with Resin A, spreading the resin out to the extents 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 the inverse structure, creating a clear channel film (e.g., corresponding to film 401 of FIG. 12) with transferred TEGO 702 release coating to the bottoms of the channels. The resultant “clear channel film” made from Resin A on 5 mil PET was then transported to a winder and wound into a roll.

Layer-by-Layer Coating on the Clear Channel Film

Three separation coating solutions were prepared: Cation and Core Anion, and Clad Anion. The Cation 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 Anion solution was 2.5% solids EXPCB (anionic surface-modified carbon black from Cabot) with 50 mM NaCl and 0.1% PL92. The Clad Anion solution was 4.0% solids CARBOSET CR-3090 (anionic acrylic styrene emulsion from Lubrizol), 0.5% solids EXPCB, 50 mM NaCl, and 0.1% PL92. The coating construction was a cladded core as described in U.S. Pat. Appl. No. 2021/0333624 (Schmidt et al.). Six bilayers of Cation/Clad Anion were deposited, followed by four bilayers of Cation/Core Anion, followed by six bilayers of Cation/Clad Anion for a total of 16 bilayers. The black coating was coated conformally on the clear channel film via layer-by-layer (LbL) deposition using a spray coater purchased from Svaya Nanotechnologies, Inc. (Sunnyvale, CA) and modeled after the system described in US Pat. No. 8234998 (Krogman et al.) as well as Krogman et al. Automated Process for Improved Uniformity and Versatility of Uayer-by-Uayer Deposition, Uangmuir 2007, 23, 3137-3141. The apparatus comprises pressure vessels loaded with the coating solutions. Spray nozzles with a flat spray pattern (from Spraying Systems, Inc., Wheaton, IU) were mounted to spray the coating solutions and rinse water at specified times, controlled by solenoid valves. The pressure vessels (Alloy Products Corp., Waukesha, WI) containing the coating solutions were pressurized with nitrogen to 30 pounds per square inch (psi) (0.21 MPa), while the pressure vessel containing DI water was pressurized with air to 30 psi (0.21 MPa). Flow rates from the coating solution nozzles were each 10 gallons per hour (38 Uiters/hour), while flow rate from the DI water rinse nozzles were 40 gallons per hour (150 Uiters/hour). The substrate to be coated (9 inch x 12 inch) (23 cm x 30 cm) was adhered at the edges with epoxy (Scotch-Weld epoxy adhesive, DP100 Clear, 3M Company, St. Paul, MN) 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), which was mounted on a vertical translation stage and held in place with a vacuum chuck. In a typical coating sequence, the polycation solution was sprayed onto the substrate while the stage moved vertically downward at 76 millimeter/second (mm/sec). Next, after a dwell time of 12 sec, the DI water was sprayed onto the substrate while the stage moved vertically upward at 102 mm/sec. The substrate was then dried with an airknife at a speed of 3 mm/sec. Next, the polyanion solution was sprayed onto the substrate while the stage moved vertically downward at 76 mm/sec. Another dwell period of 12 sec was allowed to elapse. The DI water was sprayed onto the substrate while the stage moved vertically upward at 102 mm/sec. Finally, the substrate was then dried with an airknife at a speed of 3 mm/sec. The above sequence was repeated to deposit a number of “bi-layers” denoted as (Polycation/Polyanion)n where n is the number of bi-layers. The coated substrate (e.g., polymer film) was stripped off of the glass prior to subsequent processing.

Removal of LbL Coating from the Upper Horizontal Surfaces

Following LbL coating of the channel film with the release material (TEGO 702) selectively located in the recesses of the microstructured substrate, it was desired to first remove the LbL-coated opaque layer from the upper horizontal surfaces. This was simply done by depositing DI water liberally over the surface of the LbL-coated substrate and gently rubbing the surface with a horsehair brush (All Printing Resources, Glendale Heights, IL) for approximately 30 seconds and until it was apparent the upper surface was free of the LbL coated opaque layer. Removal of LbL Coating from the Lower Horizontal Surfaces

After removing the LbL coating layer from the upper horizontal surfaces, the LbL coating was removed from the bottom horizontal surfaces. This was done by placing the sample in a benchtop ultrasonic cleaning bath (Crest, Ewing, NJ) composed of 40g Altrawash Green (Harper, De Pere, WI) and 1500g of tap water. The temperature of the bath was set to 30C and the ultrasonic power was set to between 1 and 3. The sample was left in the bath for approximately 1-2 minutes, until it appeared as if the sample was free of any material in the bottom of the channels. An SEM image of the film after washing is shown in FIG. 15. It can be seen that the LbL coating is no longer on the bottom horizontal surfaces. The resulting light control film, as measured by a HazeGard II (BYK-Gardner, Geretsried, Germany), had a total transmission of 88%.

EXAMPLE 2

Resin B was prepared by mixing the materials in the following table.

Resin B

Microchannel Formation

A microchannel film (corresponding to film 301 of FIG. 14, for example) used for these experiments was formed via “cast-and-cure” UV microreplication of Resin B onto PET, using the same metal tool and similar processing conditions as described in Example 1.

HMDSO Release-Treatment of Microchannels

A release treatment was deposited onto the microchannel film from “Microchannel Formation” using a home-built parallel plate capacitively coupled plasma reactor as described in U.S. Patent Nos. 6,696,157 (David et al.). The chamber had a central cylindrical powered electrode with a surface area of 18.3 ft². After placing the film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). In a first step, the film was exposed to an oxygen etch wherein 02 was flowed into the chamber at a rate of 1000 SSCM, with an RF power frequency of 13.56 MHz and an applied power of 2000W. The etching exposure was controlled via line speed at 30fpm, resulting in an approximate etch time of 10 seconds. The oxygen was turned off, and HMDSO gas was introduced to the chamber with a RF power of 2000W. The film was then run backwards through the reactor at 20fpm, resulting in an approximate HMDSO release treatment time of 15 seconds. After completion of the treatment, the RF power and gas supply were stopped, and the chamber was returned to atmospheric pressure.

Layer-by-Layer Deposition of Opaque (Carbon-Black) Conformal Coating

Following release treatment of the microchannel fdm, an opaque conformal coating was deposited on the surface of the HMDSO-treated microchannel film. The conformal layer was deposited by layer-by-layer (LbL) deposition. Three separation coating solutions were prepared: Cation, Core Anion, and Clad Anion. The Cation solution was 2.5% solids SANCURE 20072 (cationic polyurethane dispersion from Lubrizol) with 200 mM sodium chloride (NaCl) and 0.1% PLURONIC L92 (PL92) (nonionic surfactant from BASF). The Core Anion solution was 2.5% solids EXPCB (anionic surface- modified carbon black from Cabot) with 50 mM NaCl and 0.1% PL92. The Clad Anion solution was 4.0% solids CARBOSET CR-3090 (anionic acrylic styrene emulsion from Lubrizol), 0.5% solids EXPCB, 50 mM NaCl, and 0.1% PL92. The coating construction was a cladded core as described in U.S. Pat. Appl. Nos. 2021/0333624 (Schmidt et al.). A belt of the microstructured film about 125 feet in length was threaded through the continuous LbL coater. Six bilayers of Cation/Clad Anion were deposited, followed by four bilayers of Cation/Core Anion, followed by six bilayers of Cation/Clad Anion for a total of 16 bilayers. The solutions were coated onto the microstructured film with a #4 Mayer Rod fed with needles from a liquid delivery manifold at a flow rate of about 200 mL/min at each coating station. Excess coating solutions were removed from the web with airknives gapped at 40 mil to the web with pressure of about 35 psi. Line speed was 50 feet per minute. The resulting opaque coating was approximately 1 micron thick as measured by cross-sectional scanning electron microscopy (SEM).

Adhesive Transfer of Opaque Coating from First Upper Surface of Microchannel Film

The opaque conformal 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 surfaces.

Coating of Releasing Layer

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

Inversion of Microchannel Film to Form Daughter with Transferred Opaque Coating

The remaining opaque film (covering the HMSDO-treated channel sidewalls and bottoms) was transferred to a replicate daughter substrate. This was done by squeeze film lamination of photo-curable resin between the sample from “Coating of Releasing Layer” and a 5 mil thick nano-roughened PET film, using a Chemlnstruments Hot Roll Laminator. The lamination stack was transported via a conveyor through a Fusion mercury arc lamp configured with a H-Bulb to solidify the photo-curable resin. The hardened lamination stack was separated by peeling the PET from the lamination stack to form a daughter replicate in cured resin, with three sides of the microchannel covered by the opaque coating. The opaque coating now covered the sidewalls and upper surface of the replicated daughter substrate (e.g., as schematically illustrated for film (e) in FIG. 14).

Removal of Opaque Coating from Second Upper Surface of Daughter Microchannel Film

A film of nano-roughened PET film was coated with roughly 3 microns of Resin A by coating a solution of 50 wt% Resin A in MEK with a #3 Meyer rod. This PET film was laminated to the daughter film from “Inversion of Microchannel Film to Form Daughter with Transferred Opaque Coating” using a Chemlnstruments Hot Roll Laminator with zero extra 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 absorptive layer (i.e. the opaque coating) from the upper surfaces and upper portions of the sidewalls. FIG. 16 is an SEM image of the resulting light control film. The on-axis transmission of the light control film was measured to be 75-78% using the HazeGard II.

Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1. 1, and that the value could be 1.

Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially” with reference to a property or characteristic is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description and when it would be clear to one of ordinary skill in the art what is meant by an opposite of that property or characteristic, the term “substantially” will be understood to mean that the property or characteristic is exhibited to a greater extent than the opposite of that property or characteristic is exhibited.

All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations, or variations, or combinations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed is:

1. A light control film comprising an optical film shaped to define a plurality of substantially linear alternating ridges and grooves extending along substantially a same first direction and arranged along an orthogonal second direction, each of the grooves comprising first and second layers disposed therein and stacked along a thickness direction of the light control film, each of the first and second layers having a maximum thickness of greater than about 0.01 microns, the second layer disposed between the first layer and a bottom of the groove, wherein, for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, an interface layer that is substantially coextensive along the first direction with the ridge 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 of greater than about 0.01 microns and less than about 10 microns.

2. The light control film of claim 1, wherein, for each pair of adjacent ridge and groove in 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 of claim 1, wherein in a planar cross-section of the optical film that is substantially orthogonal to the light control film and the first direction, each of the ridges has maximum width that is within 20% of a minimum width of the ridge.

4. The light control film of claim 1, wherein the second layers are less than about 10 microns thick and the first layers are greater than about 10 microns thick.

5. The light control film of claim 1, wherein the first layers have substantially a same first composition and the second layers have substantially a same second composition different from the first composition.

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

7. The light control film of claim 1, wherein for each pair of adjacent ridge and groove in the plurality of alternating ridges and grooves, each of the bottom of the grove and a top of the ridge is substantially free of any light absorbing layer.

8. The light control film of claim 1, wherein the interface layer is substantially light absorbing having an optical density of greater than about 0.1.

9. A light control film comprising a structured major surface extending continuously across substantially an entire length and an entire width of the light control film and comprising a plurality of structures, each of the structures comprising a top surface extending between and joining opposing side surfaces, such that for each pair of adjacent first and second structures in 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 connected to each other 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 and second side surfaces; and a same second layer having a same second composition different than the first composition, coats at least a majority of the connecting surface portion and coats adjacent portions of the first and second side surfaces.

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

11. The light control film of claim 9, wherein for each pair of adjacent first and second structures in the plurality of structures, the second layer coats portions of each of the first and second side surfaces.

12. A light control film comprising a structured major surface extending continuously across substantially an entire length and an entire width of the light control film and comprising a plurality of structures, each of the structures comprising a top surface extending between and joining opposing side surfaces of the structure, such that for each structure in 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 than 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.

13. The light control film of claim 12, wherein for each structure in 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.

14. The light control film of claim 13, wherein for at least one side surface of each of at least some of the structures in 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 over the structured maj or surface and substantially filling spaces 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 of the first or second layers.