Coatings with bilayer arrangements

Abstract

A film includes a substrate and a coating deposited on the substrate. The coating includes a plurality of bilayers, each bilayer including two layers of different materials. Each of the two layers of different materials may include an oxide, a metal oxide, an alkoxide, a metalcone, or an oxynitride. Each of the two layers of different materials may have a thickness of between about 3 nanometers and about 30 nanometers. The coating may have a thickness of between about 20 nanometers and about 100 nanometers. The film with its nanometer-scale coating may be used for food packaging and other applications.

Description

Coatings with Bilayer ArrangementsCross-Reference to Related Applications

[0001] This application claims priority to and the benefit of US provisional patent application no. 63 / 457,626, filed Apr. 6, 2023, which is incorporated herein by reference.Field

[0002] The present disclosure relates to coatings and deposition of coatings onto film, particularly, nanometer-scale coatings.Background

[0003] Coatings are used on flexible materials for a wide range of packaging applications. Examples include, but are not limited to, coatings that protect the products contained in the packaging (e.g., foodstuffs) from external factors, coatings that provide antimicrobial properties (e.g., packaging for healthcare products), and coatings that serve other purposes

[0004] Barrier coatings may be used on flexible packaging materials to protect products from external factors that include, but are not limited to, water vapor, water, oxygen, light, aromas, grease, and foreign matter. Protection from these external factors is useful to extend the shelf-life of the product and ensure it is safe for use or consumption.Summary

[0005] According to an aspect of the present disclosure, a film includes a substrate and a coating deposited on the substrate. The coating includes a plurality of bilayers, each bilayer including two layers of different materials.

[0006] Each of the two layers of different materials may include an oxide, a metal oxide, an alkoxide, a metalcone, or an oxynitride.

[0007] Each bilayer may include a layer of aluminum oxide and a layer of zinc oxide.

[0008] A bilayer adjacent the substrate may have its layer of aluminum oxide in contact with the substrate.

[0009] At least two bilayers of the plurality of bilayers may have uniform thickness.

[0010] At least two bilayers of the plurality of bilayers may have different thickness.

[0011] In at least one of the bilayers of the plurality of bilayers, the two layers of different materials may have uniform thickness.

[0012] In at least one of the bilayers of the plurality of bilayers, the two layers of different materials may have different thickness.

[0013] The plurality of bilayers may number between 2 and 12.

[0014] Each of the two layers of different materials may have a thickness of between about 3 nanometers and about 30 nanometers.

[0015] The coating may have a thickness of between about 20 nanometers and about 100 nanometers.

[0016] A layer of the coating that is in contact with the substrate may be thicker than other layers of the coating.

[0017] The film may further include an additional substrate including a base material and an ink layer disposed on the base material and an adhesive layer adhering the additional substrate to the coating.

[0018] The substrate may include a base material and an ink layer and the coating may be deposited on the ink layer.

[0019] The film may further include an additional substrate and an adhesive layer adhering the additional substrate to the coating.

[0020] The substrate may include a base material onto which the coating is deposited and the packaging film may further include an ink layer disposed on the coating.

[0021] The film may further include an additional substrate and an adhesive layer adhering the additional substrate to the ink layer.

[0022] The substrate may include a base material and a pre-coat and the coating may be deposited on the pre-coat.

[0023] The film may further include a top coat disposed on the coating.

[0024] The substrate may include polylactic acid.

[0025] The substrate may include paper.

[0026] The film may further include lamination.

[0027] The two layers of different materials may be formed using a coreactant or oxidant.

[0028] The film may be a food packaging film.

[0029] According to another aspect of the present disclosure, a film includes a substrate and a coating deposited on the substrate. The coating includes a plurality of bilayers, each bilayer including two layers of different materials. Each of the two layers of different materials includes an oxide, a metal oxide, an alkoxide, a metalcone, or an oxynitride. Each of the two layers of different materials has a thickness of between about 3 nanometers and about 30 nanometers. The coating has a thickness of between about 20 nanometers and about 100 nanometers.

[0030] A layer of the coating that is in contact with the substrate may be thicker than other layers of the coating.

[0031] According to another aspect of the present disclosure, a method of making a film includes alternately depositing two layers of different materials onto a substrate to form a bilayer. The bilayer has a thickness on a scale of nanometers. The method further includes successively forming a plurality of the bilayers to form a coating on the substrate.Brief Description of the Drawings

[0032] FIG. 1 is a cross-sectional view of an example film including a barrier coating disposed on a substrate, where the barrier coating includes bilayers with each bilayer having two layers ofdifferent materials.

[0033] FIG. 2 is a cross-sectional view of an example film including a barrier coating with base material on both sides, an ink layer, and an adhesive layer.

[0034] FIG. 3 is a cross-sectional view of another example film including a barrier coating with base material on both sides, an ink layer, and an adhesive layer.

[0035] FIG. 4 is a cross-sectional view of another example film including a barrier coating with base material on both sides, an ink layer, and an adhesive layer.

[0036] FIG. 5 is a cross-sectional view of an example film including a barrier coating with a top coat and pre-coat.

[0037] FIG. 6 is a cross-sectional view of another example film including a barrier coating with a pre-coat.

[0038] FIG. 7 is a cross-sectional view of another example film including a barrier coating with a top coat.

[0039] FIG. 8 is a cross-sectional view of an example bilayer arrangement of a barrier coating having a thicker first layer.

[0040] FIG. 9 is a cross-sectional view of another example bilayer arrangement with bilayers of different thickness.

[0041] FIG. 10 is a cross-sectional view of another example bilayer arrangement with material layers of different thickness within a bilayer.

[0042] FIG. 11 is a diagram illustrating a spatial atomic layer deposition (SALD) process to deposit a barrier coating.

[0043] FIG. 12 is a diagram illustrating an SALD apparatus to deposit a barrier coating.Detailed Description

[0044] Disclosed herein are films, coatings, and methods of making such, particularly, with ananometer scale. The techniques discussed herein aim to provide durable and resilient coatings, so as to improve coating performance.

[0045] FIG. 1 shows an example film 100 with a coating 102 disposed on a substrate 104. The coating 102 is a barrier coating and the examples provided herein relate to barrier coatings. While the techniques discussed herein are particularly suited to barrier coatings, they are not limited to barrier coatings.

[0046] The film 100 may be used for packaging, such as food packaging (e.g., sealed bags or packages that contain food or ingredients, such as snacks, meat, cheese, etc.) , personal care products (e.g., creams, lotions, gels, etc.), pharmaceuticals, sterile medical products or instruments, agricultural products, and similar products that benefit from protection against degradation or contamination and / or that require a relatively long shelf life. The substrate provides mechanical strength to the film 100 and the barrier coating 102 provides a barrier against material (e.g., oxygen, water, gases, particles, contaminates, etc.) that may otherwise pass into or through the substrate 104. The barrier coating 102 is deposited onto the substrate 104 by spatial atomic layer deposition (SALD).

[0047] Packaging is a suitable application for the techniques discussed herein but is not the only application. As such, the present disclosure is not limited to packaging film. It should be apparent that the teachings and examples provided herein as related to packaging film may be used for or readily adapted to other applications.

[0048] The substrate 104 is flexible and may include a base material, such as polylactic acid (PLA), paper, paperboard, polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyurethane (PU), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), starch- based polymer, seaweed-based polymer, or similar. The substrate 104 may include additional materials or layers thereof, such as an ink layer or pre-coat (also termed a primer). The substrate 104 may be selected to be biodegradable, recyclable, or compostable.

[0049] It is contemplated that a substrate 104 with roughness features with a peak or valley size of less than about 0.2 millimeters may be used without undue difficulty.

[0050] It is contemplated that, if the substrate 104 has pinholes, the pinholes should have anominal width of less than about 10 nanometers, so that the barrier coating 102 may close the pinholes reliably.

[0051] Useful substrates 104 may have a broad range of surface chemistries. Oxygen (O) groups at the surface are particularly useful. A precursor chemical used when forming the barrier coating 102 may react with O groups, which facilitates coating deposition. Examples of base materials and primers that have such O groups include PLA, PET, polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), and acrylic, for example.

[0052] No particular treatment to enhance surface energy is required for the substrate 104, as it has been found that the barrier coating 102 adheres satisfactorily to the substrate 104 without such treatment.

[0053] Inline surface treatment may help remove dust and particles to improve surface cleanliness and prevent pinhole formation. Example surface treatments (also termed pretreatment) include corona treatment, plasma treatment (e.g., argon plasma), and flame treatment. Pretreating the surface prior to applying the barrier coating 102 may help with coating deposition by, for example, smoothing the surface in a way that improves the bonding of the coating 102. The barrier coating 102 may conformally coat the surface and encapsulate any dust particles and thus surface treatment may be used but is not expected to be required in many cases.

[0054] Regarding thermomechanical properties of the substrate 104, in many examples it is useful if the substrate does not bulge significantly when heated. The substrate should retain its shape without deforming at least up to the desired coating temperature. The glass transition temperature of the substrate should ideally be above the coating temperature. A lower coefficient of thermal expansion (CTE) of the substrate tends to reduce the chance of thermal stress cracking of the barrier coating 102 due to CTE mismatch between the barrier coating 102 and the substrate 104. In various examples, the substrate 104 material is selected to have a CTE that is consistent with or lower than the CTE of PP, PE, PLA, PVOH, or PU.

[0055] The barrier coating 102 includes a stack of bilayers 106. Any suitable number of bilayers 106 may be used. In various examples, between 2 and 12 bilayers may be stacked to form thebarrier coating 102.

[0056] Each bilayer includes two layers of different materials 108, 110. The term “two” and similar terms used herein are open-ended unless otherwise specified. In this example, two layers means two or more layers, and a bilayer may be a tri-layer, etc.

[0057] A particular bilayer 106 design may be repeated to form a stack of bilayers 106 that forms the barrier coating 102. Repetition of bilayers 106 provides robustness in that a particular layer of material 108, 110 may crack or exhibit a flaw without compromising the integrity of the barrier coating 102 as a whole. Multiple layers of material 108, 110 may experience localized failure while still providing an effective coating overall.

[0058] In various examples, each bilayer 106 may have a thickness of between about 3 nanometers and about 30 nanometers. More specifically, each bilayer 106 may have a thickness of between about 4 nanometers and about 14 nanometers. In various examples, the barrier coating 102 may have a total thickness of between about 20 nanometers and about 100 nanometers. More specifically, the barrier coating 102 may have a total thickness of between about 30 nanometers and about 90 nanometers.

[0059] The bilayers 106 generally have the same layers of materials 108, 110, though the thicknesses of the materials 108, 110 may differ among the bilayers 106. For example, the layer of material in contact with the substrate 104 may be thicker than other layers of material that are not in contact with the substrate 104. Such a thicker layer of material may help even out surface roughness of the substrate 104 to promote barrier coating effectiveness. A thicker first layer may also be used to begin forming the expected multilayered coating after fewer layers, as the first layer may penetrate into the substrate instead of forming a neat layer. That is, the first layer may be provided with a larger nominal thickness than otherwise required by the intended bilayer arrangement to account for substrate roughness or unpredictability in initial deposition onto the substrate. If the first layer is too thin, it may compromise the intended building up of the subsequent layer or layers. In that sense, the first layer may be considered to be a mechanical buffer between the substrate and the balance of the coating layers.

[0060] Each layer of material 108, 110 may include an oxide, a metal oxide, an alkoxide, ametalcone (e.g., an “alucone” or “zincone”), oxynitride, or similar material. For example, each bilayer 106 may include a layer of aluminum oxide 108 and a layer of zinc oxide 110. Aluminum oxide may act as the main gas barrier material. Zinc oxide may act as a structural layer and may provide other benefits, such as ultraviolet (UV) light blocking. In various examples, the bilayers 106 may be configured and arranged so that an aluminum oxide layer 108 contacts the substrate 104. In other examples, the bilayers 106 may be configured and arranged so that zinc oxide layer 110 contacts the substrate 104, which may improve barrier performance against moisture. The substrate-contacting layer (which may be termed a nucleation layer) may be thicker than the other layers. In still other examples, other materials, such as tin oxide, silicon oxide, and titanium dioxide, may be used.

[0061] FIG. 2 shows an example film 200, such as a packaging film, that uses a barrier coating 102 discussed above.

[0062] The barrier coating 102 is applied to a first substrate that includes a base material 202, such as paper, PLA, etc. (see above for more examples). The barrier coating 102 may be deposited directly onto the base material 202.

[0063] The film 200 includes an additional, second substrate that includes a base material 204 and an ink layer 206 disposed on the base material 204. The base material 204 may be paper, PLA, etc. (see above for more examples). The ink layer 206 may be printed onto the base material 204. The ink layer 206 may not completely cover the base material 204. That is, ink may be selectively deposited to form imagery and text, leaving some of the base material 204 exposed.

[0064] The film 200 further includes an adhesive layer 208 that adheres the second substrate formed of the base material 204 and ink layer 206 to the barrier coating 102. The adhesive layer 208 joins the first substrate (i.e., base material 202) with the barrier coating 102 to the second substrate (i.e., base material 204 and ink layer 206). The adhesive layer 208 may be applied after the two portions of the film 200 are individually completed.

[0065] FIG. 3 shows an example film 300, such as a packaging film, that uses a barrier coating 102 discussed above.

[0066] The film 300 includes a first substrate that includes a base material 302 and an ink layer 304. The base material 302 may be paper, PLA, etc. (see above for more examples). Ink may be printed onto the base material 302 to form the ink layer 304. Depending on the amount of printing, the ink layer 304 may not completely cover the base material 302.

[0067] The barrier coating 102 is deposited on the first substrate. More specifically, the barrier coating 102 is deposited onto the ink layer 304 and onto any portion of the base material 302 that is not covered by the ink layer 304.

[0068] The film 300 includes an additional, second substrate that includes a base material 306, such as paper, PLA, etc. (see above for more examples).

[0069] An adhesive layer 308 adheres the first substrate (z.e., base material 302 and ink layer 304) with the barrier coating 102 to the second substrate (z.e., base material 306). The adhesive layer 308 may be applied after the two portions of the film 300 are individually completed.

[0070] FIG. 4 shows an example film 400, such as a packaging film, that uses a barrier coating 102 discussed above.

[0071] The film 400 includes a first substrate that includes a base material 402, such as paper, PLA, etc. (see above for more examples). The barrier coating 102 may be deposited directly onto the base material 402.

[0072] The film 400 includes an ink layer 404 disposed on the barrier coating 102. Ink may be printed onto the barrier coating 102 to form the ink layer 404. Depending on the amount of printing, the ink layer 404 may not completely cover the barrier coating 102.

[0073] The film 400 further includes an additional, second substrate that includes a base material 406, such as paper, PLA, etc. (see above for more examples).

[0074] An adhesive layer 408 adheres the second substrate to the first substrate. That is, the adhesive layer 408 bonds the base material 406 to the ink layer 404 and any portion of the barrier coating 102 that is not covered by the ink layer 404. The adhesive layer 408 may be applied after the two portions of the film 400 are individually completed.

[0075] The example films 200, 300, 400 may further include a heat-sealing layer, such as a layer of PE, applied to the exposed face of a base material to facilitate heat sealing a package closed, which is particularly useful for food packaging or the packaging of similar products. Good sealing is important to avoid leakage, intrusion, contamination that would defeat the purpose of the barrier coating.

[0076] The example films 200, 300, 400 may be considered 2-ply films, in that each base material with its accompanying layer(s) forms one ply. In other examples, a similar film may be provided with any suitable number of additional plies, such as a ply of plastic, aluminum foil, or functionalized film, to form a 3- or 4-ply film that provides similar utility and benefit.

[0077] FIG. 5 shows an example film 500, such as a packaging film, that uses a barrier coating 102 discussed above.

[0078] The film 500 includes a substrate that includes a base material 502 and a pre-coat 504.

[0079] The barrier coating 102 is deposited on the pre-coat 504, which may be termed a primer. The pre-coat 504 is useful to fill pores in a paper base material, create a smooth and even layer for the barrier coating 102, provide compatible surface chemistry for the barrier coating (e.g., a primer with oxygen groups when the barrier coating 102 includes a metal oxide). Example materials for the pre-coat 504 include PVOH, EVOH, acrylic, polyurethane (PU), nanocellulose / micro fibrillated cellulose, PLA coating, PE coating, or similar.

[0080] The film 500 further includes a top coat 506 disposed on the barrier coating 102. The top coat 506 may be useful to protect the barrier coating 102 from downstream processes, such as conveyance. For example, if the barrier coating 102 touches a roller it may be damaged (e.g., scratched). A suitable top coat 506 may protect against such damage. A suitable top coat 506 may improve resistance against flexure failure of the barrier coating 102.

[0081] A top coat 506 may also provide separation from particulates found in inks which could damage the barrier coating 102. As such, a top coat 506 may be provided over the barrier coating 102, in this example and in other examples (see FIG. 2 to 4) where the barrier coating 102 contacts ink to guard against such damage.

[0082] Example top coats 506 include a PE layer for heat sealing and other materials discussed above as useful for the pre-coat 504.

[0083] In various examples, the top coat 506 may be made of the same material as the base material 502, which improves recyclability.

[0084] The example film 500 may be considered a 1-ply film. In other examples, a similar film may be provided with any suitable number of additional plies, such as a ply of plastic, aluminum foil, or functionalized film, to form a 2-, 3-, or 4-ply film that provides similar utility and benefit.

[0085] FIG. 6 shows an example film 600, such as a packaging film, that uses a barrier coating 102 discussed above. The description of the film 500 above may be referenced for detail not repeated here.

[0086] The film 600 includes a substrate that includes a base material 502 with a pre-coat or primer 504. A barrier coating 102 is deposited on the base material 502, i.e., onto the pre-coat or primer 504.

[0087] FIG. 7 shows an example film 700, such as a packaging film, that uses a barrier coating 102 discussed above. The description of the film 500 above may be referenced for detail not repeated here.

[0088] The film 700 includes a substrate that includes a base material 502 without a pre-coat or primer 504. A barrier coating 102 is deposited on the base material 502. A top coat 506 is deposited over the base barrier coating 102.

[0089] With regard to the examples provided in FIGs. 2 - 7, it should be noted that other examples derivable from these examples are also contemplated. Further, various known pre-coat and top-coat materials provide some degree of barrier. The barrier coating 102 described herein may be useful to combine with such materials to further enhance barrier performance.

[0090] Still with regard to the examples provided in FIGs. 2 - 7, further enhancements may be provided, such as lamination, a top-coat sealant, or similar. For example, lamination of the examples with a PE layer using an industrial laminating process can help to protect the barrier coating, especially in cases where the barrier coating is exposed, such as in the example of FIG.6. Alternatively, an overprint varnish layer such as acrylic can be applied with flexographic or screen printing. Making a top coat or lamination layer (e.g., see layers 506 in FIGs. 5 and 7) of the same material as the base material may provide advantages for recycling purposes.

[0091] FIGs. 8 - 10 show further detail of example bilayers with example thicknesses shown. These examples show that variable material thicknesses are possible and may be desirable in certain applications.

[0092] FIG. 8 shows an arrangement 800 with a uniform bilayer 802 of first and second materials 108, 110 that is repeated. Each layer of material of the bilayer 802 is deposited at the same nominal thickness (e.g., 5 nm), except for the initial layer 804 of first material 108 that is thicker to promote adherence to the substrate 104.

[0093] FIG. 9 shows an arrangement 900 with variable bilayers 902, 904 of first and second materials 108, 110. Each bilayer 902, 904 has material layers 108, 110 of the same nominal thickness (e.g., 4 or 5 nm) and this thickness may be varied between the bilayers 902, 904.

[0094] FIG. 10 shows an arrangement 1000 with a bilayer 1002 of first and second materials 108, 110 that have different nominal thickness (e.g., 3 and 5 nm).

[0095] The principles shown in FIGs. 8 - 10 may be combined to meet the needs of various applications. In general, bilayers may have uniform or different thicknesses and the material layers that form each bilayer may have consistent or variable thicknesses among different bilayers

[0096] With reference to FIG. 11, the barrier coatings 102 discussed herein may be deposited onto a substate using SALD. An example SALD process generally includes ejecting working gas (e.g., precursor gas, reactant gas, inert gas, etc.) via one or more slits 1100 and withdrawing exhaust gas via one or more slits 1102, in which the slits 1100, 1102 communicate the gas with a network of channels within a structure that may be termed a SALD coater or head. This reduces or eliminates the need for evacuation and purge steps that make traditional ALD slow, such that SALD can be one to two orders of magnitude faster than conventional ALD. SALD can produce ultra-thin coatings of materials (e.g. metal oxides) that are compact, conformal, and pinhole-free and can deposit the coatings under open-air conditions and pressures, and at room or lowtemperatures, without the need for a vacuum chamber. SALD is scalable and compatible with roll-to-roll manufacturing and has been demonstrated to work on variety of surfaces including, but not limited to, plastics and paper. More information on ALD and SALD can be found in PCT publication WO2021119829, entitled “Apparatus and Method for Thin Film Deposition”, filed on December 18, 2020, which is incorporated herein by reference.

[0097] FIG. 12 shows an example spatial atomic layer deposition apparatus 1200 operable to deposit a barrier coating 102. The apparatus 1200 includes a SALD head 1202, a conveyance system 1204, and a gas-delivery system 1206. A heater 1208 may be provided at the SALD head 1202. Any suitable number of SALD heads 1202 may be used to deliver any suitable combination of gases by the gas-delivery system 1206 to deposit a barrier coating 102 onto a flexible substrate conveyed past the SALD head 1202 by the conveyance system 1204. The flexible substrate may be conveyed in one or both directions past one or multiple SALD heads 1202 to build up the barrier coating 102.

[0098] The conveyance system 1204 may include rollers 1210, web guides 1212, nip rollers 1213, idlers 1214, dancers 1216, load cells 1218, and like components positioned between an unwinder 1220 and a winder 1222 to convey a flexible substrate material 1224, such as a thin sheet or membrane of material (sometimes called a “film,” particularly in the packaging industry, but this is not to be confused with the thin film or coating being deposited). With the convenance system 1204, the flexible substrate material 1224 may be unwound from a roll at the unwinder 1220, coated by the SALD head 1202, and wound onto another roll at the winder 1222. The positioning of the rollers may be used to position flexible material relative to one or more SALD heads 1202 and may be used to control the distance between the surface of the flexible material 1224 and the surface of the SALD head 1202.

[0099] The gas-delivery system 1206 includes vessels 1230, 1232, 1234 with inert gas (e.g., nitrogen), precursor (e.g., trimethylaluminum, A1(CH3)3, for aluminum oxide), and reactant (e.g., an oxidant such as H2O), mass flow controllers 1236, on-off valves 1238, and gas lines 1240 that fluidly connect these components. Each gas line 1240 may deliver to the SALD head 1202 pure or a mixture of an inert gas, precursor, and reactant, at a flow rate controlled by respective mass flow controller(s) 1236 and on-off valve(s) 1238. The configuration and arrangement of thecomponents in FIG. 12 represent an example. In other examples, the components may have different configurations and arrangements.

[0100] Various reactants (also termed coreactants) or oxidants may be provided to react with a metal or compound containing a metal, such as aluminum or zinc, to form a layer of a barrier coating. Examples of coreactants and oxidants include water, oxygen, ethanediol, and oxygen plasma, among others. Coreactants / oxidants may be alternated each layer. For example, different coreactants / oxidants may be used for the alternating materials of a bilayer. Coreactants / oxidants can help to increase the density of certain layers.

[0101] The gas lines 1240 may be tubes made of chemically stable or inert material, such as stainless steel or Teflon, connected between components upstream of the SALD head 1202. Such components may include an inert gas vessel 1230, chemical-containing vessels (e.g., bubblers) 1232, 1234, mass flow controllers 1236, and on-off valves 1238. This gas delivery system 1206 serves the purpose of delivering one or more precursor gases, one or more reactant gases, and one or more inert gases, in pure form or suitable mixtures, to the SALD head 1202. The inert gas vessel 1230 supplies inert, non-reactive gas to the SALD head 1202 and may also be used to carry precursor gas from a precursor gas vessel 1234 and / or reactant gas from a reactant gas vessel 1232 to the SALD head 1202. The pressure of the inert gas may be regulated by one or more pressure regulators. The precursor and reactant gases may be generated by techniques such as, but not limited to, bubbling a liquid chemical with the inert gas, nebulizing a liquid chemical, by heating a liquid or solid chemical, direct liquid injection where a liquid chemical precursor is introduced to a vaporizer which vaporizes the liquid and ejects gas out of a nozzle, or a combination thereof. Chemical vapors may also be supplied in the gaseous state from a storage tank, or generated by another device, such as an ozone generator, which may be used to generate a reactant gas. The flow rates of the inert gas, one or more precursor gases, and one or more reactant gases are controlled by mass flow controllers 1236 and on-off valves 1238, such as manual diaphragm valves or pneumatic valves. The flow controllers 1236 and valves 1238 may be controlled manually or electronically by a control system.

[0102] Illustrated in FIG. 12, one or more SALD heads 1202 deliver a precursor, reactant, and inert gas onto a flexible substrate material 1224. The head 1202 comprises multiple internal gaschannels that redirect and distribute the gases out onto the flexible material 1224 in an appropriate arrangement to result in SALD, as illustrated in FIG. 11. The head 1202 includes any suitable number and configuration of slits 1250 to output gas to the flexible substrate material 1224. Other components may be integrated into one or more SALD heads 1202, including, but not limited to, cooling and heating elements and plasma sources. For example, one or more plasma sources may be embedded into the head to lower the temperature required for the coating deposition. According to FIG. 12, one or more exhaust pumps 1242 are connected to the head 1202. The exhaust pump 1242 removes gases such as unreacted precursor and / or reactant and inert gas from the space between the operating surface 1244 of the head 1202 and the surface of the flexible material 1224.

[0103] Illustrated in FIG. 12, the heater 1208 may be used to heat the flexible material 1224 to facilitate chemical reactions on the surface of the flexible material 1224. In the example shown, the heater 1208 spans the length of the head 1202. Various heaters with different heating power and with different shapes and sizes (e.g., a drum heater that the flexible material wraps around) may be provided. Additionally, one or more heaters may be embedded into the head 1202. One or more heaters may also be used to control the position of the surface of the flexible material relative to one or more of the SALD heads 1202, based on the mechanical positioning of the heater(s). One or more of the rollers of the conveyance system 1204 may be heated to control the temperature of the flexible material 1224.

[0104] In other examples, a sheet or multiple sheets of flexible material can be mounted on a translating stage which moves past the head either in a single-direction or in both directions for the coating process. The translating stage may be heated and may be used to control the distance between the surface of the flexible material and the surface of a SALD head 1202.

[0105] More information concerning examples of the gas delivery system, SALD head(s), exhaust pump(s), heater(s), and translating stage can be found in PCT publication WO2021119829.

[0106] It should be recognized that features and aspects of the various examples provided above can be combined into further examples that also fall within the scope of the present disclosure. In addition, the figures are not to scale and may have size and shape exaggerated for illustrativepurposes.

Claims

Claims1. A film comprising: a substrate; and a coating deposited on the substrate; wherein the coating includes a plurality of bilayers, each bilayer including two layers of different materials.

2. The film of claim 1, wherein each of the two layers of different materials comprises: an oxide; a metal oxide; an alkoxide; a metalcone; or an oxynitride.

3. The film of claim 1, wherein each bilayer comprises a layer of aluminum oxide and a layer of zinc oxide.

4. The film of claim 3, wherein a bilayer adjacent the substrate has its layer of aluminum oxide in contact with the substrate.

5. The film of claim 1, wherein at least two bilayers of the plurality of bilayers have uniform thickness.

6. The film of claim 1 , wherein at least two bilayers of the plurality of bilayers have different thickness.

7. The film of claim 1, wherein, in at least one of the bilayers of the plurality of bilayers, the two layers of different materials have uniform thickness.

8. The film of claim 1, wherein, in at least one of the bilayers of the plurality of bilayers, the two layers of different materials have different thickness.

9. The film of claim 1, wherein the plurality of bilayers number between 2 and 12.

10. The film of claim 1, wherein each of the two layers of different materials has a thickness of between about 3 nanometers and about 30 nanometers.

11. The film of claim 1 , wherein the coating has a thickness of between about 20 nanometers and about 100 nanometers.

12. The film of claim 1, wherein a layer of the coating that is in contact with the substrate is thicker than other layers of the coating.

13. The film of claim 1, further comprising: an additional substrate including a base material and an ink layer disposed on the base material; and an adhesive layer adhering the additional substrate to the coating.

14. The film of claim 1, wherein: the substrate comprises a base material and an ink layer; and the coating is deposited on the ink layer.

15. The film of claim 14, further comprising: an additional substrate; and an adhesive layer adhering the additional substrate to the coating.

16. The film of claim 1, wherein: the substrate comprises a base material onto which the coating is deposited; and the packaging film further comprises an ink layer disposed on the coating.

17. The film of claim 16, further comprising: an additional substrate; and an adhesive layer adhering the additional substrate to the ink layer.

18. The film of claim 1, wherein: the substrate comprises a base material and a pre-coat; and the coating is deposited on the pre-coat.

19. The film of claim 18, further comprising a top coat disposed on the coating.

20. The film of claim 1 , wherein the substrate comprises polylactic acid.

21. The film of claim 1, wherein the substrate comprises paper.

22. The film of claim 1 , further comprising lamination.

23. The film of claim 1, wherein the two layers of different materials are formed using a coreactant or oxidant.

24. The film of claim 1 , wherein the film is a food packaging film.

25. A film comprising: a substrate; and a coating deposited on the substrate, the coating including a plurality of bilayers, each bilayer including two layers of different materials; wherein each of the two layers of different materials includes an oxide, a metal oxide, an alkoxide, a metalcone, or an oxynitride; wherein each of the two layers of different materials has a thickness of between about 3 nanometers and about 30 nanometers; andwherein the coating has a thickness of between about 20 nanometers and about 100 nanometers.

26. The film of claim 25, wherein a layer of the coating that is in contact with the substrate is thicker than other layers of the coating.

27. A method of making a film, the method comprising: alternately depositing two layers of different materials onto a substrate to form a bilayer, wherein the bilayer has a thickness on a scale of nanometers; and successively forming a plurality of the bilayers to form a coating on the substrate.

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