Covering window assembly, related articles and methods

Abstract

The present invention relates to a cover window assembly comprising a multilayer film of polymeric and inorganic materials in various articles and related articles and methods, which exhibits high resistance to damage from distortion and impact in articles including display devices, particularly flexible display devices.

Description

[Technical field]

[0001] The present invention relates to a cover window assembly comprising a multilayer film of polymeric and inorganic materials in various articles and related articles and methods. The cover window assembly exhibits high resistance to distortion of articles including display devices, particularly flexible display devices, as well as surface and impact damage. [Background technology]

[0002] Multilayer polymeric films are applied to the surface of an article to protect the article from damage during use. With the popularity of consumer electronics, the use of multilayer polymeric films is becoming more and more desirable. Consumer electronics include mobile phones, PDAs, desktop, laptop and notebook computers, and LCD and plasma televisions.

[0003] Displays used in various electronic devices, such as mobile devices, often have cover windows for protection, such as protection against scratches, fingerprints, impact damage, etc. Such cover windows are optically clear films that are attached to the display substrate using an optically clear adhesive.

[0004] Conventional wisdom in the field of flexible display devices dictates that increasingly stiff cover windows are needed to increase the level of protection for the devices. Such conventional wisdom also dictates that flexible display devices should be relatively soft and flexible. Despite cover windows with increased stiffness and desirable flexibility, display damage remains a significant problem, especially in the field of mobile displays. The emerging field of flexible displays brings even greater concerns, as displays must also be able to be folded in addition to providing protection against scratches, fingerprints, impact damage, etc. Flexible displays require a significant reduction in the thickness and stiffness of the cover window, but also feature bendability / flexibility. In addition, display manufacturers are constantly seeking effective impact-resistant materials that can be used to protect sensitive electronic components underneath the cover window of a display device. There remains a need in the art for new cover windows, especially in the field of flexible displays, and methods to improve protection of display touch screens. Summary of the Invention [Means for solving the problem]

[0005] As used throughout this specification, the following abbreviations shall have the following meanings unless the context clearly indicates otherwise: °C = degrees Celsius, g = grams, nm = nanometers, μm = microns = micrometers, mm = millimeters, sec. = seconds, and min. = minutes. Unless otherwise specified, all amounts are weight percent ("wt %") and all ratios are molar ratios. All numerical ranges are inclusive and combinable in any order, except where it is clear that such numerical ranges are constrained to add up to 100%. Unless otherwise specified, all polymer and oligomer molecular weights are weight average molecular weights ("Mw") in g / mole or Daltons, measured using gel permeation chromatography relative to polystyrene standards.

[0006] The articles "a," "an," and "the" refer to the singular and the plural unless the context clearly dictates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated items. "Curable" refers to any material that can be cured under conditions of use. The terms "film" and "layer" are used interchangeably throughout this specification. A layer can be one layer or multiple layers having the same physical properties but different polymer compositions. The term "(meth)acrylate" refers to any of "methacrylate," "acrylate," and combinations thereof. The term "polymer" refers to a molecule composed of repeating monomer units. The term "copolymer" refers to a polymer composed of two or more different monomers as polymerized units, including terpolymers, tetrapolymers, etc. The polymers and copolymers of the present invention can include organic and / or inorganic additives.

[0007] It will also be understood that, although terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and / or section from another element, component, region, layer, and / or section. Thus, a first element, component, region, layer, and / or section could be referred to as a second element, component, region, layer, and / or section without departing from the teachings of the present disclosure. Similarly, the terms "top" and "bottom" are only relative to each other. It will be appreciated that if an element, component, layer, etc. is inverted, what was "bottom" before inversion will be "top" after inversion, and vice versa. When an element is said to be "on" or "disposed on" another element, it means that it is located above or below the object part, but does not essentially mean that it is located on the upper side of the object part based on the direction of gravity; it can be directly on the other element, or there can be intervening elements in between. In contrast, when an element is said to be "directly on" or "directly disposed on" another element, there are no intervening elements present.

[0008] Furthermore, when an element, component, region, layer, and / or section is said to be "between" two elements, components, regions, layers, and / or sections, it will be understood that it may be the only element, component, region, layer, and / or section between the two elements, components, regions, layers, and / or sections or that there may also be one or more intervening elements, components, regions, layers, and / or sections.

[0009] The terms "flexible", "fold", "foldable", "fold", "flex", "flexible" and "flexible" mean that a material can be bent, folded, flexed, rolled, curved or curved, and are used interchangeably throughout this specification. The terms "inward fold", "inward fold", or "internal fold" refer to a configuration in which the display surfaces of different regions are folded to face each other. The terms "outward fold", "outward fold", or "external fold" refer to a configuration in which the display surfaces of different regions are folded to face outward.

[0010] "Transparent layer" refers to a layer that has high light transmittance (typically greater than 90%) across at least a portion of the light spectrum having wavelengths from about 350 to about 1,600 nanometers, including the visible light spectrum (wavelengths from about 380 to about 750 nanometers), and across at least a portion of the surface of the substrate.

[0011] The term "yield stress" is defined in ASTM D638-14. Yield stresses specified in this application are determined according to the method of ASTM D638-14 using an offset value of 0.2%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention provides a cover window assembly comprising one or more multi-layer films of polymeric and / or inorganic materials. The polymeric and / or inorganic layers may comprise an energy dispersing layer, an elastomer layer, a structural layer, a hard coat layer, an oxide layer, or a combination thereof. An adhesive layer may be used between any two layers to enhance the mechanical properties of the cover window assembly. All layers of the cover window assembly are transparent layers.

[0013] The energy dispersion layer may have a modulus of elasticity of more than 0.05 GPa, or more than 0.5 GPa, or more than 2.0 GPa, and a yield stress of less than 110 MPa, or less than 80 MPa, or less than 40 MPa. The thickness of the energy dispersion layer may range from 10 to 400 μm, 25 to 400 μm, or 25 to 350 μm, or 25 to 300 μm, or 25 to 250 μm. The polymeric material that can be used as the energy dispersion layer is not particularly limited as long as the material satisfies the physical properties as described above. Examples of polymeric materials used as the energy dispersion layer may include, but are not limited to, polyimide, polyimide-polyamide, polyamide, polyethersulfone, cyclic olefin copolymer, polyester-imide, polycarbonate, polyester, polyurethane, poly(meth)acrylate, polyurethane-(meth)acrylate, or combinations thereof.

[0014] In one embodiment, the energy dispersing layer may include (a) one or more urethane (meth)acrylate oligomers, (b) one or more mono- or di-(meth)acrylates, (c) one or more (meth)acrylate crosslinkers having three or more (meth)acrylate moieties, and (d) one or more photoinitiators. The energy dispersing layer may then be obtained from polymerizing and curing the composition. Such compositions and the resulting energy dispersing layer are disclosed in U.S. Patent Application Serial No. 16 / 909,067, the entire contents of which are incorporated herein by reference.

[0015] The elastomer layer may have a modulus of elasticity of 1 to 50 MPa, or 1 to 30 MPa, or 1 to 20 MPa, or 1 to 10 MPa, and a Poisson's ratio of at least 0.4, or at least 0.46, or at least 0.48. The elastomer layer may have a thickness of 1 to 600 μm, or 3 to 600 μm, or 5 to 600 μm, or 10 to 600 μm, or 15 to 600 μm, or 20 to 600 μm, or 25 to 600 μm, or 25 to 550 μm, or 25 to 500 μm, or 25 to 450 μm, or 25 to 400 μm. The polymer material that can be used as the elastomer layer is not particularly limited as long as the material satisfies the above physical properties. Examples of polymeric materials used as the elastomeric layer may include, but are not limited to, silicone, polyurethane, polyurethane acrylate, styrene butadiene rubber (SBR), ethylene vinyl acetate (EVA) polymer, polyether block amide (PEBA), polyacrylic acid, fluorosilicone, polyvinyl alcohol, polyetherimide, polystyrene, polyvinyl acetate, polycarbonate-urethane (meth)acrylate (PCUA), or combinations thereof.

[0016] The structural layer may have a modulus of elasticity of at least 3 GPa, or at least 4 GPa, or at least 6 GPa. The structural layer may have a thickness of 10 to 150 μm, or 10 to 120 μm, or 10 to 100 μm, or 20 to 80 μm, or 25 to 80 μm, or 30 to 70 μm, or 40 to 60 μm. The polymeric material that can be used as the structural layer is not particularly limited as long as the material satisfies the physical properties as described above. Examples of polymeric materials used as the structural layer may include, but are not limited to, polyimide, polyimide-polyamide, polyamide, polyethersulfone, polyethylene terephthalate (PET), polyetherketone, cyclic olefin copolymer, polyesterimide, polycarbonate, polymethyl methacrylate, or combinations thereof.

[0017] In one embodiment, the structural layer can be a polyimide film. The polyimide film can be made by polymerizing a dianhydride and a diamine in a solvent to obtain a polyamic acid solution, imidizing the polyamic acid solution to form a substantially imidized solution, and casting the imidized solution. The dianhydride can be selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, alicyclic dianhydrides, and combinations thereof. The diamine can be a fluorinated aromatic diamine such as 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB). The diamine may be an aliphatic amine selected from the group consisting of 1,2-diaminoethane, 1,6-diaminohexane, 1,4-diaminobutane, 1,5-diaminopentane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,16-hexadecamethylenediamine, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, isophoronediamine, bicyclo[2.2.2]octane-1,4-diamine, and combinations thereof. Polyimide films and preparations are disclosed in U.S. Patent Application Serial No. 16 / 912,654, the entire contents of which are incorporated herein by reference.

[0018] In another embodiment, the structural layer can be a polyamide-imide film. The polyamide-imide film includes a copolymer derived from an aromatic dianhydride, an aromatic diamine, and an aromatic dicarbonyl compound. The aromatic dianhydride can be selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), cyclopentanetetracarboxylic dianhydride (CPDA), and combinations thereof. The aromatic diamine can be a fluorinated aromatic diamine such as 2,2'-bis(trifluoromethyl)-1,1'-biphenyl-4,4'-diamine (TFDB). The aromatic dicarbonyl compound can be selected from the group consisting of p-terephthaloyl chloride (TPC), terephthalic acid, isophthaloyl dichloride, and 4,4' benzoyl chloride. Polyamide-imide films and formulations are disclosed in US Pat. Nos. 9,018,343 and 9,580,555, the entire contents of which are incorporated herein by reference.

[0019] The hard coat layer can be made of organic materials, inorganic materials, organic / inorganic hybrid materials, or combinations thereof. Examples of organic materials can include, but are not limited to, epoxy-siloxane resins, silicones, poly(meth)acrylates, polyurethane-(meth)acrylates, polyurethanes, epoxies, and combinations thereof. Inorganic materials can include, but are not limited to, silica, alumina, or zirconia. The organic / inorganic hybrid material can be polysilsesquioxane.

[0020] In one embodiment, the hardcoat layer can be made from a hardcoat composition comprising an epoxy-siloxane oligomer, organic particles having an average diameter of 50-250 nm, and a reactive carrier having one or more epoxy or oxetane moieties. The composition and resulting hardcoat layer are disclosed in U.S. Patent Application Publication No. 2019 / 0185710, the entire contents of which are incorporated herein by reference.

[0021] In another embodiment, the hardcoat layer can be made of a siloxane oligomer or a hardcoat composition comprising a siloxane oligomer with silica or metal oxide nanoparticles. Compositions and hardcoat layers are disclosed in U.S. Patent Application Publication No. 2017 / 0369654 and U.S. Patent Application Publication No. 2019 / 0185633, the entire contents of which are incorporated herein by reference.

[0022] In yet another embodiment, the hardcoat layer may comprise a polyurethane-(meth)acrylate made from a UV-curable acrylic composition. The composition may comprise an aliphatic tri-, tetra-, or penta-functional (meth)acrylate monomer, an acrylate monomer containing an isocyanurate group, a urethane (meth)acrylate oligomer, and a UV radical initiator. The composition and hardcoat layer are disclosed in U.S. Patent Application Publication No. 2019 / 0185602, the entire contents of which are incorporated herein by reference.

[0023] In some embodiments, one hard coat layer may include at least two hard coat layers. The hard coat layer may have a thickness of 0.1 to 200 μm, or 0.5 to 150 μm, or 1 to 100 μm, or 1 to 50 μm, or 1 to 30 μm, or 1 to 20 μm, or 1 to 10 μm, or 1 to 6 μm, or 2 to 50 μm, or 3 to 50 μm, or 3 to 30 μm, or 3 to 15 μm, or 5 to 50 μm, or 5 to 25 μm, or 10 to 50 μm, or 10 to 35 μm, or 15 to 50 μm, or 15 to 30 μm.

[0024] The hard coat layer may have a high modulus and hardness. The hard coat layer may have a pencil hardness of at least 2H, or at least 3H, or at least 4H, or at least 5H, or at least 6H, or at least 7H, or at least 8H, or at least 9H. The pencil hardness is measured with the hard coat layer disposed on glass. The hard coat layer has a nanoindentation modulus of at least 3 GPa, or at least 4 GPa, or at least 8 GPa.

[0025] The oxide layer may be a semiconducting inorganic compound including silicon oxide, silicon oxycarbide, silicon nitride, silicon carbide, aluminum oxide, indium tin oxide, indium doped zinc oxide, zinc oxide, indium oxide, tin oxide, aluminum doped zinc oxide, magnesium-indium oxide, nickel-tungsten oxide, titanium dioxide, tantalum oxide, niobium oxide, molybdenum oxide, iron oxide, chromium oxide, indium gallium oxide, gallium indium zinc oxide, carbon, or combinations thereof. The oxide layer may have a thickness of at least 0.1 μm, at least 0.2 μm, or at least 0.5 μm, or at least 1.0 μm.

[0026] The adhesive layer may include optically clear adhesives (OCA), optically clear resins (OCR), pressure sensitive adhesives (PSA), and the like. The adhesive layer can be formed into a film-like shape that can be bonded using heat or compression processes using silicone, silicone-(meth)acrylate, silicone-epoxy, polyurethane-(meth)acrylate, poly(meth)acrylate, ethylene vinyl acetate (EVA), polydimethylsiloxane (PDMS), polyurethane (PU), vinyl ether polymer, epoxy, and the like. However, the adhesive layer is not limited thereto. The adhesive layer can be formed of a single material or two or more materials. In one embodiment, the adhesive layer has a glass transition temperature (T) below -30°C or above 80°C. gIn some embodiments, the adhesive layer may be replaced by an elastomeric layer between the layers of the cover window assembly of the present invention. The thickness of the adhesive layer may vary from 1 to 200 μm, or 1 to 100 μm, or 1 to 50 μm, or 3 to 50 μm, or 5 to 50 μm, or 5 to 40 μm, or 5 to 30 μm, or 10 to 30 μm.

[0027] Optionally, a primer coating composition or primer layer can be applied to any or some layers in the covering window assembly of the present invention. The primer layer can include polyurethane-acrylate, polyurethane, maleimine-resin, acrylamide polymer, vinyl ether polymer, thiol-isocyanate polymer, silicone, or combinations thereof. Examples of commercially available primers can include, but are not limited to, Rhoplex™ 3208 (The Dow Chemical Company), Dynol™ 604 (Evonik Corporation), and combinations thereof. In one embodiment, the polyurethane can be made from a blocked aliphatic isocyanate polymer resin with a polyalcohol. The primer layer can have a thickness of less than 20 μm, or less than 15 μm, or less than 10 μm, or less than 5 μm, or less than 3 μm, or less than 1 μm.

[0028] The cover window assembly of the present invention may include single or multi-layer films of polymeric and inorganic materials as described above, as well as combinations thereof, based on a unique design to meet the specific requirements of the cover window for display devices. The thickness of each layer of the present invention can be determined based on the specific requirements of the mechanical and optical properties of the cover window assembly. The cover window assembly of the present invention can protect the display device from high-force drop impact while maintaining the optical properties and scratch resistance of the display device. In addition, the cover window assembly is optically transparent and colorless.

[0029] According to the exemplary embodiments described below, a covering window assembly can include a first energy dispersive layer having an upper surface and a lower surface.

[0030] In a first aspect, the covering window assembly may further include a first elastomeric layer. In one embodiment, the first elastomeric layer may be disposed on the top surface of the first energy dispersing layer. A structural layer may be further disposed on the first elastomeric layer. In another embodiment, the first elastomeric layer may be disposed on the bottom surface of the first energy dispersing layer to form a two-layer structure. Such two structures may be stacked together to form another new covering window assembly. Alternatively, the first structural layer may be disposed on the first energy dispersing layer. Furthermore, a second energy dispersing layer may be disposed on the first elastomeric layer. Additionally, a second structural layer may be further disposed on the second energy dispersing layer. In yet another embodiment, the second elastomeric layer may be disposed on the top surface of the first energy dispersing layer of a covering window assembly including a first energy dispersing layer and a first elastomeric layer.

[0031] In a second aspect, the covering window assembly including the first energy dispersing layer may further include a first structural layer disposed on the first energy dispersing layer, the first structural layer having a higher yield stress than the first energy dispersing layer. In one embodiment, the first structural layer may be disposed on the top surface of the first energy dispersing layer to form a two-layer structure. Two such structures may be stacked together to form another new covering window assembly. Furthermore, an elastomer layer may be disposed between the two-layer structure. Alternatively, the first hard coat layer or the first oxide layer may also be disposed on the first structural layer of the two-layer structure. Alternatively, a second energy dispersing layer may be disposed on the structural layer of the two-layer structure.

[0032] In another embodiment, the first structural layer can be disposed on the lower surface of the first energy dispersing layer. A hard coat layer or an oxide layer can be further disposed on the first energy dispersing layer of the cover window assembly. Alternatively, a second structural layer can be disposed on the first energy dispersing layer of the window assembly.

[0033] In a third aspect, the covering window assembly including the first energy dispersive layer may further include a first hard coat layer or a first oxide layer. In one embodiment, the first hard coat layer is disposed on the first energy dispersive layer. In another embodiment, the first oxide layer is disposed on the first energy dispersive layer. In yet another embodiment, the first hard coat layer is disposed on the first energy dispersive layer and the first oxide layer is disposed on the first hard coat layer. In yet another embodiment, the first oxide coat layer is disposed on the first energy dispersive layer and the first hard coat layer is disposed on the first oxide layer.

[0034] In some embodiments, a covering window assembly including a first energy dispersing layer and a first hard coat layer or a first oxide layer may further include a first structural layer disposed on the first hard coat layer or the first oxide layer. A second hard coat layer or a second oxide layer may further be disposed on the first structural layer of the covering window assembly. Furthermore, in one embodiment, a second structural layer may be disposed on the first energy dispersing layer.

[0035] Furthermore, in another embodiment, an adhesive layer can be disposed between the first structural layer and the first hardcoat or first oxide layer in the cover window assembly. Alternatively, the adhesive layer can be disposed on the first energy dispersing layer and then adhered to the second energy dispersing layer. In addition, the second structural layer can be disposed on the second energy dispersing layer. Alternatively, the second structural layer can be disposed between the adhesive layer and the second energy dispersing layer.

[0036] In some embodiments, a covering window assembly including an energy dispersing layer, a structural layer disposed on the energy dispersing layer, and a first hardcoat layer or a first oxide layer disposed on the structural layer may further include, in one embodiment, an elastomer layer disposed on the energy dispersing layer. In another embodiment, the elastomer layer is disposed between the structural layer and the energy dispersing layer. Furthermore, a second hardcoat layer or a second oxide layer may be disposed between the elastomer layer and the energy dispersing layer. Alternatively, the second hardcoat layer or the second oxide layer may be disposed between the elastomer layer and the structural layer. In addition, a third hardcoat layer or a third oxide layer may be further disposed between the elastomer layer and the first energy dispersing layer.

[0037] In one embodiment, a covering window assembly having a first energy dispersive layer, a structural layer disposed on the first energy dispersive layer, and a first hardcoat layer or a first oxide layer disposed on the structural layer, may further include a second hardcoat layer or a second oxide layer disposed on the first energy dispersive layer, and a second energy dispersive layer disposed on the second hardcoat layer or the second oxide layer.

[0038] Many combinations and various arrangements of the energy dispersion layer, structural layer, elastomeric layer, hard coat layer, oxide layer, and adhesive layer can be used to make the covering window assembly of the present invention. For example, the covering window assembly can include (a) an energy dispersion layer, (b) an adhesive layer disposed on the energy dispersion layer, (c) a first hard coat layer or a first oxide layer disposed on the adhesive layer, (d) a structure disposed on the first hard coat layer or the first oxide layer, and (e) a second hard coat layer or a second oxide layer disposed on the structural layer.

[0039] In one embodiment, the covering window assembly may also include (a) an energy dispersive layer; (b) a first hardcoat layer or first oxide layer disposed on the energy dispersive layer; (c) an adhesive layer disposed on the first hardcoat layer or first oxide layer; (d) a second hardcoat layer or second oxide layer disposed on the adhesive layer; (e) a structural layer disposed on the second hardcoat layer or second oxide layer; and (f) a third oxide layer disposed on the structural layer.

[0040] In some embodiments, the covering window assembly may include a set of multilayers attached to the energy dispersing layer by an adhesive layer. In one embodiment, the set of multilayers includes an elastomer layer, a structural layer disposed on the elastomer layer, and a hard coat layer or an oxide layer disposed on the structural layer. In another embodiment, the set of multilayers includes an elastomer layer and a sandwich layer of two hard coat layers or two oxide layers sandwiched with the structural layer disposed on the elastomer layer. In yet another embodiment, the set of multilayers includes an elastomer layer, an energy dispersing layer disposed on the elastomer layer, and a sandwich layer of two hard coat layers or two oxide layers sandwiched with the structural layer disposed on the energy dispersing layer.

[0041] In some embodiments, the covering window assembly may include a set of multilayers adhered to the elastomeric layer by an adhesive layer. In one embodiment, the set of multilayers includes an energy dispersing layer, a structural layer disposed on the energy dispersing layer, and a hard coat layer or oxide layer disposed on the structural layer.

[0042] In some embodiments, the cover window can include a first set of multilayers and a second set of multilayers, with an adhesive layer adhering to the first and second set of multilayers. The first set of multilayers can be a sandwich layer including two hard coat layers or two oxide layers sandwiched by a structural layer. In one embodiment, the second set of multilayers includes an energy dispersing layer and a hard coat layer or oxide layer disposed on the energy dispersing layer. The adhesive layer is disposed between the hard coat layers or oxide layers of the first and second set of multilayers.

[0043] In another embodiment, the second set of multilayers includes an elastomeric layer disposed thereon and an energy dispersing layer disposed on the elastomeric structural layer. In yet another embodiment, the second set of multilayers includes an energy dispersing layer and a structural layer disposed on the energy dispersing layer. In yet another embodiment, the second set of multilayers includes an energy dispersing layer, a structural layer disposed on the energy dispersing layer, and an oxide layer disposed on the structural layer. An adhesive layer is disposed between the hardcoat layer or oxide layer of the first set of multilayers and the oxide layer of the second set of multilayers.

[0044] In some embodiments, the covering window assembly may include a first set of multilayers adhered to a second set of multilayers by an adhesive layer. In one embodiment, the first set of multilayers includes an elastomer layer and a sandwich layer of two hardcoat layers or two oxide layers sandwiched with a structural layer disposed on the elastomer layer, and the second set of multilayers includes an energy dispersing layer and a structural layer disposed on the energy dispersing layer. The adhesive layer is disposed between the elastomer layer of the first set of multilayers and the structural layer of the second set of multilayers. Additionally, a hardcoat layer or oxide layer can be disposed on the structural layer of the second set of multilayers. Alternatively, the second set of multilayers includes an energy dispersing layer and a hardcoat or oxide layer disposed on the energy dispersing layer. The adhesive layer is disposed between the elastomer layer of the first set of multilayers and the hardcoat layer or oxide layer of the second set of multilayers.

[0045] In another embodiment, a first set of multilayers includes a structural layer, a hardcoat layer disposed on the structural layer, and an oxide layer disposed on the hardcoat layer, and a second set of multilayers includes an energy dispersing layer and an elastomeric layer disposed on the energy dispersing layer.

[0046] In some embodiments, the cover window can include a first set of multilayers, a second set of multilayers, and a third set of multilayers, where the first and second set of multilayers are bonded together by a first adhesive layer, and the second and third set of multilayers are bonded together by a second adhesive layer. In one embodiment, the first set of multilayers includes an energy dispersing layer, a hard coat layer or an oxide layer disposed on the energy dispersing layer, the second set of multilayers includes an energy dispersing layer, a hard coat layer or an oxide layer disposed on the energy dispersing layer, and the third set of multilayers includes a sandwich layer of two hard coat layers or two oxide layers sandwiched by a structural layer. An adhesive layer is disposed between the hard coat or oxide layers of the three sets of multilayers.

[0047] At least one primer layer can be optionally included between any two layers of the above cover window assembly.Other layers can also be added to the top of the cover window assembly, including anti-fingerprint coating (AF) layer, anti-reflective coating (AR) layer, and anti-glare coating (AG) layer.The cover window assembly of the present invention has a total thickness of at least 110 μm, or at least 130 μm, or at least 140 μm, or at least 150 μm, or at least 200 μm, or at least 250 μm, or at least 300 μm, or at least 350 μm, or at least 400 μm, or at least 450 μm, or at least 500 μm, or at least 550 μm, or at least 600 μm.

[0048] The interlaminar fracture toughness of any interface of the cover window assembly is at least 100 J / m 2 , or at least 200 J / m 2, or at least 350 J / m 2 The interlaminar fracture toughness can be measured using a double cantilever beam test. In this test, a 1" x 6" multilayer specimen is used. The specimen is bonded top and bottom with 1" x 6" aluminum backings to limit specimen distortion under load and for attachment to a load block. This results in the following sandwich structure: Al backing / "A" ply / "B" ply / "A" ply / Al backing. Load blocks are then attached to the top and bottom aluminum backings. The specimen can be tested on an ElectroForce1000 load frame with a 1000 lb load cell. In this test, an initial crack is intentionally created between the weakest ply and the crack is allowed to propagate along the interface while measuring the lateral load, opening displacement, and crack length along the specimen long axis. If cracks can be readily initiated, the 25 interfacial adhesion is low or moderate and the interlaminar fracture toughness can be measured. If cracks cannot be initiated, the interlaminar adhesion is high or there is no adhesion at all, instead consolidation. A fully compacted 3-ply stack should be inseparable. The location of failure must be elsewhere.

[0049] The cover window assembly of the present invention is transparent and colorless. The optical properties (transmittance, haze, yellowness index, and b*) of the cover window assembly can be measured using a BYK Haze Gard Plus instrument (available from BYK-Gardner GmbH, Germany). The yellowness index can be calculated based on the absorbance spectrum from 395 to 700 nm using a Perkins Elmer Lamba 550-UV spectrometer (available from PerkinElmer Inc., Waltham, Massachusetts). b* (corresponding to the degree of perceived yellowing) can be calculated based on the % transmittance from 380 to 780 nm at a viewing angle of 10 degrees and D65 daylight illumination.

[0050] The covering window assembly may have a haze value of 5% or less, or 3% or less, or 2% or less, or 1% or less. The covering window assembly may have a transmittance of at least 80%, or at least 85%, or at least 90%, or at least 93%, or at least 95%, or at least 98%, or at least 99%. The covering window may have a yellowness index or b* value of less than 1.

[0051] The ball drop test can reveal a wide range of impact damage resistance of the cover window assembly. In the present invention, the ball drop test is used to evaluate the impact resistance of the cover window assembly for protecting 1 mm thick glass. The cover window assembly of the present invention is bonded to 1 mm thick glass using 25 μm OCA for the ball drop test. A 32.7 gram ball with a diameter of about 20 mm can be used for the ball drop test. The height to which the ball is dropped is recorded. The cover window assembly can have a height of at least 10 mm, or at least 20 mm, or at least 50 mm, or at least 100 mm, or at least 150 mm, or at least 200 mm, or at least 250 mm, or at least 300 mm, or at least 350 mm, or at least 400 mm, where the probability of glass breakage is 60%. In one embodiment, the cover window assembly has at least 60% or at least 80% glass survival when subjected to a ball drop test with a 32.7 g stainless steel ball from a height of 10 mm.

[0052] The dart drop test can also reveal a wide range of impact resistance. The test also uses the dart drop test to evaluate the impact resistance of a cover window assembly for protecting 1 mm thick glass. The cover window assembly of the present invention is bonded to 1 mm thick glass using 25 μm OCA for the dart drop test. The dart has a total weight of 5 or 12 grams and a tip diameter of about 1 mm. The cover window assembly can have a height of at least 5 mm, or at least 10 mm, or at least 50 mm, or at least 100 mm, or at least 150 mm, or at least 200 mm, or at least 250 mm, or at least 300 mm, or at least 350 mm, or at least 400 mm, with a 60% probability of glass breakage.

[0053] Pencil hardness testing can reveal a wide range of surface mar resistance. Pencil hardness testing of the cover window assembly is performed according to ASTM DD3363. The cover window assembly can have a standardized pencil hardness of at least 6B, or at least 3B, or at least HB, or at least 1H, or at least 2H, or at least 3H, or at least 4H, or at least 5H, or at least 6H.

[0054] The covering window assembly of the present invention can be made by a variety of processes depending on the particular layers in the covering window assembly. Each individual layer can be formed on a separate substrate by applying a coating composition of the layer onto the substrate, polymerizing and curing the composition under appropriate conditions, and peeling the layer from the substrate. Each individual layer can also be formed by extrusion. The formed layers can be laminated using adhesive and / or elastomeric layers to make the covering window assembly.

[0055] The cover window assembly of the present invention can be applied to various articles, including windshields, displays in electronic devices. In one embodiment, the article can be a flexible display. The cover window assembly can be placed on a flexible display panel or module and can be adhered to the display panel or module by an adhesive layer. The adhesive layer is the same as that described above.

[0056] The cover window assembly can also be made by coextrusion of multiple layers of polymers. Alternatively, the cover window assembly can be made by coating the polymerizable and curable compositions layer by layer onto separate substrates. Alternatively, the cover window can be made using a mixed coating and lamination method.

[0057] The present invention also relates to a display device including the above-mentioned cover window assembly. In one embodiment, the display device is a flexible display device. An exemplary embodiment of the present invention provides a flexible display device including a flexible display module, a lower module, and the above-mentioned cover window assembly. The flexible display module may include a folding region and a peripheral region disposed adjacent to the folding region. The cover window assembly having multiple layers of polymer film overlaps the peripheral region and is easily folded at the folding region of the flexible display device.

[0058] The flexible display device may further include a touch screen and a polarizer between a surface of the flexible display panel and the cover window assembly. EXAMPLES

[0059] Coating Compositions and Film Preparation Polyimide Film - PI

[0060] 12.837 kg of trifluoromethylbenzidine (TFMB, Seika Corporation, Wakayam Seika Kogyo Co., LTD., Japan) and 107.5 kg of dimethylacetamide (DMAC) were charged into a nitrogen-purged 80-gallon reactor with stirring. The solution was stirred to completely dissolve the TFMB in the DMAC solvent and stirring was continued during all subsequent steps. The reaction mixture was heated to about 40°C. 1.11 kg of biphenyltetracarboxylic dianhydride (BPDA, Mitsubishi Chemical Company, Japan) and 15.079 kg of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, Synasia, Metuchen, NJ) were added in four separate aliquots over a period of six hours. Three additional aliquots of 1.831 g of BPDA and 24.881 g of 6FDA were added to the reaction mixture over a period of about three hours. The viscosity of the prepolymer was approximately 89 poise at 25° C. A portion of the polymer was polymerized ("finished") to approximately 1200-1300 poise using a mixture of 6 wt% pyromellitic dianhydride in DMAC in a nitrogen purged reactor. The material was polymerized with a PMDA solution at 40° C. for approximately 24 hours to form a polyamic acid solution.

[0061] The polyamic acid solution was cast onto a moving belt and dried at an oven temperature ranging from about 95 to about 150° C. The free-standing film was peeled off from the belt and dried by heating with a radiant heater in a tenter oven at a temperature (radiant heater surface temperature) of about 110 to about 675° C., thereby imidizing the polymer film. A 50 μm PI film was obtained.

[0062] Polyethylene terephthalate (PET) film - PET 50 μm PET film was obtained from Tekra (Melinex® 462 from DuPont Teijin Films™).

[0063] Optically transparent adhesive film-OCA 25 μm OCA film (3M™ Optically Clear Adhesives 8211) was obtained from APD Inc.

[0064] Hard Coat Liquid Formulation-P1 The formulation was prepared by mixing PC-2000HV (27.5 parts by weight, Polyset Co. Inc.), silica nanoparticles YSE-AY4 (30.5 parts by weight, Admatechs Oc. Ltd.), bis(7-oxabicyclo[4.1.0]heptan-3-ylmethyl)adipate (3 parts by weight, Matrix Scientific), diisopropyl ketone (34.2 parts by weight, Sigma-Aldrich), propylene glycol methyl ether (3.8 parts by weight, Sigma-Aldrich), BYK-307 (0.1 parts by weight, BYK USA Inc.), Tinuvin® 1600 (0.2 parts by weight, BASF), and CPI-310FG (0.6 parts by weight, San Apro Ltd., Japan), followed by filtration (pore size 1.0 μm, Whatman™).

[0065] Hard Coat Liquid Formulation-P2 The formulation was prepared by mixing Ebercryl™ 8602 (45 parts by weight, Allnex), Photomer® 4356 (20 parts by weight, IGM Resins), Sartomer SR399 (15 parts by weight, Arkema), Ebercryl™ LED 02 (15 parts by weight, Allnex), Esacure KTO 46 (5 parts by weight, IGM Resins) in propylene glycol methyl ether acetate (166.67 parts by weight, Sigma-Aldrich). The resulting mixture was filtered (pore size 0.2 μm, Whatman™), then OPTOOL DAC-HP (1 part by weight, Daikin Industries, Ltd.) and NANOBYK-3601 (1 part by weight, BYK USA Inc.) were added, followed by filtration (pore size 1.0 μm, Whatman™). The final formulation concentration range was adjusted to 20–60 wt % solids by further dilution with either propylene glycol methyl ether acetate (Sigma-Aldrich), methyl isobutyl ketone (Sigma-Aldrich), or 2-pentanone (Sigma-Aldrich).

[0066] Urethane acrylate liquid formulation-E5 The formulation was prepared by mixing 39.7 g of Ebecryl™ 230 with 39.7 g of Ebecryl™ 130 (available from Allnex), 2.5 g of Omnirad™ 4265, 1.3 g of Omnirad™ 819, and 1.3 g of Omnirad™ 184 (available from IGM Resin), 4.2 g of trimethylolpropane triacrylate (TMPTA), 4.2 g of Jeffamine® T403 (available from Huntsman), 7.1 g of methyl isobutyl ketone (MIBK), and 0.2 g of Omnistab IC (available from IGM Resin) to obtain a homogenous liquid formulation.

[0067] 2. Preparation of Cover Window Assembly Example 1 P2 was coated onto 50 μm PET film on a nRad slot die coater (nTact) using a shim thickness of 2 mils at a coating speed of approximately 30 mm / sec and a coating flow rate of 30-200 uL / sec. The coating was then solvent removed at 90 °C, and the dried film was subsequently cured using a belt speed of approximately 50 ft / min in a Fusion F300S UV curing system (Heraeus Noblelight America LLC) equipped with D bulb lamps. Multiple passes under the UV curing system were used to produce a 2,000-4,500 mJ / cm2 coating. 2 A UV dosage of 100 μm was reached, resulting in a bilayer structure with a 5 μm P2 film on a 50 μm PET film, designated P2(5 μm) / PET(50 μm). Two of the bilayer P2(5 μm) / PET(50 μm) layers were then laminated using a 25 μm OCA film through a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F., resulting in a multilayer structure designated P2(5 μm) / PET(50 μm) / OCA(25 μm) / P2(5 μm) / PET(50 μm).

[0068] Example 2 50 μm E5 films were prepared by casting the liquid formulation E5 prepared above onto a PET substrate on a nRad slot die coater at a coating speed of approximately 2 mm / sec and a coating flow rate of 30-200 uL / sec using a shim thickness of 4 mils. The formulation solvent was removed using a soft bake process at 90°C. The cast films were cured and solidified using a Fusion UV curing system (F300S) equipped with a D bulb (radiant energy output of 100-440 nm). The belt / line speed of the UV conveyor was set at approximately 50 ft / min. Multiple passes on the UV conveyor were used to achieve sufficient curing at 2,000-4,500 mJ / cm. 2The UV dose reached 1000 μm. The cured film was then baked at 90° C. for 15 min to remove residual solvent and unreacted monomer. The film was then peeled off from the PET substrate to obtain a 50 μm E5 film.

[0069] The bilayer structure P2(5 μm) / PET(50 μm) was prepared as described in Example 1. The bilayer structure of 5 μm P2 film on 50 μm E5 film was prepared using the same procedure as described in Example 1, except that the PET film was replaced with E5 film, and is designated as P2(5 μm) / PET(50 μm). The bilayer structure P2(5 μm) / PET(50 μm) was then laminated with a 25 μm OCA film on top of the P2 film of the bilayer structure P2(5 μm) / E5(50 μm) through a laminator model Catena 35 (GBC) with a copper-coated board support, using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F., to obtain a multilayer structure designated as P2(5 μm) / PET(50 μm) / OCA(25 μm) / P2(5 μm) / E5(50 μm).

[0070] Example 3 The bilayer structures P2(5 μm) / PET(50 μm) and P2(5 μm) / E5(50 μm) were prepared using the same procedures as described in Examples 1 and 2, respectively. The lamination procedure was the same as in Example 2, except that the bilayer structure P2(5 μm) / E5(50 μm) was laminated on top of the P2 film of the bilayer structure P2(5 μm) / PET(50 μm), resulting in a multilayer structure indicated as P2(5 μm) / E5(50 μm) / OCA(25 μm) / P2(5 μm) / PET(50 μm).

[0071] Example 4 Two sets of bilayer structures of 5 μm P2 film on 50 μm PI film were prepared using the same procedure as described in Example 1, except that the PET film was replaced with the PI film, and are designated as P2(5 μm) / PI(50 μm). The two sets of bilayer structures P2(5 μm) / PI(50 μm) were then laminated using a 25 μm OCA film through a laminator model Catena 35 (GBC) with a copper-coated board support, using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F., to obtain a multilayer structure designated as P2(5 μm) / PI(50 μm) / OCA(25 μm) / P2(5 μm) / PI(50 μm).

[0072] Example 5 The bilayer structure P2(5 μm) / PI(50 μm) was prepared as described in Example 4, and the bilayer structure P2(5 μm) / E5(50 μm) was prepared as described in Example 2. The bilayer structure P2(5 μm) / PI(50 μm) was laminated on top of the P2 film of the bilayer structure P2(5 μm) / E5(50 μm) using a 25 μm OCA film through a laminator model Catena 35 (GBC) with a copper-coated board support, using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F., to obtain a multilayer structure shown as P2(5 μm) / PI(50 μm) / OCA(25 μm) / P2(5 μm) / E5(50 μm).

[0073] Example 6 The bilayer structures P2(5 μm) / E5(50 μm) and P2(5 μm) / PI(50 μm) were prepared using the same procedures as described in Examples 2 and 4, respectively. The lamination procedure was the same as in Example 5, except that the bilayer structure P2(5 μm) / E5(50 μm) was laminated on top of the P2 film of the bilayer structure P2(5 μm) / PI(50 μm), resulting in a multilayer structure indicated as P2(5 μm) / E5(50 μm) / OCA(25 μm) / P2(5 μm) / PI(50 μm).

[0074] Example 7 The bilayer construct E5(50 μm) / PET(50 μm) was prepared based on the procedure described in Example 1, except that the P2 liquid formulation was replaced with the E5 liquid formulation.

[0075] A bilayer structure P2(5 μm) / PET(50 μm) was prepared as described in Example 1. The P1 liquid formulation was coated onto the PET film of the bilayer structure P2(5 μm) / PET(50 μm) using the same procedure as described in Example 1, except that the P2 liquid formulation was replaced with the P1 liquid formulation, to obtain 10 μm of P1 on top of the PET film of the bilayer structure P2(5 μm) / PET(50 μm), forming a three-layer structure shown as P2(5 μm) / PET(50 μm) / P1(10 μm). The E5 liquid formulation was coated onto the 10 μm P1 film of the three-layer structure using the same coating procedure as described in Example 1, to form a 50 μm E5 film on top of the 10 μm P1 film. As a result, a four-layer structure was formed, designated as P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm).

[0076] The PET film in the two-layer structure E5(50 μm) / PET(50 μm) was then laminated with the E5 film in the four-layer structure P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) using a 25 μm OCA film via a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a multilayer structure shown as P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / PET(50 μm) / E5(50 μm).

[0077] Example 8 A 100 μm film of E5 was prepared using the same procedure described in Example 2, except that twice the amount of liquid formulation E5 was cast.

[0078] A 50 μm E5 film was prepared as described in Example 2. A 50 μm E5 film was used to prepare a four-layer structure P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) as described in Example 7.

[0079] The 100 μm E5 film was then laminated with the 25 μm OCA film through a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a four-layer structure shown as P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / E5(100 μm).

[0080] Example 9 The four-layer structure P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) and the two-layer structure E5(50 μm) / PET(50 μm) were prepared as described in Example 7.

[0081] The E5 film in the two-layer structure E5(50 μm) / PET(50 μm) was then laminated with the E5 film in the four-layer structure P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) using a 25 μm OCA film via a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a multilayer structure shown as P2(5 μm) / PET(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / E5(50 μm) / PET(50 μm).

[0082] Example 10 A four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) was prepared as described in Example 7, except that the 50 μm PET film was replaced with a 50 μm PI film. A two-layer structure E5(50 μm) / PI(50 μm) was prepared as described in Example 7, except that the 50 μm PET film was replaced with a 50 μm PI film.

[0083] The PI film in the two-layer structure E5(50 μm) / PI(50 μm) was then laminated with the E5 film in the four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) using a 25 μm OCA film via a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a multilayer structure shown as P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / PI(50 μm) / E5(50 μm).

[0084] Example 11 A four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) was prepared as described in Example 10.

[0085] A 100 μm E5 film was prepared as described in Example 8.

[0086] The 100 μm E5 film was then laminated with the E5 film in a four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) using the 25 μm OCA film through a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a multilayer structure shown as P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / E5(100 μm).

[0087] Example 12 A four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) was prepared as described in Example 7, and a two-layer structure E5(50 μm) / PI(50 μm) was prepared as described in Example 10.

[0088] The 50 μm E5 film in the two-layer structure E5(50 μm) / PI(50 μm) was then laminated with the E5 film in the four-layer structure P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) using a 25 μm OCA film via a laminator model Catena 35 (GBC) with a copper coated board support using a lamination gap of 3 mm, a roll speed setting of 5, and a lamination temperature of 90° F. to obtain a multilayer structure shown as P2(5 μm) / PI(50 μm) / P1(10 μm) / E5(50 μm) / OCA(25 μm) / E5(50 μm) / PI(50 μm).

[0089] Cover window assembly mechanical properties Ball Drop Test Method - Ball drop tests were conducted to evaluate the impact resistance of the cover window assembly for protecting 1 mm thick glass. Samples of the cover window assembly were bonded to 1 mm thick microslide glass (1 inch x 3 inches) using 25 μm OCA film to form a test stack. The test stack was placed on a 3 inch thick polished granite. To evaluate the effectiveness of the cover window for protecting 1 mm thick glass, a 32.7 gram stainless steel ball with a diameter of about 20 mm was dropped from various heights. The impact performance of glass is highly dependent on the size of the flaw and the distribution of the flaws. Therefore, to develop the failure probability at various heights, 20 drops were performed at each height and the 60% failure rate was recorded as the characteristic failure of each test stack for comparison. Table 1 shows the 60% failure height of the glass, where the stacks have the cover window assemblies, adhesive film and glass of Examples 1-12.

[0090] [Table 1] The present invention includes the following embodiments. A cover window assembly comprising a first energy dispersing layer having an elastic modulus greater than 1.0.05 GPa and a yield stress less than 110 MPa. 2. The covering window assembly of claim 1, further comprising an elastomeric layer having a modulus of elasticity of at least 1 MPa and a Poisson's ratio of at least 0.4, the elastomeric layer being disposed on an upper or lower surface of the first energy dispersing layer. 3. The cover window assembly of claim 1, further comprising a first structural layer having a yield stress higher than the yield stress of the first energy dispersive layer and a modulus of elasticity of at least 3 GPa, the first structural layer being disposed on an upper or lower surface of the first energy dispersive layer. 4. The cover window assembly of claim 1, further comprising a first hardcoat layer or a first oxide layer disposed on an upper or lower surface of the first energy dispersing layer. 5. The cover window assembly of claim 4, further comprising a first structural layer having a yield stress higher than the yield stress of the first energy dispersive layer and an elastic modulus of at least 3 GPa and disposed on the first hard coat layer or the first oxide layer. 6. The cover window assembly of claim 5, further comprising a second hardcoat layer or a second oxide layer disposed on the first structural layer. 7. The cover window assembly of claim 3, further comprising a first hardcoat layer or a first oxide layer disposed on the first structural layer. 8. The cover window assembly of claim 3, further comprising a hard coat layer or an oxide layer disposed on the first energy dispersing layer. 9. The cover window assembly of claim 6, further comprising an adhesive layer disposed between the first structural layer and the first hardcoat layer or the first oxide layer. 10. The cover window assembly of claim 4, further comprising an adhesive layer disposed on the first energy dispersing layer, a second hard coat layer or a second oxide layer disposed on the adhesive layer, and a structural layer having a yield stress higher than the yield stress of the first energy dispersing layer and a modulus of elasticity of at least 3 GPa and disposed on the second hard coat layer or the second oxide layer. 11. The covering window assembly of claim 6, further comprising an adhesive layer disposed on the first energy dispersion layer, and a second energy dispersion layer having a modulus of elasticity greater than 0.05 Gpa and a yield stress less than 110 MPa and disposed on the adhesive layer. 12. The cover window assembly of claim 11, further comprising a second structural layer having a yield stress higher than the yield stress of the second energy dispersing layer and a modulus of elasticity of at least 3 GPa, the second structural layer being disposed between the adhesive layer and the second energy dispersing layer. 13. The covering window assembly of claim 11, further comprising a second structural layer disposed on the second energy dispersing layer, the second structural layer having a yield stress higher than the yield stress of the second energy dispersing layer and a modulus of elasticity of at least 3 GPa. 14. The cover window assembly of claim 6, further comprising a second structural layer disposed on the first energy dispersing layer, the second structural layer having a yield stress higher than the yield stress of the first energy dispersing layer and a modulus of elasticity of at least 3 GPa. 15. The cover window assembly of claim 7, further comprising a second hard coat layer or a second oxide layer disposed on the first energy dispersive layer, and a second energy dispersive layer having an elastic modulus greater than 0.05 Gpa and a yield stress less than 110 MPa and disposed on the second hard coat layer or the second oxide layer. 16. The cover window assembly of claim 7, further comprising an elastomeric layer having a modulus of elasticity of at least 1 MPa and a Poisson's ratio of at least 0.4, the elastomeric layer being disposed on the first energy dispersing layer. 17. A cover window assembly according to any one of 2 to 16, wherein the cover window comprises at least one primer layer between the two layers. 18. A cover window assembly comprising: (a) an energy dispersion layer; (b) an adhesive layer disposed on the energy dispersion layer; (c) a first hardcoat layer or a first oxide layer disposed on the adhesive layer; (d) a structure disposed on the first hardcoat layer or the first oxide layer; and (e) a second hardcoat layer or a second oxide layer disposed on the structure layer. 19. A cover window assembly comprising: (a) an energy dispersive layer; (b) a first hardcoat layer or a first oxide layer disposed on the energy dispersive layer; (c) an adhesive layer disposed on the first hardcoat layer or the first oxide layer; (d) a second hardcoat layer or a second oxide layer disposed on the adhesive layer; (e) a structural layer disposed on the second hardcoat layer or the second oxide layer; and (f) a third oxide layer disposed on the structural layer. 20. A display device comprising an upper module including a cover window assembly according to any one of 1 to 19, a display module, and a lower module.

Claims

1. A thermal expansion coefficient measuring device comprising: a first energy dispersing layer having an elastic modulus greater than 0.05 GPa and a yield stress less than 110 MPa; further comprising a first hard coat layer or a first oxide layer disposed on an upper surface or a lower surface of the first energy dispersing layer; a first structural layer having a yield stress higher than the yield stress of the first energy dispersive layer and an elastic modulus of at least 3 GPa, the first structural layer being disposed on the first hardcoat layer or the first oxide layer; 13. A covering window assembly, wherein the first energy dispersing layer is selected from the group consisting of polyimide, polyimide-polyamide, polyamide, polyethersulfone, cyclic olefin copolymer, polyester-imide, polycarbonate, polyester, polyurethane, poly(meth)acrylate, polyurethane-(meth)acrylate, or combinations thereof.

2. 10. The cover window assembly of claim 1, further comprising a second hardcoat layer or a second oxide layer disposed on the first structural layer.

3. 3. The cover window assembly of claim 2, further comprising an adhesive layer disposed between the first structural layer and the first hardcoat layer or the first oxide layer.

4. A thermal expansion coefficient measuring device comprising: a first energy dispersing layer having an elastic modulus greater than 0.05 GPa and a yield stress less than 110 MPa; further comprising a first hard coat layer or a first oxide layer disposed on an upper surface or a lower surface of the first energy dispersing layer; an adhesive layer disposed on the first energy dispersing layer; a second hard coat layer or a second oxide layer disposed on the adhesive layer; and a structural layer disposed on the second hard coat layer or the second oxide layer, the structural layer having a yield stress higher than the yield stress of the first energy dispersing layer and an elastic modulus of at least 3 GPa; 13. A covering window assembly, wherein the first energy dispersing layer is selected from the group consisting of polyimide, polyimide-polyamide, polyamide, polyethersulfone, cyclic olefin copolymer, polyester-imide, polycarbonate, polyester, polyurethane, poly(meth)acrylate, polyurethane-(meth)acrylate, or combinations thereof.

5. 3. The covering window assembly of claim 2, further comprising an adhesive layer disposed on the first energy dispersing layer, and a second energy dispersing layer having a modulus of elasticity greater than 0.05 Gpa and a yield stress less than 110 MPa and disposed on the adhesive layer.

6. 6. The covering window assembly of claim 5, further comprising a second structural layer having a yield stress higher than the yield stress of the second energy dispersing layer and a modulus of elasticity of at least 3 GPa, the second structural layer being disposed between the adhesive layer and the second energy dispersing layer.

7. 6. The covering window assembly of claim 5, further comprising a second structural layer disposed on the second energy dispersing layer, the second structural layer having a yield stress higher than the yield stress of the second energy dispersing layer and a modulus of elasticity of at least 3 GPa.

8. 3. The covering window assembly of claim 2, further comprising a second structural layer disposed on the first energy dispersing layer, the second structural layer having a yield stress higher than the yield stress of the first energy dispersing layer and a modulus of elasticity of at least 3 GPa.

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