Patent ID: 12241007

DETAILED DESCRIPTION

The following examples are illustrative, but not limiting, of the present disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the art, are within the spirit and scope of the disclosure.

Cover substrates for consumer products, for example cover glass, may serve to, among other things, reduce undesired reflections, prevent formation of mechanical defects in the glass (e.g., scratches or cracks), and/or provide an easy to clean transparent surface. The articles disclosed herein may be incorporated into another article, for example, an article with a display (or display articles) (e.g., consumer electronic products, including mobile phones, tablets, computers, navigation systems, wearable devices (e.g., watches) and the like), architectural articles, transportation articles (e.g., automotive, trains, aircraft, sea craft, etc.), appliance articles, or any article that may benefit from some transparency, scratch-resistance, abrasion resistance, or a combination thereof. An exemplary article incorporating any of the glass articles disclosed herein is a consumer electronic device including a housing having front, back, and side surfaces; electrical components that are at least partially inside or entirely within the housing and including at least a controller, a memory, and a display at or adjacent to the front surface of the housing; and a cover substrate at or over the front surface of the housing such that it is over the display. In some embodiments, at least a portion of the housing comprises a glass article as disclosed herein.

Cover substrates, for example cover glasses, also serve to protect sensitive components of a consumer product from mechanical damage (e.g., puncture and impact forces). For consumer products including a flexible, foldable, and/or sharply curved portion (e.g., a flexible, foldable, and/or sharply curved display screen), a cover substrate for protecting the display screen should preserve the flexibility, foldability, and/or curvature of the screen while also protecting the screen. Moreover, the cover substrate should resist mechanical damage, for example scratches and fracturing, so that a user can enjoy an unobstructed view of the display screen.

Thick monolithic glass substrates may provide adequate mechanical properties, but these substrates can be bulky and incapable of folding to tight radii in order to be utilized in foldable, flexible, or sharply curved consumer products. And highly flexible cover substrates, such a plastic substrate, may be unable to provide adequate puncture resistance, scratch resistance, and/or fracture resistance desirable for consumer products.

The present application discloses bendable and/or flexible articles that take advantage of the characteristics of thin glass substrates and that also have suitable mechanical properties to resist failure during use. Impact resistance and the ability to bend without failure are desirable design parameters for foldable and/or bendable devices.

With respect to impact resistance, an article can occasionally experience extreme impact loading events. These events can include, for example, an external object impact (e.g., a pen impact) and an article drop. A foldable and/or bendable article should be able to withstand common impact events like these without failure.

With respect to bending, an article should not fail under the bending conditions for which the article was designed and during its normal and intended use. In some cases, these bending conditions may include bending of the article to very small bending radii. However, at the same time, the bend force to bend the article to the intended bending radii should also be small enough such that an average person can bend the article without difficulty. Relatively low bending forces to fold or otherwise bend an article can be particularly beneficial to a user when the article is employed in applications that include manual bending (e.g., a foldable, wallet-like flexible display device).

The present application discloses adhesive layers that improve impact resistance of an article without negatively affecting the bendability of the article (for example, the ability of an article to bend to a certain bend radius without failure) or significantly increasing the bend force to bend the article to a desired bend radius. More particularly, adhesive layers according to embodiments of the present application have a dynamic elastic modulus that provides desired bendability and impact resistances. At low strain rates (stress frequencies) associated with a bending event the elastic modulus of the adhesive layer is low enough to facilitate bending at low bend forces without device or cover glass failure. At high strain rates (stress frequencies) associated with an impact even (e.g., pen impact or device drop), the elastic modulus of the adhesive layer is high enough to prevent device or cover glass failure.

As disclosed herein, the bendability of a foldable article can be preserved and high impact resistance for the foldable article can be achieved using an adhesive layer with an appropriate dynamic elastic modulus. This dynamic elastic modulus allows the adhesive layers to provide desired bendability and impact resistance for articles discussed herein. During a bending event, the stress loading speed is in a relatively low frequency range. So, if the elastic modulus of an adhesive layer is kept relatively low and constant across the low frequency range, the bendability of an article will not be significantly influenced by the adhesive layer. In contrast to a bending event, during an impact event, the stress loading speed is relatively high (e.g., on the order of one tenth of a second or less). So, if the elastic modulus of an adhesive layer is sufficiently high during a high stress loading speed event, the adhesive layer can improve impact resistance. This in turn improves the mechanical reliability of an article.

A “dynamic elastic modulus” means that the elastic modulus of that material is dependent on the rate of strain (stress frequency) applied to the material. Unless stated otherwise, a “dynamic elastic modulus” is measured using a Dynamic Mechanical Analysis (DMA) according to ASTM standards D4065, D4440, and D5279. ASTM 4065 establishes the practice for gathering and reporting the dynamic mechanical data of ASTM 4440 and ASTM 5279. Based on the combined results and procedures of these three standards, the viscoelastic behavior and/or dilatant behavior of a material with respect to frequency of stress application and temperature of the material can be characterized. If an elastic modulus is defined as having a value “in” or “within” a range of Hertz values, only one whole number Hertz value within the range is required to result in the elastic modulus value. If an elastic modulus is defined as having a value “across” a range of Hertz values, the value remains true for each whole number Hertz value within the range. A Hertz frequency value is the reciprocal of the time over which a load or force (e.g., impact) is applied to a material. For example, an impact event can apply an impact force for a fraction of second. As another example, a bending event can apply a bending force for 1-2 seconds.

Unless stated otherwise, elastic moduli are measured at room temperature, which for purposes of the present application is equal to 23 degrees C. Exemplary materials having a “dynamic elastic modulus” include viscoelastic materials and shear thickening materials. Elastic moduli discussed herein may also be referred to as storage moduli.

Among other features and benefits, adhesive layers disclosed herein can be incorporated into an article (e.g., a bendable electronic device or bendable electronic device module) to provide desired mechanical reliability at small bend radii (e.g., in static tension and fatigue) as well as high puncture resistance for the article. Configurations of these articles are also characterized by relatively low bending forces to fold or otherwise bend these articles. With regard to mechanical reliability, the articles are configured to avoid cohesive failures in their cover glass layers and delamination-related failures at interfaces between the various components of the articles (e.g., adhesive-cover glass layer interfaces). The small bend radii and puncture resistance capabilities can be beneficial when the bendable articles are used in, for example, a foldable electronic device display, such as one where one portion of the display is folded over on top of another portion of the display. For example, the articles may be used as one or more of: a cover on the user-facing portion of a foldable electronic display device, a location in which puncture resistance is particularly beneficial, a substrate module, disposed internally within the device itself, on which electronic components are disposed; or elsewhere in a foldable electronic display device. Articles disclosed herein may also be used in a device not having a display, but one in which a cover glass layer is used for its beneficial properties and is folded or otherwise bent, in a similar manner as in a foldable display, to a tight bend radius.

As demonstrated herein, using an adhesive material with a sufficiently high modulus in a high frequency range reduces maximum principle stresses on cover glass surfaces during an impact event. Hence, articles including such an adhesive material bonding a cover glass to a substrate are capable of withstanding relatively high pen drop heights and are capable of demonstrating improved drop performance. This concept is proved herein using dynamic finite element methods that compare simulation results of different adhesive materials. By utilizing an appropriate adhesive material for bonding a cover glass to a substrate, an article can have the following characteristics: good mechanical reliability, high impact resistance, thin stack design, light weight, low manufacturing costs, ease of bending (folding), low force to bend the article, and/or a less complex hinge portion at which the article is designed to bend.

FIG.1illustrates an article100according to some embodiments. Article100includes a substrate110and a cover glass layer120bonded to the substrate110with an adhesive layer130. Cover glass layer120may be disposed over all or a portion of a top surface114of substrate110. Cover glass layer120may cover all or a portion of substrate110. Cover glass layer120may cover all or a portion of top surface114of substrate110. In some embodiments, cover glass layer120may cover the entirety of top surface114. In such embodiments, cover glass layer120may cover top surface114of substrate110between all opposing edges of top surface114. In some embodiments, cover glass layer120may be directly bonded to top surface114of substrate110with adhesive layer130.

In some embodiments, substrate110may be an electronic display or electronic display component including an electronic display. In such embodiments, all or a portion of top surface114of substrate110may be a display surface of the electronic display or electronic display component. In other words, the display surface may define all or a portion of top surface114of substrate110. Exemplary electronic displays include a light emitting diode (LED) display or an organic light emitting diode (OLED) display. In some embodiments, substrate110may be a non-electronic display device. For example, substrate110may be a display device that displays static or printed indicia. In some embodiments, substrate110may be or may include a touch sensor, such as a capacitive touch sensor, a polarizer, or a battery.

In some embodiments, substrate110, for example an electronic display or electronic display component, may be a flexible substrate. As used herein, a flexible cover glass layer120, article100, or substrate110is a layer, article, or substrate characterized by the ability of the cover glass layer1200, article100, or substrate110to avoid failure during a two-point bend test when held between two plates at a plate distance of 20 millimeters (mm) or less for at least 240 hours at about 85° C. and about 85% relative humidity. A plate distance is the linear distance in a straight line between opposing exterior surfaces of a substrate110, article100, or cover glass layer120during a two-point bend test. For example, “D” represents the plate distance for substrate110(and article100) inFIG.2and “d” represents the plate distance for cover glass layer120. InFIG.2, “D” is “d” plus two times the thickness136of adhesive layer130and two times the thickness of substrate110. In some embodiments, substrate110, article100, and/or cover glass layer120may be characterized by the ability of substrate110, article100, and/or cover glass layer120to avoid failure when held between two plates at a plate distance of 20 mm or less, 15 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, or 1.5 mm or less. In some embodiments, cover glass layer120may have a thickness126, measured from bottom surface122to top surface124, in the range of 1 micron (μm, micrometers) to 200 microns, including subranges therebetween. For example, cover glass layer120may have a thickness126of 1 micron, 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 75 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, 125 microns, 130 microns, 140 microns, 150 microns, 160 microns, 170 microns, 175 microns, 180 microns, 190 microns, or 200 microns, or within a range having any two of these values as end points. In some embodiments, cover glass layer120may have a thickness126in the range of 1 micron to 125 microns. In some embodiments, cover glass layer120may have a thickness126in the range of 1 micron to 75 microns.

In some embodiments, cover glass layer120may be an ultra-thin glass layer. As used herein, the term “ultra-thin glass layer” means a glass layer having a thickness126in the range of 0.1 microns to 75 microns. In some embodiments, cover glass layer120may be a strengthened glass layer, such as a glass layer that has been subject to an ion-exchange process or a thermal tempering process. For a cover glass layer120subject to an ion-exchange process, the cover glass layer120includes a compressive stress at top surface124and/or bottom surface122and a concentration of metal oxide that is different at two or more points through thickness126of cover glass layer120. In some embodiments, cover glass layer120may be a non-strengthened glass layer, such as a glass layer that has not been subject to an ion-exchange process or a thermal tempering process.

In some embodiments, cover glass layer120may be an optically transparent glass layer. As used herein, “optically transparent” means an average transmittance of 70% or more in the wavelength range of 400 nm to 700 nm through a 1.0 mm thick piece of a material. In some embodiments, an optically transparent material may have an average transmittance of 75% or more, 80% or more, 85% or more, or 90% or more in the wavelength range of 400 nm to 700 nm through a 1.0 mm thick piece of the material. The average transmittance in the wavelength range of 400 nm to 700 nm is calculated by measuring the transmittance of all whole number wavelengths from 400 nm to 700 nm and averaging the measurements.

In some embodiments, cover glass layer120may include an alkali-containing aluminosilicate glass material. Other suitable materials for cover glass layer120include amorphous materials, such as but not limited to, soda lime glass, alkali-containing borosilicate glass, and alkali aluminoborosilicate glass. In some variants, the glass material may be free of lithia.

In some embodiments, cover glass layer120may be a redrawn glass layer. In some embodiments, cover glass layer120may be a glass layer formed using a process devoid of a chemical thinning process (for example, cover glass layer120may be a non-chemically thinned glass layer, or may be a non-thinned glass layer). As used herein, the term “redrawn cover glass layer” means a layer of glass material that was drawn to its final thickness in a redrawing process. For example, in a redrawing process, a glass block may be heated to a desired drawing temperature and stretched by draw rollers to reduce its thickness to the final thickness of a cover glass layer. After redrawing to the final thickness, no additional process steps are utilized to significantly change the thickness of the cover glass layer. Grinding or polishing may be used to shape the edges of a redrawn cover glass layer, but such grinding or polishing is not considered as changing the thickness of the layer. As used herein, the term “chemically thinned cover glass layer” means a layer of glass material that was subjected to one or more chemical etching processes to reduce its thickness to the final desired thickness of the glass layer. A chemically thinned (also called etched) glass layer will have different properties than a redrawn glass layer due to the etching process(es) used to reduce its thickness. For example, surfaces of a redrawn glass layer may be significantly smoother than surfaces of a chemically thinned glass layer. The surface roughness for redrawn glass layer can be as small as about 0.1 nm (nanometers)-0.2 nm while the minimum surface roughness of a chemically thinned glass layer is about 2 nm-3 nm.

In some embodiments, cover glass layer120may be a single monolithic layer. As used herein, “single monolithic layer” means a single integrally formed layer having a generally consistent composition across its volume. A layer that is made by layering one or more layers or materials, or by mechanically attaching different layers, is not considered a single monolithic layer. In some embodiments, cover glass layer120may be a multi-layer glass.

In some embodiments, top surface124of cover glass layer120may be a topmost exterior, user-facing surface of article100. As used herein, the terms “top surface” or “topmost surface” and “bottom surface” or “bottommost surface” reference the top and bottom surface of a layer, component, or article as is would be oriented during its normal and intended use with the top surface being the user-facing surface. For example, when incorporated into a hand-held consumer electronic product having an electronic display, the “top surface” of an article or layer refers to the top surface of that article or layer as it would be oriented when held by a user viewing the electronic display through the article or layer.

In some embodiments, top surface124of cover glass layer120may be coated with one or more coating layers (e.g., a coating layer150) to provide desired characteristics. Such coating layers include, but are not limited to, polymeric hard-coating layers, anti-reflection coating layers, anti-glare coating layers, anti-fingerprint coating layers, anti-microbial and/or anti-viral coating layers, and easy-to-clean coating layers. In some embodiments, article100may be devoid of a coating layer (e.g., a coating layer150) disposed over or bonded to top surface124of cover glass layer120. In some embodiments, article100may be devoid of a polymeric hard-coating layer disposed over or bonded to top surface124of cover glass layer120. A polymeric hard-coating layer, such as the optically transparent polymeric (OTP) hard-coat layers described herein, is a layer with significant hardness configured to improve puncture and/or fracture resistance of an article. A cover glass layer120coated with one or more coating layers, or not coated with any coating layers, may be referred to a “cover substrate.”

Adhesive layer130is disposed between bottom surface122of cover glass layer120and top surface114of substrate110and bonds cover glass layer120to substrate110. In some embodiments, adhesive layer130may be disposed on top surface114of substrate110. In such embodiments, a bottom surface132of adhesive layer130is in direct contact with top surface114of substrate110. In some embodiments, adhesive layer130may be disposed on bottom surface122of cover glass layer120. In such embodiments, a top surface134of adhesive layer130is in direct contact with bottom surface122of cover glass layer120.

As used herein, “disposed on” means that a first layer and/or component is in direct contact with a second layer and/or component. A first layer and/or component “disposed on” a second layer and/or component may be deposited, formed, placed, or otherwise applied directly onto the second layer and/or component. In other words, if a first layer and/or component is disposed on a second layer and/or component, there are no layers disposed between the first layer and/or component and the second layer and/or component. A first layer and/or component described as “bonded to” a second layer and/or component means that the layers and/or components are bonded to each other, either by direct contact and/or bonding between the two layers and/or components or via an adhesive layer. If a first layer and/or component is described as “disposed over” a second layer and/or component, other layers may or may not be present between the first layer and/or component and the second layer and/or component.

Adhesive layer130may have a thickness136, measured from bottom surface132to a top surface134of adhesive layer130, in the range of 5 microns to 100 microns, including subranges therebetween. For example, thickness136of adhesive layer130may be 5 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 75 microns, 80 microns, 85 microns, 90 microns, 95 microns, 100 microns, or within a range having any two of these values as endpoints. In some embodiments, thickness136may be in the range of 25 microns to 75 microns. In some embodiments, adhesive layer130may be an optically transparent adhesive layer.

Adhesive layer130has a dynamic elastic modulus having a first elastic modulus measured in a first stress frequency range at room temperature and a second elastic modulus measured in a second stress frequency range at room temperature, where the first elastic modulus is less than the second elastic modulus and the first stress frequency range is lower than and does not overlap the second stress frequency range. For example, the first stress frequency range may be 0 Hertz to 5 Hertz and the second stress frequency range may be 10 Hertz to 1000 Hertz. In other words, adhesive layer130comprises a material with an elastic modulus that increases as the rate of stress loaded on the material increases.

As illustrated in graph300ofFIG.3, some adhesive materials may exhibit some limited shear thickening behavior. The limited shear thickening behavior of some materials is illustrated with a solid line in graph300. However, such a limited shear thickening behavior may not provide adequate impact resistance for article100. Adhesive layer materials disclosed herein have a high frequency modulus one to three orders of magnitude higher for high stress frequency loading. These materials are illustrated in graph300with a dashed line. The dynamic modulus of adhesive layer materials disclosed herein can be engineered through controlling crosslink types, crosslink density, and/or crystalline phase compositions of the materials to produce a material having characteristics represented by the dashed line inFIG.3—low elastic modulus at low stress frequency and suitably high elastic modulus at high stress frequency.

Graph1400inFIG.14illustrates the limited shear thickening behavior of an exemplary commercially available optically clear adhesive material (3M™ Optically Clear Adhesive8215). Graph1400shows the results of a dynamic mechanical analysis of this adhesive performed at zero degrees C. The analysis was performed at zero degrees C. because the glass transition temperature of this material is just below zero degrees C. To obtain a stable dynamic mechanical analysis response, it can be helpful to perform the analysis near the glass transition temperature of a material. As shown in graph1400, the elastic modulus (storage modulus) for this material achieves a maximum value of about 25 MPa within the stress frequency range of 10 Hertz to 1000 Hertz.

In some embodiments, the first elastic modulus of adhesive layer130may be in the range of 10 kPa (kilopascals) to 1000 kPa, including subranges therebetween, measured at a stress frequency in the range of 0 Hertz to 5 Hertz and a temperature of 23 degrees C. For example, the first elastic modulus of adhesive layer130may be 10 kPa, 50 kPa, 100 kPa, 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa, 700 kPa, 800 kPa, 900 kPa, or 1000 kPa, or within a range having any two of these values as endpoints. In some embodiments, first elastic modulus may be in the range of 10 kPa to 1000 kPa, including subranges therebetween, measured across the stress frequency range of 0 Hertz to 5 Hertz and at a temperature of 23 degrees C. For example, the first elastic modulus of adhesive layer130across the stress frequency range of 0 Hertz to 5 Hertz may be within a range having any of the following two values as endpoints: 10 kPa, 50 kPa, 100 kPa, 200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa, 700 kPa, 800 kPa, 900 kPa, or 1000 kPa.

Such a first elastic modulus within or across any of these ranges facilitates bending of article100at low bend forces and without failure. As used herein, the term “failure” under a bending force refers to breakage, destruction, delamination, crack propagation, permanent deformation, or other mechanisms that leave article100, a layer of article100(for example cover glass layer120), and/or a component of article100(for example substrate110) unsuitable for its intended purpose.

In some embodiments, first elastic modulus of adhesive layer130may facilitate bending of article100to at a plate distance “D” mm using a bend force172of 150 Newtons (N) or less as article100is bent inward (as shown inFIG.2) or outward (opposite direction as that shown inFIG.2). In some embodiments, the bending force is less than or equal to 150 N, 140 N, 130 N, 120 N, 110 N, 100 N, 90 N, 80 N, 70 N, 60 N, 50 N, 40 N, 30 N, 20 N, 10 N, or 5 N, or within a range having any two of these values as endpoints, upon bending of article100to a plate distance (D) of 40 mm to 1.5 mm), for example, 20 mm, 19.75 mm, 19.5 mm, 19.25 mm, 19 mm, 18.5 mm, 17.5 mm, 17 mm, 16.5 mm, 16 mm, 15.5 mm, 15 mm, 14.5 mm, 14 mm, 13.5 mm, and 13 mm, 12.5 mm, 12 mm, 11.5 mm, 11 mm, 10.5 mm, 10 mm, 9.5 mm, 9 mm, 8.5 mm, 7.5 mm, 7 mm, 6.5 mm, 6 mm, 5.5 mm, 5 mm, 4.5 mm, 4 mm, 3.5 mm, 3.25 mm, 3 mm, 2 mm, or 1.5 mm.

Referring toFIG.2, a bend force172is measured using a two-point bend test apparatus where two plates200are pressed against article100during a bending test with a constant force, bend force172. Fixtures associated with the test apparatus ensure that article100is bent symmetrically relative to line210as the bend force172is applied to article100via plates200. Plates200are moved together in unison until a particular plate distance is achieved.

In some embodiments, the second elastic modulus of adhesive layer130may be 500 MPa (megapascals) or more when measured at a stress frequency in the range of 10 Hertz to 1000 Hertz and a temperature of 23 degrees C. In some embodiments, the second elastic modulus of adhesive layer130may be in the range of 500 MPa to 10 GPa (gigapascals), including subranges therebetween, when measured at a stress frequency in the range of 10 Hertz to 1000 Hertz and a temperature of 23 degrees C. For example, the second elastic modulus of adhesive layer130may be 500 MPa, 600 MPa, 700 MPa, 750 MPa, 800 MPa, 900 MPa, 1 GPa, 2 GPa, 2.5 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7.5 GPa, 8 GPa, 9 GPa, or 10 GPa, or a within a range having any two of these values as endpoints. In some embodiments, the second elastic modulus of adhesive layer130may be in the range of 1 GPa to 10 GPa. In some embodiments, the second elastic modulus of adhesive layer130may greater than 10 GPa when measured at a stress frequency in the range of 10 Hertz to 1000 Hertz and a temperature of 23 degrees C. For example, second elastic modulus may be within a range having 11 GPa, 12 GPa, 13 GPa, 14 GPa, or 15 GPa as the upper limit. A second elastic modulus having such a value, or value range, helps prevent failure of article100during an impact event, such as a pen drop event or another drop event.

Suitable materials for adhesive layer130include, but are not limited to viscoelastic materials or shear thickening materials. In some embodiments, adhesive layer130may include, consist essentially of, or consist of a viscoelastic material. In some embodiments, adhesive layer130may include, consist essentially of, or consist of a shear thickening material.

One suitable type of shearing thickening adhesive material is a particle-based material comprising a high loading of colloidal particles dispersed in a suitable solution. The colloidal particles may be, but are not limited to, silica particles, poly(methyl methacrylate) (PMMA) particles, polystyrene (PS) particles, and their derivatives with different surface modifications. As used herein, a “colloidal” particle means a particle dispersed and insoluble in a solution in which it is mixed. In some embodiments, to ensure optical transparency, the average particle size of the colloidal particles may be 200 nm (nanometers) or less and/or the refractive index difference between the nanoparticles and solvent is less than or equal to 0.02 (e.g., in the range of 0.001 to 0.02). In other words, the colloidal nanoparticles may be composed of a material having a first refractive index, the solution may have a second refractive index, and the difference between the first refractive index and the second refractive index is 0.02 or less. The solution may be, but is not limited to, water, ethylene glycol (EG), and polyethylene glycol (PEG).

Such shear thickening fluids layers may be disposed on or over cover glass layer120using any of the following approaches. (1) By direct encapsulation of the shear thickening fluid between cover glass layer120and a capping layer (e.g., optional capping layer160shown inFIG.12). The capping layer may be a thin polymer layer or a thin glass layer. In such embodiments, the capping layer may be bonded to top surface114of substrate110. (2) Impregnating a shear thickening fluid into a continuous porous polymer network structure that adheres to bottom surface122of cover glass layer120. (3) Impregnating a shear thickening fluid into a closed porous polymer network structure that adheres to bottom surface122of cover glass layer120. For approaches #2 and #3, exemplary porous polymer network materials include, but are not limited to, polyurethane and siloxane. In some embodiments, the porous network may be a random or pre-defined ordered structure fabricated by a top-down or bottom-up fabrication method, such as a photolithography method or a self-assembly method.

Suitable viscoelastic shear thickening (dilatant) adhesive materials, include but are not limited to, polymer blends including one or more shear thickening fluids and composite materials made by mixing a reconfigurable supramolecular polymer with nanoparticles that possess dilatant behavior. Viscoelastic material properties of these materials can be engineered through controlling the crosslink types, the crosslink density, and/or the crystalline phase compositions of the materials.

Exemplary polymer blends may be formed by blending one or more shear thickening fluids, one or more rubber precursors, and a catalyzing agent. In some embodiments, a viscoelastic shear thickening adhesive may be formed by polymer blending with one or more shear thickening fluids to form multiple phase microstructures as described in U.S. Pat. Pub. No. 2010/0071893 A1, which is hereby incorporated in its entirety by reference thereto.

Exemplary supramolecular polymers include, but are not limited to, reversible hydrogen bond-based supramolecular polymers, metal-hydroxide modified siloxanes, such as boric-acid modified polydimethyl siloxane (PDMS), and reversible metal ligand-based supramolecular polymers as described in WO 2009/142491 A1, which is hereby incorporated in its entirety by reference thereto. In some embodiments, to ensure the optical transparency, the average size of the nanoparticles may be 200 nm or less and/or the refractive index difference between the nanoparticles and supramolecular polymer is less than or equal to 0.02 (e.g., in the range of 0.001 to 0.02). In other words, the nanoparticles may be composed of a material having a first refractive index, the supramolecular polymer may have a second refractive index, and the difference between the first refractive index and the second refractive index is 0.02 or less.

Dynamic finite element modeling was used to demonstrate the ability of adhesive layers with dynamic elastic moduli described herein to provide desired bendability and impact resistance for articles. The dynamic finite element modeling modeled the nonlinear material behavior of exemplary adhesive layers to evaluate stress imparted on an article100during a pen drop event. By modeling the stresses imparted by a Pen Drop Test (as described below and in connection withFIG.5), the degree of stresses imparted on a cover glass layer120and a substrate110can be analyzed to evaluate the ability of an adhesive layer to provide desired impact resistance for a foldable device.

As described and referred to herein, the modeled “Pen Drop Test” models the stresses imparted on surfaces of an article resulting from an impact load (for example, from a pen dropping at a certain height). For purposes of the model, a bottom surface of a cover glass layer is modeled as being bonded to a layer of polyethylene terephthalate (PET), acting as the substrate for the article, with an adhesive layer. The modeled PET layer in the Pen Drop Test is meant to simulate a flexible electronic display device (e.g., an OLED device). In the models, a modeled pen is dropped on a top surface of an article (top surface434inFIGS.4A and4B). A cover glass layer can fail on the top surface or a bottom surface (bottom surface432inFIGS.4A and4B) of the layer due to an impact force, so stresses on both of these surfaces were modeled to study the effects different adhesive materials.

FIGS.4A and4Billustrate the two test samples modeled. Both modeled test sample400aand modeled test sample400binclude a 50-micron thick cover glass layer430bonded to a 100-micron thick PET substrate410with a 50-micron thick adhesive layer420a/420b. The modeled cover glass layer430had a density of 2,450 kg/m3(kilograms per meter cubed), a modulus of elasticity of 71 GPa, and a Poisson's ratio of 0.22. The modeled PET substrate410had a density of 1,038 kg/m3, a modulus of elasticity of 5.4 GPa, and a Poisson's ratio of 0.38. The modeled adhesive layers420aand420bhad the same elastic modulus in a low frequency range but different elastic moduli in a high frequency range. In particular, the solid line inFIG.3is representative of the elastic modulus characteristics of modeled adhesive layer420aand the dashed line inFIG.3is representative of the elastic modulus characteristics of modeled adhesive layer420b. Since the modeled pen drop impact models an impact over a short period of time (for example, the time over which the modeled pen strikes top surface434of samples400aand400b), the Pen Drop Test evaluates a high stress frequency range (e.g., a stress frequency in the range of 10 Hertz to 1000 Hertz). Modeled adhesive layer420afor test sample400ahad an elastic modulus of 100 MPa for purposes of the pen drop impact. Modeled adhesive layer420bfor test sample400bhad an elastic modulus of 10 GPa for purposes of the pen drop impact.

FIG.5illustrates a finite element model500used to analyze impact stresses. Modeled cover glass layer430and substrate410of test samples400aand400bare in model500. For the model, top surface434of modeled cover glass layer430is loaded with puncture force and bottom surface432of modeled cover glass layers430is the surface bonded to top surface414of substrate410with adhesive layer420aand420b. In model500, the X-direction is measured on top surface434along the length518of modeled cover glass layer430, the Y-direction is measured on top surface434along the width519of modeled cover glass layer430, and the Z-direction is measured through the thickness516of modeled cover glass layer430from bottom surface432to top surface434. Pen drop height530is measured in the Z direction. For model500, a pen520was modeled to impart a puncture load on top surface434of modeled cover glass layer430. Pen520was modeled to replicate a BIC® Easy Glide Pen, Fine, having a tungsten carbide ball point tip522of 0.7 mm (0.68 mm) diameter (radius524of 0.34 mm), and a weight of 5.73 grams (which includes the weight of a BIC® Easy Glide Pen's cap). Bottom surface412of substrate410is modeled as being statically supported on a flat, hard surface.

FIG.6shows a graph600of the maximum principal stress distribution imparted on top surface434in the X-direction of model500for samples400aand400band for a pen drop height530of five centimeters (cm).FIG.7shows a graph700of the maximum principal stress distribution imparted on bottom surface432in the X-direction of model500for samples400aand400band for a pen drop height530of five centimeters (cm). In graph600, an X-direction value of zero is the point on the top surface434where the center of modeled ball point tip522contacts top surface434. In graph700, an X-direction value of zero is the point on bottom surface432directly below the point on top surface434in the Z-direction where the center of modeled ball point tip522contacts top surface434. Positive stress values indicate tensile stress, whereas negative stress values indicate compressive stress.

As evident inFIG.6, the finite element analysis shows that by increasing the adhesive layer stiffness from 100 MPa to 10 GPa, the maximum principal tensile stress on top surface434of modeled cover glass layer430drops from about 2723 MPa to about 2457 MPa (a decrease of about 10%). Similarly, as shown inFIG.7, the finite element analysis shows that the maximum principal tensile stress on bottom surface432of modeled cover glass layer430drops from about 7869 MPa to about 6590 MPa (a decrease of about 16%). These results indicate that the stiffer adhesive layer420bof sample400bimproves impact resistance.

As evident in graph800ofFIG.8, the finite element analysis shows that by increasing the adhesive layer stiffness from 100 MPa to 10 GPa, the maximum principal tensile stress on top surface414of substrate410increases by about 24%. Similarly, as evident in graph900ofFIG.9, the finite element analysis shows that the maximum principal tensile stress on bottom surface412of substrate410increases by about 230%. However, as illustrated in bar graph1000ofFIG.10, the magnitude of the maximum principal tensile stresses on these surfaces of substrate410is much lower than those on top surface434and bottom surface432of modeled cover glass layer430. So, such an increase in stress does not significantly affect the overall impact resistance of the samples.

So, as shown inFIGS.6-10, tailoring the dynamic elastic modulus of an adhesive layer to have a sufficiently high elastic modulus in a high stress frequency range, such as 10 Hertz to 1000 Hertz, can improve the impact resistance of an article. A sufficiently high elastic modulus at high stress frequency can reduce the maximum principal tensile stress imparted on top and bottom surfaces of a cover glass layer. By reducing the maximum stresses, the cover glass layer is less likely to fail during an impact event.

In some embodiments, adhesive layer130may include, consist essentially of, or consist of a material having a glass transition temperature (Tg) higher than the intended operating temperature of article100. This can be beneficial, because as illustrated in graph1100ofFIG.11A, a material with a Tghigher than the operating temperature (Top) would be in a glassy state at the operating temperature, and thus would exhibit a relatively higher stiffness than a material with a Tgless than the intended operating temperature. The dotted line inFIG.11Aillustrates the shear modulus (G) of a material with a Tghigher than the operating temperature and the solid line illustrates the shear modulus of a material with a Tglower than the operating temperature. The shear modulus of the dotted line remains high at the operating temperature; thus, the material will be relatively stiff at the operating temperature. In contrast, the shear modulus of the solid line is lower at the operating temperature; thus, the material will be relatively flexible at the operating temperature. In some embodiments, the intended operating temperature of article100may be 23 degrees C. As shown in the model above, a stiffer adhesive material can help improve impact resistance of an article.

In some embodiments, adhesive layer130may include, consist essentially of, or consist of a material having a glass transition temperature (Tg) lower than the intended operating temperature of article100. This can be beneficial because an adhesive as described herein with a Tglower than the operating temperature can assist in dissipating stress imparted on an article. As illustrated in graph1150ofFIG.11B, upon application of a stress (σ2) at time t1, a material with a Tglower than Topwill dissipate the stress over time (illustrated with a solid line) during which the stress is applied. In contrast, for a material with a Tghigher than Top, the applied stress on the material will remain constant during the time the stress is applied (illustrated with a dotted line). The ability of a material with a Tglower than Topto dissipate an applied stress can be beneficial during application of a bending force and/or impact force. By dissipating the applied stress, the material relieves stress on other layers of article100, thereby reducing the chance these layers fail.

In some embodiments, for example as shown inFIG.12, glass article100may be coated with a coating layer150having a bottom surface152, a top surface154, and a thickness156. In some embodiments, a coating layer150may be bonded to top surface124of cover glass layer120with an adhesive layer. In some embodiments, coating layer150may disposed on top surface124of cover glass layer120. In some embodiments, multiple coating layers150, of the same or different types, may be coated on a glass article100.

In some embodiments, a coating layer150may be an inorganic optically transparent hard-coat layer, for example a silicon dioxide (SiO2) or aluminum oxide (Al2O3) layer deposited by a physical vapor deposition process, a chemical vapor deposition process or an atomic layer deposition process. In some embodiments, a coating layer150may be an optically transparent polymeric (OTP) hard-coat layer. An inorganic or OTP hard-coat layer may have a pencil hardness of, for example, 7H, 8H, or 9H.

Suitable materials for an OTP hard-coat layer include, but are not limited to, a polyimide, a polyethylene terephthalate (PET), a polycarbonate (PC), a poly methyl methacrylate (PMMA), organic polymer materials, inorganic-organic hybrid polymeric materials, and aliphatic or aromatic hexafunctional urethane acrylates. In some embodiments, an OTP hard-coat layer may consist essentially of an organic polymer material, an inorganic-organic hybrid polymeric material, or aliphatic or aromatic hexafunctional urethane acrylate. In some embodiments, an OTP hard-coat layer may consist of a polyimide, an organic polymer material, an inorganic-organic hybrid polymeric material, or aliphatic or aromatic hexafunctional urethane acrylate. In some embodiments, an OTP hard-coat layer may include a nanocomposite material. In some embodiments, an OTP hard-coat layer may include a nano-silicate at least one of epoxy or urethane materials. Suitable compositions for such an OTP hard-coat layer are described in U.S. Pat. Pub. No. 2015/0110990, which is hereby incorporated by reference in its entirety by reference thereto.

As used herein, “organic polymer material” means a polymeric material comprising monomers with only organic components. In some embodiments, an OTP hard-coat layer may comprise an organic polymer material manufactured by Gunze Limited and having a hardness of 9H, for example Gunze's “Highly Durable Transparent Film.” As used herein, “inorganic-organic hybrid polymeric material” means a polymeric material comprising monomers with inorganic and organic components. An inorganic-organic hybrid polymer is obtained by a polymerization reaction between monomers having an inorganic group and an organic group. An inorganic-organic hybrid polymer is not a nanocomposite material comprising separate inorganic and organic constituents or phases, for example inorganic particulate dispersed within an organic matrix.

In some embodiments, the inorganic-organic hybrid polymeric material may include polymerized monomers comprising an inorganic silicon-based group, for example, a silsesquioxane polymer. A silsesquioxane polymer may be, for example, an alky-silsesquioxane, an aryl-silsesquioxane, or an aryl alkyl-silsesquioxane having the following chemical structure: (RSiO1.5)n, where R is an organic group for example, but not limited to, methyl or phenyl. In some embodiments, an OTP hard-coat layer may comprise a silsesquioxane polymer combined with an organic matrix, for example, SILPLUS manufactured by Nippon Steel Chemical Co., Ltd.

In some embodiments, an OTP hard-coat layer may comprise 90 wt % to 95 wt % aromatic hexafunctional urethane acrylate (e.g., PU662NT (Aromatic hexafunctional urethane acrylate) manufactured by Miwon Specialty Chemical Co.) and 10 wt % to 5 wt % photo-initiator (e.g., Darocur 1173 manufactured by Ciba Specialty Chemicals Corporation) with a hardness of 8H or more. In some embodiments, an OTP hard-coat layer composed of an aliphatic or aromatic hexafunctional urethane acrylate may be formed as a stand-alone layer by spin-coating the layer on a polyethylene terephthalate (PET) substrate, curing the urethane acrylate, and removing the urethane acrylate layer from the PET substrate.

An OTP hard-coat layer may have a thickness156in the range of 10 microns to 120 microns, including subranges therebetween. For example, an OTP hard-coat layer may have a thickness156of 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, or within a range having any two of these values as endpoints. In some embodiments, an OTP hard-coat layer may be a single monolithic layer.

In some embodiments, an OTP hard-coat layer may be an inorganic-organic hybrid polymeric material layer or an organic polymer material layer having a thickness in the range of 80 microns to 120 microns, including subranges therebetween. For example, an OTP hard-coat layer comprising an inorganic-organic hybrid polymeric material, or an organic polymer material may have a thickness of 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, or within a range having any two of these values as end points. In some embodiments, an OTP hard-coat layer may be an aliphatic or aromatic hexafunctional urethane acrylate material layer having a thickness in the range of 10 microns to 60 microns, including subranges therebetween. For example, an OTP hard-coat layer comprising an aliphatic or aromatic hexafunctional urethane acrylate material may have a thickness of 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, or within a range having any two of these values as end points.

In some embodiments, coating layer(s)150may be an anti-reflection coating layer. Exemplary materials suitable for use in the anti-reflection coating layer include: SiO2, Al2O3, GeO2, SiO, AlOxNy, AlN, SiNx, SiOxNy, SiuAlvOxNy, Ta2O5, Nb2O5, TiO2, ZrO2, TiN, MgO, MgF2, BaF2, CaF2, SnO2, HfO2, Y2O3, MoO3, DyF3, YbF3, YF3, CeF3, polymers, fluoropolymers, plasma-polymerized polymers, siloxane polymers, silsesquioxanes, polyimides, fluorinated polyimides, polyetherimide, polyethersulfone, polyphenylsulfone, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, acrylic polymers, urethane polymers, polymethylmethacrylate, and other materials cited above as suitable for use in a scratch resistant layer. An anti-reflection coating layer may include sub-layers of different materials.

In some embodiments, the anti-reflection coating layer may include a hexagonally packed nanoparticle layer, for example but not limited to, the hexagonally packed nanoparticle layers described in U.S. Pat. No. 9,272,947, issued Mar. 1, 2016, which is hereby incorporated by reference in its entirety by reference thereto. In some embodiments, the anti-reflection coating layer may include a nanoporous Si-containing coating layer, for example but not limited to the nanoporous Si-containing coating layers described in WO2013/106629, published on Jul. 18, 2013, which is hereby incorporated by reference in its entirety by reference thereto. In some embodiments, the anti-reflection coating may include a multilayer coating, for example, but not limited to the multilayer coatings described in WO2013/106638, published on Jul. 18, 2013; WO2013/082488, published on Jun. 6, 2013; and U.S. Pat. No. 9,335,444, issued on May 10, 2016, all of which are hereby incorporated by reference in their entirety by reference thereto.

In some embodiments, coating layer(s)150may be an easy-to-clean coating layer. In some embodiments, the easy-to-clean coating layer may include a material selected from the group consisting of fluoroalkylsilanes, perfluoropolyether alkoxy silanes, perfluoroalkyl alkoxy silanes, fluoroalkylsilane-(non-fluoroalkylsilane) copolymers, and mixtures of fluoroalkylsilanes. In some embodiments, the easy-to-clean coating layer may include one or more materials that are silanes of selected types containing perfluorinated groups, for example, perfluoroalkyl silanes of formula (RF)ySiX4-y, where RF is a linear C6-C30perfluoroalkyl group, X=Cl, acetoxy, —OCH3, and —OCH2CH3, and y=2 or 3. The perfluoroalkyl silanes can be obtained commercially from many vendors including Dow-Corning (for example fluorocarbons 2604 and 2634), 3MCompany (for example ECC-1000 and ECC-4000), and other fluorocarbon suppliers, for example Daikin Corporation, Ceko (South Korea), Cotec-GmbH (DURALON UltraTec materials) and Evonik. In some embodiments, the easy-to-clean coating layer may include an easy-to-clean coating layer as described in WO2013/082477, published on Jun. 6, 2013, which is hereby incorporated by reference in its entirety by reference thereto.

In some embodiments, coating layer(s)150may be an anti-glare layer formed on top surface124of cover glass layer120. Suitable anti-glare layers include, but are not limited to, the anti-glare layers prepared by the processes described in U.S. Pat. Pub. Nos. 2010/0246016, 2011/0062849, 2011/0267697, 2011/0267698, 2015/0198752, and 2012/0281292, all of which are hereby incorporated by reference in their entirety by reference thereto.

In some embodiments, coating layer(s)150may be an anti-fingerprint coating layer. Suitable anti-fingerprint coating layers include, but are not limited to, oleophobic surface layers including gas-trapping features, as described in, for example, U.S. Pat. App. Pub. No. 2011/0206903, published Aug. 25, 2011, and oleophilic coatings formed from an uncured or partially-cured siloxane coating precursor comprising an inorganic side chain that is reactive with the surface of the glass or glass-ceramic substrate (e.g., partially-cured linear alkyl siloxane), as described in, for example, U.S. Pat. App. Pub. No. 2013/0130004, published May 23, 2013. The contents of U.S. Pat. App. Pub. No. 2011/0206903 and U.S. Pat. App. Pub. No. 2013/0130004 are incorporated herein by reference in their entirety.

In some embodiments, coating layer(s)150may be an anti-microbial and/or anti-viral layer may be formed on top surface124of cover glass layer120. Suitable anti-microbial and/or anti-viral layers include, but are not limited to, an antimicrobial Ag+ region extending from the surface of the glass article to a depth in the glass article having a suitable concentration of Ag+1 ions on the surface of the glass article, as described in, for example, U.S. Pat. App. Pub. No. 2012/0034435, published Feb. 9, 2012, and U.S. Pat. App. Pub. No. 2015/0118276, published Apr. 30, 2015. The contents of U.S. Pat. App. Pub. No. 2012/0034435 and U.S. Pat. App. Pub. No. 2015/0118276 are incorporated herein by reference in their entirety.

FIG.13shows a consumer electronic product1300according to some embodiments. Consumer electronic product1300may include a housing1302having a front (user-facing) surface1304, a back surface1306, and side surfaces1308. Electrical components may be at least partially within housing1302. The electrical components may include, among others, a controller1310, a memory1312, and display components, including a display1314. In some embodiments, display1314may be at or adjacent to front surface1304of housing1302. Display1314may be, for example, a light emitting diode (LED) display or an organic light emitting diode (OLED) display.

As shown for example inFIG.13, consumer electronic product1300may include a cover substrate1320. Cover substrate1320may be a cover glass layer as disclosed herein. Cover substrate1320may serve to protect display1314and other components of consumer electronic product1300(e.g., controller1310and memory1312) from damage. In some embodiments, cover substrate1320may be disposed over display1314. In some embodiments, cover substrate1320may be bonded to display1314with an adhesive layer as disclosed herein. Cover substrate1320may be a 2D, 2.5D, or 3D cover substrate. In some embodiments, cover substrate1320may define front surface1304of housing1302. In some embodiments, cover substrate1320may define front surface1304of housing1302and all or a portion of side surfaces1308of housing1302. In some embodiments, consumer electronic product1300may include a cover substrate defining all or a portion of back surface1306of housing1302.

As used herein the term “glass” is meant to include any material made at least partially of glass, including glass and glass-ceramics. “Glass-ceramics” include materials produced through controlled crystallization of glass. In embodiments, glass-ceramics have about 30% to about 90% crystallinity. Non-limiting examples of glass ceramic systems that may be used include Li2O×Al2O3×nSiO2(i.e. LAS system), MgO×Al2O3×nSiO2(i.e. MAS system), and ZnO×Al2O3×nSiO2(i.e. ZAS system).

Examples of suitable glass include soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass. In some variants, the glass may either include lithia or be free of lithia. In one or more alternative embodiments, the glass may be a crystalline glass, for example a glass-ceramic (which may be strengthened or non-strengthened) or may include a single crystal structure, for example sapphire. In one or more specific embodiments, a glass layer may include an amorphous glass base and a crystalline cladding (e.g., sapphire layer, a polycrystalline alumina layer and/or or a spinel (MgAl2O4) layer).

In some embodiments, the glass composition for glass layers discussed herein may include 40 mol % to 90 mol % SiO2(silicon oxide). In some embodiments, the glass composition may include 40 mol %, 45 mol %, 50 mol %, 55 mol %, 60 mol %, 65 mol %, 70 mol %, 75 mol %, 80 mol %, 85 mol %, or 90 mol % SiO2, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 55 mol % to 70 mol % SiO2. In some embodiments, the glass composition may include 57.43 mol % to 68.95 mol % SiO2.

In some embodiments, the glass composition for glass layers discussed herein may include 1 mol % to 10 mol % B2O3(boron oxide). In some embodiments, the glass composition may include 1 mol %, 2 mol %, 3 mol %, 4 mol %, 5 mol %, 6 mol %, 7 mol %, 8 mol %, 9 mol %, or 10 mol % B2O3, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 3 mol % to 6 mol % B2O3. In some embodiments, the glass composition may include 3.86 mol % to 5.11 mol % B2O3. In some embodiments, the glass composition may not include B2O3.

In some embodiments, the glass composition for glass layers discussed herein may include 5 mol % to 30 mol % Al2O3(aluminum oxide). In some embodiments, the glass composition may include 5 mol %, 10 mol %, 15 mol %, 20 mol %, 25 mol %, or 30 mol % Al2O3, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 10 mol % to 20 mol % Al2O3. In some embodiments, the glass composition may include 10.27 mol % to 16.10 mol % Al2O3.

In some embodiments, the glass composition for glass layers discussed herein may include 1 mol % to 10 mol % P2O5(phosphorus oxide). In some embodiments, the glass composition may include 1 mol %, 2 mol %, 3 mol %, 4 mol %, 5 mol %, 6 mol %, 7 mol %, 8 mol %, 9 mol %, or 10 mol % P2O5, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 2 mol % to 7 mol % P2O5. In some embodiments, the glass composition may include 2.47 mol % to 6.54 mol % P2O5. In some embodiments, the glass composition may not include P2O5.

In some embodiments, the glass composition for glass layers discussed herein may include 5 mol % to 30 mol % Na2O (sodium oxide). In some embodiments, the glass composition may include 5 mol %, 10 mol %, 15 mol %, 20 mol %, 25 mol %, or 30 mol % Na2O, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 10 mol % to 20 mol % Na2O. In some embodiments, the glass composition may include 10.82 mol % to 17.05 mol % Na2O.

In some embodiments, the glass composition for glass layers discussed herein may include 0.01 mol % to 0.05 mol % K2O (potassium oxide). In some embodiments, the glass composition may include 0.01 mol %, 0.02 mol %, 0.03 mol %, 0.04 mol %, or 0.05 mol % K2O, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 0.01 mol % K2O. In some embodiments, the glass composition may not include K2O.

In some embodiments, the glass composition for glass layers discussed herein may include 1 mol % to 10 mol % MgO (magnesium oxide). In some embodiments, the glass composition may include 1 mol %, 2 mol %, 3 mol %, 4 mol %, 5 mol %, 6 mol %, 7 mol %, 8 mol %, 9 mol %, or 10 mol % MgO, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 2 mol % to 6 mol % MgO. In some embodiments, the glass composition may include 2.33 mol % to 5.36 mol % MgO. In some embodiments, the glass composition may not include MgO.

In some embodiments, the glass composition for glass layers discussed herein may include 0.01 mol % to 0.1 mol % CaO (calcium oxide). In some embodiments, the glass composition may include 0.01 mol %, 0.02 mol %, 0.03 mol %, 0.04 mol %, 0.05 mol %, 0.06 mol %, 0.07 mol %, 0.08 mol %, 0.09 mol %, or 0.1 mol % CaO, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 0.03 mol % to 0.06 mol % CaO. In some embodiments, the glass composition may not include CaO.

In some embodiments, the glass composition for glass layers discussed herein may include 0.01 mol % to 0.05 mol % Fe2O3(iron oxide). In some embodiments, the glass composition may include 0.01 mol %, 0.02 mol %, 0.03 mol %, 0.04 mol %, or 0.05 mol % Fe2O3, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 0.01 mol % Fe2O3. In some embodiments, the glass composition may not include Fe2O3.

In some embodiments, the glass composition for glass layers discussed herein may include 0.5 mol % to 2 mol % ZnO (zinc oxide). In some embodiments, the glass composition may include 0.5 mol %, 1 mol %, 1.5 mol %, or 2 mol % ZnO, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 1.16 mol % ZnO. In some embodiments, the glass composition may not include ZnO.

In some embodiments, the glass composition for glass layers discussed herein may include 1 mol % to 10 mol % Li2O (lithium oxide). In some embodiments, the glass composition may include 1 mol %, 2 mol %, 3 mol %, 4 mol %, 5 mol %, 6 mol %, 7 mol %, 8 mol %, 9 mol %, or 10 mol % Li2O, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 5 mol % to 7 mol % Li2O. In some embodiments, the glass composition may include 6.19 mol % Li2O. In some embodiments, the glass composition may not include Li2O.

In some embodiments, the glass composition for glass layers discussed herein may include 0.01 mol % to 0.3 mol % SnO2(tin oxide). In some embodiments, the glass composition may include 0.01 mol %, 0.05 mol %, 0.1 mol %, 0.15 mol %, 0.2 mol %, 0.25 mol %, or 0.3 mol %, SnO2, or a mol % within any range having any two of these values as end points. In some embodiments, the glass composition may include 0.01 mol % to 0.2 mol % SnO2. In some embodiments, the glass composition may include 0.04 mol % to 0.17 mol % SnO2.

In some embodiments, the glass composition for glass layers discussed herein may be a composition including a value for R2O (alkali metal oxide(s))+RO (alkali earth metal oxide(s)) in the range of 10 mol % to 30 mol %. In some embodiments, R2O+RO may be 10 mol %, 15 mol %, 20 mol %, 25 mol %, or 30 mol %, or a mol % within any range having any two of these values as end points. In some embodiments, R2O+RO may be in the range of 15 mol % to 25 mol %. In some embodiments, R2O+RO may be in the range of 16.01 mol % to 20.61 mol %.

A substrate or layer may be strengthened to form a strengthened substrate or layer. As used herein, the terms “strengthened substrate” or “strengthened layer” may refer to a substrate and/or layer that has been chemically strengthened, for example through ion exchange of larger ions for smaller ions in the surface of the substrate and/or layer. Other strengthening methods in the art, for example thermal tempering, or utilizing a mismatch of the coefficient of thermal expansion between portions of the substrate and/or layer to create compressive stress and central tension regions, may also be utilized to form strengthened substrates and/or layers.

Where the substrate and/or layer is chemically strengthened by an ion exchange process, the ions in the surface layer of the substrate and/or layer are replaced by—or exchanged with—larger ions having the same valence or oxidation state. Ion exchange processes are typically carried out by immersing a substrate and/or layer in a molten salt bath containing the larger ions to be exchanged with the smaller ions in the substrate. It will be appreciated by those skilled in the art that parameters for the ion exchange process, including, but not limited to, bath composition and temperature, immersion time, the number of immersions of the substrate and/or layer in a salt bath (or baths), use of multiple salt baths, additional steps, for example annealing, washing, and the like, are generally determined by the composition of the substrate and/or layer and the desired compressive stress (CS), depth of compressive stress layer (or depth of layer) of the substrate that result from the strengthening operation. By way of example, ion exchange of alkali metal-containing glass substrates and/or layers may be achieved by immersion in at least one molten bath containing a salt for example, but not limited to, nitrates, sulfates, and chlorides of the larger alkali metal ion. The temperature of the molten salt bath typically is in a range from about 380° C. up to about 450° C., while immersion times range from about 15 minutes up to about 40 hours. However, temperatures and immersion times different from those described above may also be used.

In addition, non-limiting examples of ion exchange processes in which glass substrates and/or layers are immersed in multiple ion exchange baths, with washing and/or annealing steps between immersions, are described in U.S. patent application Ser. No. 12/500,650, filed Jul. 10, 2009, by Douglas C. Allan et al., entitled “Glass with Compressive Surface for Consumer Applications,” claiming priority from U.S. Provisional Patent Application No. 61/079,995, filed Jul. 11, 2008, and patented as U.S. Pat. No. 8,561,429 on Oct. 22, 2013, in which glass substrates are strengthened by immersion in multiple, successive, ion exchange treatments in salt baths of different concentrations; and U.S. Pat. No. 8,312,739, by Christopher M. Lee et al., issued on Nov. 20, 2012, and entitled “Dual Stage Ion Exchange for Chemical Strengthening of Glass,” and claiming priority from U.S. Provisional Patent Application No. 61/084,398, filed Jul. 29, 2008, in which glass substrates are strengthened by ion exchange in a first bath is diluted with an effluent ion, followed by immersion in a second bath having a smaller concentration of the effluent ion than the first bath. The contents of U.S. Pat. Nos. 8,561,429 and 8,312,739 are incorporated herein by reference in their entirety.

While various embodiments have been described herein, they have been presented by way of example, and not limitation. It should be apparent that adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It therefore will be apparent to one skilled in the art that various changes in form and detail can be made to the embodiments disclosed herein without departing from the spirit and scope of the present disclosure. The elements of the embodiments presented herein are not necessarily mutually exclusive, but may be interchanged to meet various situations as would be appreciated by one of skill in the art.

Embodiments of the present disclosure are described in detail herein with reference to embodiments thereof as illustrated in the accompanying drawings, in which like reference numerals are used to indicate identical or functionally similar elements. References to “one embodiment,” “an embodiment,” “some embodiments,” “in certain embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

The examples are illustrative, but not limiting, of the present disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the art, are within the spirit and scope of the disclosure.

The term “or,” as used herein, is inclusive; more specifically, the phrase “A or B” means “A, B, or both A and B.” Exclusive “or” is designated herein by terms such as “either A or B,” for example.

The indefinite articles “a” and “an” to describe an element or component means that one or at least one of these elements or components is present. Although these articles are conventionally employed to signify that the modified noun is a singular noun, as used herein the articles “a” and “an” also include the plural, unless otherwise stated in specific instances. Similarly, the definite article “the,” as used herein, also signifies that the modified noun may be singular or plural, again unless otherwise stated in specific instances.

As used in the claims, “comprising” is an open-ended transitional phrase. A list of elements following the transitional phrase “comprising” is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present. As used in the claims, “consisting essentially of” or “composed essentially of” limits the composition of a material to the specified materials and those that do not materially affect the basic and novel characteristic(s) of the material. As used in the claims, “consisting of” or “composed entirely of” limits the composition of a material to the specified materials and excludes any material not specified.

The term “wherein” is used as an open-ended transitional phrase, to introduce a recitation of a series of characteristics of the structure.

Where a range of numerical values is recited herein, comprising upper and lower values, unless otherwise stated in specific circumstances, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the claims be limited to the specific values recited when defining a range. Further, when an amount, concentration, or other value or parameter is given as a range, one or more preferred ranges or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether such pairs are separately disclosed. Finally, when the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to. Whether or not a numerical value or end-point of a range recites “about,” the numerical value or end-point of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.”

As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art.

The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, for example within about 5% of each other, or within about 2% of each other.

The present embodiment(s) have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

It is to be understood that the phraseology or terminology used herein is for the purpose of description and not of limitation. The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined in accordance with the following claims and their equivalents.