Patent Description:
Recently there has been increased need for glass articles to be flexible for use in a variety of applications that require the glass to be flexible and bendable. For example, flexible display devices for mobile phones, tablets and other portable electronic devices include flexible glass that must be bendable or foldable without breaking. However, glass had been traditionally considered rigid in nature, and therefore alternative materials have been considered for use instead of glass. For example, flexible films made of polymer have been considered and researched for use in flexible display devices as an alternative for glass. The flexible film indeed provided necessary flexibility, but did not meet the necessary durability, resistance to scratch, chemical resistance, and optical characteristics for such applications.

Chemically strengthened glass panels also have been considered for use as flexible glass, but the chemically strengthened glass panels showed relatively large bending radii of greater than <NUM>. For example, when using glass chemically strengthened to have increased surface compression, in order for the chemically strengthened glass to have a bending radius of <NUM>, the thickness of the glass would have to be about <NUM>, and to have a bending radius of <NUM>, the thickness the glass would have to be about <NUM>.

However, it is practically impossible to reduce the thickness of a glass panel to less than <NUM> using glass etching, which is conventionally used to reduce thickness of glass from between <NUM> and <NUM> to less than <NUM>, because of lack of uniformity. Examples may be found in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concepts, and, therefore, it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

Flexible glass articles constructed according to the principles of the invention and methods of making the same avoid one or more of the problems and/or drawbacks of conventional glass articles by providing an ultra-low bending curvature, while still retaining a thin profile and other favorable characteristics of glass.

Additional aspects will be set forth in the detailed description which follows, and, in part, will be apparent from the disclosure, or may be learned by practice of the inventive concepts.

According to an exemplary embodiment, a flexible glass article includes: a glass element having a first thickness of about <NUM> to about <NUM> and including first and second opposed surfaces, and a compressive stress region extending from the first surface of the glass element to a first depth in the glass element, the compressive stress region having a compressive stress of at least about <NUM> MPa at the first surface of the glass element; and a coating directly cured by ultraviolet radiation on the second surface of the glass element, the coating having a second thickness substantially equal to or greater than three times the first thickness, wherein the glass article is of an absence of fracture when the glass element is bent with the first surface disposed toward the inside of the bend and held at a bend radius of about <NUM> to about <NUM> for at least <NUM> minutes at about <NUM> and about <NUM> % relative humidity.

The coating included in the flexible glass article has an elastic modulus equal to or less then <NUM> GPa.

The glass article of the flexible glass article may further characterized by: an absence of fracture when the glass is bent over approximately <NUM>,<NUM> cycles.

The second thickness is equal to or less than <NUM>.

The polymer may include at least one material selected from the group consisting of polyester acrylate and polyimide.

The glass article may be further characterized by: an impact resistance against a drop from a height of about <NUM> of a pen having a weight of about <NUM> and a tip diameter of about <NUM>.

The glass article may be further characterized by: a change of yellow index equal to or less than about <NUM>% after the glass article is exposed to a ultraviolet light having wavelength substantially between about <NUM> and about <NUM> for approximately <NUM> hours.

The compressive stress of the compressive stress region of the glass element may be substantially from about <NUM> MPa to about <NUM> MPa.

The first depth may be at least about <NUM>.

The flexible glass article may have percentage haze substantially equal to or less than about <NUM> %.

The coating is formed directly on the second surface of the glass element.

A flexible display device may include the above glass article.

The glass article may be incorporated in a mobile phone, tablet, laptop, watch or other portable electronic device.

According to an exemplary embodiment, a method of manufacturing a flexible glass article includes the steps of: preparing a glass element having a first thickness and having first and second surfaces; chemically strengthening the glass element to form a compressive stress region extending from the first surface of the glass element to a first depth in the glass element, the compressive stress region having a compressive stress of at least about <NUM> MPa at the first surface of the glass element; and forming a coating directly on the second surface of the glass element, the coating having a second thickness substantially equal to or greater than three times the first thickness, wherein the glass article is of an absence of fracture when the glass element is bent with the first surface disposed toward the inside of the bend and held at a bend radius of about <NUM> to about <NUM> for at least <NUM> minutes at about <NUM> and about <NUM> % relative humidity.

The step of forming the coating further includes: applying a coating solution on the second surface of the glass element; applying a soft mold on the coating solution; forming the coating by exposing the glass element to ultraviolet radiation to cure the coating solution; and removing the soft mold.

The step of forming the coating may further include: exposing the coating to ultraviolet radiation after removing the soft mold.

The coating solution may include at least one material selected from the group consisting of Poly(methyl methacrylate) PMMA, Polyethylene terephthalate PET, Cellulose triacetate TAC, Polyether sulfone PES, Ethylene tetrafluoroethylene ETFE, Fluorinated ethylene propylene FEP, Perfluoroalkoxy alkane PFA, organic polymer ORGA, Polycarbonate PC , Fiber-reinforced plastic FRP, Polyurethane, Polyester, Polyaramid, Polypropylene PP, Polyethylene naphthalate PEN, and Polyimide.

The step of chemically strengthening the glass element may include: exchanging sodium ion (Na+) in the glass element with potassium ion (K+) through a Na-K ion exchange reaction.

The step of chemically strengthening the glass element may further include: submerging the glass element in potassium nitride (KNO3) bath.

Herein disclosed is a method of adjusting an effective bending radius of a glass article subject to bending stress to fold the glass article from a natural bending radius of about <NUM> to <NUM> to a modified bending radius of about <NUM> to <NUM> may include the steps of: providing a glass element having first and a second opposed surfaces and first thickness in the range of about <NUM> to about <NUM>; chemically strengthening the glass element to form a compressive stress region extending from the first surface of the glass element to a first depth in the glass element, and forming a coating integrally on the second surface of the glass element, the coating having a second thickness substantially equal to or greater than three times the first thickness.

The step of forming the coating may include: applying a coating solution on the second surface of the glass element; applying a soft mold on the coating solution; forming the coating by exposing the glass element to ultraviolet radiation to cure the coating solution; and removing the soft mold.

The step of chemically strengthening the glass element may include: submerging the glass in potassium nitride (KNO3) bath; and exchanging sodium ion (Na+) in the glass element with potassium ion (K+) through Na-K ion exchange reaction.

The step of chemically strengthening the glass element may include forming the compressive stress region to have a compressive stress of at least about <NUM> MPa at the first surface of the glass element.

The glass article may be characterized by an absence of fracture when the glass element is bent with the first surface disposed toward the inside of the bend and held at a bend radius of about <NUM> to about <NUM> for at least <NUM> minutes at about <NUM> and about <NUM> % relative humidity.

A neutral axis of the glass article may be shifted toward the coating in response to an increase in the second thickness of the coating, wherein the neutral axis of the glass article has zero tensile when the glass article is bent.

The foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the claimed subject matter.

The accompanying drawings, which are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the inventive concept, and, together with the description, serve to explain principles of the inventive concept.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments.

In the accompanying figures, the size and relative sizes of layers, films, panels, regions, etc., may be exaggerated for clarity and descriptive purposes.

When an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present.

Although the terms first, second, 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 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 discussed below could be termed a second element, component, region, layer, and/or section without departing from the teachings of the present disclosure.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein for descriptive purposes, and, thereby, to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the drawings.

Various exemplary embodiments are described herein with reference to sectional illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. Thus, exemplary embodiments disclosed herein should not be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. Thus, the regions illustrated in the drawings are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to be limiting.

Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

<FIG> is schematic side view of an exemplary embodiment of a flexible glass article <NUM> constructed according to the principles of the invention. Referring to <FIG>, the flexible glass article <NUM> comprises a glass element <NUM> and a coating <NUM>. The glass element <NUM> may be a flexible glass, and the coating <NUM> may be provided to control a characteristic of the glass element <NUM> and the flexible glass article <NUM>. The coating <NUM> may include a polymer that has an optical characteristic adequate for use as a window, and may be formed on the glass element <NUM>. For example, the coating <NUM> may include at least one of polyester acrylate and polyimide. Contrary to conventional glass, the coating is thicker than the glass itself for reasons that will be discussed herein.

The glass element <NUM>, under conditions of static bent status or dynamic bending status, follows fracture mechanics of brittle material. Similar to other brittle materials, glass shows greater fracture toughness against compressive stress than tensile stress, and failure generally occurs when tensile stress is applied to the glass. Following are descriptions of the two circumstances glass fails under stress.

First is failure directly from an application of stress. The glass will break in response to the application of the stress when the stress intensity factor (KI), which represents the stress applied to flaws embedded within the glass, is greater than the fracture toughness (KIC), which may be between <NUM> MPa·m<NUM> and <NUM> MPa·m<NUM> for glass, from cracks propagating in a very high speed. Such failure occurs according to the following formula (<NUM>): <MAT>.

Wherein KI is the stress intensity factor, Y is a geometry factor of the flaw, σ is the applied stress, and a stands for the size of the flaw.

On the other hand, a fatigue fracture of the glass under static stress occurs differently. Under static stress, sizes of the flaws embedded in the glass slowly grow according to environmental factors, such as relative humidity, resulting in propagation of cracks and the failure of the glass. The speed of the flaw size growth is proportional to the stress intensity factor and the relative humidity.

<FIG> is a graph illustrating the three different speeds of crack velocity of glass articles. Referring to <FIG>, The crack grows slowly in response to the stress intensity factor and the relative humidity in I region resulting in fatigue fracture, and the crack grows rapidly in response to stress intensity in III region, where the environmental factors are excluded, resulting in fracture or breakage of the glass. The fatigue fracture in the I region may be quantized by a slow crack growth rate, which is the incline of the graph in the I region represented as following formula (<NUM>).

Wherein v is the crack velocity, v<NUM> is an initial crack velocity, and n is the slow crack growth rate.

The most important factor in deciding whether the crack may grow is a threshold stress intensity factor (Kth), which may be between <NUM>~<NUM>. 27MPa· m<NUM>, corresponding to the <NUM> region of the graph of <FIG>. When the stress intensity factor KI is substantially equal to or less than the threshold stress intensity factor Kth, the crack does not grow, and therefore, the glass does not fail under the static application of stress. In other words, when the glass in bent status has the stress intensity factor KI substantially equal to or less than the threshold stress intensity factor Kth, the slow crack growth in the glass may be reduced or prevented.

According to the formulas (<NUM>) and (<NUM>), the following two different approach may be taken to reduce or prevent the failure of glass in bent status under static and/or dynamic stress: <NUM>) a flawless processing to reduce the size of the flaw imbedded in the glass generated during cutting, chamfering, and treating of the glass; and <NUM>) maintaining the stress intensity under the condition that the fracture or breakage and/or fatigue fracture may not occur by the bending of the glass.

<FIG> is a schematic side view illustrating bending of a conventional glass article <NUM>. When the glass element is bent, the glass element is deformed in a parabolic shape as illustrated in <FIG>, and the applied tensile stress is greatest at the vertex of the parabolic shape, according to the following formula (<NUM>).

Wherein σ is the tensile stress, E is Young's Modulus, t is the thickness of the glass, υ is the Poisson rate, and D is the distance between the <NUM> Point Bending (2PB) plates <NUM>.

<FIG> is a schematic side view illustrating bending of the flexible glass article <NUM> according to the exemplary embodiments. The glass element <NUM> may be chemically strengthened by exchanging sodium ion (Na+) in the glass element with potassium ion (K+) through a Na-K ion exchange reaction. By exchanging the potassium ion (K+) which has relatively bigger size that that of the sodium ion (Na+), the surface compressive stress may be increased in the surface of the glass element. A compressive stress region may be referred to the surface region of the glass element that has the increased compressive stress.

The increased compressive stress formed in the compressive stress region may reduce the actual tensile stress applied at the vertex of the parabolic shape according to following formula (<NUM>), and therefore, the formula (<NUM>) may be rewritten to formula (<NUM>): <MAT> <MAT>.

Wherein σactual is the actual tensile stress, σa is the applied stress, and CSflaw is compressive stress applied at the flaw.

First, an example of the chemically strengthened glass is described when used without the coating <NUM>. To make the chemically strengthened glass having a thickness of <NUM>, and Young's Modulus of <NUM> GPa to have a bend radius of <NUM> (R3), considering a module layer thickness of <NUM>, the chemically strengthened glass needs to be bent until the distance between the 2PB plates <NUM> is <NUM>. According to the formula (<NUM>), the applied tensile stress may be <NUM> MPa. If the glass is chemically strengthened to have the surface compressive stress of <NUM> MPa, a depth of the compressive stress region (DOL) of <NUM>, in order to prevent the fracture or breakage and/or fatigue fracture, the size of the flaw must be maintained between about <NUM> and <NUM>. However, it is practically impossible to use a conventional chemical flaw healing method to control the size of the flaw under <NUM>.

Referring to <FIG> and <FIG>, the glass article <NUM> according to the exemplary embodiments includes the coating <NUM> formed on the glass element <NUM>. The coating <NUM> may have a thickness between about <NUM> and about <NUM>. Exemplary processes for making and applying the coating <NUM> are discussed subsequently.

<FIG> is a schematic sectional view illustrating modification of a neutral axis NA of the flexible glass article <NUM> according to the principles of the invention. The neutral axis NA refers to an axis of the glass article which has zero tensile when the glass article is bent. <FIG> is schematic sectional view illustrating the modified neutral axis ω of the flexible glass article <NUM> according to the exemplary embodiments.

Referring to <FIG>, in response to the thickness and the Young's modulus of the coating <NUM>, the neutral axis NA of the glass article <NUM> is modified to be shifted toward the coating <NUM>. Accordingly, when the glass element is bent with the first surface disposed toward the inside of the bend, the region of the glass element <NUM> that tensile stress is applied may be reduced, and the effective bending radius may be further reduced.

Referring to <FIG>, the modified neutral axis ω of the glass article <NUM> may be calculated according to the following formula (<NUM>): <MAT>
wherein m is the modified neutral axis of the glass article, wi is the neutral axis of the glass element, tc is the thickness of the coating <NUM>, tg is the thickness of the glass element <NUM>, b is a width of the glass article <NUM>, Ec is the Young's modulus of the coating <NUM>, and Eg is the Young's modulus of the glass element <NUM>.

According to the formula (<NUM>), an exemplary coating having a Young's modulus of <NUM> GPa and <NUM> GPa and a thickness between about <NUM> and about <NUM> formed onto the glass element <NUM> having a thickness between about <NUM> and about <NUM>. Since the thickness of the coating is inversely proportional to an effective thickness, the bending radius may be reduced as the thickness of the coating <NUM> is increased. Following Table <NUM> shows the effective thickness of the glass article <NUM> based upon the thickness of the coating <NUM> and the thickness of the glass element <NUM>:
<IMG>.

Accordingly, following Table <NUM> shows the thickness of the coating <NUM> necessary to make the effective thickness of the glass article <NUM> to be about <NUM>:.

Particularly, the glass article <NUM> having the glass element <NUM> with a thickness of <NUM> and the coating <NUM> having a Young's modulus of <NUM> GPa and a thickness of <NUM>, when bent, may have the effective thickness of <NUM>. Thus, the glass article <NUM> may have the same bending characteristics as the glass having a thickness of <NUM>, which may have a bending radius of <NUM>, and therefore, the glass article <NUM> may have the effective bending radius of <NUM> (R1).

Referring to <FIG>, in order to modify the neutral axis NA from the neutral axis of the glass element wi to the modified neutral axis of the glass article ω, the coating <NUM> is formed directly on the glass element <NUM> without intervening adhesive. According to an exemplary embodiment, the coating <NUM> may be formed integrally with the glass element <NUM>.

For example, forming the coating <NUM> directly onto the glass element <NUM> may include following steps:
First, while <FIG> illustrate that the glass article <NUM> includes only one layer of coating <NUM>, the exemplary embodiments are not necessarily limited thereto. The glass article <NUM> may include multiple layers of one or more different types of coatings formed on the glass element. Each of the coatings <NUM> may include a polymer that has an optical characteristic adequate for use as a window, and may be formed on the glass element <NUM>. For example, each of the multiple layers of the coating may include at least one of polyester acrylate and polyimide, and may include different materials in each of the multiple layers.

<FIG> is a flowchart illustrating an exemplary method of manufacturing the glass article according to the principles of the invention. First, a glass element having a first thickness and having first and second surfaces is prepared <NUM>.

The glass element may be chemically strengthening to form a compressive stress region extending from the first surface of the glass element to a first depth in the glass element, with the compressive stress region preferably having a compressive stress of at least about <NUM> MPa at the first surface of the glass element <NUM>. Various methods may be used to chemically strengthen the glass element. For example, the glass element may be chemically strengthened by exchanging sodium ions (Na+) in the glass element with potassium ions (K+) through a Na-K ion exchange reaction. By exchanging the potassium ions (K+), which has relatively bigger size that that of the sodium ion (Na+), the surface compressive stress may be increased in the surface of the glass element. For example, the Na-K ion exchange reaction may be performed by submerged the glass element in potassium nitride (KNO<NUM>) bath.

After the glass element is chemically strengthened, a coating may be formed on the second surface of the glass element, wherein the coating preferably has a second thickness substantially equal to or greater than three times the first thickness <NUM>. Various methods may be used to form the coating directly on the glass element. Forming the coating directly on the glass element includes: applying a coating solution on the second surface of the glass element; applying a soft mold on the coating solution; forming the coating by exposing the glass element to ultraviolet radiation to cure the coating solution; and removing the soft mold. The coating <NUM> becomes a part of the glass article, and therefore, the coating <NUM> has relatively high optical transmittance and resistance to heat. Also, the material is cured by ultraviolet radiation, but the material should not turn yellow by ultraviolet radiation and should not have haze when cured.

For example, the coating solution may include at least one of Poly(methyl methacrylate) PMMA, Polyethylene terephthalate PET, Cellulose triacetate TAC, Polyether sulfone PES, Ethylene tetrafluoroethylene ETFE, Fluorinated ethylene propylene FEP, Perfluoroalkoxy alkane PFA, organic polymer ORGA, Polycarbonate PC , Fiber-reinforced plastic FRP, Polyurethane, Polyester, Polyaramid, Polypropylene PP, Polyethylene naphthalate PEN, and Polyimide.

Furthermore, the coating may be exposed to ultraviolet radiation again after removing the soft mold to further cure the coating <NUM>.

Referring to <FIG>, only one layer of the coating is formed, but the exemplary embodiments are not limited thereto. As noted above, multiple layers of coatings may be formed on the glass element. The method of forming the coatings may be repeated to form the multiple layers of the coating. Each of the coatings <NUM> may include a polymer that has an optical characteristic adequate for use as a window, and may be formed on the glass element <NUM>. For example, each of the multiple layers of the coating may include at least one of polyester acrylate and polyimide, and may include different materials in each of the multiple layers.

<FIG> is a graph illustrating the relationship between the glass thickness and the minimum bending radius according to the exemplary embodiments in contrast with conventional chemically strengthened glass.

Referring to <FIG>, in order to individually use the chemically strengthened glass having increased surface compressive stress to form a R1 glass article, which has a bending radius of <NUM>, the individual chemically strengthened glass needs to have a thickness of <NUM>. Even to form a R3 glass window, which has a bending radius of <NUM>, the individual chemically strengthened glass needs to have a thickness of <NUM>. However, it is practically impossible to reduce the thickness of a glass panel to less than <NUM> using glass etching, which is conventionally used to reduce thickness of glass from between <NUM> and <NUM> to less than <NUM>, because of lack of uniformity.

On the other hand, the glass article <NUM> according to the exemplary embodiments having the glass element <NUM> with greater thickness may have relatively small bending radius. Following Table <NUM> is the calculation of the effective thickness of the glass article <NUM> including the glass element <NUM> having a thickness of about <NUM>, based upon the thickness and the Young's modulus of the coating <NUM>, according to the exemplary embodiments.

According to the Table <NUM>, the neutral axis of the glass article <NUM> may be shifted into the coating <NUM>, and therefore, <NUM> tensile stress may be applied to the glass article <NUM> when the glass article <NUM> is bent with the first surface of the glass article <NUM> disposed toward the inside of the bend. For example, to shift the neutral axis of the glass article <NUM> into the coating <NUM>, the coating <NUM> having a Young's modulus of about <NUM> GPa may have a thickness of at least <NUM> times the thickness of the glass element <NUM> (=<NUM>/<NUM>), and the coating <NUM> having a Young's modulus of about <NUM> GPa may have a thickness of at least <NUM> times the thickness of the glass element <NUM> (=<NUM>/<NUM>). More particularly, the coating <NUM> including polyimide, which has relatively large Young's modulus of about <NUM> GPa, may have a thickness of <NUM> times the thickness of the glass element <NUM>.

Therefore, the coating <NUM> may have a thickness of at least <NUM> times the thickness of glass element <NUM>. Following Table <NUM> shows various test results comparing (a) conventional chemically strengthened glass element used individually and (b) the glass article according to the exemplary embodiments. Both the conventional chemically strengthened glass element and the chemically strengthened glass element <NUM> included in the glass article <NUM> have a thickness of <NUM>, and a compressive stress region having a compressive strength of about <NUM> MPa and the depth (DOL) of about <NUM>. The glass article according to the exemplary embodiments may include a coating <NUM> having a thickness of <NUM> and a Young's modulus of about <NUM> GPa.

According to the test results, the individual glass element failed to pass the <NUM> bending test at the first bending. On the other hand, the glass article according to the exemplary embodiments passed the <NUM> dynamic bending test and the static bending test of <NUM> minutes. Both the individual glass element and the glass article according to the exemplary embodiments have substantially the same optical characteristics.

The shock resistance test may be performed by dropping pen on to test subject. The test subject may be attached to a base film using a pressure sensitive adhesive having a thickness of <NUM> and Young's modulus of about <NUM> MPa. The base film may be attached to a steel plate. The base film may include Polyethylene terephthalate PET having a thickness of <NUM>. The pen used in the test is BIC® ORANGE™ FINE pen, having a point diameter of <NUM> and weight of <NUM>. The drop test is performed by increasing the drop height by <NUM> after the test subject passes the test until the test subject fails. According to the test results, the individual glass element broke at a <NUM> drop, and the glass article according to the exemplary embodiment broke at a <NUM> drop.

<FIG> a schematic side views illustrating exemplary embodiments of the flexible glass article according to the exemplary embodiments.

Referring to <FIG>, the glass article <NUM> may include the glass element <NUM> and the coating <NUM>. The glass elements <NUM> and the coating <NUM> of the glass article <NUM> may be formed of materials substantially same as the glass element <NUM> and the coating <NUM> of the glass article <NUM> illustrated in <FIG>, <FIG>, <FIG>. The lower surface of the coating <NUM> may have patterns. The patterns formed on the lower surface of the coating <NUM> may be formed by including corresponding patterns in the soft mold, which is applied onto the coating solution during the step of forming the coating.

Referring to <FIG>, the glass article <NUM> may include the glass element <NUM> and the coating <NUM>. The glass elements <NUM> and the coating <NUM> of the glass article <NUM> may be formed of materials substantially same as the glass element <NUM> and the coating <NUM> of the glass article <NUM> illustrated in <FIG>, <FIG>, <FIG>. The glass element <NUM> may be partially slimmed by including slimming patterns in the second surface of the glass element <NUM>. The coating <NUM> may be formed to fill the slimming patterns of the glass element <NUM>. The lower surface of the coating <NUM> may be flat.

Referring to <FIG>, the glass article <NUM> may include the glass element <NUM> and the coating <NUM>. The glass elements <NUM> and the coating <NUM> of the glass article <NUM> may be formed of materials substantially same as the glass element <NUM> and the coating <NUM> of the glass article <NUM> illustrated in <FIG>, <FIG>, <FIG>. The glass element <NUM> may be substantially the same as the glass article <NUM> of <FIG>. The coating <NUM> may be formed to fill the slimming patterns of the glass element <NUM>. The lower surface of the coating <NUM> may be flat. The coating <NUM> may also have slimming pattern corresponding to the slimming patterns of the glass element <NUM>. The slimming patterns formed on the lower surface of the coating <NUM> may be formed by including corresponding pattern in the soft mold, which is applied onto the coating solution during forming the coating.

Claim 1:
A flexible glass article, comprising:
a glass element (<NUM>) having a first thickness of <NUM> to <NUM> and including first and second opposed surfaces, and a compressive stress region extending from the first surface of the glass element (<NUM>) to a first depth in the glass element, the compressive stress region having a compressive stress of at least <NUM> MPa at the first surface of the glass element (<NUM>); and
a coating (<NUM>) directly cured by ultraviolet radiation on the second surface of the glass element, wherein the glass article is of an absence of fracture when the glass element (<NUM>) is bent with the first surface disposed toward the inside of the bend and held at a bend radius of <NUM> to <NUM> for at least <NUM> minutes at <NUM> and <NUM> % relative humidity,
characterized in that the coating (<NUM>) has a second thickness equal to or greater than three times the first thickness and the second thickness is equal to or less than <NUM>, and that the coating (<NUM>) has an elastic modulus equal to or less than <NUM> GPa.