Glass article having glass substrate attached to frame with variable thickness adhesive

Abstract

Disclosed are embodiments of a glass article. The glass article includes a glass substrate extending between a first glass edge region and a second glass edge region in a first direction. The glass article also includes a frame having a convex region defining a convex curvature with a first radius of curvature between a first outer frame edge and a second outer frame edge. The convex region is curved along the first direction. An adhesive is disposed between the glass substrate and the convex region of the frame. The adhesive attaches the glass substrate to the frame to conform the glass substrate to the convex curvature. The adhesive includes a continuous layer with variable thickness along the first direction such that a second radius of curvature of the first glass edge region and of the second glass edge region is greater than the first radius of curvature.

Description

GLASS RTICLE HAVING GLASS SUBSTRATE ATTACHED TO FRAME WITH VARIABLE THICKNESS DHESIVECross-reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Application Serial No. 63 / 545,627, filed on October 25, 2023, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND

[0002] The disclosure relates to a glass article and, more particularly, to a glass article having a glass substrate joined to a convexly curved frame with a variable thickness adhesive layer.

[0003] Vehicle interiors include curved surfaces and can incorporate displays in such curved surfaces. The materials used to form such curved surfaces are typically limited to polymers, which do not exhibit the durability and optical performance of glass. As such, curved glass substrates are desirable, especially when used as covers for displays. Existing methods of forming such curved glass substrates, such as hot bending, have drawbacks including high cost, optical distortion, and surface marking. Other low-temperature methods of forming such curved glass substrates may experience issues related to adhesive failure, especially for convexly curved parts. In particular, the glass substrate is elastically deformed at low temperatures and, as a result, the glass substrate remains stressed during its operating lifetime, which creates additional stress on the adhesive.SUMMARY

[0004] According to an aspect, embodiments of the disclosure relate to a glass article. The glass article includes a glass substrate comprising a first major surface and a second major surface. The second major surface is opposite to the first major surface. The first major surface and the second major surface extend between a first glass edge region and a second glass edge region in a first direction. The glass article also includes a frame comprising a frame surface. The frame surface comprises a convex region defining a convex curvature between a first outer frame edge and a second outer frame edge. The convex curvature comprises a first maximum radius of curvature that is less than or equal to 10,000 mm. The convex region is curved along the first direction. An adhesive is disposed between the glass substrate and the convex region of the frame surface. The adhesive attaches the second major surface of the glass substrate tothe frame surface to hold the glass substrate in an elastically deformed state to conform the glass substrate to the convex curvature comprising the first radius of curvature in an area between the first glass edge region and the second glass edge region. The adhesive comprises a first region extending inward from the first outer frame edge along the first direction and a second region extending inward from the second outer frame edge along the first direction. In each of the first region and the second region, the adhesive comprises a continuous layer with variable thickness along the first direction such that a second radius of curvature of the first glass edge region and of the second glass edge region is greater than the first radius of curvature.

[0005] According to another aspect, embodiments of the disclosure relate to a glass article. The glass article comprises a frame comprising a convex region curved along a first direction to define a convex curvature extending between a first outer frame edge and a second outer frame edge. The glass article also comprises a glass substrate. An adhesive is disposed between the frame and the glass substrate. The adhesive joins the glass substrate to the frame to hold the glass substrate in an elastically deformed state to conform the glass substrate to the convex curvature. The adhesive increases in volume toward the first outer frame edge and toward the second outer frame edge such that the glass substrate defines flat tip regions proximal to the first outer frame edge and the second outer frame edge.

[0006] According to still another aspect, embodiments of the disclosure relate to a method. In the method, a glass substrate is formed over a mold at a temperature of 200 °C or less. The mold defines a concave curvature having a first region with a first radius of curvature disposed between second regions each having a second radius of curvature that is greater than the first radius of curvature. The glass substrate comprises a central portion that conforms to the first radius of curvature and edge regions that conform to the second radius of curvature. A frame is attached to the glass substrate using an adhesive. The frame comprises a convex curvature with a third radius of curvature that matches the first radius of curvature. The convex curvature extends from a first outer frame edge to a second outer frame edge. The adhesive maintains the glass substrate in an elastically deformed state against the frame, and the adhesive increases in volume towards the edge regions of the glass substrate.

[0007] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0008] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a perspective view of a vehicle interior with vehicle interior systems, according to exemplary embodiments.

[0010] FIG. 2 depicts a glass article having a variable thickness adhesive layer, according to exemplary embodiments.

[0011] FIG. 3 depicts a glass substrate of the glass article, according to exemplary embodiments.

[0012] FIG. 4 depicts a convexly curved frame, according to exemplary embodiments.

[0013] FIG. 5 depicts an exploded view of the glass article having a variable thickness adhesive, according to exemplary embodiments.

[0014] FIG. 6 depicts a detail view of a variable thickness portion of the adhesive of the glass article, according to exemplary embodiments.

[0015] FIG. 7 depicts a detail view of a uniform thickness portion of the adhesive of the glass article, according to exemplary embodiments.

[0016] FIG. 8 depicts steps of a method for forming the glass article, according to exemplary embodiments.

[0017] FIG. 9 depicts the relationship between uniform thickness portion of the adhesive and the additional adhesive of the variable thickness portion of the adhesive, according to exemplary embodiments.

[0018] FIG. 10 depicts a graph of maximum principal stress in the adhesive layer for glass articles without a flat tip region and for glass articles having a flat tip region created by the additional adhesive in the variable thickness region of adhesive, according to exemplary embodiments.

[0019] FIG. 11 depicts a graph of additional adhesive in the variable thickness region for various bezel widths and radii of curvature, according to an exemplary embodiment.DETAILED DESCRIPTION

[0020] Reference will now be made in detail to various embodiments of a convexly curved glass article having a variable thickness adhesive layer, examples of which are illustrated in the accompanying drawings. The glass article includes a glass substrate cold-bent in an elastically deformed state and adhered to a frame. In existing cold-bent, convexly curved glass articles, the elastic bending stress at the edges of the glass substrate causes the glass substrate to pull away from the frame, leading to failure of the adhesive and delamination in certain circumstances. According to the present disclosure, the adhesive is thicker at the edges of the glass substrate in the direction of the curvature, which decreases the elastic bending stress at the edges. In this way, the glass substrate has flat tip edge regions with reduced stress (as compared to certain existing implementations with an adhesive layer of uniform thickness) on the adhesive holding the glass substrate to the frame. While providing a marked improvement in reliability, the increase in adhesive thickness is substantially undetectable to the human eye. That is, the increase in adhesive thickness at the edge of the glass substrate to produce the flat tip region may be 0.20 mm or less for a radius of curvature as tight as 400 mm. These and other aspects and advantages will be described in relation to the embodiments provided below and in the drawings. These embodiments are presented by way of example and not by way of limitation.

[0021] In order to provide context for the glass article and the process of forming the glass article described herein, exemplary embodiments of curved glass articles will be described in relation to the particular application of a vehicle interior system.

[0022] FIG. 1 shows an exemplary interior 10 of a vehicle that includes three different embodiments of vehicle interior systems 20, 30, 40. Vehicle interior system 20 includes a base, shown as center console base 22, with a curved surface 24 including a display 26. Vehicle interior system 30 includes a base, shown as dashboard base 32, with a curved surface 34 including a display 36. The dashboard base 32 typically includes an instrument panel 38 which may also include a display. Vehicle interior system 40 includes a base, shown as steering wheel base 42, with a curved surface 44 and a display 46. In one or more embodiments, the vehicle interior system includes a base that is an arm rest, a pillar, a seat back, a floorboard, a headrest, a door panel, or any portion of the interior of a vehicle that includes a curved or flat surface.

[0023] The embodiments of the glass articles described herein can be used in each of vehicle interior systems 20, 30, 40, among others. In one or more such embodiments, the glass article discussed herein may include a cover glass substrate that also covers non-display surfaces of the dashboard, center console, steering wheel, door panel, etc. In such embodiments, the glass material may be selected based on its weight, aesthetic appearance, etc. and may be provided with a coating (e.g., an ink or pigment coating) including a pattern (e.g., a brushed metal appearance, a wood grain appearance, a leather appearance, a colored appearance, etc.) to visually match the glass components with adjacent non-glass components. In specific embodiments, such ink or pigment coating may have a transparency level that provides for deadfront or color matching functionality when the display 26, 36, 38, 46 is inactive. Further, while the vehicle interior of FIG. 1 depicts a vehicle in the form of an automobile (e.g., cars, trucks, buses and the like), the glass articles disclosed herein can be incorporated into other vehicles, such as trains, sea craft (boats, ships, submarines, and the like), aircraft (e.g., drones, airplanes, jets, helicopters and the like), and spacecraft.

[0024] FIG. 2 depicts an embodiment of a glass article 50 that can be used in vehicle interior systems 20, 30, 40. The glass article 50 comprises a glass substrate 52, a frame 54, and an adhesive 56. The adhesive 56 is disposed between the glass substrate 52 and the frame 54.

[0025] The glass substrate 52 comprises a first major surface 58 and a second major surface 60. The second major surface 60 is opposite to the first major surface 58. In one or more embodiments, the first major surface 58 and the second major surface 60 define a thickness T of the glass substrate 52. In one or more embodiments, the thickness T is 2 mm or less. In one or more embodiments, the thickness T is in a range of 0.3 mm to 2 mm, in particular in a range of 0.5 mm to 1.1 mm. A minor surface 62 extends between the first major surface 58 and the second major surface 60 and around a periphery of the glass substrate 52.

[0026] FIG. 3 depicts an embodiment of a glass substrate 52 as viewed from the second major surface 60. As can be seen in FIG. 3, the glass substrate 52 comprises a plurality of glass edge regions, including a first glass edge region 64a, a second glass edge region 64b, a third glass edge region 64c, and a fourth glass edge region 64d. In one or more embodiments, the glass substrate 52 extends between the first glass edge region 64a and the second glass edge region 64b in a first direction 66 and between the third glass edge region 64c and the fourth glass edge region 64d in a second direction 68. In one or more embodiments, the first direction 66 is perpendicular to the second direction 68.

[0027] FIG. 4 depicts an embodiment of the frame 54. As can be seen in FIG. 4, the frame 54 comprises a frame surface 70. The frame surface 70 comprises a convex region 72 defining a convex curvature 74 between a first outer frame edge 76a and a second outer frame edge 76b. In one or more embodiments, the frame surface 70 may comprise other flat or curved regions, adjacent to the convex region. For example, the convex region 72 may be adjacent a flat region having no curvature (i.e., a radius of curvature of> 10,000 mm) or may be adjacent to a concave region, which may (together with the convex region 72) define an S-shaped frame surface. Other frame surface shapes comprised of at least one convex region 72 and at least one of a flat or curved region may also be defined. Alternatively, as shown in FIG. 2, the frame surface 70 may consist of just one continuous convex region 72.

[0028] Further, in one or more embodiments, the frame 54 includes a third outer frame edge 76c and a fourth outer frame edge 76d. The third outer frame edge 76c connects a first end of the first outer frame edge 76a to a first end of the outer second frame edge 76b, and the fourth outer frame edge 76 connects a second end of the first outer frame edge 76a to a second end of the second outer frame edge 76b. In one or more embodiments, frame 54 includes corresponding inner frame edges 77a-d, and the frame surface 70 is defined by the space between the inner frame edges 77a-d and the outer frame edges 76a-d. In one or more such embodiments, the inner frame edges 77a-d and outer frame edges 77a-d define a bezel 78 that extends around the perimeter of the frame 54, and the bezel 78 surrounds an opening 80. The opening 80 may accommodate a display module attached to the second major surface 60 of the glass substrate 52. In one or more embodiments, the bezel 78 comprises a width W of 3 mm to 12 mm in which the width W is defined as a distance measured perpendicularly between an outer frame edge 76a-d and a corresponding inner frame edge 77a-d. For example, the width W of the bezel 78 may be in a range from 3 mm to 12 mm as measured between the first outer frame edge 76a and the first inner frame edge 77a. In one or more embodiments, the width W of the bezel 78 as measured between the first outer frame edge 76a and the first inner frame edge 77a is the same as the width W of the bezel 78 as measured between the second outer frame edge 76a and the second inner frame edge 77a. In one or more embodiments, the width W of the bezel 78 as measured between the third outer frame edge 76a and the third inner frame edge 77a is the same as the width W of the bezel 78 measured between the fourth outer frame edge 76d and the fourth inner frame edge 77d. Alternatively, in one or more embodiments, the width W of the bezel 78 as measured between any outer frame edge 76a-d and corresponding inner frame edge 77a-d may be the same or different than the width W of the bezel 78 asmeasured between any other outer frame edge 76a-d and corresponding inner frame edge 77a- d.

[0029] In one or more embodiments, the convex curvature 74 of the convex region 72 comprises a first maximum radius of curvature R1 that is less than or equal to 10,000 mm. In one or more embodiments, the first maximum radius of curvature R1 is in a range from 400 mm to 3000 mm. As can be seen in FIG. 4, the convex region 72 is curved along the first direction 66.

[0030] FIG. 5 provides an exploded view of the glass article 50. The adhesive 56 is disposed between the glass substrate 52 and at least the convex region 72 of the frame surface 70, and the adhesive 56 attaches the second major surface 60 of the glass substrate 52 to the frame surface 70 to hold the glass substrate 52 in an elastically deformed state. In the elastically deformed state, the glass substrate 52 conforms to the convex curvature 74 such that the first major surface 58 adopts the first radius of curvature R1 in an area between the first glass edge region 64a and the second glass edge region 64b. The adhesive 56 comprises a first region 82a extending inward from the first frame edge 76a along the first direction 66 and a second region 82b extending inward from the second frame edge 76b along the first direction 66. In each of the first region 82a and the second region 82b, the adhesive 56 comprises a continuous layer with variable thickness along the first direction 66 such that a second radius of curvature R2 of the first glass edge region 64a and of the second glass edge region 64b is greater than the first radius of curvature Rl. In one or more embodiments, the second radius of curvature is greater than 5000 mm. In one or more particular embodiments, the glass substrate 52 defines flat tip regions 84 proximal to the first frame edge 76a and the second frame edge 76b. By “flat tip region,” it is meant that the second radius of curvature R2 in the first glass edge region 64a and in the second glass edge region 64b approach flatness or are flat (i.e., a radius of curvature of >10,000 mm).

[0031] FIG. 6 depicts a cross-sectional, detailed view of the first glass edge region 64a, which is also representative of the second glass edge region 64b. In one or more embodiments, the first region 82a comprises a uniform thickness region 86 and a variable thickness region 88. In one or more such embodiments, the variable thickness region 88 extends from the uniform thickness region 86 to the first outer frame edge 76a. In one or more embodiments, the uniform thickness region 86 extends from the first inner frame edge 77a outwardly to the variable thickness region 88. In one or more other embodiments, the uniform thickness region 86 extends to the variable thickness region 88 from a location outward of the first inner frameedge 77a. In one or more embodiments, the variable thickness region 88 extends from the first outer frame edge 76a to the first inner frame edge 77a such that the variable thickness region 88 extends the entire width W of the bezel 78 (as shown in FIG. 4). In such embodiments, the uniform thickness region 86 may exist only between the frame surface 70 and the third glass edge region 64c and between the frame surface 70 and the fourth glass edge region 64d. In one or more embodiments, the variable thickness region 88 may not extend all the way out to the first outer frame edge 76a, but may instead include an outer boundary that is disposed inward of the first outer frame edge 76a.

[0032] In one or more embodiments, the uniform thickness region 86 comprises a first average thickness Tu, and the variable thickness region 88 comprises a second average thickness Tv at the respective outer frame edge 76a-d (or at the location of the maximum average thickness if not at the outer frame edge 76a-d). The second average thickness Tv is at least 0.01 mm greater than the first average thickness Tu. In one or more embodiments, the second average thickness Tv is up to 0.20 mm greater than the first average thickness Tu. In one or more embodiments, the first average thickness Tu is in a range from 0.3 mm to 1.3 mm.

[0033] Similarly, though not shown in FIG. 6, the second region 82b may comprise a uniform thickness region 86 and a variable thickness region 88 in which the variable thickness region 88 extends from the uniform thickness region 86 to the second frame edge 76b as described in relation to the first region 82a.

[0034] In one or more embodiments, in the first region 82a and the second region 82b, a volume of adhesive 56 may be described as increasing toward the first frame edge 76a and toward the second frame edge 76b. That is, with increasing distance from a nearest inner frame edge 77a, 77b in a direction perpendicular to that inner edge 77a, 77b, the volume of adhesive 56 per 100 pm interval of lateral distance may increase.

[0035] FIG. 7 depicts a cross-sectional, detailed view of the third glass edge region 64c and the third frame edge 76c. In one or more embodiments, the adhesive 56 disposed between the third glass edge region 64c of glass substrate 52 and the third frame edge 64c has a uniform thickness. That is, the thickness of the adhesive 56 may not substantially change in a direction perpendicular to the third frame edge 76c since there is no curvature along that particular direction. However, embodiments are also envisioned where the adhesive 56 comprises a nonuniform thickness in the third glass edge region 64c (and fourth glass edge region 64d) if there is curvature along a direction perpendicular to the third outer frame edge 76c (and fourthouter frame edge). For example, the frame 54 could be complexly curved and, in addition to the curvature depicted FIG. 4, could also be curved along an axis of curvature perpendicular to that depicted.

[0036] Having described the structure of the glass article 50, a method 100 of making the glass article 50 will be described in relation to FIG. 8. In a first step 101 of the method 100, a glass substrate 52 is elastically formed over a mold 110 at a temperature of 200 °C or less. In one or more embodiments, the temperature is 150 °C or less, 100 °C or less, 50 °C or less, or at room temperature. Such temperatures are below the softening point of the glass substrate 52, and because the glass substrate 52 is elastically deformed at temperatures below the softening point, the process may be described as “cold-bending.” An example of such a process is the ColdForm™ process performed by Coming Incorporated, Coming, NY. Forming at or above the softening point may be referred to as “hot-bending.” As compared to hot-bending, coldbending requires less energy and results in less optical distortions. Additionally, decorative and functional coatings can more easily be applied to the glass substrate 52 in a flat state, and upon bending, the coatings do not degrade or rupture as a result of the temperature required for hot-bending.

[0037] As shown in the first step 101 of FIG. 8, the mold 110 comprises a forming surface 112 defining a concave curvature 114. The concave curvature 114 has a first region 116 with a first radius of curvature R1 disposed between second regions 118 that each have a second radius of curvature R2. The second radius of curvature R2 is greater than the first radius of curvature Rl. The first major surface 58 of the glass substrate 52 is pressed against the forming surface 112 such that a central portion 120 of the glass substrate 52 conforms to the first radius of curvature Rl. Further, first and second glass edge regions 64a, 64b of the glass substrate 52 conform to the second radius of curvature R2.

[0038] In one or more embodiments, the method 100 further includes a second step 102 of holding the glass substrate 52 into conformity with the forming surface 112, for example using vacuum pressure. As can be seen in FIG. 8, the mold 110 includes a plurality of vacuum channels 122 in communication with the forming surface 112. Vacuum is drawn through the vacuum channels 122 to hold the glass substrate 52 against the forming surface 112 using suction.

[0039] In a third step 103 of the method 100, the frame 54 is attached to the glass substrate 52 using the adhesive 56. In one or more embodiments, the adhesive 56 is applied first to the glasssubstrate 52, and the frame 54 is brought into contact with the adhesive 56. In one or more other embodiments, the adhesive 56 is applied first to the frame 54, and the frame 54 bearing the adhesive 56 is brought into contact with the glass substrate 52. During this third step 103, achieving the desired spacing between the glass substrate 52 and the frame 54 to produce the variable thickness of the adhesive 56 may be facilitated using a plurality of spacers 124. In particular, the spacers 124 may help to ensure that the adhesive 56 is not accidentally squeezed out from between the glass substrate 52 and frame 54 when producing the flat tip regions.

[0040] As shown in the third step 103 of FIG. 8, the frame surface 70 of the frame 54 comprises a convex curvature 74 with a third radius of curvature R3 that matches the first radius of curvature R1 (in particular matching the first radius of curvature R1 within 10%, more particularly within 5%, and most particularly within 2%). As discussed above, the frame surface 70 of the frame 54 may have a convex curvature 74 defining a single, continuous curvature with the third radius of curvature R3.

[0041] In one or more embodiments, the glass article 50 remains in the mold 110 until the adhesive 56 cures (or at least cures sufficiently) to maintain the glass substrate 52 in an elastically deformed state against the frame 54. Thereafter, in a fourth step 104, the vacuum pressure is removed, and the glass article 50 is removed from the mold 110.

[0042] Returning to FIG. 3, additional structural details of glass substrate 52 are shown and described. As noted above, glass substrate 52 has a thickness T that is substantially constant and is defined as a distance between the first major surface 58 and the second major surface 60. In various embodiments, T may refer to an average thickness or a maximum thickness of the glass substrate. In addition, glass substrate 52 includes a width W defined as a first maximum dimension of one of the first or second major surfaces 58, 60 orthogonal to the thickness T, and a length L defined as a second maximum dimension of one of the first or second major surfaces 58, 60 orthogonal to both the thickness and the width. In other embodiments, W and L may be the average width and the average length of glass substrate 52, respectively.

[0043] In various embodiments, average or maximum thickness T is in the range of 0.3 mm to 2 mm. In various embodiments, width W is in a range from 5 cm to 250 cm, and length L is in a range from about 5 cm to about 1500 cm.

[0044] In embodiments, the glass substrate 52 may be strengthened. In one or more embodiments, glass substrate 52 may be strengthened to include compressive stress thatextends from a surface to a depth of compression (DOC). The compressive stress regions are balanced by a central portion exhibiting a tensile stress. At the DOC, the stress crosses from a compressive stress to a tensile stress.

[0045] In various embodiments, glass substrate 52 may be strengthened mechanically by utilizing a mismatch of the coefficient of thermal expansion between portions of the article to create a compressive stress region and a central region exhibiting a tensile stress. In some embodiments, the glass substrate may be strengthened thermally by heating the glass to a temperature above the glass transition point and then rapidly quenching.

[0046] In various embodiments, glass substrate 52 may be chemically strengthened by ion exchange. In the ion exchange process, ions at or near the surface of the glass substrate are replaced by - or exchanged with - larger ions having the same valence or oxidation state. In those embodiments in which the glass substrate comprises an alkali aluminosilicate glass, ions in the surface layer of the article and the larger ions are monovalent alkali metal cations, such as Li+, Na+, K+, Rb+, and Cs+. Alternatively, monovalent cations in the surface layer may be replaced with monovalent cations other than alkali metal cations, such as Ag+or the like. In such embodiments, the monovalent ions (or cations) exchanged into the glass substrate generate a stress.

[0047] Ion exchange processes are typically carried out by immersing a glass substrate in a molten salt bath (or two or more molten salt baths) containing the larger ions to be exchanged with the smaller ions in the glass substrate. It should be noted that aqueous salt baths may also be utilized. In addition, the composition of the bath(s) may include more than one type of larger ions (e.g., Na+ and K+) or a single larger ion. 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 glass substrate in a salt bath (or baths), use of multiple salt baths, additional steps such as annealing, washing, and the like, are generally determined by the composition of the glass substrate (including the structure of the article and any crystalline phases present) and the desired DOC and CS of the glass substrate that results from strengthening. Exemplary molten bath compositions may include nitrates, sulfates, and chlorides of the larger alkali metal ion. Typical nitrates include KNO3, NaNO.v LiNO.v NaSOr and combinations thereof. 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 100 hours depending on glass substrate thickness, bathtemperature and glass (or monovalent ion) diffusivity. However, temperatures and immersion times different from those described above may also be used.

[0048] In one or more embodiments, the glass substrate 52 may be immersed in a molten salt bath of 100% NaNOs, 100% KNO3, or a combination of NaNCh and KNO3 having a temperature from about 370 °C to about 480 °C. In some embodiments, the glass substrate may be immersed in a molten mixed salt bath including from about 5% to about 90% KNO3 and from about 10% to about 95% NaNC . In one or more embodiments, the glass substrate may be immersed in a second bath, after immersion in a first bath. The first and second baths may have different compositions and / or temperatures from one another. The immersion times in the first and second baths may vary. For example, immersion in the first bath may be longer than the immersion in the second bath.

[0049] In one or more embodiments, the glass substrate may be immersed in a molten, mixed salt bath including NaNCh and KNO3 (e.g., 49% / 51%, 50% / 50%, 51% / 49%) having a temperature less than about 420 °C (e.g., about 400 °C or about 380 °C), for less than about 5 hours, or even about 4 hours or less.

[0050] Ion exchange conditions can be tailored to provide a “spike” or to increase the slope of the stress profile at or near the surface of the resulting glass substrate. The spike may result in a greater surface CS value. This spike can be achieved by a single bath or multiple baths, with the bath(s) having a single composition or mixed composition, due to the unique properties of the glass compositions used in the glass substrates described herein.

[0051] In one or more embodiments, where more than one monovalent ion is exchanged into the glass substrate, the different monovalent ions may exchange to different depths within the glass substrate (and generate different magnitudes stresses within the glass substrate at different depths). The resulting relative depths of the stress-generating ions can be determined and cause different characteristics of the stress profile.

[0052] CS is measured using those means known in the art, such as by surface stress meter (FSM) using commercially available instruments such as the FSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. SOC in turn is measured by those methods that are known in the art, such as fiber and four-point bend methods, both of which are described in ASTM standard C770-98 (2013), entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient,” thecontents of which are incorporated herein by reference in their entirety, and a bulk cylinder method. As used herein CS may be the “maximum compressive stress” which is the highest compressive stress value measured within the compressive stress layer. In some embodiments, the maximum compressive stress is located at the surface of the glass substrate. In other embodiments, the maximum compressive stress may occur at a depth below the surface, giving the compressive profde the appearance of a “buried peak.”

[0053] DOC may be measured by FSM or by a scattered light polariscope (SCALP) (such as the SCALP-04 scattered light polariscope available from GlasStress Ltd., located in Tallinn, Estonia), depending on the strengthening method and conditions. When the glass substrate is chemically strengthened by an ion exchange treatment, FSM or SCALP may be used depending on which ion is exchanged into the glass substrate. Where the stress in the glass substrate is generated by exchanging potassium ions into the glass substrate, FSM is used to measure DOC. Where the stress is generated by exchanging sodium ions into the glass substrate, SCALP is used to measure DOC. Where the stress in the glass substrate is generated by exchanging both potassium and sodium ions into the glass, the DOC is measured by SCALP, since it is believed the exchange depth of sodium indicates the DOC and the exchange depth of potassium ions indicates a change in the magnitude of the compressive stress (but not the change in stress from compressive to tensile); the exchange depth of potassium ions in such glass substrates is measured by FSM. Central tension or CT is the maximum tensile stress and is measured by SCALP.

[0054] In one or more embodiments, the glass substrate may be strengthened to exhibit a DOC that is described as a fraction of the thickness T of the glass substrate (as described herein). For example, in one or more embodiments, the DOC may be in the range of about 0.05T to about 0.25T. In some instances, the DOC may be in the range of about 20 pm to about 300 pm. In one or more embodiments, the strengthened glass substrate 52 may have a CS (which may be found at the surface or a depth within the glass substrate) of about 200 MPa or greater, about 500 MPa or greater, or about 1050 MPa or greater. In one or more embodiments, the strengthened glass substrate may have a maximum tensile stress or central tension (CT) in the range of about 20 MPa to about 100 MPa.

[0055] Suitable glass compositions for use as glass substrate 52 include soda lime glass, aluminosilicate glass, borosilicate glass, boroaluminosilicate glass, alkali-containing aluminosilicate glass, alkali-containing borosilicate glass, and alkali-containing boroaluminosilicate glass.

[0056] Unless otherwise specified, the glass compositions disclosed herein are described in mole percent (mol%) as analyzed on an oxide basis.

[0057] In one or more embodiments, the glass composition may include S i O2 in an amount in a range from about 66 mol% to about 80 mol%. In one or more embodiments, the glass composition includes AI2O3 in an amount of about 3 mol%to about 15 mol%. In one or more embodiments, the glass article is described as an aluminosilicate glass article or including an aluminosilicate glass composition. In such embodiments, the glass composition or article formed therefrom includes SiCh and AI2O3 and is not a soda lime silicate glass.

[0058] In one or more embodiments, the glass composition comprises B2O3 in an amount in the range of about 0.01 mol% to about 5 mol%. However, in one or more embodiments, the glass composition is substantially free of B2O3. As used herein, the phrase “substantially free” with respect to the components of the composition means that the component is not actively or intentionally added to the composition during initial batching, but may be present as an impurity in an amount less than about 0.001 mol%.

[0059] In one or more embodiments, the glass composition optionally comprises P2O5 in an amount of about 0.01 mol% to 2 mol%. In one or more embodiments, the glass composition is substantially free of P2O5.

[0060] In one or more embodiments, the glass composition may include a total amount of R2O (which is the total amount of alkali metal oxide such as Li2O, Na2O, K2O, Rb2O, and CS2O) that is in a range from about 8 mol% to about 20 mol%. In one or more embodiments, the glass composition may be substantially free of Rb2O, CS2O or both Rb2O and CS2O. In one or more embodiments, the R2O may include the total amount of Li2O, Na2O and K2O only. In one or more embodiments, the glass composition may comprise at least one alkali metal oxide selected from Li2O, Na2O and K2O, wherein the alkali metal oxide is present in an amount greater than about 8 mol% or greater.

[0061] In one or more embodiments, the glass composition comprises Na2O in an amount in a range from about from about 8 mol% to about 20 mol%. In one or more embodiments, the glass composition includes K2O in an amount in a range from about 0 mol% to about 4 mol%. In one or more embodiments, the glass composition may be substantially free of K2O. In one or more embodiments, the glass composition is substantially free of Li2O. In one or more embodiments, the amount of Na2O in the composition may be greater than the amount of Li2O. In some instances, the amount of Na2O may be greater than the combined amount of Li2O andK2O. In one or more alternative embodiments, the amount of Li2O in the composition may be greater than the amount of Na20 or the combined amount ofNa2O and K2O.

[0062] In one or more embodiments, the glass composition may include a total amount of RO (which is the total amount of alkaline earth metal oxide such as CaO, MgO, BaO, ZnO and SrO) in a range from about 0 mol% to about 2 mol%. In one or more embodiments, the glass composition includes CaO in an amount less than about 1 mol%. In one or more embodiments, the glass composition is substantially free of CaO. In some embodiments, the glass composition comprises MgO in an amount from about 0 mol% to about 7 mol%.

[0063] In one or more embodiments, the glass composition comprises ZrO2 in an amount equal to or less than about 0.2 mol%. In one or more embodiments, the glass composition comprises SnCF in an amount equal to or less than about 0.2 mol%.

[0064] In one or more embodiments, the glass composition may include an oxide that imparts a color or tint to the glass articles. In some embodiments, the glass composition includes an oxide that prevents discoloration of the glass article when the glass article is exposed to ultraviolet radiation. Examples of such oxides include, without limitation oxides of: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, W, and Mo.

[0065] In one or more embodiments, the glass composition includes Fe expressed as Fe20s, wherein Fe is present in an amount up to 1 mol%. Where the glass composition includes TiCh. TiCF may be present in an amount of about 5 mol% or less.

[0066] An exemplary glass composition includes Si O2 in an amount in a range from about 65 mol% to about 75 mol%, AI2O3 in an amount in a range from about 8 mol% to about 14 mol%, Na2O in an amount in a range from about 12 mol% to about 17 mol%, K2O in an amount in a range of about 0 mol% to about 0.2 mol%, and MgO in an amount in a range from about 1.5 mol% to about 6 mol%. Optionally, SnO2 may be included in the amounts otherwise disclosed herein. It should be understood, that while the preceding glass composition paragraphs express approximate ranges, in other embodiments, glass substrate 52 may be made from any glass composition falling with any one of the exact numerical ranges discussed above.

[0067] SIMULATED EXAMPLES

[0068] Example glass articles 50 were modeled using finite element analysis based on a construction including a AutoGrade™ Gorilla® glass substrate 52 having a thickness of 1.1 mm, polyurethane adhesive 56 (Betamate™ 2810 SV available from DuPont de Nemours, Inc., Wilmington, DE) in which the uniformly thick portion was 1 mm thick, and an aluminum frame54 having a convex curvature 74 with a radius of curvature R1 of 400 mm. In a first modeled example, the frame 54 had a bezel 78 with a width W of 3 mm, and in a second modeled example, the frame 54 had a bezel 78 with a width W of 9 mm. For the comparative examples, the adhesive was uniformly thick, and the glass substrate did not have flat tip regions. For the examples according to the present disclosure, the first modeled example included adhesive with a variable thickness with a maximum thickness that was 0.01 mm greater than the uniform thickness, and the variable thickness region extended across the entire width of the bezel from the inner frame edge to the outer frame edge. The difference between the uniform thickness and the maximum variable thickness is referred to as the “additional adhesive,” and the formula for calculating the additional adhesive thickness is

[0069] in which 5 is thickness the additional adhesive, x is the length of the flat tip region, and R1 is the radius of curvature of the convexly curved frame. The relationship between the variables is depicted in FIG. 9. The second modeled example had an additional adhesive thickness of 0. 1 mm.

[0070] Comparing the frames with the 3 mm bezels, the maximum principal stress at room temperature (23 °C) experienced using the variable thickness adhesive was reduced by 2.6% relative to the maximum principal stress experienced using the uniform thickness adhesive. Comparing the frames with the 9 mm bezels, the maximum principal stress at room temperature experienced using the variable thickness adhesive was reduced by 24% relative to the maximum principal stress experienced using the uniform thickness adhesive. Advantageously, the decrease in maximum principal stress can be the difference between a passing and a failing part in reliability evaluations, especially when considering a safety factor. Further, using a probabilistic analysis, the failure probability could drop significantly depending on the particular relationship between the stress condition and mechanism of failure.

[0071] FIG. 10 provides a graph of maximum principal stress for bezels having a width of 3 mm to 9 mm. The graph compares the maximum principal stress for uniform thickness adhesive (no flat tip) and for variable thickness adhesive (flat tip). As can be seen in FIG. 10, the maximum principal stress is less for each bezel width when the glass terminates in a flat tip as compared to without a flat tip.

[0072] The reduction in maximum principal stress for a glass substrate with a flat tip region as compared to one without was also investigated in relation to temperature. For a glass substrate with a thickness of 0.7 mm and for a frame with a bezel width of 3 mm, the reduction in maximum principal stress for the adhesive was about 5% at room temperature and at 95 °C, and at -40 °C, the reduction in maximum principal stress was even greater at about 9%. At a bezel width of 8 mm, the reduction in maximum principal stress at -40 °C and at 95 °C was about the same at about 19-20%, and at room temperature, the reduction in maximum principal stress was about 36%.

[0073] For a glass substrate with a thickness of 1. 1 mm and for a frame having a bezel width of 3 mm to 9 mm, the reduction in maximum principal stress was greatest at -40 °C. In particular, the reduction in maximum principal stress was about 7% at 3 mm and as high as about 32% at 8 mm. At room temperature and at 95 °C, the reduction in maximum principal stress was between about 4% and about 10% up to a bezel width of 8 mm, and for a bezel width of 9 mm, the reduction in maximum principal stress at room temperature was about 24% and at 95 °C was about 18%.

[0074] Thus, the benefits of the flat tip region extend across the potential operating range of the glass article when provided as part of a vehicle interior system.

[0075] FIG. 11 provides a graph of additional adhesive thickness (5) for various bezel widths from 3 mm to 12 mm and for various radii of curvature (400 mm to 3000 mm). As can be seen in FIG. 11, the amount of additional adhesive thickness needed to provide a flat tip region for cold-bent glass substrates having a radius of curvature of 1000 mm or more is less than 0. 1 mm up to a bezel width of 12 mm. Thus, as discussed above, only a relatively small amount of adhesive is needed to provide significant decreases in maximum principal stress in the adhesive. Further, even for a radius of curvature as tight as 400 mm, less than 0.2 mm of additional adhesive thickness is needed to produce the flat tip for the glass substrate.

[0076] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article "a" is intended to include one or more than one component or element, and is not intended to be construed as meaning only one.

[0077] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A glass article, comprising: a glass substrate comprising a first major surface and a second major surface, the second major surface being opposite to the first major surface, the first major surface and the second major surface extending between a first glass edge region and a second glass edge region in a first direction; a frame comprising a frame surface, the frame surface comprising a convex region defining a convex curvature between a first outer frame edge and a second outer frame edge, the convex curvature comprising a first radius of curvature that is less than or equal to 10,000 mm, wherein the convex region is curved along the first direction; and an adhesive disposed between the glass substrate and the convex region of the frame surface, the adhesive attaching the second major surface of the glass substrate to the frame surface to hold the glass substrate in an elastically deformed state to conform the glass substrate to the convex curvature having the first radius of curvature in an area between the first glass edge region and the second glass edge region; wherein the adhesive comprises a first region extending inward from the first outer frame edge along the first direction and a second region extending inward from the second outer frame edge along the first direction; and wherein, in each of the first region and the second region, the adhesive comprises a continuous layer with variable thickness along the first direction such that a second radius of curvature of the first glass edge region and of the second glass edge region is greater than the first radius of curvature.

2. The glass article of claim 1, wherein the first region and the second region each comprise a uniform thickness region and a variable thickness region, wherein the variable thickness region extends from the uniform thickness region to the first outer frame edge and the second outer frame edge, respectively.

3. The glass article of claim 2, wherein the uniform thickness region comprises a first average thickness, wherein the variable thickness region comprises a second average thickness at the first outer frame edge and the second outer frame edge, respectively, andwherein the second average thickness is at least 0.01 mm greater than the first average thickness.

4. The glass article of claim 3, wherein the first average thickness is in a range from 0.3 mm to 1.3 mm.

5. The glass article of any one of claims 1-4, wherein in the first region and the second region, a volume of adhesive increases toward the first outer frame edge and toward the second outer frame edge.

6. The glass article of any one of claims 1-5, wherein the frame comprises bezel extending around a perimeter of the frame, wherein the bezel extends from a first inner frame edge to the first outer frame edge and from a second inner frame edge to the second outer frame edge, and wherein each of a first distance measured perpendicularly between the first inner frame edge and the first outer frame edge and a second distance measured perpendicularly between the second inner frame edge and the second outer frame edge is in a range from 3 mm to 12 mm.

7. The glass article of any one of claims 1-6, wherein the first radius of curvature is in a range from 400 mm to 3000 mm.

8. The glass article of any one of claims 1-7, wherein the second radius of curvature is greater than 5000 mm.

9. The glass article of any one of claims 1-8, wherein the first major surface and the second major surface define a thickness of the glass substrate, the thickness being 2 mm or less.

10. The glass article of any one of claims 1-9, wherein the frame comprises a third outer frame edge and a fourth outer frame edge, the third outer frame edge being disposed between the first outer frame edge and the second outer frame edge and the fourth outer frame edge being disposed between the first outer frame edge and the second outer frame edge, and wherein the adhesive is disposed between the glass substrate and the frame surface along the third outer frame edge and along the fourth outer frame edge, the adhesive having a uniform thickness.

11. A glass article, comprising: a frame comprising a convex region curved along a first direction to define a convex curvature extending between a first outer frame edge and a second outer frame edge; a glass substrate; and an adhesive disposed between the frame and the glass substrate, the adhesive joining the glass substrate to the frame to hold the glass substrate in an elastically deformed state to conform the glass substrate to the convex curvature; wherein the adhesive increases in volume toward the first outer frame edge and toward the second outer frame edge such that the glass substrate defines flat tip regions proximal to the first outer frame edge and the second outer frame edge.

12. The glass article of claim 11, wherein the flat tip regions of the glass substrate comprise a radius of curvature of at least 5000 mm.

13. The glass article of claim 11 or claim 12, wherein the convex curvature comprises a radius of curvature in a range from 400 mm to 3000 mm.

14. The glass article of any one of claims 11-13, wherein the adhesive comprises a uniform thickness region, a first variable thickness region, and a second variable thickness region, wherein the first variable thickness region extends from the uniform thickness region to the first outer frame edge and the second variable thickness region extends from the uniform thickness region to the second outer frame edge.

15. The glass article of claim 14, wherein the uniform thickness region comprises a first average thickness, wherein the first and the second variable thickness regions each comprise a second average thickness at the first outer frame edge and the second outer frame edge, respectively, and wherein the second average thickness is at least 0.01 mm greater and up to 0.20 mm greater than the first average thickness.

16. The glass article of claim 15, wherein the first average thickness is in a range from 0.3 mm to 1.3 mm.

17. The glass article of any one of claims 11-16, wherein the frame comprises a bezel extending around a perimeter of the frame, wherein along the first outer frame edge and along the second outer frame edge the bezel comprises a width in a range from 3 mm to 12 mm.

18. A method, comprising: forming a glass substrate over a mold at a temperature of 200 °C or less, the mold defining a concave curvature having a first region with a first radius of curvature disposed between second regions each having a second radius of curvature that is greater than the first radius of curvature and the glass substrate comprising a central portion that conforms to the first radius of curvature and edge regions that conform to the second radius of curvature; attaching a frame to the glass substrate using an adhesive, the frame comprising a convex curvature with a third radius of curvature that matches the first radius of curvature, the convex curvature extending from a first outer frame edge to a second outer frame edge; wherein the adhesive maintains the glass substrate in an elastically deformed state against the frame and wherein the adhesive increases in volume towards the edge regions of the glass substrate.

19. The method of claim 18, further comprising positioning the frame relative to the glass substrate using a plurality of spacers.

20. The method of claim 18 or claim 19, wherein the first radius of curvature is in a range from 400 mm to 3000 mm.

21. The method of any one of claims 18-20, wherein the second radius of curvature is 5000 mm or greater.

22. The method of any one of claims 18-21, wherein the adhesive comprises a uniform thickness region, a first variable thickness region, and a second variable thickness region, wherein the first variable thickness region extends from the uniform thickness region to the first outer frame edge and the second variable thickness region extends from the uniform thickness region to the second outer frame edge.

23. The method of claim 22, wherein the uniform thickness region comprises a first average thickness, wherein the first and the second variable thickness regions each comprise a second average thickness at the first outer frame edge and the second outer frame edge, respectively, and wherein the second average thickness is at least 0.01 mm greater and up to 0.20 mm greater than the first average thickness.

24. The method of claim 23, wherein the first average thickness is in a range from0.3 mm to 1.3 mm.

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