Laminate with high energy absorption and improved roof crus performance

Abstract

Disclosed herein are embodiments of a laminate glazing for a vehicle roof. The laminate glazing includes a first glass ply having first and second major surfaces. The second major surface is opposite to the first major surface. The laminate glazing further includes a second glass ply having third and fourth major surfaces. The fourth major surface is opposite to the third major surface. An adhesive layer is disposed between the second and third major surfaces. The first and second major surfaces define a first thickness of the first glass ply that is from 2.1 mm to 5 mm. The third and fourth major surfaces define a second thickness of the second glass ply that is from 0.5 mm to 1.6 mm. The laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four-point bend test.

Description

LAMINATE WITH HIGH ENERGY ABSORPTION AND IMPROVED ROOF CRUSH PERFORMANCECross-reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Application Serial No. 63 / 541,977, filed on October 02, 2023, the content of which is relied upon and incorporated herein by reference in its entirety.BACKGROUND

[0002] The disclosure relates to glass laminate structures, and more particularly to an asymmetric laminate usable as a roof component or sunroof of a vehicle.

[0003] Glass is being used in greater amounts on vehicles. In particular, the size of glazing, such as windshields, sidelights, rear windows, and sunroofs, is increasing, and in some circumstances, body components of the vehicle that are traditionally made of metal are being replaced with glass. While many of these changes are driven by aesthetics, the vehicle must still meet certain requirements for safety. In particular, occupants must be protected from external hazards, such as other vehicles or environmental structures, and from internal hazards, such as glass shards.SUMMARY

[0004] According to an aspect, embodiments of the present disclosure relate to a laminate glazing for a vehicle roof. The laminate glazing includes a first glass ply having a first major surface and a second major surface in which the second major surface is opposite to the first major surface. The laminate glazing further includes a second glass ply having a third major surface and a fourth major surface. The fourth major surface is opposite to the third major surface, and the third major surface faces the second major surface. An adhesive layer is disposed between the second major surface and the third major surface. The first major surface and the second major surface define a first thickness of the first glass ply, and the first thickness is in a range from 2.1 mm to 5 mm. The third major surface and the fourth major surface define a second thickness of the second glass ply, and the second thickness is in a range from 0.5 mm to 1.6 mm. The laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm. The four-point bend test includes two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the second major surface. The two first sideload points have a first span of 18 mm, and the two second side load points having a second span of 36 mm. The first span and the second span are parallel to the width of the laminate glazing, and the first side load points are driven toward the second side load points that are stationary.

[0005] According to another aspect, embodiments of the present disclosure relate to a laminate glazing for a vehicle roof. The laminate glazing includes a first glass ply having a first major surface and a second major surface in which the second major surface is opposite to the first major surface. The first glass ply is fully thermally tempered or ion exchanged strengthened. The laminate glazing also includes a second glass ply having a third major surface and a fourth major surface, and the fourth major surface is opposite to the third major surface. The third major surface faces the second major surface, and the second glass ply is ion exchanged strengthened with a compressive stress of at least 700 MPa. An adhesive layer is disposed between the second major surface and the third major surface. The first major surface and the second major surface define a first thickness of the first glass ply, and the first thickness being in a range from 2.1 mm to 5 mm. The third major surface and the fourth major surface define a second thickness of the second glass ply, and the second thickness is in a range from 0.5 mm to 1.6 mm. The laminate glazing is configured to withstand a load of at least 8000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm. The four-point bend test includes two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the second major surface. The two first side load points have a first span of 18 mm, and the two second side load points having a second span of 36 mm. The first span and the second span are parallel to the width of the laminate glazing, and the first side load points are driven toward the second side load points that are stationary.

[0006] According to still another aspect, embodiments of the present disclosure relate to a method of forming a laminate glazing for a vehicle roof. In the method, a first glass ply is attached to a second glass ply using an adhesive layer. The first glass ply is formed from a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphor-aluminosilicate glass, and the second glass ply is formed from an ion exchange strengthened alkali aluminosilicate glass. The first glass ply has a first major surface and a second major surface, and the second major surface is opposite to the first major surface. The second glass ply has a third major surface and a fourth major surface, and the fourth majorsurface is opposite to the third major surface. The third major surface faces the second major surface. The first major surface and the second major surface define a first thickness of the first glass ply. The third major surface and the fourth major surface define a second thickness of the second glass ply, and the first thickness is at least 1.5 times the second thickness. A total glass thickness of the first thickness and the second thickness is 6.1 mm or less.

[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.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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. In the drawings:

[0010] FIG. 1 is a top view of a vehicle including an asymmetric glass laminate in the roof, according to an exemplary embodiment;

[0011] FIG. 2 is a schematic side view of an asymmetric glass laminate, according to an exemplary embodiment;

[0012] FIG. 3 is a schematic side view of a curved asymmetric glass laminate, according to an exemplary embodiment;

[0013] FIG. 4 is a schematic side view of an asymmetric glass laminate having a functional layer, according to an exemplary embodiment;

[0014] FIG. 5 depicts a plot of load vs. deflection for an asymmetric glass laminate according to an exemplary embodiment and for an existing symmetric glass laminate;

[0015] FIG. 6 depicts an apparatus for performing a four-point bending test on laminate structures;

[0016] FIGS. 7 and 9 depict loading curves for conventional symmetric glass laminates subjected to a four-point bending test; and

[0017] FIGS. 8 and 10-12 depict loading curves for asymmetric glass laminates, according to an exemplary embodiment, subjected to a four-point bending test.DETAILED DESCRIPTION

[0018] Reference will now be made in detail to various embodiments of an asymmetric glass laminate usable for vehicle roof structures, examples of which are illustrated in the accompanying drawings. Embodiments of the disclosure relate to asymmetric laminates including a thicker outer glass ply and a thinner inner glass ply. The thicker outer glass ply can be any of a variety of glass compositions and may be annealed, fully thermally tempered, semitoughened, or ion-exchanged strengthened. The inner glass ply may be ion-exchanged strengthened. When such a laminate is subjected to loading, the asymmetric glass laminate exhibits a dual loading curve, indicating that the laminate is still able to support loading even after the outer glass ply fails. Advantageously, this dual loading characteristic may allow the laminate to survive multiple loading events. Further, when the asymmetric laminate is used as a roof or sunroof of a vehicle, it is believed that the asymmetric laminate as incorporated into the vehicle body will pass relevant safety standards, such as FMVSS Rule No. 216 regarding roof crush performance, or achieve a good rating according to HHS safety ratings. The additional strength provided via the laminates described herein is particularly beneficial for heavier vehicles, such as battery electric vehicles, which tend to have higher weights than similarly-sized internal combustion engine-based vehicles. These and other aspects and advantages of the disclosed asymmetric laminate will be described more fully below. The embodiments discussed herein are presented by way of illustration and not limitation.

[0019] FIG. 1 depicts a partial, schematic, top view of an example embodiment of a vehicle 100. The vehicle 100 includes a body 110 defining an interior and at least one opening 120 in communication with the interior. The vehicle 100 further includes an automotive glazing 130, i.e., window, disposed in the opening 120. According to embodiments of the present disclosure, the automotive glazing 130 is a sunroof 140 of the vehicle 100. In such embodiments, the sunroof 140 is disposed in an opening 120 in a roof 150 of the vehicle 100. According to one or more other embodiments of the present disclosure, the glazing 130 defines the roof 150 (or a portion thereof) of the vehicle 100. According to still one or more other embodiments of the present disclosure, the vehicle 100 includes a windshield 160, and theglazing 130 is a continuous glazing defining the windshield 160 and roof 150 (or a portion thereof) of the vehicle 100. As used herein, the term “vehicle” relates, in particular, to automobiles.

[0020] As shown in FIG. 2, in embodiments, the automotive glazing 130 is a laminate 200 comprised of a first glass ply 202, a second glass ply 204, and at least one adhesive layer 206 disposed between the first glass ply 202 and the second glass ply 204. In the embodiment depicted in FIG. 1, the laminate 200 includes a single adhesive layer 206 that bonds the first glass ply 202 to the second glass ply 204.

[0021] The first glass ply 202 includes a first major surface 208 and a second major surface 210. The second major surface 210 is opposite to the first major surface 208. A first minor surface 212 extends between the first major surface 208 and the second major surface 210 and around a periphery of the first glass ply 202. Further, the first major surface 208 and the second major surface 210 define a first thickness T1 of the first glass ply 202. In one or more embodiments, the first thickness T1 of the first glass ply 202 is in a range from 2.1 mm to 5 mm, in particular 2.1 mm to 3.5 mm. In one or more embodiments, the first major surface 208 faces the exterior of the vehicle.

[0022] In one or more embodiments, the first glass ply 202 is formed from a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphoraluminosilicate glass. In one or more embodiments, any of the foregoing glass compositions may further include alkali metals, in particular for the purpose of ion exchange strengthening. A particularly suitable borosilicate glass that may be used as the first glass ply 202 is a fusion- formed borosilicate glass disclosed in International Publication No. WO2022 / 125422 (filed on December 6, 2021), titled “Glass with Unique Fracture Behavior for Vehicle Windshield,” the entire contents of which are incorporated herein by reference thereto. In one or more embodiments, the first glass ply 202 is annealed, fully thermally tempered, semi -toughened, or ion exchange strengthened. In one or more embodiments, a fully thermally tempered glass has a surface compressive stress in a range of about 70 MPa or greater achieved through heating and cooling techniques known in the art. In one or more embodiments a semi-toughened glass has a surface compressive stress in a range from about 24 MPa to about 70 MPa achieved through heating and cooling techniques known in the art. In one or more embodiments in which the first glass ply 202 is ion exchange strengthened, the first glass ply 202 comprises a central tension of 10 Mpa or less, in particular 7 Mpa or less, and more particularly 5 Mpa or less.

[0023] The second glass ply 204 includes a third major surface 214 and a fourth major surface 216. The fourth major surface 216 is opposite to the third major surface 214. A second minor surface 218 extends between the third major surface 214 and the fourth major surface 216 and around a periphery of the second glass ply 204. Further, the third major surface 214 and the fourth major surface 216 define a second thickness T2 of the second glass ply 204 therebetween. In one or more embodiments, the second thickness T2 of the second glass ply 204 is less than the first thickness T1 of the first glass ply 202. In one or more embodiments, the second thickness T2 of the second glass ply 204 is in a range from 0.5 mm to 1.6 mm, in particular 0.7 mm to 1.1 mm. In one or more embodiments, the fourth major surface 216 faces the interior of the vehicle.

[0024] In one or more embodiments, the second glass ply 204 is formed from a soda lime silicate glass or an alkali -containing aluminosilicate glass (referred to as an alkali aluminosilicate). In one or more embodiments, the second glass ply 204 is chemically strengthened through an ion-exchange process.

[0025] In one or more embodiments, first glass ply 202 and the second glass ply 204 may be ion-exchanged strengthened to include compressive stress that extends from a surface to a depth of compression (DOC). The compressive stress regions of the glass plies 202, 204 are balanced by a central portion exhibiting a tensile stress. At the DOC, the stress crosses from a positive (compressive) stress to a negative (tensile) stress. However, in the subsequent discussion, all stresses are referred to by their absolute value along with whether the stress is compressive or tensile.

[0026] In one or more embodiments, the glass plies 202, 204 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 plies 202, 204 comprise an alkali aluminosilicate glass, ions in the surface layer of the glass plies 202, 204 and the larger ions which replace them 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 plies 202, 204 generate a stress.

[0027] Ion exchange processes are typically carried out by immersing a glass ply in a molten salt bath (or two or more molten salt baths) containing the larger ions to be exchanged with thesmaller ions in the glass ply. 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 ply (including the structure of the article and any crystalline phases present) and the desired DOC and compressive stress (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, NaNOs, LiNOs, NaSO4 and combinations thereof. The temperature of the molten salt bath typically is in a range from about 370°C up to about 480°C, while immersion times range from about 15 minutes up to about 100 hours depending on glass substrate thickness, bath temperature, and glass (or monovalent ion) diffusivity. However, temperatures and immersion times different from those described above may also be used.

[0028] In one or more embodiments, the glass plies 202, 204 may be immersed in a molten salt bath of 100% NaNCh, 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 ply may be immersed in a molten mixed salt bath including from about 5% to about 90% KNO3 and from about 10% to about 95% NaNCh. In one or more embodiments, the glass ply 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.

[0029] In one or more embodiments, the glass ply 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.

[0030] 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 plies described herein.

[0031] In one or more embodiments, where more than one monovalent ion is exchanged into the glass ply, the different monovalent ions may exchange to different depths within the glass ply (and generate different magnitudes of stresses within the glass ply at different depths). The resulting relative depths of the stress-generating ions can be determined and cause different characteristics of the stress profile.

[0032] 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,” the contents 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 ply. In other embodiments, the maximum compressive stress may occur at a depth below the surface, giving the compressive profile the appearance of a “buried peak.”

[0033] 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 a glass ply is chemically strengthened by an ion exchange treatment, FSM or SCALP may be used depending on which ion is exchanged into the glass ply. Where the stress in the glass ply is generated by exchanging potassium ions into the glass ply, FSM is used to measure DOC. Where the stress is generated by exchanging sodium ions into the glass ply, SCALP is used to measure DOC. Where the stress in the glass ply 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 plies is measured by FSM. Central tension (CT) is the maximum tensile stress and is measured by SCALP.

[0034] In one or more embodiments, the glass ply may be strengthened to exhibit a DOC that is described as a fraction of the thickness Tl, T2 of the glass plies 202, 204 (as describedherein). For example, in one or more embodiments, the DOC may be in the range of about 0.05*(Tl, T2) to about O.25*(T1, T2). 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 plies 202, 204 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, 700 MPa or greater, or about 1050 MPa or greater. In one or more embodiments, the second glass ply 204 is, in particular, strengthened to have a CS of 700 MPa or greater.

[0035] In one or more embodiments, the second glass ply 204 may have a maximum tensile stress or central tension (CT) in the range of about 20 MPa to about 100 MPa.

[0036] In one or more embodiments, the first glass ply 202 (if ion-exchange strengthened) has a maximum tensile stress or CT of 10 MPa or less, in particular 7 MPa or less, and most particularly 5 MPa or less. In order to achieve a first glass ply 202 of ion-exchanged strengthened alkali aluminosilicate glass, it was determined that a CS in the range of about 300 MPa to about 900 MPa with a DOC of about 20 pm to 40 pm produced a CT in a range of about 4 MPa to about 10 MPa. Providing a CT in such a range beneficially contributed to the crash test performance of the laminates described herein by providing durability of the first glass ply 202. CTs greater than this range can lead to flaw propagation in the first glass ply 202 and inferior strength.

[0037] The at least one adhesive layer 206 is disposed between the second major surface 210 of the first glass ply 202 and the third major surface 214 of the second glass ply 204. In one or more embodiments, the adhesive layer 206 is bonded to the second major surface 210 and to the third major surface 214. In one or more embodiments, the at least one adhesive layer 206 has a thickness is in a range from 0.36 mm to 1.6 mm, in particular 0.36 mm to 0.8 mm, between the first glass ply 202 and the second glass ply 204. In one or more embodiments, the at least one adhesive layer 206 is formed from a polyvinyl butyral (PVB), an acoustic PVB (APVB), an ethylene-vinyl acetate (EVA), a thermoplastic polyurethane (TPU), an ionomer, a polyester (PES), or a polyethylene terephthalate (PET). In one or more embodiments, the at least one adhesive layer 206 includes one or more functional additives, such as solar-absorbing pigment, a tinting colorant, UV absorbing compounds, or light scattering particles.

[0038] In one or more embodiments, the first glass ply 202 or second glass play 204 may be provided with a functional or decorative coating in addition to or in the alternative to the functional or decorative element of the adhesive layer 206. In embodiments, the coating is at least one of an infrared reflective (IRR) coating, frit, anti -reflective coating, or pigment coating.In an example embodiment of an IRR, the second major surface 210 of the first glass ply 202 or the third major surface 214 of the second glass ply 204 is coated with an infrared-reflective film and, optionally, one or more layers of a transparent dielectric film. In embodiments, the infrared-reflecting film comprises a conductive metal, such as silver, gold, or copper, that reduces the transmission of heat through the coated ply 202, 204. In embodiments, the optional dielectric film can be used to anti-reflect the infrared-reflecting film and to control other properties and characteristics of the coating, such as color and durability. In embodiments, the dielectric film comprises one or more oxides of zinc, tin, indium, bismuth, and titanium, among others. In an example embodiment, the IRR coating includes one or two silver layers each sandwiched between two layers of a transparent dielectric film. In embodiments, the IRR coating is applied using, e.g., physical or chemical vapor deposition or via lamination.

[0039] In embodiments, the coating is an anti-reflective coating. In particular embodiments, the anti -reflective coating is applied to the first major surface 208 of the first glass ply 202 or to the fourth major surface 216 of the second glass ply 204. In embodiments, the anti -reflective coating comprises multiple layers of low and high index materials or low, medium, and high index materials. For example, in embodiments, the anti -reflective coating includes from two to twelve layers of alternating low and high index materials, such as silica (low index) and niobia (high index). In another example embodiment, the anti-reflective coating includes from three to twelve layers of repeating low, medium, and high index materials, such as silica (low index), alumina (medium index), and niboia (high index). In still other embodiments, the low index material in the stack may be an ultra low index material, such as magnesium fluoride or porous silica. In general, anti-reflective coatings having more layers in the stack will perform better at higher angles of incidence than anti -reflective coatings having less layers in the stack. For example, at an angle of incidence of, e.g., greater than 60°, an anti -reflective coating stack having four layers will perform better (less reflection) than an anti -reflective coating stack having two layers. Further, in embodiments, an anti -reflective coating stack having an ultra low index material will perform better (less reflection) than an anti -reflective coating stack having a low index material. Other anti -reflective coatings known in the art may also be suitable for application to the laminate 200.

[0040] In the embodiment shown in FIG. 2, the laminate 200 consists of the first glass ply 202, the second glass ply 204, and one adhesive layer 206. In the formed laminate 200, the second major surface 210 of the first glass ply 202 is bonded to adhesive layer 206, and the third major surface 214 of the second glass ply 204 is bonded to the adhesive layer 206. In particular, during assembly of the laminate 200, sufficient heat and pressure is applied to the stack of firstglass ply 202, adhesive layer 206, and second glass ply 204 to drive out substantially all of the air between the layers of the first glass ply 202, adhesive layer 206, and second glass ply 204 such that the adhesive layer 206 bonds the first glass ply 202 to the second glass ply 204.

[0041] In one or more embodiments, the laminate 200 comprises at least one curvature 220 as shown in FIG. 3. For example, the laminate 200 may comprise a curvature extending across at least a portion of the length and / or width of the first major surface 208 of the first glass ply 202 and / or the fourth major surface 216 of the second glass ply 204. In one or more embodiments, the first glass ply 202 and / or the second glass ply 204 is hot-formed at or above the softening temperature of the glass composition to create the curvature. In one or more embodiments, the first glass ply 202 and / or the second glass ply 204 is cold-formed at a temperature below the softening temperature of the glass composition, in particular at a temperature of 200 °C or less, 175 °C or less, 150 °C or less, 125 °C or less, 100 °C or less, or at room temperature, to create the curvature. In one or more embodiments, the second glass ply 204 may include a curvature 220 having a radius of curvature R in a range from 40 mm to 10,000 mm or greater (i.e., flat or no curvature), in particular from 300 mm to 2000 mm. In one or more embodiments, the second glass ply 204 may have a cross curvature that intersects the first curvature 220, and in one or more embodiments, the cross curvature may have a radius of curvature in a range from 500 mm to 10,000 mm or greater (i.e., flat or no curvature), in particular from 1000 mm to 5000 mm. In one or more embodiments, the one or more curvatures define a Gaussian curvature in a range from 0 mm'2(inverse mm2) to 357 x 10'7mm'2, in particular in a range from 1 x 10'7mm'2to 3 x 10'7mm'2. As shown in FIG. 3, the first glass ply 202 may be pressed against the second glass ply 204 so that the first glass ply 202 conforms to the curvature 224 of the second glass ply 204. In one or more embodiments, the second major surface 208 faces the exterior of the vehicle.

[0042] In the embodiments depicted in FIGS. 2 and 3, the laminate 200 included just the three layers of the first glass ply 202, the second glass ply 204, and the adhesive layer 206. However, in one or more other embodiments, the laminate 200 may include additional layers. For example, as shown in FIG. 4, the laminate 200 further includes a functional layer 304. In one or more such embodiments, a first adhesive layer 206 is disposed between the functional layer 304 and the first glass ply 202. In one or more embodiments, the functional layer 304 comprises an infrared reflective layer. In one or more embodiments, the functional layer 304 comprises a display module, such as an organic light emitting diode (OLED) display, an e-ink display, or a dispersed liquid crystal display. In one or more embodiments, the functional layer304 is a layer in which transmission of light in the visible spectrum through the first glass ply 202 can be varied by application of an electric voltage, such as dispersed liquid crystals, suspended particle devices, or electrochromic films. In one or more embodiments, the laminate 200 further includes a second adhesive layer 306 such that the functional layer 304 is disposed between the first adhesive layer 206 and the second adhesive layer 306.

[0043] The laminate 200 used for the glazing 130 of the vehicle 100 is particularly suitable for use on the roof 150 of a vehicle 100, i.e., as a component of the roof 150, such as a sunroof 140, or as the roof 150 itself. FMVSS Rule No. 216 (2009) establishes regulations for roof crush performance for vehicles. For vehicles weighing less than 6000 lbs., the roof 150 should withstand at least three times the unloaded weight of the vehicle 100. For vehicles weighing 6000 to 10,000 lbs., the roof 150 should withstand at least 1.5 times the unloaded weight of the vehicle 100. The requirements must be satisfied for both the driver and passenger sides of the vehicle 100. Further, vehicles 100 having roofs 150 with glass elements should be able to withstand 80,000 Newtons (N).

[0044] During testing under FMVSS Rule No. 216 (2009), force is applied to the front corner of each of the driver side and passenger side of the roof in a downward direction perpendicular to the lower surface of the test device at a rate of not more than 13 mm per second until reaching a force (N) of 1.5 times the unloaded vehicle weight of the test vehicle, measured in kilograms and multiplied by 9.8, and the displacement of the test device is measured. The test device is not moved more than 127 mm when determining whether the vehicle can withstand the force of 1.5 times its unloaded weight. According to IIHS safety ratings, a vehicle that is able to withstand a force of at least 4 times the vehicle’s unloaded weight achieves a “good” rating. According to embodiments of the present disclosure, vehicles 100 incorporating roofs 150 or roof elements (such as a sunroof 140) incorporating the disclosed laminate 200, having highly asymmetric glass plies 202, 204, are able to meet or exceed the requirements of FMVSS Rule No. 216 (2009).

[0045] As vehicles transition from internal combustion engines to battery electric vehicles, the weight of the vehicle is expected to increase because of the weight of the battery cells in the vehicle. As discussed in the previous paragraph, the acceptable performance of the vehicle in a roof crush test under FMVSS Rule No. 216 (2009) is based on the ability of the vehicle to withstand a multiple of its unloaded weight, and thus, heavier vehicles will require more robust materials for construction. In addition, modem vehicle designs have sought to incorporate more and more aesthetic elements, such as glass, into the vehicle design. Specifically, roofs150 are incorporating larger sunroofs 140, and in some instances, entire roofs 150 are being made from glass. Accordingly, performance of new vehicles, especially new battery electric vehicles, in roof crush testing will increasingly depend on the strength of the glass elements in the roof 150. Applicant believes that the loading characteristics of the presently disclosed asymmetric glass laminates will facilitate achievement of a “good” rating according to IIHS for a vehicle incorporating a roof or roof component of the presently disclosed asymmetric glass laminate when tested in accordance with FMVSS Rule No. 216 (2009).

[0046] The disclosed asymmetric laminates 200 have a first (outer) glass ply 202 that is thicker than a second (inner) glass ply 204. As discussed above, the first glass ply 202 has a thickness in a range from 2.1 mm to 5 mm, and the second glass ply 204 has a thickness in a range from 0.5 mm to 1.6 mm. In one or more embodiments, the first thickness (Tl) of the first glass ply 202 is at least 1.5 times, at least 2 times, at least 2.5 times, at least 3 times, at least 3.5 times, or at least 4 times the second thickness (T2) of the second glass ply 204. In one or more embodiments, the first thickness (Tl) of the first glass ply 202 is up to 10 times, in particular up to 5 times, the second thickness (T2) of the second glass ply 204. In one or more embodiments, the laminate 200 has a total glass thickness (i.e., combined thickness of the first glass ply 202 and the second glass ply 204) of 6.1 mm or less, in particular 5.0 mm or less. In one or more embodiments, the laminate 200 has a total glass thickness of 2.6 mm or more, in particular 3.0 mm or more.

[0047] The asymmetric laminates 200 demonstrate significantly higher stiffness under loading (i.e., lower deflection) as well as increased load to failure of the first (outer) glass ply 202 than certain existing symmetric laminates. This improved performance is particularly seen for laminates where the first thickness Tl of the first glass ply 202 is at least 2.5 times the second thickness T2 of the second glass ply 204. In one or more embodiments, the laminate 200 is configured to withstand a load of at least 2000 N, at least 3000 N, or at least 4000 N as measured using a four point bend test as described below. In one or more particular embodiments, the laminate 200 is configured to withstand a load of at least 8000 N, at least 9000 N, or at least 10,000 N as measured using the four point bend test. Additionally, after failure of the first glass ply 202, the second (inner) glass ply 204 is able to withstand additional loading prior to its failure and, thus, the complete failure of the laminate 200. These concepts are illustrated in a graph of FIG. 5.

[0048] In particular, FIG. 5 is a graph of deflection vs. loading as measured using a four-point test according to ASTM D6272 for an existing symmetric laminate and for an asymmetric laminate 200 according to the present disclosure. For the symmetric glass laminate, each glassply was annealed soda lime glass having a thickness of 2.1 mm. For the asymmetric laminate 200, the first (outer) glass ply 202 was fully tempered soda lime glass having a thickness of 3.2 mm, and the second (inner) glass ply 204 was an ion-exchanged alkali aluminosilicate glass (Gorilla® glass available from Corning Incorporated, Coming, NY) having a thickness of 1.1 mm. Thus, both laminates had a total glass thickness of 4.2 mm. Further, both laminates included a PVB adhesive layer having a thickness of 0.8 mm.

[0049] In FIG. 5, it can be seen that the slope of the loading curve is steeper, resulting in less deflection, for the disclosed asymmetric laminate 200 as compared to the existing symmetric laminate despite having the same total glass thickness. Further, the symmetric laminate fails at a lower loading (426 Ibf), whereas the disclosed asymmetric laminate 200 is able to withstand up to 1150 Ibf before failure. Further, the second, inner glass ply of the symmetric laminate breaks essentially at the same loading as the first, outer glass ply, whereas the second (inner) glass ply 204 of the asymmetric laminate 200 remains intact after breakage of the first glass ply 202. As shown in FIG. 5, despite failure of the first (outer) glass ply 202, the second (inner) glass ply 204 is able to continue supporting additional loading (about another 900 Ibf). Thus, the asymmetric laminate 200 is able to withstand about 3 times greater loading before initial fracture and 5 times more total loading to failure for both plies 202, 204 than the existing symmetric laminate.

[0050] Table 1, below, provides additional comparative examples of symmetric laminates and examples of the disclosed asymmetric laminates. Each of the laminates was loaded on the outer glass ply via four-point bending test until failure.

[0051] FIG. 6 depicts a glass laminate 200 undergoing a four-point bending test according to ASTM D6272 using a testing apparatus 400. As shown, the apparatus 400 comprises two first side load points 410 and two second side load points 420, which are bars that extend across and contact the first major surface 208 of the first glass ply 202 and the fourth major surface 216 of the second glass ply 204, respectively. The two first side load points 410 and the two second side load points 420 have blunt, radiused ends such that they can generate stress in the glass laminate 200 without forming surface flaws in the location they contact. Unless otherwise noted, the ends of the first side load points 410 and two second side load points 420 comprise a 5 mm radius. The first side load points 410 are shown in contact with the first major surface 208 and the second side load points 420 are shown in contact with the fourth major surface 216. The first side load points 410 are laterally spaced nearer to one another than the second side load points 420. In operation, the first side load points 410 translate in a first direction 430 to apply a force to the first major surface 208, which causes the second side load points420 (which do not translate) to also apply force is a second direction 440, opposite the first direction 430. Unless otherwise noted herein, the first side load point 410 translates in the first direction at a velocity of 5 mm / minute to apply a force to the glass laminate 200.

[0052] While not intending to be limited by the theory, the apparatus 400 places a large region of the glass laminate 200 under approximately uniform stress. In operation, the applied force is increased and measured as a function of time until glass laminate 200 breaks. The maximum applied force corresponds to the force that causes the glass laminate 200 to break. As reported below, the breakage of the glass laminate 200 is provided in terms of load to breakage of the first glass ply 202, load to breakage of the second glass ply 204, and total load to breakage of the glass laminate 200. Using the dimensions of the glass laminate 200 and the maximum applied load, the stress at breakage can be calculated. The following formula may be used to calculate the stress at failure, in units of megaPascals (MPa):3 X L1 x FStress (MPa) = - - -4 x t2x L2

[0053] Where LI is the support span distance (mm), which is the distance between the two second side load points 420, F is the applied load (N), L2 is the length of the glass laminate 200 (mm), and t is the total glass thickness (T1 + T2).

[0054] In measurements taken herein, L2 is 100 mm, LI is 36 mm, and t is provided in Table 1, below. The above assumes the span under load, which is the distance between the two first side load points 410, is half the distance of the support span distance LI holding the glass laminate 200 (i.e., 18 mm in this case). An individual glass laminate 200 may have a break resistance that is higher or lower, but on average such 4-point bend measurements characterize a distribution of parts. Such a distribution mean and its standard deviation can be reasonably characterized by breaking 5 glass laminates 200 fabricated in a batch, with more statistics being beneficial. For the comparative examples and examples according to the present disclosure discussed below, the laminates were tested in samples having a length (L2) of 100 mm and a width (measured perpendicular to length L2) of 50 mm. The first side load points 410 and the second side load points 420 each had bar lengths longer than the width of samples such that, along the line of loading, the entire width of the samples were in contact with the first and second side load points 410, 420.Table 1. Laminate ply thicknesses and loading characteristics

[0055] Comparative Example 1 (CE1) included two plies of annealed soda lime glass. As can be seen, the symmetric laminate was able to withstand an initial load of 1649 N before failure of the outer ply and another 1116 N before failure of the inner ply. Thus, for a total glass thickness of 4.2 mm, CE1 is able to withstand a total load of 2765 N. Comparative Example 2 (CE2) is slightly asymmetric with a difference of 0.5 mm in thickness between the outer glass ply and the inner glass ply. Both glass plies were annealed soda lime glass. The outer glass ply failed at a load of 1376 N, and the inner glass ply failed at a load of 543 N for a total load of 1919 N. From CE2, it can be seen that slight asymmetry does not provide enhanced performance of the laminate.

[0056] Example 1 (El) includes a larger difference (1 mm) in thickness between the outer glass ply and the inner glass ply. The outer glass ply was annealed soda lime glass, and the inner glass ply was ion-exchanged alkali aluminosilicate glass (Gorilla® glass). Despite the decrease in total glass thickness to 3.2 mm and despite having the same outer ply thickness as CE1 and CE2, the highly asymmetric laminate was able to withstand a total load of up to 3041 N.

[0057] Example 2 (E2) also included an outer glass ply of soda lime glass having a thickness of 2.1 mm and an inner glass ply of ion-exchanged alkali aluminosilicate glass. In E2, the asymmetry was further increased to a difference in thickness of 1.4 mm. As can be seen in Table 1, the total load to failure was less than for El, but the total glass thickness was less than El. Notwithstanding, the asymmetric laminate was still able to withstand a load of more than 2000 N.

[0058] Example 3 (E3) was similar to Example 1 in that the outer glass ply was soda lime glass having a thickness of 2.1 mm and the inner glass ply was alkali aluminosilicate glass having a thickness of 1.1 mm. However, the outer glass ply was not annealed in E3, and the alkali aluminosilicate glass had a higher compressive stress. As can be seen from Table 1, the inner glass ply is able to withstand a high load to failure, up to 3233 N, and the total load to failure was 3815 N.

[0059] Example 4 (E4) was an asymmetric laminate having an increased total glass thickness of 3.4 mm comprised of a 2.7 mm outer glass ply and a 0.7 mm inner glass ply. The outer glass ply was soda lime glass (annealed), and the inner glass ply was alkali aluminosilicate glass (the same as El and E2). As can be seen, by slightly increasing the total glass thickness, the total load to failure is increased to 4081 N.

[0060] Example 5 (E5) further increased the total glass thickness to 3.9 mm, including an outer glass ply having a thickness of 3.2 mm and an inner glass ply having a thickness of 0.7 mm. The outer glass ply was soda lime glass, and the inner glass ply was alkali aluminosilicate glass (the same was El, E2, and E4). Again, increasing the total glass thickness increased the total load to failure up to 4492 N.

[0061] Example 6 (E6) further increased the total glass thickness to 4.3 mm, including an outer glass ply having a thickness of 3.2 mm and an inner glass ply having a thickness of 1.1 mm. The outer glass ply was fully thermally tempered soda lime glass, and the inner glass ply was alkali aluminosilicate glass (the same as E3). As can be seen from Table 1, the load to failure for both the outer ply and the inner ply was significantly increased to 5418 N and 4538 N, respectively. The total load to failure was 9956 N.

[0062] Example 7 (E7) decreased the total glass thickness to 3.6 mm, but both glass plies were ion-exchange strengthened alkali aluminosilicate glass (both the same glass as E3 and E6). The outer glass ply had a thickness of 2.85 mm, and the inner glass ply had a thickness of 0.7 mm. The outer glass ply had a CS of 785 MPa and a DOL of 33 pm, and the inner glass ply had a CS of 844 MPa and a DOL of 42 pm. The outer glass ply was able to withstand a load of 10,020 N, and the inner glass ply was able to withstand a load of 3233 N. The total load to failure was 13,254 N.

[0063] Thus, Table 1 demonstrates that the highly asymmetric glass laminates withstood higher loads than the symmetric or minorly asymmetric glass laminates. Further, the characteristics of the glass plies could be manipulated to achieve desired results. For example, the thicknesses of the plies can be manipulated to provide sufficient strength, e.g., to pass FMVSS Rule No. 216 while also optimizing for light-weighting of the vehicle. Further, thecomposition and temper of the glass plies could be manipulated to increase the load to failure as needed for a particular application.

[0064] FIGS. 7 and 8 depict graphs of load and deflection for a symmetric glass laminate (2.1 mm plies of soda lime glass) and for an asymmetric glass laminate (3.1 mm outer glass ply of soda lime glass and 1.1 mm inner glass ply of ion-exchange strengthened alkali aluminosilicate glass), respectively. Both laminates were loaded to approximately 400 Ibf. As can be seen in a comparison of FIGS. 7 and 8, the symmetric glass laminate exhibited greater deflection (0.805 mm) than the asymmetric glass laminate (0.619 mm). Thus, the asymmetric glass laminate according to the present disclosure is stiffer than the symmetric glass laminate.

[0065] FIGS. 9 and 10 depict graphs of load and deflection for the same symmetric glass laminate and for the same asymmetric glass laminate of FIGS. 7 and 8. The symmetric laminate failed when undergoing the loading shown in FIG. 9. As can be seen in FIG. 9, the symmetric laminate is able to withstand a load of 426.86 Ibf before failing, and the laminate deflected 0.832 mm at that level of loading. Neither of the glass plies failed when the represented laminate underwent the loading shown in FIG. 10. From FIG. 10, it can be seen that the asymmetric laminate has been loaded to 757 Ibf without either ply failing, and even at that much higher loading level, the deflection is only 0.902 mm. FIG. 11 depicts the asymmetric laminate represented in FIG. 10 loaded until failure of the outer glass ply, which was at a load of 1152.36 Ibf. At failure of the outer glass ply, the deflection was 1.184 mm. Despite the cracking of the outer glass ply, the inner glass ply remained intact. In particular, as shown in FIG. 12, the asymmetric glass laminate is able to contain support additional loading. In FIG. 12, the inner laminate continues to support 771.57 Ibf and deflects up to 2.250 mm.

[0066] Thus, as shown in FIG. 12, the asymmetric laminate according to the present disclosure exhibits dual loading curves: an initial, steeper loading curve reflective of the stiffness of both intact plies of the asymmetric laminate and a later, flatter loading curve reflective of the intact inner ply after failure of the outer ply. Advantageously, and in contrast to the existing symmetric laminates where both plies fail at the same time, the asymmetric laminate according to the present disclosure is able to withstand multiple loadings, such as potentially a vehicle roof experiencing multiple rollovers or other loading events.

[0067] Further, the fourth major surface of the glass laminate was subjected to headform laceration testing in which a headform having a weight of 4.8 kg covered with two chamois skins (each chamois being 0.8 mm thick) was directed at the inner glass ply at an impact velocity of 13.4 m / s and an incident angle of 45°. When the headform impacted existing soda lime silicate plies, the chamois skins exhibited multiple significant tears. By contrast, thechamois skins contacting the inner glass ply of alkali aluminosilicate glass exhibited no significant tears. Accordingly, it is believed that the asymmetric glass laminates according to the present disclosure will reduce the possibility of lacerations after impact.

[0068] Embodiments of the present disclosure may be further understood in view of the following aspects.

[0069] An aspect (1) of the present disclosure pertains to a laminate glazing for a vehicle roof, comprising: a first glass ply having a first major surface and a second major surface, the second major surface being opposite to the first major surface; a second glass ply having a third major surface and a fourth major surface, the fourth major surface being opposite to the third major surface, the third major surface facing the second major surface; an adhesive layer disposed between the second major surface and the third major surface; wherein the first major surface and the second major surface define a first thickness of the first glass ply, the first thickness being in a range from 2.1 mm to 5 mm; wherein the third major surface and the fourth major surface define a second thickness of the second glass ply, the second thickness being in a range from 0.5 mm to 1.6 mm; and wherein the laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

[0070] An aspect (2) of the present disclosure pertains to a laminate glazing according to the aspect (1), wherein the first glass ply comprises a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphor-aluminosilicate glass.

[0071] An aspect (3) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(2), wherein the first glass ply is annealed.

[0072] An aspect (4) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(2), wherein the first glass ply is fully thermally tempered.

[0073] An aspect (5) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(2), wherein the first glass ply is semi -toughened.

[0074] An aspect (6) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(2), wherein the first glass ply is ion-exchange strengthened.

[0075] An aspect (7) of the present disclosure pertains to a laminate glazing according to the aspect (6), wherein the first glass ply comprises a maximum central tension of 10 MPa or less.

[0076] An aspect (8) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(7), wherein the second glass ply is a soda lime silicate glass or an alkali aluminosilicate glass.

[0077] An aspect (9) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(8), wherein the second glass ply is ion-exchange strengthened.

[0078] An aspect (10) of the present disclosure pertains to a laminate glazing according to the aspect (9), wherein the second glass ply comprises a compressive stress of at least 700 MPa.

[0079] An aspect (11) of the present disclosure pertains to a laminate glazing according to any of the aspects (9)-(10), wherein the first glass ply is fully thermally tempered or ion exchange strengthened.

[0080] An aspect (12) of the present disclosure pertains to a laminate glazing according to the aspect (11), wherein the laminate glazing is configured to withstand a load of at least 8000 N as measured using the four point bend test.

[0081] An aspect (13) of the present disclosure pertains to a laminate glazing according to any of the aspects (1)-(12), wherein the first thickness is at least 1.5 times the second thickness.

[0082] An aspect (14) of the present disclosure pertains to a laminate glazing according to any of the aspects (l)-(l 3), wherein the first thickness is up to 10 times the second thickness.

[0083] An aspect (15) of the present disclosure pertains to a laminate glazing according to any of the aspects ( 1 )-( 14), wherein a total thickness of the first thickness and the second thickness is 5.0 mm or less.

[0084] An aspect (16) of the present disclosure pertains to a laminate glazing for a vehicle roof, comprising: a first glass ply having a first major surface and a second major surface, the second major surface being opposite to the first major surface, the first glass ply being fully thermally tempered or ion exchanged strengthened; a second glass ply having a third major surface and a fourth major surface, the fourth major surface being opposite to the third major surface, the third major surface facing the second major surface, the second glass ply being ion exchanged strengthened with a compressive stress of at least 700 MPa; an adhesive layer disposed between the second major surface and the third major surface; wherein the first major surface and the second major surface define a first thickness of the first glass ply, the first thickness being in a range from 2.1 mm to 5 mm; wherein the third major surface and the fourth major surfacedefine a second thickness of the second glass ply, the second thickness being in a range from 0.5 mm to 1.6 mm; and wherein the laminate glazing is configured to withstand a load of at least 8000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four- point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

[0085] An aspect (17) of the present disclosure pertains to a laminate glazing according to the aspect (16), wherein the first glass ply is fully thermally tempered.

[0086] An aspect (18) of the present disclosure pertains to a laminate glazing according to the aspect (17), wherein the first glass ply is ion exchanged strengthened.

[0087] An aspect (19) of the present disclosure pertains to a laminate glazing according to the aspect (18), wherein the first glass ply comprises a maximum central tension of 10 MPa or less.

[0088] An aspect (20) of the present disclosure pertains to a laminate glazing according to any of the aspects (16)-(19), wherein the first glass ply comprises a soda lime silicate glass or aluminosilicate glass.

[0089] An aspect (21) of the present disclosure pertains to a laminate glazing according to any of the aspects (16)-(20), wherein the second glass ply comprises a soda lime silicate glass or an aluminosilicate glass.

[0090] An aspect (22) of the present disclosure pertains to a vehicle comprising: a vehicle body defining an interior and an exterior of the vehicle, the vehicle body comprising a roof having an opening; the laminate glazing according to any one of the aspects (1)-(15) or (16)-(21) disposed within the opening; wherein the first major surface is disposed on the exterior of the vehicle and the fourth major surface is disposed on the interior of the vehicle.

[0091] An aspect (23) of the present disclosure pertains to a vehicle according to the aspect (22), wherein the vehicle comprises an unloaded weight and wherein the roof is configured to withstand at least 1.5 times the unloaded weight of the vehicle as measured according to FMVSS Rule No. 216.

[0092] An aspect (24) of the present disclosure pertains to a vehicle according to any of the aspects (22)-(23), wherein the roof is configured withstand a force of 80,000 N as measured according to FMVSS Rule No. 216.

[0093] An aspect (25) of the present disclosure pertains to a method of forming a laminate glazing for a vehicle roof, the method comprising: attaching a first glass ply to a second glass ply using an adhesive layer, the first glass ply comprising a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphoraluminosilicate glass and the second glass ply comprising an ion exchange strengthened alkali aluminosilicate glass; wherein the first glass ply comprises a first major surface and a second major surface, the second major surface being opposite to the first major surface; wherein the second glass ply comprises a third major surface and a fourth major surface, the fourth major surface being opposite to the third major surface, the third major surface facing the second major surface; wherein the first major surface and the second major surface define a first thickness of the first glass ply; wherein the third major surface and the fourth major surface define a second thickness of the second glass ply, the first thickness being at least 1.5 times the second thickness; and wherein a total glass thickness of the first thickness and the second thickness is 6.1 mm or less.

[0094] An aspect (26) of the present disclosure pertains to a method according to the aspect (25), wherein the laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

[0095] An aspect (27) of the present disclosure pertains to a method according to any of the aspects (25)-(26), wherein the first glass ply is annealed.

[0096] An aspect (28) of the present disclosure pertains to a method according to any of the aspects (25)-(26), wherein the first glass ply is fully thermally tempered.

[0097] An aspect (29) of the present disclosure pertains to a method according to any of the aspects (25)-(26), wherein the first glass ply is semi-toughened.

[0098] An aspect (30) of the present disclosure pertains to a method according to any of the aspects (25)-(26), wherein the first glass ply is ion-exchange strengthened.

[0099] An aspect (31) of the present disclosure pertains to a method according to the aspect (30), wherein the first glass ply comprises a maximum central tension of 10 MPa or less.

[0100] An aspect (32) of the present disclosure pertains to a method according to any of the aspects (25)-(31), wherein the second glass ply is ion-exchange strengthened.

[0101] An aspect (33) of the present disclosure pertains to a method according to the aspect (32), wherein the second glass ply comprises a compressive stress of at least 700 MPa.

[0102] An aspect (34) of the present disclosure pertains to a method according to any of the aspects (32)-(33), wherein the first glass ply is fully thermally tempered or ion exchange strengthened.

[0103] An aspect (35) of the present disclosure pertains to a method according to the aspect (35), wherein the laminate glazing is configured to withstand a load of at least 8000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

[0104] 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.

[0105] 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 theart, 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 laminate glazing for a vehicle roof, comprising: a first glass ply having a first major surface and a second major surface, the second major surface being opposite to the first major surface; a second glass ply having a third major surface and a fourth major surface, the fourth major surface being opposite to the third major surface, the third major surface facing the second major surface; an adhesive layer disposed between the second major surface and the third major surface; wherein the first major surface and the second major surface define a first thickness of the first glass ply, the first thickness being in a range from 2.1 mm to 5 mm; wherein the third major surface and the fourth major surface define a second thickness of the second glass ply, the second thickness being in a range from 0.5 mm to 1.6 mm; and wherein the laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four-point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

2. The laminate glazing of claim 1, wherein the first glass ply comprises a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphor-aluminosilicate glass.

3. The laminate glazing of claim 1 or claim 2, wherein the first glass ply is annealed.

4. The laminate glazing of claim 1 or claim 2, wherein the first glass ply is fully thermally tempered.

5. The laminate glazing of claim 1 or claim 2, wherein the first glass ply is semitoughened.

6. The laminate glazing of claim 1 or claim 2, wherein the first glass ply is ion-exchange strengthened.

7. The laminate glazing of claim 6, wherein the first glass ply comprises a maximum central tension of 10 MPa or less.

8. The laminate glazing of any one of claims 1-7, wherein the second glass ply is a soda lime silicate glass or an alkali aluminosilicate glass.

9. The laminate glazing of any one of claims 1-8, wherein the second glass ply is ionexchange strengthened.

10. The laminate glazing of claim 9, wherein the second glass ply comprises a compressive stress of at least 700 MPa.

11. The laminate glazing of claim 9 or claim 10, wherein the first glass ply is fully thermally tempered or ion exchange strengthened.

12. The laminate glazing of claim 11, wherein the laminate glazing is configured to withstand a load of at least 8000 N as measured using the four point bend test.

13. The laminate glazing of any one of claims 1-12, wherein the first thickness is at least 1.5 times the second thickness.

14. The laminate glazing of any one of claims 1-13, wherein the first thickness is up to 10 times the second thickness.

15. The laminate glazing of any one of claims 1-14, wherein a total thickness of the first thickness and the second thickness is 5.0 mm or less.

16. A vehicle comprising: a vehicle body defining an interior and an exterior of the vehicle, the vehicle body comprising a roof having an opening; and the laminate glazing according to any one of claims 1-15 disposed within the opening; wherein the first major surface is disposed on the exterior of the vehicle and the fourth major surface is disposed on the interior of the vehicle.

17. The vehicle of claim 16, wherein the vehicle comprises an unloaded weight and wherein the roof is configured to withstand at least 1.5 times the unloaded weight of the vehicle as measured according to FMVSS Rule No. 216.

18. The vehicle of claim 16 or claim 17, wherein the roof is configured withstand a force of 80,000 N as measured according to FMVSS Rule No. 216.

19. A method of forming a laminate glazing for a vehicle roof, the method comprising: attaching a first glass ply to a second glass ply using an adhesive layer, the first glass ply comprising a soda lime silicate glass, a borosilicate glass, an aluminosilicate glass, a boroaluminosilicate glass, or a phosphor-aluminosilicate glass and the second glass ply comprising an ion exchange strengthened alkali aluminosilicate glass; wherein the first glass ply comprises a first major surface and a second major surface, the second major surface being opposite to the first major surface; wherein the second glass ply comprises a third major surface and a fourth major surface, the fourth major surface being opposite to the third major surface, the third major surface facing the second major surface; wherein the first major surface and the second major surface define a first thickness of the first glass ply; wherein the third major surface and the fourth major surface define a second thickness of the second glass ply, the first thickness being at least 1.5 times the second thickness; and wherein a total glass thickness of the first thickness and the second thickness is 6.1 mm or less.

20. The method of claim 19, wherein the laminate glazing is configured to withstand a load of at least 2000 N on the first major surface without failing as measured using a four- point bend test on a sample of the laminate glazing having a width of 50 mm and a length of100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

21. The method of claim 19 or claim 20, wherein the first glass ply is annealed, fully thermally tempered, or semi-toughened.

22. The method of claim 19 or claim 20, wherein the first glass ply is ion-exchange strengthened.

23. The method of claim 22, wherein the first glass ply comprises a maximum central tension of 10 MPa or less.

24. The method of any one of claims 19-23, wherein the second glass ply is ion-exchange strengthened.

25. The method of claim 24, wherein the second glass ply comprises a compressive stress of at least 700 MPa.

26. The method of claim 25, wherein the laminate glazing is configured to withstand a load of at least 8000 N on the first major surface without failing as measured using a four- point bend test on a sample of the laminate glazing having a width of 50 mm and a length of 100 mm, the four-point bend test comprising two first side load points in contact with the first major surface of the first glass ply and two second side load points in contact with the fourth major surface, the two first side load points having a first span of 18 mm and the two second side load points having a second span of 36 mm, the first span and the second span being parallel to the length of the laminate glazing, the first side load points and the second side load points extending across the width of the sample, and the first side load points being driven toward the second side load points that are stationary.

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