Thin glass and method for producing thin glass

Abstract

The invention relates to a thin glass having a useful region with a thickness t of 15 to 300 µm and at least one side edge region, wherein the side edge region is designed in the form of a thickening with a maximum thickness Tmax, where 1<Tmax / t <10, and wherein the surface of the side edge region adjoins the useful region in a continuously curved manner. The invention also relates to a method for producing the thin glass.

Description

[0001] Applicant: SCHOTT AG, August 14, 2025

[0002] Our file: P06140 WO

[0003] - 1 -

[0004] Thin glass and methods for manufacturing thin glass

[0005] The invention relates to a thin glass with a thickness of 15 to 300 pm with high edge strength and a method for producing the thin glass.

[0006] Description

[0007] Thin glass is typically drawn from molten glass in vertical or horizontal drawing processes, forming ribbons. These ribbons have rims along their lateral edges that are significantly thicker than the actual usable area of ​​the glass. For very thin glass below approximately 300 µm, the thickness of the rim area is usually several times greater than the glass thickness in the middle of the ribbon. These thick rim areas are generally removed in a continuous process either during or after the cooling of the glass ribbon. Further processing of thin glass often requires cutting or separation, for which a variety of methods can be used, such as scoring, laser cutting, or the insertion of filaments along a dividing line with an ultrashort pulse laser, followed by breaking along the dividing line.The propagation of an initial crack by thermally induced tensile stresses using a CO2 laser is also known.

[0008] Many separation processes can lead to the formation of microcracks or other pre-existing damage at the separation edge of the thin glass. Under subsequent mechanical stress, this damage can result in a crack propagating into the thin glass. Tensile stresses at the edge can occur, for example, when the thin glass is bent along its convex outer edge.

[0009] Therefore, it is desirable to provide a method for increasing the edge strength of thin glass. Various methods for increasing the edge strength of thin glass are already known in the prior art. Edge strength can be increased using suitable mechanical grinding and polishing processes; however, such mechanical processes become increasingly difficult with decreasing thickness and intrinsic stability of thin glass, especially when high process speeds are required, which necessitates high forces. Similarly, the edge surface can be removed by an etching process, e.g., with hydrofluoric acid, but this is very time-consuming and material-intensive and requires subsequent cleaning of the thin glass to remove etching residues. Applicant: SCHOTT AG, August 14, 2025

[0010] Our file: P06140 WO

[0011] - 2 -

[0012] Edge processing of glass using gas torches is also known, but typically has many disadvantages. Gas flames are prone to flickering and instability, which directly affects the processing quality. Furthermore, gas torches emit environmentally harmful gases such as CO2 and, due to the high heat generated, always pose a risk of injury to production personnel in a manufacturing environment.

[0013] In the patent application KR20220035606, the treatment of the glass edge with a vacuum plasma is proposed, but the introduction of the thin glass into a vacuum is also very complex and inefficient.

[0014] In W02020 / 123226, it is proposed to treat the side surface of a glass article with an atmospheric pressure plasma generated by a plasma torch via a pulsed arc discharge at a frequency of 10 kHz to 1000 kHz. An increase in the flexural strength of the thin glass is disclosed, which is attributed to the generation of compressive stress in the edge surface. Plasmas using a gas with high thermal conductivity, such as helium or hydrogen, are said to be particularly advantageous. Typically, the treated edge can exhibit a SiO₂ content that is at least 10 mol% higher and an Al₂O₃ content that is at least 25 mol% lower. This results in a significant chemical modification of the glass surface, which can cause various problems in subsequent processes, as the chemically modified glass may exhibit altered properties with regard to chemical stability, thermal properties, and even crystallization.

[0015] The object of the present invention is to provide an efficient method for increasing the edge strength of a thin glass which does not have the disadvantages of the prior art, and to provide a thin glass with a correspondingly increased edge strength.

[0016] The problem is solved by the independent claims. Preferred embodiments are described in the dependent claims.

[0017] The thin glass according to the invention comprises a usable area and at least one side-edge area, wherein the thin glass in the usable area has a first main surface and a second main surface as well as a thickness t of 15 to 300 pm, wherein the side-edge area has a surface which connects the first main surface and the second main surface, wherein the side-edge area is in the form of a thickening with a maximum thickness T ma x with T max / t > 1 and a width W, the surface of the side edge region is continuously curved and connects to the first and second main surfaces, and where the ratio T ma x / t < 10. Applicant: SCHOTT AG, August 14, 2025

[0018] Our file: P06140 WO

[0019] - 3 -

[0020] The thin glass according to the invention can be produced using the inventive method, wherein the side edge region is melted by means of a plasma stream, the plasma stream being generated with an atmospheric pressure plasma torch which is generated by a high-frequency field in the frequency range of 500 MHz to 5 GHz, and wherein the plasma stream is moved along the untreated side edge region at a relative velocity v. The edge strength K of the thin glass can thereby be increased from an initial value K' to a higher value K.

[0021] The processed thin glass exhibits characteristic features.

[0022] The thin glass according to the invention exhibits a significantly improved edge strength K compared to untreated thin glass. Surprisingly, the highest edge strengths can be achieved when the side edge region is formed by a thickening with a maximum thickness T. ma x with T ma x / t > 1 and T ma x / t < 10 is formed.

[0023] The thin glass according to the invention thus has a secondary border which is significantly thinner and narrower than the border known to those skilled in the art, which results from the primary drawing process and which can be referred to as the primary border. Due to its very small thickness and width, this secondary border will also be referred to as the minimal border in the following.

[0024] Thin glass can be in the form of glass sheets or ribbons with a thickness of 15 µm to approximately 1 mm. Examples include SiO₂-based glasses such as borosilicate glasses, soda-lime glasses, and alkali-containing or alkali-free aluminosilicate glasses. Such thin glasses are typically produced from a glass melt via drawing processes such as downdraw, overflow fusion, or float processes, but can also be manufactured using cold finishing processes such as sawing, grinding, and polishing.

[0025] The thin glass can be in the form of a glass sheet with a rectangular, hexagonal, round, or any other freeform shape, or in the form of a glass ribbon, characterized by a length-to-width ratio of at least 10:1, preferably at least 50:1. Thin glass in the form of glass ribbons can also be in a rolled-up form, i.e., in the form of a glass roll.

[0026] According to the invention, the surface of the side edge region is continuously curved and adjoins the first and second main surfaces. "Continuously curved" here means that the thin glass exhibits a continuously changing curvature in a cross-sectional view perpendicular to the side edge region. Applicant: SCHOTT AG, August 14, 2025

[0027] Our file: P06140 WO

[0028] - 4 -

[0029] The usable area of ​​the thin glass is characterized by a thickness that is at least partially constant. Preferably, the two main surfaces have a roughness depth R. a < 1 nm, as is typically found on a fire-polished surface from a hot forming process.

[0030] The thin glass can have one or more side edge regions, e.g., an orthogonal basic shape with four side edge regions or a rounded shape with a single circumferential side edge region. At least one of the side edge regions is designed according to the invention, but in a preferred embodiment, two opposing side edge regions of a glass strip or glass sheet, or all four side edge regions of a glass strip or glass sheet, can also be designed according to the invention. In a further preferred embodiment, the glass sheet has a freeform or wafer shape (round shape with a notch or flattened edge for wafer alignment), wherein preferably the entire circumference of the thin glass is designed according to the invention.

[0031] Preferably, the side edge region designed according to the invention is at least partially straight; more preferably, the thin glass has two opposing and mutually parallel side edge regions designed according to the invention.

[0032] The maximum thickness T ma x and the width W of the side edge area may be subject to a range of variation along the side edge area. Unless otherwise specified, T ma x and W are determined as the mean of several individual measurements along a section of the side edge area.

[0033] The maximum thickness T can be determined in this case. max The thickness of the side edge can be determined at a specific point on the side edge, for example using a micrometer screw, or by means of a measuring microscope on a prepared cross-section or fracture. Typically, the thickness T is measured. max of the side edge area is determined as the mean value of 5 to 10 individual measurements distributed across the side edge area.

[0034] The width W of the lateral edge region is determined using a measuring microscope on a prepared cross-section or fracture. The boundary of the lateral edge region towards the functional area is defined by the fact that the thickness is significantly greater than in the functional area itself.

[0035] In a preferred embodiment, the ratio T is ma x / t < 5, preferably < 3, more preferably < 2 or < 1, 5 and / or T max / t >1.01, preferred > 1.05, more preferred > Applicant: SCHOTT AG 14.08.2025

[0036] Our file: P06140 WO

[0037] - 5 -

[0038] 1.10, and / or the W / t ratio < 50, preferably < 10, more preferably < 3. These embodiments are characterized by particularly high edge strength, and in these, the flexibility and pliability of the thin glass, which is present in a thicker side edge area with T, is largely eliminated. ma The bending radius (x / t > 5) is significantly restricted. The thin glass can thus, for example, be rolled up with a tight bending radius. Preferably, the ratio of the width W of the side edge region to the thickness t of the thin glass in the usable range is W / t < 100, preferably < 10, more preferably < 3. Surprisingly, such a small width or such a small ratio can be achieved with the method according to the invention, which allows for both the flexibility and pliability of the thin glass corresponding to the thinner usable range and also a large remaining usable range.

[0039] In a further preferred embodiment, the side edge region has a thickening with Tmax / t < 1.2 in combination with a width-to-thickness ratio W / t < 3, as well as rounded edges at the transition to the first and second main surfaces (2, 3). In a preferred embodiment, the surface of the side edge region has a roughness depth R over a surface area fraction of at least 10%, at least 30%, more preferably at least 80%, and most preferably completely. a < 2 nm or < 1 nm. A roughness depth of < 2 nm or even < 1 nm is characteristic of fire-polished glass surfaces. The area fraction of the glass surface with a roughness depth R aThe value < 2 nm thus reflects whether the side edge region has been only partially or completely melted. Therefore, preferably the side edge region is at least partially melted; preferably, a larger section of the side edge region or the entire surface of the side edge region is melted by the method according to the invention. The glass exhibits a roughness depth R at the melted surface of the side edge region. a < 2 nm. The term "roughness" used here refers to the average roughness R. a , which is a measure of the quality of a surface. Typically, amplitude parameters characterize the surface based on the vertical deviations of the roughness profile from the center line. R a This is the arithmetic mean of the absolute values ​​of these vertical deviations. The value can be determined according to DIN EN ISO 4287:2010-07.

[0040] In a further preferred embodiment, the side edge region in a cross-sectional view, with the exception of the adjoining usable area, is approximately circular and the width-to-thickness ratio W / t is typically >3, preferably Applicant: SCHOTT AG 14.08.2025

[0041] Our file: P06140 WO

[0042] - 6 -

[0043] 4. An approximately circular cross-sectional shape is understood here to be a cross-sectional shape that is convex over at least 200°, preferably at least 270°, with uniform curvature, and to which the usable area adjoins in the remaining section of the circumference. Advantages of this embodiment are the very reliable removal of microcracks in the side-edge region, as well as the stabilization of the thin glass by the thicker side-edge region, which results in the thin glass exhibiting higher inherent strength and improved handling overall.

[0044] In a preferred embodiment, the surface of the side edge region has two concavely curved sub-surfaces, each adjoining the first and second main surfaces, as well as a convexly curved sub-surface that connects the concavely curved sub-surfaces. This shape exhibits maximum strength and can advantageously be achieved with the plasma stream according to the invention.

[0045] The plasma flow according to the invention is characterized by a very high energy input combined with a low process gas flow. Thus, the molten glass is not displaced by the process gas flow, which would lead to rapid solidification of the molten glass in a colder area with uneven surface structures. Instead, the molten side edge area can form the described advantageous shape under the influence of the surface tension of the molten glass.

[0046] In a preferred embodiment, the side edge region in the convexly curved portion of the surface contains no tungsten, and preferably no other metals that are not part of the bulk glass composition of the thin glass. Tungsten or metals can cause problems in various thin glass applications, can reduce edge strength in particle form, and are therefore undesirable. While the use of an RF plasma torch based on a high-frequency arc discharge introduces tungsten or another electrode material into the glass surface, this can be avoided with the method according to the invention, since the plasma is generated not by means of an arc discharge, but solely via the microwave field.

[0047] The inventors have found that an undesirable chemical change in the convexly curved subsurface of the side edge area, which is most exposed to the atmospheric pressure plasma burner, can be prevented by the inventive method. Applicant: SCHOTT AG 14.08.2025

[0048] Our file: P06140 WO

[0049] - 7 - can be avoided. Such chemical changes are undesirable because they can, for example, lead to a change in the coefficient of thermal expansion of the thin glass in the edge region, which can, for example, lead to the build-up of mechanical stresses and a reduction in edge strength, or to other undesirable properties of the altered glass composition, such as reduced chemical resistance. A chemical change is understood to mean a deviation of the chemical composition of the thin glass from the bulk glass composition. A bulk glass composition corresponds to the composition of the thin glass in a central plane of the thin glass in the usable area, e.g., at a distance of at least 10 mm from the side edge region.This bulk glass composition can be determined, for example, in a cross-section through the thin glass using EDX, XPS, or another surface-sensitive measurement method. In a preferred embodiment, the SiO₂ content in a surface layer (measured with EDX) of the convexly curved sub-surface of the side edge region therefore deviates by less than 10 wt%, preferably less than 5 wt%, from the SiO₂ content of the bulk glass composition. Furthermore, in a preferred embodiment, the A₂O₃ content in a surface layer of the convexly curved sub-surface deviates by less than 10 wt%, preferably less than 5 wt%, from the A₂O₃ content of the bulk glass composition.

[0050] In a preferred embodiment, the surface of the side edge region exhibits bubble inclusions with an average size in the range of 0.5 to 5 pm, preferably at least 10 bubbles per 5 mm length of the side edge region. Such bubble inclusions can form, for example, if the untreated thin glass is previously separated by a laser filamentation process. In this process, laser filaments are introduced into the thin glass along a dividing line, and the glass is then fractured along the dividing line. Individual laser filaments, which result in low edge strength of the thin glass, can be sealed by the resulting glass melt, forming bubble inclusions. Surprisingly, these bubble inclusions do not reduce the edge strength.

[0051] In a preferred embodiment, the bulk glass composition has an Al₂O₃ content of at least 5 wt%, preferably at least 15 wt%, and / or a Na₂U content of at least 10 wt%, preferably at least 15 wt%. Such thin glasses can be characterized by chemical hardenability and are used, among other things, in the field of displays. Applicant: SCHOTT AG, August 14, 2025

[0052] Our file: P06140 WO

[0053] - 8 - In a preferred embodiment, the usable area of ​​the thin glass has a thickness t of 15 pm to 110 pm and / or a TTV of less than 15 pm, preferably less than 10 pm, and more preferably less than 5 pm and / or a relative TTV TTV rei of less than 15% preferably less than 10%, where TTV rei= TTV / t. The TTV (total thickness variation) is the difference between the maximum and minimum thickness in the usable area of ​​the thin glass. The inventors have found that small thickness variations in the untreated side edge area, as well as a small TTV, rei important for the formation of a side edge region of constant maximum thickness T ma x and are therefore also important for high edge strength of the thin glass.

[0054] In a preferred embodiment, the edge strength K of the thin glass after plasma treatment is at least 250 MPa, preferably at least 300 MPa and more preferably at least 400 MPa.

[0055] The edge strength K of the thin glass is determined using a two-point bending method, which is known, for example, from ST Gulati: “Two Point Bending of Thin Glass Substrate”, SID Symposium, Techn. Papers Vol. 42, pp. 652-654 (2011). In this method, a thin glass sample is clamped in a U-shape between two parallel support plates and bent ever more tightly by bringing these plates closer together. From the plate spacing at which fracture occurs, the fracture stress in the edge region of the thin glass is calculated, which was present at the time of fracture. In this description, the edge strength K denotes the arithmetic mean of the fracture stress values ​​determined by the two-point bending method for at least 10, preferably at least 20, thin glass samples.

[0056] The inventive method for producing thin glass with high edge strength comprises the following steps:

[0057] - Provision of an untreated thin glass, wherein the untreated thin glass comprises a usable area and an untreated side edge area with an untreated surface, wherein the untreated thin glass has an edge strength K' and has in the usable area a first main surface and a second main surface and a thickness t of 15 pm to 300 pm.

[0058] - Directing a plasma stream onto the untreated surface of the side edge area, wherein the plasma stream is generated with an atmospheric pressure plasma burner which is generated by a high frequency field in the frequency range of 500 MHz to 5 GHz.

[0059] - Moving the plasma stream along the untreated side edge area 10' with applicant: SCHOTT AG 14.08.2025

[0060] Our file: P06140 WO

[0061] - 9 - a relative velocity v, wherein the thin glass has an edge strength K after plasma treatment.

[0062] An untreated edge region is understood to be an edge region that has no thickening compared to the usable area of ​​the thin glass and is preferably formed essentially by a flat edge surface connecting the first and second main surfaces. The untreated edge region is preferably formed by separation processes such as diamond cutting, scoring, crack propagation by thermal stress, or similar separation processes known to those skilled in the art for separating the primary edge of a thin glass.

[0063] Surprisingly, the inventive method achieves a very rapid melting of the glass surface, which, on the other hand, does not introduce any new defects, impurities, or mechanical weaknesses. In particular, excessive melting of the thin glass can also be avoided, so that only a thin surface layer is melted.

[0064] In a preferred embodiment, the atmospheric pressure plasma burner has a radio frequency field between 1 GHz and 3 GHz, preferably between 2.3 and 2.5 GHz. Particularly powerful and cost-effective microwave generators exist in this frequency range. The microwave signal can be supplied to the burner head of the atmospheric pressure plasma burner either via a waveguide or via a suitable coaxial cable; the use of a coaxial cable allows for particularly flexible process control.

[0065] In a preferred embodiment, the atmospheric pressure plasma burner or microwave generator has a power input of 50 to 500 watts, preferably only 100 to 200 watts. The power can be delivered continuously or in pulses. The inventors have found that, surprisingly, even a very low power is sufficient to achieve the preferred edge shapes according to the invention. It is assumed that, firstly, the energy of the plasma is transferred very efficiently to the thin glass, and secondly, a very low gas flow of the process gas can be used, resulting in a very high energy flux density for the plasma and minimal heat dissipation by convection. Advantageously, the immediate vicinity of the plasma stream even remains cold. Applicant: SCHOTT AG, August 14, 2025

[0066] Our file: P06140 WO

[0067] - 10 -

[0068] Untreated or dried air can be used as the process gas supplied to the atmospheric pressure plasma burner, where it is converted into a plasma state. The use of H₂ or He, or any other process gas with a thermal conductivity greater than 0.1 W / (m K), can be advantageously avoided, especially since the use of H₂ poses a safety risk and the use of He is very expensive.

[0069] In a particularly preferred embodiment, the gas flow rate of the plasma stream is between 0.1 and 40 l / m, preferably between 2 and 15 l / m (l / m = standard liters per minute). With such a low gas flow rate, the plasma stream exhibits a very high energy density, and unwanted displacement or blowing of the molten glass can be avoided with a suitably adjusted burner opening. The thin glass then deforms essentially by minimizing its surface energy and typically forms the edge shape described above with a high surface quality.

[0070] The method according to the invention is preferably used for thin glass with a side edge region whose untreated surface has defects. A defect is understood to mean any irregularity in the untreated surface that reduces the edge strength, such as microcracks ("flaws"), laser filaments, or conchoidal fracture structures from previous cutting processes. The edge strength K' of the untreated thin glass is typically less than approximately 200 MPa.

[0071] Preferably, the untreated side edge region has a chamfered edge, more preferably a scribing-chopped edge. Such edges are characterized by characteristic fracture structures on the fracture surface as well as residues from the scribing, which can be carried out, for example, with a diamond or a carbide wheel. Likewise, the untreated side edge region can have a plurality of parallel laser filaments, which preferably extend over the entire thickness of the thin glass, with the fracture surface then extending between the laser filaments.

[0072] Such edges are also characterized by the fact that the untreated surface does not transition into the first main surface and / or second main surface with a continuous curvature, but preferably has sharp-edged overcuts.

[0073] The untreated side edge area has a thickness T ma x' on, where T max7t < 1.15, preferred; Tmax7t < 1.05, more preferred; T ma x7t -1 ,00. The untreated side edge area therefore preferably exhibits no thickening compared to the usable area. Applicant: SCHOTT AG 14.08.2025

[0074] Our file: P06140 WO

[0075] - 11 -

[0076] After plasma treatment, the thin glass exhibits at least one of the following features, as has already been described for the thin glass according to the invention.

[0077] - the side edge area is formed in the form of a thickening, wherein the ratio Tmax / t < 5, < 3, < 1.5, < 1.2, < 1.1 and / or Tmax / t > 1.04, preferably > 1.1

[0078] - the side edge area is formed in the form of a thickening, wherein the ratio W / t is < 100, preferably < 10, more preferably < 3.

[0079] - the side edge area has a thickening T max / t < 1, 2 and W / t < 3, as well as rounded edges at the transition to the first and second main surfaces (2, 3)

[0080] - the surface is completely fire-polished.

[0081] - the edge strength K is at least about 250 MPa, preferably at least 300 MPa and more preferably at least 400 MPa.

[0082] In the method according to the invention, the atmospheric pressure plasma torch is moved relative to the side edge region of the thin glass, whereby either the thin glass or the atmospheric pressure plasma torch can be moved. The plasma stream is directed towards the untreated surface of the side edge region. The distance between the atmospheric pressure plasma torch and the surface is preferably between 2 and 20 mm, more preferably between 4 and 15 mm.

[0083] The plasma stream can have an approximately cylindrical, jet-like shape with a visible length of approximately 20 to 50 mm. Unlike a burner flame, the plasma stream is typically very dimensionally stable, so that the plasma stream has a beam axis.

[0084] The direction from which the plasma stream strikes the side edge region can be described by two angles, a and β, where a is the angle between the beam axis of the plasma stream and the first main surface of the thin glass in a cross-sectional view perpendicular to the side edge region, and where β is the angle between the beam axis and a perpendicular on the side edge region in a top view of the first main surface. The angle a is preferably chosen to be less than 30°, preferably less than 10°, and the angle β less than 45°, preferably less than 15°. With a side edge surface perpendicular to the main surfaces, the plasma stream thus strikes the side edge surface almost perpendicularly. With these angles of incidence, side edge regions can be created in the form of thickenings with only a small width. Applicant: SCHOTT AG, August 14, 2025

[0085] Our file: P06140 WO

[0086] - 12 -

[0087] In a preferred embodiment of the process, the relative velocity v between the plasma stream and the thin glass is at least 1 m / min, preferably > 6 m / min, and particularly preferably between 12 and 30 m / min for a glass thickness of 30 to 50 pm. Particularly high process speeds are made possible by preheating the untreated thin glass before it comes into contact with the plasma stream, but this is relatively complex. Preferably, the untreated thin glass is not preheated before it comes into contact with the plasma stream.

[0088] The method according to the invention is thus characterized by numerous advantages over the prior art. The edge strength of a thin glass can be significantly improved by extremely rapid, at least partial, melting of a side edge region, wherein, according to the invention, the treated side edge region has a greater thickness than the thin glass, but can nevertheless have a minimal width and thickness. No metallic impurities are introduced, and the surface of the thin glass is not chemically altered or contaminated.

[0089] The invention is explained in more detail below with reference to the enclosed figures. These show:

[0090] Figure 1 Schematic cross-sectional view through the side edge region of the thin glass in a first embodiment

[0091] Figure 2 Photographic image of a fracture cross-section through the side edge region of the thin glass in a first embodiment with T / t ~ 1.5

[0092] Figure 3 Photographic image of a fracture cross-section through the side edge region of the thin glass in the first embodiment with T / t ~ 4

[0093] Figure 4 schematic cross-sectional view through the side edge region of an untreated thin glass

[0094] Figure 5a Photographic image of a fracture cross-section through the side edge region of an untreated thin glass with a scratch-broken edge

[0095] Figure 5b Photographic image of the side edge area of ​​an untreated thin glass with a scratched edge

[0096] Figure 5c Photographic image of the side edge area of ​​a (treated) thin glass with laser-filamentated and broken edge

[0097] Figure 6 Schematic representation of the process for producing thin glass

[0098] Figure 7 Dependence of the edge strength K of a thin glass treated according to the invention with a thickness of 30 pm as a function of the edge thickness Tmax Applicant: SCHOTT AG 14.08.2025

[0099] Our file: P06140 WO

[0100] - 13 -

[0101] Figure 1 shows a schematic cross-sectional view of the thin glass 1. The usable area 7 of the thin glass, with an approximately constant thickness t, adjoins the side edge area 10, which takes the form of a thickening with T. maThe side edge region 10 is formed with a curvature of x / t ~2 and a width W. The surface 4 of the side edge region 10 has two concave regions 8 that adjoin the usable region 7, as well as a convex region 9 that connects the two concave regions 8. The side edge region 10 is approximately circular, except for the adjoining usable region 7. The ratio of the width W of the side edge region 10 to the thickness t is approximately 2.5. The surface 4 of the side edge region 10 adjoins the first and second main surfaces 2, 3 of the usable region 7 with a continuously changing curvature.

[0102] Figures 2 and 3 show photographic images of a fracture cross-section through the side edge region of an embodiment with T / t ~ 1.5 (Figure 2) and with T / t ~ 4 (Figure 3), respectively.

[0103] Figure 4 shows a schematic cross-sectional view through the untreated side edge region 10' of a thin glass with an obliquely fractured edge. The side edge region 10' adjoins the usable area 7, has a maximum thickness corresponding to the glass thickness t and a width W', and an end face that connects sharply to the first and second main surfaces 2, 3, i.e., without a continuously changing curvature. Defects 20 are schematically indicated in the untreated surface 4'. For illustrative purposes, the fracture surface is shown obliquely.

[0104] Figures 5a and 5b show a photographic image of the fracture cross-section and a top view of the end face of an untreated thin glass 1 ' with a scribed, fractured edge, as it may be before the application of the inventive method.

[0105] Figure 5c shows a top-down photograph of an end face of thin glass produced by inserting equidistant laser filaments along a dividing line and subsequently fracturing along the dividing line. An untreated thin glass can also be in this form before the application of the inventive method. Applicant: SCHOTT AG, August 14, 2025

[0106] Our file: P06140 WO

[0107] - 14 -

[0108] Figure 6 shows a schematic representation of the process for producing thin glass with high edge strength.

[0109] Figure 7 shows the edge strength K as a function of the maximum thickness T. ma x of the side edge area for a thin glass sample with a glass thickness of approximately 30 pm.

[0110] Examples of implementation:

[0111] Small glass sheets measuring 50 mm x 30 mm were produced from a thin strip of chemically hardenable aluminosilicate glass with a thickness of approximately 30 pm using a slot-down draw process.

[0112] A first batch of thin glass samples was cut from glass ribbons using a scribing fracture process and exhibited an edge strength K of approximately 199 MPa + / - 23 MPa in a number of 36 samples.

[0113] A second batch of thin glass samples was produced using a laser filamentation process followed by fracturing along the filament line. These samples exhibited an edge strength / characteristic fracture strength / Weibull modulus of 182 MPa ± 17 MPa in a sample size of 34.

[0114] Subsequently, further samples from the first and second batches were treated using the inventive method. A Heuermann HF-Technik APP-Jet PC-PS 500 plasma torch, which can be operated with a power input of 100 to 500 watts, was used. Dried compressed air (5 bar) was supplied to the atmospheric pressure plasma torch as the process gas.

[0115] The thin-glass samples were positioned on a table so that a side edge of the thin glass extended beyond the table edge. The atmospheric pressure plasma torch was moved along the edge region, with the plasma stream directed towards the side edge at an angle α of 180° in the plane of the thin glass and perpendicular to the side edge at an angle β of 90° when viewed from above.

[0116] The following table lists the process parameters used: Applicant: SCHOTT AG 14.08.2025

[0117] Our file: P06140 WO

[0118] - 15 -

[0119] Process No.: #1 #2 #3 #4

[0120] Burner output [Watts] 120 130 120 120

[0121] Gas flow [l / min] 9 6 10 10

[0122] Freestanding glass overhang: 3 8 2.5 2.5

[0123] Working distance d [mm] 8.5 8 8.5 10

[0124] Angle a 180° 180 180° 180

[0125] Angle β 90° 90° 90° 90

[0126] Relative speed [rpm] 3000 3000 6m / min

[0127] Result:

[0128] Border diameter T ma x [pm] ~50 ~80 70 69

[0129] The average maximum thickness of the side edge area Tmax, the width W of the side edge area, and the edge strength K were determined on the processed glass samples.

[0130] Figure 7 shows the edge strength K as a function of the thickness T. maThe x and width W of the side edge area are shown. It can be seen that the edge strength could be significantly increased by the method according to the invention.

[0131] The edge strength K of the thin glass before carrying out the process according to the invention was 182 + / - 17 MPa. After carrying out the process according to the invention, the edge strength K has increased significantly and, depending on the thickness T, amounts to ma x of the secondary bore, at least 300 MPa, sometimes > 450 MPa.

[0132] Applicant: SCHOTT AG, August 14, 2025

[0133] Our file: P06140 WO

[0134] - 16 -

[0135] Reference symbol list

[0136] 1 (treated) thin glass

[0137] 1' untreated thin glass

[0138] 2 first main surface

[0139] 3 second main surface

[0140] 4 Surface (of the side edge area)

[0141] 4' Surface (of the untreated side edge area)

[0142] 7 Usable area

[0143] 8 concave curved partial surface

[0144] 9 convex curved partial surface

[0145] 10 side edge area

[0146] 10' untreated side edge area

[0147] 20 defects

[0148] 21. Bladder inclusion

[0149] 30 atmospheric pressure plasma burners

[0150] 31 Nozzle opening

[0151] 32 Plasma current

Claims

Applicant: SCHOTT AG, August 14, 2025 Our file: P06140 WO - 17 - Claims 1. Thin glass (1) comprising a usable area (7) and at least one side-edge area (10), wherein the thin glass in the usable area (7) has a first main surface (2) and a second main surface (3) and a thickness t of 15 to 300 pm, wherein the side-edge area (10) has a surface (4) which connects the first main surface (2) and the second main surface (3), wherein the side-edge area (10) is formed in the form of a thickening with a maximum thickness Tmax with Tmax / t > 1 and a width W, and wherein the surface (4) of the side-edge area (10) is continuously curved to the first (2) and second main surface (3), and wherein the ratio T ma x / t < 10.

2. Thin glass according to the preceding claim, wherein the thin glass comprises at least one of the following features: - the ratio T ma x / t is < 5, preferably < 3, more preferably < 2, or < 1.5 - the ratio T ma x / t is >1.01, preferably >1.05, more preferably >1.10 - the W / t ratio is < 50, preferably < 10, more preferably < 3.

3. Thin glass according to one of the preceding claims, wherein the side edge region (10) comprises at least one of the following features: - the side edge area (10) has a thickening with Tmax / t < 1,2 and W / t < 3, as well as rounded edges at the transition to the first and second main surface (2, 3) - the surface (4) of the side edge region (10) has a roughness depth R over a surface fraction of at least 10%, preferably at least 30%, more preferably at least 80% and most preferably completely. a < 2 nm or R a < 1 nm. - the side edge area (10) is approximately circular in a cross-sectional view, with the exception of the adjoining usable area (7).

4. Thin glass according to one of the preceding claims, wherein the surface (4) of the side edge region (10) has two concavely curved partial surfaces (8) which each adjoin the first (2) and second (3) main surface, and has a convexly curved partial surface (9) which connects the concavely curved partial surfaces (8).

5. Thin glass according to one of the preceding claims, wherein the side edge region (10) includes at least one of the following features: Applicant: SCHOTT AG, August 14, 2025 Our file: P06140 WO - 18 - - in the convexly curved partial surface (9) of the surface (4) no tungsten is present, preferably no metals at all, which are not part of the bulk glass composition of the thin glass. - a SiO2 content in a surface layer (measured by EDX) of the convexly curved sub-surface (9) deviates by less than 10 wt% from a SiO2 content of the bulk glass composition. - an AI2O3 content in a surface layer (measured by EDX) of the convexly curved sub-surface (9) deviates by less than 10 wt% from an AI2O3 content of the bulk glass composition. - the surface (4) of the side edge region (10) has bubble inclusions (21) with a mean size in the range of 0.5 to 5 pm, preferably at least 10 bubbles on a length of 5 mm of the side edge region (10).

6. Thin glass according to any one of the preceding claims, wherein the thin glass (1) comprises at least one of the following features - the bulk glass composition has an Al2O3 content of at least 5 wt%, preferably at least 15 wt% - the bulk glass composition has a Na2O content of at least 10 wt%, preferably at least 15 wt%.

7. Thin glass according to one of the preceding claims, wherein the usable area (7) of the thin glass (1) comprises at least one of the following features - a thickness t from 15 pm to 110 pm - a TTV (Total Thickness Variation) of less than 15 pm, preferably less than 10 pm, and preferably less than 5 pm - a relative Total Thickness Variation (TTV) rei of less than 15% preferably less than 10%, where TTV rei = TTV / t.

8. Thin glass according to one of the preceding claims, wherein the edge strength K' is at least 200 MPa, preferably at least 300 MPa and more preferably at least 400 MPa.

9. Method for producing thin glass with high edge strength, comprising the following steps: - Provision of an untreated thin glass (T), wherein the untreated thin glass (1') has a usable area (7) and an untreated side edge area (10') with a Applicant: SCHOTT AG, August 14, 2025 Our file: P06140 WO - 19 - untreated surface (4') comprising, wherein the untreated thin glass (1') has an edge strength K' and in the usable area (7) has a first main surface (2) and a second main surface (3) and a thickness t of 15 to 300 pm - Directing a plasma stream (32) onto the untreated surface (4') of the side edge region (13), wherein the plasma stream (32) is generated with an atmospheric pressure plasma burner (30) which is generated by a high frequency field in the frequency range of 500 MHz - 5 GHz - Moving the plasma stream (32) along the untreated side edge region 10' at a relative velocity v, wherein the thin glass has an edge strength K after plasma treatment.

10. The method according to claim 9, comprising at least one of the following features, - The atmospheric pressure plasma burner has a high-frequency field frequency between 1 GHz and 3 GHz, preferably between 2.3 and 2.5 GHz. - The atmospheric pressure plasma burner has a power consumption of 50 watts to 500 watts, preferably 100 to 200 watts. - The atmospheric pressure plasma burner uses untreated air or dried air as process gas. - The atmospheric pressure plasma burner uses as process gas a gas or gas mixture with a thermal conductivity of < 0.1 W / (m K), and preferably no H2 and no He - the gas flow of the plasma stream (32) is between 0.1 and 401 / min, preferably between 2 and 15 l / m.

11. Method according to any one of claims 9 to 10, wherein the untreated side edge region (10') comprises at least one of the following features, - the untreated surface (4') has defects (20) - the edge strength K' is less than approximately 200 MPa - the untreated side edge area (10') has a broken edge, preferably a scribed edge, - the untreated surface (4') does not transition into the first main surface (2) and / or second main surface (3) with a continuous curvature, but preferably with sharp edges - the untreated side edge area (10') has a thickness T ma x' on, where T ma x7t < 1.15, preferably T ma x7t < 1 ,05, more preferably Tmax' / t -1 ,00 is, - the untreated side edge area (10') shows no thickening compared to the usable area (7). Applicant: SCHOTT AG, August 14, 2025 Our file: P06140 WO - 20 - 12. Method according to any one of claims 9 to 11, wherein the thin glass (1) after plasma treatment has at least one of the following features: - the side edge region (10) is formed in the form of a thickening, wherein the ratio Tmax / t < 5, < 3, < 1.5, < 1.2, < 1.1 and / or Tmax / t > 1.04, preferably > 1.1 - the side edge region (10) is formed in the form of a thickening, wherein the ratio W / t < 100, preferably < 10, more preferably < 3. - the side edge area (10) has a thickening T ma x / t < 1 ,2 and W / t < 3, as well as rounded edges at the transition to the first and second main surface (2, 3) - the surface (4) is completely fire-polished. - the edge strength K is at least about 200 MPa, preferably at least 300 MPa and more preferably at least 400 MPa.

13. Method according to any one of claims 9 to 12, comprising at least one of the following features, - the distance between atmospheric pressure plasma burner (20) and surface (4') is between 2 and 20 mm, preferably between 4 and 15 mm. - the plasma stream has an approximately cylindrical, jet-like shape with a visible length of approximately 20 to 50 mm.

14. A method according to any one of claims 9 to 13, wherein the plasma stream has a beam axis (33), wherein the plasma stream strikes the side edge region (10') at angles α and β, wherein the angle α is the angle between the beam axis (33) and the first main surface (2) in a cross-sectional view perpendicular to the side edge region (10'), and wherein the angle β is the angle between the beam axis (33) and a perpendicular on the side edge region (10') in a top view of the first main surface (2), and wherein α is less than 30°, preferably less than 10°, and / or β is less than 45°, preferably less than 15°.

15. Method according to any one of claims 9 to 14, comprising at least one of the following features, - the relative velocity v between plasma stream and thin glass is at least 1 m / min, preferably at least 6 m / min, and more preferably even at least 12 m / min to 30 m / min for a glass thickness of 30 to 50 pm Applicant: SCHOTT AG, August 14, 2025 Our file: P06140 WO - 21 - - the untreated thin glass is not preheated before it comes into contact with the plasma stream.

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