Dimensionally stable glass

Abstract

Glasses that are substantially alkali-free and have high annealing points and therefore good dimensional stability (e.g., low compaction) for use as TFT backplane substrates in amorphous silicon, oxide, and low-temperature polysilicon TFT processes.

Description

Description of Related Applications

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62 / 736,070, filed on September 25, 2018, the content of which is relied upon and incorporated herein in its entirety.

Technical Field

[0002] Embodiments of the present disclosure utilize an unexpected combination of viscosity curves and high liquid-phase viscosities that enable glass meeting specific threshold values of customer-facing attributes to be manufactured at better cost and quality than any previously disclosed glass composition.

Background Art

[0003] The manufacture of liquid crystal displays, such as active matrix liquid crystal display (AMLCD) devices, is very complex, and the properties of the substrate glass are important. First and foremost, the glass substrates used in the manufacture of AMLCD devices need to have tightly controlled physical dimensions. The down-draw sheet stretching method, and particularly the fusion method described in both Dockerty's Patent Documents 1 and 2, can produce glass sheets that can be used as substrates without the need for costly post-forming finishing operations such as lapping and polishing. Unfortunately, this fusion method imposes fairly stringent limitations on glass properties, and for that reason, a relatively high liquid-phase viscosity is required.

[0004] In the field of liquid crystal displays, thin film transistors (TFTs) based on polycrystalline silicon are preferred due to their ability to transport electrons more effectively. Polycrystalline silicon transistors (p-Si) are characterized as having higher mobility than those based on amorphous silicon transistors (a-Si). This allows for the production of smaller and faster transistors, which ultimately results in the production of brighter and faster displays.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] U.S. Patent No. 3,338,696 [Patent Document 2] U.S. Patent No. 3,682,609 [Overview of the project]

[0006] One or more embodiments of the present disclosure provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 66 to 70.5% SiO2, 11.2 to 13.3% Al2O3, 2.5 to 6% B2O3, 2.5 to 6.3% MgO, 2.7 to 8.3% CaO, 1 to 5.8% SrO, and 0 to 3% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent mole percent of oxide components. Further embodiments include an RO / Al2O3 ratio of 0.98 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.38 or an MgO / RO ratio of 0.18 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.45. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical clarifier. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical clarifier. Some embodiments may have a slow-cooling point above 750°C, above 765°C, or above 770°C. Some embodiments may have a liquid-phase viscosity above 100,000 poise, above 150,000 poise, or above 180,000 poise. Some embodiments may have a Young's modulus above 80 GPa, above 81 GPa, or above 81.5 GPa. Some embodiments may have a density of less than 2.55 g / cc, less than 2.54 g / cc, or less than 2.53 g / cc. Some embodiments may have a T200P of less than 1665°C, less than 1650°C, or less than 1640°C. Some embodiments may have a T35kP of less than 1280°C, less than 1270°C, or less than 1266°C. Some embodiments may have a T200P-T(ann) of less than 890°C, less than 880°C, less than 870°C, or less than 865°C. Some embodiments may have a T200P-T(ann) of less than 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise.Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof account for less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. The exemplary objects made from these glass materials can be manufactured by down-draw sheet manufacturing, fusion, or variations thereof.

[0007] Some embodiments provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 68–79.5% SiO2, 12.2–13% Al2O3, 3.5–4.8% B2O3, 3.7–5.3% MgO, 4.7–7.3% CaO, 1.5–4.4% SrO, and 0–2% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.2 or an MgO / RO ratio of 0.24 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.36. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent. Some embodiments may have a T200P-T(ann) below 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise. Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, a T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 constitute less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method or a fusion method or a variation thereof.

[0008] Some embodiments provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 68.3–69.5% SiO2, 12.4–13% Al2O3, 3.7–4.5% B2O3, 4–4.9% MgO, 5.2–6.8% CaO, 2.5–4.2% SrO, and 0–1% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.09 ≤ (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.16 or an MgO / RO ratio of 0.25 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.35. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent. Some embodiments may have a T200P-T(ann) below 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise. Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, a T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 constitute less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method or a fusion method or a variation thereof.

[0009] Some embodiments provide a glass having a Young's modulus in the range defined by the relation: 70 GPa ≤ 549.899 - 4.811 * SiO2 - 4.023 * Al2O3 - 5.651 * B2O3 - 4.004 * MgO - 4.453 * CaO - 4.753 * SrO - 5.041 * BaO ≤ 90 GPa, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percentages of the oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2. Some embodiments may contain any one or combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as chemical fining agents at 0.01 to 0.4 mol%. Some embodiments may contain any one or combination of Fe2O3, CeO2, or MnO2 as chemical fining agents at 0.005 to 0.2 mol%. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof accounts for less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass for each raw material utilized. Exemplary objects made from these glasses can be manufactured by the down-draw sheet manufacturing method or the fusion method or variants thereof.

[0010] Some embodiments provide a glass having a Young's modulus in the range defined by the relation: 720 °C ≤ 1464.862 - 6.339 * SiO2 - 1.286 * Al2O3 - 17.284 * B2O3 - 12.216 * MgO - 11.448 * CaO - 11.367 * SrO - 12.832 *The provided glass has an annealing point in the range defined by BaO ≤ 810°C, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the molar percentages of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2. Some embodiments may also contain 0.01 to 0.4 mol% of SnO2, As2O3, or Sb2O3, F, Cl, or Br as chemical fining agents. Some embodiments may also contain 0.005 to 0.2 mol% of Fe2O3, CeO2, or MnO2 as chemical fining agents. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than approximately 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method, a fusion method or a variation thereof.

[0011] Additional embodiments of this disclosure relate to objects made from glass produced by a down-draw sheet manufacturing method. Further embodiments relate to glass produced by a fusion method or a variation thereof.

[0012] The attached drawings are included in this specification and constitute part thereof, illustrating several embodiments described below. [Brief explanation of the drawing]

[0013] [Figure 1] Schematic diagram of a molded mandrel used to manufacture precision sheets in the fusion drawing method. [Figure 2] Cross-sectional view of the molded mandrel in Figure 1, taken along position 6. [Figure 3] Graph of a convex hull according to some embodiments of the present disclosure [Figure 4]Graph of a convex hull relating to other embodiments of the present disclosure [Figure 5] Graph of a convex hull relating to additional embodiments of the present disclosure [Figure 6] Graph of a convex hull relating to further embodiments of the present disclosure [Figure 7] Graph representation of equation (1) for several randomly selected embodiments located within the convex hull of Figure 3. [Figure 8] Graph representation of equation (2) for several randomly selected embodiments located within the convex hull of Figure 3. [Modes for carrying out the invention]

[0014] One of the problems with p-Si transistors is that their manufacture requires higher process temperatures than those used for a-Si transistors. These temperatures range from 450°C to 600°C, compared to the peak temperature of 350°C used for a-Si transistor manufacturing. At these temperatures, most AMLCD glass substrates undergo a process known as compaction. Also called thermal stability or dimensional change, compaction is an irreversible dimensional change (shrinkage) in a glass substrate due to a change in the virtual temperature of the glass. "Virtual temperature" is a concept used to describe the structural state of glass. Glass that is rapidly cooled from a high temperature is said to have a higher virtual temperature due to a higher-temperature structure that is "frozen in". Glass that is cooled more slowly, or slowly cooled by being held near its annealing point for a period of time, is said to have a lower virtual temperature.

[0015] The degree of consolidation depends on both the glass manufacturing process and the viscoelastic properties of the glass. In the float process for producing sheet products from glass, the glass sheet cools relatively slowly from the molten state and therefore "freezes" into a relatively low-temperature structure. In contrast, in the fusion process, the glass sheet cools very rapidly from the molten state and freezes into a relatively high-temperature structure. As a result, since the driving force for consolidation is the difference between the virtual temperature and the process temperature the glass goes through during consolidation, glass produced by the float process will undergo less compression than glass produced by the fusion process. Therefore, it is desirable to minimize the level of consolidation in glass substrates produced by the down-draw process.

[0016] There are two methods to minimize compaction in glass. The first method involves thermally pre-treating the glass to create a virtual temperature similar to that the glass experiences during p-Si TFT manufacturing. This method has several drawbacks. Firstly, the numerous heating steps used during p-Si TFT manufacturing create slightly different virtual temperatures in the glass that cannot be completely compensated for by this pre-treatment. Secondly, the thermal stability of the glass becomes closely related to the details of its p-Si TFT manufacturing, which may mean different pre-treatments for different end users. Finally, pre-treatment increases the cost and complexity of processing.

[0017] Another approach is to slow the strain rate at the process temperature by increasing the viscosity of the glass. This can be achieved by increasing the viscosity of the glass. The annealing point represents the temperature at which the glass has a fixed viscosity; therefore, an increase in the annealing point is equivalent to an increase in viscosity at a fixed temperature. However, the challenge of this approach is the cost-effective production of glass with a high annealing point. The main factors affecting the cost are defects and the lifespan of the asset. In conventional melting equipment coupled to fusion drawing equipment, four types of defects are commonly encountered: (1) gaseous inclusions (bubbles or blisters), (2) solid inclusions due to the inability to properly melt the refractory or batch, (3) metallic defects consisting mainly of platinum, and (4) devitrification products resulting from low liquid-phase viscosity or excessive devitrification at both ends of the isopipe. The glass composition has an unbalanced influence on the melting rate and, therefore, the tendency of the glass to form gaseous or solid defects, and the oxidation state of the glass influences the tendency to include platinum defects. Devitrification of glass on the molding mandrel, i.e., the isopipe, is best controlled by selecting a composition with high liquid-phase viscosity.

[0018] The service life of an asset is primarily determined by the rate of wear or deformation of the various refractory and precious metal components of the melting and forming system. Recent advances in refractory materials, platinum system design, and isopipe refractories present the potential to significantly extend the useful operating life of conventional melting equipment connected to fusion draw apparatus. Consequently, the life-limiting component of conventional fusion draw melting and forming platforms is the electrode used to heat the glass. Tin oxide electrodes corrode slowly over time, and the corrosion rate is a strong function of both temperature and glass composition. To maximize the service life of the asset, it is desirable to identify a composition that reduces the corrosion rate of the electrode while maintaining the attributes that limit the aforementioned defects.

[0019] Alkali-free glass having a high annealing point and therefore good dimensional stability (i.e., low compaction), and a method for producing the same are described herein. In addition, the exemplary compositions have very high liquid-phase viscosity, and therefore the possibility of devitrification on the forming mandrel is reduced or eliminated. As a result of the specific details of these compositions, the exemplary glasses melt to good quality with very low levels of gaseous inclusions and minimal corrosion to noble metals, refractories, and tin oxide electrode materials.

[0020] The embodiments described herein maintain excellent total pitch accuracy (TPV) while improving manufacturability and cost compared to the existing Lotus® glass family. This is achieved through a unique combination of viscosity curves with high liquid-phase viscosity, while maintaining density and CTE within conventionally desirable ranges for display applications. Conventional glasses with moderate annealing points may have exhibited some of these attributes, but not all simultaneously, which results in a unique and unexpected compositional range.

[0021] Substantially alkali-free glass with a high annealing point and therefore good dimensional stability (i.e., low consolidation) is disclosed herein for use as a TFT backplane substrate in amorphous silicon, oxide, and low-temperature polysilicon TFT processes. Suitable uses for high-performance displays using a-Si and oxide-TFT technologies have also been found for the exemplary glass described herein. Glass with a high annealing point can prevent panel distortion due to consolidation / shrinkage or stress relaxation during thermal processing after the glass is manufactured. The disclosed glass has the additional features of relatively low melting and clarification temperatures due to its viscosity curve. For glass with such a viscosity curve, the exemplary glass also has an unusually high liquid-phase viscosity and therefore a significantly reduced risk of devitrification in cold places in the molding apparatus. While low alkali concentrations are generally desirable, it should be understood that in practice, it may be difficult or impossible to economically manufacture completely alkali-free glass. The alkali in question arises as contaminants in the raw materials, trace components in refractories, etc., and can be very difficult to eliminate completely. Therefore, the example glass is considered substantially alkali-free if the total concentration of alkali elements Li2O, Na2O, and K2O is less than approximately 0.1 mole percent (mol%).

[0022] In one embodiment, a substantially alkali-free glass has an annealing point greater than about 750°C, greater than 765°C, or greater than 770°C. Such a high annealing point gives a low relaxation rate (by either consolidation, stress relaxation, or both) and therefore small dimensional changes, in order to enable the use of the exemplary glass as a backplane substrate or support. In another embodiment, at a viscosity of 35,000 poise, the exemplary glass has a corresponding temperature (T35kP) less than about 1280°C, less than 1270°C, or less than 1266°C. The liquidus temperature (T35kP) of the glass liq) is the highest temperature above which the crystalline phase cannot coexist in equilibrium with the glass. In another embodiment, the viscosity corresponding to the liquidus temperature of the glass is greater than about 100,000 poise, greater than about 150,000 poise, or greater than about 180,000 poise. In another embodiment, with a viscosity of 200 poise, the exemplary glass has a corresponding temperature (T200P) of less than about 1665°C, less than 1650°C, or less than 1640°C. In another embodiment, the exemplary glass has a temperature difference between T200P and the annealing point (T(ann)) of less than 890°C, less than 880°C, less than 870°C, or less than 865°C.

[0023] In one or more embodiments, the substantially alkali-free glass contains, in mole percent on an oxide basis, 66-70.5% SiO2, 11.2-13.3% Al2O3, 2.5-6% B2O3, 2.5-6.3% MgO, 2.7-8.3% CaO, 1-5.8% SrO, and 0-3% BaO, with 0.98 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.38 and 0.18 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.45, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0024] In further embodiments, the substantially alkali-free glass contains, in mole percent on an oxide basis, 68-69.5% SiO2, 12.2-13% Al2O3, 3.5-4.8% B2O3, 3.7-5.3% MgO, 4.7-7.3% CaO, 1.5-4.4% SrO, and 0-2% BaO, with 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2 and 0.24 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.36, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0025] In further embodiments, the substantially alkali-free glass contains, in mole percent on an oxide basis, 68.3–69.5% SiO2, 12.4–13% Al2O3, 3.7–4.5% B2O3, 4–4.9% MgO, 5.2–6.8% CaO, 2.5–4.2% SrO, and 0–1% BaO, with 1.09 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.16 and 0.25 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.35, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0026] In one embodiment, the exemplary glass contains a chemical fining agent. Examples of such fining agents include, but are not limited to, SnO2, As2O3, Sb2O3, F, Cl, and Br, and the concentration of the chemical fining agent is maintained at a level of 0.5 mol% or less. Other oxides of transition metals such as CeO2, Fe2O3, and MnO2 may also be used as chemical fining agents. These oxides may impart color to the glass due to visible absorption in the final valence state within the glass; therefore, their concentration may be maintained at a level of 0.2 mol% or less.

[0027] In one embodiment, the exemplary glass is manufactured in sheet form by a fusion drawing method. This fusion drawing method results in a clean, fire-finished glass surface that reduces surface-mediated distortion for high-resolution TFT backplanes and color filters. Figure 1 is a schematic diagram of the fusion drawing method at the position of a forming mandrel, or isopipe, so named because its sloping trough design produces the same (hence "iso") flow at all points along its length (from left to right). Figure 2 is a schematic cross-sectional view of an isopipe near position 6 in Figure 1. Glass is introduced from the inlet 1 and flows along the bottom 4 of the trough, formed by the weir wall 9, to the compression end 2. The glass overflows from the weir wall 9 on both sides of the isopipe (see Figure 2), and the two flows of glass join or fuse at the base 10. Edge directors 3 at both ends of the isopipe serve to cool the glass and create a thicker piece called a bead at the edge. The bead is pulled downwards by the traction roll, thus enabling sheet formation at high viscosity. By adjusting the speed at which the sheet is drawn out of the isopipe, the fusion draw method can be used to produce a very wide range of thicknesses at a constant melting rate.

[0028] The down-draw sheet stretching method, and in particular the fusion method described in Patent Documents 1 and 2 (both Dockerty) cited herein, can be used. Compared to other forming methods such as the float method, the fusion method is preferred for several reasons. Firstly, glass substrates produced by the fusion method do not require polishing. Polishing of current glass substrates can produce glass substrates with an average surface roughness (Ra) greater than about 0.5 nm, as measured by atomic force microscopy. Glass substrates produced by the fusion method have an average surface roughness of less than 0.5 nm, as measured by atomic force microscopy. The substrate also has an average internal stress of 150 psi (about 1.03 MPa) or less, as measured by optical delay.

[0029] In one embodiment, the exemplary glass is manufactured in sheet form using a fusion process. While the exemplary glass is adapted to the fusion process, they may also be manufactured in sheets or other goods by less stringent manufacturing methods. Such methods include slot-draw, float-formation, rolling, and other sheet forming methods known to those skilled in the art. Thus, the embodiments described herein are not limited to the fusion process, but are equally applicable to other forming methods such as float-formation.

[0030] Compared to these alternative methods for forming glass sheets, the fusion method, as described above, can produce very thin, very flat, and very uniform sheets with a clean surface. While the slot-draw method can also produce a clean surface, the dimensional uniformity and surface quality of glass produced by the slot-draw method are generally inferior to that of glass produced by the fusion-draw method due to changes in orifice shape over time, accumulation of volatile debris at the orifice-glass interface, and the challenge of creating an orifice to supply truly flat glass. The float method can supply very large, uniform sheets, but its surface is substantially damaged by contact with the float bath on one side and exposure to condensation products from the float bath on the other side. This means that float glass must be polished for use in high-performance display applications.

[0031] Unlike the float process, the fusion process results in a rapid cooling of the glass from a high temperature, which gives rise to a high fictive temperature Tf. This fictive temperature can be considered to represent the difference between the structural state of the glass and the state if it were fully relaxed at the temperature of interest. Here, we consider the result of the process of reheating a glass having a glass transition temperature Tg to a process temperature Tp such that Tp < Tg ≤ Tf. Since Tp < Tf, the structural state of the glass is out of equilibrium at Tp, and the glass spontaneously relaxes to an equilibrium structural state at Tp. This relaxation rate is inversely proportional to the effective viscosity of the glass at Tp, and thus a high viscosity results in a slow relaxation rate and a low viscosity results in a fast relaxation rate. The effective viscosity varies inversely with the fictive temperature of the glass, and thus a low fictive temperature results in a high viscosity and a high fictive temperature results in a relatively low viscosity. Therefore, the relaxation rate at Tp is directly related to the fictive temperature of the glass. The process of introducing a high fictive temperature results in a relatively high relaxation rate when the glass is reheated at Tp.

[0032] One means of reducing the relaxation rate at Tp is to increase the viscosity of the glass at that temperature. The annealing point of the glass represents the temperature at which the glass has a viscosity of 10 13.2 poises. As the temperature drops below the annealing point, the viscosity of the supercooled melt increases. At a fixed temperature below Tg, the glass with a higher annealing point has a higher viscosity than the glass with a lower annealing point. Thus, one might choose to increase the annealing point of the substrate glass in order to increase its viscosity at Tp. Unfortunately, in general, the compositional changes necessary to increase the annealing point also increase the viscosity at all other temperatures. Specifically, the fictive temperature of glass produced by the fusion process is about 10 11 ~10 12The virtual temperature corresponds to the viscosity of Poise, and therefore, increasing the annealing point of a glass suitable for the fusion process generally increases its virtual temperature as well. For a given glass, the higher the virtual temperature, the lower the viscosity at temperatures below Tg; therefore, increasing the virtual temperature works in opposition to the viscosity increase that would otherwise be obtained by increasing the annealing point. To observe a substantial change in the relaxation rate at Tp, it is generally necessary to change the annealing point relatively significantly. Embodiments of the exemplary glass have annealing points above approximately 750°C, above 765°C, or above 770°C. While not bound by any particular theory of the operation, such high annealing points are thought to result in acceptablely low rates of thermal relaxation during suitable cycles in low-temperature TFT processing, such as a typical low-temperature polysilicon fast thermal annealing cycle or oxide TFT processing.

[0033] Increasing the annealing point increases the temperature of the entire melting and molding system, particularly the temperature on the isopipe, in addition to its effect on the virtual temperature. For example, "Eagle XG" and "Lotus" (Corning Incorporated, Corning, New York) have annealing points that differ by about 50°C, and the temperatures at which they are supplied to the isopipe also differ by about 50°C. Zircon refractories exhibit thermal creep when held at high temperatures for extended periods, which can be accelerated by the mass of the glass on the isopipe as well as the mass of the isopipe itself. A second embodiment of the exemplary glass has an annealing point above 750°C while its supply temperature is below 1280°C. Such a supply temperature allows for extended manufacturing campaigns without replacing the isopipe, and the high annealing point allows the glass to be used in the manufacture of high-performance displays, such as those due to oxide TFT or LTPS processes.

[0034] In addition to this criterion, the fusion process typically involves glasses with high liquidus viscosity. This is necessary to avoid devitrification products at the interface with the glass and to minimize visible devitrification products in the final glass. Adjusting the process to produce wider or thicker sheets for a given glass that is suitable for fusion of a specific sheet size and thickness generally results in lower temperatures at both ends of the isopipe (forming mandrel for the fusion process). Therefore, exemplary glasses with high liquidus viscosity can offer greater flexibility in manufacturing by the fusion process.

[0035] For formation by the fusion method, it is desirable that the exemplary glass compositions have a liquidus viscosity of 130,000 poise or more, 150,000 poise or more, or 200,000 poise or more. An unexpected result is that, across the entire range of exemplary glasses, sufficiently low liquidus temperatures and sufficiently high viscosities can be obtained, such that the liquidus viscosity of the glass is unusually high compared to compositions outside the exemplary range.

[0036] In the glass compositions described herein, SiO2 acts as a basic glass-forming agent. In certain embodiments, the concentration of SiO2 may be 66 mol percent or higher to give the glass a density and chemical durability suitable for flat panel display glass (e.g., AMLCD glass), and a liquidus temperature (or liquidus viscosity) that allows the glass to be formed by a down-draw method (e.g., fusion method). With respect to the upper limit, the concentration of SiO2 may generally be about 70.5 mol percent or lower to allow batch material to be melted using conventional mass melting techniques, e.g., Joule melting in a refractory melting apparatus. As the concentration of SiO2 increases, the 200 poise temperature (melting temperature) generally increases. In various applications, the concentration of SiO2 is adjusted so that the glass composition has a melting temperature of 1665°C or lower. In one embodiment, the concentration of SiO2 is between 66 mol percent and 70.5 mol percent.

[0037] Al2O3 is another glass-forming material used in the manufacture of the glass described herein. An Al2O3 concentration of 11.2 mol percent or higher gives the glass a low liquidus temperature and high viscosity, resulting in high liquidus viscosity. Using at least 12 mol percent of Al2O3 also improves the annealing point and Young's modulus of the glass. It is desirable to maintain the Al2O3 concentration below approximately 13.3 mol percent in order that the ratio (MgO+CaO+SrO+BaO) / Al2O3 is 0.98 or higher. In one embodiment, the Al2O3 concentration is between approximately 11.2 mol percent and 13.3 mol percent, and in other embodiments, this range is maintained while keeping the (MgO+CaO+SrO+BaO) / Al2O3 ratio 0.98 or higher.

[0038] B2O3 is both a glass-forming agent and a flux that promotes melting and lowers the melting temperature. Its effect on liquidus temperature is at least as significant as its effect on viscosity; therefore, increasing the B2O3 content can be used to increase the liquidus viscosity of the glass. To maximize the liquidus viscosity of these glasses, the glass compositions described herein have a B2O3 concentration of 2.5 mol percent or higher. As previously mentioned with respect to SiO2, the durability of the glass is very important for LCD applications. Durability can be controlled to some extent by an increased concentration of alkaline earth oxides and can be significantly reduced by an increased B2O3 content. The annealing point, like Young's modulus, decreases as B2O3 increases; therefore, it is desirable to maintain a low B2O3 content compared to the typical concentration in amorphous silicon substrates. For this reason, in one embodiment, the glass described herein has a B2O3 concentration between 2.5 mol percent and 6 mol percent.

[0039] The concentrations of Al2O3 and B2O3 can be selected in pairs to increase the annealing point, increase the modulus, improve durability, decrease density, and reduce the coefficient of thermal expansion (CTE) while maintaining the melting and molding properties of the glass.

[0040] For example, an increase in B2O3 and a corresponding decrease in Al2O3 may help maintain lower density and CTE, whereas an increase in Al2O3 and a corresponding decrease in B2O3 may help increase the slow cooling point, modulus, and durability, provided that the (MgO+CaO+SrO+BaO) / Al2O3 ratio does not decrease below approximately 1.0. For (MgO+CaO+SrO+BaO) / Al2O3 ratios below approximately 1.0, it will be difficult or impossible to remove gaseous inclusions from the glass due to the late melting of the silica raw materials. Furthermore, if (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.05, mullite, which is an aluminosilicate crystal, may appear as a liquid phase. Once mullite is present as a liquid phase, the compositional sensitivity of the liquidus line increases significantly, and mullite devitrification products grow very rapidly and, once formed, are very difficult to remove. Therefore, in one embodiment, the glass described herein has (MgO+CaO+SrO+BaO) / Al2O3≧1.05. Additionally, an example of glass used for AMLCD applications is 28~42×10 -7 / ℃, 30~40×10 -7 / ℃, or 32-38 × 10 -7 It has a coefficient of thermal expansion (CTE) within the range of / °C (22~300°C).

[0041] The glass described herein includes alkaline earth oxides in addition to glass-forming materials (SiO2, Al2O3, and B2O3). In one embodiment, at least three alkaline earth oxides, e.g., MgO, CaO, and BaO, and optionally SrO, are part of the glass composition. In another embodiment, SrO is used instead of BaO. In yet another embodiment, all four—MgO, CaO, SrO, and BaO—are present. The alkaline earth oxides impart various properties to the glass that are important for melting, clarification, shaping, and end-use. Therefore, to improve the glass performance in these respects, in one embodiment, the ratio of (MgO+CaO+SrO+BaO) / Al2O3 is 1.05 or greater. As this ratio increases, the viscosity tends to decrease more strongly than the liquidus temperature, and thus it becomes increasingly difficult to obtain a sufficiently high value of liquidus viscosity. Therefore, in another embodiment, the ratio (MgO+CaO+SrO+BaO) / Al2O3 is 1.38 or less.

[0042] In certain embodiments, alkaline earth oxides are sometimes treated as virtually single components. This is because their effects on viscoelastic properties, liquidus temperature, and liquidus relationship are qualitatively more similar to those of the glass-forming oxides SiO2, Al2O3, and B2O3. However, while the alkaline earth oxides CaO, SrO, and BaO can form solid solutions with feldspar minerals, particularly anorthite (CaAl2Si2O8) and celsian (BaAl2Si2O8) and the same strontium, MgO does not significantly contribute to these crystals. Therefore, if the feldspar crystals are already in the liquid phase, the addition of MgO will stabilize the liquid relative to the crystals and thus lower the liquidus temperature. At the same time, the viscosity curve will generally become steeper, lowering the melting temperature with little or no effect on the low-temperature viscosity. In the sense described above, the addition of a small amount of MgO is advantageous for molding by lowering the liquidus temperature and increasing the liquidus viscosity, while maintaining a high annealing point and therefore low compaction, and is also advantageous for melting by lowering the melting temperature. Thus, in various embodiments, the glass composition contains MgO in an amount ranging from about 2.5 mole percent to about 6.3 mole percent.

[0043] A surprising result from investigating the trend of the liquidus line in glasses with high annealing points is that, for glasses with appropriately high liquidus viscosity, the ratio of MgO to other alkaline earth oxides, MgO / (MgO+CaO+SrO+BaO), falls within a relatively narrow range. As mentioned earlier, the addition of MgO destabilizes the feldspar minerals, thus stabilizing the liquid and potentially lowering the liquidus temperature. However, once MgO reaches a certain level, mullite Al6Si2O 13The mixture will be stabilized, and therefore the liquid phase temperature will rise and the liquid phase viscosity will decrease. Furthermore, higher concentrations of MgO tend to decrease the viscosity of the liquid, and therefore, even if the liquid phase viscosity remains unchanged by the addition of MgO, it will eventually decrease. Therefore, in another embodiment, 0.18 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.45. MgO may be substituted for glass-forming agents and other alkaline earth oxides within this range to maximize the value of the liquid phase viscosity, in accordance with obtaining other desired properties.

[0044] The calcium oxide present in the glass composition can produce a low liquidus temperature (high liquidus viscosity), a high annealing point and Young's modulus, and a CTE in the range most desirable for flat panel applications, particularly AMLCD applications. Its presence also contributes favorably to chemical durability, and compared to other alkaline earth oxides, it is relatively inexpensive as a batch material. However, at high concentrations, CaO increases density and CTE. Furthermore, at sufficiently low SiO2 concentrations, CaO can stabilize anorthite and thus reduce liquidus viscosity. Therefore, in one embodiment, the concentration of CaO may be 4 mole percent or more. In another embodiment, the concentration of CaO in the glass composition is between approximately 2.7 mole percent and 8.3 mole percent.

[0045] Both SrO and BaO can contribute to a low liquidus temperature (high liquidus viscosity), and therefore, the glasses described herein typically contain at least both of these oxides. However, the selection and concentration of these oxides are chosen to avoid increases in CTE and density, and decreases in modulus and annealing point. The relative ratio of SrO and BaO can be balanced to obtain a suitable combination of physical properties and liquidus viscosity so that the glass can be molded by the down-draw method, and their total concentrations are between 1 mol% and 9 mol%. In some embodiments, the glass contains SrO in the range of about 1 mol% to about 5.8 mol%. In one or more embodiments, the glass contains BaO in the range of about 0 mol% to about 3 mol%.

[0046] To summarize the effects / roles of the central components of the glass of this disclosure, SiO2 is the basic glass-forming material. Al2O3 and B2O3 are also glass-forming materials and can be selected in pairs. For example, increasing B2O3 and decreasing Al2O3 is used to obtain lower density and CTE, while increasing Al2O3 and decreasing B2O3 is used to increase the annealing point, Young's modulus, and durability, provided that the RO / Al2O3 ratio, RO=(MgO+CaO+SrO+BaO), does not decrease to less than approximately 1. If this ratio becomes too low, meltability may be impaired, i.e., the melting temperature may become too high. B2O3 can be used to lower the melting temperature, but high levels of B2O3 impair the annealing point.

[0047] In addition to considerations of meltability and annealing point, for AMLCD applications, the CTE of the glass should match that of the silicon. To achieve such a CTE value, the example glass controls the RO content of the glass. Controlling the RO content for a given Al2O3 content corresponds to controlling the RO / Al2O3 ratio. In practice, if the RO / Al2O3 ratio is less than approximately 1.38, glass with a suitable CTE can be manufactured.

[0048] In addition to these considerations, these glasses may be moldable by down-draw methods, such as fusion. This means that the liquid-phase viscosity of the glass needs to be relatively high. Individual alkaline earth elements play an important role in this regard, as they can destabilize the crystalline phases that would otherwise form. BaO and SrO are particularly effective in controlling the liquid-phase viscosity and are included in the example glasses at least for this purpose. As shown in the examples presented below, various combinations of alkaline earth elements produce glasses with high liquid-phase viscosity, and the sum of these alkaline earth elements satisfies the constraints of a low melting temperature, a high annealing point, and the RO / Al2O3 ratio required to achieve a suitable CTE.

[0049] In addition to the components described herein, the glass compositions described herein may contain various other oxides to modulate the various physical, melting, clarification, and molding properties of the glass. Examples of such other oxides include, but are not limited to, TiO2, MnO, Fe2O3, ZnO, Nb2O5, MoO3, ZrO2, Ta2O5, WO3, Y2O3, La2O3, and CeO2. In one embodiment, the amount of each of these oxides may be 2.0 mole percent or less, and their total concentration may be 4.0 mole percent or less. The glass compositions described herein may also contain various contaminants, particularly Fe2O3 and ZrO2, that are associated with batch materials and / or introduced into the glass by melting, clarification, and / or molding equipment used to manufacture the glass. The glass may also contain SnO2 as a result of Joule melting using a tin oxide electrode, and / or through batch formulations of tin-containing materials, such as SnO2, SnO, SnCO3, SnC2O2, etc.

[0050] The aforementioned glass composition is generally alkali-free; however, the glass may contain some alkaline contaminants. For AMLCD applications, it is desirable to maintain the alkali level below 0.1 mole percent to avoid adverse effects on TFT performance due to the diffusion of alkali ions from the glass into the silicon of the thin-film transistor (TFT). As used herein, “alkali-free glass” is glass having a total alkali concentration of 0.1 mole percent or less, where the total alkali concentration is the sum of the concentrations of Na2O, K2O, and Li2O. In one embodiment, the total alkali concentration is 0.1 mole percent or less.

[0051] As previously mentioned, a (MgO+CaO+SrO+BaO) / Al2O3 ratio of 1 or greater improves clarification, i.e., the removal of gaseous contaminants from the molten batch material. This improvement allows for the use of more environmentally friendly clarification packages. For example, on an oxide basis, the glass compositions described herein may have one or more of the following compositional characteristics: (i) an As2O3 concentration of at most 0.05 mol percent, (ii) an Sb2O3 concentration of at most 0.05 mol percent, and (iii) an SnO2 concentration of at most 0.25 mol percent.

[0052] As2O3 is an effective high-temperature fining agent for AMLCD glass, and in some embodiments described herein, As2O3 is used for fining due to its excellent fining properties. However, As2O3 is toxic and requires special handling during the glass manufacturing process. Therefore, in certain embodiments, fining is performed without using a substantial amount of As2O3, i.e., the finished glass contains at most 0.05 mol percent of As2O3. In one embodiment, As2O3 is intentionally not used for glass fining. In such cases, the finished glass typically contains at most 0.005 mol percent of As2O3 as a result of contaminants present in the batch material and / or the equipment used to melt that batch material.

[0053] Although not as toxic as As2O3, Sb2O3 is also harmful and requires special handling. Furthermore, Sb2O3 increases density, increases CTE, and decreases annealing point compared to glass using As2O3 or SnO2 as a fining agent. Therefore, in certain embodiments, fining is performed without using a substantial amount of Sb2O3, i.e., the finished glass contains at most 0.05 mole percent of Sb2O3. In other embodiments, Sb2O3 is intentionally not used for glass fining. In such cases, the finished glass typically contains at most 0.005 mole percent of Sb2O3 as a result of contaminants present in the batch material and / or the equipment used to melt that batch material.

[0054] While fining with tin (i.e., SnO2) is generally less effective than fining with As2O3 and Sb2O3, SnO2 is a common material with no known harmful properties. Furthermore, for many years, SnO2 has been a component of AMLCD glass due to the use of tin oxide electrodes in the Joule melting of batch materials for such glass. The presence of SnO2 in AMLCD glass has not resulted in any known adverse effects on the use of these glasses in the manufacture of liquid crystal displays. However, high concentrations of SnO2 are undesirable because they can cause crystal defects in AMLCD glass. In one embodiment, the concentration of SnO2 in the finished glass is 0.25 mole percent or less.

[0055] Tin clarification may be used alone or, if desired, in combination with other clarification techniques. For example, tin clarification can be combined with halide clarification, such as bromine clarification. Other possible combinations include, but are not limited to, tin clarification in addition to sulfate, sulfide, cerium oxide, mechanical foaming, and / or vacuum clarification. These other clarification techniques may be used alone. In certain embodiments, the clarification process can be made easier and more effective by maintaining the (MgO+CaO+SrO+BaO) / Al2O3 ratio and the concentrations of individual alkaline earth elements within the ranges described above.

[0056] The glass described herein can be manufactured using various techniques known in the art. In one embodiment, these glasses are manufactured using a down-draw method, such as the fusion down-draw method. In one embodiment, an alkali-free glass sheet is manufactured, comprising the steps of selecting, melting, and clarifying batch material such that the glass constituting the sheet contains SiO2, Al2O3, B2O3, MgO, CaO, and BaO, and has, on an oxide basis, (i) a (MgO+CaO+SrO+BaO) / Al2O3 ratio of 1 or more; (ii) an MgO content of 2.5 mole percent or more; (iii) a CaO content of 2.7 mole percent or more; and (iv) an (SrO+BaO) content of 1 mole percent or more. A method for producing alkali-free glass sheets by a down-draw method is described, wherein (a) the clarification step is carried out without using a substantial amount of arsenic (and, if necessary, without using a substantial amount of antimony), and (b) a population of 50 continuous glass sheets produced by the down-draw method from a molten and clarified batch material has an average gaseous content level of less than 0.10 gaseous content / cubic centimeter, and each sheet in the population has a volume of at least 500 cubic centimeters.

[0057] U.S. Patent No. 5,785,726 (Dorfeld et al.), No. 6,128,924 (Bange et al.), No. 5,824,127 (Bange et al.), and concurrently pending patent application No. 11 / 116669 disclose processes for producing arsenic-free glass. U.S. Patent No. 7,696,113 (Ellison) discloses a process for producing arsenic and antimony-free glass using iron and tin to minimize gaseous inclusions. All of U.S. Patents No. 5,785,726, No. 6,128,924, No. 5,824,127, concurrently pending patent application No. 11 / 116669, and U.S. Patent No. 7,696,113 are incorporated herein by reference.

[0058] In one embodiment, a population of 50 continuous glass sheets produced by a down-draw method from a molten and clarified batch material has an average gaseous content of less than 0.05 gaseous content / cubic centimeter, and each sheet in the population has a volume of at least 500 cubic centimeters.

[0059] In some embodiments, the exemplary glass has a viscosity curve and high liquid-phase viscosity that meets a specific threshold of customer-facing attributes and has the composition range shown in Table 1 below, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0060] [Table 1]

[0061] In some embodiments, the exemplary glass has a viscosity curve and high liquid-phase viscosity that meets a specific threshold of customer-facing attributes and has the composition range shown in Table 2 below, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0062] [Table 2]

[0063] In some embodiments, the exemplary glass has a viscosity curve and high liquid-phase viscosity that meets a specific threshold of customer-facing attributes and has the composition range shown in Table 3 below, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0064] [Table 3]

[0065] In some embodiments, the exemplary glass has a viscosity curve and high liquid-phase viscosity that meets a specific threshold of customer-facing attributes and has the composition range shown in Table 4 below, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percent of their respective oxide components.

[0066] [Table 4]

[0067] In some embodiments, some exemplary glass embodiments can be described by a convex hull, which corresponds to the smallest convex boundary containing a series of points within a space of a given size. Considering a space created by any of the compositions included in Tables 1, 2, 3, and 4, we can consider SiO2 as one group, Al2O3 and B2O3 as a group named Al2O3_B2O3, and the remaining components as a group named RO, containing MgO, CaO, SrO, BaO, SnO2, and other oxides listed in their respective ranges, and define the respective convex hulls for these compositions. For example, a ternary space has a boundary set by the compositions in Table 1 in mole percent and can be defined by the space shown in Figure 3. Table 5 below provides compositions (mol percent) that define the boundaries of the convex hulls for the composition ranges defined in Table 1.

[0068] [Table 5]

[0069] In further embodiments, the exemplary glass can be described by a convex hull defined by the space created in Table 2 above, for the remaining components, which are considered to be the group named RO, containing SiO2, Al2O3_B2O3, and MgO, CaO, SrO, BaO, SnO2, and other oxides listed in their respective ranges. Next, the ternary space can be defined by the space shown in Figure 4, with its boundaries set by the compositions in Table 2 in mole percent. Table 6 below provides compositions (mol percent) that define the boundaries of the convex hull for the ranges defined in Table 2.

[0070] [Table 6]

[0071] In additional embodiments, the exemplary glass can be described by a convex hull defined by the space created in Table 3 above, for the remaining components, which are considered to be the group named RO, containing SiO2, Al2O3_B2O3, and MgO, CaO, SrO, BaO, SnO2, and other oxides listed in their respective ranges. The ternary space can then be defined by the space shown in Figure 5, with its boundaries set by the compositions in Table 3 in mole percent. Table 7 below provides the compositions (mol percent) that define the boundaries of the convex hull for the ranges defined in Table 3.

[0072] [Table 7]

[0073] In some embodiments, the exemplary glass can be described by a convex hull defined by the space created in Table 4 above, for the remaining components, which are considered to be the group named SiO2, Al2O3_B2O3, and the group named RO, which includes MgO, CaO, SrO, BaO, SnO2, and other oxides listed in their respective ranges. Next, the ternary space can be defined by the space shown in Figure 6, with its boundaries set by the compositions in Table 4 in mole percent. Table 8 below provides the compositions (mol percent) that define the boundaries of the convex hull for the ranges defined in Table 4.

[0074] [Table 8]

[0075] Next, with respect to the attributes of such exemplary compositions, formulas can be derived. For example, Formula 1 below provides a suitable range of exemplary glasses, expressed in mole percent, having viscosity curves and high liquid-phase viscosity that satisfy specific thresholds of customer-facing attributes such as Young's modulus: 70 GPa ≤ 549.899 - 4.811 * SiO2-4.023 * Al2O3-5.651 * B2O3-4.004 * MgO-4.453 * CaO-4.753 * SrO-5.041 * BaO ≤ 90 GPa (1)

[0076] Figure 7 is a graphical representation of equation (1) for 20,000 randomly selected compositions within the convex hull of Figure 3, enclosed by the compositional boundaries shown in Table 5.

[0077] Further non-limiting examples include Equation 2 below, which provides a suitable range of exemplary glasses, expressed in mole percent, having viscosity curves and high liquid-phase viscosity that satisfy specific thresholds of customer-facing attributes such as annealing point: 720℃≦1464.862-6.339 * SiO2-1.286 * Al2O3-17.284 * B2O3-12.216 * MgO-11.448 * CaO-11.367 * SrO-12.832 * BaO ≤ 810℃ (2)

[0078] Figure 8 is a graphical representation of equation (2) for 20,000 randomly selected compositions within the convex hull of Figure 3, enclosed by the compositional boundaries shown in Table 5.

[0079] Of course, such examples would allow a person skilled in the art to define additional compositional components of the exemplary glass as a function of attributes that face further customers, and therefore the scope of the accompanying claims should not be limited hereby.

[0080] Some embodiments provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 66–70.5% SiO2, 11.2–13.3% Al2O3, 2.5–6% B2O3, 2.5–6.3% MgO, 2.7–8.3% CaO, 1–5.8% SrO, and 0–3% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of the oxide components. Further embodiments include an RO / Al2O3 ratio of 0.98 ≤ (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.38 or an MgO / RO ratio of 0.18 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.45. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical clarifier. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical clarifier. Some embodiments may have a slow-cooling point above 750°C, above 765°C, or above 770°C. Some embodiments may have a liquid-phase viscosity above 100,000 poise, above 150,000 poise, or above 180,000 poise. Some embodiments may have a Young's modulus above 80 GPa, above 81 GPa, or above 81.5 GPa. Some embodiments may have a density of less than 2.55 g / cc, less than 2.54 g / cc, or less than 2.53 g / cc. Some embodiments may have a T200P of less than 1665°C, less than 1650°C, or less than 1640°C. Some embodiments may have a T35kP of less than 1280°C, less than 1270°C, or less than 1266°C. Some embodiments may have a T200P-T(ann) of less than 890°C, less than 880°C, less than 870°C, or less than 865°C. Some embodiments may have a T200P-T(ann) of less than 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise.Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof account for less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. The exemplary objects made from these glass materials can be manufactured by down-draw sheet manufacturing, fusion, or variations thereof.

[0081] Some embodiments provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 68–79.5% SiO2, 12.2–13% Al2O3, 3.5–4.8% B2O3, 3.7–5.3% MgO, 4.7–7.3% CaO, 1.5–4.4% SrO, and 0–2% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.2 or an MgO / RO ratio of 0.24 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.36. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent. Some embodiments may have a T200P-T(ann) below 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise. Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, a T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 constitute less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method or a fusion method or a variation thereof.

[0082] Some embodiments provide a substantially alkali-free glass containing, in mole percent on an oxide basis, 68.3–69.5% SiO2, 12.4–13% Al2O3, 3.7–4.5% B2O3, 4–4.9% MgO, 5.2–6.8% CaO, 2.5–4.2% SrO, and 0–1% BaO, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.09 ≤ (MgO+CaO+SrO+BaO) / Al2O3 ≤ 1.16 or an MgO / RO ratio of 0.25 ≤ MgO / (MgO+CaO+SrO+BaO) ≤ 0.35. Some embodiments may also contain 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent. Some embodiments may also contain 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent. Some embodiments may have a T200P-T(ann) below 890°C, T(ann) ≥ 750°C, a Young's modulus greater than 80 GPa, a density less than 2.55 g / cc, and a liquid-phase viscosity greater than 100,000 Poise. Some embodiments may have a T200P-T(ann) below 880°C, T(ann) ≥ 765°C, a Young's modulus greater than 81 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 150,000 Poise. Some embodiments may have a T200P-T(ann) below 865°C, a T(ann) ≥ 770°C, a Young's modulus greater than 81.5 GPa, a density less than 2.54 g / cc, and a liquid-phase viscosity greater than 180,000 Poise. In some embodiments, As2O3 and Sb2O3 constitute less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than about 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method or a fusion method or a variation thereof.

[0083] In some embodiments, the relation is: 70GPa ≤ 549.899 - 4.811 * SiO2-4.023 * Al2O3-5.651 * B2O3-4.004 * MgO-4.453 * CaO-4.753 * SrO-5.041 * The present invention provides a glass having a Young's modulus in the range defined by BaO ≤ 90 GPa, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the molar percentage of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2. Some embodiments may also contain 0.01 to 0.4 mol% of SnO2, As2O3, or Sb2O3, F, Cl, or Br as chemical fining agents. Some embodiments may also contain 0.005 to 0.2 mol% of Fe2O3, CeO2, or MnO2 as chemical fining agents. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than approximately 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method, a fusion method or a variation thereof.

[0084] In some embodiments, the relation is: 720℃≦1464.862-6.339 * SiO2-1.286 * Al2O3-17.284 * B2O3-12.216 * MgO-11.448 * CaO-11.367 * SrO-12.832 *The provided glass has an annealing point in the range defined by BaO ≤ 810°C, where SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the molar percentages of oxide components. Further embodiments include an RO / Al2O3 ratio of 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2. Some embodiments may also contain 0.01 to 0.4 mol% of SnO2, As2O3, or Sb2O3, F, Cl, or Br as chemical fining agents. Some embodiments may also contain 0.005 to 0.2 mol% of Fe2O3, CeO2, or MnO2 as chemical fining agents. In some embodiments, As2O3 and Sb2O3 account for less than about 0.005 mol%. In some embodiments, Li2O, Na2O, K2O, or a combination thereof constitute less than approximately 0.1 mol% of the glass. In some embodiments, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used. Exemplary objects made from these glasses can be manufactured by a down-draw sheet manufacturing method, a fusion method or a variation thereof.

[0085] It will be recognized that various embodiments of the disclosure will include certain characteristics, elements, or processes described in relation to that particular embodiment. It will also be recognized that certain characteristics, elements, or processes described in relation to one particular embodiment may be replaced or combined with alternative embodiments in various not-illustrated combinations or sequences.

[0086] As used here, it should be understood that nouns refer to "at least one" object and should not be limited to "only one" object unless explicitly indicated otherwise.

[0087] A range can be expressed here as "approximately" from one specific value and / or "approximately" to another specific value. When a range is expressed in this way, the example includes that one specific value and / or the other specific value. Similarly, when a value is expressed as an approximation using the antecedent "approximately," it will be understood that the specific value forms another aspect. It will be further understood that each endpoint of those ranges is significant both with respect to the other endpoint and independently of the other endpoint.

[0088] The terms “substantial” and “effectively” used herein, and their variations thereof, are intended to indicate that the described characteristic is equal to or approximately equal to a certain value or description.

[0089] Unless otherwise specified, none of the methods described herein are intended to require that the steps be performed in a specific order. Therefore, if a claim for a method does not actually enumerate the order in which the steps should be performed, or if it is not otherwise specifically stated in the claims or description that the steps should be limited to a particular order, no particular order is intended to be implied.

[0090] While various characteristics, elements, or processes of a particular embodiment may be disclosed using the transitional phrase “includes,” it should be understood that alternative embodiments are implied, including those that could be described using the transitional phrase “consist of” or “substantially from.” Therefore, for example, alternative embodiments implied for an apparatus including A+B+C include embodiments in which the apparatus consists of A+B+C, and embodiments in which the apparatus substantially consists of A+B+C.

[0091] It will be apparent to those skilled in the art that various modifications and changes can be made to this disclosure without departing from its spirit and scope. Since modifications, combinations, subordinate combinations and changes of embodiments of the disclosure, including the spirit and substance of this disclosure, will be conceivable to those skilled in the art, this disclosure should be construed as encompassing all of the accompanying claims and their equivalents. [Examples]

[0092] The following examples are described below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to include all embodiments of the means disclosed herein, but are intended to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the disclosure that would be obvious to those skilled in the art.

[0093] Efforts have been made to ensure accuracy regarding numbers (e.g., quantity, temperature), but a certain degree of error and deviation should be considered. Unless otherwise specified, temperature is expressed in °C or ambient temperature, and pressure is atmospheric pressure or close to it. The composition itself is given in mole percent on an oxide basis and normalized to 100%. There are many reaction conditions, such as component concentrations, temperature, pressure, and other reaction ranges and condition variations and combinations that can be used to optimize the purity and yield of the product obtained from the described process. Only reasonable and routine experiments are required to optimize such process conditions.

[0094] The glass properties listed in this table were determined according to standard techniques in the field of glass technology. Therefore, the coefficient of linear thermal expansion (CTE) over the temperature range of 25-300°C is ×10 -7 The values ​​are expressed in / °C, and the annealing point is expressed in °C. These were determined by fiber stretching techniques (ASTM standards E228-85 and C336, respectively). grams / cm 3The density expressed was measured by the Archimedes method (ASTM C693). The melting temperature expressed in °C (defined as the temperature at which the glass molten material exhibits a viscosity of 200 poise) was calculated using the fitting of Fulcher's equation to high-temperature viscosity data measured by a cylindrical rotational viscometer (ASTM C965-81).

[0095] The liquidus temperature of the glass, expressed in °C, was measured using the isothermal liquidus method. This method involves placing crushed glass particles into a small platinum crucible, placing the crucible in a furnace with strictly controlled temperature, and heating the crucible at the temperature of interest for 24 hours. After heating, the crucible is air-cooled, and microscopic examination is used to determine the crystalline phases present and the percentage of crystallinity within the glass. More specifically, a glass sample is taken from the Pt crucible in one piece and examined using a polarizing microscope to identify the location and nature of crystals formed at the Pt-air interface and within the sample. The sample is subjected to this process at a number of temperatures intended to surround the actual liquidus temperature of the glass. Once the crystalline phases and percentages of crystallinity have been identified at various temperatures, these temperatures can be used to determine the zero crystallinity temperature, or liquidus temperature, of the composition of interest. The tests are sometimes conducted for longer periods (e.g., 72 hours) to observe slower growth stages. The crystalline phases for the various glasses in Table 9 are indicated by the following abbreviations: anor -- anorthite, calcium aluminosilicate mineral; cris -- cristobalite (SiO2); cels -- mixed alkaline earth celsian; Sr / Alsil -- strontium aluminosilicate phase; SrSi -- strontium silicate phase. The liquid-phase viscosity, expressed in Poise, was determined from the liquid-phase temperature and the coefficients of Fulcher's equation.

[0096] The Young's modulus values, expressed in GPa, were determined using the general type of resonant ultrasonic spectroscopy technique described in ASTM E1875-00e1.

[0097] Examples of glass are given in Table 9. As can be seen from Table 9, the example glass may have density, CTE, annealing point, and Young's modulus values ​​that make it suitable for AMLCD substrate applications, more specifically, display applications such as low-temperature polysilicon and oxide thin-film transistor applications. Although not shown in this table, the glass has similar durability in acidic and basic media as that obtained from commercially available AMLCD substrates, and is therefore suitable for AMLCD applications. The example glass can be formed using down-draw techniques and, in particular, conforms to the fusion method according to the criteria described above.

[0098] The example glass in the table was prepared using commercially available sand as the silica source, ground so that 90% by mass passed through a standard US 100-mesh sieve. Alumina was the alumina source, periclase was the MgO source, limestone was the CaO source, strontium carbonate, strontium nitrate, or a mixture thereof was the SrO source, barium carbonate was the BaO source, and tin(IV) oxide was the SnO2 source. The raw materials were thoroughly mixed and loaded into a platinum container suspended in a furnace heated with a silicon carbide grover, melted and stirred for several hours at a temperature between 1600°C and 1650°C to ensure homogeneity, and delivered through an orifice at the bottom of the platinum container. The resulting glass putty was slowly cooled at or near its annealing point, and then subjected to various experimental methods to determine its physical, viscous, and liquidus properties.

[0099] The glasses in this table can be prepared using standard methods well known to those skilled in the art. Such methods include continuous melting processes, such as those carried out in a continuous melting process, in which the melting apparatus used is heated by gas, electricity, or a combination thereof.

[0100] Suitable raw materials for manufacturing the example glass include commercially available sand as a source of SiO2; alumina, aluminum hydroxide, hydrated forms of alumina, and various aluminosilicates, nitrates, and halides as sources of Al2O3; boric acid, boric anhydride, and boron oxide as sources of B2O3; periclase, dolomite (which is also a source of CaO), magnesia, magnesium carbonate, magnesium hydroxide, and various forms of magnesium silicate, aluminosilicates, nitrates, and halides as sources of MgO; limestone, aragonite, dolomite (which is also a source of MgO), wollastonite, and various forms of calcium silicate, aluminosilicates, nitrates, and halides as sources of CaO; and oxides, carbonates, nitrates, and halides of strontium and barium. If a chemical clarifier is desired, tin may be added as SnO2, as a mixed oxide with another major glass component (e.g., CaSnO3), or under oxidizing conditions as SnO, tin oxalate, tin halide, or other compounds of tin known to those skilled in the art.

[0101] The glass in this table contains SnO2 as a fining agent, but other chemical fining agents may also be used to obtain glass of sufficient quality for TFT substrate applications. For example, the example glass may use one or a combination of As2O3, Sb2O3, CeO2, Fe2O3, and halides as careful additives to promote fining, and any of these may be used together with the SnO2 chemical fining agent shown in the examples. Of these, As2O3 and Sb2O3 are generally recognized as hazardous materials and are subject to waste flow regulations, such as those generated during the glass manufacturing process or the processing of TFT panels. Therefore, it is desirable to limit the concentrations of As2O3 and Sb2O3, individually or in combination, to 0.005 mole percent or less.

[0102] In addition to the elements carefully included in the example glass, almost all stable elements in the periodic table are present in the glass at some level, either through low levels of contamination in the raw materials, high-temperature corrosion of refractories and precious metals during the manufacturing process, or careful introduction at low levels to fine-tune the properties of the final glass. For example, zirconium may be introduced as a contaminant through interaction with zirconium-rich refractories. Further examples include platinum and rhodium, which may be introduced through interaction with precious metals. Further examples include iron, which may be introduced as an inclusion in the raw materials or carefully added to improve control of gaseous inclusions. Further examples include manganese, which may be introduced to control color or to improve control of gaseous inclusions. Further examples include alkalis, which may be present as inclusions at levels up to approximately 0.1 mole percent in total concentration of Li₂O, Na₂O, and K₂O.

[0103] Hydrogen is a hydroxyl anion (OH). - It is inevitably present in this form, and its presence can be confirmed by standard infrared spectroscopy techniques. Dissolved hydroxyl ions significantly and nonlinearly affect the annealing point of the example glass, and therefore, in order to obtain the desired annealing point, it will be necessary to adjust the concentration of the major oxide component to compensate. The hydroxyl ion concentration can be controlled to some extent by the selection of raw materials or melting system. For example, boric acid is a major source of hydroxyl, and replacing boric acid with boron oxide may be a useful means of controlling the hydroxyl concentration in the final glass. The same reasoning applies to other potential raw materials containing hydroxyl ions, hydrates, or compounds containing physically or chemically adsorbed water molecules. If a burner is used in the melting process, hydroxyl ions may also be introduced by combustion products from the combustion of natural gas and associated hydrocarbons, and therefore, in order to compensate, it would be desirable to shift the energy used for melting from the burner to the electrodes. Alternatively, an iterative process to adjust the major oxide component may be used instead to compensate for the harmful effects of dissolved hydroxyl ions.

[0104] Sulfur is frequently present in natural gas and is also a contaminant in the raw materials of many carbonates, nitrates, halides, and oxides. Sulfur, in the form of SO2, can be a troublesome source of gaseous inclusions. The tendency to form SO2-rich defects can be controlled to a significant extent by controlling the sulfur levels in the raw materials and by including low levels of relatively reduced polyvalent cations in the glass matrix. While not intended to be theoretical, SO2-rich gaseous inclusions can lead to dissolved sulfate groups (SO4) in the glass. = This appears to be mainly caused by the reduction of ). The elevated barium concentration in the example glass appears to increase the desulfurization effect in the glass in the early stages of melting, but as mentioned above, barium is required to obtain a low liquidus temperature, and therefore a high liquidus viscosity. Carefully controlling the sulfur level in the raw materials to a low level is a useful means of reducing dissolved sulfur (probably as sulfate) in the glass. Specifically, sulfur may be less than 200 ppm by mass in the batch material, or less than 100 ppm by mass in the batch material.

[0105] To control the tendency of the example glass to form SO2 blisters, reduced polyvalent elements may be used. While not intended to be theoretically restrictive, these elements act as potential electron donors that suppress the electromotive force for sulfate reduction. The reduction of sulfate groups is, SO4 = →SO2+O2+2e - Half-reactions such as the above can be described, and in the formula, e - represents electrons. The "equilibrium constant" of this half-reaction is K eq =[SO2][O2][e - ] 2 / [SO4 = ] In the formula, square brackets indicate chemical activity. Ideally, the reaction produces SO2, O2, and e -We want to create sulfate groups from it. Adding nitrates, peroxides, or other oxygen-rich raw materials may be helpful, but it may work against the reduction of sulfate groups in the initial stages of melting, which would negate the benefit of adding them in the initial stages. SO2 has very low solubility in most glasses and is therefore not practical to add to the glass melting process. Electrons will be "added" by reduced polyvalent elements. For example, ferrous iron (Fe 2+ The appropriate electron-donating half-reaction for ) is 2Fe 2+ →2Fe 3+ +2e - This is expressed as follows. This "activity" of the electron forces the sulfate reduction reaction to the left, and SO4 in the glass. = It can stabilize the following, but is not limited to Fe. 2+ Mn 2+ Sn 2+ Sb 3+ As 3+ , V 3+ Ti 3+ , and others familiar to those skilled in the art. In each case, it would be important to minimize the concentration of such components in order to avoid harmful effects on the color of the glass, or, in the case of As and Sb, to avoid adding such components at high or sufficient levels in order to minimize the complexity of waste management in the end-user's process.

[0106] In addition to the main oxide components of the example glass and the trace or impurities mentioned above, halides may be present at various levels, either as contaminants introduced by the selection of raw materials or as intentional components used to eliminate gaseous inclusions in the glass. Halides may be included as clarifiers at levels of about 0.4 mol percent or less, but it is generally desirable to use even smaller amounts to avoid corrosion of exhaust gas handling equipment. In some embodiments, the concentration of individual halide elements is less than about 200 ppm by mass for each individual halide, or less than about 800 ppm by mass for the sum of all halide elements.

[0107] In addition to these major oxide components, trace and impurities, polyvalent elements, and halide clarifying agents, it may be useful to include low concentrations of other colorless oxide components to achieve desired physical, optical, or viscoelastic properties. Examples of such oxides include, but are not limited to, TiO2, ZrO2, HfO2, Nb2O5, Ta2O5, MoO3, WO3, ZnO, In2O3, Ga2O3, Bi2O3, GeO2, PbO, SeO3, TeO2, Y2O3, La2O3, Gd2O3, and other compounds known to those skilled in the art. By iterative processes adjusting the relative ratios of the major oxide components of the exemplary glass, such colorless oxides can be added up to levels of about 2 mole percent without unacceptable effects on the annealing point or liquid-phase viscosity.

[0108] Table 9 shows illustrative glass according to some embodiments of the present disclosure.

[0109] [Table 9-1]

[0110] [Table 9-2]

[0111] Table 9-3

[0112] Table 9-4

[0113] Table 9-5

[0114] Table 9-6

[0115] Table 9-7

[0116] Table 9-8

[0117] Table 9-9

[0118] Table 9-10

[0119] Table 9-11

[0120] Table 9-12

[0121] Table 9-13

[0122] [Table 9-14]

[0123] [Table 9-15]

[0124] [Table 9-16]

[0125] [Table 9-17]

[0126] [Table 9-18]

[0127] [Table 9-19]

[0128] [Table 9-20]

[0129] Preferred embodiments of the present invention are described below in separate sections.

[0130] Embodiment 1 A substantially alkali-free glass containing, in mole percent on an oxide basis, 66-70.5% SiO2, 11.2-13.3% Al2O3, 2.5-6% B2O3, 2.5-6.3% MgO, 2.7-8.3% CaO, 1-5.8% SrO, and 0-3% BaO.

[0131] Embodiment 2 The glass according to Embodiment 1, wherein 0.98 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.38.

[0132] Embodiment 3 The glass according to Embodiment 1, wherein 0.18 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.45.

[0133] Embodiment 4 The glass according to Embodiment 1, containing 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent.

[0134] Embodiment 5 The glass according to Embodiment 1, containing 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent.

[0135] Embodiment 6 The glass according to Embodiment 1, wherein the glass has an annealing point of over 750°C.

[0136] Embodiment 7 The glass according to Embodiment 1, wherein the glass has an annealing point of over 765°C.

[0137] Embodiment 8 The glass according to Embodiment 1, wherein the glass has an annealing point of over 770°C.

[0138] Embodiment 9 The glass according to Embodiment 1, wherein the glass has a liquid phase viscosity of more than 100,000 poise.

[0139] Embodiment 10 The glass according to Embodiment 1, wherein the glass has a liquid phase viscosity of more than 150,000 poise.

[0140] Embodiment 11 The glass according to Embodiment 1, wherein the glass has a liquid phase viscosity of more than 180,000 poise.

[0141] Embodiment 12 The glass according to Embodiment 1, wherein the glass has a Young's modulus of more than 80 GPa.

[0142] Embodiment 13 The glass according to Embodiment 1, wherein the glass has a Young's modulus greater than 81 GPa.

[0143] Embodiment 14 The glass according to Embodiment 1, wherein the glass has a Young's modulus greater than 81.5 GPa.

[0144] Embodiment 15 The glass according to Embodiment 1, wherein the glass has a density of less than 2.55 g / cc.

[0145] Embodiment 16 The glass according to Embodiment 1, wherein the glass has a density of less than 2.54 g / cc.

[0146] Embodiment 17 The glass according to Embodiment 1, wherein the glass has a density of less than 2.53 g / cc.

[0147] Embodiment 18 The glass according to Embodiment 1, wherein the glass has a T200P of less than 1665℃.

[0148] Embodiment 19 The glass according to Embodiment 1, wherein the glass has a T200P of less than 1650℃.

[0149] Embodiment 20 The glass according to Embodiment 1, wherein the glass has a T200P of less than 1640℃.

[0150] Embodiment 21 The glass according to Embodiment 1, wherein the glass has a T35kP of less than 1280℃.

[0151] Embodiment 22 The glass according to Embodiment 1, wherein the glass has a T35kP of less than 1270℃.

[0152] Embodiment 23 The glass according to Embodiment 1, wherein the glass has a T35kP of less than 1266℃.

[0153] Embodiment 24 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 890℃.

[0154] Embodiment 25 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 880℃.

[0155] Embodiment 26 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 870℃.

[0156] Embodiment 27 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 865℃.

[0157] Embodiment 28 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 890°C, a T(ann) of ≥ 750°C, a Young's modulus greater than 80 GPa, a density of less than 2.55 g / cc, and a liquid phase viscosity greater than 100,000 Poise.

[0158] Embodiment 29 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 880℃, a T(ann) ≥ 765℃, a Young's modulus greater than 81 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 150,000 Poise.

[0159] Embodiment 30 The glass according to Embodiment 1, wherein the glass has a T200P-T(ann) of less than 865℃, a T(ann) ≥ 770℃, a Young's modulus greater than 81.5 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 180,000 Poise.

[0160] Embodiment 31 The glass according to Embodiment 1, wherein As2O3 and Sb2O3 account for less than approximately 0.005 mol%.

[0161] Embodiment 32 The glass according to Embodiment 1, wherein Li2O, Na2O, K2O, or a combination thereof, constitutes less than approximately 0.1 mol% of the glass.

[0162] Embodiment 33 A method for producing glass according to Embodiment 1, wherein the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

[0163] Embodiment 34 An object made from glass as described in Embodiment 1, which is manufactured by the down-draw sheet manufacturing method.

[0164] Embodiment 35 An object made from glass as described in Embodiment 1, manufactured by a fusion method or a variation thereof.

[0165] Embodiment 36 A liquid crystal display substrate made from glass as described in Embodiment 1.

[0166] Embodiment 37 A substantially alkali-free glass containing, in mole percent on an oxide basis, 68-79.5% SiO2, 12.2-13% Al2O3, 3.5-4.8% B2O3, 3.7-5.3% MgO, 4.7-7.3% CaO, 1.5-4.4% SrO, and 0-2% BaO.

[0167] Embodiment 38 The glass according to Embodiment 37, wherein 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2.

[0168] Embodiment 39 The glass according to Embodiment 37, wherein 0.24 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.36.

[0169] Embodiment 40 The glass according to Embodiment 37, containing 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent.

[0170] Embodiment 41 The glass according to Embodiment 37, containing 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical clarifier.

[0171] Embodiment 42 The glass according to Embodiment 37, wherein the glass has a T200P-T(ann) of less than 890°C, a T(ann) of ≥ 750°C, a Young's modulus greater than 80 GPa, a density of less than 2.55 g / cc, and a liquid phase viscosity greater than 100,000 Poise.

[0172] Embodiment 43 The glass according to Embodiment 37, wherein the glass has a T200P-T(ann) of less than 880℃, a T(ann) ≥ 765℃, a Young's modulus greater than 81 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 150,000 Poise.

[0173] Embodiment 44 The glass according to Embodiment 37, wherein the glass has a T200P-T(ann) of less than 865℃, a T(ann) of ≥ 770℃, a Young's modulus greater than 81.5 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 180,000 Poise.

[0174] Embodiment 45 The glass according to Embodiment 37, wherein As2O3 and Sb2O3 account for less than approximately 0.005 mol%.

[0175] Embodiment 46 The glass according to Embodiment 37, wherein Li2O, Na2O, K2O, or a combination thereof, constitutes less than approximately 0.1 mol% of the glass.

[0176] Embodiment 47 A method for producing glass according to Embodiment 37, wherein the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

[0177] Embodiment 48 An object made from glass as described in Embodiment 37, which is manufactured by a down-draw sheet manufacturing method.

[0178] Embodiment 49 An object made from glass according to Embodiment 37, which is manufactured by a fusion method or a variation thereof.

[0179] Embodiment 50 A liquid crystal display substrate made from glass as described in Embodiment 37.

[0180] Embodiment 51 A substantially alkali-free glass containing 68.3-69.5% SiO2, 12.4-13% Al2O3, 3.7-4.5% B2O3, 4-4.9% MgO, 5.2-6.8% CaO, 2.5-4.2% SrO, and 0-1% BaO, expressed in mole percent on an oxide basis, wherein SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of oxide components.

[0181] Embodiment 52 The glass according to Embodiment 51, wherein 1.09 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.16.

[0182] Embodiment 53 The glass according to Embodiment 51, wherein 0.25 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.35.

[0183] Embodiment 54 The glass according to Embodiment 51, containing 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent.

[0184] Embodiment 55 The glass according to Embodiment 51, containing 0.005 to 0.2 mol% of one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent.

[0185] Embodiment 56 The glass according to Embodiment 51, wherein the glass has a T200P-T(ann) of less than 890°C, a T(ann) of ≥ 750°C, a Young's modulus greater than 80 GPa, a density of less than 2.55 g / cc, and a liquid phase viscosity greater than 100,000 Poise.

[0186] Embodiment 57 The glass according to Embodiment 51, wherein the glass has a T200P-T(ann) of less than 880℃, a T(ann) ≥ 765℃, a Young's modulus greater than 81 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 150,000 Poise.

[0187] Embodiment 58 The glass according to Embodiment 51, wherein the glass has a T200P-T(ann) of less than 865℃, a T(ann) of ≥ 770℃, a Young's modulus greater than 81.5 GPa, a density of less than 2.54 g / cc, and a liquid phase viscosity greater than 180,000 Poise.

[0188] Embodiment 59 The glass according to Embodiment 51, wherein As2O3 and Sb2O3 account for less than approximately 0.005 mol%.

[0189] Embodiment 60 The glass according to embodiment 51, wherein Li2O, Na2O, K2O, or a combination thereof accounts for less than about 0.1 mol% of the glass.

[0190] Embodiment 61 A method for manufacturing the glass according to embodiment 51, wherein the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

[0191] Embodiment 62 An object made from the glass according to embodiment 51, which is manufactured by the down-draw sheet manufacturing method.

[0192] Embodiment 63 An object made from the glass according to embodiment 51, which is manufactured by the fusion method or a variant thereof.

[0193] Embodiment 64 A substrate for a liquid crystal display made from the glass according to embodiment 51.

[0194] Embodiment 65 Relationship: 70 GPa ≤ 549.899 - 4.811 * SiO2 - 4.023 * Al2O3 - 5.651 * B2O3 - 4.004 * MgO - 4.453 * CaO - 4.753 * SrO - 5.041 * BaO ≤ 90 GPa A glass having a Young's modulus within the range defined by: SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percentages of the oxide components of the glass.

[0195] Embodiment 66 The glass according to embodiment 65, wherein 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2.

[0196] Embodiment 67 The glass according to embodiment 65, containing any one or combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical clarifying agent at 0.01 to 0.4 mol%.

[0197] Embodiment 68 The glass according to embodiment 65, containing any one or combination of Fe2O3, CeO2, or MnO2 as a chemical clarifying agent at 0.005 to 0.2 mol%.

[0198] Embodiment 69 The glass according to embodiment 65, in which As2O3 and Sb2O3 occupy less than about 0.005 mol%.

[0199] Embodiment 70 The glass according to embodiment 65, in which Li2O, Na2O, K2O, or a combination thereof occupies less than about 0.1 mol% of the glass.

[0200] Embodiment 71 In a method for manufacturing the glass according to embodiment 65, the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

[0201] Embodiment 72 An object made of the glass according to embodiment 65 and manufactured by the down-draw sheet manufacturing method.

[0202] Embodiment 73 An object made of the glass according to embodiment 65 and manufactured by the fusion method or a variant thereof.

[0203] Embodiment 74 A substrate for a liquid crystal display made of the glass according to embodiment 65.

[0204] Embodiment 75 Relationship: 720°C ≤ 1464.862 - 6.339 * SiO2 - 1.286 *Al2O3-17.284 * B2O3-12.216 * MgO-11.448 * CaO-11.367 * SrO-12.832 * BaO ≤ 810℃ A glass having an annealing point within the range defined by, wherein SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO represent the mole percent of the oxide components of the glass.

[0205] Embodiment 76 The glass according to Embodiment 75, wherein 1.07 ≤ (MgO + CaO + SrO + BaO) / Al2O3 ≤ 1.2.

[0206] Embodiment 77 The glass according to Embodiment 75, containing 0.01 to 0.4 mol% of one or a combination of SnO2, As2O3, or Sb2O3, F, Cl, or Br as a chemical fining agent.

[0207] Embodiment 78 The glass according to Embodiment 75, containing one or a combination of Fe2O3, CeO2, or MnO2 as a chemical fining agent in an amount of 0.005 to 0.2 mol%.

[0208] Embodiment 79 The glass according to Embodiment 75, wherein As2O3 and Sb2O3 account for less than approximately 0.005 mol%.

[0209] Embodiment 80 The glass according to Embodiment 75, wherein Li2O, Na2O, K2O, or a combination thereof, constitute less than approximately 0.1 mol% of the glass.

[0210] Embodiment 81 A method for producing glass according to Embodiment 75, wherein the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

[0211] Embodiment 82 An object made of the glass described in Embodiment 75, which is manufactured by the down-draw sheet manufacturing method.

[0212] Embodiment 83 An object made of the glass described in Embodiment 75, which is manufactured by the fusion method or a variant thereof.

[0213] Embodiment 84 A substrate for a liquid crystal display made of the glass described in Embodiment 75.

Explanation of Signs

[0214] 1 Inlet 2 Compression end 3 Edge director 4 Bottom 9 Weir wall 10 Base

Claims

1. Expressed as a mole percent on an oxide basis, 67.3 to 70.5 SiO ２ , 12.2-13 Al ２ O ３ , B 2.5-4.9 ２ O ３ It contains 2.5 to 6.3 mg of MgO, 2.7 to 6.25 mg of CaO, 1 to 5.8 mg of SrO, and 0.04 to 1 mg of BaO. SiO ２ and Al ２ O ３ The sum of these is greater than 81.4 in mole percent, and the glass has an annealing point of 774°C or higher. Li ２ O, Na ２ O, and K ２ A glass substantially free of alkali, wherein the total concentration of O is less than 0.1 mol%.

2. 0.98≦(MgO+CaO+SrO+BaO) / Al ２ O ３ The glass according to claim 1, wherein the coefficient is ≤ 1.

38.

3. The glass according to claim 1, wherein 18 ≤ MgO / (MgO + CaO + SrO + BaO) ≤ 0.

45.

4. SnO as a chemical clarifier ２ As ２ O ３ , or Sb ２ O ３ The glass according to claim 1, further comprising 0.01 to 0.4 mol% of one or a combination of F, Cl, or Br.

5. Fe as a chemical clarifier ２ O ３ , CEO ２ , or MnO ２ The glass according to claim 1, further comprising 0.005 to 0.2 mol% of any one or a combination of the above.

6. The glass according to claim 1, wherein the glass has a liquid phase viscosity of more than 100,000 poise.

7. The glass according to claim 1, wherein the glass has a Young's modulus of more than 80 GPa.

8. The glass according to claim 1, wherein the glass has a density of less than 2.55 g / cc.

9. The glass according to claim 1, wherein the glass has a T200P of less than 1665°C.

10. The glass according to claim 1, wherein the glass has a T35kP of less than 1280°C.

11. The glass according to claim 1, wherein the glass has a T200P-T(ann) of less than 890°C.

12. The glass according to claim 1, wherein the glass has a temperature of less than 890°C (T200P-T(ann)), a Young's modulus greater than 80 GPa, a density of less than 2.55 g / cc, and a liquid phase viscosity greater than 100,000 Poise.

13. A method for producing glass according to claim 1, wherein the raw materials contain sulfur between 0 and 200 ppm by mass with respect to each raw material used.

14. A method for manufacturing an object made from glass as described in claim 1 by a down-draw sheet manufacturing method.

15. A method for manufacturing an object made from glass according to claim 1 by a fusion method or a variation thereof.

16. A substrate for a liquid crystal display made from the glass described in claim 1.

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