Alkali-free phosphoborosilicate glass

Cross-reference of related applications

0001This application is filed May 9, 2013, in U.S. Provisional Patent Application No. 61 / 821,426 (which relies on its content and is incorporated herein by reference in its entirety), U.S. Code, Vol. 35, Article 119. Claim the benefits of the priority below.

0002The present disclosure relates to glasses that do not contain alkali metals or oxides thereof. More specifically, the present disclosure relates to non-alkali glass that can be formed by down-draw methods such as slot stretching and melt stretching techniques. More specifically, the present disclosure relates to non-alkali glass that can be formed in a clad layer for a glass laminate.

<p num="0003"> Non-alkali phosphoboroaluminosilicate glass is provided. This glass is the network-forming component SiO₂, B₂O₃And Al₂O₃And P₂O₅Contains at least one of. In some embodiments, the glass has a Young's modulus of less than about 78 GPa and / or about 38 × 10 averaged over a temperature range of about 20 ° C to about 300 ° C.^-7It may have a coefficient of thermal expansion of less than / ° C. The glass may be used as a cover glass for electronic devices or as an outer clad layer for glass laminates.</p><p num="0004"> Therefore, one aspect of the present disclosure is about 50 mol% to about 75 mol% SiO.₂, Over 0 mol% ~ about 20 mol% Al₂O₃, Over 0 mol% ~ about 35 mol% B₂O₃, Over 0 mol% ~ about 20 mol% P₂O₅, MgO up to about 5 mol%, CaO up to about 10 mol%, SrO up to about 5 mol%, Fe up to about 0.5 mol%₂O₃, And ZrO up to about 0.1 mol%₂To provide a glass containing, which is substantially free of alkali metal modifiers.</p><p num="0005"> A second aspect of the present disclosure is SiO.₂, B₂O₃, Al₂O₃, And P₂O₅Is to provide glass containing. This glass is substantially free of alkali metal modifiers and has a Young's modulus of less than about 78 GPa and an average of about 38 × 10 over a temperature range of about 20 ° C to about 300 ° C.^-7Has at least one of the coefficients of thermal expansion below / ° C.</p><p num="0006"> A third aspect of the present disclosure is to provide a glass laminate containing a core glass and a clad glass laminated on the outer surface of the core glass. The clad glass layer is SiO₂, B₂O₃, Al₂O₃, And P₂O₅And substantially free of alkali metal modifiers. Clad glass is about 38 × 10 averaged over a temperature range of about 20 ° C to about 300 ° C.^-7Having a first coefficient of thermal expansion of less than / ° C, the core glass has a second coefficient of thermal expansion that is greater than the first coefficient of thermal expansion, averaged over a temperature range of about 20 ° C to about 300 ° C.</p><p num="0007"> A fourth aspect of the present disclosure is to provide a method for producing glass. This method is SiO₂And B₂O₃And Al₂O₃And P₂O₅The present invention comprises a step of providing a glass melt containing at least one of the above and substantially free of an alkali metal modifier, and a step of down-drawing the glass melt to form glass.</p><p num="0008"> These and other aspects, advantages, and salient features will be apparent from the detailed description below, the accompanying drawings, and the attached claims.</p>

0009<figref num="1">It is sectional drawing of the glass laminated body.</figref>

0010In the following description, the same reference numerals refer to the same or corresponding parts throughout some of the figures shown in the drawings. It is also understood that terms such as "upper", "lower", "external", "internal" are expedient terms and should not be construed as restrictive terms unless otherwise noted. I want to. In addition, whenever a group is described as containing a group of elements and at least one of their combinations, the group may include any number of those elements enumerated, either individually or in combination with each other. It should be understood that it may consist of, or may consist of, in essence. Similarly, whenever a group is described as consisting of a group of elements or at least one of their combinations, the groups are either individually or in combination with each other, from any number of those enumerated elements. Please understand that it is okay to become. Unless otherwise noted, the range of values, when enumerated, includes both the upper and lower limits of the range and any range in between. As used herein, a noun refers to "at least one" or "one or more" unless otherwise stated. It should also be understood that the various features disclosed herein and in the drawings may be used in any and all combinations.

0011As used herein, the terms "glass article" and "glass article" are used in their broadest sense to include any object made entirely or partially from glass. Unless otherwise noted, all compositions are expressed in mole percent (mol%) and have a coefficient of thermal expansion (CTE) of 10.^-7Expressed using / ° C.

0012The terms "substantially" and "about" may be used herein to represent inherent uncertainty that may be attributed to any quantitative comparison, value, measurement, or other expression. Please note that. Also, these terms are used herein to describe the extent to which the quantitative representation may vary from the criteria described without changing the basic function of the disputed matter in question.

0013It is understood that the illustrations in general and with reference to FIG. 1 in particular are intended to illustrate a particular embodiment and are not intended to limit the scope of this disclosure or attachment to it. Let's go. Drawings are not necessarily to scale, and certain features and drawings of a drawing may be shown with extreme emphasis at scale or outlined for the purpose of clarity and brevity.

0014Network formation component SiO₂, Al₂O₃, B₂O₃, And P₂O₅Includes, contains no alkali metals and alkali metal oxides, and is low (ie, about 40 × 10 when measured over a temperature range of about 20 ° C to about 300 ° C.^-7Glasses with a coefficient of thermal expansion (CTE) (less than / ° C) and glass articles made from them are described herein. In addition, the amount of alkaline earth oxides is also minimized to further reduce the coefficient of thermal expansion of the glass. In some embodiments, these glasses also have low Young's modulus and shear modulus that improve the inherent or inherent damage resistance of the glass.

0015In some embodiments, the glass described herein can be formed by downdraw methods known in the art, such as slot stretching and melt stretching methods. The melt stretching method is an industrial technique used for large-scale production of thin glass plates. Compared to other flat glass manufacturing techniques such as the float or slot stretching method, the melt stretching method results in a thin glass plate with excellent flatness and surface quality. As a result, the melt-stretching method has become a leading manufacturing technique in the manufacture of thin glass substrates for liquid crystal displays and cover glasses for personal electronic devices such as notebooks, entertainment equipment, tables and laptops.

0016The melt-stretching method requires the flow of molten glass on a trough known as an "isopipe", typically made from zircon or another refractory material. The molten glass overflows from both sides from the top of the isopipe and meets at the bottom of the isopipe to form a veneer, where only the inside of the final plate is in direct contact with the isopipe. Since neither of the exposed surfaces of the final glass plate is in contact with the isopipe material during the stretching process, both outer surfaces of the glass are as good as new and do not require subsequent finishing.

0017To be melt stretchable, the glass must have a sufficiently high liquidus viscosity (ie, the viscosity of the molten glass at the liquidus temperature). In some embodiments, the glasses described herein have a liquidus viscosity of at least about 150 kilopoise. In some embodiments, these glasses have a liquidus viscosity of at least about 300 kpoise.

0018Conventional melt stretching is performed using a single isopipe, resulting in a homogeneous glass product. A more complex laminating and melting method uses two isopipes to form a laminate containing a core glass composition in which either side (or both sides) is surrounded by an outer clad layer. One of the main advantages of laminated melting is that when the coefficient of thermal expansion of the clad glass is smaller than the coefficient of thermal expansion of the core glass, the difference in the coefficient of thermal expansion causes compressive stress in the outer clad layer. This compressive stress increases the strength of the final glassware without the need for ion exchange treatment. Unlike ion exchange, this enhancement can be achieved without the use of alkaline ions in the glass.

0019Therefore, in some embodiments, the non-alkali glass described herein may be used to form the glass laminate illustrated in FIG. The glass laminate 100 includes a clad glass 120 formed from the non-alkali glass described herein or a core glass 110 surrounded by a "clad layer". The core glass 110 has a coefficient of thermal expansion larger than the coefficient of thermal expansion of the non-alkali glass in the clad layer 120. The core glass may be an alkaline aluminosilicate glass in some embodiments. In one non-limiting example, the core glass is a SiO with a composition of 66.9 mol%.₂, 10.1 mol% Al₂O₃, 0.58 mol% B₂O₃, 7.45 mol% Na₂O, 8.39 mol% K₂O, 5.78 mol% MgO, 0.58 mol% CaO, 0.2 mol% SnO₂, 0.01 mol% ZrO₂, And 0.01 mol% Fe₂O₃Alkaline aluminosilicate glass with 572 ° C strain point, 629 ° C annealing point, 888 ° C softening point, and coefficient of thermal expansion = 95.5 × 10.^-7Has / ° C.

0020When used as clad glass in laminates, the non-alkali glass compositions described herein can provide high compressive stress to the clad layer. The coefficient of thermal expansion of melt-moldable non-alkali glass is generally 30 x 10^-7The range is less than / ° C. Such glass is, for example, 90 x 10^-7When combined with alkaline aluminosilicate glass with a coefficient of thermal expansion of / ° C (eg, Gorilla® glass manufactured by Corning Incorporated), the expected compressive stress in the clad glass is that of the elastic stress shown below. It can be calculated using the formulas (subscripts 1 and 2 refer to core glass and clad glass, respectively).

0021<maths num="1"><img id="000003" he="15" wi="114" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></maths>

0022and

0023<maths num="2"><img id="000004" he="14" wi="114" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></maths>

0024In the above equation, E is Young's modulus, ν is Poisson's ratio, t is glass thickness, σ is stress, and e₂-e₁Is the difference in thermal expansion between the clad glass and the core glass. The above equation is further simplified by using the same modulus and Poisson's ratio for the clad and core glasses.

0025To calculate the difference in thermal expansion between the clad glass and the core glass, it is assumed that the stress is below the strain point of the softer glass of the clad and core. The stress in the clad glass can be estimated using these assumptions and the above equations. 30 x 10 as clad glass^-790 × 10 alkaline aluminosilicate core glass with a coefficient of thermal expansion of / ° C^-7For typical display-like glasses with a coefficient of thermal expansion of / ° C, a total thickness in the range of 0.5 to 1.0 mm and a thickness of clad glass of 10 to 100 μm, the compressive stress of the clad glass is , Estimated to be in the range of about 200MPa to about 315MPa. As can be seen in Table 2 below, some non-alkali glass samples are about 15 to about 13 x 10^-7It has a coefficient of thermal expansion in the range of / ° C. For these glasses, the compressive stress of the clad glass layer ranges from 240 MPa to about 400 MPa.

0026The non-alkali glass described herein has a particularly low coefficient of thermal expansion. In some embodiments, the coefficient of thermal expansion averaged over a temperature range of about 20 ° C to about 300 ° C is 38 × 10.^-7It is less than / ° C. In other embodiments, the coefficient of thermal expansion of the glass averaged over a temperature range of about 20 ° C to about 300 ° C is about 20 × 10.^-7It is less than / ° C. When combined with a core glass having a higher coefficient of thermal expansion, the glass described herein results in a high level of compressive stress within the clad layer of the final laminated glass product. This increases the strength of the glass laminate. At least about 100 MPa And in some embodiments, room temperature compressive stress of at least about 400 MPa can be achieved by using the glass disclosed herein within the clad layer of the laminate.

0027Non-alkali glass has Young's modulus and shear modulus values that are significantly smaller than the Young's modulus and shear modulus of other commercially available hot-dip stretched glasses. In some embodiments, Young's modulus is less than about 78 gigapascals (GPa), in other embodiments less than about 70 GPa, and in yet other embodiments less than about 60 GPa. The low modulus provides these glasses with a high level of intrinsic damage resistance.

0028In some embodiments, these non-alkali glasses have a strain point of less than 800 ° C.

0029In some embodiments, the glasses described herein are about 50 mol% to about 75 mol% SiO.₂(That is, 50 mol% SiO₂75 mol%), over 0 mol% to about 20 mol% Al₂O₃(That is, 0 mol% &lt;Al₂O₃20 mol%), over 0 mol% to about 35 mol% B₂O₃(That is, 0 mol% &lt;B₂O₃35 mol%), P over 0 mol% to about 20 mol%₂O₅(That is, 0 mol% &lt;P₂O₅20 mol%), MgO up to about 5 mol% (ie 0 mol% MgO 5 mol%), CaO up to about 10 mol% (ie 0 mol% CaO 10 mol%), about 5 SrO up to mol% (ie 0 mol% SrO 5 mol%), Fe up to about 0.5 mol%₂O₃(That is, 0 mol% Fe₂O₃0.5 mol%), ZrO up to about 0.1 mol%₂(That is, 0 mol% ZrO₂0.1 mol%), and optionally SnO₂, CeO₂, As₂O₃, Sb₂O₅, Cl^-, F^-Etc. essentially from or include at least one fining agent. At least one fining agent, in some embodiments, SnO up to about 0.7 mol%₂(That is, 0 mol% SnO₂0.5 mol%), As up to about 0.5 mol%₂O₃(That is, 0 mol% As₂O₃0.5 mol%), and Sb up to about 0.5 mol%₂O₃(That is, 0 mol% Sb₂O₃0.5 mol%) may be contained.

0030In certain embodiments, the glass is about 55 mol% to about 72 mol% SiO.₂(That is, 55 mol% SiO₂75 mol%), over 0 mol% to about 16 mol% Al₂O₃(That is, 0 mol% &lt;Al₂O₃16 mol%), about 8 mol% to about 35 mol% B₂O₃(That is, 8 mol% B₂O₃35 mol%), about 3 mol% to about 20 mol% P₂O₅(That is, 3 mol% P₂O₅20 mol%), MgO up to about 5 mol% (ie 0 mol% MgO 5 mol%), CaO up to about 0.2 mol% (ie 0 mol% CaO 0.2 mol%), about 0.2 SrO up to mol% (ie 0 mol% SrO 0.2 mol%), ZrO up to about 0.1 mol%₂(That is, 0 mol% ZrO₂0.1 mol%) essentially consists of or contains. Glass is also SnO₂, CeO₂, As₂O₃, Sb₂O₅, Cl^-, F^-Etc. may be contained at least one kind of fining agent. At least one fining agent, in some embodiments, SnO up to about 0.2 mol%₂(That is, 0 mol% SnO₂0.2 mol%) may be contained.

0031In some embodiments, the total amount of MgO, CaO, and SrO in the glass described herein is no more than about 5 mol%, in other embodiments no more than about 0.2 mol%, and In certain embodiments, the glass is substantially free of alkaline earth modifiers.

0032The compositions of non-limiting examples of these glasses are listed in Tables 1a-d. The properties of Examples 1-20 in Tables 1a-d are listed in Table 2. Each of these oxide components of glass serves a function. Silica (SiO)₂) Is the first glass-forming oxide, which forms a network skeleton for molten glass. High purity SiO₂Has a low coefficient of thermal expansion and does not contain alkali metals. However, due to its very high melting temperature, high purity SiO₂Does not conform to the melt stretching method. Also, the viscosity curve is too high to match any core glass in the laminated structure. In some embodiments, SiO in the glass described herein₂The amount of is in the range of about 50 mol% to about 75 mol%. In other embodiments, SiO₂Concentrations range from about 55 mol% to about 72 mol%.

0033In addition to silica, three network-forming components_-Al₂O₃, B₂O₃, And P₂O_5-Is contained in the glasses described herein to achieve stable glass formation, low coefficient of thermal expansion, low Young's modulus, low shear modulus, and facilitate melting and molding. Minimizing the need for network modifiers such as alkaline or alkaline earth oxides that act to increase the coefficient of thermal expansion and modulus of elasticity by mixing all four of these network-forming components at appropriate concentrations. It is possible to achieve stable bulk glass formation while suppressing it. SiO₂Like, Al₂O₃Gives rigidity to the glass mesh. Alumina can be present in the glass in either 4- or 5-coordination. In some embodiments, the glasses described herein are from about 2 mol% to about 20 mol% Al.₂O₃Containing, and in certain embodiments, about 2 mol% to about 16 mol% Al₂O₃including.

0034Also, boron oxide (B)₂O₃) Is a glass-forming oxide used to reduce viscosity and thus improve the ability to melt and form glass. B₂O₃Can be present in either the 3-coordination or the 4-coordination in the glass mesh. 3 Coordination B₂O₃Is the most effective oxide for reducing Young's modulus and shear modulus, thus improving the intrinsic damage resistance of the glass. Therefore, the glass described herein is B.₂O₃including. In some embodiments, the glass is B up to about 35 mol%.₂O₃In other embodiments, from about 8 mol% to about 35 mol% B₂O₃Contains.

0035Phosphorus pentoxide (P₂O₅) Is the fourth network-forming component mixed in these glasses. P₂O₅Has a quasi-tetrahedral structure in the glass network, that is, it is coordinated with four oxygen atoms, but only three of them are attached to the rest of the network. The fourth oxygen is the terminal oxygen that is double bonded to the phosphorus cation. The association of boron and phosphorus in the glass mesh is SiO₂Similarly, mutual stabilization of these network-forming components within the tetrahedral arrangement can be achieved. B₂O₃Like P₂O₅Is very effective in reducing Young's modulus and shear modulus. In some embodiments, the glasses described herein are from&gt; 0 mol% to about 20 mol% P.₂O₅And in other embodiments, about 3 mol% to about 20 mol% P₂O₅including.

0036Alkaline earth oxides (MgO, CaO, and SrO) are B.₂O₃To improve the melting behavior of glass. However, they also act to increase the coefficient of thermal expansion and Young's modulus and shear modulus. In some embodiments, the glasses described herein contain up to about 5 mol% MgO, up to about 10 mol% CaO, and up to about 5 mol% SrO, and in other embodiments, It contains up to about 5 mol% MgO, up to about 0.2 mol% CaO, and up to about 0.2 mol% SrO. In some embodiments, the total amount of MgO, CaO, and SrO is about 0.2 mol% or less. In other embodiments, alkaline earth oxides are only present at trace contaminant levels (ie 100 ppm). In yet another embodiment, the glass is substantially free of alkaline earth oxides.

0037Also, glass is SnO at a small concentration that helps remove gas inclusions during melting.₂, CeO₂, As₂O₃, Sb₂O₅, Cl^-, F^-Etc. may be contained at least one kind of fining agent. In some embodiments, the glass is SnO up to about 0.7 mol%.₂, Up to about 0.5 mol% As₂O₃, And / or Sb up to about 0.5 mol%₂O₃May include. In other embodiments, at least one fining agent has SnO up to about 0.2 mol%.₂May include.

0038In addition, a small amount of ZrO is obtained by contacting the high temperature glass with the zirconia refractory material in the melting device.₂Therefore, monitoring its level in the glass may be important for determining the wear rate of the tank over time. In some embodiments, the glass is ZrO up to about 0.1 mol%.₂May be contained. Glass has a low concentration of Fe₂O₃This material is a common impurity in batch materials, although it may further contain. In some embodiments, the glass is Fe up to about 0.5 mol%.₂O₃May be contained.

0039<tables num="1a-1"><img id="000005" he="60" wi="138" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0040<tables num="1a-2"><img id="000006" he="61" wi="114" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0041<tables num="1b-1"><img id="000007" he="67" wi="138" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0042<tables num="1b-2"><img id="000008" he="65" wi="136" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0043<tables num="1c-1"><img id="000009" he="61" wi="140" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0044<tables num="1c-2"><img id="000010" he="60" wi="117" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0045<tables num="1d-1"><img id="000011" he="60" wi="139" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0046<tables num="1d-2"><img id="000012" he="59" wi="138" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0047<tables num="1d-3"><img id="000013" he="59" wi="137" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0048<tables num="1d-4"><img id="000014" he="59" wi="116" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0049<tables num="2-1"><img id="000015" he="92" wi="137" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0050<tables num="2-2"><img id="000016" he="92" wi="139" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0051<tables num="2-3"><img id="000017" he="92" wi="139" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0052<tables num="2-4"><img id="000018" he="92" wi="138" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0053<tables num="2-5"><img id="000019" he="90" wi="138" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0054<tables num="2-6"><img id="000020" he="91" wi="140" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0055<tables num="2-7"><img id="000021" he="90" wi="140" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0056<tables num="2-8"><img id="000022" he="90" wi="132" file="JP2016517841A_D0001.tif" img-format="tif" img-content="drawing" /></tables>

0057Also provided are methods of making the glasses described herein. This method is SiO₂And B₂O₃And Al₂O₃And P₂O₅The present invention comprises a step of providing a glass melt containing at least one of the above and substantially free of an alkali metal modifier, and a step of down-drawing the glass melt to form glass. In some embodiments, the step of downdrawing the glass comprises slot stretching the glass melt, and in other embodiments comprising melt stretching the glass melt.

0058In certain embodiments, the method further comprises providing a core glass melt and melt-stretching the core glass melt to form a core glass having a thermal expansion rate less than that of the clad glass. .. Next, the clad glass melt is melt-stretched to form a clad glass layer, thereby surrounding the core glass. The clad glass layer is under compressive stress of at least about 400 MPa.

0059The glasses described herein are substantially free of alkali metals and are therefore suitable for use in thin film transistor (TFT) display applications. These applications require a non-alkali interface as the presence of alkaline ions contaminates the thin film transistor. Therefore, ion-exchanged alkali-containing glass is not suitable for such applications. The glass laminates described herein using non-alkali glass as a clad layer provide tempered glass products in combination with a non-alkali interface. In some embodiments, the non-alkali glass also has high annealing and strain points that reduce thermal consolidation, which is desirable for TFT display substrates. The glasses described herein may also be used in color filter transistor substrates, cover glasses, or touch interfaces for various electronic devices.

0060Although typical embodiments have been presented for explanatory purposes, the above description should not be considered to impose restrictions on the scope of the present disclosure or the appended claims. Therefore, various improved, modified, and alternative forms will be conceivable to those skilled in the art without departing from the spirit and scope of the present disclosure or the appended claims.