Glass

Abstract

An alkali-free glass of the present invention includes as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 5% of B.sub.2O.sub.3, 3% to 10% of MgO, 7% to 20% of SrO, and 0% to 5% of BaO, is substantially free of an alkali metal oxide, and has a strain point of more than 720° C.

Claims

1. A glass, comprising as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 5% of B.sub.2O.sub.3, 0% to 0.5% of Li.sub.2O+Na.sub.2O+K.sub.2O, 4.4% to 10% of MgO, 7% to 13% of SrO, and 0% to 5% of BaO, and having a strain point of 740° C. or more, wherein a ratio of CaO/MgO in terms of mass % is 0.7 or less.

2. The glass according to claim 1, comprising as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to less than 3% of B.sub.2O.sub.3, 0% to less than 0.1% of Li.sub.2O+Na.sub.2O+K.sub.2O, 4.4% to 10% of MgO, 0.1% to 4% of CaO, 8% to 13% of SrO, and 0.1% to 4% of BaO.

3. The glass according to claim 2, comprising 2.2 mass % to 4 mass % of BaO.

4. The glass according to claim 2, comprising 0.1 mass % to 3 mass % of CaO.

5. The glass according to claim 1, wherein the glass has a ratio of CaO/SrO in terms of mass % of 0.4 or less.

6. The glass according to claim 1, further comprising 0.001 mass % to 1 mass % of SnO.sub.2.

7. The glass according to claim 1, wherein the glass has a specific Young's modulus of more than 29.5 GPa/g.Math.cm.sup.−3.

8. The glass according to claim 1, wherein the glass has a liquidus temperature of less than 1,320° C.

9. The glass according to claim 1, wherein the glass has a temperature at a viscosity at high temperature of 10.sup.2.5 dPa.Math.s of 1,660° C. or less.

10. The glass according to claim 1, wherein the glass has a viscosity at a liquidus temperature of 10.sup.4.0 dPa.Math.s or more.

11. The glass according to claim 1, wherein the glass has a flat sheet shape and comprises overflow-joined surfaces in a middle portion thereof in a sheet thickness direction.

12. The glass according to claim 1, wherein the glass is used for an OLED.

13. The glass according to claim 1, comprising 0.1 mass % to 5 mass % of BaO.

14. The glass according to claim 1, comprising 2.2 mass % to 5 mass % of BaO.

15. The glass according to claim 1, comprising 0.1 mass % to 3 mass % of CaO.

Description

EXAMPLES

(1) The present invention is hereinafter described by way of Examples.

(2) Examples of the present invention (Sample Nos. 1 to 19) are shown in Table 1. In Table 1, the “N.A.” means that the item is not measured. The content of Fe.sub.2O.sub.3 in each sample is not explicitly shown in Table 1, but each sample contains 0.001 mass % to 0.008 mass % of Fe.sub.2O.sub.3 as an impurity in a glass composition. In addition, the β-OH value in each sample is not explicitly shown in Table 1, but was from 0.05/mm to 0.15/mm.

(3) TABLE-US-00001 TABLE 1 No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No. 10 Composition (mass %) SiO.sub.2 62.5 63.2 63.8 62.0 63.1 61.3 61.8 61.8 60.9 62.3 Al.sub.2O.sub.3 17.3 17.3 15.9 18.7 15.9 18.7 17.4 21.0 21.0 21.2 B.sub.2O.sub.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 2.0 1.0 Li.sub.2O 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na.sub.2O 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 K.sub.2O 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 MgO 5.6 5.0 5.6 4.9 6.2 5.5 6.2 4.5 4.4 4.5 CaO 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.8 SrO 14.3 14.3 14.4 14.2 14.5 14.3 14.4 11.4 11.4 10.0 BaO 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO.sub.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO/MgO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.19 CaO/SrO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 Property α30-380 40.5 39.9 40.9 39.9 42.5 40.2 41.2 35.4 35.8 35.3 (×10.sup.−7/° C.) Density (g/cm.sup.3) 2.649 2.638 2.644 2.670 2.671 2.659 2.662 2.595 2.590 2.581 HF etching rate N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. (μm/min.) Ps (° C.) 754 758 750 761 743 757 749 762 750 760 Ta (° C.) 809 814 805 818 797 812 804 820 807 817 Ts (° C.) 1,033 1,042 1,031 1,043 1,015 1,032 1,023 1,047 1,032 1,045 10.sup.4.5 dPa .Math. s (° C.) 1,283 1,299 1,286 1,295 1,259 1,278 1,267 1,303 1,281 1,297 10.sup.4.0 dPa .Math. s (° C.) 1,343 1,361 1,348 1,356 1,318 1,338 1,326 1,365 1,341 1,357 10.sup.3.0 dPa .Math. s (° C.) 1,503 1,524 1,510 1,516 1,476 1,494 1,483 1,527 1,496 1,512 10.sup.2.5 dPa .Math. s (° C.) 1,607 1,627 1,616 1,619 1,580 1,594 1,585 1,629 1,595 1,610 TL (° C.) 1,305 1,315 1,281 N.A. 1,273 N.A. 1,311 1,310 1,292 1,305 Logη at TL 4.31 4.37 4.54 N.A. 4.38 N.A. 4.13 4.44 4.41 4.43 (dPa .Math. s) Young's modulus 84.7 84.0 83.8 85.0 84.8 85.6 85.5 85.0 84.0 85.5 (GPa) Specific modulus 32.0 31.8 31.7 31.8 31.8 32.2 32.1 32.7 32.4 33.1 (GPa/g .Math. cm.sup.−3) No. 11 No. 12 No. 13 No. 14 No. 15 No. 16 No. 17 No. 18 No. 19 Composition (mass %) SiO.sub.2 61.4 62.7 61.8 60.9 61.3 60.4 61.7 60.9 60.0 Al.sub.2O.sub.3 20.9 21.3 21.0 20.7 21.1 20.8 21.3 21.0 20.7 B.sub.2O.sub.3 1.0 1.0 1.0 1.0 2.1 2.0 2.1 2.0 2.0 Li.sub.2O 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na.sub.2O 0.03 0.00 0.00 0.03 0.00 0.02 0.02 0.02 0.02 K.sub.2O 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.00 MgO 4.4 4.5 4.4 4.4 4.5 4.4 4.5 4.4 4.4 CaO 0.0 1.7 0.8 0.0 0.8 0.0 1.7 0.8 0.0 SrO 9.8 8.5 8.4 8.3 10.0 9.8 8.5 8.4 8.3 BaO 2.2 0.0 2.3 4.5 0.0 2.2 0.0 2.3 4.4 SnO.sub.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO/MgO 0.00 0.37 0.19 0.00 0.19 0.00 0.37 0.19 0.00 CaO/SrO 0.00 0.20 0.10 0.00 0.08 0.00 0.20 0.10 0.00 Property α30-380 35.3 35.1 35.5 36.4 35.7 36.2 35.3 35.6 36.4 (×10.sup.−7/° C.) Density (g/cm.sup.3) 2.609 2.566 2.594 2.625 2.575 2.602 2.561 2.589 2.618 HF etching rate 1.0 N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. (μm/min.) Ps (° C.) 761 760 760 761 748 748 746 746 748 Ta (° C.) 819 816 817 819 805 806 803 804 806 Ts (° C.) 1,048 1,043 1,047 1,050 1,031 1,033 1,029 1,032 1,035 10.sup.4.5 dPa .Math. s (° C.) 1,303 1,295 1,301 1,308 1,283 1,285 1,279 1,281 1,287 10.sup.4.0 dPa .Math. s (° C.) 1,364 1,355 1,361 1,370 1,343 1,345 1,339 1,340 1,347 10.sup.3.0 dPa .Math. s (° C.) 1,523 1,513 1,519 1,528 1,497 1,501 1,494 1,497 1,503 10.sup.2.5 dPa .Math. s (° C.) 1,622 1,612 1,617 1,627 1,596 1,602 1,592 1,596 1,602 TL (° C.) 1,305 1,324 1,322 1,314 1,298 1,283 1,310 1,291 1,281 Logη at TL 4.48 4.25 4.32 4.45 4.37 4.52 4.47 4.41 4.55 (dPa .Math. s) Young's modulus 84.7 85.9 85.2 84.4 84.5 83.8 84.9 84.1 N.A. (GPa) Specific modulus 32.5 33.5 32.8 32.1 32.8 32.2 33.1 32.5 N.A. (GPa/g .Math. cm.sup.−3)

(4) First, a glass batch prepared by blending glass raw materials so that each glass composition listed in Table 1 was attained was placed in a platinum crucible, and then melted at from 1,600° C. to 1,650° C. for 24 hours. When the glass batch was dissolved, molten glass was stirred to be homogenized by using a platinum stirrer. Next, the molten glass was poured on a carbon sheet and formed into a sheet shape, followed by being annealed at a temperature around an annealing point for 30 minutes. Each of the resultant samples was evaluated for its average thermal expansion coefficient α within a temperature range of from 30° C. to 380° C., density, β-OH value, etching rate in HF, strain point Ps, annealing point Ta, softening point Ts, temperature at a viscosity at high temperature of 10.sup.4.5 dPa.Math.s, temperature at a viscosity at high temperature of 10.sup.4.0 dPa.Math.s, temperature at a viscosity at high temperature of 10.sup.3.0 dPa.Math.s, temperature at a viscosity at high temperature of 10.sup.2.5 dPa.Math.s, liquidus temperature TL and liquidus viscosity log η at TL, Young's modulus (Young's modulus), and specific Young's modulus (Specific modulus).

(5) The average thermal expansion coefficient α within a temperature range of from 30° C. to 380° C. is a value measured with a dilatometer.

(6) The density is a value measured by a well-known Archimedes method.

(7) The etching rate in HF is a value calculated from an etching depth when, after part of a surface of the resultant glass, which has been mirror polished, is masked with a polyimide tape, the glass is etched under the conditions of 30 minutes in a 10 mass % HF aqueous solution at 20° C.

(8) The strain point Ps, the annealing point Ta, and the softening point Ts are values measured in accordance with methods of ASTM C336 and C338.

(9) The temperatures at viscosities at high temperature of 10.sup.4.5 dPa.Math.s, 10.sup.4.0 dPa.Math.s, 10.sup.3.0 dPa.Math.s, and 10.sup.2.5 dPa.Math.s are values measured by a platinum sphere pull up method.

(10) The liquidus temperature TL is a value obtained by measuring a temperature at which a crystal (initial phase) precipitates when glass powder which has passed through a standard 30-mesh sieve (sieve opening: 500 μm) and remained on a 50-mesh sieve (sieve opening: 300 μm) is placed in a platinum boat and kept for 24 hours in a gradient heating furnace.

(11) The liquidus viscosity log.sub.10ηTL is a value obtained by measuring the viscosity of a glass at the liquidus temperature TL by a platinum sphere pull up method.

(12) The Young's modulus is a value measured by a well-known resonance method. The specific Young's modulus is a value obtained by dividing the Young's modulus by the density.

(13) As apparent from Table 1, each of Sample Nos. 1 to 19 had small contents of alkali metal oxides, and had a strain point of 743° C. or more, a temperature at a viscosity at high temperature of 10.sup.2.5 dPa.Math.s of 1,629° C. or less, a liquidus temperature of 1,324° C. or less, a viscosity at a liquidus temperature of 10.sup.4.13 dPa.Math.s or more, and a specific Young's modulus of 31.7 GPa/g.Math.cm.sup.−3 or more. Therefore, it is considered that each of Sample Nos. 1 to 19 can be suitably used as a substrate for an OLED display.