Barium aluminosilicate glasses

• US 5,326,730 A
• Filed: 05/17/1993
• Issued: 07/05/1994
• Est. Priority Date: 01/22/1993
• Status: Expired due to Term

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Lapp, Josef C., Dumbaugh, William H. Jr.
• Primary Examiner(s): Green, Anthony
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/061,459
• Time in Patent Office: 414 Days
• Field of Search: 501/69, 501/63, 501/66, 501/67, 359/82
• US Class Current: 501/69
• CPC Class Codes: C03C 3/085 containing an oxide of a divalent metal
• CPC Class Codes: C03C 3/093 containing zinc or zirconium
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum

Abstract

This invention is directed to glass compositions particularly designed for use as substrates in flat panel display devices and, more expressly, for use as substrates in LCDs which employ polycrystalline silicon thin film transistors. The glass compositions are essentially free from alkali metal oxides and consist essentially, in mole percent, of

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SiO₂ 65-76 MgO 0-5 ZrO₂ 0-2.5 Al₂ O₃ 7-11 CaO 0-10 TiO₂ 0-3 BaO 12-19 SrO 0-10 Ta₂ O₅ 0-3 B₂ O₃ 0-5 MgO + 0-15 ZrO₂ + 0.5-5. CaO + TiO₂ + SrO Ta₂ O₅ ______________________________________

Claims

1. A glass exhibiting a strain point higher than 660°

C., a liquidus temperature no higher than 1,175°

C., a weight loss of less than 1 mg/cm² after immersion for 24 hours in an aqueous 5% by weight HCl solution at 95°

C., and long term stability against devitrification at melting and forming temperatures, said glass being essentially free from alkali metal oxides and consisting essentially, expressed in terms of mole percent on the oxide basis, of

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 65-76 MgO 0-5 Al.sub.2 O.sub.3 7-11 CaO 0-10 TiO.sub.2 0-3 BaO 12-19 SrO 0-10 Ta.sub.2 O.sub.5 0-3 B.sub.2 O.sub.3 0-5 MgO + 0-15 TiO.sub.2 + 0.5-5. CaO + Ta.sub.2 O.sub.5 SrO ______________________________________

2. A glass according to claim 1 consisting essentially of

3. In a liquid crystal display device which employs polycrystalline silicon thin film transistors as switches, which device contains a flat, transparent glass substrate, the improvement wherein said glass exhibits a strain point higher than 660°

C., a liquidus temperature no higher than 1,175°

C., a weight loss of less than 1 mg/cm² after immersion for 24 hours in an aqueous 5% by weight HCl solution at 95°

C., and long term stability against devitrification at melting and forming temperatures, said glass being essentially free from alkali metal oxides and consisting essentially, expressed in terms of mole percent on the oxide basis, of

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 65-76 MgO 0-5 Al.sub.2 O.sub.3 7-11 CaO 0-10 TiO.sub.2 0-3 BaO 12-19 SrO 0-10 Ta.sub.2 O.sub.5 0-3 B.sub.2 O.sub.3 0-5 MgO + 0-15 TiO.sub.2 + 0.5-5. CaO + Ta.sub.2 O.sub.5 SrO ______________________________________

4. In a liquid crystal display device according to claim 3 wherein said glass consists essentially of