Patent ID: 7341968

Claim:
A glass plate which has the following composition: SiO 2 66.0-74.0 mass %, Al 2 O 3 2.0-4.0 mass %, CaO 7.0-10.0 mass %, MgO 3.8-6.0 mass %, Na 2 O 12.6-14.6 mass % and K 2 O 0.4-2.0 mass %, in a total amount of these components of at least 96 mass %, and SiO 2 +Al 2 O 3 70.0-74.0 mass %, CaO+MgO 12.5-14.5 mass %, Na 2 O K 2 O 13.5-15.5 mass %, and CaO/MgO (mass ratio)=1.7-2.2, and which has a linear thermal expansion coefficient of at least 90×10 −7 and a softening point of from 720 to 735° C.