초록 ▼

A glass composition for a substrate consisting essentially of from 59 to 72 wt % of SiO.sub.2, from 1 to 15 wt % of Al.sub.2 O.sub.3, from 0.5 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 6 wt % of SrO, from 0 to 5 wt % of BaO, from 4 to 19 wt % of MgO+CaO+SrO+BaO, from 0 to 9 wt % of Na.

A glass composition for a substrate consisting essentially of from 59 to 72 wt % of SiO.sub.2, from 1 to 15 wt % of Al.sub.2 O.sub.3, from 0.5 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 6 wt % of SrO, from 0 to 5 wt % of BaO, from 4 to 19 wt % of MgO+CaO+SrO+BaO, from 0 to 9 wt % of Na.sub.2 O , from 4 to 21 wt % of K.sub.2 O, from 10 to 22 wt % of Na.sub.2 O+K.sub.2 O, and from 0.5 to 10.5 wt % of ZrO.sub.2, wherein the difference between the SiO.sub.2 content and the Al.sub.2 O.sub.3 content is from 50 to 71 wt %, and the specific gravity of the composition is less than 2.6.

대표청구항 ▼

[ What is claimed is:] [1.] A glass composition for a substrate consisting essentially of from 59 to 72 wt % of SiO.sub.2, from 1 to 15 wt % of Al.sub.2 O.sub.3, from 0.5 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 6 wt % of SrO, from 0 to at most 0.4 wt % of BaO, from 4 to 19 wt % of Mg

[ What is claimed is:] [1.] A glass composition for a substrate consisting essentially of from 59 to 72 wt % of SiO.sub.2, from 1 to 15 wt % of Al.sub.2 O.sub.3, from 0.5 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 6 wt % of SrO, from 0 to at most 0.4 wt % of BaO, from 4 to 19 wt % of MgO+CaO+SrO+BaO, from 0 to 9 wt % of Na.sub.2 O, from 4 to 21 wt % of K.sub.2 O, from 10 to 22 wt % of Na.sub.2 O+K.sub.2 O, and from 0.5 to 10.5 wt % of ZrO.sub.2, wherein the difference between the SiO.sub.2 content and the Al.sub.2 O.sub.3 content is from 50 to 71 wt %, and the specific gravity of the composition is less than 2.6.