| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a chemically reinforced plate glass which is improved in brittleness inherent in glass, and is prevented from the occurrence of the extension of unavoidable remaining cracks that are formed during processing, and in which a deep surface stress layer is likely to be produced to enable the easy incorporation of the remaining cracks into the surface compression stress layer, and scratches are hardly formed by external forces. <P>SOLUTION: The chemically reinforced plate glass includes 75.5 to 85.5% of SiO<SB POS="POST">2</SB>, 1 to 8% of MgO, 0 to 7% of CaO, 0 to 5% of Al<SB POS="POST">2</SB>O<SB POS="POST">3</SB>, and 10 to 22.5% of Na<SB POS="POST">2</SB>O in terms of oxide in mass percentage, wherein the content of MgO is higher than that of CaO, the total content of MgO and CaO (MgO+CaO) is 8% or less, the total content of MgO, CaO and Na<SB POS="POST">2</SB>O is 24.5% or less, and the ratio calculated by dividing the (MgO+CaO) content by the Na<SB POS="POST">2</SB>O content is 0.45 or less. <P>COPYRIGHT: (C)2012,JPO&INPIT |
