Patent ID: 8728961
Filing Date: 2014-05-20
Classification: C03B,C03C

Abstract:
1. A flat glass that is subsequently convertible into a glass ceramic, said flat glass having a thickness that is below an equilibrium thickness of a glass melt on a metal bath, said flat glass having a net width of more than one meter, and said flat glass containing no more than 50 crystals per kilogram with a size of greater than 50 μm within the net width, and wherein said flat glass is made from said glass melt, and wherein said flat glass is made by a method comprising the steps of: a) feeding melted crystallizable glass of a predetermined composition onto a metal bath; b) forming a continuous glass sheet of a predetermined thickness on the metal bath from the melted crystallizable glass of the predetermined composition on the metal bath by drawing the glass sheet, so that said predetermined thickness is less than an equilibrium thickness of the melted crystallizable glass on the metal bath; c) conducting the glass sheet through different zones, said different zones having different temperatures; d) cooling the glass sheet during passage through said zones from an upper temperature to a lower devitrification point (UEG) of the crystallizable glass with a first cooling rate according to formula (I): wherein said upper temperature is in a temperature range from 15° C. above a temperature (T e) during the forming of the glass sheet by the drawing, cooling the melted crystallizable glass on the metal bath at temperatures above said upper temperature with a second cooling rate that is smaller than said first cooling rate; and f) subsequently continuously drawing the glass sheet off the metal bath, whereby said flat glass is formed.