Alkali-free glass substrate and process for producing the same
AssigneeNippon Electric Glass Co., Ltd.
InventorsYoshinari Kato, Tatsuya Takaya
Life of this patent
Estimating the term…
Abstract
The invention provides an alkali-free glass substrate small in the variation of the thermal shrinkage and a process for producing the same. An alkali-free glass substrate of the invention has an absolute value of a thermal shrinkage of 50 ppm or more when the alkali-free glass substrate is heated at a rate of 10° C./min from a room temperature, kept at a holding temperature of 450° C. for 10 hr and then cooled at a rate of 10° C./min.
Claims11
A process for producing an alkali-free glass substrate comprising melting a glass raw material and forming a glass sheet by an overflow down draw method, wherein, in a cooling step during said forming, an average cooling rate in a temperature range from an annealing point to a temperature lowered by 100° C. from the annealing temperature is 300° C./min or more, and wherein the alkali-free glass substrate has an absolute value of a thermal shrinkage of 50 ppm or more when the alkali-free glass substrate is heated at a rate of 10° C./min from a room temperature, kept at a holding temperature of 450° C. for 10 hours, and then cooled at a rate of 10° C./min, wherein the produced alkali-free glass substrate comprises, by weight %, 50 to 70% of SiO2, 1 to 20% of Al2O3, 0 to 15% of B2O3 to 30% of MgO, 0 to 30% of CaO, 0 to 30% of SrO and 0 to 30% of BaO.
A process for producing an alkali-free glass substrate comprising melting a glass raw material and forming a glass sheet by an overflow down draw method, wherein, in a cooling step during said forming, an average sheet drawing rate in a temperature range from an annealing point to a temperature lowered by 100° C. from the annealing temperature is 150 cm/min or more and an average cooling rate in the temperature range from the annealing point to the temperature lowered by 100° C. from the annealing temperature is 300° C./min or more, wherein the produced alkali-free glass substrate comprises, by weight %, 50 to 70% of SiO2, 1 to 20% of Al7O3, 0 to 15% of B2O3, 0 to 30% of MgO, 0 to 30% of CaO, 0 to 30% of SrO and 0 to 30% of BaO.
A process for producing an alkali-free glass substrate comprising melting a glass raw material and forming a glass sheet by an overflow down draw method, wherein, in a cooling step during said forming, an average cooling rate in a temperature range from an annealing point, which is greater than a strain point of the substrate, to a temperature lowered by 100° C. from the annealing temperature is 300° C./min or more, wherein the glass substrate has a variation of the thermal shrinkage when the cooling rate is varied by 60° C./min of 3 ppm or less, and, wherein the produced alkali-free glass substrate comprises, by weight %, 50 to 70% of SiO2, 1 to 20% of Al2O3, 0 to 15% of B2O3, 0 to 30% of MgO, 0 to 30% of CaO, 0 to 30% of SrO and 0 to 30% of BaO.
Dependencies are inferred from the claim text.