METHOD FOR PRODUCING GLASS SHEET

摘要

A method for producing a glass sheet, said method comprising: (I) a step for contacting at least one main surface of a glass material, said glass material containing at least sodium as a component, having a temperature that is not lower than the glass transition point and not higher by 250°Cthan the glass transition point and having been shaped into a sheet form, with a first acidic gas, said first acidic gas not containing hydrogen chloride (HCl) gas but containing hydrogen fluoride (HF) gas and having a ratio by volume of water vapor to the HF gas of lower than 8; (II) a step, which is to be conducted before or after the aforesaid step (I), for contacting the main surface with a second acidic gas, said second acidic gas containing HCl gas and, in the case of containing HF gas, containing water vapor in such an amount that the ratio by volume of the water vapor to the HF gas becomes 8 or higher; and (III) a step for cooling the glass material, which has been subjected to the aforesaid steps (I) and (II), to give a glass sheet.