| 摘要 |
PURPOSE:To provide an effective means for preventing warpage of even a float glass having a scratch-proofing protection film on the surface, by holding the glass plate in an immersion holder in a specific state in the immersion treatment of a glass plate in a molten salt (e.g. Na ion) which is a preparatory stage for the chemical reinforcement of a float glass. CONSTITUTION:A float glass plate I is subjected to chemical reinforcement e.g. by a low-temperature ion exchange method. As a preparatory stage of the above process, the plate is immersed in a molten salt containing Na ion and/or Li ion. In the above immersion process, the plate is held in an immersion holder at an inclination angle of +0-15 deg. (holding angle 2) facing the top surface 5 (the surface free from contact with molten thin in production process) upward.
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