| 摘要 |
PROBLEM TO BE SOLVED: To prevent the damage at the time of handling at a low cost by applying a reinforcing salt solution, in which a thickener is added, on the optional part such as the edge end surface of a glass plate product and heat treating it to introduce a chemically reinforced layer on the surface of the glass to efficiently reinforce the glass at high productivity. SOLUTION: Only a part necessary for being reinforced in the glass plate product, particularly the edge part is coated with the reinforcing salt solution, in which the thickener is added to be about 0.01-1,000 poise in viscosity and heat treated at a temp. equal to or below the glass transition temperature of the glass after dried. The reinforcing salt in the reinforcing salt solution is constituted of nitrate, chloride, peroxide salt, perchlorate or the like of an alkali metal. As the thickener, a food additive base or the derivative such as curdlan, cellulose is used. The glass is reinforced by ion-exchanging between the glass and the reinforcing salt by the heat treatment to form a compressive stress layer on the glass inner surface. The reinforcing treatment is preferably continuously applied using a belt conveyer in the production line of a glass substrate or the like.
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