Chemical surface hardening of glassware, esp. bottles - by ion exchange using salt mixt. carried into bottle by compressed air employed for final moulding of bottle

摘要

The internal and/or external surfaces of a container or bottle made of glass are hardened by exchanging alkali ions (I) of a smaller atomic vol. in the surface of the glass with alkali ions (II) of a larger atomic vol. Ions (II) are obtd. from a dry material (IIa), which is fed by a carrier onto the glass while the latter is being moulded and is above 100 deg.C, so material (IIa) melts partly or completely when it impinges on the glass. Material (IIa) is pref. a salt mixt. contg. by wt. more than 50% of alkalies contg. ions (II); plus more than 20% other salts which melt when meeting the hot glass; and after ion exchange, the residual salt mixt. is completely soluble in water. The compressed air used to mould the glass is pref. employed to carry the salt mixt. (IIa). Chemical surface hardening can be included in the normal glass moulding process.