A method for the increase of the mechanical and the abrasion resistance of sodium oxide containing glass by the exchange of ions in the surfaces layer of the glass and by its surface with a protective coat it

摘要

1286516 Coating glass BROCKWAY GLASS CO Inc 22 Oct 1969 [10 Dec 1968] 51790/69 Heading B2E [Also in Division C1] A glass body is strengthened by treating the surface of the glass with a pyrolyzable compound of Sn, Ti or Zr at an elevated temperature so as to form the corresponding metal oxide on the glass surface, spraying the said surface with an aqueous solution of potassium at an elevated temperature so as to form a film of the salt on the glass surface, and maintaining the glass at an elevated temperature while sodium ions in the glass are replaced by potassium ions so as to form a compressively stressed surface layer, cooling the glass and washing off excess salt, and coating the glass with an olefin polymer. The pyrolyzable compound may be applied by spraying or by exposing the glass to the vapour of the compound, and may be stannic chloride, an alkyl titanate, e.g. tetrabutyl titanate, tetraisopropyl titanate, tetrakis (2-ethylhexyl)titanate, or a titanium tetrahalide, e.g. titanium tetrachloride, as well as the corresponding zirconium compounds. The potassium salt may be tripotassium phosphate, dipotassium hydrogen phosphate or potassium carbonate. The olefin polymer may be a polymer of a lower alkene, e.g. ethylene, propylene, butylene. These may be applied as solutions or emulsions. A suitable emulsion is, in parts by weight:- Polyethylene 40 Oleic acid 11 Potassium hydroxide 2 Water 407 this being sprayed onto the glass surface.