GB852270A - Process for improving the resistance of glass surfaces to the action of liquids, more especially water, and moisture contained in air or gas - Google Patents

Abstract

852,270. Treatment of glass surfaces. DEUTSCHE TAFELGLAS AKTIENGESELLSCHAFT DETAG. May 26, 1959 [June 21, 1958], No. 17966/59. Class 56. In a process for improving the resistance of glass surfaces to the action of liquids, more especially water and moisture contained in air or gas, in which the hot glass surface is treated with halides of metals such as aluminium zirconium or zinc which have an amphoteric action or form weakly basic oxides, a hot gas stream is directed towards the glass surface, the stream having added or included therein in addition to the said halides, substances which are able to form halides from the amphoteric oxides of the metals and consist more especially of halides of sulphur and/or carbon. Aluminium chloride and carbon tetrachloride are preferred or the bromides may be substituted. As shown in Fig. 3, a glass sheet 11 drawn upwards by rollers 13, 14, 15 is treated while still hot in the upper part 12 of the drawing apparatus by vaporising boxes 17 on each side. Carbon tetrachoride is introduced through supply pipes 21 and is vaporised by the heat of the glass 11 to form a concentrated stream 20 which passes through a porous plate 18 which consists of alumina, to form aluminium chloride, the two chlorides reacting on the sheet 11. A second porous plate 19 may be arranged inwardly of the plate 18, the plates either being of the same material or the plate 19 of a material reacting relatively easily with the carbon tetrachloride and that of the plate 18 less easily. In a further arrangement, not shown, the vaporiser box has secured above, more or less centrally, a container from which the carbon tetrachloride drips continually followed by a container for anhydrous aluminium chloride with a porous section fitting across the vaporiser box, and a hot air stream being passed through the box becomes saturated with carbon tetrachloride and picks up small quantities of and volatizes the aluminium chloride before reaching the glass sheet 11. As shown in Fig. 5, for treating the insides of hollow glass containers 29 intermittently brought on a conveyor 30 to a position under a vaporiser unit 25, the unit 25 can be supplied with carbon tetrachloride from a pipe 27 and has a depending porous hollow element 26 consisting of a metal oxide which can be lowered to the position shown inside the hollow container 29 when the stream of carbon tetrachloride is started. After the surface has been treated, the stream of carbon tetrachloride is stopped and the element 26 is then raised to lie between the two parts of an electric furnace 28 which are moved to enclose the element 26 while the next container 29 is moved into position.