The use of silicones in the glass industry

JSGT 1958 V42 T189-T194

The thermal stability and low volatility of silicones allied with their very pronounced anti-sticking properties make them ideally suitable for a number of applications in the glass industry. In the manufacture of glass bottles and jars on rotary and independent section automatic moulding machines large amounts of hydrocarbon oils are normally used in lubricating the delivery equipment in order to facilitate the passage of the gob of molten glass to the blank mould. This oil gives rise to undesirable fumes and smoke which are an ever-present fire hazard in glass works. Recent trials with a newly developed emulsion of a polysiloxane fluid have shown that when this emulsion is diluted with water to a silicone content of 0·5 to 1·0% it can replace the traditional hydrocarbon oils for delivery lubrication and at the same time eliminate all the smoke and fume formerly associated with gob delivery. Although it is doubtful if the silicone is stable for any appreciable time at the temperature of molten glass, excellent lubricity to the gob is imparted by the emulsion which is sprayed on to the delivery equipment in pulses just immediately before the passage of the gob. The silicone emulsion can be used as a direct replacement for the hydrocarbon oil mixture in the spray equipment normally fitted to glass moulding machines where the mould lubrication and delivery lubrication systems are separate. More accurate metering and application of the silicone emulsion can be obtained by using automatic paint spraying equipment, and in cases where a single combined delivery and mould lubrication system is used, this type of auxiliary spray equipment is necessary for applying silicones separately to the delivery system.

A. Butchart