Patent GB-760573-A (GB)
Title: Process for the production of polysiloxane coatings on glass surfaces
IPC: C03C17/30
Filed: 1953-03-23
Abstract: Aqueous organopolysiloxane emulsions suitable for the production of hydrophobic coatings on glass articles, such as glasses, bottles, ampoules, laboratory utensils and house or shop windows, contain emulsifying agents which are capable of being volatilized during the hardening of the coating or of being washed out of the coating with water prior to the hardening.  The emulsions may be made by dissolving the siloxanes, e.g. methyl-polysiloxane resins alone or together with siloxane oils, in solvents miscible with water, e.g. methyl, ethyl, propyl, isopropyl or butyl alcohols, with or without acetone, with the addition of alkylamines as emulsifiers, and pouring the mixture into water.  The emulsions may be stabilized by the addition of a fatty acid, e.g. oleic acid.  Emulsifiers specified are di- and tri-ethylamines and triethanolamine oleate.  Examples are given.ALSO:In the production of hydrophobic coatings on dry or wet surfaces of glass articles such as glasses, bottles, ampoules, laboratory utensils and house or shop windows, by treating the surfaces with an acqueous emulsion of an organopolysiloxane and subsequently hardening the resulting coatings, the siloxane emulsion used is one in which the emulsifier is volatile at or below the hardening temperature of the siloxane coating and volatilzes during the hardening, or one in which the emulsifier is nonvolatile and is washed out of the siloxane coating with water prior to the heat hardening treatment (see Group IV(a)). The coating of the articles may be effected by spraying or rinsing with the emulsions and then heating at temperaturs up to 200 DEG C. Removal of excess emulsion by washing with water prior to hardening ensures a more uniform coating. In examples, small bottles and ampoules are cleaned and washed, rinsed internally with siloxane emulsions and then rinsed with distilled water, the liquid used at each stage preferably being recycled.  The coated bottles and ampoules are then heated at 200 DEG C. for 1 1/2 to 2 hours, which effects hardening of the siloxane films and sterilization of the bottles and ampoules.ALSO:In the production of hydrophobic coatings on dry or wet surfaces of glass ampoules and bottles intended for pharmaceutical purposes by treating the surfaces with an aqueous organopolysiloxane emulsion and subsequently hardening the resulting coating, the siloxane emulsion used is one in which the emulsifier is volatile at or below the hardening temperature of the siloxane coating and volatilises during the hardening, or one in which the emulsifier is non-volatile and is washed out of the siloxane coating with water prior to the heat hardening treatment (see Group IV(a)).  The emulsions may be applied by spraying or rinsing.  Removal of excess emulsion from the surfaces by washing with water prior to hardening ensures a more uniform coating.  In examples, small bottles and ampoules are cleaned and washed, rinsed internally with the siloxane emulsions and then rinsed with distilled water, the liquid used at each stage preferably being recycled.  The coated bottles and ampoules are then heated at 200 DEG C. for 1 1/2 to 2 hours, which effects hardening of the siloxane films and sterilization of the bottles and ampoules.