GB1178175A - Method of Application of Diffusing-and-Reflecting Coatings on Interior Surfaces of Incandescent Lamp Bulbs - Google Patents

Abstract

1,178,175. Coated incandescent lamp bulb. RIZHSKY ELEKTROLAMPOVY ZAVOD. 6 March, 1967, No. 10434/67. Heading B2K. [Also in Division H1] A diffusing-and-reflecting coating is provided on the inside of an incandescent lamp bulb by applying a coat of paint containing nitro cellulose in butyl acetate as binder to the interior of the bulb, subjecting the painted bulb to drying by feeding inside the bulb a stream of air preheated to up to 25‹ Centigrade and simultaneously passing over the exterior of the bulb air heated to a higher temperature, firing the bulb in an oxidising atmosphere, cooling the bulb and maintaining it unsealed in a humid atmosphere to bring about gel formation, drying the bulb by feeding inside a stream of preheated air and simultaneously heating the bulb exterior, wetting the paint on the internal surface of the bulb with simultaneously removal of the paint and, prior to assembly of a lamp, firing the bulb at 350 to 400‹ Centigrade, and thereafter cooling. In an embodiment, the inside of a glass bulb is coated with a paint composed of magnesium oxide, barium sulphate, titanium dioxide and a solution of nitro cellulose in butyl acetate by placing the open end of the bulb over the paint so as to be sealed thereby and evacuating the bulb. The bulb is dried by feeding inside the bulb a stream of air at 18 to 25‹ Centigrade whilst purging the bulb exterior with air at 40 to 60‹ Centigrade. The bulbs are then fired in an oxidising atmosphere at 460 to 500‹C. A fired coating is moistened by maintaining in an atmosphere at 18 to 25‹C., R.H. 70 to 80%, or steaming at 40‹C., R.H. 95 to 98%. The paint is removed in the sealing zone of the bulb by mechanical means e.g. flushing with a water jack and scraping off paint with rubber brushes. The bulbs are then dried by feeding inside a stream of air preheated to 60 to 70‹C. and simultaneously heating the exterior of the bulb 70 to 80‹C. The gel is dehydrated by firing the bulbs at 350 to 400‹C. followed by slow cooling.