GB732565A - Method of applying a film of organic material to phosphor layer and composition therefor - Google Patents

Abstract

A film-forming composition for use in making cathode-ray tubes (see Group XL (a)) comprises a small proportion of nitro-cellulose, a water-insoluble plasticizer therefor and an octyl acetate (preferably 2-ethyl hexyl acetate) dissolved in a mixture comprising a propyl and/or a butyl alcohol and a propyl and/or a butyl acetate, the acetate(s) being the major constituent of the composition. The plasticizer may be castor oil, a phthalate, such as dioctyl, diallyl, dibutyl, dicapryl, diethylene glycol, diphenyl, glycerol or methyl "Cellosolve" (Registered Trade Mark) phthalate, triethylene glycol di-2-ethyl butyrate, acetyl tri-n-butyl citrate, amyl salicylate, benzyl benzoate, butoxyethyl stearate, "Cellosolve" laurate, oleate, ricinoleate or stearate, methyl "Cellosolve" stearate; glycerol mono-oleate, tricresyl phosphate, tetrabutyl urea, or di-n-butyl lauramide. Dioctyl phthalate and triethylene glycol di-2-ethyl butyrate are preferred. The propyl alcohols, particularly isopropyl alcohol, are the preferred alcoholic components of the solvent, and if a butyl alcohol is also used the propyl alcohol preferably constitutes at least half of the mixture by weight. The propyl acetates, particularly n-propylacetate, are the preferred ester components of the solvent, and if butyl acetate is also present should make up at least half the mixture by weight. The composition may comprise 3.5-5 per cent (particularly 4-4.8) by weight of nitrocellulose, 1.5-3 (particularly 2-2.8) of plasticizer, 5-25 (particularly 8-15) of octyl acetate, 5-25 (particularly 8-15) of alcohol and 50-80 (particularly 70-75) of the volatile ester. In an example a drop of a composition consisting of 5 parts by weight of nitrocellulose, 3 of dioctyl phthalate, 8.7 of octyl acetate (2-ethyl hexyl acetate), 12 of isopropyl alcohol and 80.8 of n-propyl acetate is allowed to spread for about 30 seconds to form a thin film over the surface of an aqueous phosphor-suspending medium contained in a television bulb (see Group XL (a)). A list of additional examples of film-forming compositions according to the invention is also furnished.