GB797971A - Organosiloxane compositions - Google Patents

Abstract

Compositions which are suitable as mould release agents, particularly in the moulding of glass, comprise an aqueous emulsion of a liquid polysiloxane having an R/Si ratio of 1.9 to 3, one or more emulsifying agents, and 0.01 to 10 per cent of graphite. The preferred proportions are 1 to 75 per cent siloxane, 0.1 to 6 per cent emulsifying agent, and 20 to 98 per cent water. If desired, up to 20 per cent of finely divided silica such as diatomaceous earth, aerogel or fumed silica, and up to 5 per cent of a clay thickener such as Bentonite may be added. The compositions may first be prepared in concentrated form and diluted before using. The organic radicals in the siloxane may be alkyl, alkenyl and aryl and they may be halogenated. The polymers can contain mono-, di- or tri-organosiloxane units. The preferred materials are trimethylsiloxy end-blocked - dimethylpolysiloxane, -phenylmethylsiloxane or -phenylmethylsiloxane - dimethylsiloxane copolymers. Suitable emulsifying agents are morpholine salts of fatty acids having 12 to 18 carbon atoms in the acid chain, e.g., the oleate or stearate; acetates of n-primary amines of 12 to 18 carbon atoms, e.g., of n-dodecyl, n-octadecyl or n-octadecenyl amine; mono-esters of polyethylene glycols and C12-18 fatty acids, e.g. hexaethylene glycol monooleate; alkylated aryl polyether alcohols; and alkali metal salts of alkylated aryl polyether sulphates. The emulsifying agent may be formed in situ. The graphite may be used in the form of a colloidal suspension in water or other solvents.ALSO:A mould lubricant comprises an aqueous emulsion of a liquid organo polysiloxane, one or more emulsifying agents and for 0,01 to 10 per cent of graphite. Other materials such as finely divided silica or clay thickeners may be included.