GB693798A - Improvements in or relating to mould release agents for rubber - Google Patents

Abstract

A mould release agent for rubber consists of an emulsion comprising (by weight) from 10 to 35 per cent of a liquid dimethylpolysiloxane, from 2 to 5 per cent of an emulsifying agent, other than an alkali metal salt of a sulphated fatty alcohol, from 10 to 50 per cent of a polyethylene glycol, from 5 to 30 per cent of an alkali metal salt of a sulphated fatty alcohol, from 10 to 25 per cent of a powdered siliceous material, and from 15 to 23 per cent of water. The dimethylpolysiloxane used may contain trimethyl- and monomethyl-siloxane units. Emulsifying agents specified are morpholine salts of fatty acids containing 12 to 18 carbon atoms, e.g. morpholine-oleate and stearate; acetates of n-primary amines having 12 to 18 carbon atoms in the hydrocarbon chain, e.g. n-dodecyl-, n-octadodecenyl-, and n-octadecadienyl-amine acetates; mono-esters of polyethylene glycols and fatty acids containing 12 to 18 carbon atoms, e.g. hexaethylene glycol monooleate; alkylated aryl polyether alcohols, e.g. octyl-phenoxy polyethylene glycol, and thioalkyl ethers of polyethylene alcohols, e.g. polyethylene glycol tertiary dodecyl thio-ether. Polyethylene glycols specified are di-, tri- and hexa-ethylene glycols. Sulphated fatty alcohols specified are sodium lauryl sulphate, potassium octyl sulphate, sodium stearyl-sulphate and sodium octadecyl sulphate. Siliceous materials specified are bentonite, diatomaceous earth, fume silica, silica aerogels, clay and powdered quartz. Rust inhibitors, e.g. sodium nitrite, may be added to the compositions, which may be diluted with as much as 50 parts of water per part of the composition.