GB601651A - Improvements in potassium soap - Google Patents

Abstract

Potassium soaps, particularly those in which more than two-thirds of the fatty acids present are combined with potassium (commercially termed "potash soaps") are manufactured by saponifying triglycerides, fatty acids, or a mixture thereof, with an aqueous solution of potassium hydroxide free from potassium carbonate and keeping the product obtained for some hours at a temperature near to and below its boiling point, if desired, under superatmospheric pressure. Any potassium carbonate originally present in the potassium hydroxide may be removed by the addition of free fatty acids, after the first stage of saponification and the proportion of potassium hydroxide used may be less than that required for complete saponification. At least one partial fatty acid ester of a polyvalent aliphatic alcohol, e.g. of glycerol, polyglycerol, ethane diol or butanetetrol may be incorporated in the product obtained by saponification. The ester may be added as such, e.g. ethane diol monolaurate or butanetetrol monolaurate, or may be formed in situ by partial saponification of a triglyceride. In an example, 37 kg. of coconut oil was saponified with 18 kg. of carbonate-free 50 per cent potash lye and 44 kg. water. The product was maintained for some hours just below the boiling point and the water content adjusted so that the molten material immediately solidified when cooled to 30-35 DEG C. About 100 kg. of neutral soap were obtained which on the addition of about 10 per cent of water was converted into a thin liquid soap. The presence of partial esters renders the solid soap more unctuous. The absence of free potassium hydroxide or carbonate from the soaps is said to enable them to retain their initial homogeneous structure on prolonged storage.