GB806340A - Improved detergent compositions - Google Patents

Abstract

A process for improving the non-caking characteristics of a spray-dried granular detergent composition, which comprises at least one water-soluble anionic synthetic detergent of the sulphuric reaction product type and at least one hydratable alkali metal phosphate, consists in agitating the granules while simultaneously spraying them with an aqueous solution of magnesium, zinc or aluminium sulphate in an amount such that such sulphates, calculated as anhydrous sulphate, comprise 1-10 per cent, preferably 2-4 per cent, of the granules The water content of the granules is thereby raised to the amount of 12-25 per cent, and usually 14-17 per cent. The process yields a product, the granules of which have a coating of one or more hydrated double phosphates of the alkali metal with zinc, magnesium, or aluminium. The detergent used may be a sodium alkyl sulphate, but is preferably a sodium polypropylene benzene sulphonate averaging 12 carbon atoms in the polypropylene group, in an amount of 20-40 per cent by weight of the composition. The phosphate, which may be a tripoly-, pyro-, or orthophosphate or mixture thereof, is usually present to the extent of 10-60 per cent. The concentration of the inorganic sulphate solution applied to the granules is suitably 18-22 per cent. The final composition generally contains 10-30 per cent of sodium sulphate, together with minor amounts of carboxymethylcellulose, sodium silicate, coconut fatty acid ethanolamide, fluorescent dyes, colouring, and perfume. The inorganic sulphate solution may suitably be applied by spraying either simultaneously or sequentially with the addition of such adjuncts in conventional rotating mixing drums. Specification 614,044 is referred to.