Process for manufacturing a detergent briquette

Readily disintegrable detergent briquettes are obtained by mixing together a normally solid water-soluble anionic synthetic detergent with a normally solid water-soluble inorganic salt to produce a particulate composition containing up to 21%, preferably 2-15%, moisture, moistening the particles with 4-12%, preferably 4-10%, added water to raise the moisture content to 4-25%, preferably to 8-19%, agglomerating the particles into a lightly compacted briquette at a pressure low enough to form a disintegrable briquette, e.g. 3-100 p.s.i., preferably 15-50 p.s.i., and then applying to the briquette 1-5% by weight of a water-soluble synthetic organic film-forming polymer, preferably a 10-25% aqueous solution of a polyvinyl alcohol having a weight average degree of polymerization of 30-300 and a polyvinyl acetate content of 10-30%, so as to form on the briquette surface a water-soluble film, preferably having an average thickness of 0.05-0.8 mm., having a strength sufficient to make the briquette resistant to breakage when dry but allowing ready solubility in water. Preferred compositions contain 20-40% of such detergents as sodium, potassium or magnesium alkyl sulphates, N-higher fatty acyl-N-methyl taurides, a -sulphonates of higher fatty acids, and n-higher alkyl sulphonates, sodium C12- 20 alkyl benzene sulphonates being especially favoured; 20-70% of the inorganic salt, e.g. sodium sulphate and chloride, potassiumsulphate, and particularly sodium tripolyphosphate and pyrophosphate; and 1-30% of various other adjuvants including sodium silicate (Na2O : SiO2 = 0.43). Film-forming polymers other than polyvinyl alcohol which may be used include polyvinylpyrrolidene, sodium carboxymethylcellulose and hydroxypropylmethylcellulose. the particulate composition which is to be pressed is suitably obtained by atomizing a slurry mixture into a drying gas to the required moisture content; after the additional water has been sprayed on to the tumbled particles, aggregates over 4 mm. diameter are removed leaving particles within the range 0.1-4 mm., and these are agglomerated to briquettes of a density of 0.4-0.7 g. per c.c.