METHOD OF PREPARING COATED SODIUM CARBONATE PERHYDRATE STABLE IN DETERGENT COMPOSITIONS Russian patent published in 1998 - IPC

FIELD: detergents. SUBSTANCE: anhydrous sodium carbonate is spread throughout aqueous solution containing 50-75 wt % hydrogen peroxide and 0.5-3.5 wt % 1-hydroxyethylidene-1,1- diphosphonic acid at 50-80 C. All acid is added with first 20-50% of hydrogen peroxide to form sodium carbonate perhydrate containing 12- 14% of active oxygen and 0.5-10% of 1-hydroxyethylidene-1,1- diphosphonic acid. Product is suspended in gas flow with great number of droplets of sodium borosilicate aqueous solution 25-75 weight parts of sodium silicate and 75-25 weight parts of sodium metaborate at SiO₂/B₂O₃ and SiO₂/Na₂O weight ratios 1:(1-2) and 3:1, respectively. All water is distilled away to give coated sodium carbonate perhydrate with volume density 800-1050 kg/cu. m and containing 14 wt % active oxygen. All active oxygen releases into water for 2 min. EFFECT: improved procedure. 7 cl, 10 tbl, 9 ex