Process for manufacturing granular coated sodium percarbonate for detergent

A process for the manufacture of granular coated sodium percarbonate comprising:

• (a) forming an intermediate granular coated sodium percarbonate by spraying the surface of a granular uncoated sodium percarbonate with a first mixed coating solution comprising alkali metal silicate and at least one compound chosen from sulfate, carbonate, and bicarbonate of alkali metals, wherein the molar ratio of SiO2/M2O in said alkali metal silicate ranges from about 3.2 to 3.5;
• (b) spraying of the surface of said intermediate coated sodium percarbonate with a second mixed coating solution comprising alkali metal sulfate and at least one compound chosen from carbonate and bicarbonate of alkali metals, wherein an outermost mixed coating solution does not comprise magnesium sulfate.

A process for the manufacture of granular coated sodium percarbonate comprising:

• (a) forming granular uncoated sodium percarbonate by continuously charging and stirring in a reactor anhydrous sodium carbonate, spraying hydrogen peroxide, and introducing cold air, wherein the uncoated sodium percarbonate is formed at 20-50° C. and 5-20% water content;
• (b) forming an intermediate granular coated sodium percarbonate by spraying the surface of said uncoated sodium percarbonate with a first mixed coating solution comprising alkali metal silicate and at least one compound chosen from sulfate, carbonate, and bicarbonate of alkali metals, wherein the molar ratio of SiO2/M2O in said alkali metal silicate ranges from about 3.2 to 3.5,
• (c) spraying of the surface of said intermediate coated sodium percarbonate with a second mixed coating solution comprising alkali metal sulfate and at least one compound chosen from carbonate and bicarbonate of alkali metals, wherein at least one of said mixed coating solutions further comprises at least one surfactant.