| abstract |
The invention relates to coated peroxygen compounds, in particular coated sodium percarbonate particles, with a delayed release of the active oxygen (=increased dissolving time). Particles according to the invention comprise an innermost shell layer, comprising at least one hydrate-forming inorganic salt, and an outer shell layer, comprising 0.2 to 3 wt. % alkali metal silicate with a modulus of greater than 2.5, in particular 3 to 5, the outer layer having been prepared using an alkali metal silicate solution with an alkali metal silicate concentration in the range from 2 to 20 wt. %. By lowering the alkali metal silicate concentration in the solution to be used, the dissolving time can be increased for the same shell amount. The dissolving time can be increased greatly by the layer sequence and the concentration of the solution, at a low amount of alkali metal silicate. |