Coated sodium percarbonate particles comprising a sodium percarbonate core and a coating layer substantially free from sulphate, borate and magnesium compounds, process for their preparation

摘要

Coated sodium percarbonate particles containing a sodium percarbonate core and a coating layer substantially free from sulphate, borate and magnesium compounds. The coating layer comprises at least 30% and at most 70% w/w of an alkali metal carbonate and at least 25% and at most 70% w/w of an alkali metal silicate. The coating layer is obtained by using the alkali metal carbonate and silicate in the form of a coating solution to obtain a uniform dispersion of the alkali metal carbonate and the alkali metal silicate in the coating layer. The particles are prepared by mixing the alkali metal carbonate solution and the alkali metal silicate solution with the uncoated sodium percarbonate particles in a mixer operated at a temperature from room temperature to 50oC. This distributes the coating solution on the surface of the particles to obtain wet coated particles. The wet coated particles are removed form the mixer and dried in a fluid bed dryer using a stream of hot air of a temperature from 50 to 90oC to obtain dry coated particles. The coated sodium percarbonate particles may be used as an active bleach constituent and either a zeolitic or non-zeolitic builder in detergent compositions.