Process for preparing microcapsules having a polyurea shell and a lipophilic core material

A process for preparing microcapsules, wherein the microcapsules have a volume average diameter d 50 of 15 to 90 μm and a percentage of the shell weight of 3 to 40%, with reference to the total weight of capsules, wherein a shell of the microcapsules comprises at least one polyurea and a core comprises at least one lipophilic component with the proviso that the core does not contain a fragrance, comprising the steps of:

• a) providing a premix (I) comprising at least one protective colloid different from a hydroxyalkylcellulose in an aqueous solution,
• b) providing a premix (II) comprising at least one polyisocyanate and at least one lipophilic component,
• c) mixing premix (I) and premix (II) until an emulsion (III) is formed,
• d) adding an aqueous solution (IV) containing at least one polyfunctional amine to the emulsion formed in step c),
• e) forming a dispersion of microcapsules by heating the mixture obtained in step d) to a temperature of at least 50° C. until microcapsules are formed, and
• f) adding the hydroxyalkylcellulose to the dispersion obtained in step e), wherein the amount of the hydroxyalkylcellulose is 0.01 to 1.2% by weight based on the total weight of the dispersion.