Method for preparing microcapsules by double emulsion

Method for preparing solid microcapsules, comprising the steps of:

• a) adding under agitation a composition C1 comprising at least one active material to a cross-linkable liquid composition C2,
• wherein the active material is not an additive to be used in the lubricant, fuel or bitumen industries, or in drilling sludges or muds, or an additive to be used in oil exploration/production,
• composition C1 and composition C2 being immiscible with each other,
• so that a first emulsion is obtained, said first emulsion comprising droplets of composition C1 dispersed in composition C2,
• b) adding under agitation the first emulsion obtained in step a) to a liquid composition C3,
• composition C3 and composition C2 being immiscible with each other,
• so that a second emulsion is obtained, said second emulsion comprising droplets dispersed in composition C3,
• c) loading the second emulsion obtained in step b) in a mixer which applies a homogeneous controlled shear rate to said second emulsion, said shear rate being from 2 000 s−1 to 100 000 s−1,
• so that a third emulsion is obtained, said third emulsion comprising droplets dispersed in composition C3, and
• d) cross-linking the droplets obtained in step c),
• so that solid microcapsules dispersed in composition C3 are obtained, wherein said method is carried out in the absence of surfactant and/or emulsifier.