Process for the preparation of a thixotropic composition

A process for the preparation of a thixotropic composition comprising polyurea particles, said process comprising:

• contacting and reacting in a liquid medium, reactants (I) comprising a polyisocyanate (a) and a mono-amine (b), or reactants (II) comprising a polyamine (a) and a mono-isocyanate (b) to form a polyurea, and
• precipitating the polyurea to form polyurea particles, wherein acoustic vibration is applied during contacting of the reactants or as a post-treatment on the formed polyurea particles or both,
• wherein the reaction takes place in the liquid medium in substantial absence of a polymeric resin material, and the thixotropic composition comprises at least 4 wt % of the polyurea particles relative to the total weight of the thixotropic composition and substantially no polymeric resin material;
• or
• wherein the polyurea particles are formed in the presence of the polymeric resin material, and the thixotropic composition comprises between 1 and 40 wt % of the polymeric resin material and at least 4 wt % of the polyurea particles relative to the total weight of the thixotropic composition including the polymeric resin material;
• or
• wherein the reaction takes place in a resin composition comprising between 40 wt % and 85 wt % of the polymeric resin material as a binder, and the thixotropic composition comprises between 0.1 and 8 wt % of the polyurea particles, wherein the wt % are relative to the total weight of the thixotropic composition.