The invention relates to a process for the preparation of a thixotropic composition comprising polyurea particles, said process comprising contacting and reacting in a liquid medium reactants 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. The invention further relates to a thixotropic composition obtainable by the process, in particular thixotropic composition comprising high amounts of polyurea particles and optionally a polymer resin having high thixotropic efficiency. The compositions can be used, in particular as a masterbatch, in preparation of i.a. coating compositions.

A thixotropic agent for increasing the yield point of a curable composition, wherein the thixotropic agent includes (i) at least one urea compound from the reaction of at least one isocyanate with at least one amine and (ii) at least one polyether having blocked hydroxyl groups. The thixotropic agent is preparable in a simple manner and forms a spreadable paste which is firm at room temperature. It is particularly suitable as a constituent of moisture-curing polyurethane or SMP compositions, giving a good increase in the yield point thereof, without adversely affecting storage stability or migration characteristics. It enables phthalate-free adhesives, sealants or coatings that have surprisingly good conveyability coupled with a high yield point, and do not cause any problems with odor or fogging.

The invention relates to a process for the preparation of a thixotropic composition comprising polyurea particles, said process comprising contacting and reacting in a liquid medium reactants 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. The invention further relates to a thixotropic composition obtainable by the process, in particular thixotropic composition comprising high amounts of polyurea particles and optionally a polymer resin having high thixotropic efficiency. The compositions can be used, in particular as a masterbatch, in preparation of i.a. coating compositions.

A thixotropic agent for increasing the yield point of a curable composition, wherein the thixotropic agent includes (i) at least one urea compound from the reaction of at least one isocyanate with at least one amine and (ii) at least one polyether having blocked hydroxyl groups. The thixotropic agent is preparable in a simple manner and forms a spreadable paste which is firm at room temperature. It is particularly suitable as a constituent of moisture-curing polyurethane or SMP compositions, giving a good increase in the yield point thereof, without adversely affecting storage stability or migration characteristics. It enables phthalate-free adhesives, sealants or coatings that have surprisingly good conveyability coupled with a high yield point, and do not cause any problems with odor or fogging.