Method for improving flowability of heterophasic polypropylene powder

Method for the preparation of a sticky high impact heterophasic polypropylene (HECO) in a reactor facility comprising in series (i) a first reaction system, (ii) a first conveying line connecting the first reactor system with a second reactor system comprising an outlet, (iii) a second conveying line connecting the outlet with a purge bin comprising a feeder, and (iv) a conveying system being connected with the feeder, and the preparation of said heterophasic polypropylene (HECO) comprises the steps in the order of (a) producing in said first reactor system the polypropylene matrix (M), (b) transferring at least a part of said polypropylene to said second reactor system via the first conveying line, (c) producing in said second reactor system the elastomeric copolymer obtaining the heterophasic polypropylene (HECO), (d) discharging said heterophasic polypropylene (HECO) from said second reactor system via the outlet, (e) transferring said discharged heterophasic polypropylene (HECO) via the second conveying line to said purge bin comprising said feeder, and (f) transferring further said discharged heterophasic polypropylene (HECO) from said purge bin via said feeder to said conveying system, the produced heterophasic polypropylene (HECO) is provided with an additive, said additive is fed to the produced heterophasic polypropylene (α) at the outlet of the second reactor system, or ( ) at the feeder (F) of the purge bin (PB).