Processes for preparing a powdery high rubber impact modifier containing
two or more populations of polymer particles having a total rubbery weight fraction
of greater than 90 weight percent is provided. Also provided are various methods
of preparing aqueous polymer particle dispersions having two or more populations
of polymer particles having a total rubbery weight fraction of greater than 90
weight percent. These dispersions are spray-driable into a powder and are useful
for increasing the impact strength of various matrix resins.
