an improvement is proposed for an acrylic rubber composition to decrease the stickiness of the rubber composition under processing and shaped and vulcanized articles of the composition to a metallic surface with which the rubber article is kept in contact at an elevated temperature under compression as is the case in packings , gaskets and o - rings as automobile parts . the improvement can be obtained by compounding the rubber composition consisting of an acrylic rubbery polymer , which can be substituted by organosilicon groups , and a reinforcing filler with a limited amount of a specific diorganopolysiloxane , e . g ., dimethyl polysiloxane , of which from 5 to 50 % in number of the organic groups bonded to the silicon atoms are phenyl groups .