Rubber vulcanizates having excellent oil resistance, heat re­sistance and cold resistance can be obtained from a rubbery copoly­mer which is a polymerization product of an acrylic monomer mix­ture of which the essential components are an organosiloxy-con­taining acrylate compound such as acryloxymethyl pentamethyl disiloxane and 3-acryloxypropyl pentamethyl disiloxane and an epoxy group- or halogen-containing monomer such as allyl glyci­dyl ether, glycidyl methacrylate or vinyl chloroacetate, optional­ly with addition of an acrylate ester monomer such as ethyl acry­late, n-butyl acrylate or 2-methoxyethyl acrylate.