Abstract: Polycarbonate oligomer having uniform qualities is prepared by reacting an aqueous alkaline solution of 2,2-(4,4'-dihydroxydiphenyl) propane with phosgene in the presence of methylene chloride and as a characteristic point of this method, in the presence of an inert gas in an amount of 1 to 10 mol % based upon the phosgene.

Abstract: In the method for producing a high impact polystyrene from a monomer of styrene or/and its derivative and a rubbery polymer as reactants, an improvement is provided which comprises passing said reactants through a tubular reactor having parts where the passage way of flow of said reactants is constricted, while keeping said reactants in a laminar flow as much as possible in the parts other than said parts, in a first stage polymerization to prepare a reacted mixture containing a prepolymer until the conversion of monomer to polymer becomes 10 to 60%, and subjecting the resulting reacted mixture to a second stage polymerization in the state where almost no shearing is exerted thereupon.The shearing during said first stage polymerization can be uniformly carried out.The resulting product has superior high impact properties.

Abstract: A method of producing polycarbonate powder comprises continuously mixing and kneading a polycarbonate solution while heating same, the kneading being accomplished by producing a limited "to and fro" movement of the polycarbonate solution with the aid of a set of spiral blades mounted on rotating shafts in an elongated barrel.