Process and apparatus for preparation of vinyl polymers

Claim 1

In a process for the preparation of vinyl polymers by bulk or solution polymerization comprising continuously introducing a polymerization starting material containing at least one vinyl monomer, at least one polymerization initiator and at least one polymerization regulator into a polymerization reactor of the complete mixing type, polymerizing the monomer while mixing the contents of the polymerization reactor whereby a reaction mixture containing polymer is formed, keeping the temperature of the reaction mixture at a constant level between 100° and 200° C. by removing the heat of polymerization with cooling means provided inside or outside of the reactor, maintaining the polymer content of said reaction mixture at 50 to 80% by weight, withdrawing a stream of reaction mixture containing polymer from the polymerization reactor, introducing the reaction mixture withdrawn from the polymerization reactor into a separation zone where volatiles are separated from the reaction mixture, said separated volatiles being recycled to be used as a part of the monomer for the polymerization starting material, the improvement which comprises dividing said stream of reaction mixture into a first stream and a second stream, feeding said first stream to said separation zone, continuously mixing fresh polymerization starting material with said second stream and recycling the resulting mixture to said polymerization reactor through an opening located at a position corresponding to 1/4 or less of the total height from the bottom to the top of said reactor.