Patent ID: 7745550

Claim:
A polymerization process in a tubular reactor comprising: a. compressing a monomer feed having a chain transfer agent concentration of less than 0.1 mol %; b. polymerizing the compressed monomer feed of step (a) in a reactor tube to form a polymer-monomer mixture, wherein the reactor tube has at least a first, second, and third reaction zones spaced lengthwise along the reactor tube and wherein the reactor tube comprises: i. multiple monomer feed injection positions spaced lengthwise along the reactor tube; ii. multiple chain transfer agent stream injection positions spaced lengthwise along the reactor tube; and iii. multiple free-radical initiator injection positions spaced lengthwise along the reactor tube; c. compressing a chain transfer agent to form at least one compressed chain transfer agent stream, wherein the chain transfer agent is compressed separately from the monomer feed; d. blending the compressed chain transfer agent stream of step (c) with varying amounts of compressed monomer feed having a chain transfer agent concentration of less than 0.1 mol % to form a first, second, and third chain transfer agent-rich stream having different chain transfer agent concentrations, wherein i. the first chain transfer agent-rich stream has a chain transfer agent concentration that is at least 60% higher than the chain transfer agent concentration of the second chain transfer agent-rich stream; and ii. the second chain transfer agent-rich stream has a chain transfer agent concentration that is at least 100% higher than the chain transfer agent concentration of the third chain transfer agent-rich stream; e. introducing at least one compressed chain transfer agent-rich stream of step (d) into each of the first, second, and third reaction zones to modify the molecular weight of the polymer, wherein i. the first chain transfer agent-rich stream is introduced to the first reaction zone upstream of the second reaction zone which receives the second chain transfer agent-rich stream; and ii. the second chain transfer agent-rich stream is introduced to the second reaction zone upstream of the third reaction zone receiving the third chain transfer agent-rich stream; and f. separating the polymer-monomer mixture received from the reactor tube into a volatile monomer-rich phase and a molten polymer phase.