Method for manufacturing ethylene-vinyl acetate copolymer and apparatus for manufacturing the same

A method for the continuous manufacture of an ethylene-vinyl acetate copolymer containing 5 mol % to 60 mol % of ethylene, the method comprising:

• (a′) continuously introducing ethylene, a vinyl acetate containing liquid, a polymerization solvent and a polymerization initiator into a polymerization vessel,
• whereby to form a polymerization solution,
• wherein at least a portion of the liquid is introduced via a heat exchanger,
• wherein the vinyl acetate liquid is either one selected from vinyl acetate and a vinyl acetate solution;
• (b′) continuously introducing an ethylene containing gas comprising ethylene vaporized from the polymerization solution into the heat exchanger;
• (c′) continuously bringing said gas into contact with said liquid in the heat exchanger so as to dissolve at least a portion of the ethylene in said gas into said liquid;
• wherein said gas and said liquid flow in parallel with each other in the heat exchanger,
• (d′) continuously introducing said liquid from the heat exchanger into the polymerization solution;
• (e′) continuously vaporizing a portion of the ethylene in the polymerization solution whereby to absorb at least a portion of the heat of polymerization in the polymerization solution,
• wherein said gas in step (b′) includes at least a portion of the ethylene vaporized in step (e′);
• and
• (f′) continuously draining a portion of the polymerization solution from the vessel.

An apparatus for the manufacture of an ethylene-vinyl acetate copolymer, comprising:

• a vessel for containing a polymerization solution that includes ethylene, vinyl acetate, a polymerization solvent and a polymerization initiator;
• a heat exchanger;
• a first pipe for introducing a vinyl acetate containing liquid into the heat exchanger, the first pipe having one end that is connected to the heat exchanger;
• a second pipe for introducing an ethylene containing gas from the vessel into the heat exchanger, the second pipe having one end that is connected to the heat exchanger;
• and
• a third pipe for introducing the vinyl acetate containing liquid from the heat exchanger into the vessel,
• wherein said one end of said first pipe and said one end of said second pipe are connected to the heat exchanger such that in use said gas and said liquid flow in parallel with each other in said heat exchanger.