| 摘要 |
1338280 Polymerizing ethylene SNAM PROGETTI SpA 22 June 1971 [23 June 1970] 29290/71 Heading C3P Polyethylene is polymerized at elevated pressure in a tubular reactor by a process which comprises (1) expanding the reaction mixture from a first expansion valve, (2) separating the expanded mixture in a high pressure separator into ethylene and a concentrated mixture of polyethylene and ethylene, (3) expanding said concentrated mixture in a second expansion valve, (4) separating the expanded mixture from (3) in a low pressure separator into polyethylene and the remaining unreacted ethylene, (5) withdrawing polyethylene from the low pressure separator, (6) mixing ethylene separated in (4) with fresh ethylene and compressing the mixture in a first compressor, (7) introducing the compressed mixture into the mixture (1) from the first expansion valve, (8) compressing in a second compressor the ethylene separated in (2), and (9) introducing the compressed ethylene from (8) into the reactor. The separated ethylene may be cooled, and low molecular weight polymers removed, before compression. Polymerization may be effected using oxygen, an organic peroxide or azo compound as catalyst, optionally in the presence of chain transfer agents, e.g. propane, butane, propylene or butene, or comonomers, e.g. vinyl acetate or vinyl acrylate; and pressure pulses may be imparted to the reaction mixture. Apparatus suitable for carrying out the process of the invention is described and illustrated, and in Example (2) ethylene is polymerized in the presence of oxygen, decanoyl peroxide and propylene. |
