Process for producing ethylene homo- and copolymers

A process for producing an ethylene copolymer, comprising:

• a) compressing ethylene monomer in one or more compressors to a pressure equal to or greater than 120 MPa in order to obtain a compressed ethylene monomer;
• b) adding to the compressed ethylene monomer a fresh comonomer in liquid form at a pressure equal to or greater than 120 MPa in order to obtain a compressed ethylene/comonomer mixture;
• c) optionally, adding into the compressed ethylene/comonomer mixture a fresh modifier in liquid form at a pressure equal to or greater than 120 MPa in order to obtain a compressed reaction mixture;
• d) introducing the compressed ethylene/comonomer mixture, or the compressed reaction mixture into an autoclave reactor and, optionally, at least one additional reactor;
• e) adding into the autoclave reactor and, optionally, into the at least one additional reactor at least one free radical initiator in order to start a polymerization reaction;
• and
• f) separating an ethylene copolymer;
• wherein the autoclave reactor has a first reaction zone and at least one more reaction zone, and all the compressed ethylene/comonomer mixture, or all the compressed reaction mixture that is introduced in the autoclave reactor is introduced into the first reaction zone;
• wherein the autoclave reactor has a total reactor volume, and the first reaction zone has a volume that is greater than 50% of the total reactor volume;
• and
• wherein the compressed ethylene/comonomer or the compressed reaction mixture is introduced into the autoclave reactor and, optionally, into the at least one additional reactor at a temperature from −20° C. to 70° C.