Abstract: In a separation system (1 to 11) for tube reactors or autoclaves, which are used for the polymerization of ethylene or copolymerization of ethylene with ethylenically unsaturated comonomers in the presence of an initiator under from 500 to 4,000 bar and at from 150.degree. to 350.degree. C., for reducing the emission of solids during pressure relief processes of the reaction mixture present in the reactor or autoclave, the reaction mixture let down is fed via two or more separating containers (1, 1a) installed in series before it reaches the atmosphere.

Abstract: The pressure in a continuous high pressure polymerization system, in which ethylene, with or without comonomers, is polymerized under high pressures and temperatures and the unconverted amounts of gas are recycled through the high pressure recycle gas system into the polymerization system, is rapidly reduced to below the particular reaction pressure when predetermined limiting pressure and/or temperature values are exceeded or when other faults occur by opening one or more pressure-relief apparatuses mounted on the high pressure polymerization system and transferring the hot let-down reaction mixture from the polymerization system via one or more let-down lines through one or more separator systems into the atmosphere, by a process in which the high pressure polymerization system is divided into a plurality of isolated sections at the same time as the let-down process is triggered and only the section in which the let-down process is triggered is let down to the atmosphere.

Abstract: Copolymers of ethylene with vinyl esters are prepared in a continuously operated tubular polymerization system at high pressure and temperatures by feeding a mixture of ethylene, vinyl ester, initiator and, if appropriate, regulant into the polymerization system in the form of a mainstream at the inlet point thereof and at the same time through two or more secondary streams downstream of the inlet point, secondary streams (I) being metered in at points where the reaction temperature has just exceeded a maximum temperature due to the heat of polymerization and secondary streams (II) at points which, relative to the direction of flow of the ethylene, are upstream of the feed points of secondary streams (I) and upstream of the respective maximum temperature.

Abstract: Copolymers of ethylene with acrylates or solutions of free acrylic acid in acrylates are prepared in a continuously operated tubular polymerization system at high pressures and temperatures by feeding a mixture of ethylene, acrylate, initiator and, if appropriate, regulant into the polymerization system in the form of a main stream at the inlet point thereof and at the same time through two or more secondary streams, secondary streams (I) being metered in at points where the reaction temperature has just exceeded a maximum temperature due to the heat of polymerization and secondary streams (II) at points which, relative to the direction of flow of the ethylene, are upstream of the feed points of secondary streams (I) and upstream of the respective maximum temperature.