Basf Aktiengesellschaft

Gerhard Arnold

Klaus Pfleger

Siegfried Schiller

Herbert Mueller

Klaus Boettcher

Franz G Mietzner

Friedrich Kanne

Siegfried Kursawe

Copolymers of ethylene with acrylates or acrylic acid are prepared by copolymerizing 100 parts by weight of ethylene with from 1.0 to 20.0 parts by weight of tert-butyl acrylate or tert-butyl methacrylate or acrylic acid or solutions of acrylic acid in acrylates in a continuously operated, tubular polymerization system at above 800 bar and at from 130.degree. to 320.degree. C. in the presence of a free radical polymerization initiator by feeding two gas streams into the polymerization system, by a process in which the first gas stream contains exclusively ethylene with a polymerization initiator and, if required, a polymerization regulator and the second gas stream contains a mixture of ethylene and tert-butyl acrylate or tert-butyl methacrylate or a mixture of ethylene with a solution of acrylic acid in acrylates and polymerization initiators and, if required, polymerization regulators.

Preparation of copolymers of ethylene with acrylates or acrylic acid

A process for preparing copolymers of ethylene with acrylic esters by copolymerizing 100 parts by weight of ethylene with from 0.1 to 25.0 parts by weight of acrylic ester in a continuous tubular polymerization system at from 500 to 4000 bar and from 100.degree. to 400.degree. C. in the presence of free radical polymerization initiators, comprises controlling the temperature for the reaction mixture, comprising ethylene, the acrylic ester, the polymerization initiator and optionally a regulator, after entry into the reaction zone in such a way that the ratio dT/dt (temperature increase per unit time) is kept constant at a value within the range from 1.5.degree. to 2.5.degree. C. per second.

Preparation of copolymers of ethylene with acrylic esters

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. Preferably, the sections in which the let-down process is not triggered can be let down into the high pressure recycle gas system, if necessary through a product separator, in synchronization with triggering of the let-down to the atmosphere.

Reduction of the emission of hydrocarbons in pressure-reduction

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Wesseling, Germany

Gerhard Arnold