Abstract: 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.

Abstract: 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.

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.

Abstract: Copolymers of ethylene containing not more than 4 moles, based on 100 moles of ethylene, of copolymerized C.sub.3 -C.sub.6 -alkenecarboxylic acids are prepared in a continuously operated tubular polymerization system under high pressures and temperatures in the presence of a polymerization initiator by a process in which a mixture of ethylene, the alkenecarboxylic acid, if required a further monomer which is copolymerizable with ethylene, an initiator and, if required, a regulator is fed into the polymerization system at its entrance and at the same time at a second point downstream of the entrance, along the polymerization system, where the reaction temperature has exceeded a maximum, the amount of alkenecarboxylic acid at the entrance of the polymerization system being not more than 0.3, preferably less than 0.28, mole, based on 100 moles of ethylene, and the remainder being metered in at the second feed point.

Abstract: A process for the continuous production of an ethylene copolymer by compressing a mixture of ethylene and comonomer in a pre-compressor and a post-compressor, copolymerizing the mixture in a polymerization zone at a high temperature and high pressure, transferring the reaction mixture into a high pressure product isolation zone, from there into a low pressure product isolation zone and thereafter into a discharge extruder, and recycling the greater part of the unconverted monomer into the polymerization process and passing a small part of the unconverted gas into a low temperature isolation zone, in which process a small part of the gas recycled from the high pressure product isolation zone is passed into the low temperature isolation zone, which is preferably under a pressure of from 10 to 30 bar and at from -10.degree. to -50.degree. C., and all the gas taken off the low pressure product isolation zone is fed to the pre-compressor.

Abstract: A continuous process for the manufacture of ethylene copolymers under high pressure and at high temperature in a polymerization zone, with transfer of the reaction mixture into a high pressure product isolation zone and from there into a low pressure product isolation zone, and recycling of the unconverted gas from the high pressure product isolation zone into the polymerization zone and from the low pressure product isolation zone into a low temperature separator, from where the comonomer separated off is recycled to the polymerization process, while the ethylene is discharged as off-gas. The gas taken off the low pressure product isolation zone is preferably compressed to from 10 to 20 bar and cooled to from -10.degree. to -30.degree. C. before it is fed into the low temperature separator. There is a substantial improvement in the efficiency of separating off the comonomer.

Abstract: A process for the manufacture of ethylene polymers by polymerizing ethylene under high pressures and at high temperatures in the presence of from 0.01 to 0.5 percent by weight of an alkyl ester (alkyl being of 1 to 8 carbon atoms) of an alkenemonocarboxylic acid of 3 or 4 carbon atoms. n-Butyl acrylate is a particularly suitable polymerization activator. Although the start temperature of the ethylene polymerization is relatively low, there is no difference in mechanical and optical properties of a blown film manufactured from the resulting ethylene polymer and of a blown film of pure polyethylene.

Abstract: A process for the manufacture of copolymers of ethylene with tert-butyl acrylate and acrylic acid at from 200.degree. to 350.degree. C under pressures above 800 atmospheres using mean residence times of up to at most 100 seconds, in which the reaction mixture obtained from the polymerization is kept for from 2 to 10 minutes at from 200.degree. to 250.degree. C under a pressure of not more than 500 atmospheres. Terpolymers are obtained which may be used as hot-melt adhesives in the form of thin and extremely homogeneous films.

Abstract: A process for the manufacture of copolymers of ethylene with n-butyl acrylate in a polymerization zone at pressures above 800 atmospheres and at from 150.degree. to 350.degree. C, wherein the reaction mixture obtained is transferred, via a cooling zone which is at a pressure below 500 atmospheres and at from 150.degree. to 250.degree. C, into the high pressure product isolation zone, the mean residence time of the reaction mixture in the two zones being from 2 to 10 minutes. A copolymer which gives good films is obtained.

Abstract: A process for the manufacture of copolymers of ethylene with vinyl acetate at pressures above 800 atmospheres and at from 150.degree. to 350.degree. C, using mean residence times of up to at most 100 seconds. The reaction mixture obtained from the polymerization is kept for from 2 to 10 minutes at from 150.degree. to 250.degree. C under a pressure below 500 atmospheres. Homogeneous ethylene/vinyl acetate copolymers are obtained without the formation of substantial amounts of free acetic acid by decomposition of the vinyl acetate.