A process for producing copolymers of ethylene and at least one alpha-olefin having from 4 to 10 carbon atoms in the presence of a solid Ziegler-Natta catalyst comprising of magnesium, titanium, halogen and an internal organic compound, the copolymer having a density of from 906 to 937 kg/m.sup.3 and a melt flow rate MFR.sub.21 measured at 190 C. under 21.6 kg load of from 3 to 150 g/10 min. The process includes the steps of (A) homopolymerising ethylene or copolymerising ethylene and a first alpha-olefin having from 4 to 10 carbon atoms in a first polymerisation stage in the presence of the polymerisation catalyst, hydrogen and optionally the first alpha-olefin; (B) copolymerising ethylene and a second alpha-olefin having from 4 to 10 carbon atoms in a second polymerisation stage in the presence of the first homo- or copolymer of ethylene and the Ziegler-Natta catalyst; and (C) recovering the polymer mixture.

A continuous solution polymerization process is disclosed wherein at least two catalyst formulations are employed. A first homogeneous catalyst formulation is employed in a first reactor to produce a first ethylene interpolymer and a first heterogeneous catalyst formulation is employed in a second reactor to produce a second ethylene interpolymer. Optionally a third ethylene interpolymer is formed in a third reactor. The resulting ethylene interpolymer products possess desirable properties in a variety of end use applications, for example in film applications. A means for increasing the molecular weight of the first ethylene interpolymer is disclosed and/or a means for increasing the temperature of the first reactor, relative to a third homogeneous catalyst formulation. A means for reducing the (-olefin/ethylene) weight ratio in the first reactor is disclosed and/or reducing the density of the first ethylene interpolymer, relative to a third homogeneous catalyst formulation.

The invention relates to a process for transitioning from a first continuous polymerization reaction in a reactor, for example a gas-phase reactor conducted in the presence of a first catalyst to a second continuous polymerization reaction in the reactor conducted in the presence of a second catalyst, wherein the first and second catalysts are incompatible, the process comprising: (a) discontinuing the introduction of the first catalyst from a catalyst feeding system into a reactor and emptying the catalyst feeding system of the first catalyst; (b) introducing a first catalyst killer to the reactor to substantially deactivate the first catalyst in the reactor; (c) introducing a second catalyst killer to the catalyst feeding system to substantially deactivate the first catalyst in the catalyst feeding system; (d) introducing a second catalyst to the catalyst feeding system and (e) introducing the second catalyst to the reactor from the catalyst feeding system, wherein the second catalyst killer is the same as or different from the first catalyst killer.

A process for the offline deactivation of at least one single site catalyst comprising contacting said catalyst with a deactivating agent selected from an aprotic low molecular weight carbonyl group containing organic compound or an aprotic low molecular weight orthoester or an aprotic low molecular weight acetal compound.

This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as amorphous silica, as quenching agents, typically in solution or bulk polymerization processes.

A polyethylene composition has a density of ?0.945 g/cm.sup.3, a melt index. I.sub.2 of from 0.8 to 4.0 g/10 min. an environmental stress crack resistance, an ESCR of greater than 400 hours as determined by ASTM D1693 in 100% IGEPAL CO-630 under conditions A or B. and a melt strength of ?3.0 cN.

Catalyst deactivating agents and compositions containing catalyst deactivating agents are disclosed. These catalyst deactivating agents can be used in methods of controlling polymerization reactions, methods of terminating polymerization reactions, methods of operating polymerization reactors, and methods of transitioning between catalyst systems.

Processes for transitioning from a first catalyst to a second catalyst in a gas phase polymerization reactor. In some embodiments, the processes relate to transitioning from a metallocene catalyst to a Ziegler-Natta catalyst. In other embodiments, the processes relate to transitioning from a first Ziegler-Natta catalyst to a second Ziegler-Natta catalyst.

Catalyst deactivating agents and compositions containing catalyst deactivating agents are disclosed. These catalyst deactivating agents can be used in methods of controlling polymerization reactions, methods of terminating polymerization reactions, methods of operating polymerization reactors, and methods of transitioning between catalyst systems.

A process for producing copolymers of ethylene and at least one alpha-olefin having from 4 to 10 carbon atoms in the presence of a solid Ziegler-Natta catalyst comprising of magnesium, titanium, halogen and an internal organic compound, the copolymer having a density of from 906 to 937 kg/m.sup.3 and a melt flow rate MFR.sub.21 measured at 190? C. under 21.6 kg load of from 3 to 150 g/10 min. The process includes the steps of (A) homopolymerising ethylene or copolymerising ethylene and a first alpha-olefin having from 4 to 10 carbon atoms in a first polymerisation stage in the presence of the polymerisation catalyst, hydrogen and optionally the first alpha-olefin; (B) copolymerising ethylene and a second alpha-olefin having from 4 to 10 carbon atoms in a second polymerisation stage in the presence of the first homo- or copolymer of ethylene and the Ziegler-Natta catalyst; and (C) recovering the polymer mixture.