The present invention relates to a multi-stage process for producing a C.sub.2 to C.sub.8 olefin polymer composition in a process comprising at least two reactors, wherein a pre-polymerized solid Ziegler-Natta catalyst is prepared by carrying out an off-line pre-polymerization of a solid Ziegler-Natta catalyst component with a C.sub.2 to C.sub.4 olefin monomer before feeding to the polymerization process.

The present invention relates to a multi-stage process for producing a C.sub.2 to C.sub.8 olefin polymer composition in a process comprising at least two reactors, wherein a pre-polymerized solid Ziegler-Natta catalyst is prepared by carrying out an off-line pre-polymerization of a solid Ziegler-Natta catalyst component with a C.sub.2 to C.sub.4 olefin monomer before feeding to the polymerization process.

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.

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.

An improved solid Ziegler-Natta type catalyst for the (co)polymerisation of ethylene and -olefins, particularly in high-temperature processes, such as for example adiabatic solution processes and high-pressure adiabatic processes with elevated productivity, is provided. Said catalyst is obtained by means of an original process comprising dissolving in hydrocarbons, compounds of titanium, magnesium and optionally a metal selected from hafnium and zirconium, and reprecipitating them in two steps in succession, the first of which is chlorination and the second reduction.

An improved solid Ziegler-Natta type catalyst for the (co)polymerisation of ethylene and -olefins, particularly in high-temperature processes, such as for example adiabatic solution processes and high-pressure adiabatic processes with elevated productivity, is provided. Said catalyst is obtained by means of an original process comprising dissolving in hydrocarbons, compounds of titanium, magnesium and optionally a metal selected from hafnium and zirconium, and reprecipitating them in two steps in succession, the first of which is chlorination and the second reduction.

Mono- and multi-layer films comprising a polyethylene composition which comprises the reaction product of ethylene and optionally one or more alpha olefin comonomers in the presence of a catalyst composition comprising a multi-metallic procatalyst via a solution polymerization process in at least one reactor; wherein said polyethylene composition is characterized by one or more of the following properties: a melt index, I.sub.2, measured according to ASTM D 1238 (2.16 kg @ 190 C.), from 0.1 to 5 g/10 min; density, measured according to ASTM D-792, from 0.910 to 0.935 g/cc; melt flow ratio, I.sub.10/I.sub.2, wherein I.sub.10 is measured according to ASTM D1238 (10 kg @ 190 C.), from 6 to 7.4; and molecular weight distribution, (M.sub.w/M.sub.n) from 2.5 to 3.5 are provided. Also provided are articles made from the mono- and/or multi-layer films.

Mono- and multi-layer films comprising a polyethylene composition which comprises the reaction product of ethylene and optionally one or more alpha olefin comonomers in the presence of a catalyst composition comprising a multi-metallic procatalyst via a solution polymerization process in at least one reactor; wherein said polyethylene composition is characterized by one or more of the following properties: a melt index, I.sub.2, measured according to ASTM D 1238 (2.16 kg @ 190 C.), from 0.1 to 5 g/10 min; density, measured according to ASTM D-792, from 0.910 to 0.935 g/cc; melt flow ratio, I.sub.10/I.sub.2, wherein I.sub.10 is measured according to ASTM D1238 (10 kg @ 190 C.), from 6 to 7.4; and molecular weight distribution, (M.sub.w/M.sub.n) from 2.5 to 3.5 are provided. Also provided are articles made from the mono- and/or multi-layer films.

Methods of forming a catalyst, catalysts, polymerization processes and polymers formed therefrom are described herein. The method of forming a catalyst generally includes contacting an alkyl magnesium compound with an alcohol to form a magnesium alkoxide compound; contacting the magnesium alkoxide compound with a first titanium alkoxide and a first agent to form a reaction product A, wherein the titanium alkoxide and the first agent are nonblended individual components prior to contacting the magnesium alkoxide; and sequentially contacting the reaction product A with a second agent, followed by a third agent, and subsequently a first reducing agent to form a catalyst component.

Methods of forming a catalyst, catalysts, polymerization processes and polymers formed therefrom are described herein. The method of forming a catalyst generally includes contacting an alkyl magnesium compound with an alcohol to form a magnesium alkoxide compound; contacting the magnesium alkoxide compound with a first titanium alkoxide and a first agent to form a reaction product A, wherein the titanium alkoxide and the first agent are nonblended individual components prior to contacting the magnesium alkoxide; and sequentially contacting the reaction product A with a second agent, followed by a third agent, and subsequently a first reducing agent to form a catalyst component.