Multi-stage process for producing a C2 to C8 olefin polymer composition

A continuous multi-stage process for producing a C2 to C8 olefin polymer composition in at least two reactors, the continuous multi-stage process comprising the steps of:

• a) introducing a stream of a pre-polymerized solid Ziegler-Natta catalyst and a monomer of C2 to C8 olefin into a first polymerization reactor, thereby producing in a first polymerization a first C2 to C8 olefin polymer;
• b) withdrawing a stream comprising the first C2 to C8 olefin polymer from the first polymerization reactor and passing it into a second polymerization reactor;
• c) introducing a stream of a monomer of C2 to C8 olefin into the second polymerization reactor, thereby producing in a second polymerization a first polymer mixture comprising the first C2 to C8 olefin polymer and a second C2 to C8 olefin polymer produced in the second polymerization reactor;
• and
• d) withdrawing a stream comprising the first polymer mixture from the second polymerization reactor, thereby obtaining the C2 to C8 olefin polymer composition;
• wherein the pre-polymerized solid Ziegler-Natta catalyst is prepared by off-line pre-polymerization of a solid Ziegler-Natta catalyst component with a C2 to C4 olefin monomer before feeding to the continuous multi-stage process, and wherein the pre-polymerized solid Ziegler-Natta catalyst has a particle size distribution span ((d90-d10)/d50) of below 1.5.