Nova Chemicals (international) S.a.

Fraser Waldie

Tony Tikuisis

P Scott Chisholm

Owen Lightbody

Derek Wasylenko

Norman Aubee

Douglas Checknita

In the manufacture of extruded polymers there are a number of surface defects referred to as sharkskin, snakeskin and orange peel which all generally relate to the rheology of the polymer melt. A severe form of surface defect is 'melt fracture' which is believed to result when the shear rate at the surface of the polymer is sufficiently high that the surface of the polymer begins to fracture. That is, there is a slippage of the surface of the extruded polymer relative to the body of the polymer melt. The surface generally can't flow fast enough to keep up with the body of the extrudate and a fracture in the melt occurs generally resulting in a severe loss of surface properties for the extrudate. A polymer extension process is disclosed wherein these undesirable surface defects are eliminated.

Polymer extrusion process

The present disclosure relates to systems including a ternary stabilization package that contains a first phosphite, a second phosphite and a primary antioxidant is used in combination with a polyethylene that is polymerized with a mixed catalyst system that contains two different types of catalysts. In some embodiments the stabilized polyethylene exhibits improved color performance.

Stabilization of mixed catalyst polyethylene

In some embodiments, this disclosure provides a process for the stabilization of thermoplastic polyolefins during melt processing operations. In some embodiments, the stabilizer package disclosed herein is 'phenol free' and contains at least one solid aryl monophosphite and a specific liquid phosphite. The processes disclosed herein are suitable for the manufacture of polyethylene film.

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Calgary, Canada

Fraser Waldie