Coperion Werner & Pfleiderer : Compounding Oil Pipe with 50% Microspheres
Coperion Werner & Pfleiderer in Germany has applied for a patent on a novel process for compounding and direct extrusion of plastic filled with hollow particles. The compound is a heat-insulating syntactic foam containing 50% by volume (30% by weight) glass microspheres. It is used as a mid layer in a steel/polypropylene composite pipe for undersea oil transport. Scotchlite microspheres from 3M range in size from 10 to 120 microns with 50% of them less than 40 microns and 90% less than 80 microns.
The trick is not to crush them during mixing. Coperion says its ZSK MegaVolume kneader, which has an unusually high free volume in the screw, can blend the microspheres into melted PP with minimal breakage. Microspheres are added about halfway down the barrel with a twin-screw side feeder. High free volume in the screw also folds more air into the melt, so the machine has a special degassing vent to keep melt from escaping.
The eight-layer pipe was developed for Bredero Shaw Norway AS in Orkanger, Norway. It includes both conventional and syntactic foams separated by a solid PP layer, as well as a solid PP outer skin, and adhesively modified PP next to the steel inner core. The entire process line is installed in two air-conditioned, 40-ft shipping containers for mobile production of undersea pipe along the Alabama Gulf Coast. The two containers can be installed side by side or on top of each other and don’t require a building–only a foundation pad and utility hook-ups. The project will be presented at the SPE ANTEC meeting in Charlotte, N.C., this month.