Compounding with 50% Glass Microspheres

Coperion Werner & Pfleiderer in Germany (U.S. office in Ramsey, N.J.) has applied for a patent on a process for compounding and direct extrusion of plastic filled with hollow microspheres.

Coperion Werner & Pfleiderer in Germany (U.S. office in Ramsey, N.J.) has applied for a patent on a process for compounding and direct extrusion of plastic filled with hollow microspheres. The compound is a heat-insulating syntactic foam containing 50% by volume (30% by weight) Scotchlite glass microspheres from 3M Co. It forms one of eight layers in steel/PP composite pipe for undersea oil transport. The trick is not to crush the spheres during mixing. Coperion says its ZSK MegaVolume kneader, which has extra-high free volume in the screw, can blend the spheres into melted PP with minimal breakage. Microspheres are added halfway down the barrel with a twin-screw side feeder. The high-volume screw folds more air into the melt, so the machine has a special degassing vent to keep melt from escaping. The 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 processing line fits inside two air-conditioned, 40-ft shipping containers for mobile production of pipe on the Alabama Gulf Coast. The two containers can be installed side by side or on top of each other and need only a foundation pad and utility hook-ups. The project will be presented at the SPE ANTEC meeting in Charlotte, N.C., this month.