Products: Line processes 3-layer GRF-PP pipes

Extrusion line manufacturer Cincinnati Extrusion GmbH (Vienna, Austria) has developed a system for extrusion of 3-layer pipes with a glass-fiber-reinforced middle layer. Such pipe can see use in, for example, heating and sanitary lines for hot- and cold-water transport in buildings. The pipe consists of two outer random polypropylene (PP) layers and a middle layer of homopolymer PP filled with a 10-20% (by weight) of short glass fibers.
 
The normal distribution of layer thicknesses in the 3-layer pipes varies between 25/50/25% and 33/33/33%. The glass-fiber reinforcement gives these pipes added stability and e-modulus.

For extruding these pipes, the machine manufacturer recommends an extruder combination consisting of two of its Talos single-screw extruders. While the extruder for the inner and outer layers is equipped with a 30 D processing unit and a grooved feed section, the extruder for the middle layer is just 25 L/D long and has a smooth processing unit with anti-wear protection to protect it from the fibers. The die, one of the company’s IRIS 25-3 coex triple-spiral mandrel dies, is suitable for pipe sized from 16-250 mm and can be adapted to different layer thickness distributions.
 
While pipes up to 32 mm are normally cooled in a full bath, spray cooling is recommended for larger pipe diameters. The company combined both in a variable water cooling bath which, depending on the application, can be switched from spray bath cooling to full bath cooling. —mpweditorial@cancom.com