Patent ID: 7156550

Claim:
An apparatus for plasticating polypropylene resin comprising: a barrel having an inlet through which resin enters the barrel, an outlet through which plasticated resin leaves the barrel, and an inner surface; a rotatable screw located within and cooperating with the inner surface of the barrel, having a longitudinal axis extending from the inlet toward the outlet, and including sections extending axially and arranged in a sequential series along the axis, the screw further including: a core extending along the axis; a main flight located on and projecting radially from the core, extending in a helix along the axis; a feed section; a transition section following the feed section; a first metering section following the transition section; a barrier melting section following the metering section; and a reorientation and second metering section following the barrier melting section, said reorientation and second metering section having a secondary flight and the main flight passing through the reorientation and second metering section having a pitch less than a pitch of the main flight in the barrier melting section.