Process for compounding thermoplastic resin and fibers

A process for compounding reinforcing fibers with a thermoplastic resin in an apparatus comprising a resin extruder having a rotatable extruding screw extending therein and a compounding extruder having a single, continuous straight barrel defining an inlet end and a discharge end of said compounding extruder and an elongated power screw extending within said barrel between said inlet end and said discharge end thereof, said process comprising:

• rotatably driving said extruding screw and said power screw at predetermined speeds;
• introducing discrete lengths of reinforcing fibers into said compounding extruder at a first inlet port on said inlet end of said barrel and mechanically working and heating said fibers while continuously confined within said inlet end of said barrel by said power screw;
• directing thermoplastic resin material into said resin extruder and heating and melting said resin material by the rotating action of said extruding screw to form a fluid, molten mass of thermoplastic resin;
• and
• feeding said molten thermoplastic resin in a pressurized state from said resin extruder into said compounding extruder at a second inlet port on said inlet end of said barrel downstream from said first inlet port between said first inlet port and said discharge end of said barrel and moving the mechanically worked and heated fibers by said power screw past said second inlet port, and thereby forming a homogeneous mixture of thermoplastic resin and discrete lengths of reinforcing fibers in said compounds extruder by the rotating action of said power screw;
• and
• discharging said homogeneous mixture from said discharge end of said compounding extruder.