TPU Reactive Extrusion Plant in China

Illustration notice. Process illustrations are not verified photographs of this installation.

Project reference basis. Figures and configuration details are reported in the supplied project brief. They are reference values for the stated application, rather than verified acceptance results or a guarantee for another installation. Confirm the source records, material, tooling, operating schedule and test method when assessing a comparable project.

A leading high-performance elastomer resin producer in Ningbo partnered with Haifeng to establish a greenfield one-shot thermoplastic polyurethane (TPU) reactive extrusion and underwater pelletizing facility. The project was designed to manufacture high-purity, uniform TPU pellets for athletic footwear foaming and robotic cable applications.

Prior to this installation, the client utilized multi-stage batch reaction kettles coupled with strand pelletizers. This setup suffered from batch-to-batch inconsistencies, with melt flow index (MFI) variations exceeding ±18% and frequent filament breakages during strand cooling. The resulting broad molecular weight distribution caused poor foaming yields during downstream supercritical CO₂ expansion.

Haifeng delivered an automated continuous plant centered on the HF-TPU75-REX reactive extrusion platform. Featuring four-stream closed-loop mass flow dosing, an extended L/D = 56 screw architecture, and direct underwater pelletizing, the line achieved an operating output of 1.2 tons/hour, producing uniform spherical pellets with an ultra-narrow molecular weight distribution (Mw/Mn ≤ 1.85).

Haifeng engineered and commissioned a turnkey continuous reactive compounding plant spanning 24 meters in process length. The raw material system incorporates four independent feed streams where polyester polyol, liquid pure MDI, 1,4-butanediol (BDO), and specialty catalysts are metered continuously into the extruder feed zone under a positive nitrogen atmosphere.

The chemical components enter a co-rotating twin-screw extruder with an extended process length of L/D = 56. Across 14 independently regulated barrel zones, the reactants undergo controlled stoichiometric mixing, high-temperature chain extension, and dual-port vacuum de-volatilization, stripping volatile oligomers under 0.05 kPa negative pressure.

A heated melt gear pump draws the reacting polymer from the screw tips, stabilizing delivery pressure into a multi-port heated die plate. As strands emerge into the water cutting chamber, a hydraulic multi-knife cutter cuts them into spherical beads in conditioned 45°C water. The pellet slurry is transferred directly to a high-speed centrifugal dryer and a vibratory classifier, discharging dry, dust-free TPU pellets into packing silos.