Industrial-scale production encompasses two primary systems: the twin-screw continuous method (accounting for 78% of production) and the conveyor-bed continuous method.
The twin-screw method utilizes an LSF-68 model reactive extruder, featuring a screw diameter of 68 mm and a length-to-diameter ratio of 48:1, wherein the material residence time is controlled within the range of 90 to 120 seconds.
The conveyor-bed method achieves continuous polymerization through a series of multi-stage reactors and is particularly suitable for processing high-viscosity materials. Both processes require precise control over the molar ratio of MDI to polyol (typically following the formulation PES:MDI:BDO = 1:3:2); operating within a reaction temperature range of 140–250°C, these methods yield granular products with a melt index ranging from 8 to 80 g/10 min.