Reprocessing Crosslinked Polyurethane with Green Catalysis Methods

NU 2022-155

INVENTORS

• William Dichtel (Northwestern University, Weinberg College of Arts & Science, Department of Chemistry)*
• Molly Sun

SHORT DESCRIPTION

This method reprocesses crosslinked polyester polyurethane using green zirconium-based catalysts. It lowers environmental and health risks while supporting various molding processes.

BACKGROUND

Conventional reprocessing methods for thermoset polyester polyurethane rely on toxic catalysts and energy-intensive processes. These approaches often use harmful organotin compounds and inefficient techniques, leaving a clear need for safer, sustainable alternatives.

ABSTRACT

The invention employs green zirconium-based catalysts to reprocess crosslinked polyester polyurethane. It effectively converts both model and commercial materials using processes such as compression molding, twin-screw extrusion, and injection molding. The method supports up to four processing cycles without residual toxicity. Cryogenic milling enables precise catalyst integration and eliminates the need for solvents. These outcomes demonstrate a viable, environmentally friendly solution for PU recycling.

MARKET OPPORTUNITY

The global market for the chemical recycling of plastics was valued at nearly $3.0 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 12.3% through 2030. This growth is driven by intense regulatory pressure to create a circular economy and strong corporate sustainability commitments within the $91.5 billion global polyurethane industry. The primary market for this technology includes major polyurethane producers, automotive and construction material manufacturers, and industrial-scale waste management companies. (Source: Grand View Research: "Chemical - Plastic recycling services market outlook").

DEVELOPMENT STAGE

TRL-4 - Prototype Validated in Lab: A laboratory-scale prototype successfully demonstrated the method’s ability to process both commercial polyester and polyether polyurethanes using green zirconium-based catalysts.

APPLICATIONS

• Bulk reprocessing of thermoset PU using non-toxic chemicals
• Compression molding of reprocessed PU materials
• Twin-screw extrusion for PU recycling
• Processing mixed plastic waste streams including PU

ADVANTAGES

• Eliminates toxic catalysts: Replaces harmful organotin with green zirconium-based catalysts
• Multiple reprocessing cycles: Enables up to four consistent cycles
• Diverse material compatibility: Effectively processes both polyester and polyether polyurethanes
• Solvent-free processing: Cryogenic milling integrates catalysts without using solvents

PUBLICATIONS

Green Catalysts for Reprocessing Thermoset Polyurethanes. Macromolecules 2023, 56, 17, 6978–6987

IP STATUS

US, CN, EP, IN, JP, KR, and MX Patents Pending (Nationalized PCT WO2024044610A2)