rPET Sheet Extrusion: Recycling Technology for a Circular Plastics Economy

The global push toward a circular plastics economy has made rPET (recycled polyethylene terephthalate) PET (recycled polyethylene terephthalate) sheet extrusion one of the fastest-growing segments in the plastics industry. With regulations like the EU Single-Use Plastics Directive mandating 30% recycled content in PET bottles by 2030, and major brands committing to 100% recyclable packaging, the demand for food-grade rPET sheet is surging. This article explores the technology behind rPET sheet extrusion.

1. rPET Feedstock: From Bottle Flakes to Sheet

The rPET extrusion process begins with post-consumer PET bottle flakes. After collection, sorting, washing, and grinding, the resulting flakes must meet specific quality standards required for sheet production:

• Intrinsic Viscosity (IV): 0.70–0.85 dl/g (virgin PET is typically 0.80–0.85 dl/g)
• Moisture content after crystallization and drying: < 0.02%
• Contamination: < 100 ppm PVC, < 50 ppm other plastics
• Color: Clear, green, or blue sorted; no mixed colors
• Particle Size: 8–14 mm flakes, uniform size distribution

2. Crystallization and drying

Unlike virgin PET pellets, rPET flakes are amorphous and must be crystallized before drying to prevent them from sticking together. The crystallization process heats the flakes to 150–170°C, converting the amorphous structure to a crystalline form that can withstand the high temperatures of drying without agglomeration.

Jwell's rPET processing lines include integrated crystallization-drying systems that handle this step continuously:

• Crystallizer: Agitated vessel at 150–170°C, 20–40 minutes residence time
• Desiccant dryer: dew point below -40 °C, drying at 160–175 °C for 4–6 hours.
• Hopper loader: Vacuum conveying with moisture-proof design

3. IV Enhancement: Solid State Polycondensation (SSP)

During the recycling process, PET undergoes thermal degradation that reduces its intrinsic viscosity (IV), resulting in weaker mechanical properties. For food-grade and high-performance applications, the IV must be restored to 0.80+ dl/g through solid state polycondensation (SSP).

SSP reactors heat crystallized PET under vacuum or nitrogen flow at 210–230°C for 12–24 hours, building molecular weight through condensation reactions. This process also removes residual acetaldehyde — a critical requirement for food-contact applications where acetaldehyde limits are < 1 ppm.

4. rPET vs Virgin PET: Processing Differences

5. Jwell rPET Sheet Extrusion Lines

Jwell Machinery offers turnkey rPET sheet extrusion lines that integrate all processing steps from flake feeding to finished sheet winding. Our lines feature:

• Twin screw extruders with optimized mixing sections for homogenizing rPET with virgin PET
• Double-piston screen changers with 40–80 mesh primary and 120 mesh fine filtration
• Melt pumps for pressure stabilization, critical for consistent gauge with variable rPET feedstock
• Co-extrusion capability: ABA structures with rPET core and virgin PET skin layers
• Food-grade compliance: Lines designed to meet FDA, EU 10/2011, and GB9685 food-contact standards

Our rPET lines produce sheet with up to 100% recycled content, with mechanical properties and clarity that meet or exceed virgin PET specifications for most thermoforming applications.

Ready to enter the rPET market? Contact Jwell for a complete line proposal including crystallization, SSP, and extrusion systems.