Recyclable naphthalate polyester barrier coatings for PET packaging

Overview

This solution offers recyclable naphthalate polyester (PEN and PEN-based copolyesters) as barrier coatings for PET packaging articles. Conventional high-barrier packaging relies on multi-material or multi-layer constructions that are difficult or impossible to recycle. In contrast, naphthalate polyesters supplied by Indorama Ventures are fully compatible with PET packaging designs and can be recycled within the standard PET recycling stream.

The technology delivers significantly improved barrier performance compared to PET, along with superior chemical and hydrolytic resistance, better mechanical properties, and enhanced protection against odors. Because naphthalates share similar refractive indices with PET, finished packaging articles retain high clarity and low haze. All materials are FDA-compliant and compatible with common PET processing methods.

Technical specifications

Barrier performance advantages over PET:

• Moisture transmission is 2-4 times lower in PEN films at 38°C/90% RH
• Oxygen transmission is 3-5 times lower in PEN films at 38°C/68% RH
• Carbon dioxide transmission is 4-6 times lower in PEN films at 38°C/0% RH
• PET-PEN copolyesters (PENCo) offer tunable barrier properties between PET and PEN levels
• Certain naphthalates can form a liquid crystal (LC) phase (Naph-LCP) with superior barrier characteristics

Application approaches:

• PEN or PENCo coatings applied to one or both sides of PET containers using spray, dip, slot-die, co-extrusion, or brush coating methods
• Full packaging articles produced entirely from recyclable PENCo material using standard PET molding processes
• Naph-LCP coatings applied to PET articles and processed to induce the LC phase

Additional benefits:

• High optical clarity and low haze due to refractive index matching with PET
• FDA-compliant for food contact applications
• Fully recyclable within existing PET recycling infrastructure
• Improved wear and abrasion resistance for select formulations

Technology readiness level

The technology is positioned for validation and pilot-scale demonstration. The research team has established the underlying barrier performance data for PEN, PENCo, and Naph-LCP formulations and outlined four distinct application pathways. Next steps involve coating trials on PET substrates using standard industrial coating methods and processing trials for full-article PENCo molding. The approach leverages commercially available naphthalate resins from Indorama Ventures, supporting a clear pathway from laboratory validation to commercial deployment in food, beverage, and consumer goods packaging.