Tailored synthesis of heat-sealable and water-resistant polyester coatings

Overview

This solution addresses growing demand for sustainable alternatives to conventional polyethylene and polypropylene films used in fiber-based packaging. Conventional plastic films contribute to microplastic waste, creating a market need for compostable barrier coatings that deliver comparable performance. The technology is a modified polyester coating based on polybutylene succinate (PBS) copolymer blends, combining biologically derived and petroleum-derived monomers. This flexible feedstock approach accommodates both 100% bio-based and lower-cost petroleum-derived formulations depending on customer requirements. The coatings are designed to meet ASTM 6400 and BPI certification standards for compostability while providing strong heat-seal strength and water resistance for paper-based packaging applications.

Technical specifications

Key features:

• Polybutylene succinate-based copolymer blend using both bio-derived and petroleum-derived monomers
• Solvent-based coating system demonstrating strong heat sealing performance
• At 20 gsm coat weight on 70 gsm virgin kraft paper, tensile strength measurements reached 8.9 newtons per inch with fiber tearing and over 99 newtons per inch in shear
• Water resistance demonstrated with no penetration observed after 30 minutes on a 1 square inch coated surface
• Designed to be fully biodegradable and compostable, targeting BPI certification
• Potential for cost reduction through covalent blending with starches while maintaining barrier and seal properties

Testing and validation underway:

• COBB testing for water absorption
• Hot oil soaking for oil resistance
• Kit testing for grease resistance
• ASTM E96 water vapor transfer rate evaluation
• Heat seal strength optimization

Technology readiness level

The solution is currently in the lab phase. Proof-of-concept synthesis has been completed at up to 200 gram scale, and formulation testing on paper substrates has yielded positive results. Material optimization and performance evaluation are ongoing, with a water-based emulsion version in development to replace the current solvent-based system. Sampling is expected by mid to late Q1 2024, with pilot projects anticipated by end of Q2 or early Q3 2024. ASTM 6400 biodegradation certification testing will run concurrently. Contract manufacturers have been engaged and scaling is not expected to be a barrier, with the first large-scale batch planned for Q3 2024 to support pilot projects and initial orders.