Recyclable PCL nanocomposite coatings for paperboard packaging

Overview

The University of Zagreb has developed biodegradable polycaprolactone (PCL) nanocomposite coatings designed for paperboard packaging. These coatings are engineered to improve the mechanical and barrier properties of paper-based materials while ensuring that the packaging remains compatible with standard recycling processes. By incorporating nanoparticles such as silicon dioxide (SiO2), aluminum oxide (Al2O3), and zinc oxide (ZnO) into the PCL matrix, the research aims to create sustainable packaging solutions that do not compromise the quality or recyclability of the resulting pulp.

Technical specifications

The coatings are prepared by dissolving PCL biopolymer in an ethyl acetate solvent, followed by the dispersion of nanoparticles. Key features and findings include:

• Enhanced barrier properties: The nanocomposite coatings improve water vapor barrier performance and UV stability, which helps maintain the color stability of printed packaging.
• Recyclability: Laboratory-scale studies demonstrate that these coatings do not adversely impact the optical properties of recycled fibers, allowing for effective ink removal during standard flotation deinking processes.
• Material composition: The coatings utilize PCL modified with specific nanoparticles (SiO2, Al2O3, and ZnO) to optimize surface characteristics and hydrophobicity.
• Application: The coatings are applied to offset-printed paperboard, with research focusing on achieving optimal ink particle sizes during disintegration to facilitate efficient separation.

Technology readiness level

The technology is at TRL 3, representing a proof-of-concept stage. The University of Zagreb has conducted laboratory-scale research to evaluate the optical and mechanical properties of recycled pulp coated with these materials. While the results confirm that the coatings do not hinder recycling, further research is required to address the migration of nanoparticles into wastewater and the long-term...