Biodegradable pore-sealing coating technology for high-performance moisture barrier films

Overview

This solution addresses a critical limitation in metallized films used for food and consumer packaging: microscopic pinholes and imperfections in the thin metallic layer that allow moisture vapor to pass through. By sealing these pores using commercially available roll-coating and calendering processes, the technology aims to achieve a water vapor transmission rate (WVTR) of less than 0.3 grams per square meter per day — a benchmark for high-barrier packaging.

Three complementary sealing strategies are being pursued: coupling agents that bond to the metal surface, acid-base reactions that fill pores, and phase change materials that physically close imperfections. All approaches rely on food-contact safe, biodegradable materials aligned with compostability standards. The result is a moisture barrier film suitable for compostable and environmentally responsible packaging without sacrificing barrier performance.

Technical specifications

Core technology:

• Roll-coatable and calenderable coatings designed to seal pores and pinholes in metallized films
• Three sealing mechanisms under investigation: coupling agents, acid-base pore-filling reactions, and phase change materials
• Materials selected for food-contact safety and biodegradability

Application methods:

• Calendering or roll-coating of phase change materials directly onto the metal film
• Two-sided calendering or roll-coating with subsequent chemical treatment to drive acid-base interactions within metal pores
• Application of coupling agents via co-extrusion, spray, or calendaring processes

Performance target:

• Water vapor transmission rate below 0.3 g/m²/day

Validation standards:

• Water vapor permeation measured using the "Cups Method" following ISO 7783
• Compostability and soil testing per ASTM D5338-15 or ASTM D6400

Technology readiness level

The underlying science draws on Trucapsol's established expertise in manufacturing microcapsules with defect-free membranes for liquid core encapsulation. Scanning electron microscopy has visually confirmed the pore-sealing effect in microcapsule membranes, providing confidence that the same sealing principles can be transferred to metallized films. The next phase of validation focuses on modifying metal films using the three roll-coating approaches and measuring barrier performance against the WVTR target, alongside compostability testing under recognized ASTM standards.