Heat-sealable vitrimeric polymer coatings for high-strength, reversible packaging bonds

Overview

ATSP Innovations is developing a vitrimeric polymer composition designed to meet the demanding requirements of heat-sealable flexible packaging. Vitrimers are a class of thermoset polymers containing dynamically exchangeable covalent bonds. When heated above their glass transition temperature, these materials can form adhesive bonds through bond exchange reactions, enabling rapid and reversible sealing. The proposed technology targets high bond strength, water resistance, and compatibility with industrial coil coating processes, while avoiding restricted chemistries such as vinyl chloride and styrene.

The core value proposition is a packaging coating that combines the mechanical performance and chemical resistance of thermosets with the processing speed and reworkability of thermoplastics. By enabling bonds that can be broken and reformed repeatedly without significant loss of performance, this technology offers packaging manufacturers a pathway to stronger, more reliable seals and improved material circularity.

Technical specifications

Key features and benefits:

• Reversible adhesive bonding through dynamic covalent bond exchange, allowing seals to be broken and reformed for more than 50 cycles without loss of function
• High mechanical strength demonstrated at greater than 60 MPa in pull-off testing and 15 to 20 MPa in thin bondline lap shear experiments
• Excellent water resistance with crack arresting performance in Boeing wedge crack tests (ASTM D3762) submerged in 70°C water for 60 days
• Low moisture uptake of less than 0.3 wt% after 24 hours in boiling water
• Cured pre-seal state that prevents blocking of coated films during storage and handling
• Compatibility with coil coating through solvent-borne application and deposition on aluminum foils
• Rapid heat sealing using induction, microwave, infrared, Joule, or embedded heating methods
• Free of restricted chemistries, including vinyl chloride and styrene

Technology readiness level

This technology is currently at a mid-to-late stage of development, with extensive prior validation in funded research programs. ATSP has already demonstrated that vitrimeric adhesive coatings can be deposited via solvent-borne methods, cured, and rapidly bonded using multiple heating schemes. Bond strength, reversibility, and water resistance have been characterized under relevant conditions, including prolonged submersion in hot water and boiling water exposure.

The proposed next phase of work focuses on tailoring the aromatic copolyester oligomer formulation for packaging-specific requirements, characterizing solution viscosity for coil coating, demonstrating bonding on representative heat seal equipment, validating bond strength after boiling water conditions per ASTM F904 and ASTM F2029, scaling to production-relevant process equipment, and establishing a food contact safety qualification plan with the packaging partner. The technology is positioned for collaborative refinement and pilot-scale validation prior to commercial deployment.