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Constantia Flexibles, in collaboration with thermal technology specialist watttron, has developed a new approach to lid sealing that enables both polypropylene (PP) and aluminum lids to be sealed on PP cups using a single system. The initiative builds on Constantia Flexibles’ PPCover, a mono-material PP lidding solution designed to meet recyclability standards without compromising performance. While PPCover delivers clear environmental benefits, integrating it into existing sealing machines presented a technical challenge: ensuring consistent, high-quality seals across different lid materials without introducing inefficiencies or material deformation.
Traditional sealing systems typically heat the entire sealing head, which can lead to issues such as curling due to excess heat exposure. Although not widespread, this risk prompted Constantia Flexibles to explore more precise and adaptable sealing methods to ensure long-term reliability and compatibility.
The solution emerged through a partnership with watttron, whose ring-heating technology applies heat only to the outer sealing ring. This targeted method reduces thermal stress on the lid material and significantly improves energy efficiency. The system heats and cools rapidly—typically at a rate of 10 to 20 °C per second—and maintains the set temperature with a high degree of accuracy (±1 °C). These features not only support consistent sealing performance but also allow the system to be safely powered down during production stops, contributing to energy savings of up to 50% compared to conventional sealing methods.
Lab-scale tests using PPCover confirmed the effectiveness of the approach, demonstrating excellent peel behavior, strong internal pressure resistance, and reliable sealing for both PP and aluminum lids using the same equipment. Marcus Stein, CEO of watttron, noted, “We developed our ring-heating technology to deliver precise energy exactly where it’s needed—no more, no less. That precision not only improves quality and flexibility, but also contributes meaningfully to energy efficiency in packaging lines.”
The universal sealing technology offers manufacturers a number of practical advantages. It eliminates the need for separate machines or setups for different lid materials, simplifies production processes, and reduces equipment complexity. The system also integrates with 100% inspection capabilities, enabling real-time detection and removal of defective cups to ensure consistent product quality. Claus Dworschak, Market Product Manager Die Cut Lids at Constantia Flexibles, commented, “This is a strong one-fits-all solution in dairy lidding. It simplifies operations and enhances quality—exactly what our customers need.” By combining material innovation with precision engineering, Constantia Flexibles and watttron are helping to shape a more adaptable and efficient future for packaging.
