A Steam-Free Solution for Curl Control

Presented by Joonas Kaariainen, Valmet

Coating and laminating machines are facing challenges in terms of energy, production, quality and costs, curling being one of the most crucial quality challenges for the producers. Lay-flatness can be controlled through moisturizing, because cross-directional curling is influenced by uniform and comprehensive wetting of all fibers. Traditional methods of remoisturizing, such as steam boxes and conventional moisturizers, face challenges like capacity limitations, energy inefficiencies, and a lack of control over moisture profile uniformity, impacting lay flatness control. Moreover, the conventional practice of steam humidification contributes to carbon dioxide (CO2) emissions, primarily stemming from the energy source utilized in the steam production process. This paper explores an efficient closed-loop moisture control and moisturizing approach that eliminates the need for steam, ensuring stable laminate flatness. The system includes air atomized water spray system, online quality measurements, and automatic controls for curl and moisture. Steam-free laminate production can be achieved through a moisturizer with its air-atomized micro-droplet nozzles with a 50-mm spacing that are controlled with high-accuracy linear actuators. Remoistening capacity of this technology is up to five times higher compared with conventional systems, which makes it the most efficient system for curl and moisture control in the market. A state-of-the-art quality measurement system measures precisely the correct coat weight and moisture, online. The measurement technology enables high-resolution cross direction profiles of all silicone and adhesive types. CD/MD Multivariable Controls together with high resolution moisturizing technology keeps the liner in needed moisture level, providing flat laminate in all process conditions, like grade changes and machine ramp-up. With the closed-loop control system, the final laminate remains flat through speed, grade, or other process changes, reducing waste in production, which leads to reduced production costs and raw material usage.