Coating & Laminating
Silicone release coating curing: a key driver of converting eff iciency
and performance By Sébastien MARROT, product manager, silicone release coatings and pressure sensitive adhesives, Bluestar Silicones (formerly Elkem Silicones)
However, this fl exibility comes with increased process sensitivity. Any deviation in curing conditions can lead to undercured coatings. The consequences are critical: poor anchorage, silicone transfer, unstable release forces and unpredictable aging behaviour. These defects are often not immediately visible but can create major issues during converting, including irregular cut edges, unstable matrix stripping and web breaks. Ultimately, they can compromise dispensing performance and reliability at end use.
UV CURING WINDOW: FAST AND STREAMLINED
S
ilicone release coatings remain the reference technology for manufacturing high-performance release liners used in pressure-sensitive adhesive applications. Beyond formulation design and achieving uniform substrate coverage, the curing step is decisive as it governs coating integrity, anchorage and ultimately release performance once laminated. Two main curing technologies coexist today, thermal and UV and understanding their respective process windows is essential to ensure consistent, fi t- for-purpose release liners.
THERMAL CURING WINDOW: VERSATILE AND TUNABLE
Thermally cured silicones include solvent-based, emulsion and solventless systems. These rely on curingchemistries that require suffi cient thermal energy to achieve full crosslinking. Consequently, the coating line confi guration plays a critical role. Industrial drying systems must provide adequate dwell time, typically through multi-zone ovens that may extend over several tens of meters depending on line speed and formulation reactivity. The choice of drying technology is also critical to ensure uniform heat transfer, controlled airfl ow and stable web handling. Air fl otation ovens provide homogeneous, contact-free drying and avoid coating disturbance, while contact systems can improve effi ciency but increase the risk of marking.
Temperature control is not limited to peak temperature but extends to the full profi le along the
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oven, balancing drying and curing. For solvent-based and emulsion systems, the carrier must fi rst evaporate before crosslinking can fully develop. Heating must therefore be introduced progressively to ensure proper carrier removal prior to fi lm consolidation, avoiding entrapment and ensuring uniform fi lm formation. In multi-zone ovens, this is typically achieved through a profi le that increases toward the middle of the oven and decreases toward the exit to reduce residual stresses and stabilise the web. This fi nal stage prepares the web for rewinding, where cooling is required to avoid deformation, blocking and tension instability. In contrast, solventless systems do not require evaporation, allowing a direct focus on achieving curing conditions with fewer constraints at the beginning of the process. In any case, moisture management remains essential for paper substrates as uneven drying can induce curling or dimensional instability.
Substrate sensitivity further defi nes the thermal curing window. PE, PP and PCK are the most temperature-sensitive substrates, followed by PET, CCK and fi nally glassine and kraft papers. The curing profi le must be adjusted to avoid substrate shrinkage while ensuring suffi cient silicone crosslinking. Within these constraints, thermally cured silicones off er high formulation fl exibility across broad processing temperatures. By adjusting polymer structure, crosslink density, additives and catalyst systems, coaters can achieve a wide spectrum of curing kinetics and release levels. This versatility is essential when addressing all types of adhesive technologies.
UV-curable silicone technologies off er a fundamentally diff erent approach. These systems rely on photoinitiated reactions that occur instantaneously upon UV exposure. As a result, thermal ovens are no longer required, enabling compact coating lines and reduced energy consumption. The transition from conventional mercury vapor lamps to UV LED technology further reinforces these benefi ts. UV LED systems consume substantially less energy, operate without hazardous mercury, generate no ozone and off er instant on/off capability, improving both safety and operational effi ciency.
In addition, UV curing is well suited for temperature-sensitive substrates and eliminates constraints related to drying. UV silicones can be supplied as ready-to-use systems, unlike thermally cured formulations, which require multi-component handling and precise mixing. However, limitations remain. The achievable release range is often narrower than with thermal technologies and release stability can be more sensitive depending on the adhesive system, requiring careful validation under real application conditions.
CONCLUSION
Selecting between thermal and UV silicone curing must be application-driven, balancing substrate constraints, productivity and performance requirements. Thermal systems off er a versatile and tunable curing window, while UV technologies provide a fast and streamlined route to high- performance release liners. In both cases, mastering the silicone curing process remains essential to ensure converting effi ciency and end-use performance.
July/August 2026 19
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