ptimization of Release Film's Residual Adhesion Performance and Control Strategies for Release Force under High-Temperature Aging (Part 1)
The Trade-off between Residual Adhesion and High-Temperature Rise of Release Force: Pursuing an extremely high residual adhesion rate usually requires the coating to have extremely low surface energy and good flexibility (which may require a slightly lower cross-linking density), but this may sacrifice some high-temperature stability.
Conversely, pursuing excellent high-temperature stability requires a dense cross-linked network (high cross-linking density), which may make the coating a little "harder". For some sensitive tapes, this may increase the peeling resistance or slightly affect the residual adhesive (although phenyl silicone oil itself usually helps reduce residual adhesive).
Finding the optimal balance is the core art of formula design.
Strategies to Improve Residual Adhesion
High residual adhesion means that the release film can peel off the tape cleanly without leaving residual adhesive. The main optimization direction is to reduce the affinity/adhesion between the surface of the release film and the adhesive.
Precise Control of Coating Process
Control of Coating Amount: An excessively thin coating will lead to poor coating continuity, many defects, unstable release force, and increased risk of residual adhesive; an excessively thick coating will result in high costs and may affect subsequent processing (such as die-cutting) and high-temperature stability. It is crucial to find the optimal coating amount for specific tapes and applications.
Ensure Coating Uniformity: Use high-precision coating equipment, strictly control parameters such as coating roller pressure, speed, and tension to ensure a high degree of uniformity in coating thickness both horizontally and vertically.
Optimize Curing Conditions: Ensure complete curing of the silicone oil coating. Insufficient curing temperature and time will lead to incomplete cross-linking, insufficient cohesion of the coating, and easy silicone oil transfer; excessive curing may make the coating brittle. Precisely control the oven temperature curve and ventilation.
Optimize Coating Formula
Select Low Surface Energy Silicone Oil: Priority is given to modified silicone oils with large sterically hindered groups in their molecular structure.
Adjust Cross-Linking Density: Excessively high cross-linking density may make the coating too hard, increasing the number of microscopic contact points with the adhesive, which may instead increase peeling resistance and the risk of residual adhesive. However, it should be noted that excessively low cross-linking density will affect the stability of the coating.
Use Efficient Release Control Agents: Add special additives to the formula (such as MQ silicone resin with a specific molecular weight, fluorosilane, specially modified polysiloxane, etc.). These additives can effectively migrate to the coating surface, further reduce surface energy, improve release smoothness, and thus significantly reduce residual adhesive.
Optimize Additive Compatibility: Ensure that all components in the formula (silicone oil, cross-linking agent, catalyst, additives) have good compatibility to avoid phase separation leading to uneven coating surface and affecting the release effect.
Select Appropriate and Treated Base Films
Surface Tension/Wettability of Base Film: The surface tension of the base film must be sufficiently high (usually requiring corona treatment) to ensure that the silicone oil coating can well wet, spread, and firmly adhere to the base film.
Surface Flatness/Roughness of Base Film: A base film with an excessively rough surface requires more silicone oil to fill the pits to form a continuous coating, and may affect the stability of release force. Choosing a base film with high surface smoothness helps to obtain a more uniform and thinner coating and improve the release performance.
