What Are The Components Of The Adhesive Strength Of A Protective Film?

The adhesion, tack, and cohesive force of a protective film distinguish the adhesive force between the protective film substrate and the adhesive, the peel strength after use, and the adhesive force of the adhesive itself. Understanding the meaning of these forces allows for a better understanding of the performance of the protective film, enabling the full utilization of different protective film products.

Adhesion: This refers to the bonding force between the adhesive and the film. If the tack force is greater than the adhesion force, the bonds between the adhesive molecules and the film will break when the protective film is peeled off, resulting in delamination.

Tack: This refers to the force required to peel the protective film from the surface after a certain period of time. Tack is related to the material being applied, pressure, application time, peeling angle, and temperature. Generally, tack increases with time and pressure. The tack of the protective film should not increase excessively to ensure no residue remains after peeling. A 180-degree peel test is generally used to measure tack.

Cohesion: refers to the internal strength of the colloid. The cohesion of the colloid used as a protective film must be very high; otherwise, when the protective film is torn off, the internal cracks of the colloid will cause residue. The method for measuring cohesion is to attach the protective film to a stainless steel surface, suspend a certain weight on the protective film, and measure how long it takes for the protective film to be pulled off by the weight. If the adhesion is greater than the cohesion, the bonds between the colloid molecules will break when the protective film is torn off, resulting in residue.