The peel strength of acrylic double-sided tape is a core indicator of its adhesive performance, influenced by multiple factors including the tape's inherent properties, the properties of the adhered materials, process parameters, and environmental conditions. These factors interact to determine the tape's adhesive reliability in practical applications.
The physical properties of the tape substrate directly affect peel strength. The substrate material (e.g., polyester, polypropylene) and thickness are key factors. A harder substrate (high elastic modulus) consumes more energy during bending deformation in testing, resulting in significantly higher peel strength. For example, increasing the thickness of an aluminum foil substrate may increase peel strength due to increased deformation work. Simultaneously, surface treatments of the substrate (e.g., corona treatment) can enhance surface polarity, improve the wetting effect between the adhesive and the substrate, and thus optimize adhesive performance.
The chemical composition and structure of the adhesive play a decisive role in peel strength. The molecular weight distribution of acrylic adhesives has a significant impact. Widely distributed adhesives, containing more low molecular weight components, have enhanced fluidity, better wetting of the adhered material surface, and improved interfacial molecular interactions, thereby increasing peel strength. Furthermore, introducing polar monomers (such as acrylic acid) can increase the polarity of adhesive molecules, significantly enhancing adhesion to polar substrates, while also improving the cohesive strength and elastic modulus of the adhesive layer. The amount of crosslinking agent is also crucial; appropriate crosslinking can improve the cohesive strength of the adhesive, but excessive crosslinking will lead to increased bulk viscosity, thus reducing peel strength.
The material and surface condition of the substrate significantly affect peel strength. Different substrate materials (such as metal and plastic) exhibit significantly different adhesion to the tape due to differences in surface energy. Surface roughness is equally critical; a rough surface prolongs the time it takes for the adhesive to reach wetting thermodynamic equilibrium, with a particularly pronounced effect on tapes with poor initial tack. In addition, the degree of matching between the surface tension of the substrate and the surface tension of the tape is also essential; when they are close, the wetting effect is optimal, and the peel strength reaches its peak.
Test process parameters directly affect the peel strength value. The peel angle is an important variable; in 90° and 180° peel tests, the substrate deformation is different, leading to differences in test results. Generally, thin tapes (thickness < 0.3 mm) are more suitable for 180° peel tests, while thick tapes (thickness > 0.3 mm) are more suitable for 90° peel tests. Peel speed is also crucial; at low peel speeds, the adhesive behaves like a viscous fluid, easily leading to cohesive failure; at high peel speeds, the elastic component increases, potentially causing interfacial adhesion failure, resulting in a non-linear peel strength characteristic with speed.
Environmental factors have a long-term impact on the peel strength of acrylic double-sided tape. Increased temperature reduces the bulk viscosity of the adhesive, but may simultaneously weaken cohesive strength, leading to a decrease in peel strength. Increased humidity disrupts the interfacial bonding conditions of the adhesive, especially in humid environments, where water molecules may penetrate to the adhesive interface, reducing adhesion work. Ultraviolet radiation causes adhesive molecular chain breakage, leading to a decrease in cohesive strength, and a significant reduction in peel strength after long-term exposure.
Storage conditions have a significant impact on tape performance. High temperatures accelerate adhesive aging, leading to a decrease in bulk viscosity and cohesive strength. High humidity environments can cause adhesives to absorb moisture, damaging their chemical structure. Direct sunlight can trigger photo-oxidation, leading to molecular chain degradation. Therefore, adhesive tapes should be stored in a cool, dry, and well-ventilated environment to avoid irreversible damage to their performance caused by extreme conditions.
Lamination process parameters directly affect the initial bonding effect of the adhesive tape. Insufficient bonding pressure will result in inadequate contact between the adhesive and the substrate, forming microscopic voids and reducing interfacial adhesion work. Too short a bonding time may prevent the adhesive from fully wetting the surface of the substrate, affecting bond strength. Therefore, in practical applications, bonding pressure and time must be strictly controlled to ensure a sufficient and stable bond between the adhesive and the substrate.
