The Science of Peel Strength: What It Means for Your Product

In the adhesive industry, 'peel strength' is a term used to quantify the adhesive force between two bonded substrates. It is a critical quality control metric that directly predicts how a package or laminated product will perform under real-world stresses. Whether it's a flexible pouch that needs to withstand the rigors of shipping and handling or a medical device package that requires a sterile barrier, a bond with high and consistent peel strength is essential for ensuring product integrity, safety, and consumer satisfaction. Understanding this metric, how it is measured, and what it signifies is key to producing reliable and high-quality goods that meet both regulatory and market expectations.

Peel strength is typically measured using a machine called a tensiometer or a universal testing machine. In a standard test (like a T-peel or a 180° peel test, as defined by ASTM standards), a strip of the laminated material is prepared, and the two layers are separated at one end to create 'legs'. These legs are then clamped into the jaws of the tensiometer, which pulls them apart at a constant speed. The machine precisely measures and records the average force required to continue separating, or 'peeling,' the two layers. This force is usually reported in units like Newtons per meter (N/m) or grams-force per inch (gf/in). The resulting value provides a quantitative, repeatable, and comparable measure of the bond's performance.

The required peel strength varies greatly depending on the application. For a permanent laminate in a structural application, the goal is often 'fiber tear' or 'film tear,' where the substrate itself fails before the adhesive bond gives way. This indicates that the adhesive bond is stronger than the material it is holding together—the highest possible level of adhesion. In other cases, such as a peelable lidding film for a yogurt cup, a specific, controlled peel strength is desired. The lid must adhere strongly enough to protect the product and provide a hermetic seal, but peel away cleanly and easily for the consumer without tearing or leaving residue. This requires a sophisticated adhesive formulation that balances adhesion and cohesion.

At Kubron, our research and development and quality control laboratories perform rigorous peel strength testing on all our formulations. We don't just test under standard ambient conditions; we analyze performance after exposure to various environmental factors, including heat, humidity, and chemical agents, to simulate the entire product lifecycle. We test bonds after aging, after submersion, and after freezer storage. This ensures our adhesives, like Aquatack Plus PF, provide not only superior initial peel strength but also maintain that strength over time, regardless of the conditions the final product will face. This meticulous commitment to testing and quality guarantees a bond you can trust, protecting your product and your brand's reputation in the marketplace.