On the Applicability of Polyurethane Adhesives in the Flexible Packaging Industry

Polyurethane adhesives have excellent applicability in food soft packaging and are widely used in composite films, aluminum-plastic bags, steaming bags, etc. Their main advantages lie in excellent bonding strength, flexibility, heat resistance, and chemical resistance, which can effectively adapt to various harsh conditions in the processing, transportation, and storage of food packaging. Especially for two-component reactive polyurethane adhesives, through the reaction of isocyanate and polyol to form a cross-linked structure, after curing, a stable high-molecular network is formed. Not only is the bonding strength strong, but it can also maintain stable performance even under high-temperature steaming (such as 121°C or 135°C), meeting the requirements of sterilization processes.

     In addition, polyurethane adhesives have good adhesion to various substrates (such as PET, PA, CPP, aluminum foil, etc.), suitable for multi-layer composite structures, and enhance the barrier properties and preservation effects of packaging. With increasingly strict food safety regulations, solvent-free and water-based polyurethane adhesives have gradually become the mainstream, as they do not contain or contain only a very small amount of volatile organic compounds (VOC), significantly reducing the risk of residual solvents contaminating food. At the same time, modern polyurethane products, through optimized formulations, effectively control the content of free isocyanate monomers to ensure compliance with food contact material standards such as GB 9685.

     However, during use, attention still needs to be paid to raw material purity, curing conditions, and migration risks to ensure that the final product meets food safety requirements. Overall, with the continuous advancement of technology and the promotion of environmental regulations, polyurethane adhesives, with their comprehensive performance advantages, remain an indispensable key material in the field of food soft packaging.