Polyurethane Adhesive (PU adhesive) is one of the most crucial materials in modern flexible packaging composite processes, and its application characteristics are extremely prominent, mainly reflected in the following aspects:
1. Excellent comprehensive bonding performance: This is its most core advantage. Polyurethane adhesives have excellent bonding strength and adaptability to a variety of common substrates in flexible packaging, such as BOPP, PET, PA, AL aluminum foil, CPP, PE, etc. Whether it is the lamination between plastic films or the lamination of plastic with polar materials such as aluminum foil, it can form a firm bonding layer, ensuring the structural integrity of the packaging bag and avoiding delamination.
2. Excellent durability: Flexible packaging needs to withstand the tests of the contents (such as oily foods, spicy foods, chemicals, etc.) as well as subsequent processing conditions such as sterilization and cooking. Polyurethane adhesives have excellent oil resistance, chemical resistance, cold resistance and high-temperature resistance. Especially for two-component reactive polyurethane adhesives, their cross-linked network structure can provide excellent heat resistance (such as 100℃ to 135℃), meeting the requirements of high-temperature sterilization packaging.
3. Good process adaptability: Polyurethane adhesives come in a wide variety of types, including solvent-based, solvent-free, and water-based ones, which can meet different processing equipment and process requirements. It has good leveling property, uniform coating, is easy to operate, and can achieve high-speed composite production, meeting the pursuit of high efficiency in the flexible packaging industry.
4. Excellent hygiene and safety performance: Through carefully designed and strictly controlled synthetic processes, modern polyurethane adhesives (especially those that comply with relevant regulations such as the FDA) have stable chemical structures, low odors, and low migration, effectively preventing contamination of the packaged contents (especially food) and ensuring food safety.
5. Excellent transparency and flexibility: The cured adhesive layer is colorless and transparent, which does not affect the appearance of the packaging or the printing effect. Meanwhile, its adhesive film is soft and flexible, matching the flexibility of the soft packaging base material. It is less likely to crack during the rubbing, squeezing and dropping of the packaging bag, thus protecting the goods.
In conclusion, polyurethane adhesives, due to their irreplaceable comprehensive performance, have become indispensable key materials for the production of high-performance and high-quality flexible packaging products, such as high-temperature retort bags, vacuum packaging, aluminum-plastic composite bags, heavy-duty packaging, etc., and are widely used in many fields such as food, medicine, and daily chemicals.
