A comparison between polyurethane adhesives and traditional flexible packaging adhesives
In the flexible packaging industry, adhesives are the key to determining the performance of composite materials. Compared with traditional adhesives (such as one-component pressure-sensitive adhesives, solvent-based rubber adhesives, etc.), polyurethane adhesives have become the undisputed first choice for modern flexible packaging due to their outstanding comprehensive performance. Their advantages are mainly reflected in the following aspects:
1. Excellent bonding performance and wide applicability
Traditional adhesives often have poor bonding effects on specific materials such as polyethylene and polypropylene, and have limitations. Polyurethane adhesives exhibit extremely strong adhesion to a variety of flexible packaging substrates, including various plastic films, aluminum foil, aluminum-coated films, nylon, etc. It can effectively overcome the surface inertness of non-polar materials such as polyethylene and polypropylene, forming a firm bonding layer. Especially when dealing with aluminum-coated films that are prone to curling and have high bonding difficulty, it can effectively prevent the "transfer" phenomenon and ensure the integrity of the packaging appearance and barrier performance.
2. Excellent resistance to media and compatibility with contents
Flexible packaging often needs to hold oily, acidic, spicy and other foods or chemicals. Traditional adhesives are prone to degradation and delamination in this environment. After curing, polyurethane adhesives form a cross-linked network structure, which has excellent resistance to oil, acid, ester solvents and high-temperature cooking. This ensures that during storage and transportation, the packaging can maintain the stability and safety of the adhesive structure even when facing harsh contents, and will not contaminate the contents due to component migration.
3. Excellent mechanical properties and durability
Flexible packaging needs to withstand friction, compression and deformation during production (such as bag making and filling) and use. The adhesive film formed after the curing of
Polyurethane Adhesive is both flexible and strong, featuring high peel strength and excellent impact resistance and fatigue resistance. This makes the composite packaging bags more durable, less likely to break or delaminate at the folded edges or sealing points, significantly enhancing the reliability and shelf life of the packaging.
4. Wide adaptability to processes
Polyurethane adhesives (especially two-component reactive types) can flexibly adjust their operation time, curing temperature and final performance through formula design, easily meeting the process requirements of different grades ranging from ordinary light packaging to high-temperature steam-cooked packaging.
Summary
In conclusion, compared with traditional adhesives, polyurethane adhesives demonstrate overwhelming advantages in terms of bonding strength, applicable material range, resistance to erosion by contents, and the physical durability of the final packaging. It perfectly meets the demands of the flexible packaging industry for high performance, high safety and diversified development, and is the cornerstone driving the progress of modern flexible packaging technology.
