Key points for food safety compliance of flexible packaging polyurethane adhesives

Flexible packaging polyurethane adhesives are widely used in food packaging composite films. Food safety compliance is the bottom line for the product's successful launch, and the core lies in three dimensions: raw material selection, migration control, and detection management.

 

The main raw materials of polyurethane adhesives, such as polyols, isocyanate monomers, and various additives, all need to comply with the relevant regulations for food contact materials. Free isocyanate monomers have high reactivity. If the residual content is high, they are more likely to migrate when in contact with oily, water-containing foods, and under high-temperature steaming conditions. Therefore, in the formulation design, the residual monomer content should be controlled, and a raw material system with low free monomers should be selected.

The impact of different contents on migration risks is significantly different. Oily, acidic, and alcoholic foods will accelerate the outward migration of the adhesive layer components. In the selection of packaging types, polyurethane adhesives with extraction resistance should be preferred. The curing process is also a key point for compliance control. Adequate curing can allow unreacted groups to complete cross-linking, reducing the amount of migratable small molecules. Insufficient curing temperature and time will directly increase the risk of non-compliance.

 

In addition to formulation and process control, corresponding migration simulation tests need to be carried out to evaluate in the actual food packaging scenarios. With the continuous tightening of industry regulation, low migration and low residual polyurethane adhesives have become the mainstream development direction. Considering both bonding performance and safety attributes, they can be adapted to various food soft packaging scenarios such as snack foods, cooked food, and steamed food packaging.