Overview of PU Adhesive for Flexible Packaging

Flexible packaging Polyurethane Adhesive is a key material used in the production of flexible packaging composite materials for food, daily chemicals, pharmaceuticals and other products. Its main function is to firmly bond films of different properties (such as BOPP, PET, PA, AL, CPP, PE, etc.) together through dry lamination process.

 

The core component of this type of adhesive is polyurethane, which contains a large number of carbamate bonds in its molecular chain. By designing and adjusting the ratio of polyester or polyether polyols to diisocyanates, adhesives with excellent performance can be synthesized. Its greatest advantage lies in its excellent bonding performance, which can overcome the differences in surface polarity and chemical structure among various film materials, forming a high-strength and durable composite layer to ensure the integrity of the packaging bag. Meanwhile, the cured adhesive layer is flexible and resistant to bending, capable of adapting to the deformation of the packaged contents and mechanical stress during processing, thus preventing delamination and cracking.

 

With the enhancement of environmental protection and safety awareness, the development of polyurethane adhesives for flexible packaging has undergone a major transformation from solvent-based to solvent-free. Solvent-free polyurethane adhesives have become the mainstream trend due to their characteristics such as no volatile organic compounds, safe production, energy conservation and high efficiency, and excellent hygiene performance. They are usually two-component reactive systems, with low viscosity at room temperature, which is convenient for coating, and they undergo rapid chemical reactions to complete curing after heating.

 

In addition, functional products for special requirements, such as retaming packaging (high-temperature retaming above 121℃) and resistance to media (acid, oil, and spicy contents), are also constantly evolving to meet increasingly demanding packaging application scenarios. In conclusion, polyurethane adhesives for flexible packaging are high-performance, safe, environmentally friendly and continuously innovative materials, and are an indispensable part of the modern flexible packaging industry.