Flexible adhesive applications
Polyurethane: A tailor-made solution for flexible packaging
For general-purpose, medium-performance or high-performance flexible packaging lamination applications polyurethane (PU) adhesives offer a tailor-made solution. Covestro PU raw materials are a proven technology.
Our raw materials are used to produce one- (1K) and two- (2K) component solventborne, solventfree and waterborne adhesives that fulfill requirements for many flexible packaging applications.
The type of PU building block is determined by the product to be filled, filling process and end use.
Requirements for adhesives differ from market segment to market segment. Laminated film-to-film or film-to-foil composites are divided into three areas:
- General-purpose laminates comprise film-to-film or film-to-paper composites. They are typically used to pack dry food in room temperature storage conditions.
- Medium-performance laminates are used in fatty or acid food packaging and foil laminates.
- High-performance laminates are used for boil-in bag applications, hot fillings, sterilization processes up to 134°C, and pharmaceuticals.
As a flexible packaging application becomes more demanding, the adhesive and its PU building blocks must demonstrate greater chemical and heat resistance as well as excellent food safety properties.
The resistance of a PU adhesive polymer is significantly influenced by the chosen polyurethane polymer building blocks, i.e. polyether or polyester polyol, the crosslinking density and the molecular weight of the adhesive polymer.