The Sole Bonding System of Polyurethane
Adhesives based on polyurethane dispersions have become increasingly important in the footwear industry due to their high level of adhesive performance and rising concerns for protecting the environment and providing a safer workplace for employees.
Polyurethane dispersions are the raw material of choice for formulating water-based adhesives for footwear sole bonding as they provide the following properties:
- They provide excellent initial bond strength for high production efficiency
- They provide high adhesion performance and produce a bond line that does not discolor over time
- They are environmentally friendly because of their low VOC content
- They contribute to a safe working environment in shoe production
The performances of PUD based adhesives is at the same level as solvent-based adhesives. Certain properties can be superior with water-based Polyurethane systems. An additional advantage of these systems is their ability to bond to substrates containing plasticizers, which are commonly used to manufacture shoe soles.
There are many products which are good choice for footwear applications. The final properties, like heat resistance and long-term durability, can even be improved by the addition of 3-5% of an emulsifiable polyisocyanate.