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
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.