Replacing Volatile Organic Solvents in Shoemaking Adhesives -
Oct 19, 2011 While water-based adhesives permeated through
footwear manufacturing during the 1990s,1 fear of tearing the
sole and upper apart long kept solvent-borne products
exclusively dominant in that area. But in recent years, water-
based formulations suitable even for this demanding application
have emerged. With the help of this kind of adhesive, a
multinational material producer this year unveiled an entirely
solvent-free "green shoe concept".2 Figure 1: Waterborne
polyurethane adhesives help deliver the "Green Shoe" concept.
Credit: Bayer MaterialScience To do this, water-based adhesive
development has had to overcome the last exclusive bastion of
solvent-borne products - heat-activated attachment of soles and
uppers. That process traditionally applies one pre-coat solvent-
borne polyurethane (PU) adhesive to the shoe upper, then lets
the solvent evaporate, before the process is repeated with a
second solvent-borne PU layer. Heating the uppe