Polyurethanes are extensively and successfully used as adhesives and sealants, and they have an excellent record of durability. Polyurethane-based adhesives form tough bonds with high peel strength. They have better low temperature strength than other adhesives. They have exceptionally high strength at cryogenic temperatures. They have good chemical resistance, although not generally as good as epoxies or acrylics. Urethanes do not have high temperature resistance. Maximum upper use limits are about 150°C, and most formulations are used below 100°C.
RESULTING PROPERTIES
The formulation above is for a two component polyurethane adhesive with a long pot life. This type of adhesive is often used for laminating flexible substrates. Often additives are not required to provide flexibility or toughness. Polyurethanes have the capability of providing these properties through manipulation of the resulting molecule by proper choice of isocyanate and polyol. However, additives are used mainly to stabilize the adhesive relative to moisture, oxidation, UV, etc.
