Pre-polymers for flexible epoxy and urethane coatings : Desmocap®

Epoxy resins have excellent protective properties and are widely used as primer layers in corrosion protection coating systems. They can be brittle, though, unless they are modified using flexible urethane prepolymers.

Desmocap® branched aromatic ether/urethane resins from Covestro are effective flexibilizers for epoxy coatings and sealants.

These nonsolvent prepolymers are based on polyoxypropylene glycol (POPG) and toluene diisocyanate (TDI) and are blocked with alkylphenols. They react with amine crosslinkers and epoxy resins to form hybrid epoxy-urethane (polyurea-urethane-epoxy) polymers. The released alkylphenol remains in the coating and acts as a plasticizer.

The long, flexible polyoxypropylene units in Desmocap® prepolymers decrease the crosslink density in the coating, which results in increased elasticity and improved impact resistance – even at lower temperatures.

Epoxies modified with our Desmocap® resins also have:

•     Lower glass transition temperatures
•     Improved adhesion and intercoat adhesion

Desmocap® prepolymers are also used by themselves – individually or in combination – to prepare flexible coatings and sealants