Desmocap® prepolymers for flexible sealants
Epoxy resins have excellent protective properties but can be brittle, unless they are modified using flexible urethane prepolymers.
Desmocap® branched aromatic ether/urethane resins from Covestro are effective flexibilizers for 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 sealant and acts as a plasticizer.
The long, flexible polyoxypropylene units in Desmocap® prepolymers decrease the crosslink density in the sealant, which results in increased elasticity – 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 adhesives and sealants.