Polyurethane Prepolymers

Blocked Prepolymer


Isobloc blocked TDI prepolymer for flexible epoxy-urethane coatings.

Epoxy coatings can be brittle, but they can be made more flexible with the addition of blocked polyurethane prepolymers.

Isoloc C11 is a branched TDI prepolymer based on polyether polyols. The prepolymer is blocked with a bio based blocking agent, unlike traditional blocked prepolymers which are blocked with hazardous nonyl phenol. Isobloc C11 reacts with amine crosslinkers and epoxy resins to form a urethane – epoxy hybrid polymer. The blocking agent remains in the cured coating and acts as a plasticiser.

Isobloc C11 is lower viscosity than nonyl phenol blocked prepolymers, making handling easier.

Incorporating Isobloc C11 into an epoxy coating results in increased impact resistance and higher flexibility.

Technical Data

Product Isocyanate Type NCO Content (%) Viscosity 25ºC (cPs) Calculated NCO Equivalent Weight Calculated Epoxy Equivalent Weight
Isobloc C11 Blocked TDI 2.1 – 2.4 (Blocked) 15,000 – 55,000 1750 – 2000 (Blocked) 875 – 1000


Related Articles

Evaluation of the Physical Properties of Epoxy Resins modified with blocked TDI prepolymer

Karl Prescott Isothane Ltd, Newhouse Road, Huncoat Business Park, Accrington, Lancashire. BB5 6NT. United Kingdom. ABSTRACT Coatings based on epoxy resins have a number of good characteristics but are prone to brittleness, which limits their use in areas where good impact resistance and flexibility are required. Incorporating a blocked prepolymer into the epoxy increases the…

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