Dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI)
Hydrogenated MDI keeps MDI’s strength-building shape but swaps aromatic rings for saturated ones, giving tough, non-yellowing elastomers and coatings.
Dicyclohexylmethane-4,4′-diisocyanate (H₁₂MDI, also called HMDI) is MDI with both benzene rings fully hydrogenated to cyclohexane rings. It has a molecular weight of about 262.4 g/mol and 32.0% NCO, and is supplied as a liquid mixture of stereoisomers.
H₁₂MDI is used for high-performance, light-stable polyurethanes:
The saturated rings remove the UV-absorbing aromatic structure while retaining a rigid, symmetric shape that builds strong hard segments. Its NCO groups are less reactive than MDI’s, so formulations often use catalysts or more reactive amine partners.
H₁₂MDI is a diisocyanate sensitizer. Handle with respiratory and skin protection appropriate to the task, and keep containers sealed and dry.
No. HDI is a linear six-carbon diisocyanate; H₁₂MDI has two saturated rings joined by a methylene bridge, giving stiffer hard segments.
For applications needing UV stability and clarity with high mechanical performance, at a higher cost than MDI.
