4.4- Dicyclohexyl diisocyanate HMDI

A study in mice examined immune responses following topical exposure to three allergenic diisocyanates diphenylmethane-4,4 -diisocyanate (MDI), dicyclohexyl-methane-4,4 -diisocyanate (HMDI), and isophorone diisocyanate (IPDI). Contact and respiratory sensitizers induce differential immune responses in mice characteristic of Thl and Th2 T helper cell activation, respectively. All three chemicals are contact allergens. MDI is, in addition, a known human respiratory allergen. HMDI and IPDI did not produce an immunologic response in the mouse similar to MDI. These findings suggest that HMDI has much less potential to cause respiratory sensitization in humans than does MDI ... 

The saturated analog of MDI, 4,4 dicyclohexyl methane diisocyanate, has found limited used as an aiphatic isocyanate in adhesives. This material is known by a variety of names including Desmodur W (Mobay), hydrogenated MDI (or HMDI or H12 MDI), reduced MDI (RMDI), and saturated MDI (SMDI). It is a low viscosity liquid with a fairly high vapor pressure so it too must be handled with care. In adhesive compositions, the diisocyanate usually is used to make an isocyanate functional prepolymer by reacting excess diisocyanate with a hydroxyl or amine functional polymer such as a polyester diol. 

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