| 摘要 |
Bis(cyclic ureas) are disclosed which have the formula <IMAGE> wherein R is <IMAGE> and CnH2n is ethylene or 1,3-propylene each of which can be substituted by one or more inert substituents. These compounds are useful as masked diisocyanates which, on heating in the presence of a polyol and, optionally, a polyurethane catalyst, give rise to polyurethane resins. Accordingly, they are useful as a component of storage stable compositions which are convertible to polyurethanes upon heating. Such compositions are particularly useful as solvent-less coating compositions. The properties of the above compounds are distinguished in a number of respects from the known bis(cyclic ureas) in which CnH2n has 4 or more carbon atoms in the chain between the valencies. Illustratively, the above compounds are more stable on exposure to heat in the absence of catalysts but, in the presence of polyurethane catalysts, react with polyols at a significantly faster rate than the prior art compounds. |
