| 摘要 |
Cellular polyurethanes are obtained by reacting a mixture comprising a major proportion of a diaryl methane diisocyanate and 5%-50% of a polyisocyanate of a functionality greater than 2, with a polyether containing at least two hydroxyl groups, and water. Diphenyl methane and phenyltolyl methane diisocyanates are specified, together with lists of suitable reactants. The polyisocyanate of functionality greater than 2 may be obtained by interacting some of the diisocyanate with a polyhydric alcohol, or it may be partially polymerized e.g. by catalysts, or when the diisocyanate is being prepared by phosgenating crude diaminodiarylmethane, the polyamines present are also phosgenated. The ionizable chlorine content of the polyisocyanate composition is preferably from 0,01%-3% by weight. The one stage or two stage process may be used, and the product may contain known additions, e.g. fire proofers, surface active agents, fillers and colours. The reaction is carried out in the presence of a catalyst, e.g. a tertiary amine.ALSO:Cellular polyurethanes are obtained by reacting a mixture comprising a major proportion of a diarylmethane diisocyanate and 5-50% of a polyisocyanate of a functionality greater than 2, with a polyether containing at least two hydroxyl groups, and water. Diphenyl methane and phenyl tolyl methane diisocyanates are specified together with lists of suitable reactants. The product may have the known additions e.g. fire proofers, surface active agents as pore modifiers, fillers and colours, and it may be prepared by the one stage or two stage technique. |
